Screening For New Metabolites Research Articles

Skeletocutins M-Q: biologically active compounds from the fruiting bodies of the basidiomycete Skeletocutis sp. collected in Africa.

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.

Minutellins A – D, azaphilones from the stromata of Annulohypoxylon minutellum (Xylariaceae)

During the course of our screening for new metabolites with chemotaxonomic importance from stromata of fungi from the family Xylariaceae, we characterized several interesting metabolites in the fungus Annulohypoxylon minutellum. Extraction of the fruiting bodies and purification by preparative HPLC resulted in the isolation of five metabolites. The main compound was identified as the known metabolite hinnulin A (5), while four minor compounds were found to represent previously undescribed azaphilones, named minutellins A – D (1–4). Their planar structures were elucidated using NMR and HRESIMS data; absolute stereochemistry was assigned by CD data and Mosher's method. Compounds 1, 3 and 5 showed cytotoxic effects against murine and human cells. As the production of 1–5 is restricted to a group of closely related Annulohypoxylon species, they serve well as chemotaxonomic marker.

Bipolamides A and B, triene amides isolated from the endophytic fungus Bipolaris sp. MU34

As a result of the continued screening for new metabolites produced by endophytic fungi from Thai medicinal plants, two new triene fatty acid amides, bipolamides A (1) and B (2), were discovered from the endophytic fungus Bipolaris sp. MU34. The structures of all of the isolated compounds were elucidated on the basis of the spectroscopic data of NMR and MS. An antimicrobial assay revealed that bipolamide B (2) had moderate antifungal activity against Cladosporium cladosporioides FERMS-9, Cladosporium cucumerinum NBRC 6370, Saccharomyces cerevisiae ATCC 9804, Aspergillus niger ATCC 6275 and Rhisopus oryzae ATCC 10404, with Minimum inhibitory concentration (MIC) values of 16, 32, 32, 64 and 64 μg ml(-1), respectively.

Agesamides A and B, Bromopyrrole Alkaloids from Sponge Agelas Species: Application of DOSY for Chemical Screening of New Metabolites.

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Metabolic products of microorganisms

In the course of a screening for new metabolites from fungi we isolated a substance with antimicrobial activity from cultures of Aspergillus duricaulis (CBS 481.65) (Tü 679). It was antagonized by putrescine, spermidine, spermine, arginine, citrulline, lysine, ornithine, in higher concentration by aspraagine and glutamine too. The effect of ethylenediaminetetraacetate on the susceptibility of Streptomyces viridochromogenes (Tü 57) and Bacillus subtilis ATCC 6051 to this antibiotic has been studied. The substance was characterized and identified as cyclopaldic acid.