Rogersonins A and B, Imidazolone N-Oxide-Incorporating Indole Alkaloids from a verG Disruption Mutant of Clonostachys rogersoniana

Abstract

Rogersonins A (1) and B (2), two new indole alkaloid–polyketide hybrids, have been isolated from cultures of a verG disruption mutant of the Cordyceps-colonizing fungus Clonostachys rogersoniana; their structures were elucidated primarily by NMR experiments. The absolute configurations of 1 and 2 were assigned using the modified Mosher method and via electronic circular dichroism and NMR calculations. Compounds 1 and 2 incorporate an imidazolone N-oxide moiety that has not been reported in any natural products.

Metabolites from Clonostachys Fungi and Their Biological Activities

“…Y1085 - [17] Gliocladicillin A (32) Bionectria sp. Y1085 - [17] Gliocladicillin C (33) Bionectria sp. Y1085 Antibacterial activity [17] Clonostachys rogersoniana Cytotoxic activity [20] Gliocladin A (34) Glicladium roseum OUPS-N132 - [21] Gliocladin B (35) Glicladium roseum OUPS-N132 - [21] Gliocladin C (36) Glicladium roseum OUPS-N132 Cytotoxic activity [21] Gliocladium roseum YMF1.00133…”

“…These two compounds showed moderate antibacterial activity on Klebsiella pneumonia and Bacillus subtlilis [32]. Similarly, rogersonins A (69) and B (70) were two indole-polyketide hydrids isolated from verG disruption mutant of Clonostachys rogersoniana [33]. Blocking the biosynthesis of secondary metabolites through the disuption of the biosynthesis-related genes provide a method to activate cryptic or silent secondary metabolites in fungi.…”

“…In order to search for new bioactive metabolites from Clonostachy fungi, some strategies, such as gene disruption, modification of the fermentation medium, co-cultivation and synthetic modification, have been proven to be effective. Gliocladiosins A (67) and B (68), as well as rogersonins A (69) and B (70) were alkaloid-polyketide hydrids isolated from gene disruption mutants of Clonostachys rogersoniana [32,33]. Fermentation of the Clonostachys rosea on white beans instead of rice afforded one γ-lactam clonostalactam (62) and two γ-lactones 3,5-dihydroxyfuran-2(5H)-one (141) and sapinofuranone B (142) that were not detected in the former extracts [11].…”

Sarcosenones A–C, highly oxygenated pimarane diterpenoids from an endolichenic fungus Sarcosomataceae sp.

“…The absolute congurations of 1 were deduced by comparison of the experimental and simulated electronic circular dichroism (ECD) spectra calculated using the time-dependent density functional theory (TDDFT). 29 The ECD spectra of the four possible enantiomers 1a-d ( Fig. S11 †) were calculated.…”

Pseudonectrins A–D, heptaketides from an endophytic fungus Nectria pseudotrichia

“…The absolute conguration of 1 was deduced by comparison of the experimental and simulated electronic circular dichroism (ECD) spectra calculated using the time-dependent density functional theory (TDDFT). 32 The ECD spectra of the two possible enantiomers 1a and 1b ( Fig. S25 †) were calculated.…”