Toxicity and plant growth regulator effects of cytochalasin H isolated from Phomopsis sp.

Abstract

A biologically active metabolite was found in crude extracts of an unidentified species of Phomopsis isolated from weevil-damaged pecans. Purified metabolite was toxic to day-old cockerels, with an LD50 of 12.5 mg/kg, and was markedly inhibitory to growth and floral development of tobacco plants at concentrations of 10−2 to 10−4 M. IR and 1H-nmr spectra indicated an alkylphenyl moiety with a single nitrogen atom present as a secondary amide: and acetate ester, OH, CH3, and a trans-double bond function. Elemental and high-resolution mass-spectral analysis indicated a formula of C30H39NO5 and a molecular weight of 493.2886. The metabolite was identified as cytochalasin H.