Further study on Penares sp. from Vietnamese waters: Minor lanostane and nor-lanostane triterpenes

•The lanostane derivatives of the Vietnamese Penares sp. were investigated.•Eight new oxidated triterpenoids were isolated and structurally described.•The biogenetic correlation of triterpene metabolites in Penares and Erylus spp. was discussed.

Eight new oxidized lanostane and nor-lanostane derivatives (1–8) along with the previously known penasterol (9) and 24-ethylcholesta-4,24(28)-dien-3-one (10) were isolated from a sponge Penares sp. collected from the Vietnamese waters. Structures of these minor compounds were elucidated by the detailed NMR spectroscopic and mass-spectrometric analyses and by comparison with earlier reported spectroscopic data. A hypothetic scheme of metabolism of the lanostane derivatives in sponges belonging to Penares and Erylus genera was proposed and discussed.

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