Anti-proliferative ambuic acid derivatives from Hawaiian endophytic fungus Pestalotiopsis sp. FT172

Bioassay-guided fractionation of an extract from a Hawaiian endophytic fungus Pestalotiopsis sp. FT172 led to the isolation of eight compounds, including five previously undescribed ambuic acid derivatives pestallic acids A-E. Their chemical structures were determined by HRMS and NMR spectroscopy. All isolates were evaluated for their anti-proliferative activity against A2780 and cisplatin-resistant A2780 (A2780CisR) cancer cell lines. Pestallic acid E showed potent anti-proliferative activity against A2780 and A2780CisR cell lines with IC50 values of 3.3 and 5.1 μM, respectively, and (+)-ambuic acid demonstrated inhibitory activity against the above two cancer cell lines with IC50 values of 10.1 and 17.0 μM, respectively.124