Pennigritrem, a naturally-occurring penitrem A analogue with novel cyclisation in the diterpenoid moiety

Abstract

A prominent novel analogue of penitrem A has been resolved from the tremorgenic alkaloids of a strain of Penicillium nigricans and the structure, elucidated by NMR spectroscopy, shown to involve the terminal diterpenoid isoprene in a cyclisation which is unique amongst fungal indolediterpenoids. Consequent conformational changes in the biologically active moiety significantly reduced tremorgenicity.