Enhancement of the antiplasmodial activity of quassin by transformation into a gamma-lactone.

The naturally occurring bitter principle quassin (1) was converted chemically into the gamma-lactone quassilactone (13) in an attempt to enhance its antiplasmodial activity. The in vitro antiplasmodial activity of 13 against Plasmodium falciparum (K1) (IC(50) = 23 microM) was 40-fold greater than that of 1. However, one of the intermediates, compound 8, the 15beta-hydroxy,16-O-m-chlorobenzoyl analogue of 1, was 506-fold more active than 1 against P.

The quantification of citral in lemongrass and lemon oils by near-infrared spectroscopy.

Previous work has demonstrated the capability of near-infrared (NIR) spectroscopy to determine the cineole content (not less than 70% w/w) of eucalyptus oil with an accuracy comparable with that of the British Pharmacopoeia (BP) assay method. The aim of the present study was to determine if the same method was capable of quantifying other chemical constituents at similar levels in essential oils and also to ascertain if NIR spectroscopy can accurately quantify compounds present at much lower levels in essential oils. Lemongrass oil contains citral at concentrations of approximately 65-85% w/w, and lemon oil contains citral at a concentration of approximately 2-5% w/w.