Asian Journal of Applied Chemistry Research

The increasing health and environmental concerns associated with synthetic mosquito repellents have necessitated the development of safer, plant-based alternatives. This study produced and evaluated mosquito repellent creams formulated from lemon grass (Cymbopogon citratus), clove (Syzygium aromaticum), and neem (Azadirachta indica) extracts, including their combinations. Fixed oils were extracted using n-hexane and incorporated into seven oil-in-water cream formulations. Physicochemical properties, chemical composition (GC-MS), antimicrobial activity (agar well diffusion against Salmonella sp., Escherichia coli, Candida albicans, and Aspergillus sp.) were determined. Repellency efficacy (modified Arm-in-Cage method) was evaluated using anopheles mosquito (Anopheles gambiae). The experiments were performed in triplicates. Statistical analysis of the results was done by one –way analysis of variance (ANOVA) and post hoc test. GC-MS revealed that lemon grass extraction with n-hexane altered its composition, yielding mainly 9-Octadecenoic acid (42.52%) instead of volatile citral, reducing its repellency. Significant difference was observed in the density, refractive index and viscosities of the extracted oils. There was significant difference in the oxidative properties of the extracted oils except in thiobarbituric acid (TBA) levels. ANOVA revealed distinct concentration – dependent behaviors for Salmonella sp., Candida albicans, and Aspergillus sp., whereas E. coli showed no statistically significant sensitivity to concentration variance. The extracted oils provided better antioxidant, antimicrobial and mosquito repellent efficiency while standing alone. Formulations combining the extracts yielded antagonistic rather than synergistic effects in most cases.