Chemical and biological explorations of the electrophilic reactivity of the bioactive marine natural product halenaquinone with biomimetic nucleophiles

The electrophilic reactivity of the bioactive marine Sponge natural product halenaquinone has been investigated by reaction with the biomimetic nucleophiles N-acetyl-L-cysteine and N(α)-acetyl-L-lysine. While cysteine reacted at the vacant quinone positions C-14 and C-15, lysine was found to react preferentially at the keto-furan position C-1. A small library of analogues was prepared by reaction of halenaquinone with primary amines, and evaluated against a range of biological targets including Phospholipase A(2), farnesyltransferases (FTases) and Plasmodium falciparum. Geranylamine analogue 11 exhibited the most potent activity towards FTases (IC(50) 0.017-0.031 μM) and malaria (IC(50) 0.53-0.62 μM).