Studies in the chemical constituents of Azadirachta indica A. Juss (meliaceae). Part 10. Isolation and structure elucidation of isonimolicinolide, the first 17-acetoxy tetranortriterpenoid and nimolicinoic acid, the first hexanortriterpenoid with an apoeuphane (apotirucallane) skeleton

Abstract

Isonimolicinolide (1) and nimolicinoic acid (3), two new triterpenoids have been isolated from the neutral fraction of the fresh, undried, unruptured, ripe fruits of Azadirachta indica(neem) and their structures elucidated through chemical and spectral studies. The mother fraction of the two triterpenoids showed insect growth regulating properties against the pulse beetle (Callasobruchus analis). Isonimolicinolide (1) is the first example of a tetranortriterpenoid with an acetoxy function at C-17, and nimolicinoic acid (3) is the first instance of a hexanortriterpenoid with an apoeuphane (apotirucallane) skeleton as well as the first hexanortriterpenoidal acid, isolated from any source.