Biotransformation of p-coumaric acid (=(2E)-3-(4-Hydroxyphenyl)prop-2-enoic acid) by Momordica charantia peroxidase

LC/MS3-Guided biotransformation of p-coumaric acid (=(2E)-3-(4-hydroxyphenyl)prop-2-enoic acid: CA) with H2O2/Momordica charantia peroxidase at pH 5.0 and 45 degrees in the presence of acetone has resulted in the isolation of three CA trimers, triCA1 (1). triCA2 (trans-2), and triCA3 (cis-2), and seven CA dimers, diCA1 - diCA7, i.e., 3-9, among which seven (triCA1-triCA3 and diCA1-diCA4) are new compounds and three (diCA5-diCA7) are known compounds. The structures were established by 2D-NMR such as HSQC, HMBC, and NOESY measurements. The possible mechanism for the formation of the products is also discussed (Schemes 1-3). This is the first time that the biotansformation of p-coumaric acid catalyzed by peroxidase in vitro was achieved. Compounds triCA3 (cis-2), diCA1 (3), diCA5 (7), and diCA7 (9) exhibit a stronger antioxidative activity than the parent CA.