My Times Today.Neem is known for its medicinal and insecticidal properties for centuries. It is chemicals referred to as limonoids that give neem these properties. Indian scientists have now figured out the process of limonoid production in neem.Neem is a storehouse of useful chemicals, the most important being Azadirachtin A, which is well known natural insecticide. It belongs to a class of chemicals known as tetranor-triterpenoids or limonoids. Over 150 limonoids have been isolated and characterized from different parts of neem tree so far, but the process of their production had so far remained unknown.Limonoids possess very complex chemical structure in which isoprene units serve as building blocks. In higher plants, biosynthesis of isoprenes occurs through either of the two biosynthetic pathways – mevalonate pathway (MVA) or the methyl-erythritol phosphate pathway (MEP) or a combination of both.Researchers grew neem cells in an artificial growth medium supplemented with different glucose isotopes. The growing cells utilized these labelled glucose isotopes for synthesis of limonoid. For further confirmation, same studies were carried out in presence of MVA and MEP pathway specific chemical inhibitor. MVA pathway specific inhibitor – mevinolin – drastically affected the growth and limonoid content, while MEP pathway inhibitor didn’t interfere with biosynthesis of limonoids.