Abstract:
In the tropics, malaria has become the most alarming public health problem, hence the need for a mosquito repellent, a personal protection against the vector. The concern about the deleterious effects associated with synthetic chemicals like N, N-diethy-3-methylbenzamide (DEET) has elicited the interest to explore plant materials as source of natural repellent for mosquito control. The aim of this study was to formulate and evaluate herbal mosquito repellent cream based on solid lipid microparticles (SLM). To determine the mosquito repellent activity of Ocimum gratissimum ethanol extract and eucalyptus oil, SLM-based creams containing various concentrations of Ocimum gratissimum and eucalyptus oil were formulated and tested against three species of mosquito viz; Anopheles gambaiae, Aedes aegypti and Culex quinquefasciatus. The SLM-based cream formulations were characterized for their physicochemical (colour, texture, odour and stability) and rheological properties (spreadability, oclusivity), particle size and pH. It was found that the repellent effect of the creams was dependent on the concentration of the repellents. Also, the creams with Ocimum gratissimum ethanol extract provided protection for up to two hours against Anopheles gambaiae and Culex quinquefasciatus, while the creams with eucalyptus oil provided protection for up to two hours against Anopheles gambaiae only.
On physical examination, the products were ‘cream’ coloured, smooth and aromatic for the eucalyptus oil creams, and light green, smooth and of a characteristic odour for Ocimum gratissimum extract creams. The mean value ± SD for the rheological properties of the creams were, particle size; F = 10.40; p < 0.1, spreadability; F = 0.32; p > 0.05, occlusivity; F = 11.81; p < 0.01 and pH; F = 2.89; p > 0.05.
