Discovery of potential RdRp catalytic domain inhibitors against Crimean-Congo hemorrhagic fever virus from Andrographis paniculata via LC-MS/MS profiling and computational approaches.

Crimean-Congo hemorrhagic fever virus (CCHFV) is a highly pathogenic zoonotic virus associated with significant mortality and currently lacks FDA-approved therapeutic options. Owing to its endemic nature and epidemic potential, it has been included in WHO priority pathogen list under its R&D Blueprint, highlighting the urgent need for development of novel antiviral agents. The present study explores antiviral potential of phytoconstituents from Andrographis paniculata targeting viral catalytic domain of RNA-dependent RNA polymerase (RdRp). Cold Ethanolic leaf extract was prepared using ultrasonic-assisted extraction and subjected to LC-MS/MS QQQ profiling, leading to identification of 44 phytochemicals, mostly andrographolide diterpenes lactones and flavonoids. Among these, 11 major compounds were selected based on abundance and spectral reliability for computational evaluation. Molecular docking revealed strong binding affinities of bisandrographolide (- 8.212 kcal/mol), andrographiside (- 7.659 kcal/mol), 3-O-β-D-glucopyranosyl-andrographolide (- 7.653 kcal/mol), andrographidin A (- 7.540 kcal/mol) and neoandrographolide (- 7.353 kcal/mol) towards the catalytic domain of RdRp which is comparable to standard Ribavirin (- 8.314 kcal/mol). MD simulations of 100 ns were performed which demonstrated stable Andrographis paniculata ligand-RdRp complexes through consistent RMSD, RMSF, radius of gyration, hydrogen bonding, minimum distance (~ 0.25-0.30 nm) and SASA profiles, except for neoandrographolide, showed comparatively lower conformational stability. In silico ADMET analysis indicated generally acceptable pharmacokinetic and safety profiles, although some compounds exhibited low GIT absorption. Collectively, results suggest that Andrographis paniculata phytoconstituents, particularly andrographolide diterpenes lactones possess promising inhibitory potential against catalytic domain of CCHFV RdRp and may serve as lead candidates for antiviral drug development. Further mechanistic studies are needed to elucidate exact mode of RdRp catalytic domain inhibition while in vitro and in vivo validation is crucial to confirm their therapeutic potential and translational relevance.