The bioactivity of four
flavonoid compounds, namely
poncirin,
rhoifolin,
naringin and
marmesin, from Poncirus trifoliata was studied against the Aedes aegypti. Larvicidal assays were conducted to evaluate the 24 h LC(50) and LC(90) values of the
flavonoid compounds. The lethal concentration (LC(50) and LC(90)) values ranged from 0.082 to 0.122 mg/l and 0.152 to 0.223 mg/l, respectively. The result of ovicidal test suggests that the ovicidal activity of the
flavonoid compounds was influenced by the concentration of
flavonoid compounds and age of the eggs. The result of oviposition test showed that the four
flavonoid compounds exhibited oviposition-deterrent activity against gravid female mosquitoes. Oviposition decreased with an increase in concentration of
flavonoid compounds. A laboratory test was carried out to evaluate protection period and percentage of repellency of four compounds diluted in
ethanol (10 mg/l). The compound
rhoifolin provided maximum 365.0 +/- 12.0 min protection and also 100.0% +/- 0.0 repellency against mosquito
bite followed by
poncirin,
marmesin and
naringin. None of the 25 volunteers of either sex exposed to 10% (w/v)
flavonoid compounds (4-h patch test) showed a positive skin
irritant reaction. All of the tested compounds proved to have various activities against different life stages of A. aegypti. Therefore,
flavonoid compounds from P. trifoliata can be a potential candidate for use in the development of commercial mosquitocidal products that may be an alternative to conventional synthetic chemicals, particularly in integrated vector control applications.