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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.

Many mines in South Africa were inappropriately closed and left unattended during the last century. These old mines are potential sources of environmental pollution and may pose a health risk to local populations, since the surrounds contain elevated levels of toxic elements. Soil from the old Edendale lead mine property in Mamelodi Extension 11, east of Pretoria, which was suspected to be contaminated with lead, was analysed. The mine, which primarily extracted galena, was decommissioned in 1938. During this study, the old mine property and surrounds were screened for zinc and lead using a field-portable X-ray fluorescence (pXRF) spectrometer. The metal concentrations, which ranged from 18 to 7 300 mg/kg for zinc and from 50 to 21 000 mg/kg, for lead, were plotted together with the GPS coordinates to produce a concentration distribution map for lead and zinc. This map revealed three anomalies of unacceptably high concentrations, possibly corresponding to areas where ore had been piled or dumped to waste from the old mine. Thirty-six of the soil samples that were analysed by pXRF on site were selected and analysed in the laboratory using inductively coupled plasma-optical emission spectrometry (ICP-OES) for verification purposes. The zinc and lead concentrations obtained from the two analytical methods were compared using linear regression analysis. Excellent correlation was obtained between the results from the two methods (r² = 0.99 for zinc and r2 = 0.95 for lead).

Leaves of khat ( Catha edulis ) are masticated to elicit their psycho-stimulating properties, resulting from the presence of the phenylpropylamino alkaloids. The determination of these alkaloids is important in pharmacological, phytochemical, forensic and law enforcement environments. In this study, the use of strong cation exchange-solid phase extraction (SCX-SPE) was investigated as an alternative means of sample purification prior to the determination of cathinone, cathine and norephedrine by reversed phase (C 18 ) high performance liquid chromatography (HPLC). Extraction parameters for SCX, including loading capacity and washing solvents, were established. An existing liquid-liquid extraction (LLE) method was improved in terms of recoveries obtained, by using ethyl acetate as extractant. For pure standards of the khat alkaloids, recoveries ranged from 83 to 97%. Preconcentration, using a Genevac evaporator after the addition of acidified water to the sample, restricted analyte losses when compared to concentration under nitrogen. Although comparable recoveries were obtained when preconcentration was achieved in the presence of acidified water by rotary evaporation, this method is not suitable for large sample numbers. Best recoveries, ranging from 94 to 102%, were obtained by SCX from spiked samples. Although the extraction efficiencies of LLE were lower (87-90%), LLE yielded less complex chromatograms, indicating a purer extract. KEY WORDS : Khat alkaloids, Solid phase extraction, Liquid-liquid extraction, HPLC, Genevac Bull. Chem. Soc. Ethiop. 2015 , 29(3), 331-339. DOI: http://dx.doi.org/10.4314/bcse.v29i3.1

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.

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.

Chemistry for first year students has been identified by Tshwane University of Technology as one of the subjects with a low pass rate. It is apparent that students often memorize formulae and definitions, without understanding the underlying concepts required to work with abstract units of measure. We have found that the majority of students at this university are unable to balance reaction equations satisfactorily. They are also unable to predict the reaction yield, or identify limiting reagents. It is imperative that these and other related problems are overcome before any meaningful change to the high failure rate at first year level will be realized. All conventional forms of lecture presentation failed to make any significant impact on the success rate. Structured worksheets were developed and used, together with tactile models, to address the problems and the initial findings showed a marked improvement. It was discovered that the students’ problems originated from their inability to understand the meaning of subscripts and coefficients in chemical equations. The worksheets and the impact they have made on the students’ understanding of stoichiometry are shared in this paper.Keywords: Stoichiometry, limiting reagent, worksheets, tactile models

Lippia javanica and Lippia scaberrima are used as herbal remedies and are commercially traded as health teas in southern Africa under the brands “Mosukujane” and “Musukudu”, respectively. This study evaluates the relationship between the presence of phenolic compounds and the antioxidant activities of infusions prepared from four Lippia species ( L. javanica , L. scaberrima , L. rehmannii and L. wilmsii ) indigenous to South Africa. The antioxidant activities of the infusions, determined by the 2,2-diphenylpycrylhydrazyl (DPPH) method, were also compared to those of popular black, green and herbal tea brands. Of the four indigenous species, infusions of L. javanica and L. wilmsii exhibited the highest antioxidant activities (EC 50 : 358 and 525 µg/ml, respectively) and contained the most phenolic compounds (14.8 and 14.5 mg/ml of dry weight gallic acid equivalent, respectively). Antibacterial activities of methanolic extracts of the four Lippia species were determined against four human pathogens ( Staphylococcus aureus , Enterococcus faecalis , Escherichia coli and Pseudomonas aeruginosa ). The extract of L. javanica was the most active against all the pathogens tested. Those Lippia species ( L. javanica and L. wilmsii ) previously reported to produce higher levels of the pharmacologically active phenylethanoid glycosides verbascoside and isoverbascoside, portrayed stronger antioxidant and antibacterial activities. This study gives credence to the use of infusions of these Lippia species for their general health benefits.

Anecdotal evidence indicates that Sceletium tortuosum has been used as a psychoactive preparation for several centuries. The psychological activity is attributed to the production of mesembrine-type alkaloids (mesembrenol, mesembranol, mesembrenone and mesembrine) by the plant. This investigation was aimed at developing validated reversed phase ultra performance liquid chromatography with photodiode array detector (RP‐UHPLC PDA) and gas chromatography coupled to mass spectrometry (GC–MS) methods for quantitative assessment of mesembrine-type alkaloids in S. tortuosum raw materials and products. Both methods were validated for linearity, repeatability and recovery. Limits of detection (LOD) and limits of quantification (LOQ) for the alkaloids were also established. The LOD range for the RP‐UHPLC PDA analysis of compounds was 0.91–1.21 μg ml − 1 , while the LOQ range was 2.72–3.71 μg ml − 1 . For GC–MS analysis, the LOD and LOQ ranges for the compounds were 11.78–22.76 μg ml − 1 and 35.34–68.29 μg ml − 1 respectively. Regression analyses indicated good linear relationships for the investigated compounds. The regression coefficients ( R 2 ) from RP‐UHPLC PDA analyses ranged from 0.9977 to 0.9991, while those derived from GC–MS analyses were within the range of 0.9979 to 0.9995. Intra- and inter-day precision values for all the alkaloids were below 3.44% for RP‐UHPLC PDA and below 3.15% for GC–MS analysis, indicating excellent repeatability. Percentage recovery ranges for the four alkaloids as determined by RP‐UHPLC PDA and GC–MS analyses ranged from 80.00 to 89.83% and from 80.77 to 90.00%, respectively. Plots of RP‐UHPLC PDA data of selected raw materials and products versus GC–MS data, showed good linear correlation ( R 2 = 0.9820–0.9987). The chromatographic methods were found to be repeatable, precise and appropriate for use in the routine quality control of the psychoactive alkaloids in S. tortuosum raw materials and products.

Lippia javanica (N.L.Burm.) Spreng. is an aromatic, multipurpose medicinal plant from which a number of volatile compounds have been identified, together with toxic triterpenoids and iridoid glycosides. Two additional phenylethanoid glycosides, verbascoside and isoverbascoside, were isolated from L. javanica and characterized. High performance liquid chromatography analyses of polar extracts of three other Lippia species (L. scaberrima, L. rehmannii and L. wilmsii), indigenous to South Africa, revealed the presence of both isomers. When compared to the other indigenous Lippia species, the leaves of L. javanica were found to contain the highest concentrations of both isomers. In addition, the intraspecies variation of the verbascoside/isoverbascoside content of L. javanica, harvested from the same and different localities, was investigated. The concentrations of the two phenylethanoids remained fairly consistent within and between different populations, even when geographically separated. While these compounds are produced by many genera, they may now be added to the list of iridoid glucosides employed as chemotaxonomic markers for Lippia species.

Listeria monocytogenes is a Gram-positive bacterium, able to survive and grow in water, soil, agricultural products, various foods and the foodprocessingenvironment.Theubiquitousnatureoftheorganism,coupledwithitsabilitytocolonisefood-processingsurfacesbyformingbiofilms,causes it to be of a major concern to the industry. Increased foodborne pathogen resistance and negative consumer perceptions regarding the use of synthetic bacteriocides, has resulted in natural antimicrobials being sourced from the plant kingdom. The listerial antibiofilm activities of Syzygium aromaticum (clove),Menthaspicata(spearmint),LippiarehmanniiandCymbopogoncitratus(lemongrass)essentialoilsandtheirmajorcomponentswereevaluated using the crystal violet assay and confocal scanning laser microscopy. Listerial biofilms treated with S. aromaticum or M. spicata essential oils, or the pure compounds nerol and citral, exhibited a similar biofilm biomass to the positive control. However, the essential oils of lemongrass, L. rehmannii, eugenol and R-carvone caused biofilm enhancement, rather than inhibition. L. rehmannii and lemongrass essential oils did not display any antibiofilm properties. Results obtained were confirmed by microscopic observations indicating either a reduction (inhibition) or an increase (enhancement) in biofilm biomass when exposed to the essential oils or pure compounds. The present study revealed that M. spicata and S. aromaticum essential oils as well as pure citral and nerol are good candidates for further development of ecofriendly disinfectants. © 2010 SAAB. Published by Elsevier B.V. All rights reserved.