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During the course of our ongoing studies on the secondary metabolism of cultures of Basidiomycota, a new meroterpenoid named 10, 15-dihydroxydihydromelleolide (1) was isolated along with the known armillaridin (2) and arnamiol (3) from cultures of the rare saprotrophic species, Desarmillaria ectypa. These are the first secondary metabolites that were ever isolated from the latter species. A concurrently studied strain of the common pathogenic A. mellea yielded other melleolides, with 5'-O-methylmelledonal (4), melledonal C (5), 10 α-hydroxydihydromelleolide (6) and melledonal (7). The chemical structures were elucidated using 1D and 2D NMR spectroscopy and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). All compounds were studied for their antimicrobial and cytotoxic effects against a panel of microbes and mammalian cell lines, and the results are also reported., (© 2024 The Authors. Chemistry & Biodiversity published by Wiley-VHCA AG.)

Three novel derivatives of microporenic acid, microporenic acids H-J, were identified from submerged cultures of a Lentinus species obtained from a basidiome collected during a field trip in the tropical rainforest in Western Kenya. Their structures were elucidated via HR-ESIMS spectra and 1D/2D NMR spectroscopic analyses, as well as by comparison with known derivatives. Applying biofilm assays based on crystal violet staining and confocal microscopy, two of these compounds, microporenic acids H and I, demonstrated the ability to inhibit biofilm formation of the opportunistic pathogen Staphylococcus aureus. Thereby, they were effective in a concentration range that did not affect planktonic growth. Additionally, microporenic acid I enhanced the anti-biofilm activity of the antibiotics vancomycin and gentamicin when used in combination. This opens up possibilities for the use of these compounds in combination therapy to prevent the formation of S. aureus biofilms., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

The methanol stem bark extract of A. boonei and methanol seed extract of P. nitida , were subjected to purification using chromatographic techniques. A. boonei yielded loganic acid ( 1 ), sweroside ( 2 ) and secoxyloganin ( 3 ), while P. nitida afforded (1) , akuammidine ( 4 ), akuammicine ( 5 ) and alstonine ( 6 ). The structures of the compounds were elucidated based on their nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS) profiles and comparison with literature data. The antibacterial activities of the compounds were evaluated using the disc diffusion assay with chloramphenicol as the positive control. Alstonine ( 6 ) demonstrated weak activity against Pseudomonas aeruginosa and Streptococcus agalactiae with zones of inhibition of 9.3 ± 0.6 and 10.0 ± 0.0 mm, respectively. This is the first report of sweroside ( 2 ) and secoxyloganin ( 3 ) in A. boonei .

Diabetes remains an important disease worldwide with about 500 million patients globally. In tropical Africa, Morus mesozygia is traditionally used in the treatment of diabetes. Biological and phytochemical investigation of the root bark extracts of the plant led to the isolation of a new prenylated arylbenzofuran named 7-(3-hydroxy-3-methylbutyl)moracin M ( 1 ) and two congeners, moracins P ( 2 ) and M ( 3 ). When compared to acarbose (IC 50 = 486 µM), all the isolated compounds are better inhibitors of α-glucosidase with in vitro IC 50 values of 16.9, 16.6, and 40.9 µM, respectively. However, they were not active against α-amylase. The compounds also demonstrated moderate inhibition of dipeptidyl peptidase-4 (DPP4). Based on in silico docking studies, all isolates ( 1 , 2 , and 3 ) exhibit binding affinities of -8.7, -9.5, and -8.5 kcal/mol, respectively against α-glucosidase enzyme (PDB: 3AJ7). They are stabilized within the α-glucosidase active site through hydrogen bonds, pi interactions, and hydrophobic interactions. This study provides scientific support for the traditional use of Morus mesozygia in the treatment of diabetes as well as adding to the repository of α-glucosidase inhibitory agents., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Olufolabo, Lüersen, Oguntimehin, Nchiozem-Ngnitedem, Agbebi, Faloye, Nyamboki, Rimbach, Matasyoh, Schmidt and Moody.)

From the leaves and stem bark of the Kenyan medicinal plant Calpurnia aurea subsp. aurea, four previously undescribed quinolizidine alkaloids namely, 2β-methoxy-13α-O-(2'-pyrrolylcarbonyl) virgiline, 2α-methoxy-13β-O-(2'-pyrrolylcarbonyl) virgiline, 3α-O-angelate-2β-hydroxy-13α-O-(2'-pyrrolylcarbonyl) virgiline, 2,3-dehydro-virgiline were isolated together with four known ones. Structural elucidation of the compounds was based on 1D and 2D NMR spectroscopy and mass spectrometry. Their relative configurations were determined by NOESY correlations and literature. The quinolizidine alkaloids were tested against Trichophyton rubrum, Trichophyton interdigitale, Trichophyton benhamiae, Microsporum canis and Nannizzia gypsea, common causative agents of most of the tinea infections in human. All the isolated quinolizidine alkaloids exhibited antidermatophytic activity with MIC ranging from 37.5 μg/ml to 300 μg/ml., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests. Josphat Matasyoh reports financial support was provided by Alexander von Humboldt Foundation. Josphat Matasyoh reports financial support was provided by German Academic Exchange Service. Josphat Matasyoh reports financial support was provided by Federal Ministry of Education and Research Berlin Office. Josphat Matasyoh reports financial support was provided by H2020 MSCA-RISE-2020Research and Innovation Staff Exchange., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Abundisporin A ( 1 ), together with seven previously undescribed drimane sesquiterpenes named abundisporins B-H ( 2 - 8 ), were isolated from a polypore, Abundisporus violaceus MUCL 56355 (Polyporaceae), collected in Kenya. Chemical structures of the isolated compounds were elucidated based on exhaustive 1D and 2D NMR spectroscopic measurements and supported by HRESIMS data. The absolute configurations of the isolated compounds were determined by using Mosher's method for 1 - 4 and TDDFT-ECD calculations for 4 and 5 - 8 . None of the isolated compounds exhibited significant activities in either antimicrobial or cytotoxicity assays. Notably, all of the tested compounds demonstrated neurotrophic effects, with 1 and 6 significantly increasing outgrowth of neurites when treated with 5 ng/mL NGF.

Four previously undescribed drimane sesquiterpenoids were isolated from submerged cultures of the wood-inhabiting basidiomycete Dentipellis fragilis along with two compounds that were previously reported as synthetic or biotransformation compounds but not as natural products. The constitution and relative configuration of these compounds was determined based on high-resolution electrospray ionization mass spectrometry as well as by 1D and 2D nuclear magnetic resonance spectroscopy. The absolute configurations were established based on exemplary calculation of circular dichroism spectra and comparison with measured data as well as on biogenetic considerations. The biological activities of the isolated compounds were assessed in antimicrobial, cytotoxicity and neurotrophic assays. 10-Methoxycarbonyl-10-norisodrimenin (3) exhibited weak activity against the Gram-positive bacterium Staphylococcus aureus and the zygomycete Mucor hiemalis with minimal inhibitory concentrations of 66.7 μg mL -1 . In addition, compound 3 showed weak inhibition of the mammalian cell line KB3.1 (human endocervical adenocarcinoma) with a half maximal inhibitory concentration of 21.2 μM. The neurotrophic activities of 15-hydroxyisodrimenin (1) and 10-carboxy-10-norisodrimenin (5) were assed in neurite outgrowth and real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) assays. When supplemented with 5 ng mL -1 nerve growth factor (NGF), the drimanes 1 and 5 induced neurite outgrowth in PC-12 (rat pheochromocytoma) cells compared to cells solely treated with NGF. As evaluated by RT-qPCR, compounds 1 and 5 also increased NGF and brain-derived neurotrophic factor expression levels in 1321N1 astrocytoma cells. Interestingly, the current study only represents the second report on neurotrophic activities of this widespread class of terpenoids. The only other available study deals with Cyathus africanus , another basidiomycete that can produce drimanes and cyathanes, but is only distantly related to Dentipellis and the Hericiaceae., Competing Interests: The authors have no relevant financial or non-financial interests to disclose., (This journal is © The Royal Society of Chemistry.)

Chemical exploration of solid-state cultures of the polypore Fomitopsis carnea afforded two new C31 lanostane-type triterpenoid glycosides, forpiniosides B ( 1 ) and C ( 2 ) together with two known derivatives, namely 3-epipachymic acid ( 3 ) and (3α,25 S )-3- O -malonyl-23-oxolanost-8,24(31)-dien-26-oic acid ( 4 ). The structures of the isolated compounds were established based on HRESIMS and extensive 1D and 2D NMR experiments. All the isolated compounds were assessed for their antimicrobial and cytotoxic activities. Among the tested compounds, forpinioside B ( 1 ) exhibited significant antimicrobial activity against Staphylococcus aureus and Bacillus subtilis at MIC values comparable to gentamycin and oxytetracycline (positive controls), respectively., (Copyright © 2023, Sum et al.)

Neurodegenerative diseases are currently posing huge social, economic, and healthcare burdens among the aged populations worldwide with few and only palliative treatment alternatives available. Natural products continue to be a source of a vast array of potent neurotrophic molecules that could be considered as drug design starting points. The present study reports eight new isoindolinone and benzofuranone derivatives, for which we propose the trivial names, hericioic acids A-G ( 1 - 7 ) and hericiofuranoic acid ( 8 ), which were isolated from a solid culture (using rice as substrate) of the rare European edible mushroom Hericium flagellum . The chemical structures of these compounds were determined based on extensive 1D and 2D NMR spectroscopy along with HRESIMS analyses. The isolated compounds were assessed for their neurotrophic activity in rat pheochromocytoma cells (PC-12) to promote neurite outgrowth on 5 ng NGF supplementation; all the compounds increased neurite outgrowths, with compounds 3 , 4, and 8 exhibiting the strongest effects.

With heimionones A-E ( 1 - 5 ), five new terpenoids were isolated from submerged cultures of Heimiomyces sp. in addition to the previously described compounds hispidin, hypholomin B, and heimiomycins A and B. Planar structures of the metabolites were elucidated by 1D and 2D NMR in addition to HRESIMS data. While ROESY data assigned relative configurations, absolute configurations were determined by the synthesis of MTPA esters of 1 , 3 , and 5 . The [6.3.0] undecane core structure of compounds 3 - 5 is of the asteriscane-type, however, the scaffold of 1 and 2 with their bicyclo [5.3.0] decane core and germinal methyl substitution is, to our knowledge, unprecedented. Together with several new compounds that were previously isolated from solid cultures of this strain, Heimiomyces sp. showed an exceptionally high chemical diversity of its secondary metabolite profile.

New meroterpenoids bis-heimiomycins A-D ( 1 - 4 ) and heimiomycins D and E ( 5 and 6 ) were isolated from solid rice cultures of Heimiomyces sp., while new calamene-type sesquiterpenoids heimiocalamene A ( 7 ) and B ( 8 ) were isolated from shake cultures, respectively. Structures of the metabolites were elucidated by 1D and 2D NMR in addition to HRESIMS data. While relative configurations were assigned by ROESY data, absolute configurations were derived from the structurally related, previously described calamenes, which we herein name heimiocalamenes C-E ( 9 - 11 ). A plausible biosynthetic pathway was proposed for 1 - 6 , with a radical reaction connecting their central para -benzoquinone building block to calamene-sesquiterpenoids. Based on the assumption of a common biosynthesis, we reviewed the structure of the known nitrogen-containing derivative 11 , calling the validity of the originally proposed structure into question. Subsequently, the structure of 11 was revised by analysis of HMBC and ROESY NMR data. Only heimiomycin D ( 5 ) displayed cytotoxic effects against cell line KB3.1.

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.

Five new drimane-type sesquiterpenoids were isolated from cultures of the tropical basidiomycetes, Perenniporia centrali-africana (originating from Kenya) and Cerrena sp. nov. (originating from Thailand). A new pereniporin A derivative ( 1 ), a new drimane-type sesquiterpene lactam ( 2 ), and the new 6,7-Dehydro-isodrimenediol ( 3 ) were isolated from P. centrali-africana. In parallel, the two new drimane-type sesquiterpene lactams 5 and 6 were isolated together with known isodrimenediol ( 4 ) from Cerrena sp. This is the first report of drimane-type sesquiterpene lactams from basidiomycetes. The structures were elucidated based on 1D and 2D nuclear magnetic resonance (NMR) spectroscopic data, in combination with high-resolution electrospray mass spectrometric (HR-ESIMS) data. The compounds were devoid of significant antimicrobial and cytotoxic activities.

In our continued search for biologically active metabolites from cultures of rare Basidiomycota species, we found eight previously undescribed cyathane-xylosides from submerged cultures of Dentipellis fragilis , which were named dentifragilins A-H. In addition, the known cyathane derivatives striatal D and laxitextine A were isolated. All compounds were characterized by high-resolution electrospray ionization mass spectrometry (HR-ESIMS) as well as by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. Several of the compounds exhibited significant activities in standardized cell-based assays for the determination of antimicrobial and cytotoxic effects. The discovery of cyathanes in the genus Dentipellis has chemotaxonomic implications, as this class of diterpenoids has already been shown to be characteristic for mycelial cultures of the related genera Hericium and Laxitextum , which are classified as Dentipellis in the family Hericiaceae.

From the leaves of Kenyan medicinal plant Bersama abyssinica Subspecies abyssinica, four previously undescribed compounds namely, three bufadienolides, 10β-formylpaulliniogenin B, 10β-formylpaulliniogenin A and 1β-acetoxy-3β,5β-dihydroxy-15-methoxy-16,19-dioxobufa-14(15),20,22-trienolide, and a phenolic compound 2,6,4'-trihydroxybenzophenone-4-O-(6‴-cinnamoyl)-β-D-glucoside were isolated together with four known compounds. The structural elucidation of the compounds was based on 1D and 2D NMR spectroscopy and HRMS data analyses. The relative configurations were defined by NOESY correlations. Cytotoxic activities on L929 and KB3.1 cell lines of the isolated compounds were investigated using MTT assay. The 1β-acetoxy-3β,5β-dihydroxy-15-methoxy-16,19-dioxobufa-14(15),20,22-trienolide showed significant cytotoxic activity against KB3.1 cell lines with IC 50 of 3.9 ± 0.99 μM., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A mycelial culture of the African basidiomycete Echinochaete cf. brachypora was studied for biologically active secondary metabolites, and four compounds were isolated from its crude extract derived from shake flask fermentations, using preparative high-performance liquid chromatography (HPLC). The pure metabolites were identified using extensive nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry (HR-MS). Aside from the new metabolites 1-methoxyneomarinone ( 1 ) and (E)-3-methyl-5-(-12,13,14-trimethylcyclohex-10-en-6-yl)pent-2-enoic acid ( 4 ), the known metabolites neomarinone ( 2 ) and fumaquinone ( 4 ) were obtained. Such compounds had previously only been reported from Actinobacteria but were never isolated from the cultures of a fungus. This observation prompted us to evaluate whether the above metabolites may actually have been produced by an endosymbiontic bacterium that is associated with the basidiomycete. We have indeed been able to characterize bacterial 16S rDNA in the fungal mycelia, and the production of the metabolites stopped when the fungus was sub-cultured on a medium containing antibacterial antibiotics. Therefore, we have found strong evidence that compounds 1 - 4 are not of fungal origin. However, the endofungal bacterium was shown to belong to the genus Ralstonia , which has never been reported to produce similar metabolites to 1 - 4 . Moreover, we failed to obtain the bacterial strain in pure culture to provide final proof for its identity. In any case, the current report is the first to document that polyporoid Basidiomycota are associated with endosymbionts and constitutes the first report on secondary metabolites from the genus Echinochaete .

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 IC 50 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 .

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.

During the course of screening for new metabolites from basidiomycetes, we isolated and characterized five previously undescribed secondary metabolites, skeletocutins M-Q ( 1 - 5 ), along with the known metabolite tyromycin A ( 6 ) from the fruiting bodies of the polypore Skeletocutis sp. The new compounds did not exhibit any antimicrobial, cytotoxic, or nematicidal activities. However, compound 3 moderately inhibited the biofilm formation of Staphylococcus aureus ( S. aureus ), while compounds 3 and 4 performed moderately in the ʟ-leucine-7-amido-4-methylcoumarin (ʟ-Leu-AMC) inhibition assay. These compounds represent the first secondary metabolites reported to occur in the fruiting bodies by Skeletocutis . Interestingly, tyromycin A ( 6 ) was found to be the only common metabolite in fruiting bodies and mycelial cultures of the fungus, and none of the recently reported skeletocutins from the culture of the same strain were detected in the basidiomes., (Copyright © 2019, Cheng et al.; licensee Beilstein-Institut.)

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 IC 50 of 6.6 μM.

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 IC 50 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.

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.

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 Q 2 values ranging from 0.62 to 0.72) and external validation coefficients ( P ² 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., Competing Interests: The authors declare no conflict of interest.

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.

A mycelial culture of the Kenyan basidiomycete Fomitiporia aethiopica was fermented on rice and the cultures were extracted with methanol. Subsequent HPLC profiling and preparative chromatography of its crude extract led to the isolation of five previously undescribed pregnenolone type triterpenes 1 - 5 , for which we propose the trivial name aethiopinolones A-E. The chemical structures of the aethiopinolones were determined by extensive 1D- and 2D-NMR, and HRMS data analysis. The compounds exhibited moderate cytotoxic effects against various human cancer cell lines, but they were found devoid of significant nematicidal and antimicrobial activities., Competing Interests: The authors declare no conflict of interest.

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 IC 50 value of 0.16 µM and a selectivity index of 35. Its closely related congener 11β,13-dihydrovernodalin ( 3 ) registered an IC 50 value of 1.1 µM and a selectivity index of 4.2., Competing Interests: The authors declare no conflict of interest.

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 IC 50 values of 0.10 and 0.13 μM against Trypanosoma brucei rhodesiense trypomastigotes and selectivity indices of 20.5 and 29.7, respectively.

Sleeping sickness or human African trypanosomiasis (HAT) is a neglected tropical disease (NTD) threatening millions of peoples' lives with thousands infected. The disease is endemic in poorly developed regions of sub-Saharan Africa and is caused by the kinetoplastid "protozoan" parasite Trypanosoma brucei . The parasites are transmitted to humans through bites of infected tsetse flies of the genus Glossina . The few available drugs for treatment of this disease are highly toxic, difficult to administer, costly and unavailable to poor rural communities bearing the major burden of this infection. Therefore, the search for new efficacious, safe and affordable drugs is of high importance. Vernonia lasiopus O. Hoffm., an indigenous African plant of the Asteraceae family, has been extensively reported to be used ethno-medicinally as a treatment for malaria. Its crude extracts obtained with solvents of different polarity were screened in vitro for anti-protozoal activity and the dichloromethane extract was found to be particularly active against Trypanosoma brucei rhodesiense (IC 50 = 0.17 µg/mL). Bioassay-guided chromatographic fractionation of the dichloromethane extract led to the isolation and identification of six elemanolide type sesquiterpene lactones: 8-desacylvernolide, vernolepin, vernomenin, vernodalol, vernodalin and 11,13-dihydrovernodalin. All these elemanolide sesquiterpene lactones showed in vitro anti-trypanosomal activity. They were also tested for cytotoxicity against mammalian cells (L6 cell line). Vernolepin, the main component in the extract, was also the most potent with an IC 50 value of 0.05 µg/mL against T.b. rhodesiense trypomastigotes. This compound showed a selectivity index of 14.5, which makes it an interesting candidate for in vivo tests and determination of its mechanism of action.

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., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

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.

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.

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 M(2) 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 LC(50) and LC(90) 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 farvorably with the commercial larvicide pylarvex® that showed 100% mortality at the same concentration. Compound 3 was less potent and had an LC(50) 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.