Objective: The main objective of the research work was to fabricate and characterize the thixogel formulations based on corn starch containing the combination of the essential oils from ylang-ylang (Cananga odorata Lamk.) and citronella (Cymbopogon nardus L.) plants. Then, we investigated their safety consideration, and mosquito repellent activities. Methods: Corn starch based thixogel was prepared by modified method of thixotropic emulsion. The thixotropic properties were measured by comparing the viscosity of the thixogels before and after shaking treatment on selected days during storage for 56 days. Study of skin irritation for thixogel application on human skin was conducted for three consecutive days with modified patch test method. Female Aedes aegypti mosquitoes (3-5 days old) were used in mosquito repellent studies. Results :The organoleptic studies showed that the formulations of thixogel without the essential oils (F0), ylang oils 2% (F1), citronella oils 2% (F2), and ylang oils 2% + citronella oils 2% (F3) were stable during storage for 56 days. In addition, the viscosity, and irritation skin studies confirmed that all formulas had a thixotropic properties, and without any irritation on human skin. Furthermore, the combination of ylang and citronella oils on corn starch-based thixogel (F3) significantly improved repellant activity against Aedes aegypti compared to its single essential oils on corn starch-based thixogel (F1 and F2). Conclusion: These results suggest that corn starch-based thixogel is promising technology for topical administration of the essential oils as repellent agents, which are safe for humans, domestic animals and friendly.
Key words: Aedes aegypti, Citronella, Essential oil, Thixogel, Mosquito repellent, Ylang-ylang.