Mosquito Repellent Activity and Phytochemical Characterization of Essential Oils From Striga hermonthica, Hyptis spicigera and Ocimum basilicum Leaf Extracts

摘要

The main aim of this study is to screen the phytochemicals and compare the mosquito repellent activities of essential oils from Hyptis spicigera, Striga hermonthica and Ocimum basilicum (Basil) against Anopheles gambiae and Culex quinquefasciatus under laboratory conditions. The global threat of malaria to human race and the need to control its advances is on the focus. Mosquito is the target being the primary host in the spread of malaria. Alkaloids, saponnins, steroids, tannins and terpenoids were present in all the 3 oils. Cardiac glycosides were detected in both H. spicigera and Striga hermonthica, while anthraquinone and phlobatin were present in Striga hermonthica and Hyptis spicigera, respectively. The FTIR spectrum revealed the presence of C = O, C-l, C-O-C, OH, C-N, S = O and NO₂. These correlate with the functional groups in the identified phytochemicals. At 50% concentration, O. basilicum and Hyptis spicigera oil exhibited higher repellant potential on Anopheles gambiae with protection time of 183 and 120 min, respectively, while H. spicigera and S. hermonthica had protection time of 180 and 175 min, respectively against Anopheles gambiae. At 100% concentration, O. basilicum oil exhibited the highest protection time against the two species of mosquito tested and at all the concentrations. O. basilicum was equally potent against Culex quinquefasciatus with 180 min protection time. S. hermonthica had more repellent potential against Culex quinquefasciatus. The essential oils of Striga hermontica, Ocimum basilicum and Hyptis spicigera leaf extracts have been confirmed to have potentials as mosquito repellent agents against Anopheles gambiae and Culex quinquefasciatus.