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Helichrysum petiolare and Helichrysum odoratissimum, collectively known as ‘Imphepho’, are popular medicinal herbs that are indigenous to South Africa. The species are used interchangeably to relieve gastrointestinal and respiratory conditions, fever and urinary tract infections, implying that they produce antibacterial compounds. Although these herbs are sold in informal markets, they have not been commercialized. The aim of this study was to compare the chemical profiles and the antimicrobial activities of solvent extracts of the two species. The profiles of the smoke condensates were also compared, since the smoke from both species is inhaled during cultural rituals to induce central nervous system effects. After optimizing the extractant, the chemical profiles of aqueous methanol extracts of the aerial parts of twelve H. odoratissimum and fifteen H. petiolare samples, collected from several different localities, were obtained using ultra performance liquid chromatography-mass spectrometry (UPLC-MS). Three isomeric compounds were found to be present in both species. The construction of chemometric models from the data indicated a large degree of inter-population variation within H. odoratissimum, with the samples loosely clustering into two main groups. In contrast, the chemistry of H. petiolare was highly conserved. Discriminant analysis identified four distinguishing marker compounds for each species. One of the isomers common to both species, was isolated from H. odoratissimum and identified as 4,5-dicaffeoylquinic acid using nuclear magnetic resonance (NMR) spectroscopy, and is herein reported for the first time from the two species. Following validation of a developed UPLC-photodiode array (PDA) detection method, it was determined that the concentrations of the compound ranged from 3.89 - 31.1 µg/g in H. odoratissimum and from 2.3 to 13.4 µg/g in H. petiolare. High performance thin layer chromatography (HPTLC) fingerprints also indicated a greater degree of chemical variation within H. odoratissimum than in H. petiolare. This was confirmed through multivariate analysis of densitograms obtained from images of the fingerprints through the application of rTLC software, effectively mirroring the UPLC-MS results. The antibacterial activity of extracts of all the samples was determined using the minimum inhibitory concentration (MIC) serial dilution assay against selected Gram-positive (Staphylococcus saprophyticus, Enterococcus faecalis, Streptococcus agalactiae) and Gram-negative (Proteus mirabilis, Escherichia coli, Moraxella catarrhalis) pathogens that affect the urinary, respiratory and gastro-intestinal tracts. The MICs obtained for H. odoratissimum extracts indicated that these were more effective towards a larger range of bacteria than extracts of H. petiolare. The methanol extracts yielded average MICs denoting noteworthy or moderate activity towards three pathogens (E. coli, M. catarrhalis and S. agalactiae), while the chloroform:methanol extracts displayed noteworthy or moderate activity towards the same three pathogens, but also towards E. faecalis. These results justify to some degree the traditional use of H. odoratissimum to treat conditions of the gastro-intestinal, respiratory and urinary tracts. The UPLC-PDA profiles of smoke condensates of the two species, obtained under controlled conditions, revealed five major compounds that were common to both species. Although the similarity of the smoke profiles rationalises their interchangeable use for inhalation, the solvent extracts displayed little congruence regarding their chemical profiles or antibacterial activities.

The knowledge of the levels of polyphenols present in green coffee beans from different geographical origins is important to identify beans that can provide better coffee quality. The aim of this study was to determine the concentrations of both soluble and cell wall-bound polyphenols in green coffee beans (Coffea arbica L.) from different cultivation regions of Ethiopia. A total of 100 samples were collected from four geographical regions (East, West, South, Northwest) and comprised eight commercial types of coffee (Harar, Jimma, Kaffa, Wollega, Sidama, Yirgacheffe, Finoteselam and Benishangul). The total concentrations of soluble and cell wall-bound polyphenols and flavonoids in the sample extracts were determined using the Folin-Ciocalteu and aluminum chloride reagent methods, respectively. Qualitative analysis was also performed by using high performance thin layer chromatography (HPTLC). Results revealed that chlorogenic acids as the predominant constituents of the phenolic fraction of the green coffee beans. The total soluble polyphenol, cell wall-bound polyphenol and flavonoid contents of the green coffee beans were in the range of 21.8–43.6 milligrams of gallic acid equivalents per gram (mg GAE g−1), 8.6–15.3 mg GAE g−1 and 3.3–6.2 milligrams of (+)-catechin equivalents per gram (mg CE g−1) of dry mass, respectively. Cell wall-bound polyphenols were found to contribute significantly (21.0–32.5%) to the total polyphenol contents (TPC) of the green coffee beans. The polyphenol contents of green coffee beans have been found to vary with geographical origins. Harar coffee contained significantly (p

Chromones are naturally occurring phenolic compounds that are universally present in a healthy human diet. To date, thousands of chromone derivatives, including chromone glycosides have been discovered, both from natural and synthetic origin. Many plant genera, including Aloe, Aquilaria, Cassia, Hypericum and Polygonum, are rich sources of chromones. Several genera of fungi, such as Aspergillus, Mycoleptodiscus, Orbiocrella, and Penicillium produce bioactive chromones. This class of compounds is mainly associated with anti-oxidant, antimicrobial, anticancer and anti-inflammatory activities. Various in vitro, in vivo and clinical studies have established the role of chromones in alleviating allergies, reducing oxidative damage, inhibiting cancer, infections and inflammation, and for treating neurological and psychiatric disorders. This review focuses mainly on natural chromones, and elaborates on their nutritional benefits, pharmacological activities, and mechanisms of action. Various scientific databases, including PubMed, Scopus and Google Scholar, were used to find relevant literature on chromones covering all available literature up to, and including the year 2019. This critical analysis of completed research regarding the nutraceutical properties of various chromone derivatives may provide new insight to scientists working in related fields.

Fumonisins are common contaminants of maize. The neutral red assay, using the RTL-W1 trout liver cell line, and the fish embryo test (FET), using zebrafish, were selected to assess the effect of pH on the cytotoxicity, acute toxicity and teratogenicity of fumonisin B1 (FB1). The results demonstrated that FB1 exerts low cytotoxicity towards RTL-W1 cells without pH adjustment (IC50 1 746 μM), and no cytotoxicity after pH-adjustment to physiological conditions. The LC50 value for FB1 in the FET (1 058 μM at 48 h) confirmed low acute toxicity. Adjusting the pH to physiological conditions reduced the acute toxicity of FB1 towards zebrafish embryos, emphasising the importance of acidity/basicity of the medium in toxicity testing. Hydrolysed FB1 was less toxic than FB1 (LC50 2 690 μM at 48 h), and neither were teratogenic towards zebrafish embryos. Results confirm that the FET may account for effects not observable in cell cultures.

Acacetin (5,7-dihydroxy-4-methoxyflavone) is a naturally occurring flavonoid, known to possess numerous pharmacological properties, including neuroprotective, cardioprotective, anticancer, anti-inflammatory, antidiabetic, and antimicrobial activities. The molecule is widespread throughout the Plant Kingdom, but is particularly abundant in the Asteraceae, Euphorbiaceae, Passifloraceae, Lamiaceae and Malvaceae families. It has been shown to exhibit strong inhibitory effects against glutathione reductase, cyclo-oxygenase, acetylcholinesterase, aldose reductase and xanthine oxidase enzymes. A comprehensive overview of the potential therapeutic applications of acacetin was prepared after collating selected peer-reviewed papers, accessed from online scientific databases, specifically PubMed, Web of Science and Scopus. The mechanism of action, dose forms and structure-activity relationships of the molecule are some of the aspects discussed in the review, to facilitate further research and use of this molecule.

The South African Salvia species, Salvia africana-lutea, S. lanceolata and S. chamelaeagnea, are widely used to treat fever and inflammation associated with skin and lung infections. The aim of this study was to explore the non-volatile secondary metabolites and the phytochemical variation within these lesser known species, to support product development and commercialisation. Chemical profiles of the methanol extracts of 81 wild-harvested samples were obtained using ultra performance-quadrupole-Time-of-Flight-mass spectrometry (UPLC-qToF-MS). Forty-one compounds, including caffeic acid, rosmarinic acid, carnosol, carnosic acid and ursolic acid, were detected and confirmed across the three species. Nineteen compounds were tentatively identified of which 14 have not been reported in these species. Principal component analysis revealed distinct clusters corresponding to the three species, confirming chemical differences. Marker compounds for each species were revealed using orthogonal projection to latent structures-discriminant analysis. Further chemometric analysis reflected a degree of intraspecies variation, although the chemistry within populations was mostly conserved. Potential chemotypes for each species were identified through unique compounds associated with each group. The concentrations of medicinally important metabolites, namely, rosmarinic acid, carnosol, carnosic acid and ursolic acid, were determined, using validated UPLC-PDA methods. Ursolic acid was present at levels up to 38.2 mg/g, confirming that these species are a rich source of this compound. No similar studies combining liquid chromatography with chemometric analysis, and utilising a large sample size from various habitats, have been reported for these three Salvia species. The results will guide selection of cultivars with the best attributes for the intended therapeutic application, thereby protecting wild populations from over-exploitation.

Terminalia sericea is used throughout Africa for the treatment of a variety of conditions and has been identified as a potential commercial plant. The study was aimed at establishing a high-performance thin layer chromatography (HPTLC) chemical fingerprint for T. sericea root bark as a reference for quality control and exploring chemical variation within the species using HPTLC metabo3lomics. Forty-two root bark samples were collected from ten populations in South Africa and extracted with dichloromethane: methanol (1:1). An HPTLC method was optimized to resolve the major compounds from other sample components. Dichloromethane: ethyl acetate: methanol: formic acid (90:10:30:1) was used as the developing solvent and the plates were visualized using 10% sulfuric acid in methanol as derivatizing agent. The concentrations of three major bioactive compounds, sericic acid, sericoside and resveratrol-3-O-&beta, rutinoside, in the extracts were determined using a validated ultra-performance liquid chromatography-photodiode array (UPLC-PDA) detection method. The rTLC software (written in the R-programming language) was used to select the most informative retardation factor (Rf) ranges from the images of the analysed sample extracts. Further chemometric models, including principal component analysis (PCA) and hierarchical cluster analysis (HCA), were constructed using the web-based high throughput metabolomic software. The rTLC chemometric models were compared with the models previously obtained from ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS). A characteristic fingerprint containing clear bands for the three bioactive compounds was established. All three bioactive compounds were present in all the samples, although their corresponding band intensities varied. The intensities correlated with the UPLC-PDA results, in that samples containing a high concentration of a particular compound, displayed a more intense band. Chemometric analysis using HCA revealed two chemotypes, and the subsequent construction of a loadings plot indicated that sericic acid and sericoside were responsible for the chemotypic variation, with sericoside concentrated in Chemotype 1, while sericic acid was more abundant in Chemotype 2. A characteristic chemical fingerprint with clearly distinguishable features was established for T. sericea root bark that can be used for species authentication, and to select samples with high concentrations of a particular marker compound(s). Different chemotypes, potentially differing in their therapeutic potency towards a particular target, could be distinguished. The models revealed the three analytes as biomarkers, corresponding to results reported for UPLC-MS profiling and thereby indicating that HPTLC is a suitable technique for the quality control of T. sericea root bark.

Artemisia afra (African wormwood) is a popular medicinal plant of southern Africa and is an excellent candidate for commercialisation. This current study was aimed at exploring the phytochemistry and chemical variation of non-volatile compounds within wild populations of A. afra, and developing chromatographic quality control protocols for raw materials based on the identification of marker compounds. Chromatographic data, from samples representing 12 distinct populations, were obtained using liquid chromatography-mass spectrometry. An untargeted chemometric approach revealed three clusters. Marker compounds for each cluster, revealed through discriminant analysis, were isolated and identified using NMR spectroscopy, as acacetin (1) (Group 1), chrysoeriol (2) (Group 2), and 3,5-di-O-caffeoylquinic acid (3) and scopoletin (4) (Group 3). In addition, (3) and rutin (5), (both reported for the first time from A. afra), and (1), (2), (4) and 4-caffeoylquinic acid (6) were established as reliable markers for species identification, since they were abundant in most samples. Quantitative analysis using a validated method established (4) as the dominant compound in the samples (1080–19,600 μg/g dry weight (d.w.)), followed by (5) (49.5–2490 μg/g d.w.). A high performance thin layer chromatography (HPTLC) method was developed. The Rf values and colours of the bands corresponding to the marker compounds were recorded so that these compounds could be easily identified for quality control purposes. Multivariate analysis of the data using the rTLC online application confirmed the presence of different chemical groupings within the samples. It was deduced that quantitative, rather than qualitative differences, characterised the samples. Future research should focus on comparing the efficacy of the various chemical clusters in multi-target biological assays aligned to the traditional use of the plant.

Terminalia sericea Burch. ex. DC. (Combretaceae) is a popular remedy for the treatment of infectious diseases. It is widely prescribed by traditional healers and sold at informal markets and may be a good candidate for commercialisation. For this to be realised, a thorough phytochemical and bioactivity profile is required to identify constituents that may be associated with the antibacterial activity and hence the quality of raw materials and consumer products. The aim of this study was to explore the phytochemistry and identify the antibacterial constituents of T. sericea root bark, using a metabolomic approach. The chemical profiles and antibacterial activities of 42 root bark samples collected from three districts in the Limpopo Province, South Africa, were evaluated. Dichloromethane:methanol (1:1) extracts were analysed using ultraperformance liquid chromatography (UPLC)-mass spectrometry (MS), and chemometric models were constructed from the aligned data. The extracts were tested against Bacillus cereus (ATCC 11778), Staphylococcus epidermidis (ATCC 12223), Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 8739), Klebsiella pneumoniae (ATCC 13883), Pseudomonas aeruginosa (ATCC 27853), Shigella sonnei (ATCC 9292) and Salmonella typhimurium (ATCC 14028), using the minimum inhibition microdilution assay. Nine compounds, sericic acid, sericoside, resveratrol-3-O-&beta, rutinoside, ellagic acid, flavogallonic acid dilactone, methyl-flavogallonate, quercetin-3-(2&prime, &prime, galloylrhamnoside), resveratrol-3-(6&prime, galloyl)-O-&beta, d-glucopyranoside and arjunetin, were isolated from the root bark. All the compounds, with the exception of sericic acid, sericoside and resveratrol-3-O-&beta, rutinoside, were isolated for the first time from the root bark of T. sericea. Chemometric analysis revealed clustering that was not population specific, and the presence of three groupings within the samples, characterised by sericic acid, sericoside and an unidentified compound (m/z 682/4.66 min), respectively. The crude extracts from different populations displayed varied antibacterial activities against S. typhimurium (minimum inhibitory concentrations (MICs) 0.25&ndash, 1.0 mg/mL), but similar activity towards Bacillus cereus (1.0 mg/mL). Several compounds present in the root bark were highly active towards all or most of the pathogens tested, but this activity was not reflected by the chemical profiles of extracts prepared from the individual samples. Among the pure compounds tested, only flavogallonic acid dilactone and methyl-flavogallonate exhibited broad-spectrum activity. A biochemometric analysis indicated that there was no consistent association between the levels of phytochemicals and the activity of the active or non-active extracts. Although it was deduced that the major constituents of T. sericea root bark contributed to the chemotypic variation, further investigation of the interactions of compounds present in the root bark may provide antibacterial efficacies not evident when examining compounds singularly. The data reported herein will provide information that is fundamentally important for the development of quality control protocols.

Sceletium tortuosum (Aizoaceae) is widely recognised for the treatment of stress, anxiety and depression, as well as for obsessive compulsive disorders. A comprehensive intraspecies chemotypic variation study, using samples harvested from two distinct regions of South Africa, was done using both proton nuclear magnetic resonance (1H-NMR) spectroscopy of methanol extracts (N = 145) and ultra performance liquid chromatography-mass spectrometry (UPLC-MS) of acid/base extracts (N = 289). Chemometric analysis of the 1H-NMR data indicated two main clusters that were region-specific (Northern Cape and Western Cape provinces). Two dimensional (2D) NMR was used to identify analytes that contributed to the clustering as revealed by the S-plot. The sceletium alkaloids, pinitol and two alkylamines, herein reported for the first time from S. tortuosum, were identified as markers that distinguished the two groups. Relative quantification of the marker analytes conducted by qNMR indicated that samples from the Northern Cape generally contained higher concentrations of all the markers than samples from the Western Cape. Quantitative analysis of the four mesembrine alkaloids using a validated UPLC-photo diode array (PDA) detection method confirmed the results of qNMR with regard to the total alkaloid concentrations. Samples from the Northern Cape Province were found to contain, on average, very high total alkaloids, ranging from 4938.0 to 9376.8 mg/kg dry w. Regarding the Western Cape samples, the total yields of the four mesembrine alkaloids were substantially lower (averages 16.4–4143.2 mg/kg). Hierarchical cluster analysis of the UPLC-MS data, based on the alkaloid chemistry, revealed three branches, with one branch comprising samples primarily from the Northern Cape that seemed somewhat chemically conserved, while the other two branches represented mainly samples from the Western Cape. The construction of an orthogonal projections to latent structures-discriminant analysis model and subsequent loadings plot, allowed alkaloid markers to be identified for each cluster. The diverse sceletium alkaloid chemistry of samples from the three clusters may facilitate the recognition of alkaloid profiles, rather than individual compounds, that exert targeted effects on various brain receptors involved in stress, anxiety or depression.

Athrixia phylicoides, known as “bush tea”, grows abundantly in South Africa. An infusion of the leaves is used as a beverage and to treat a multitude of health conditions. The aim of this study was to investigate the chemical variation within A. phylicoides and to identify characteristic compounds for quality control. Samples from 12 locations in South Africa were analysed using ultra-performance liquid chromatography. Hierarchical cluster analysis of the aligned ultra-performance liquid chromatography-time-of-flight mass spectrometry data indicated two groups on the resulting dendrogram, representing 48 samples. Five marker compounds, identified through visual inspection and the construction of a discriminant analysis model, were evident on the ultra-performance liquid chromatography-MS profiles. Four of these compounds were isolated and identified, three as hydroxy methoxyflavones and the fourth as a coumarate, using nuclear magnetic resonance spectroscopy. An ultra-performance liquid chromatography-photodiode array method was developed and validated for the determination of the marker compounds using the isolates as standards. The limits of detection for the four compounds ranged from 0.92 – 2.50 µg/mL. Their recoveries at three concentration levels (1.00, 10.0, and 100 µg/mL) were between 97.0 and 101%, while acceptable intra- and inter-day precision was obtained as reflected by percentage relative standard deviation values below 2.24%. The concentrations of all the marker compounds were found to be higher in samples corresponding to Group 1 of the dendrogram than in those from Group 2. This may be attributable to differences in altitude, climate, and some edaphic factors. Identification of these marker compounds will make a valuable contribution towards the quality control and sustainable commercialisation of bush tea.

Chemical interrogation of the Sceletium genus and Amaryllidaceae family of plants has yielded a diverse array of aryl-hydroindole containing alkaloids. Included in this class is channaine, which was tentatively identified, without comprehensive structural elucidation from Sceletium tortuosum in 1957. Following its isolation from S. strictum, the structure of channaine was eventually resolved by X-ray crystallographic analysis, which revealed an unusual cage-like ring structure at the interface of two aryl-hydroindole subunits. However, since this report in 1978, channaine has not re-appeared in the literature. In this letter, the full NMR characterisation of channaine, isolated from S. tortuosum collected from St Helena in the Western Cape Province of South Africa, is reported for the first time.

Ethnopharmacological relevance Many species within the family Combretaceae are popular medicinal plants that are used traditionally to treat various conditions, of which many are related to bacterial infections. Global concerns regarding the increasing resistance of pathogens towards currently available antibiotics have encouraged researchers to find new drugs with antibacterial activity, particularly from plant sources. Aim of the study This study was aimed at exploring the broad-spectrum antibacterial potential of methanol extracts of species representing four genera of Combretaceae (Combretum, Pteleopsis, Quisqualis, Terminalia), indigenous to South Africa, using a biochemometric approach. Materials and methods The microdilution assay was used to determine the antibacterial activities, measured as minimum inhibitory concentrations (MICs), of the 51 methanol extracts representing 35 Combretaceae species, against nine species of pathogenic bacteria. Integrative biochemometric analysis was performed, thereby correlating the MIC values with the metabolomic data obtained from ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) analysis. Orthogonal projections to latent structures-discriminant analysis (OPLS-DA) models were constructed for six pathogens displaying variation in their susceptibility towards the extracts. Results Evaluation of the overall MIC values obtained indicated that extracts of species from the four genera displayed the highest activity towards Bacillus cereus ATCC 11778 (average MIC 0.52 mg/mL) and Salmonella typhimurium ATCC 14028 (average MIC 0.63 mg/mL). These bacteria were the most sensitive Gram-positive and Gram-negative bacteria, respectively. Extracts from Combretum acutifolium, Combretum imberbe and Combretum elaeagnoides were the most active, with average MIC values of 0.70 mg/mL, 0.52 mg/mL and 0.45 mg/mL, respectively. Five triterpenoid compounds were tentatively identified as biomarkers from the biochemometric analysis. Conclusion Correlation of the phytochemistry of species from four genera in the Combretaceae family with antibacterial activity revealed that triterpenoids are responsible for the broad-spectrum antibacterial activity observed.

Ethnopharmacological relevance Khat, the leaves of Catha edulis, is used as a “natural amphetamine-like” stimulant in eastern and southern Africa, as well as in the Arabian Peninsula. Leaves are masticated to elicit a state of euphoria. Although the psychostimulatory effects of the leaves are attributed to the presence of phenylpropylamino alkaloids ( i.e. cathinone, cathine and norephedrine), the extent of permeation of these alkaloids across the oral and intestinal mucosa has not been established. Materials and methods Cathinone was isolated in the form of the oxalate salt from young buds, following acid-base extraction. High performance countercurrent chromatography (HPCCC) was used to isolate cathine and norephedrine, following borohydride reduction of a mixture of the three alkaloids. The in vitro permeability of these three alkaloids in their pure form, as well as in a crude extract, was evaluated across Caco-2 cell monolayers and across excised porcine intestinal, sublingual and buccal tissues. Results The purities of the isolated cathine and norephedrine were in excess of 90%, thereby proving that HPCCC can be applied for efficient separation of these alkaloids from extracts of Khat. The apparent permeability (P app ) coefficients for the Khat alkaloids in their pure form were all above 1.0×10 −6 cm/s, indicating that the transport of the three alkaloids across the selected biological membranes is comparable to that of the highly permeable reference compound, caffeine. Although readily transported across the various membranes, the alkaloids were transported to a lesser extent when present in a leaf extract, suggesting that other phytochemicals present in the extract influence their permeation. Conclusions These results provide evidence that chewing of Khat contributes to the buccal and sublingual absorption of the psychoactive alkaloids in the bloodstream directly across the oral mucosal membranes. In addition, it confirms that these metabolites will be readily absorbed from the gastrointestinal tract when swallowed.

The volatile constituents of nine liverworts species ( Asterella marginata , Dumortiera hirsuta , Fossombronia swaziensis , Marchantia pappeana , Marchantia polymorpha subsp. ruderalis , Pallavicinia lyellii , Plagiochasma rupestre , Riccia albolimbata and Symphyogyna podophylla ) from South Africa were determined by gas chromatography. Where possible the volatile constituents identified were compared to those reported for the same species from other countries. Among the analysed liverworts, the chemical compositions of A. marginata , F. swaziensis , M. pappeana , and R. albolimbata are reported for the first time. Each of the analysed liverwort species produced its own characteristic components. Thujopsanes, chamigranes and cuparanes were found to be the most characteristic components of M. polymorpha subsp. ruderalis . The presence of dumortane-type sesquiterpenoids in D. hirsuta indicated that this species is similar in chemistry to an Argentinean sample. This is one of only a handful of reports on the presence of this sesquiterpene-type in liverworts. Simple thallose liverworts, S. podophylla and P. lyellii , were characterized by the presence of labdane-type diterpenoids. In addition, the antimicrobial activities of chloroform:methanol (1:1) extracts of the liverworts were evaluated against several important human pathogens using the serial dilution assay. Four of the liverwort species were active against Pseudomonas aeruginosa with MIC values ranging from 0.50 to 1.0 mg/mL. Some activity (MIC value of 1.0 mg/mL) was also recorded for the crude extracts of P. lyellii and M. pappeana against Escherichia coli. The extract of S. podophylla displayed the best activity towards the yeast Cryptococcus neoformans (MIC = 1.0 mg/mL). Although approximately 300 liverwort species occur in southern Africa, a Scopus search confirmed that this is the first report of the volatile profiles and biological properties of species from the region.

Mango blossom malformation, caused by infection of mango panicles and young shoots by Fusarium species, leads to significant reductions in fruit yield. Previously, chemometric models were established that allowed biomarkers associated with resistance in tolerant cultivars to be identified. High concentrations of these biomarkers, mangiferin, maclurin and maclurin O-galloyl-glucoside, are inherent genetic traits of some cultivars and have been linked to their ability to confine Fusarium infection. In this study, phenolic profiles of mature leaf extracts from cultivars exhibiting different levels of resistance to Fusarium infection were obtained by UPLC-Q-ToF x MS, five tolerant and seven susceptible cultivars. A robust prediction model, was developed that could be used throughout the season to predict the likelihood of new cultivars being susceptible or tolerant towards mango malformation disease. The levels of biomarkers revealed by the models in tolerant and susceptible cultivars were compared and significant differences were observed. These models can serve as an important tool to investigate appropriate cultivars, prior to their introduction to areas prone to the disease.

A total of 100 samples of green coffee (Coffea arabica L.) beans from the major producing regions of Ethiopia were studied using ultra performance liquid chromatography–mass spectroscopy to determine if the phenolic content could be linked to their geographical origins for authentication purposes. Principal component analysis allowed the most discriminating compounds to be identified. Based on their concentrations, 3-O-caffeoylquinic and 4,5-O-dicaffeoylquinic acids were found to be characteristic markers for Northwest and East (Harar) region coffees, respectively. Sub-regional coffee types from West, except Jimma B, could be distinguished by their 3,5-O-dicaffeoylquinic to 4,5-O-dicaffeoylquinic acid concentration ratios, while Yirgachefe coffees from South could be distinguished by their 4,5-O-dicaffeoylquinic to 3,4-O-dicaffeoylquinic acid concentration ratios. Linear discriminant analysis provided a classification model with recognition and prediction abilities of 91% and 90%, respectively, at regional level, and 89% and 86%, respectively, at sub-regional level. This is important for the detection of fraud, including the selling of inferior Ethiopian coffees under the label of the more expensive Harar coffees.

Indigenous Salvia species from southern Africa are popular traditional medicines for the treatment of a variety of conditions. They produce fragrant volatiles that can be isolated as essential oils. Some of these volatile organic compounds may play a role in the biological activities of the extracts. Three indigenous Salvia species, Salvia africana-lutea, S. lanceolata and S. chamelaeagnea, were selected for this study as they are commonly used in traditional medicine in South Africa, and the essential oils from these species have potential for commercialisation. Although some studies have described the essential oil compositions and some biological activities, only single composite samples were used. The aim of this study was to investigate the intra- and interspecies variation of the essential oils, sampled over a wide geographical area and using a representative sample size, to encourage commercialisation of the essential oil. Essential oils were isolated from individual plants using conventional hydrodistillation of the aerial parts, harvested from several localities. Gas chromatography coupled simultaneously to mass spectrometry/flame ionisation detection (GC-MS/FID) was used to identify and quantify the volatile constituents. The essential oils of S. africana-lutea consisted mainly of terpinene-4-ol + β-caryophyllene (1.4 – 29.0%), T-cadinol (1.2 – 20.0%), α-eudesmol (trace – 23.0%) and β-eudesmol (trace – 26.0%), those of S. lanceolata comprised mainly terpinene-4-ol + β-caryophyllene (4.3 – 31.0%), α-humulene (2.3 – 15.0%), bicyclogermacrene (trace – 37.0%) and spathulenol (trace – 25.0%), while the essential oils of S. chamelaeagnea were characterised by δ-3-carene (trace – 18.0%), limonene (1.6 – 36.0%), viridiflorol (9.8 – 61.0%) and 1,8-cineole (not detected – 11.0%). The compounds identified in the essential oils of the three selected Salvia species have been identified in other Salvia essential oils. To add to the novelty of this study, the superior resolving power of two-dimensional gas chromatography was demonstrated through analysis of selected essential oils. Many additional compounds were identified, and previously co-eluting compounds were clearly separated. Chemometric modelling of the GC-MS data using SIMCA P+ 14 software allowed distinct clustering patterns to be discerned. The unsupervised principal component analysis model revealed separate clusters for the three species, confirming substantial chemical differences between their essential oils. Quantitative, rather than qualitative differences were evident when individual essential oil samples representing the same species, were compared. For each species, two chemically distinct groups were observed and unique marker compounds could be identified. This study has contributed detailed information on the major and minor volatile compounds present in the essential oils of the three Salvia species investigated.

The African wild olive (Olea europaea subsp. africana) is traditionally used as a hypotensive agent. Herb-drug interactions may result from the concurrent use of herbal medicines and conventional prescription drugs. This aspect was investigated by determining the effect of the extract on the in vitro intestinal epithelial permeation of selected hypotensive drugs using the Caco-2 cell culture model. The phytochemical profiles of leaf extracts of African wild olive from different localities in South Africa were compared, since efficacy is determined by the chemical composition. Extracts were analysed using ultra-performance liquid chromatography. The oleuropein concentration varied considerably from below the detection limit (4.94 µg/mL) to 59.4 mg/g dry weight. Chemometric models constructed from the aligned chromatographic data indicated only quantitative differences between the profiles. The leaf extract was found to increase the permeability of propranolol in the absorptive direction (Papp = 8.93 × 10−6 cm/s) across Caco-2 cell monolayers, but considerably decreased transport in the secretory direction (Papp = 3.68 × 10−6 cm/s). The permeation of diltiazem was enhanced by the extract in both the absorptive (Papp = 7.33 × 10−6 cm/s) as well as in the secretory direction (Papp = 7.16 × 10−6 cm/s), but a decrease in the efflux ratio was observed. The extract therefore caused a net increase in the transport of both drugs in the absorptive direction due to an inhibition effect on their efflux. This suggests a potential increase in the blood levels of these drugs when taken simultaneously with African wild olive leaf extract, indicating potential adverse effects that must be verified in vivo.

The leaves of Catha edulis Vahl. Endl., known as Khat, are widely used as a “natural amphetamine” stimulant in Africa and in the Arabian Peninsula. In recent years, there has been an increase in the amounts exported to the USA, Australia and Europe. Although the dried, powdered form of the young and mature leaves, as well as samples from different geographical origins, have similar physical appearance, they have not been proven to exhibit equipotent stimulatory activity. In this study, powdered young and mature leaves were differentiated using vibrational spectroscopy, which included mid-infrared (MIR) and near-infrared (NIR) spectroscopy and hyperspectral imaging (HSI), and ultra performance liquid chromatography-mass spectrometry (UPLC–MS), in combination with chemometric data analysis. Samples originating from Ethiopia or South Africa could also be distinguished using chemometric models constructed from HSI data. Principal component analysis (PCA) and orthogonal projection to latent structures discriminant analysis (OPLS-DA) was successfully applied to classify powdered Khat samples according to their geographical origin and level of maturity. The OPLS-DA model constructed from the MIR and UPLC–MS data displayed the ability to clearly distinguish between young and mature leaves, as illustrated by the model statistics ( R 2 X cum and Q 2 cum > 80% and R 2 Y > 90%). Shortwave infrared hyperspectral imaging could distinguish Khat samples from two distinct geographical regions with good model statistics ( R 2 X cum = 0.91 and Q 2 cum = 0.92) and discriminate between the maturity levels ( R 2 X cum = 0.85 and Q 2 cum = 0.80). These models could prove valuable as rapid techniques for identifying confiscated Khat in forensic environments.

The alkaloid compositions of 99 green coffee (Coffea arabica L.) bean samples comprising eight varieties (Harar, Jimma, Kaffa, Wollega, Sidama, Yirgachefe, Benishangul and Finoteselam) from the major production regions of Ethiopia were investigated. High performance liquid chromatography was applied for the simultaneous determination of four coffee alkaloids in the aqueous extracts of the beans. The limits of detection for the method were established as 13 mg kg−1 for trigonelline, 7 mg kg−1 for theobromine, 8.5 mg kg−1 for caffeine and 4 mg kg−1 for theophylline in the dry coffee beans. Theophylline was not detected in any of the samples. The determined concentrations (% w/w dry coffee beans) ranged from 0.98 to 1.32 % for trigonelline, 0.0048 to 0.0094 % for theobromine and 0.87 to 1.38 % for caffeine. The concentrations of the alkaloids varied significantly, depending on the geographical origin of the beans. Theobromine was not detected in coffee beans from the East (Harar coffees), and its absence in samples can be used to ascertain whether the coffee originates from this region. Coffee beans from the Northwest were characterized by higher concentrations of caffeine. Application of linear discriminant analysis provided 75 % correct classification of samples into the respective production regions, with a 74 % prediction success rate. The moderate classification efficiency obtained when using alkaloid data demonstrates the potential of using this class of compounds in discriminant models for determination of the geographical origin of green coffee beans from Ethiopia.

Butein (2′,3,4,4′-tetrahydroxychalcone), a simple chalcone derivative, occurs in many unrelated genera including Butea Dahlia, Coreopsis and Searsia. It is a reputed food additive and a common ingredient of botanicals used in herbal medicine formulations, particularly in Asian countries. Although a simple polyphenol, this molecule exhibits a range of pharmacological properties, most notably acting as a potent protein tyrosine kinase inhibitor and as an antineoplastic agent. Researchers have convincingly demonstrated that butein inhibits the epidermal growth factor receptor in HepG2 cells and the tyrosine-specific protein kinase activities of the epidermal growth factor receptor. In addition, it also exhibits promising anti-inflammatory, antidiabetic, antinephritic, antithrombin, anti-angiogenic and hepatoprotective activities in various animal models. Although this molecule is endowed with an impressive list of biological properties, which have acted as scientific support for its commercialization, there are no review articles that coherently discuss various aspects of this chalcanoid. This review aims to explore the pharmacological relevance of butein, together with its structure–activity relationships and mechanisms of action. In addition, the occurrence, chemical synthesis and biosynthesis of butein are discussed.

The well-known anti-infective properties of propolis are determined by its chemical composition, which in turn is influenced by geographical factors and reflects the botanical diversity in the vicinity of the beehive. Although there are several reports on the anti-infective properties of crude propolis, few are aimed at identifying specific compound(s) responsible for the observed activities. Using South African propolis as an example, the application of high performance thin layer chromatography-bioautography in tandem with mass spectrometry was investigated for the rapid identification of antimicrobial and anti-quorum sensing (anti-QS) compounds. Pinocembrin was found to be responsible for the observed antifungal activity of the propolis against Candida albicans. Three compounds were found to be active against all of the evaluated Gram-positive and Gram-negative bacteria. The identity of the first was confirmed as pinobanksin, one remains unidentified, while the third corresponds to either pinobanksin 3- O -pentanoate or 2-methylbutyrate. The identification of caffeic acid as the anti-QS component was confirmed quantitatively using the violacein inhibitory assay.

The chemical profiles of essential oils isolated from nine populations of Helichrysum splendidum were obtained by gas chromatography. Plants were harvested in both summer and winter seasons in two provinces of South Africa. Essential oils originating from Limpopo Province were characterized by high levels of β-phellandrene, 1,8-cineole, δ-cadinene, α-cadinol, τ-cadinol, and β-pinene. These could be clearly distinguished through multivariate analysis from those collected in Mpumalanga Province. The Mpumalanga oils contained germacrene D, spathulenol and bicyclogermacrene as major constituents. Seasonal variations in the volatile compositions and yields were observed. A prediction model obtained through orthogonal projection to latent structures discriminant analysis was used to compare the essential oil profiles to that of a commercial H. splendidum sample, in addition to those reported for Zimbabwean specimens. One of the specimens from Zimbabwe differed substantially from all the others, indicating the existence of more chemotypes. The structures of the oil-bearing trichomes, as observed on the leaf surfaces using scanning electron microscopy, were investigated and are described for the first time. Since this investigation forms part of an ongoing screening of plants to identify natural alternatives to synthetic fungicides, the essential oils were tested in vitro against several economically important pathogens of fruit. Essential oils from Mpumalanga specimens totally inhibited the growth of Alternaria alternata from avocado and Colletotrichum gloeosporioides isolated from mango at a concentration of 500 μL/L in a toxic medium assay. The presence of high concentrations of germacrene D, spathulenol and bicyclogermacrene probably contributed to the antifungal properties of these essential oils.

Embelin(2,5-dihydroxy-3-undecyl-p-benzoquinone)is known for its potent anthelmintic activity, but also for wound-healing, antidiabetic, anticonvulsant, antitumour, anti-inflammatory, analgesic, hepatoprotective, antioxidant, antibacterial andantispermatogenic activities. A high performance countercurrent chromatography method was developed for the purification of embelin from an extract of the seeds of Embelia schimperi fruit. The optimised solvent system (n-hexane:ethylacetate:ethanol:water (7:3:7:3)) resulted in the isolation of 13.9 mg of embelin, directly from 100 mg of crude extract, in a single step within a short retention time (40 min). Although the compound appeared to be completely pure when analysed by ultra performance liquid chromatography (UPLC) with photo diode array detection (PDA), the purity was established as approximately 90% by UPLC-mass spectrometry (MS). Furthermore, we report the fatty acid composition of the seeds of Embelia schimperi fruit. Nine fatty acids were quantified from the fruit seed extract by gas chromatography-mass spectrometry, with linoleic (46.4%), palmitic (21.5%), and oleic (19.6%) acids making up the largest proportions.

Infection of mango panicles and young leaf shoots by Fusarium results in significantly lower fruit yields. Some mango cultivars are known to be tolerant to blossom malformation, while others are highly susceptible. Previous researchers linked the ability of certain cultivars to confine Fusarium infection to the production of high levels of mangiferin. This study further elucidates the role of phenolic metabolites contributing to tolerance. Phenolic profiles of mature leaf extracts from cultivars with varying degrees of resistance to Fusarium infection were obtained by ultrahigh performance liquid chromatography–time-of-flight-mass detection. Chemometric models constructed from the data revealed a clear distinction between the profiles of tolerant and susceptible cultivars and permitted the identification of biomarkers associated with susceptibility to infection. The presence of elevated levels of mangiferin, maclurin and maclurin O-galloyl-glucoside in the leaves were associated with a higher degree of tolerance. In contrast, high levels of iriflophenone glucosides were linked to increased susceptibility of the cultivars to infection. These models can serve as an important tool to investigate appropriate cultivars, prior to their introduction to areas prone to the disease.

Together with Penicillium moulds, Geotrichum citri-aurantii (sour rot) is a major cause of citrus fruit decay. Fifty-nine commercially available essential oils and some of their major components were screened to determine their effects on the mycelial growth of G. citri-aurantii using toxic medium assays. Nine of these essential oils totally inhibited the mycelial growth of the pathogen at 1000 μl/l. Gas chromatographic analysis revealed the compositions of the most effective oils. Exposure to the vapours of selected essential oils (Thymus vulgaris, Citrus aurantium var. amara, Cymbopogon citratus, Cymbopogon martinii, Origanum vulgare, Geranium graveolens roseum Bourbon) proved fungistatic, rather than fungicidal, towards the pathogen. ‘Valencia’ oranges, inoculated with G. citri-aurantii, were treated with the most promising botanicals. Essential oils (1000 μl/l) of C. citratus, C. martinii, O. vulgare and G. graveolens roseum Bourbon, incorporated into coating or applied as a curative dip, resulted in a drastic reduction in decay when compared to the negative control. No physiological breakdown of the fruit was evident at this concentration. C. citratus (lemongrass) was selected as the most cost-effective option for control of G. citri-aurantii. Previous commercial trials indicated the protective properties of Mentha spicata essential oil against Penicillium digitatum. To develop an effective multi-target protection product against G. citri-aurantii, P. digitatum and Penicillium italicum, essential oil of C. citratus was combined with that of M. spicata. A toxic medium, containing both essential oils, each at 750 μl/l, totally controlled all three pathogens. Although individual essential oil-amended coatings have previously been applied for postharvest control, this study proposes a mixture of these essential oils for control of two serious citrus pathogens (G. citri-aurantii, P. digitatum), in addition to P. italicum.

Quorum sensing controls bacterial pathogenesis and virulence, hence, interrupting this system renders pathogenic bacteria non-virulent, and presents a novel treatment for various bacterial infections. In the search for novel anti-quorum sensing (AQS) compounds, 14 common culinary herbs and spices were screened for potential antipathogenicity activity against Chromobacterium violaceum ATCC 12472. Extracts of Glycyrrhiza glabra (liquorice), Apium graveolens (celery), Capsicum annuum (cayenne pepper) and Syzygium anisatum (aniseed) demonstrated good AQS potential, yielding opaque halo zones ranging from 12&ndash, 19 mm diameter at sub-minimum inhibitory concentrations (0.350&ndash, 4.00 mg/mL). For the same species, the percentage reduction in violacein production ranged from 56.4 to 97.3%. Zones with violacein inhibitory effects were evident in a celery extract analysed using high performance thin layer chromatography-bio-autography. The major active compound was isolated from celery using preparative-high performance liquid chromatography-mass spectrometry and identified using gas chromatography-mass spectrometry (GC-MS) as 3-n-butyl-4,5-dihydrophthalide (sedanenolide). Potent opaque zones of inhibition observed on the HPTLC-bio-autography plate seeded with C. violaceum confirmed that sedanenolide was probably largely responsible for the AQS activity of celery. The bacteriocidal properties of many herbs and spices are reported. This study, however, was focussed on AQS activity, and may serve as initial scientific validation for the anti-infective properties ascribed to several culinary herbs and spices.

Lippia species are widely used as traditional remedies by many South African communities. The identification of Lippia spp. indigenous to South Africa is currently based on the morphology and geographical origin of the specimen. However, morphological similarities are evident and due to sympatric distributions, different species may co-occur in the same natural environment, thereby presenting difficulties in the taxonomic delimitation of these taxa. In this paper, gas chromatography–mass spectrometry (GC–MS) and vibrational spectroscopic analyses were used to investigate the chemotaxonomic differentiation of four Lippia species ( L. javanica , L. scaberrima , L. rehmannii and L. wilmsii ), based on the essential oil composition. The results demonstrate that multivariate classification of chromatographic data enabled separation of Lippia oils into three distinct clusters representing L. scaberrima , L. rehmannii and L. javanica . With the aid of chemometric algorithms, it was also possible to use both mid infrared (MIR) and near infrared (NIR) spectroscopy for a clear distinction of the Lippia spp., with results comparable to those obtained by GC–MS. Orthogonal projections to latent structures (OPLS) presented a better classification algorithm than principal component analysis (PCA), in both GC–MS and spectroscopy analyses. Chemical variations within the Lippia spp. complex were evident, particularly for L. javanica and L. scaberrima , which exhibited significant intra-species variation.

In this study, near-infrared (NIR) spectroscopy, in combination with chemometrics, was used as a rapid tool for determining if exposure to contamination from mine tailings influences the matrices of the specimens, compared to those from natural populations. Principal component analysis (PCA) plots were made from the chemometric models obtained to establish if season of harvest, geographical origin, and level of soil contamination play a determining role in the chemical profiles of the individual specimens harvested from mine sites or natural populations. The random distribution on PCA score plots corroborated the intraspecies variation of Lippia scaberrima previously observed by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS) essential oil profiles. Clustering according to the season and origin of the individual plants confirmed that the geographic location and the season of harvest influence the chemical profiles of L. scaberrima. The NIR data could not be correlated with the level of soil contamination to which the specimens were exposed. The PCA scores and loadings plots obtained from NIR data of Searsia pendulina suggest that the species is tolerant to pollution from mine tailings. Although separation was obtained in a three-component PCA model between specimens sampled during different seasons, some clustering was observed by specimens from the same geographical origin.

The biological properties of verbascoside are numerous and include antimicrobial activities. As part of a drive to identify alternatives to synthetic fungicides for crop protection, this study was aimed at investigating methods of preparing verbascoside-rich plant extracts from viable sources of the compound and monitoring its stability under various conditions. Leaf extracts of Lippia javanica Spreng. and Lantana camara Linne (Verbenaceae) were partially purified using column chromatography and high speed centrifugal countercurrent chromatography, the latter yielding fractions with higher purity (71%) than those from a single column chromatographic separation (38–44% pure). Verbascoside remained stable upon heating, but was completely decomposed after four hours exposure of the extract to sunlight. Compared to the other storage conditions, the compound was best preserved in a dry form in the dark. Analysis by high performance liquid chromatography revealed that the verbascoside content of plant parts of L. camara from natural populations was highly variable, both within and between populations. However, several specimens produced high levels of the compound (Hazyview: Plant 3 (83.0 mg/g dry weight), Magoebaskloof 2: Plant 5 (64.8 mg/g) and White River: Plant 2 (64.0 mg/g)), suggesting that L. camara is an excellent source of verbascoside. Extracts of the plant displayed effective in vivo inhibition of Penicillium digitatum on oranges.

Introduction Sceletium tortuosum is the most sought after species of the genus Sceletium and is commonly included in commercial products for the treatment of psychiatric conditions and neurodegenerative diseases. However, this species exhibits several morphological and phytochemical similarities to S. crassicaule. Objectives The aim of this investigation was to use ultrahigh-performance liquid chromatography (UPLC) and hyperspectral imaging, in combination with chemometrics, to distinguish between S. tortuosum and S. crassicaule, and to accurately predict the identity of specimens of both species. Methods Chromatographic profiles of S. tortuosum and S. crassicaule specimens were obtained using UPLC with photodiode array detection. A SisuChema near infrared hyperspectral imaging camera was used for acquiring images of the specimens and the data was processed using chemometric computations. Results Chromatographic data for the specimens revealed that both species produce the psychoactive alkaloids that are used as quality control biomarkers. Principal component analysis of the hyperspectral image of reference specimens for the two species yielded two distinct clusters, the one representing S. tortuosum and the other representing S. crassicaule. A partial least squares discriminant analysis model correctly predicted the identity of an external dataset consisting of S. tortuosum or S. crassicaule samples with high accuracy (>94%). Conclusions A combination of hyperspectral imaging and chemometrics offers several advantages over conventional chromatographic profiling when used to distinguish S. tortuosum from S. crassicaule. In addition, the constructed chemometric model can reliably predict the identity of samples of both species from an external dataset. Copyright © 2013 John Wiley & Sons, Ltd.

The alkaloids of Sceletium tortuosum (Mesembryanthemaceae) exhibit important pharmacological properties and are used for the treatment of psychiatric and psychological conditions, including depression, anxiety, drug dependence, bulimia and obsessive-compulsive disorder. The all-liquid technique of high-speed countercurrent chromatography provides an excellent tool for the rapid isolation of these alkaloids in high yields.

The development of natural crop protective products as alternatives to synthetic fungicides is currently in the spotlight. In vitro experiments are valuable precursors to more costly in vivo trials, allowing the identification of effective essential oils and establishing the concentrations required for inhibition of a specific, or spectrum of decay pathogens. In this study, the antifungal properties of eighteen essential oils were evaluated in vitro by addition to the fungal growth medium of five pathogens ( Lasiodiplodia theobromae , Colletotrichum gloeosporioides , Alternaria citrii , Botrytis cinerea and Penicillium digitatum ) isolated from mango, avocado, citrus, grapes and cactus pear. The inhibitory properties of some of the major compounds of the oils, identified and quantified by gas chromatography–mass spectroscopy and gas chromatography–flame ionization detection were also determined. Most of the oils were selected on the basis of commercial availability and for containing a predominant compound. Visual inspection of fungal growth was done and the lowest concentration where fungal growth was completely inhibited on all replicates was recorded. Thyme oil proved to be the most effective inhibitor, totally inhibiting all of the pathogens tested at concentrations of 1000 μl/l and lower, with the exception of a resistant Penicillium strain. Cinnamon oil, rich in eugenol (81.2%), demonstrated good fungicide potential, while the carvone-rich oils displayed promising activity against the citrus pathogens. Oils characterized by high concentrations of S-carvone were less effective than those containing the R-enantiomer. Essential oil of Lippia citriodora was active against all of the pathogens, excluding L. theobromae from avocado. These essential oils, applied alone or in combination, are good candidates for further in vivo testing and for investigations concerning their modes of action.

Lippia scaberrima Sond. (Verbenaceae) is an aromatic shrub, indigenous to South Africa. A camphorous essential oil was obtained from bulk aerial parts of L. scaberrima by steam distillation. Gas chromatography with flame ionization detection revealed that d-limonene, 1,8-cineole and (R)-(-)-carvone were the main oil constituents. Strong in vitro antifungal activity of the essential oil was observed against common postharvest spoilage pathogens of mango, avocado and citrus fruit. R-carvone was found to be largely responsible for this antifungal activity. These results were confirmed by semi-commercial and commercial trials using fruit treated with coatings, amended with L. scaberrima and Mentha spicata (spearmint) essential oil. The control treatments were done using standard commercial fungicide applications, while the experimental treatments all consisted of coating amended with the oil or single terpenoid constituents, in the absence of synthetic fungicides. Effective disease control was obtained using all of the amended treatments. Quality parameters measured indicated that the overall quality of the fruits was maintained. Essential oil amended coatings could eliminate environmentally harmful toxic waste originating from standard packhouse procedures. Alternatively, the use of essential oils alone or in combination with synthetic fungicides, could lengthen the useful lifespan of existing fungicides.

Proliferation of fungal pathogens, such as Mycogone perniciosa , can severely affect the yields of cultivated mushrooms, including that of the button mushroom, Agaricus bisporus. A reduction in the number of fungicidal products approved for commercial application is currently providing new challenges to the mushroom industry . Forty essential oils, seven pure terpenoids and one phenylpropanoid were screened in vitro to determine the abilities of these substances to inhibit the growth of M. perniciosa . The fungal growth medium of both A. bisporus and M. perniciosa was supplemented with each test substance at a concentration of 50 μL/L. Ten essential oils were further investigated at lower concentrations ranging from 5 to 40 μL/L. The main components of these oils were determined by GC–FID and GC–MS. Lemon verbena ( Lippia citriodora ), lemongrass ( Cymbopogon citratus ) and thyme ( Thymus vulgaris ) oils were found to substantially inhibit the growth of the pathogen, while demonstrating lower toxicity towards A. bisporus than any of the other oils tested. A preliminary in vivo trial using M. perniciosa -inoculated casings revealed that the preventative use of lemon verbena or thyme oils was able to control the development of the disease. A commercial trial using these oils, as well as two of their main components (nerol and thymol), at a concentration of 40 μL/L, revealed that none of these treatments were detrimental to the growth of the A. bisporus and an overall yield similar to that following application of a commercial fungicide (Chronos 450 SC) was obtained. These results suggest that essential oils or mixtures of selected pure components of essential oils may in future find application in button mushroom production, either as a substitute for synthetic fungicides or as an additional protective measure.

Mycobiocides are attracting research interest worldwide as possible postharvest pathogen control measures to replace synthetic fungicides. In this study, the application of two essential oils as fungicides was evaluated. Initially, the in vitro antifungal effects of Lippia scaberrima essential oil and three of the major oil components, ( d )-limonene, R-(−)-carvone, and 1,8-cineole, as well as that of S-(+)-carvone, were investigated against Colletotrichum gloeosporioides , Lasiodiplodia theobromae , and an Alternaria isolate. The oil and terpenoids caused significant inhibition of the mycelial growth of all the pathogens when applied at a concentration of 2000 μL L −1 . The most potent volatile component of L . scaberrima essential oil, able to inhibit all the pathogens tested, proved to be R -(−)-carvone. The efficacy of the essential oil (1000 and 2000 μL L −1 ) incorporated into the commercial coating was confirmed on fruit inoculated with two of the pathogens. A simulated export trial was done using Lippia essential oil, in addition to Mentha spicata (spearmint) essential oil, as supplements for fruit coatings. Results indicate that essential oils rich in R-(−)-carvone could be valuable alternatives to synthetic fungicides for the postharvest management of avocado fruit. The combination of essential oils with a commercial coating, acceptable to the organic market, offers additional protection to this vulnerable commodity.

The mango gall fly (Procontarinia) is a growing concern in many countries that import mango trees. Mangoes flush (produce opening buds) twice a year: once in spring, and the main flush, which occurs in early autumn flush and corresponds to the photoperiod necessary for the gall fly to emerge. Gall flies attack only very young mango flush leaves. Three cultivars displaying varying susceptibility were used in this study: Heidi, which typically is heavily infected; Keitt, which displays antixenosis properties; and Sensation, which is resistant to gall fly attack. Headspace profiles of the three cultivars were obtained over two full growing seasons. It was found that flush leaves emit higher levels of volatile organic compounds than mature leaves. Volatile emissions peaked during the main flush, after which they declined as the tree went into the winter dormant period. The levels of α- and β-pinene increased in gall fly-susceptible cultivars as the season progressed, while very low levels of these terpenes were emitted by resistant cultivars. The changes in the profiles of these emissions suggest that α- and β-pinene may be linked to gall fly susceptibility. In addition, chemometric analysis confirmed the correlation between volatile emissions and gall fly susceptibility. Copyright © 2010 John Wiley & Sons, Ltd.

Lippia rehmannii H.Pearson (Verbenaceae) is an aromatic bush, indigenous to the northern parts of South Africa. As far as could be ascertained, the essential oil composition has not been previously reported and forms the subject of this investigation. Aerial parts of the shrub were collected from two localities in Gauteng, South Africa, and the isolated essential oils were analysed by gas chromatography. Citral, a mixture of the E- and Z-isomers, was found to be the main constituent of the oils, while borneol, camphor, neryl acetate, isocaryophyllene, p -cymene, β-caryophyllene and β-caryophyllene oxide were other major compounds present. Oil compositions, within and between the two localities, did not differ significantly. The in vitro antifungal activity of L. rehmannii essential oil was compared to that of Cympopogon citratus (lemongrass) and pure citral, against a number of pre- and postharvest fungal food pathogens. At a concentration of 3000 µL/L, lemongrass oil and pure citral caused complete growth inhibition of all the pathogens tested. Lippia rehmannii , containing less citral than lemongrass oil, was effective at this concentration against the majority of pathogens, but only partially restricted the growth of Lasiodiplodia theobromae and Botrytis cinerea. This finding suggests that citral may be largely responsible for the observed antifungal activities. Essential oil from L. rehmannii appears to be a good candidate for the in vitro control of Fusarium oxysporum and Rhizoctonia solani and application of these oils in the field should be investigated.

A new approach to the control of postharvest pathogens, while maintaining fruit quality, has been implemented by the application of essential oil amended coatings to citrus. This approach eliminates the need for synthetic fungicides, thereby complying with consumer preferences, organic requirements and reducing environmental pollution. In vitro studies indicated that the essential oils and some of the terpenoid components tested were active against Penicillium digitatum. In a series of subsequent semi-commercial and commercial trials, Mentha spicata and Lippia scaberrima essential oils, as well as pure (d)-limonene and R-(−)-carvone were incorporated into a variety of commercial citrus coatings. These amended coatings were applied postharvest to ‘Tomango’ oranges in the absence of the standard fungicide dip. Excellent disease control was achieved with the amended coatings, while measured quality parameters indicated that overall fruit quality was maintained. Moreover, moisture loss was decreased significantly in fruit treated with essential oil enriched coatings. The efficacy of amended coatings as a viable alternative or supplement to existing fruit protection strategies was demonstrated in a commercial trial.

Introduction . Penicillium digitatum is a commercially important postharvest pathogen of citrus that is responsible for significant annual global losses. Strains of the fungus, which exhibit strong resistance to widely used synthetic fungicides, are of major concern to the industry. The aim of the study was to investigate the antifungal activities of polar extracts and compounds from Lippia species, indigenous to South Africa, against a Guazatine® -resistant strain of P. digitatum. Materials and methods . In vitro tests were done by incorporating the compounds and plant extracts into Malt Extract Agar at concentrations ranging from (0.2 to 1.0) mg·mL–1 . An in vivo (curative) assay was conducted using the checkerboard technique on ‘Valencia’ oranges. Results and discussion . A strong correlation between the in vitro and in vivo results was observed. All the compounds and extracts were able to inhibit fungal growth at concentrations above 0.6 mg·mL–1 . Verbascoside was the most active compound, while extracts of Lippia javanica and Lippia rehmannii caused significant inhibition of mycelial growth. The observed activity was largely ascribed to the presence of verbascoside in the plant extracts. Conclusion . Polar extracts of Lippia species have potential as environmentally friendly alternatives for the control of P. digitatum on citrus.

Lippia scaberrima , an aromatic shrub with medicinal properties, is indigenous to southern Africa. Essential oil obtained from aerial plant parts was assessed in vitro and in vivo for antifungal activity against Botryosphaeria parva and Colletotrichum gloeosporioides isolated from mango fruit. Exposure to oil vapour for 2 and 4 days caused inhibition of mycelial growth of both isolates. Three major terpenoids identified in the oil, limonene, R -(−)-carvone, and 1,8-cineole, as well as S -(+)-carvone, were individually evaluated in vitro . The two enantiomers of carvone, along with L. scaberrima oil, were found to have the highest fungistatic activity. Oil and carvone enantiomer fungicidal activities were less pronounced. The use of commercial wax coatings enriched with essential oils led to reduced fungal infection by both pathogens. Results of the in vitro and preliminary in vivo studies suggest that employing L. scaberrima oil to control postharvest pathogens is worthy of further investigation.

Lippia scaberrima (Verbenaceae) is an aromatic, medicinal shrub which is indigenous to southern Africa. Quantitative and qualitative analyses of the essential oil were conducted using gas chromatog...

Hypoxis species (Hypoxidaceae) are amongst the most widely used medicinal plants in southern Africa. Although the phytochemistry of Hypoxis hemerocallidea has been extensively investigated, little is known regarding the secondary metabolites of the other indigenous species, including Hypoxis colchicifolia and Hypoxis galpinii. Two new phenolic glycosides, 3-hydroxy-4-O-β-d-glucopyranosylbenzaldehyde and 1,5-bis(3,4-dihydroxyphenyl)-1,2-dihydroxy-4-pentyne-2-p-coumaroyl-β-d-glucopyranoside were isolated from corms of H. colchicifolia and H. galpinii, respectively. The norlignan glycosides (hypoxoside, dehydroxy hypoxoside and bis-dehydroxy hypoxoside) were isolated from H. colchicifolia for the first time, using high performance countercurrent chromatography and elucidated by 1D and 2D NMR as well as high resolution MS. In addition, geraniol glycoside and β-sitosterol, previously described in Hypoxidaceae, were isolated from the same species. The presence of hypoxoside in all three species investigated indicated that the interchangeable use of Hypoxis species by communities has some merit. Establishing the biological properties of the new constituents will provide more insight into the medicinal value of the genus.

The leaves of Leucosidea sericea (Rosaceae) are used medicinally by some indigenous South African people as a vermifuge and astringent. No information on the biological activity and phytochemistry of the plant could be found in the literature. Bioassay-guided fractionation was used to identify the active compound. Partial purification of the petroleum ether extract of the leaves and flowers was followed by fractionation using chromatographic methods. This process yielded the Phloroglucinol derivatives, aspidinol and desaspidinol, which were previously reported to be present in a Dryopteris species. Aspidinol was further isolated and structurally elucidated. This is the first report of the presence of these compounds in Leucosidea sericea. The disk diffusion method used in our study, indicated that the plant has antimicrobial activity against Staphylococcus aureus , Bacillus subtilis and Candida albicans .

Sceletium tortuosum is an indigenous South African plant that has traditionally been used for its mood-enhancing properties. Recently, products containing S. tortuosum have become increasingly popular and are commonly administered as tablets, capsules, teas, decoctions, or tinctures, while traditionally the dried plant material has been masticated. This study evaluated the in vitro permeability of the four major S. tortuosum alkaloids (i.e., mesembrine, mesembrenone, mesembrenol, and mesembranol) across porcine intestinal, sublingual, and buccal tissues in their pure form and in the form of three different crude plant extracts, namely water, methanol, and an acid-base alkaloid-enriched extract. The permeability of mesembrine across intestinal tissue was higher than that of the highly permeable reference compound caffeine (which served as a positive control for membrane permeability) both in its pure form, as well as in the form of crude extracts. The intestinal permeability of mesembranol was similar to that of caffeine, while those of mesembrenol and mesembrenone were lower than that of caffeine, but much higher than that of the poorly permeable reference compound atenolol (which served as a negative control for membrane permeability). In general, the permeabilities of the alkaloids were lower across the sublingual and the buccal tissues than across the intestinal tissue. However, comparing the transport of the alkaloids with that of the reference compounds, there are indications that transport across the membranes of the oral cavity may contribute considerably to the overall bioavailability of the alkaloids, depending on pre-systemic metabolism, when the plant material is chewed and kept in the mouth for prolonged periods. The results from this study confirmed the ability of the alkaloids of S. tortuosum in purified or crude extract form to permeate across intestinal, buccal, and sublingual mucosal tissues. http://www.thieme.com/books-main/biochemistry/product/3494-planta-medica http://dx.doi.org/10.1055/s-0031-1280367 The authors would like to thank the National Research Foundation (South Africa) for providing financial support for the study.

Lippia scaberrima Sond. is an aromatic shrub of semi-arid, summer-rainfall grassland and occurs in the northern provinces of South Africa. The plant is a common natural coloniser of gold mine tailings and contaminated soils, and is one of a number of similar species that has been tested for use in tailings stabilisation. Mine rehabilitation strategies worldwide involve the use of native and locally tolerant plants. Where such plants have commercially valuable attributes, their use to stabilise contaminated soils and tailings also provides opportunities for local beneficiation and the development of new industries post- mining. The production of aromatic plants is considered a particularly safe option for mine waste since they are generally unpalatable to herbivores and the steam distillation methods used for essential oil isolation yield products free from metal and radioactive contaminants. In the initial part of this study the essential oil of bulk samples of L. scaberrima growing in a natural habitat was found to exhibit strong in vitro antifungal activity against several commercially important fruit post- harvest spoilage pathogens. Gas chromatography with flame ionisation detection (GC-FID) analysis of the oil identified limonene, 1,8-cineole and R-carvone as the main constituents. The antifungal activity of the oil was attributed to the presence of R-carvone. These results were confirmed by several semi-commercial and commercial trials on mango, avocado and citrus fruit. The potential application of L. scaberrima essential oil, rich in R-carvone, as a post-harvest fungicide of fruit, may necessitate the large-scale production of the oil. However, essential oil profiles of Lippia spp. in general have been shown to exhibit high intraspecific variability due to genetic differences. In this investigation the essential oil profiles of L. scaberrima specimens from populations growing in mine- contaminated substrata were compared to those of specimens growing in uncontaminated soils to identify a R-carvone chemotype selected for the harsh growing conditions existing in and around mine tailings. The findings indicate that L. scaberrima does not bioaccumulate metals present in contaminated soils, and essential oils prepared using steam distillation were free of metals and uranium.