Penitremones A–C, Penicillium metabolites containing an oxidised penitrem carbon skeleton giving insight into structure–tremorgenic relationships

A new group of microbial metabolites, designated penitremones A–C, have been characterised by mass spectrometry and 1H and 13C NMR spectroscopy as 10-keto, 11,33-dihydro-variants of the penitrem indole-isoprenoid skeleton. The principal metabolite penitremone A, produced with penitrem A by a Penicillium sp., is an isomer of penitrem E and was also similarly tremorgenic. Reduction of the carbonyl of penitremones A and B with NaHB4 altered tremorgenic activity, thereby indicating potential for new insights into structure–activity relationships in tremorgenic mycotoxins, particularly with respect to neurological disorders in agricultural ruminants caused by the related keto-alkaloid lolitrem B.