UNCOVERING THE POTENTIAL OF NIRAGA TEA POLYHERBALTM AS AN ANTIOXIDANT AND ANTIVIRAL AGENT AGAINST DENGUE: INSIGHTS FROM IN VITRO AND IN SILICO APPROACHES

Abstract

Dengue is a vector-borne disease with a high health burden in tropical regions, yet no specific antiviral therapy is currently available. This study aimed to investigate the antioxidant activity, cytotoxicity, and antiviral activity against dengue virus serotype 2 (DENV-2) of the Niraga Tea Polyherbal^TM formulation and performed phytochemical profiling and molecular docking. GC‒MS and FT‒IR analyses were used to analyze the profiles and structures of bioactive compounds; antioxidant activity was evaluated using the DPPH, ABTS, and FRAP methods; dengue antiviral activity was evaluated using the Viral ToxGlo assay; and cytotoxicity was evaluated using Vero cells in an MTT assay. Molecular docking evaluations of the compounds targeting the DENV-2 NS5 protein in silico. GC‒MS characterization revealed 100 compounds, predominantly methyl oleate (69.60%) and ethyl pentadecanoate (20.84%), along with quercetin (0.46%) and epigallocatechin gallate (0.19%). FT-IR analysis confirmed that phenolic hydroxyl groups were the dominant functional groups. DPPH, ABTS, and FRAP assays revealed IC₅₀ values of 20.79, 21.34, and 18.80 µg/mL, respectively. MTT assays of Vero cells yielded a CC₅₀ value of 1207 µg/mL. Niraga Tea Polyherbal^TM significantly inhibited the cytopathic effects (F= 42.50; p=0.005), with an EC₅₀ of 10.32 µg/mL and a selectivity index (SI) of 116.96 against DENV-2. Molecular binding studies of methyl oleate and ethyl pentadecanoate to DENV-2 NS5 revealed weak binding affinities (ΔG -3.95 to -4.31 kcal/mol), which were weaker than those observed with more potent in vitro compounds. In conclusion, Niraga Tea Polyherbal^TM has the potential to be developed as a candidate phytopharmaceutical for dengue antiviral therapy with a high safety profile against host cells.