Activity of the compounds isolated from Blighia sapida (sapindaceae) stem bark against Aedes aegypti larvae
Blighia sapida (Sapindaceae) is commonly known as Ackee and in the South West Nigeria it is called Isin. The wood is resistant to termites and the pounded fruit and the stem bark is used as fish poison. The methanol extract of the stem bark reported to be active against the fourth instar larvae of Aedes aegypti was suspended in water and partitioned into n-hexane, dichloromethane and ethyl acetate. The most active n-hexane fraction with activity that was statistically insignificant to that of the methanolic extract gave LC50 , LC90 values of 1.81 ± 0.02, 3.17 ± 0.02 mg/mL at 24 h and 1.65 ± 0.05, 2.82 ± 0.35 mg/mL at 48 h. Endosulphan the positive control, had LC50 , LC90 values of 0.93 ± 0.06, 1.61 ± 0.12 mg/mL at 24 h and 0.90 ± 0.09, 1.44 ± 0.11 mg/mL at 48 h. The n-hexane fraction was subjected to chromatographic separations that led to the isolation of friedelin and α-amyrin. Friedelin and α-amyrin gave LC50LC90 0.07 ± 0.01, 0.13 ± 0.01 mg/mL and 0.05 ± 0.00, 0.08 ± 0.01 mg/mL respectively at 24 h and at 48 h there was 100% mortality. The activity of both compounds was statistically higher than that of Endosulphan.
Keywords: Blighia sapida, extract, chromatography, friedelin, α-amyrin, Aedes aegypti