Abstract:
Bipolarins A-H (
1-8 ), eight new tetracyclic ophiobolin-type sesterterpenes featuring a rare oxaspiro4.4nonane moiety, were isolated from cultures of fungus
Bipolaris sp. TJ403-B1. Their structures and absolute configurations were elucidated by comprehensive spectroscopic analyses, single-crystal X-ray diffraction experiments, electronic circular dichroism and
13C NMR calculations. Additionally, compound
5 exhibited significant selective antimicrobial activity against
Enterococcus faecalis with an MIC value 8 μg·mL
-1.