Microbial transformation of silybin by Trichoderma koningii

Microbial transformation of silybin A (1) and silybin B (2), the major hepatoprotective flavonolignan diastereomers from the fruits of Silybum marianum, with the culture broth of Trichoderma koningii gave two pairs of glucosylated derivatives. Their structures were identified as silybin A 3-O-β-d-glucopyranoside (3), silybin A 7-O-β-d-glucopyranoside (4), silybin B 3-O-β-d-glucopyranoside (5) and silybin B 7-O-β-d-glucopyranoside (6) by spectroscopic methods.