Abstract:
Background: Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus mosquitoes
are the major vectors for dengue fever, malaria, filariasis in Sri Lanka. The most of
mosquito repellents presently available in the market are mainly prepared with active
ingredients of synthetic origin and known to be harmful.
Objectives: Formulation of less toxic herbal cream and evaluation of in vitro mosquito
repellent activity against Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus.
Methodology: Oil in water emulsion based 10% w/w active ingredient cream was
formulated by using lemon grass essential oils and evaluated for physical stability
parameters (pH, odor, appearance, washability and colour) for 45 days at room temperature.
The repellent efficacy of the cream was tested by trained panel at medical research institute
in Sri lanka. Briefly, 1 g of herbal cream formulated was applied on the dosal hand area (25
cm2
) of the trained panel. The treated hand and untreated hand (negative control) were
exposed to 100 caged, blood starved, laboratory breeded female mosquitoes of three species
and repellency test was performed for 300 minutes after every 30 minutes.
Results and conclusions: The formulated cream was found to be homogenous, semi-solid,
washable and white color with pleasant odor and pH was in the range of 6 to 7. Total
protection without sitting or biting of all three species of mosquitoes was recorded to be 240
minutes for the formulated cream. A commercial herbal cream was tested as positive control
and its protection for mosquitoes sitting or biting was only 30 minutes. The results suggested
that the cream formulated with C. citrus essential oils has the potential mosquito repellent
activity and can be commercialized as a new, safe repellent product to prevent Aedes
aegypti, Anopheles stephensi and Culex quinquefasciatus bites.
