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.
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.
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.
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,
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.
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