Biotransformation of sinapic acid catalyzed by Momordica charantia peroxidase

Biotransformation of sinapic acid (1) with H2O2/Momordica charantia peroxidase, which exists in the widely used food M. charantia, at pH 5.0, 43 degrees C, in the presence of acetone resulted in six compounds, including four new compounds. Compound 2 was the first isolation of a new unique sinapic acid tetrameric derivate, which is formed by peroxidase catalysis in vitro. Besides 2, three other new sinapic acid dimers, 3-5 have also been isolated. Their structures were established on the basis of spectroscopic data. Compound 5 showed a stronger antioxidative activity than the parent sinapic acid (1). Compounds 4 and 5 significantly inhibited the growth of HL-60 cell at the concentration of 10(-5) mol/L.