Enhanced production of unusual triterpenoids from Kadsura angustifolia fermented by a symbiont endophytic fungus, Penicillium sp. SWUKD4.1850

Highly oxygenated schitriterpenoids are interesting for study of their structures, bioactivities and synthesis. From Kadsura angustifolia fermented by an associated symbiotic endophytic fungus, Penicillium sp. SWUKD4.1850, nine undescribed triterpenoids, kadhenrischinins A-H, and 7β-schinalactone C together with four known triterpenoids, henrischinins A and B, schinalactone C and nigranoic acid were isolated and established by the extensive 1D-, 2D-NMR, HR-ESI-MS and ECD data analysis. Except nigranoic acid, all these metabolites have been first detected in non-fermented K. angustifolia. Structurally, kadhenrischinins A-D belong to the relatively rare class of highly oxygenated schitriterpenoids that contain a unique 3-one-2-oxabicyclo [3,2,1]-octane motif, while kadhenrischinins E-H feature a cyclopentane ring in a side chain rarely found in the family Schisandraceae. These results indicated that fermentation of K. angustifolia with SWUKD4.1850 induced the production of highly oxygenated schitriterpenoids from nigranoic acid, which provided a guidance to obtain desired compounds from those plants initially thought not to produce. This is the first report on the fermentation of K. angustifolia medical plant and the first discovery of highly oxygenated schitriterpenoids by microbial technology. [Display omitted] •Nine undiscribed triterpenoids, kadhenrischinins A-H and 7β-schinalactone C were isolated from fermented Kadsura angustifolia.•Their structures were elucidated by extensive spectroscopic analysis.•Kadhenrischinins A-H belong to rare 21, 24-cyclo-3, 4: 9, 10-disecocycloartene highly oxygenated triterpenoids.•The proposed biosynthetic pathways of all the compounds were drawn and are presented in this paper.•This is the first report on the discovery of highly oxygenated schitriterpenoids by microbial technology.