A new sesquiterpene from the entomogenous fungus Phomopsis amygdali

A new sesquiterpene, (+)- S -1-methyl-abscisic-6-acid ( 1 ), together with five known compounds, (+)- S -abscisic acid ( 2 ), fusicoccin J ( 3 ), 3α-hydroxyfusicoccin J ( 4 ), ( R )-5-hydroxymethylmellein ( 5 ) and 4-hydroxyphenethyl acetate ( 6 ) was isolated from the fermentation extract of Phomopsis amygdali , an entomogenous fungus isolated from Call midge . Their structures were determined mainly by analysis of MS and NMR spectroscopic data.

Compounds 1 – 6 were tested for antimicrobial activity against three plant pathogenic fungi: Gibberella zeae , Verticillium albo-atrum , and Fusarium nivale , and two bacteria: Escherichia coli and Pseudomonas aeruginosa 2033E. As a result, compounds 1 – 4 displayed antibacterial activity against Gram-negative P. aeruginosa 2033E, and the minimum inhibition concentration (MIC value) of 1 – 4 is 30 μg/mL, 58 μg/mL, 26 μg/mL, and 26 μg/mL, respectively.