title: Tetranortriterpenoids from Cipadessa baccifera.
abstract: 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.
authors.affiliation: State Key Laboratory of Drug Research, Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 555 Zuchongzhi Road, Zhangjiang Hi-Tech Park, Shanghai 201203, People's Republic of China.
authors.forename: Li-She
authors.initials: LS
authors.lastname: Gan
authors.forename: Xiao-Ning
authors.initials: XN
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Wu
authors.forename: Jian-Min
authors.initials: JM
authors.lastname: Yue
mesh_terms: D004365:Drugs, Chinese Herbal / Q000737:chemistry* / Q000302:isolation & purification*; D036701:Limonins / Q000737:chemistry* / Q000302:isolation & purification*; D029582:Meliaceae / Q000737:chemistry*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010946:Plants, Medicinal / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D004365:Drugs, Chinese Herbal; D036701:Limonins