The azadirachtin content of neem cake fractions and its bioactivity against Spodoptera litura

Neem cake is a by-product of the neem seed extraction process, which exhibits insecticidal properties. Azadirachtin is the main component of neem oil and is known as an anti-insecticide compound against more than 200 species of insect pests. This work reports the azadirachtin content of the neem cake fraction and its bioactivity against Spodoptera litura. Neem cake was extracted with methanol, then fractionated using n-hexane, and ethyl acetate. The antifeedant activity of the fractions was evaluated using the 4th instar of S. litura larvae. The bioassay was conducted using the choice leaf disc test with 2.5; 5; and 10 % (v/v) concentrations of each fraction. The Azadirachtin content of each fraction was analyzed using High-Performance Liquid Chromatography. In the phytochemical test, the n-hexane fraction contained triterpenoids and saponins. The ethyl acetate fraction contains alkaloids, flavonoids, saponins, triterpenoids, and tannins. The residual fraction contains alkaloids, flavonoids, saponins, steroids, and tannins. HPLC analysis showed that the ethyl acetate fraction had the highest azadirachtin content (132.684 ppm) while the n-hexane fraction was 20.299 ppm. The highest bioactivity was obtained in the residual fraction (100%) at a concentration of 2.5%. The antifeedant activity was influenced by non-azadiractin compounds in the residual fraction which requires further analysis.