In vitro antiplasmodial and cytotoxicity activities of crude extracts and major compounds from Goniothalamus lanceolatus.

ETHNOPHARMACOLOGICAL RELEVANCE: Malaria, a devastating infectious disease which was initially recognized as episodic fever, is caused by parasitic protozoan of the genus Plasmodium. Medicinal plants with ethnobotanical information to treat fever and/or malaria has been the key element in identifying potential plant candidates for antimalarial screening. Goniothalamus lanceolatus Miq. (Annonaceae) is used as a folk remedy, particularly to treat fever and skin diseases. AIM OF THE STUDY: In this context, supported with previous preliminary data of its antiplasmodial activity, this study was undertaken to determine the in vitro antiplasmodial and cytotoxicity activities of G. lanceolatus crude extracts and its major compounds. MATERIALS AND METHODS: The in vitro antiplasmodial activity was determined by parasite lactate dehydrogenase (pLDH) assay on chloroquine-sensitive (3D7) and chloroquine-resistant (K1) strains of Plasmodium falciparum. The cytotoxicity activity was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on hepatocellular carcinoma (HepG2) and normal liver (WRL-68) cell lines. RESULTS: The root methanol extract possessed potent antiplasmodial activity against both P. falciparum 3D7 and K1 strains (IC50 = 2.7 µg/ml, SI = 140; IC50 = 1.7 µg/ml, SI = 236). Apart from the DCM extract of stem bark and root that were found to be inactive (IC50 > 50 µg/ml) against 3D7 strain, all other tested crude extracts exhibited promising (5< IC50 < 15 µg/ml) to moderate (15< IC50 < 50 µg/ml) antiplasmodial activity against both strain. Additionally, only compound C (Parvistone D) exerted promising antiplasmodial activity against 3D7 strain (IC50 = 7.5 µM, SI = 51) whereas compound A, B and D showed moderate antiplasmodial activity against the same strain (20 < IC50 < 100 µM). Interestingly, when tested on K1 strain, compound A, C and D exhibited promising antiplasmodial activity (2 < IC50 < 20 µM) while compound B exhibited moderate activity (IC50 = 26.9 µM). Cytotoxicity study showed that all tested crude extracts and compounds were non-toxic on WRL-68 and HepG2 cell lines (CC50 > 30 µg/ml, CC50 > 10 µM, respectively), except for the hexane and DCM extracts of root, which exerted mild cytotoxicity on HepG2 cell line (IC50 < 30 µg/ml). CONCLUSIONS: This study suggests that the root methanol extract and compound C (Parvistone D) obtained from G. lanceolatus are highly potential for exploitation as source of antimalarial agents. Parvistone D is identified as one of the bioactive styryl lactones found in the plant extract. It is also noteworthy, that the extract and compound were more active against chloroquine-resistant (K1) strain of P. falciparum. Further studies are being carried out to assess their toxicity profile and antimalarial efficacy in animal model.

The Antimalarial Effect of Curcumin Is Mediated by the Inhibition of Glycogen Synthase Kinase-3ß.

Curcumin, a bioactive compound in Curcuma longa, exhibits various pharmacological activities, including antimalarial effects. In silico docking simulation studies suggest that curcumin possesses glycogen synthase kinase-3ß (GSK3ß)-inhibitory properties. The involvement of GSK3 in the antimalarial effects in vivo is yet to be demonstrated. In this study, we aimed to evaluate whether the antimalarial effects of curcumin involve phosphorylation of host GSK3ß. Intraperitoneal administration of curcumin into Plasmodium berghei NK65-infected mice resulted in dose-dependent chemosuppression of parasitemia development. At the highest dose tested (30 mg/kg body weight), both therapeutic and prophylactic administrations of curcumin resulted in suppression exceeding 50% and improved median survival time of infected mice compared to control. Western analysis revealed a 5.5-fold (therapeutic group) and 1.8-fold (prophylactic group) increase in phosphorylation of Ser 9 GSK3ß and 1.6-fold (therapeutic group) and 1.7-fold (prophylactic group) increase in Ser 473 Akt in liver of curcumin-treated infected animals. Following P. berghei infection, levels of pro- and anti-inflammatory cytokines, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-10, and IL-4 were elevated by 7.5-, 35.0-, 33.0-, and 2.2-fold, respectively. Curcumin treatment (therapeutic) caused a significant decrease (by 6.0- and 2.0-fold, respectively) in serum TNF-α and IFN-γ level, while IL-10 and IL-4 were elevated (by 1.4- and 1.8-fold). Findings from the present study demonstrate for the first time that the antimalarial action of curcumin involved inhibition of GSK3ß.