title: Khayanolides from African mahogany Khaya senegalensis (Meliaceae): A revision.
abstract: Five khayanolides (1-O-acetylkhayanolide B 1, khayanolide B 2, khayanolide E 3, 1-O-deacetylkhayanolide E 4, 6-dehydroxylkhayanolide E 5) were isolated from the stem bark of African mahogany Khaya senegalensis (Meliaceae). Their structures and absolute configurations were determined through extensive spectroscopic analyses including MS, NMR, and single-crystal X-ray diffraction experiments. The results established that two previously reported khayanolides, 1alpha-acetoxy-2beta,3alpha,6,8alpha,14beta-pentahydroxy-[4.2.1(10,30).1(1,4)]-tricyclomeliac-7-oate 6 and 1alpha,2beta,3alpha,6,8alpha,14beta-hexahydroxy-[4.2.1(10,30).1(1,4)]-tricyclomeliac-7-oate 7, were, in fact, 1-O-acetylkhayanolide B 1 and khayanolide B 2, and that the two reported phragmalin derivatives, methyl 1alpha-acetoxy-6,8alpha,14beta,30beta-tetrahydroxy-3-oxo-[3.3.1(10,2).1(1,4)]-tricyclomeliac-7-oate 8 and methyl 1alpha,6,8alpha,14beta,30beta-pentahydroxy-3-oxo-[3.3.1(10,2).1(1,4)]-tricyclomeliac-7-oate 9, were, in fact, khayanolide E 3 and 1-O-deacetylkhayanolide E 4, respectively. Based on the results from this study and consideration of the biogenetic pathway, the methyl 6-hydroxyangolensate in African mahogany K. senegalensis should have a C-6 S configuration while methyl 6-hydroxyangolensate in genuine mahogany Swietenia species should have a C-6 R configuration.
authors.affiliation: Department of Food Science and Human Nutrition, Clemson University, Clemson, 29634 SC, USA.
authors.forename: Huaping
authors.initials: H
authors.lastname: Zhang
authors.forename: Junjie
authors.initials: J
authors.lastname: Tan
authors.forename: Don
authors.initials: D
authors.lastname: Vanderveer
authors.forename: Xi
authors.initials: X
authors.lastname: Wang
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wargovich
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
mesh_terms: D000349:Africa; D018360:Crystallography, X-Ray; D005663:Furans / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D029582:Meliaceae / Q000737:chemistry*; D015394:Molecular Structure
chemical_list: D005663:Furans