2-[3-Hexadecanoyloxypropoxy(hydroxy)phosphoryl]oxyethyl-trimethylazanium, commonly known as Desacetylazadirachtin or Deacetylazadirachtin, is a major active metabolite of azadirachtin, a well-known botanical insecticide derived from the neem tree (*Azadirachta indica*). It is a complex tetranortriterpenoid limonoid compound. This compound is a potent insect growth regulator (IGR) and feeding deterrent. It acts primarily by disrupting the endocrine system of insects, particularly by interfering with the synthesis and release of molting hormones (ecdysteroids), leading to incomplete molting, developmental abnormalities, and eventual death. It also exhibits antifeedant properties, deterring pests from consuming treated plants. Its application is primarily in organic and integrated pest management (IPM) programs for controlling a wide range of agricultural pests, including caterpillars, beetles, and aphids, while being relatively non-toxic to beneficial insects, mammals, and birds. Desacetylazadirachtin is considered a key bioactive component contributing to the overall efficacy of commercial neem-based insecticidal formulations. Its mode of action, targeting specific insect physiology, makes it a valuable tool for managing insecticide resistance.