Seven undescribed guaiane-type sesquiterpenoids named biscogniauxiaols A-G (1-7) were isolated from the endophytic fungus Biscogniauxia petrensis on Dendrobium orchids. Their structures were determined by extensive spectroscopic analyses, electronic circular dichroism (EC) and specific rotation (SR) calculations. Compound 1 represented a new family of guaiane-type sesquiterpenoids featuring an unprecedented [5/6/6/7] tetracyclic system. A plausible biosynthetic pathway for compounds 1-7 was proposed. The anti-fungal, anti-inflammatory and multidrug resistance reversal activities of the isolates were evaluated. Compounds 1, 2 and 7 exhibited potent inhibitory activities against Candida albicans with MIC values ranging from 1.60 to 6.30 μM, and suppressed nitric oxide (NO) production with IC50 ranging from 4.60 to 20.00 μM. Additionally, all compounds (100 μg/mL) enhanced the cytotoxicity of cisplatin in cisplatin-resistant non-small cell lung cancer cells (A549/DDP). This study opened up a new source for obtaining bioactive guaiane-type sesquiterpenoids and compounds 1, 2, and 7 were promising for further optimization as multifunctional inhibitors for anti-fungal (C. albicans) and anti-inflammatory purposes.
Keywords: Biscogniauxia petrensis; anti-fungal activity; anti-inflammatory activity; endophytic fungus; multidrug resistance reversal activity; sesquiterpenoids.