In vitro insecticidal activity on Anopheles gambiae giles, 1902 and antiplasmodial activity on Plasmodium falciparum welch, 1897 of essential oils of some plants of the Cameroonian flora

Abstract

For decades, pest control has been confronted with the double resistance of vectors to usual insecticides and of parasites to conventional molecules. The search for new natural molecules is therefore a necessity. The present study aimed to evaluate the insecticidal and anti-plasmodial potential of essential oils from the leaves of 10 species of plants belonging to the Myrtaceae family (Syzygium aromaticum, Psidium littorale, Eucalyptus globulus, Eugenia uniflora and Callistemon rigidus), Verbenaceae (Lippia adoensis and Lantana camara) and Cupressaceae (Cupressus sempervirens, Cupressus macrocarpa and Cupressus lusitanica). The essential oils were extracted by steam distillation using a Clevenger-type apparatus. Their chemical composition was determined by GC-MS. Insecticidal tests were performed according to the WHO protocol and the in vitro anti-plasmodial activity of these essential oils was evaluated by the radioisotope method. Except for S. aromaticum and E. uniflora, the essential oils of the plants studied yielded higher content in monoterpenes (49.01% to 100%) than in sesquiterpenes (0% to 49.82%). At 50 ppm, laboratory adults of A. gambiae (tkd95 = 10.32mn) and those of A. gambiae s.l. (tkd95=7.9 min) were more sensitive to the essential oils of S. aromaticum and L. adoensis respectively. Mature larvae of A. gambiae S.l. (LC95=35.4 ppm) and laboratory larvae of A. gambiae (LC95=35.4ppm) were more sensitive to E. uniflora oil. In addition, the essential oils studied had shown in vitro antiplasmodial activity against Plasmodium falciparum. E. globulus (IC50 = 12.13 ppm) and L. camara (IC50 = 12.34 ppm) appeared to be the most active. These oils can be used as a basis for the development of new biocides and natural antimalarials.