Scientific validation of anti-malarial activity in Piper longum fruit: an in vitro and in silico study
摘要
Drug resistance in malarial parasite potentiates the discovery of new antimalarial agents. Piper longum fruits find use as a natural remedy against malaria in different parts of India. Therefore, present study aimed to validate the antimalarial activity of the Piper longum fruit extracts using in vitro and in silico approaches. Soxhlet apparatus was used for extract preparation. Antimalarial efficacy was assessed against in vitro blood-stage culture of chloroquine (CQ)-sensitive Plasmodium falciparum strain 3D7. In silico study on fruit phytochemicals was performed using molecular docking. P. falciparum transketolase (PfTk) protein structure was modeled using S. cerevisiae transketolase (PDB 1TRK) as a template. Ramachandran plot, Z-score and knowledge-based energy structure analyses parameters were used to validate the modeled PfTk protein structure that was used for the molecular docking simulation study. The non-polar extracts showed comparatively better antimalarial activity (IC50 10.08 ± 0.75–1.91 ± 0.08 µg/ml). Two phytochemicals viz., retrofactamide A and B showed potential binding (−7.43 and − 8.04 kcal/mole, respectively) at the active site of the modeled PfTk protein. Both the compounds interacted with some of the common amino acid residues (Gly429, Lys58, Phe318, Tyr311, Trp314, and Phe336). The predicted IC50 concentration of retrofactamide A and B against PfTk protein was 2.932 and 3.385 µM, respectively. The lead phytochemicals showed better pharmacokinetics and physicochemical properties in terms of drug-likeness, water-solubility, bioavailability, and absorption in comparison to standard inhibitors. The study demonstrated that P. longum possessed strong antimalarial activity in vitro and its phytochemicals retrofactamide A and B exhibited potent inhibitory action against PfTk in silico.