Biologically Active Triterpenoids of Biogenetic Interest from the Fresh Fruit Coats of Azadirachta indica

Two new triterpenoids of biogenetic interest, namely, 26,27-dinor-17-oxa-1, 14,20(22)-trien-3, 16-dioxo-7α-acetoxy-17β-methoxy-4,4,8-trimethyl(5α, 13α)-cholane (meliacinin) 1 and 24,25,26,27-tetranor-apotirucalla(-apoeupha)-7α-acetoxy-1,14,20(22)-trien-3-oxo-23-oic acid (azadironic acid) 2 have been isolated from the fresh fruit coats of Azadirachta indica. Their structures were established through comparative spectral studies. 1 is the first dinorapoeuphane with seco ring D of deoxygedunin type and 2 is the first tetranorapoeuphane with an open side chain representing a biogenetic intermediate between the intact triterpenoids and meliacins. Both 1 and 2 showed toxicity against mosquito (Anopheles stephensi) with LC50 13 and 4.5 ppm, respectively.