Phytochemical profiling, larvicidal activity, and molecular docking of chloris gayana kunth ethanol extract against mosquito vectors

Abstract

ABSTRACT Mosquito-borne diseases continue to pose major global health and economic challenges, compounded by increasing resistance to chemical insecticides. This study explored the larvicidal potential of Cynodon gayana extracts as eco-friendly alternatives. Plant material was extracted using the Soxhlet method with solvents of varying polarity. Extracts were screened for phytochemicals and analyzed by GC–MS to identify major constituents. Larvicidal bioassays were conducted against fourth-instar larvae of Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus following WHO (2005) guidelines, and LC50 and LC90 values were determined via probit analysis. Key compounds were docked in silico against mosquito enzymes kynurenine aminotransferase (6MFB), acetylcholinesterase (6XYU), and glutathione S-transferase (2IMI), with Normal Mode Analysis evaluating complex stability. Phytochemical screening revealed alkaloids, flavonoids, phenols, and terpenoids, with ethanol and methanol extracts showing the richest profiles and strongest larvicidal activity. Ethanol extract achieved 100% mortality at 250 ppm, with LC50 values of 95.20 ppm (C. quinquefasciatus), 102.71 ppm (A. aegypti), and 112.83 ppm (A. stephensi). GC–MS identified 26 compounds, predominantly sterols, terpenoids, and fatty acids, with stigmasterol (22.22%) and γ-sitosterol (18.29%) as major constituents. Docking revealed strong binding of these sterols to 6MFB (−10.2 and −9.7 kcal/mol), exceeding temephos (−7.6 kcal/mol). NMA of the 6MFB–stigmasterol complex indicated low deformation energy (5.38 × 10−5) and adaptable hinge regions, supporting conformational stability. These findings demonstrate that C. gayana extracts exhibit potent larvicidal activity, underpinned by strong molecular interactions with mosquito enzymes, providing a promising basis for developing sustainable plant-based bioinsecticides and warranting further in vivo and field evaluations.