Production of phenylacetic acid derivatives and 4-epiradicinol in culture by Curvularia lunata

Phenylacetic acid derivatives 1, 3, 4 and epiradicinol ( 5) have been isolated from the culture mycelia of Curvularia lunata grown on YMG, a medium consisting of yeast, glucose and malt extract. Compounds 1, 3 and 4 lack antimicrobial and antioxidant properties but 5 is significantly antibacterial. The absolute configuration of the diol in 5 was determined by acetonide derivative methodology. Phenylacetic acid derivatives, methyl 2-acetyl-3,5-dihydroxyphenylacetate ( 1) and methyl 2-acetyl-5-hydroxy-3-methoxyphenylacetate ( 3); curvulin or ethyl 2-acetyl-3,5-dihydroxyphenylacetate ( 4), a known metabolite of Curvularia siddiqui, and 4-epiradicinol ( 5) have been isolated from the culture mycelia of Curvularia lunata grown on YMG, a medium consisting of yeast, malt extract and glucose. Compounds 1, 3 and 4 lack antimicrobial and antioxidant activity, but 4-epiradicinol ( 5) inhibited the growth of Escherichia coli, Staphylococcus aureus, Salmonella choleraesuis and Bacillus subtilis. The structures of compounds 1, 3– 5 were determined by analyses of IR, MS, 1D and 2D NMR data, assisted by chemical shift comparison to related and model compounds. The relative stereochemistry of the vicinal diol in 5 was determined from the 1H NMR signals for the methyl protons of the resulting cyclic acetonide prepared from 5.