In-vitro, in-vivo, and in-silico investigation of the traditionally used polyherbal combinations of Coptis teeta, Nyctanthes arbor-tristis, and Andrographis paniculata.

ETHNOPHARMACOLOGICAL SIGNIFICANCE: Coptis teeta, Andrographis paniculata, and Nyctanthes arbor-tristis are widely used in herbal remedies for the treatment of various diseases in Southeast Asia. In Arunachal Pradesh, India, these plants are combined by traditional healers to treat malaria.

AIM OF THE STUDY: The study aimed to evaluate the antimalarial potential of the traditionally used polyherbal combination through in vitro screening against chloroquine-sensitive (Pf3D7) and chloroquine-resistant (PfRKL9) strains of Plasmodium falciparum, and in vivo antimalarial activity against the P. berghei ANKA strain. The study also aimed to study the molecular interactions of putatively detected phytocompounds against P. falciparum dihydrofolate reductase-thymidylate synthase (PfDHFR-TS) using molecular docking and dynamics simulations.

MATERIALS AND METHODS: Taxonomic identification was carried out at the Botanical Survey of India (BSI), Shillong. The cold maceration technique was used to prepare different combinations in different ratios for in-vitro antimalarial screening. Using two concentrations, a preliminary in vitro antimalarial screening was conducted to identify the most potent polyherbal combination. Following this, the most potent combination was subjected to in vitro antimalarial studies, cytotoxicity studies, a blood hemolysis assay, and in vivo studies in P. berghei-infected mice. Liquid chromatography-high-resolution mass spectrometry (LC-HRMS) was performed on the individual extracts to detect putative phytocompounds. In silico studies were done to study the molecular interactions of the putatively identified phytocompounds with PfDHFR-TS.

RESULTS: A combination of powdered rhizomes of C. teeta, leaves of N. arbor-tristis, and aerial parts (leaves and young shoots) of A. paniculata in the ratio 5:2:3 was identified as the most potent polyherbal combination against P. falciparum. The cytotoxicity and blood hemolysis assays confirmed that the combination has negligible toxicity and has no hemolytic effect. Acute toxicity studies showed that the LD50 of the polyherbal combination was greater than 2000 mg/kg body weight. The in-vivo antimalarial study revealed that the polyherbal combination exhibits greater parasite-suppressive activity than the individual extracts but could not outperform the standard drugs. Molecular docking and dynamics simulations revealed that the LC-HRMS-detected compounds (specifically, PubChem CIDs 23786445, 23874507, 38360299, 332427, and 38361380) exhibited stable interactions with PfDHFR-TS and may be one of the contributing factors to the observed antimalarial activity.

CONCLUSION: This study reveals that the traditional practice of using polyherbal combinations rather than individual plants yields greater antimalarial activity. The findings of the study encourage the development of an antimalarial polyherbal formulation after performing pharmacokinetic profiling of these specific computational candidates and extended toxicity studies of the combined polyherbal extract.