Assessment of Mosquito Repellent Potentials of Ocimum gratissimum and Cymbopogon citratus Essential Oil and In silico Determination of Bioactive Compounds
Gabriel Nduka Enudinisu
*
Department of Medical Biochemistry, Delta State University, Abraka, Nigeria.
Victor Ngozi Enwemiwe
Department of Animal and Environmental Biology, Delta State University, Abraka, Nigeria.
Eric Esiwo
Department of Animal and Environmental Biology, Delta State University, Abraka, Nigeria.
Aghahowa Ehimwenma
Department of Animal and Environmental Biology, Delta State University, Abraka, Nigeria.
Chioma Cynthia Ojianwuna
Department of Animal and Environmental Biology, Delta State University, Abraka, Nigeria.
Acha Joy Onyewonuwa
Department of Medical Biochemistry, Delta State University, Abraka, Nigeria.
Innocent Onyesom
Department of Medical Biochemistry, Delta State University, Abraka, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Aims: To evaluate the repellency and in silico activities of bioactive compounds from Ocimum gratissimum and Cymbopogon citratus essential oils against Anopheles gambiae, and to determine their potential as eco-friendly alternatives to synthetic mosquito repellents.
Study Design: The laboratory-based experimental study involved integrating essential oil extraction, physicochemical characterization, repellency bioassays, and molecular docking analysis.
Place and Duration of Study: The research was carried out in the Department of Medical Biochemistry and Animal and Environmental Biology Department, Delta State University, Abraka, between May and July, 2025.
Methodology: Essential oils from O. gratissimum and C. citratus were extracted using the hydro-distillation method and incorporated into topical ointments at varying concentrations. Skin-friendliness was verified through physicochemical assessments including pH, viscosity, spreadability, and stability tests. Repellency assays followed WHO standard arm-in-cage protocols. In silico molecular docking was performed on major phytochemicals—particularly γ-Muurolene and Copaene—against An. gambiae glutathione S-transferases and odorant-binding proteins to assess binding affinities and potential mechanisms of repellency.
Results: Both essential oils demonstrated statistically significant repellency compared to untreated controls (p < 0.05). C. citratus showed stronger protection than O. gratissimum. The combined formulation produced the highest repellency, exceeding the efficacy of DEET at equivalent concentrations. Docking studies indicated strong binding affinities of γ-Muurolene and Copaene to GSTs and odorant-binding proteins, suggesting possible interference with mosquito detoxification pathways and host-seeking behavior.
Conclusion: Synergistic formulations of O. gratissimum and C. citratus essential oils show strong potential as sustainable, plant-based alternatives to synthetic repellents such as DEET. Further field trials in malaria-endemic regions are recommended to validate their safety, long-term stability, and real-world applicability for community-level malaria prevention.
Keywords: Malaria, repellency, Anopheles gambiae, molecular docking, Ocimum gratissimum and Cymbopogon citratus