PHYTOCHEMICAL STUDY AND LARVICIDAL ACTIVITY OF THREE EXTRACTS FROM CASSIA SIEBERIANA BARK

Malaria, caused by protozoa of the genus Plasmodium, is endemic in sub-Saharan Africa, and vector control remains the main intervention for reducing its transmission. Synthetic insecticides, although very effective against exposed mosquitoes, cause environmental problems, which motivates the search for plant-based alternatives. In this study, three extracts (cyclohexane, chloroform and methanol) were prepared by maceration from the bark of Cassia sieberiana, screened phytochemically and tested at four doses (50 to 6.25 mg/mL) on third-stage larvae of Anopheles gambiae. The extraction yield was highest with methanol (17.42%), against about 1% with cyclohexane and chloroform. Phytochemical screening showed that the methanolic extract was rich in polyphenols, flavonoids and tannins, whereas alkaloids were absent from all extracts. Mean larval mortality was just under 70% and increased with both dose and exposure time. The methanolic extract was the most active, with 85% mortality after 48 h of exposure, an activity that may be related to its high polyphenol content. Analysis of variance showed significant effects of extract, dose and exposure time (P < 0.05). These results suggest that C. sieberiana bark is a potential source of bioinsecticides against malaria vectors.