Larvicidal and Brine Shrimp Activities of Vitex Schiliebenii Extracts and Isolated Phytoecdysteroids on Anopheles gambiae Giles S.S Larvae

Abstract

Acetone, methanol and aqueous extracts of the leaves, stem bark and root bark of Vitex schiliebenii belonging to the family Verbenaceae were evaluated for their larvicidal activity against late 3rd/early 4th Anopheles gambiae Giles s.s. larvae (Diptera: Culicidae). The extracts of the acetone leaves and stem bark were active with LC50 values of 14.6 and 17.4 ppm respectively at 24 hrs. These extracts exhibited low toxicity to brine shrimps with LC50 values of 180.9 and 154.4 ppm respectively. The constituents in these extracts were isolated and evaluated and the phytoecdysteroids 20-hydroxyecdysone (1) and stigmasterol (2) were identified as the active principles in the acetone stem bark while γ-sitosterol (3) was the active principle of the acetone leaf extract. The methanol leaf extract, the stem bark aqueous extract and the acetone root bark also showed potency against the mosquito species.