Analytical studies on the structure of natural products from menispermaceae drugs

Antiplasmodial activities of a Thai traditional antipyretic formulation, Bencha-Loga-Wichian: A comparative study between the roots and their substitutes, the stems

ETHNOPHARMACOLOGICAL RELEVANCE

Bencha-Loga-Wichian (BLW) is a polyherbal antipyretic formulation that is comprised of Capparis micracantha, Clerodendrum indicum, Ficus racemosa, Harrisonia perforata, and Tiliacora triandra. A traditional medical textbook has documented the use of this formulation for the treatment of many types of fever, including malaria-like fever. Traditionally, BLW is composed of the root parts of those plants. However, in current practice, the stem parts are frequently substituted. Thus, this study aimed to evaluate the antiplasmodial activities of BLW and compare the efficacy between the stem and root parts.

MATERIALS AND METHODS

BLW formulations produced from either the stem or root parts of the various constituent plants as well as the stems or roots of the individual plants were separately extracted and tested against the chloroquine-sensitive (Pf3D7) and -resistant (PfW2) strains Plasmodium falciparum using flow cytometry. The cytotoxicity against peripheral blood mononuclear cells was evaluated using the WST-8 assay to determine the selectivity index (SI). The active compounds of BLW were isolated using antiplasmodial-guided isolation and quantified using Ultra-Performance Liquid Chromatography (UPLC).

RESULTS

The stem and root parts of BLW and the individual plants exhibited antiplasmodial activities at the same levels with good SI values in the range of 3.55-19.74. The extracts of BLW exhibited promising antiplasmodial activity against both Pf3D7 (IC₅₀<5µg/mL) and PfW2 (IC₅₀=6-10µg/mL). Among the five component plants, T. triandra was the most active and exhibited an IC₅₀<5µg/mL against both strains of parasites with SI values >10. We isolated tiliacorinine and yanangcorinine as the major active compounds (IC₅₀<2µg/mL). However, these two compounds demonstrated cytotoxic effects (SI<1). The UPLC analysis identified these compounds in both the stem and root parts of BLW in the range of 0.57-7.66%, which correlated with the antiplasmodial activity. The concentrations of these compounds in BLW, at comparable efficacy, were much less than those at the IC50s for the single compounds alone. It suggested that synergistic interactions increased the antiplasmodial effects as well as alleviated the toxicity of the active compounds in BLW.

CONCLUSION

This study described a promising antiplasmodial activity of BLW that had good selectivity and a toxicity-alleviating effect. The results provided scientific support for the use of this formulation for the treatment of malaria. In addition, the stem and root parts of the plants in BLW exhibited equivalent activities, which indicates the potential for the substitution of the stem parts in the formulation. Thus, we recommend additional study of the stem parts of these plants for further development on the basis of the availability and sustainability.