Search

Four prenylated indole alkaloids (1−4) were targeted isolated from the mangrove rhizosphere soil-derived fungus Penicillium janthinellum HK1-6 by using molecular networking strategies. Among them, the planar structure and relative configuration of notoamide X (1) were elucidated by detailed analysis of the spectroscopic data especially the NOESY spectrum for the first time and its absolute configuration was determined by ECD spectrum. Furthermore, curated molecular networks of MS/MS data were generated with GNPS which allowed highlighting six prenylated indole alkaloids (5, 6, 8, 9, 11, 12) that had not previously been identified in this fungus and two (7, 10) that had never been observed in any fungus. The MS/MS fragmentation pathway of these prenylated indole alkaloids was summarized. [ABSTRACT FROM AUTHOR]

The marine-derived Aspergillus protuberus MF297-2 and the terrestrial A. amoenus NRRL 35600 produce enantiomeric prenylated indole alkaloids. Investigation of biological activities of the natural and synthetic derivatives revealed that (−)-enantiomers of notoamides A and B, 6- epi -notoamide T, and stephacidin A inhibited receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)–induced osteoclastogenic differentiation of murine RAW264 cells more strongly than their respective (+)-enantiomers. Among them, (−)-6- epi -notoamide T was the most potent inhibitor with an IC 50 value of 1.7 μM. [ABSTRACT FROM AUTHOR]

Two new prenylated indole alkaloids, named Speramides A ( 1 ) and B ( 2 ) were isolated from the extraction of the freshwater-derived fungus Aspergillus ochraceus KM007 . Their structures were elucidated by means of spectroscopic analysis. Compound 1 is the first prenylated brevianamide derivative. These compounds isolated were evaluated for their antimicrobial activity, among which, compound 1 showed moderate activity against Pseudomonas aeruginosa with a MIC value of 0.8 μM. [ABSTRACT FROM AUTHOR]

We previously described the bioconversion of Notoamide T into (+)-Stephacidin A and (−)-Notoamide B, which suggested that Versicolamide B ( 8 ) is biosynthesized from 6- epi -Notoamide T ( 10 ) via 6- epi -Stephacidin A. Here we report that [ 13 C] 2 - 10 was incorporated into isotopically enriched 8 and seven new metabolites, which were not produced under normal culture conditions. The results suggest that the addition of excess precursor activated the expression of dormant tailoring genes giving rise to these structurally unprecedented metabolites. [ABSTRACT FROM AUTHOR]

The fungal indole alkaloids are a unique class of complex molecules that have a characteristic bicyclo[2.2.2]diazaoctane ring and frequently contain a spiro-oxindole moiety. While various strains produce these compounds, an intriguing case involves the formation of individual antipodes by two unique species of fungi in the generation of the potent anticancer agents (+)- and (-)-notoamide A. NotI and NotI' have been characterized as flavin-dependent monooxygenases that catalyze epoxidation and semi-pinacol rearrangement to form the spiro-oxindole center within these molecules. This work elucidates a key step in the biosynthesis of the notoamides and provides an evolutionary hypothesis regarding a common ancestor for production of enantiopure notoamides., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)