Phenylisotertronic acids from the TCM endophytic fungus Phyllosticta sp.

Abstract Four new phenylisotertronic acids ( 1a/1b , 2a , and 3a ) were isolated from a TCM endophytic fungal strain Phyllosticta sp. J13-2-12Y obtained from the leaves of Acorus tatarinowii , along with two known ones ( 2b and 3b ). Compounds 1  −  3 all existed as mixtures of enantiomers, and their corresponding optically pure enantiomers were successfully isolated by chiral HPLC. The structures of isolated compounds were determined by comprehensive spectroscopic analyses and X-ray diffraction. Their absolute configurations were determined by ECD experiments and quantum chemical calculations. In addition, the antimicrobial activities and the cytotoxicities of these three pairs of optically pure enantiomers ( 1a/1b , 2a / 2b , and 3a/3b ) had been evaluated.