Microbial transformations of p-coumaric acid by Bacillus megaterium and Curvularia lunata

p-Coumaric acid (1) is an abundant phenolic natural product that exhibits b oth chemoprotectant and antioxidant properties. Microbial transformation sc reening studies showed that 1 was converted to 4-vinylphenol (4), 4-hydroxy benzoic acid (2), caffeic acid (5), protocatechuic acid (6), and other unid entified metabolites over 144 h. 4-Vinylphenol (4) and its dimer, (2R,2S)-4 -(2,3-dihydro-5-hyroxy-2-benzofuranyl) phenol (11), were produced by Bacill us megaterium, and 5-[(E)-2-carboxyethenyl]-2,3-dihydro-2-(4-hydroxyphenyl) -3-benzofurancarboxylic acid (15) and 4-hydroxybenzoic acid (2) were produc ed by Curvularia lunata. On the basis of deuterium-labeling experiments, B. megaterium catalyzes the nonoxidative enzymatic tautomerization of 1 to a vinylogous fi-keto acid intermediate that decarboxylates to 4. The presence of peroxidase and laccase activities in C. lunata extracts suggests that t hese enzymes may be involved in one-electron, p-coumaric acid dimerization in this organism.