Synthesis and Bioconversion of Curcumin Analogs

Abstract

Hydrogenation of curcumin (1), a chemopreventive agent from Turmeric ( Curcuma longa L.) yielded three major compounds: 1,7-bis(4-hydroxy-3-methoxyphenyl)heptane-3,5-dione (2), 5-hydroxy-1,7-bis(4-hydroxy-3-methoxyphenyl)heptan-3-one (3), and 1,7-bis(4-hydroxy-3-methoxyphenyl)heptane-3,5-diol (4). Incubation of compound (2) with Beauveria bassiana ATCC 7159 afforded the hexahydrocurcumin (3) as the sole metabolite while biotransformation of curcumin (1) with B. bassiana gave metabolites 2-4 along with the curcumin-4'-O-4″'-O-methyl-β-D-glucopyranoside (5) and octahydrocurcumin-4'-O-4″'-O-methyl-β-D-glucopyranoside (6). The bioconversion of curcumin (1) with Rhizopus oryzae ATCC 11145 yielded analogs 2-4 while no transformation of curcumin (1) was observed with Aspergillus niger ATCC 16888. The preparation, structural elucidation and biological activities of these metabolites are reported herein.