Pharmacognosical evaluation of the bioactive principles of ganiothalmus scortechinii as potential new anti-plasmodials

A bioassay guided fractionation of Ganiothalamus scortechinii yielded compounds with promising anti-malarial activity. When subjected to the lactate dehydrogenase calanone, goniothalamine, goniothalenol and pinocembrine, the showed an improved schizonticidal activity with the chloroquine sensitive strain of Plasmodium falciparum, compared to the crude extract of G. scortechinii; whilst only goniothalamine and goniothalanol were active with the resistant strain (Gombak A). The cytotoxicity of each compound were then assessed with the MTT test using MDBK cells. Out of the four compounds only calanone exhibited a safe therapeutic margin, whilst the others are found to be toxic against the cells used. In the attempt to characterise its anti-malarial activity the beta haematin (BH) inhibitory activity of the compounds were determined using the Haematin Polymerisation Inhibitory Assay (HPIA) and the Beta Haematin Inhibitory Assay (BHIA). For each, a better inhibition was observed in the HPIA. However from the low inhibitory values obtained it can be concluded that the inhibition of BH formation is not how the compounds exert their antimalarial activity. (Author)