Ring A-seco mosquito larvicidal limonoids from Turraea wakefieldii.

Abstract Five novel limonoids, 1 – 5 , were isolated from the root bark of Turraea wakefieldii and were characterized as tecleaninoid derivatives. This is the first report of the natural occurrence of tecleanin-type limonoids with a five-membered-ring A-seco structure for which we propose the name neotecleanins. The relative stereochemical structures of compounds 1 – 5 were established on the basis of NMR spectroscopy. The absolute stereochemical structure of 5 was confirmed by X-ray diffraction methods. In mosquito larvicidal assays, compounds 1 , 2 and 4 showed dose-dependent larvicidal activity against larvae of Anopheles gambiae s.s .