Furanofuran lignan metabolism as a function of seed maturation in sesamum indicum: methylenedioxy bridge formation

Abstract

Sesamum indicum seeds accumulate the antioxidant lignans, (+)-sesamin and (+)-sesamolin. It was established that seeds of 8-week old S. indicum plants catalyzed distinct lignan transformations (methylenedioxy bridge formation in piperitol and sesamin, as well as oxygen insertion in sesamolin) depending upon the stage of seed maturity, i.e. lignan formation was developmentally regulated. The most mature seeds at the eight week developmental stage efficiently converted (+)-[3,3′-O14CH3] pinoresinol into (+)-piperitol and (+)-sesamin, whereas younger seeds had a higher conversion into (+)-sesamolin; the corresponding (−)-[3,3′-O14CH3] pinoresinol antipode was not metabolized. Microsomal preparations obtained from S. indicum seeds catalyzed methylenedioxy bridge formation via an O2\\NADPH\\cytochrome P-450 dependent transformation of (+)-pinoresinol into (+)-piperitol. Preliminary characterization of the enzyme established its cytochrome P-450 dependence.