A new tetranortriterpenoid, meliatetraolenone [24,25,26,27-tetranor-apotirucalla-(apoeupha)-6α-O-methyl, 7α-senecioyl(7-deacetyl)-11α,12α,21,23-tetrahydroxy-21,23-epoxy-2,14,20(22)-trien-1,16-dione] (1) was isolated from the methanolic extract of fresh leaves of Azadirachta indica along with the known compound odoratone (3) which was hitherto unreported from this source. Their structures have been elucidated by spectral studies including 2D NMR. The insecticidal activities of 1 as well as those of odoratone (3) are reported. 1 and odoratone both showed mortality on fourth instar larvae of mosquitoes (Anopheles stephensi) with LC50 values of 16 and 154 ppm, respectively.
2003 The Pharmaceutical Society of Japan