PHYTOCHEMICAL PROFILING AND EVALUATION OF IN VITRO ANTIOXIDANT AND IN VITRO/IN SILICO ANTIBACTERIAL ACTIVITIES OF CYMBOPOGON CITRATUS (DC.) STAPF LEAF EXTRACT AND ITS BIOACTIVE PHYTOCHEMICALS

Abstract

Cymbopogon citratus (DC.) Stapf is widely recognized for ethnomedicinal value, yet integrated evidence combining phytochemistry, antimicrobial testing, and computational validation remains limited. Leaf powders were extracted with methanol, ethanol, hexane, and water (1:10, 72 h). Qualitative metabolite screening, total phenolic (TPC), flavonoid (TFC), tannin (TTC), and protein estimation were performed. Antibacterial potential was evaluated by agar well diffusion. LC–MS characterized major constituents. Identified ligands were docked against bacterial proteins (1BVR, 1ENY, 1HZP, 6Y80) using AutoDock. The best complex underwent 100 ns molecular dynamics (MD) simulation and MM-GBSA free-energy estimation. Methanol extracted the widest spectrum of phytochemicals. TPC ranged from 42.0 ± 0.001 to 191.3 ± 0.002 µg/ml, TFC from 249.9 ± 0.003 to 994.0 ± 0.010 µg/ml, TTC from 227.5 ± 0.008 to 984.1 ± 0.063 µg/ml, and total protein from 248.2 ± 0.011 to 1070.9 ± 0.051 µg/ml. Zones of inhibition reached 12.5 mm for S. aureus, 11 mm for Klebsiella, 11 mm for P. aeruginosa, and 13 mm for Bacillus. LC–MS revealed monoterpenes, sesquiterpenes, and flavonoids, with farnesol prominent. Docking showed farnesol had the strongest affinity, especially with 1HZP (−6.7 kcal/mol). MD confirmed stability (protein RMSD ≈3.0 Å; ligand RMSD ≈2.8 Å), reduced Rg (19.7→19.4 Å), and persistent H-bonding. MM-GBSA yielded ΔG_bind −66.04 ± 2.63 kcal/mol, dominated by van der Waals and lipophilic terms. Polar extracts of lemon grass are rich in bioactives with measurable antibacterial activity, while in silico analyses identify farnesol as a stable, high-affinity inhibitor warranting further biological validation.