Bioconversion of curcumin and its analogs

Reduction of curcumin (1), a chemopreventive agent from Turmeric (Curcuma longa L.), yielded five products. The three major compounds were identified as 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 compound (3) as the sole metabolite. Bioconversion of curcumin (1) with Rhizopus oryzae ATCC 11145 yielded 1,7-bis(4-hydroxy-3-methoxyphenyl)hept-1-en-3,5-dione (5) and metabolites 3 and 4. Metabolite 2 was not produced. No transformation of curcumin (1) was observed with Aspergillus niger ATCC 16888. The bioactivities and structural elucidation of these metabolites are reported herein.