Three new tetranortriterpenoids from neem seed oil.

Three new tetranortriterpenoids, 1alpha,2alpha-epoxy-17beta-hydroxyazadiradione (1), 1alpha,2alpha-epoxynimolicinol (2), and 7-deacetylnimolicinol (3), have been isolated from a methanol extract of neem oil (Azadirachta indica, seed oil) along with the known compounds epoxyazadiradione, 17beta-hydroxyazadiradione, gedunin, nimbin, and nimolicinol (4). Spectral studies and chemical transformations were used to establish the structure of compounds 1-3. The characterization of the epoxides 1 and 2 in neem oil is of biogenetic significance, as they may be considered as intermediates between A-ring enones and 1,3-diols among the A. indica tetranortriterpenoids.