Evaluation of Asparagus racemosus Root Extract and Eucalyptus Oil Formulations as Plant-Based Repellents Against Mosquitoes and Cockroaches

The increasing resistance of insects to synthetic repellents and the associated health and environmental concerns have prompted the search for safe and sustainable alternatives. The present study evaluated the insect-repellent potential of Asparagus racemosus root extract (EARR) formulated with eucalyptus oil against mosquitoes (Aedes aegypti) and cockroaches (Periplaneta americana). Roots were shade-dried, extracted with 70% ethanol, and subjected to phytochemical and GC-MS analysis, which revealed the presence of alkaloids, flavonoids, saponins, phenolics, and bioactive compounds including stigmasterol, flavone, n-hexadecanoic acid, asparanin B, and shatavarin I. The total phenolic and flavonoid contents were 5.419 mg GAE/g and 3.515 mg QE/g, respectively. Herbal cream and spray formulations incorporating EARR with eucalyptus oil exhibited satisfactory physicochemical parameters including pH, spreadability, viscosity, washability, clarity, and stability under accelerated conditions. In repellency bioassays, the EARR + eucalyptus cream achieved 81.32% protection against mosquitoes at 30 minutes, maintaining 33.11% repellency at 180 minutes, compared to 11.92% for eucalyptus alone. Similarly, the herbal spray demonstrated 77.89% repellency against cockroaches at 30 minutes and 27.04% at 180 minutes, significantly outperforming the control spray. Molecular docking further revealed strong binding affinities of stigmasterol (–11.6 kcal/mol) and asparanin B (–11.5 kcal/mol) with insect acetylcholinesterase, suggesting a potential neuroinhibitory mechanism underlying the observed repellency. The findings validate A. racemosus as a promising botanical source for eco-friendly, effective mosquito and cockroach repellent formulations, supporting its integration into sustainable pest management strategies.