Spectroscopic and Biological Investigation of Nimbolide and 28-Deoxonimbolide from Azadirachta indica

Abstract
The reisolation of nimbolide [1] from Azadirachta indica of Tanzanian origin and the isolation and structure elucidation of a new limonoid, 28-deoxonimbolide [2], from the same plant source are reported. For the first time, unambiguous 1H- and 13C-nmr assignments of compounds 1 and 2 are presented, as well as their in vitro cytotoxic activity against human tumor cell lines.