Limonoids are phytochemicals of the triterpenoid class which are abundant in sweet or sour-scented citrus fruit and other plants of the families Cucurbitaceae, Rutaceae, and Meliaceae.[1] Certain limonoids are antifeedants such as azadirachtin from the neem tree.[2]
Chemically, the limonoids consist of variations of the furanolactone core structure. The prototypical structure consists of four six-membered rings and a furan ring. Limonoids are classed as tetranortriterpenes.
Citrus fruits contain the limonoids limonin, nomilin and nomilinic acid, while both neem seeds and leaves contain the limonoid azadirachtin, although higher concentrations are present in the former.
Eight previously unknown limonoids were identified via spectroscopy in the fruits of Chisocheton erythrocarpus gathered in Malaysia. These compounds were dubbed erythrocarpines after the species epithet. The same study tested several preparations of C. erythrocarpus extract as larvicidal agent against Aedes aegypti mosquitoes; they found that 1000 ppm of DCM extract resulted in 100% mortality of larva 24 hours after exposure.[3]