Azadirachtin A is a chemical compound belonging to the limonoids. It is a secondary metabolite present in the Neem tree seeds. The molecular formula is C₃₅H₄₄O₁₆. Azadirachtin A is a highly oxidised tetranortriterpenoid which boasts a plethora of oxygen functionality, comprising an enol ether, acetal, hemiacetal, and tetra-substituted oxirane as well as a variety of carboxylic esters. It is classified among the plant secondary metabolites

Structure of Azadirachtin A

Additionally, both secondary and tertiary hydroxyl groups and tetrahydrofuran ether are present. Inspection of the molecular structure reveals 16 stereogenic centres, 7 of which are quaternary. These characteristics explain the great difficulty encountered when trying to produce it by a synthetic approach. It was initially found to be active as a feeding inhibitor towards the desert locust (Schistocerca gregaria), it is now known to affect over 200 species of insect, by acting mainly as an antifeedant and growth disruptor . It fulfils many of the criteria needed for a natural insecticide if it is to replace synthetic compounds. Azadirachtin A is biodegradable and shows very low toxicity to mammals, thus being environmentally sound.

This compound is found within the seeds of the Neem tree (0.2 to 0.8 percent by weight). Many more compounds, related to Azadirachtin A, are present in the seeds as well as in the leaves and the bark of the Neem tree which also show strong biological activities.