title: Absolute structure determination of the highly biologically active bisdehydrodoisynolic acids.
abstract: In a project designed to relate the unexpected in vivo and in vitro properties exhibited by (+)- and (-)-bisdehydrodoisynolic acid with their absolute stereochemical structure, an X-ray crystal-structure analysis was undertaken of the highly estrogenic, poorly binding (-) enantiomer. (1) and (13)C NMR spectra are also reported for the first time. The crystal structure shows the cis juxtaposition of the carboxyl and ethyl groups, which are separated by a large torsion angle, and that only the carbon atom holding the carboxyl group is out of the plane in which the remainder of the fused three-ring moiety lies. The crystal structure, which unequivocally characterizes the (-) enantiomer as cis-13(S),14(R) and, implicitly, the (+) enantiomer as cis-13(R),14(S), will be useful in continued studies aimed at explaining the selective estrogen receptor modulation (SERM) of these enantiomers which, in some cases, produces significantly different end-organ effects compared to those of estradiol, in both males and females, affording the promise of a variety of therapeutic and pharmacologic applications.
authors.affiliation: Department of Chemistry and Biochemistry-4409, Southern Illinois University, Carbondale, Illinois 62901, USA. cal@chem.siu.edu
authors.forename: C Y
authors.initials: CY
authors.lastname: Meyers
authors.forename: Y
authors.initials: Y
authors.lastname: Hou
authors.forename: P D
authors.initials: PD
authors.lastname: Robinson
authors.forename: S
authors.initials: S
authors.lastname: Adler
authors.forename: W J
authors.initials: WJ
authors.lastname: Banz
authors.forename: T A
authors.initials: TA
authors.lastname: Winters
mesh_terms: D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010616:Phenanthrenes / Q000737:chemistry*
chemical_list: D010616:Phenanthrenes; C118032:bisdehydrodoisynolic acid