Microbial Transformation of Yakuchinone A and Cytotoxicity Evaluation of Its Metabolites.

Yakuchinone A () is a bioactive diarylheptanoid isolated from the dried fruits of Microbial transformation has been recognized as an efficient method to produce new biologically active derivatives from natural products. In the present study, microbial transformation of yakuchinone A was performed with the fungus KCTC 26779, which led to the isolation of nine new metabolites (, , , and -). Their structures were elucidated as (3)-oxyphyllacinol (), (3)- and (3)-7-hydroxyoxyphyllacinol ( and ), (3)-oxyphyllacinol-4'--β-d-glucopyranoside (), (3)-4″-hydroxyoxyphyllacinol (), (3)-3″-hydroxyoxyphyllacinol (), (3)-2″-hydroxyoxyphyllacinol (), (3)-2″-hydroxyoxyphyllacinol-2″--β-d-glucopyranoside (), and (3)-oxyphyllacinol-3--β-d-glucopyranoside () based on the comprehensive spectroscopic analyses and the application of modified Mosher's method. All compounds were evaluated for their cytotoxic activities against melanoma, as well as breast, lung, and colorectal cancer cell lines. Compound , which was -glucosylated on the diarylheptanoid alkyl chain, exhibited the most selective cytotoxic activities against melanoma cell lines with the IC values ranging from 6.09 to 9.74 μM, indicating that it might be considered as a possible anti-cancer lead compound.