Cuscuta reflexa Possess Potent Inhibitory Activity Against Human Malaria Parasite: An In Vitro and In Vivo Study

Drug resistance to practically all antimalarial drugs in use necessitate the development of new chemotherapeutics against malaria. In this aspect, traditionally used plants with folklore reputation are the pillar for drug discovery. Cuscuta reflexa being traditionally used in the treatment of malaria in Odisha, India we aimed to experimentally validate its antimalarial potential. Different solvent extracts of C. reflexa or column fractions from a promising solvent extract were evaluated for in vitro anti-plasmodial activity against Plasmodium falciparum strain Pf3D7. Potent fractions were further evaluated for inhibition of parasite growth against different drug resistant strains. Safety of these fractions was determined by in vitro cyto-toxicity, and therapeutic effectiveness was evaluated by suppression of parasitemia and improvement in survival of experimental mice. Besides, their immunomodulatory effect was investigated in Pf-antigen stimulated RAW cells. GCMS fingerprints of active fractions was determined. Column separation of methanol extract which showed the highest in vitro antiplasmodial activity (IC₅₀ = 14.48 μg/ml) resulted in eleven fractions, three of which (F2, F3, and F4) had anti-plasmodial IC₅₀ ranging from ≤ 10 to 2.2 μg/ml against various P. falciparum strains with no demonstration of in vitro cytotoxicity. F4 displayed the highest in vivo parasite suppression, and had a mean survival time similar to artesunate (19.3 vs. 20.6 days). These fractions significantly modulated expression of inflammatory cytokines in Pf-antigen stimulated RAW cells. The findings of the study confirm the antimalarial potential of C. reflexa. Exploration of phyto-molecules in GCMS fingerprints of active fractions is warranted for possible identification of lead anti-malarial phyto-drugs.