Phytotoxins from the fungus Malbranchea aurantiaca

Bioassay-directed fractionation of an ethyl acetate extract of the micelial and broth combined extracts of Malbranchea aurantiaca led to the isolation of two phytotoxins, namely, 1-hydroxy-2-oxoeremophil-1(10),7(11),8(9)-trien-12(8)-olide (1) and penicillic acid (2). The structure of compound was established by spectroscopic and X-ray analyses. Metabolites 1 and 2 caused significant inhibition of radicle growth of Amaranthus hypochondriacus with IC50 values of 170.9 and 65.7 μM, respectively. In addition, 1 inhibited the activation of the calmodulin-dependent enzyme cAMP phosphodiesterase.