Structure Elucidation of Two New Sesquiterpenoids From <scp> <i>Streptomyces argenteolus</i> </scp> Isolated From <i>Pantholops hodgsoni</i> Feces

Two new sesquiterpenoids, neopinguisane-2β,5β-diol (1) (pinguisane-type) and isoseiricardine B (2) (seiricardine-type), along with two known compounds, pentalenic acid (3) and nakienone C (4), were isolated from the culture broth of Streptomyces argenteolus derived from Pantholops hodgsoni feces. Structures of new compounds 1 and 2 were elucidated through comprehensive analysis of 1D and 2D NMR spectroscopic data. The stereochemistry at C-10 of compound 2 could not be determined due to insufficient sample quantity. This study represents the first reported isolation of both pinguisane-type and seiricardine-type sesquiterpenoids from Streptomyces species. In addition, the antimicrobial activities of all isolated compounds were evaluated.