Tetranortriterpenoids from Cipadessa baccifera

• DOI: 10.1021/np070229t
• Publication Date: 2007-07-04T11:00:59Z
• Authors: Li-She Gan; Xiao-Ning Wang; Yan Wu; Jian-Min Yue
• Keywords: Limonins; Plants, Medicinal; Molecular Structure; Seeds; Stereoisomerism; Meliaceae; Nuclear Magnetic Resonance, Biomolecular; 01 natural sciences; Drugs, Chinese Herbal; 0104 chemical sciences

Five new mexicanolide-type tetranortriterpenoids, tigloylseneganolide A (1), 2'R-methylbutanoylproceranolide (2), 2'S-methylbutanoylproceranolide (3), 2'R-cipadesin A (4), and 2'R-cipadesin (6), as well as the known 2'S-epimers of 4 and 6 (5 and 7), together with six other known limonoids, were isolated from the seeds of Cipadessa baccifera. The structures of these compounds were elucidated on the basis of spectroscopic analyses and chemical methods. 1H NMR-based conformational analysis was applied to establish the absolute configuration of the sterically hindered 2-methylbutanoyl in three epimeric pairs (2-7). A general rule for the determination of the absolute configurations of 2R- and 2S-methylbutanoyl groups at C-3 of a limonoid in a mixture is proposed.