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Neurotrophins such as nerve growth factor (ngf) and brain-derived neurotrophic factor (bdnf) play important roles in the central nervous system. They are potential therapeutic drugs for the treatment of neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease. In this study, we investigated the neurotrophic properties of triterpenes isolated from fruiting bodies of Laetiporus sulphureus and a mycelial culture of Antrodia sp. MUCL 56049. The structures of the isolated compounds were elucidated based on nuclear magnetic resonance (NMR) spectroscopy in combination with high-resolution electrospray mass spectrometry (HR-ESIMS). The secondary metabolites were tested for neurotrophin (ngf and bdnf) expression levels on human astrocytoma 1321N1 cells. Neurite outgrowth activity using rat pheochromocytoma (PC-12) cells was also determined. Twelve triterpenoids were isolated, of which several potently stimulated the expression of neurotrophic factors, namely, ngf (sulphurenic acid, 15α-dehydroxytrametenolic acid, fomefficinic acid D, and 16α-hydroxyeburicoic acid) and bdnf (sulphurenic acid and 15α- dehydroxytrametenolic acid), respectively. The triterpenes also potentiated ngf-induced neurite outgrowth in PC-12 cells. This is, to the best of our knowledge, the first report on the compound class of lanostanes in direct relation to bdnf and ngf enhancement. These compounds are widespread in medicinal mushrooms; hence, they appear promising as a starting point for the development of drugs and mycopharmaceuticals to combat neurodegenerative diseases. Interestingly, they do not show any pronounced cytotoxicity and may, therefore, be better suited for therapy than many other neurotrophic compounds that were previously reported.

This study evaluated antibacterial activity of Chrysanthemum cinerariaefolium (pyrethrum) flower dichloromethane crude extract, fractions and isolated compounds; pyrethrin II, jasmolin I and cinerolone against methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Staphylococcus aureus and Shigella sonnei. The isolated compounds were obtained by carrying out column chromatography on dichloromethane extract and purifying the fractions using preparative High Perfomance Liquid Chromatography (HPLC). The structures of the isolated compounds were elucidated using 1D and 2D NMR. The bioactivity of crude extract, fractions and isolated compounds were determined using disc diffusion assay at a concentration of 100 mg/mL. The MIC and MBC were determined using microdilution method. The bioassay results showed that individually isolated compounds were not active on all the micro-organisms except Jasmolin I which showed slight activity on P. aeruginosa with 7.7±0.6 mm. There was significant difference in the activity of the isolated compounds as a mixture and the activity of individual compounds on MRSA, S. aureus, P. aeruginosa, with P= 0.01, P= 0.0002, P= 0.0007 respectively (α =0.05, Tukey’s test). Isolated compounds and isolated compounds as a mixture in a ratio of (1:1:1) were not active on S. sonnie. Those fractions and isolated compounds which caused inhibition zones of above 10 mm were subjected to MIC and MBC. The lowest MIC and MBC observed was for fraction 3 against MRSA which were 6.5 and 12.5 mg/mL respectively. The compound mixture had MIC and MBC of 25 and 50 mg/ml respectively against P. aeruginosa. Key words: MIC (minimum inhibitory concentration), MBC (minimum bacteriostatic concentration), bioassay, Chrysanthemum cinerariaefolium, Jasmolin, Pyrethrin II, Cinerolone.

Fungal endophytes are regarded as inexhaustible sources of pharmaceuticals and agrochemicals with profound antibacterial, anticancer or antifungal activities. Diaporthe sp., an endophytic fungus residing in medicinal plant S. cordatum, showed a good antagonism against bacterial pathogens of beans; Pseudomonas syringae pv phaseolicola (Psp) and Xanthomonas axonopodis pv phaseoli (Xap), with zones of inhibitions of 14.00 ± 1.15 and 17.00 ± 0.58 mm against the test organisms respectively. Large scale fermentation of Diaporthe sp. was performed on rice media after which ultrasonic extraction on methanol was done to yield methanol crude extract. Methanol crude extract was then partitioned between hexane and ethyl acetate to yield their respective crude extracts. Ethyl acetate fraction of Diaporthe sp. yielded one new naphthalene derivative compound which was accorded IUPAC name as 3-methoxy-5-methylnaphthalene-1, 7-diol after series of purifications on column chromatography as well as preparative high-performance liquid chromatography (pHPLC). Structure determination of isolated compounds was performed on 1D and 2D Nuclear Magnetic Resonance (NMR) spectroscopy experiments as well as a mass spectrometer to affirm its molecular mass. The F3 that yielded compound 1 had palpable antibacterial activities against Psp and Xap, with corresponding Minimum Inhibitory Concentration (MIC) values of 2.50 mg/ml (7.00 ± 0.00 mm) and 1.25 mg/ml (7.67 ± 0.33 mm) against the tests organisms respectively. These slight MIC values are chiefly attributed to the presence of active secondary metabolites in the fungal extracts that act against the test pathogens. This has therefore confirmed that fungal endophytes and their extractives have desirable antibacterial activities hence can be used in the formulation of agrochemicals or used as bio-control agents in crop protection especially in common beans (Phaseolus vulgaris L). Key words: Endophytes, Diaporthe sp, bean bacterial pathogens.

Three new bufadienolides, namely, paulliniogenin A (1), paulliniogenin B (2), and 16β-formyloxybersamagenin 1,3,5-orthoacetate (3), together with two known bufadienolides and six known phenolic substances, were isolated from the stem bark of Bersama abyssinica subsp. abyssinica and B. abyssinica subsp. paullinioides. The structures of the compounds were elucidated based on their NMR and HRMS data analyses. The relative configurations were defined by single-crystal X-ray crystallography and NOESY correlations. Cytotoxicity against the L929 and KB3.1 cancer cell lines of the isolated compounds was investigated using an MTT assay. Paulliniogenin A (1) and 16β-hydroxybersamagenin-1,3,5-orthoacetate (4) showed cytotoxicity against the KB3.1 cell line with IC50 values of 1.4 ± 0.77 and 1.6 ± 0.81 μM, respectively. Moreover, paulliniogenin A (1) and paulliniogenin B (2) demonstrated weak activity against Staphylococcus aureus.

Infectious diseases are major threat to public health; a problem that has been exacerbated by emergence of multi-drug resistant (MDR) strains. Finding alternative antimicrobial compounds from natural sources such as fungal endophytes and medicinal plants is crucial for addressing antimicrobial resistance. Thus, in this study search for endophytes with antibacterial activities from leaves of medicinal plant Leucas martinicensis was undertaken. Three fungal endophytes were isolated from fresh leaves and characterized using ribosomal Internal Transcribed Spacer (ITS) DNA. Antibacterial activities against five bacterial pathogens were determined using dual cultures and, disc diffusion assay for ethyl acetate extracts and pure compounds. Fungal endophytes isolated were LM-L(1), AD-L(1) and LM-S(6) belonging to genera Nigrospora, Diaporthe and Epicoccum, respectively. Axenic cultures and ethyl acetate extracts displayed antagonistic activity against Escherichia coli, Staphylococcus aureus, Proteus vulgaris, Klebsiella pneumoniae and Salmonella typhi unlike pure compounds. Irrespective of endophyte isolate, increasing the concentration of ethyl acetate fractions from 0.625 to 5.0 mg/ml during minimum inhibitory concentration (MIC) assay increased antibacterial activity; although 2 to 3 folds lower than chloramphenicol at 30 µg/disc. However, ethyl acetate fraction F3 at 5.0 mg/ml obtained from isolate LM-L(1) isolate belonging to genus Nigrospora produced activity that was not significantly (p≥0.05) different from chloramphenicol discs. Failure of pure compounds unlike ethyl acetate and axenic endophyte cultures suggests antibacterial activity observed was due to synergistic interactions of compounds. Nonetheless, the results demonstrate that fungal endophytes isolated from L. martinicensis possess antibacterial compounds which can be exploited further as lead compounds towards addressing antimicrobial drug resistance. Key words: Fungal endophytes, antimicrobial activity, drug resistance, Leucas martinicensis

Three previously undescribed compounds named heimiomycin A−C (1−3), featuring a unique scaffold with calamenene connected to a hydroxystyryl-pyranone moiety, along with the new calamenene derivatives 4 and 5 and phenanthridine derivative (6) were obtained from a culture of a Heimiomyces sp. This is the first report of the occurrence of calamenene-type terpenoids in fungi. Compound 3 exhibited antimicrobial activity against Gram-positive bacteria and Mucor hiemalis. Compounds 1 and 3 displayed moderate cytotoxicity against KB 3.1 and L929 cell lines, respectively.

Polygodial is a "hot" peppery-tasting sesquiterpenoid that was first described for its anti-feedant activity against African armyworms. Using the haploid deletion mutant library of Saccharomyces cerevisiae, a genome-wide mutant screen was performed to shed more light on polygodial's antifungal mechanism of action. We identified 66 deletion strains that were hypersensitive and 47 that were highly resistant to polygodial treatment. Among the hypersensitive strains, an enrichment was found for genes required for vacuolar acidification, amino acid biosynthesis, nucleosome mobilization, the transcription mediator complex, autophagy and vesicular trafficking, while the resistant strains were enriched for genes encoding cytoskeleton-binding proteins, ribosomal proteins, mitochondrial matrix proteins, components of the heme activator protein (HAP) complex, and known regulators of the target of rapamycin complex 1 (TORC1) signaling. WE confirm that polygodial triggers a dose-dependent vacuolar alkalinization and that it increases Ca2+ influx and inhibits glucose-induced Ca2+ signaling. Moreover, we provide evidence suggesting that TORC1 signaling and its protective agent ubiquitin play a central role in polygodial resistance, suggesting that they can be targeted by polygodial either directly or via altered Ca2+ homeostasis. ispartof: INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES vol:22 issue:11 ispartof: location:Switzerland status: published

Three new bufadienolides, namely, paulliniogenin A (

The Lablab bean (Lablab purpureus) has potential of being an outstanding resource for human food and animal feed in tropical agricultural systems. The bean is however grossly underutilized due to anti-nutritional factors, which may affect its nutritive value and organoleptic properties. In this study, twenty-four (24) lablab bean accessions were assayed for sensory flavor characteristics and volatile compounds to identify acceptable selections for adoption and incorporation into a rationalized breeding program. Sensory tests were carried out by a panel of 11 trained evaluators. Volatile compounds were extracted using hexane and separated using gas chromatography. Sensory tests showed significant differences for the bitter taste (p≤0.05), with accession 10706 showing the highest odour and bitter taste levels, while accession 13096 had the lowest. Two hundred and sixty two (262) volatile compounds were identified and grouped into 12 classes. The major compounds were esters (46), terpenes and terpenoids (59), hydrocarbons (57), and alcohols (28). The retention times of the volatile compounds revealed an overall 89% similarity of the lablab bean accessions. Accessions showing lower levels of bitter taste are recommended for inclusion in the participatory evaluation stage of the breeding process. Key words: Lablab purpureus, odour, flavour, taste, volatile compounds, underutilized crops.

Saponins are a major family of secondary metabolites that occur in a wide range of plant species. Bioassay - guided fractionation of extract of the leaves of Polyscias fulva led to the isolation of three known saponins named, 3-O-α-L-arabinopyranosyl-hederagenin (1), 3-O-[α-L-rhamnopyranosyl(1-2)-α-L-arabinopyranosyl]-hederagenin (2) and 3-O-[rhamnopyranosyl-(1→2)-xylopyranosyl]-Olean-12-en-28-O-[rhamnopyranosyl-(1→4)-glucopyranosyl-(1→6-glucopyranosyl] ester) (3). Leaves of the plant were collected from Kakamega rain forest in Kenya, dried under shade and ground into fine powder and extraction was done using methanol. The methanol extract was subjected to column chromatography and the fractions purified using preparative high performance liquid chromatography (HPLC). The bioactivity of the pure compounds was done using disc diffusion method. The three compounds exhibited moderate activities against Gram positive bacterium (Staphylococcus aureus ATCC25922) and Gram negative bacterium (Klebsiella pneumoniae ATCC13883). Compound 1 was found to be the most active against K. pneumoniae (8.00±1.00 mm) and S. aureus (10.00±1.73 mm) followed by compound 2 with inhibition zones of 7.66±0.57 and 7.33±0.57 mm against K. pneumoniae and S. aureus, respectively. Compound 3 was the least active against both K. pneumoniae (7.33±0.57 mm) and S. aureus (7.00±1.00 mm). The results obtained indicate that compounds 1, 2 and 3 exhibit potential as possible sources of antibacterial agents. Key words: Antibiotics, bacterial infections, antibiotic resistance, Polyscias fulva, saponins.

Microbial diseases remain to be a major global public health challenge. Their devastating effects have been exacerbated by the development of drug resistant strains. On the other hand, the biodiversity of tropical Basidiomycetes fungi is well recognized as an untapped source of potential bioactive compounds for the development of novel antimicrobials. Thus, in the current study, Basidiomycetes’ fruiting bodies were collected from Mt. Elgon National Park forest in Kenya. The spores were cultured on Yeast Malt Agar media (YMG), leading to the establishment of 12 distinct pure fungal cultures of Basidiomycete strains, which were characterized using ribosomal internal transcribed spacer (ITS) DNA. They generally belonged to genera; Inonotus, Fomitiporia, Ganoderma, Skeletocutis, Perenniporia, Favolaschia, Hexagonia, Polyporus, Antrodia and Echinochaete. Fungal mycelia were further fermented in YMG, Q6½ (cotton-seed) and ZM½ (sugar-malt) liquid media for secondary metabolites’ production. These were extracted using ethyl-acetate and subjected to antimicrobial assays against Bacillus subtilis, Escherichia coli, Mucor plumbeus and Candida albicans. Antimicrobial activity was exhibited in 9 out of the 12 strains cultured, where antibacterial activity was more pronounced than fungal antagonism. Mycelial crude extracts from strains identified as Skeletocutis nivea and Favolaschia calocera demonstrated the highest activities against bacteria (B. subtilis) and fungal pathogen (C. tenuis), respectively with minimum inhibitory concentration (MIC) values of 4.69 µg/ml and

Antibacterial activity of extracts of Zanthoxylum gilletii, Markhamia lutea and their fungal endophytes were evaluated against bacterial pathogens of common bean: Xanthomonus axonopodis pv. phaseoli and Pseudomonus syringae pv. phaseolicola. The leaves of both plants were dried under shade, ground to fine powder and extracted using methanol. The methanol extracts were fractionated sequentially using ethylacetate and hexane to produce various fractions. Endophytic fungi were isolated from fresh leaves and identified by ITS-rDNA sequence analysis. Antibacterial screening of the fungal endophytes was done by dual culture assay. The most active endophytic fungi were fermented on rice media and extracted using methanol. Pure compounds were analyzed by a combination of mass spectrometry and spectroscopic techniques which included 1D and 2D NMR. Antibacterial activity of all the extracts was determined by disc agar diffusion assay against the test organisms. Twenty-four (24) fungal endophytes were isolated which included: Fusarium, Chaetomium, Scopulariopsis and Trametes. Endophytic Fusarium solani was the most active against X. axonopodis pv. phaseoli (20.3 mm inhibition zone) and P. syringae pv. phaseolicola (18.6 mm inhibition zone). The plant extracts were active against X. axonopodis pv. phaseoli with an inhibition zone ranging between 8-12 mm except the methanol extract from Z. gilletii which did not show any activity. The endophytic extracts were active against both test organisms with a zone of inhibition ranging from 9.3-14 mm. Phenolic compounds present in Fusarium species may have contributed to the antibacterial activity of this strain against the test organisms. Key words: Common bean, medicinal plants, fungal endophytes, antibacterial activity, Xanthomonus axonopodis pv phaseoli, Pseudomonus syringae pv phaseolicola.

Infectious diseases remain a global health burden due to development of antibiotic resistance by pathogenic microorganisms. Antibiotic resistance has led to increased number of deaths among children and adults. This study sought to isolate and identify fungal endophytes from selected Kenyan medicinal plants and screen them and their extracts for bioactivity against selected test human pathogens. Fifty-five fungal endophytes were successfully isolated from fresh leaves of twenty-three medicinal plants from Kakamega forest. The DNA of fungal endophytes was extracted and molecular characterization was done through sequencing of the internal transcribed spacer region (ITS). The isolated fungal endophytes belonged to nine genera in the Ascomycota group, namely Fusarium, Colletotrichum, Trichothecium, Phomopsis, Pestalotiopsis, Cladosporium, Aspergillus, Phoma, and Chaetomium. Extracts from Aspergillus sp. demonstrated antimicrobial activity at low concentrations of 2.34 µg/ml against B. subtilis and 9.38 µg/ml against Candida tenius; while extracts from Colletotrichum sp. demonstrated antimicrobial activity at moderate concentration (37.5 µg/ml) against B. subtilis in the serial dilution assay. These results show that medicinal plants are a reservoir to a diversity of fungal endophytes that could be exploited as sources of natural products of pharmaceutical importance. Key words: Antibiotic resistance, antimicrobial, bioactive, fungal endophytes.

The need for effective compounds to combat antimicrobial resistance and biofilms which play important roles in human infections continues to pose a major health challenge. Seven previously undescribed acyclic diterpenes linked to isocitric acid by an ether linkage, microporenic acids A-G (1-7), were isolated from the cultures of a hitherto undescribed species of the genus Microporus (Polyporales, Basidiomycota) originating from Kenya's Kakamega forest. Microporenic acids D and E (4 and 5) showed antimicrobial activity against a panel of Gram positive bacteria and a yeast, Candida tenuis. Moreover, microporenic acids A and B (1 and 2) demonstrated dose-dependent inhibition of biofilm formation by Staphylococcus aureus. Compound 1 further showed significant activity against Candida albicans and Staphylococcus aureus preformed biofilms.

In continuation of a search for new antiprotozoal agents from plants of the family Asteraceae, Tarchonanthus camphoratus and Schkuhria pinnata have been investigated. By following the promising in vitro activity of the dichloromethane extracts from their aerial parts, bioassay-guided chromatographic isolation yielded two known sesquiterpene lactones (1 and 2) from T. camphoratus and 20 known compounds of this type from S. pinnata. From the latter, a new eudesmanolide, (1R*,5S*,6R*,7R*,8R*,10R*)-1-hydroxy-8-[5″-hydroxy-4'-(2″-hydroxyisovaleroyloxy)tigloyloxy]-3-oxoeudesma-11(13)-en-6,12-olide (3), and two new germacranolides, 3β-(2″-hydroxyisovaleroyloxy)-8β-(3-furoyloxy)costunolide (14) and 1(10)-epoxy-3β-hydroxy-8β-[5'-hydroxy-4'-(2″-hydroxyisovaleroyloxy)tigloyloxy]costunolide (16), were obtained. Additionally, the flavonoid pectolinarigenin (24) and 3-hydroxy-4,5-dimethoxybenzenepropanol (25) were also isolated from S. pinnata. The compounds were characterized by analysis of 1D and 2D NMR spectroscopic and HR/MS data. In vitro antitrypanosomal activity and cytotoxicity against mammalian cells (L6 cell line) were evaluated for all the compounds. Santhemoidin A (13) and 3β-(2″-hydroxyisovaleroyloxy)-8β-(3-furoyloxy)costunolide (14) were the most active compounds found in this study, with IC50 values of 0.10 and 0.13 μM against Trypanosoma brucei rhodesiense trypomastigotes and selectivity indices of 20.5 and 29.7, respectively.

Tarwish B, Ngeranwa JJN, Matasyoh JC. 2017. Larvicidal activity and phytochemical composition of crude extracts derived from Vernonia spp. against Anopheles gambiae. Bonorowo Wetlands 1: 108-116. This study aimed to elucidate the larvicidal activity of three species of Vernonia, i.e., Vernonia lasiopus, V. auriculifera and V. galamensis against the malaria vector Anopheles gambiae. Dried samples from leaves and roots of the three plants were sequentially extracted with hexane, chloroform, ethyl acetate, acetone, methanol, and water. Following rotor evaporation of the solvents, the extracts were subjected to phytochemical analysis and larvicidal assays against the third instar larvae of A. gambiae. The phytochemical screening revealed the presence of steroids, saponins, flavonoids, terpenoids, and cardiac glycosides in all extracts. Tannins were present in methanol and water extracts of all the three plants and acetone extract of V. lasiopus roots, V. auriculifera root, and V. galamensis leaf. Phlobatannins were absent in all extracts. Percent mortality for different concentration 125, 250, 500, 750 and 1000 ppm of the extracts was calculated and subsequently subjected to probit regression analysis to determine LC50 and LC90 values. The most active extract recorded was that of acetone root extract of V. galamensis with an LC50 of 22.85. Vernonia auriculifera and V. lasiopus recorded the highest activity in acetone root extract, and ethyl acetate root extract with an LC50 value of 37.7 and 205.9 respectively. One-Way ANOVA test was performed to compare the mean mortality of all tested groups. At all exposure hours except at 3 hours, the differences were found to be significant. The Tukey post hoc tests indicated that the mortality rate for V. galamensis was substantially different from the mortality rates of V. lasiopus and V. auriculifera after 24 hours. This study underlines V. lasiopus, V. auriculifera, and V. galamensis as an alternative source of new, cheap and readily available larvicides for control of the mosquito vector A. gambiae. Further study is required to determine what secondary metabolites in Vernonia extracts are responsible for the larvicidal activity.

HPLC profiling of the mycelial culture of a poroid basidomycete collected in Mount Elgon, Kenya, which probably represents a new species of the genus Laetiporus , led to isolation of two previously undescribed lanostane type triterpenes.We propose the trivial names laetiporins A ( 1 ) and B ( 2 ). In addition, five known ones: dehydrosulphurenic acid ( 3 ), sulphurenic acid ( 4 ), eburicoic acid ( 5 ), 15α-hydroxytrametenolic acid ( 6 ) and trametenolic acid ( 7 ) were also isolated. The laetiporins ( 1–2 ) exhibited significant cytotoxic effects against various human cancer cells. The known compounds ( 3–5 ) and ( 7 ) also showed moderate cytotoxic activity, but none of the compounds showed any significant antimicrobial activity.

During the course of searching for new anti-infective and other biologically active secondary metabolites from Kenyan basidiomycetes, 13 previously undescribed metabolites, (6 R,7 S,10 R)-7,10-epoxy-7,11-dimethyldodec-1-ene-6,11-diol (1) and 12 sesquiterpenes named elgonenes A-L (2-13), and the known compound P-coumaric acid (14) were isolated from a basidiomycete collected in Mount Elgon Natural Reserve. The producing organism represents a new species of the genus Sanghuangporus, which is one of the segregates of the important traditional Asian medicinal mushrooms that were formerly known as the " Inonotus linteus" complex. The structure elucidation of compounds 1-13, based on 2D NMR spectroscopy, high-resolution mass spectrometry, and other spectral methods, and their antibacterial, antifungal, and cytotoxic activities are reported.

Human African trypanosomiasis (HAT), also commonly known as sleeping sickness, is a neglected tropical disease affecting millions of people in poorly developed regions in sub-Saharan Africa. There is no satisfactory treatment for this infection. The investment necessary to bring new drugs to the market is a big deterrent to drug development, considering that the affected communities form a non-lucrative sector. However, natural products and many sesquiterpene lactones (STLs) in particular are very strong trypanocides. Research and applications of nano-drug delivery systems such as nanoparticles (NPs) have undergone unprecedented growth in the recent past. This is mainly due to the advantages offered by these systems, such as targeted delivery of the drug to the place of action (cell, parasite, etc), sustained release of the drug, increased bioavailability, reduced drug dosage, and reduction of undesired side effects, among others. In this study, the STLs α-santonin, arglabin, schkuhrin II, vernolepin, and eucannabinolide, all trypanocides, were loaded into polylactic acid (PLA) NPs through an emulsification-diffusion method. The NPs were stable, homogenous, and spherical in shape with a rounded knotty depression like a navel orange. The average particle sizes were 202.3, 220.3, 219.5, 216.9, and 226.4 nm for α-santonin, arglabin, schkuhrin II, vernolepin, and eucannabinolide, respectively. The NPs had encapsulation efficiencies of 94.6, 78.1, 76.8, 60.7, and 78.9% for α-santonin, arglabin, schkuhrin II, vernolepin, and eucannabinolide, respectively. The NPs loaded with arglabin, vernolepin, and eucannabinolide exhibited considerable antitrypanosomal activity against Trypanosoma brucei rhodesiense (Tbr) with free drug equivalent IC50 values of 3.67, 1.11 and 3.32 µM, respectively. None of the NP formulations displayed cytotoxicity towards mammalian cells (rat skeletal myoblast cell line L6). These results provide new insights into the possibility of incorporating STLs into nanoparticles, which may provide new options for their formulation in order to develop new drugs against HAT.

Fermentation of the fungal strain Skeletocutis sp. originating from Mount Elgon Natural Reserve in Kenya, followed by bioassay guided fractionation led to the isolation of 12 previously undescribed metabolites named skeletocutins A-L (1–5 and 7–13) together with the known tyromycin A (6). Their structures were assigned by NMR spectroscopy complemented by HR-ESIMS. Compounds 1–6 and 11–13 exhibited selective activities against Gram-positive bacteria, while compound 10 weakly inhibited the formation of biofilm of Staphylococcus aureus. The isolated metabolites were also evaluated for inhibition of L-leucine aminopeptidase, since tyromycin A had previously been reported to possess such activities but only showed weak effects. Furthermore, all compounds were tested for antiviral activity against Hepatitis C virus (HCV), and compound 6 moderately inhibited HCV infectivity with an IC50 of 6.6 μM.

In continuation of a previous quantitative structure-activity relationship (QSAR) study on the antitrypanosomal activity of 69 sesquiterpene lactones (STLs) towards Trypanosoma brucei rhodesiense (Tbr) [1], the causative agent of East African form of human African trypanosomiasis, a QSAR model for a much larger and more diverse set of almost twice as many (130) of such natural products was established in this study. The extended data set has been obtained through a variety of STLs isolated and tested for antitrypanosomal activity within our group and further enhanced by 12 compounds obtained from literature, which have been tested in the same laboratory under identical conditions. Detailed QSAR analyses using various complementary approaches: (1) “Classical” descriptor-based QSAR using a genetic algorithm to select the most relevant variables, i.e. the same approach as in our previous study [1], (2) indicator variables deduced from pharmacophore features obtained from a 3D alignment of the most active molecules as applied in [2] and (3) hologram QSAR (HQSAR) based on molecular fingerprints of fragments extracted from the 2D molecular structure as used, e.g., in [3], have yielded models with good internal and external predictive ability. For a set of compounds as chemically diverse as the one under study, the models exhibited good coefficients of determination (R2) ranging from 0.71 to 0.85, as well as internal (leave-one-out Q2 values ranging from 0.62 to 0.72) and external validation coefficients (P2 values ranging from 0.54 to 0.73). The contributions of the various tested descriptors to the generated models are in good agreement with the results of previous QSAR studies and corroborate the fact that the antitrypanosomal activity of STLs is very much dependent on the presence and relative position of conjugated carbonyl groups within the molecular structure, but influenced by their hydrophilic/hydrophobic property and molecular shape References Schmidt, T. J. et al. Antimicrob. Agents Chemother. 2014, 58 (1), 325–332. Schomburg, C. et al. Eur. J. Med. Chem. 2013, 63, 313–320. Trossini, G. H. G. et al. Molecules 2014, 19 (7), 10546–10562.

Three complementary quantitative structure–activity relationship (QSAR) methodologies, namely, regression modeling based on (i) “classical” molecular descriptors, (ii) 3D pharmacophore features, and (iii) 2D molecular holograms (HQSAR) were employed on the antitrypanosomal activity of sesquiterpene lactones (STLs) toward Trypanosoma brucei rhodesiense (Tbr), the causative agent of the East African form of human African trypanosomiasis. In this study, an extension of a previous QSAR study on 69 STLs, models for a much larger and more diverse set of such natural products, now comprising 130 STLs of various structural subclasses, were established. The extended data set comprises a variety of STLs isolated and tested for antitrypanosomal activity within our group and is furthermore enhanced by 12 compounds obtained from literature, which have been tested in the same laboratory under identical conditions. Detailed QSAR analyses yielded models with comparable and good internal and external predictive ability. For a set of compounds as chemically diverse as the one under study, the models exhibited good coefficients of determination (R2) ranging from 0.71 to 0.85, as well as internal (leave-one-out Q2 values ranging from 0.62 to 0.72) and external validation coefficients (P2 values ranging from 0.54 to 0.73). The contributions of the various tested descriptors to the generated models are in good agreement with the results of previous QSAR studies and corroborate the fact that the antitrypanosomal activity of STLs is very much dependent on the presence and relative position of reactive enone groups within the molecular structure but is influenced by their hydrophilic/hydrophobic properties and molecular shape.

Phytopathogens are known to be the leading cause of important plant diseases which result in significant losses in agricultural crops. The need to maintain the level of yield both quantitatively and qualitatively is vital in order to curb the losses. So far there has been a positive advance recognized in research to the use of tropical fungi as biocontrol agents. The objective of this study was to screen for antagonistic tropical fungi against selected phytopathogens of maize ( Zea mays L.) and beans ( Phaseolus vulgaris L.) namely Fusarium graminearum, Fusarium moniliforme, Pythium ultimum, and Colletotrichum lindemuthianum in vitro. A total of 87 tropical fungi isolates were collected from Kakamega tropical rainforest, Kenya. Dual culture experiment was carried out to screen the tropical fungi against the selected phytopathogens. The bioassay was performed in a completely randomised design in triplicate and the inhibition zones recorded after every week for three weeks. Differential biocontrol ability among nine tropical fungi was noticed against F. moniliforme with the percentage inhibition increasing over time. Fusarium solani was the most active antagonist with an inhibition of 64% while Phaeomarasmius sp. had the lowest activity of 19.1% against F. moniliforme . Epicoccum sp. inhibited the mycelial growth of P. ultimum by 38% and also inhibited C . lindemuthianum by 58%. None of the fungal antagonists inhibited the mycelial growth of F . graminearum . The outcome of this study indicates that tropical fungi can be used as biocontrol agents and can be further explored and developed into effective fungicides for management of phytopathogens.

Bioassay-guided fractionation of the mycelial extract of a basidiomycete culture collected in Kenya led to the isolation of two new cyathane diterpenoids named laxitextines A (1) and B (2). The producer strain was characterized by detailed taxonomic studies based on rDNA using the 5.8S gene region, the internal transcribed spacer 2 (ITS2), and part of the large subunit that identified the fungus as Laxitextum incrustatum. The structures of 1 and 2 were elucidated by NMR spectroscopic and mass spectrometric analyses. Both compounds exhibited moderate activities against Gram-positive bacteria Bacillus subtilis (DSM 10), Staphylococcus aureus (DSM 346), and methicillin-resistant Staph. aureus (DSM 1182). The two compounds also showed variable antiproliferative activities against mouse fibroblast (L929) and selected human cell lines (breast cancer MCF-7, epidermoid carcinoma A431, and umbilical vein endothelial HUVEC). The IC50 values with respect to the MCF-7 cell line for compounds 1 and 2 were 2.3 and 2.0 μM, respectively.

Aim: In a bid to explore for grain bio-preservatives, essential oils extracted from Cymbopogon citratus, Rosmarinus officinalis, Monanthataxis littoralis and Aframomum angustifolium, that were earlier established to have anti-mold activity, were evaluated for their biosafety by determining the oral LD50. Methods: The essential oils were extracted by hydro-distillation from aromatic plants collected from Kakamega and Mabira forests in Kenya and Uganda, respectively. Acute oral toxicity was established using mice by determining the LD50; after which sub-acute toxicity studies were performed. The animals were observed for behavioural changes; and the gross and Original Research Article Nakavuma et al.; EJMP, 14(2): 1-14, 2016; Article no.EJMP.25185 2 histopathological effects, if any, on the intestinal mucosa, spleen, lungs, liver, kidney and heart were noted. Results: The oral LD50 for Cymbopogon citratus, Rosmarinus officinalis, Monanthataxis littoralis and Aframomum angustifolium essential oils were established as 7,046.90; 4,723.33; 13,335.82; and 17,539.82 (mg/kg body weight), respectively. In all cases, increased breathing rates were observed, however Rosemary also caused lethargy and convulsions. Grossly, no changes were seen in the liver, kidney, lungs, heart and spleen from both the control and the treated mice except for Monanthataxis littoralis where the lungs and liver seemed changed; and the urinary bladder distended. However, the latter effects were noted at higher doses than the established oral LD50. Histopathologically, thickened intestinal mucosa lining; tubular degeneration and proteinuria in the kidneys; vascular congestion, focal necrosis and hydropic degeneration of hepatocytes in the liver, were encountered. Conclusion: Basing on the oral LD50 in mice, all oils were safe and can be explored further as antimold grain preservatives. However, Rosmarinus officinalis was marginally safe as per the OECD guidelines. The histopathological effects of Monanthataxis littoralis essential oil need to be investigated further.

ETHNOPHARMACOLOGICAL RELEVANCE: Warburgia ugandensis Sprague subspecies ugandensis is a plant widely distributed in Eastern, Central and Southern Africa. In humans, it is used to treat respiratory infections, tooth aches, malaria, skin infections, venereal diseases, diarrhea, fevers and aches. AIM OF THE STUDY: This study aims to identify the bioactive compounds against clinically important biofilm-forming strains of Candida and staphylococci that are responsible for tissue and implanted device-related infections. METHODS: Using a bioassay-guided fractionation approach, hexane -, ethanol -, acetone - and water extracts from the leaves of W. ugandensis, their subsequent fractions and isolated compounds were tested against both developing and preformed 24 h-biofilms of Candida albicans SC5314, Candida glabrata BG2, Candida glabrata ATCC 2001, Staphylococcus epidermidis 1457 and Staphylococcus aureus USA 300 using microtiter susceptibility tests. Planktonic cells were also tested in parallel for comparison purposes. Confocal scanning laser microscopy was also used to visualize effects of isolated compounds on biofilm formation. RESULTS: Warburganal, polygodial and alpha-linolenic acid (ALA) were the major bioactive compounds isolated from the acetone extract of W. ugandensis. For both warburganal and polygodial, the biofilm inhibitory concentration that inhibits 50% of C. albicans developing biofilms (BIC50) was 4.5 ± 1 and 10.8 ± 5 μg/mL respectively. Against S. aureus developing biofilms, this value was 37.9 ± 8 μg/mL and 25 μg/mL with warburganal and ALA respectively. Eradication of preformed 24 h biofilms was also observed. Interestingly, synergy between the sesquiterpenoids and azoles against developing C. albicans biofilms resulted in an approximately ten-fold decrease of the effective concentration required to completely inhibit growth of the biofilms by individual compounds. The hydroxyl group in position C-9 in warburganal was identified as essential for activity against staphylococcal biofilms. We also identified additional promising bioactive sesquiterpenoids; drimenol and drimendiol from the structure-activity relationship (SAR) studies. CONCLUSIONS: ALA and four sesquiterpenoids: polygodial, warburganal, drimenol and drimendiol, have shown biofilm-inhibitory activity that has not been reported before and is worth following up. These compounds are potential drug candidates to manage biofilm-based infections, possibly in combination with azoles. ispartof: JOURNAL OF ETHNOPHARMACOLOGY vol:248 ispartof: location:Ireland status: published

Bioassay guided fractionation of extracts derived from submerged cultures of a Sanghuangporus sp. (i.e., the genus that was until recently referred to as the “Inonotus linteus complex” of medicinal mushrooms) originating from Kenya led to the isolation of a new spiro [furan-2,1’-indine]-3-one derivative, for which we propose the trivial name phelligridin L (1) together with the known compounds 3,14′-bihispidinyl (2), hispidin (3), ionylideneacetic acid (4), 1S-(2E)-5-[(1R)-2,2-dimethyl-6-methylidenecyclohexyl]-3-methylpent-2-enoic acid (5), phellidine E (6) and phellidine D (7). Compounds 1–3, showed moderate nematicidal activity against Caenorhabditis elegans with LD50 of 12.5 μg/m. The nematicidal activity of 3, 14′-bihispidinyl and hispidin (1, 2) has not been reported before. Furthermore, compounds 1–5 demonstrated moderate antimicrobial activity against various test organisms.

In the endeavor to obtain new antitrypanosomal agents, particularly sesquiterpene lactones, from Kenyan plants of the family Asteraceae, Vernonia cinerascens Sch. Bip. was investigated. Bioactivity-guided fractionation and isolation in conjunction with LC/MS-based dereplication has led to the identification of vernodalol (1) and isolation of vernodalin (2), 11β,13-dihydrovernodalin (3), 11β,13-dihydrovernolide (4), vernolide (5), 11β,13-dihydrohydroxyvernolide (6), hydroxyvernolide (7), and a new germacrolide type sesquiterpene lactone vernocinerascolide (8) from the dichloromethane extract of V. cinerascens leaves. Compounds 3-8 were characterized by extensive analysis of their 1D and 2D NMR spectroscopic and HR/MS spectrometric data. All the compounds were evaluated for their in vitro biological activity against bloodstream forms of Trypanosoma brucei rhodesiense and for cytotoxicity against the mammalian cell line L6. Vernodalin (2) was the most active compound with an IC50 value of 0.16 µM and a selectivity index of 35. Its closely related congener 11β,13-dihydrovernodalin (3) registered an IC50 value of 1.1 µM and a selectivity index of 4.2.

An endophyte is a fungus or bacterium that lives within a plant in a symbiotic relationship. Extensive colonization of the plant tissue by endophytes creates a barrier effect, where they outcompete and prevent pathogenic organisms from taking hold. This happens by producing secondary metabolites that inhibit the growth of the competitors or pathogens. In this way they play a very important role in the plant defence mechanisms. The metabolites produced by these endophytes fall within a wide range of classes of compounds that include peptides which are the focus of this review. Peptides are increasingly being selected for drug development because they are specific for their targets and have a higher degree of interactions. There have been quite a number of endophytic peptides reported in the recent past indicating that endophytes can be used for the production of peptide based drugs. Molecular screening for NRPS, which shows peptide producing capability, has also shown that endophytes are potential producers of peptides. The presence of NRPS also offers the possibility of genetic modifications which may generate peptides with high pharmacological activities. This review, therefore, aims to show the current status of peptides isolated from endophytic bacteria and fungi in the recent decade. Endophytes as potential sources of peptides according to NRPS studies will also be discussed.

Eight previously undescribed compounds were isolated and characterised from the supernatant and mycelium of a culture of the basidiomycete Favolaschia calocera originating from Kakamega equatorial rainforest in Kenya. These were: 9- oxostrobilurins A, G, K and I and the four monochlorinated calocerins A, B, C and D. The calocerins extend our knowledge of halogenated compounds obtained from natural sources. Four further known compounds were also identified: strobilurin G, favolon, pterulinic acid and 2,3 -dihydro-1-benzoxepin derivative. The four oxostrobilurins exhibited prominent antifungal and cytotoxic activities while the four calocerins only showed cytotoxic activity.

Two new N-methylated cyclopeptides, persipeptide A (1) and B (2), have been isolated from Streptomyces sp. UTMC1154. Their structures were established using 1D and 2D NMR experiments. 2D TOCSY experiments were applied to identify the amino acid residues, while HMBC correlations were used to determine their sequence. According to Marfey’s method, all amino acids had the l -configuration. The two cyclic peptides had the same ring size and amino acid composition, but differed in their sequence; they did not show activity against the tested bacteria, fungi and algae. Molecular identification experiments placed the strain in the genus Streptomyces closely related to Streptomyces coerulescens DSM40146T (99.45%) and Streptomyces varsoviensis DSM40346T (99.25%).

Four alkaloids, 10-O-demethyl-17-O-methylisoarnottianamide 1, 6-acetonyl-N-methyl-dihydrodecarine 2, nitidine 3, and chelerythrine 4 were isolated from the plant Zanthoxylum lemairei (Rutaceae) and evaluated for mosquito larvicidal activity against the malaria vector Anopheles gambiae. The mortalities of the larvae were determined after 24 h. The results of the larvicidal tests demonstrated that compounds 1 and 2 were the most potent with mortality rates of 96.7% and 98.3% at a concentration of 250 mg/L, respectively. Compound 3 was less potent with a mortality of 28.3% at the same concentration. The percent mortality of 100% was observed at a concentration of 500 mg/L. The least potent of the four alkaloids was compound 4, which achieved 100% mortality at 1000 mg/L. These findings could be useful in the research for newer more selective, biodegradable and natural larvicidal compounds or can be used as lead compounds for the development of larvicides.

In a screening for natural products with mosquito larvicidal activities, the endophytic fungus Podospora sp. isolated from the plant Laggera alata (Asteraceae) was conspicuous. Two xanthones, sterigmatocystin (1) and secosterigmatocystin (2), and an anthraquinone derivative (3) 13-hydroxyversicolorin B were isolated after fermentation on M2 medium. These compounds were characterised using spectroscopic and X-ray analysis and examined against third instar larvae of Anopheles gambiae. The results demonstrated that compound 1 was the most potent one with LC50 and LC90 values of 13.3 and 73.5 ppm, respectively. Over 95% mortality was observed at a concentration 100 ppm after 24 h. These results compared farvourably with the commercial larvicide pylarvex® that showed 100% mortality at the same concentration. Compound 3 was less potent and had an LC50 of 294.5 ppm and over 95% mortality was achieved at a concentration of 1,000 ppm. Secosterigmatocystin (2) revealed relatively weak activity and therefore LC values were not determined. peerReviewed