title: Structural and functional characterization of seven spermicidal vanadium(IV) complexes: potentiation of activity by methyl substitution on the cyclopentadienyl rings.
abstract: In a systematic effort to identify and develop effective vanadocene(IV) complexes as a new class of contraceptive agents, the effect of methyl substitution in the cyclopentadienyl rings of Cpx2VCl2 on their spermicidal activity has been examined. The spermicidal activities of compounds Cpx2VCl2 [Cpx = Me5Cp (Cp*) (1), Cp (3), MeCp (Cp') (5)], as well as two of their corresponding vanadium(V) oxidation products Cp*V(O)Cl2 (2) and CpV(O)Cl2 (4), were examined by computer-assisted sperm analysis (CASA). These analyses have established that penta-substitution of the Cp ring by electron-donating methyl groups augments the spermicidal activity 10-fold. The corresponding V(V) oxo compounds, Cp*V(O)Cl2 (2) and CpV(O)Cl2 (4), tested under identical conditions did not show as effective spermicidal activity even though these complexes have a pseudo-tetrahedral geometry similar to the active vanadocene(IV) dichlorides. Two pseudo-octahedral V(IV) complexes with tris-pyrazolyl borate as ligand, (HBpz3)V(O)Cl.DMF (6) and (HB(3,5-Me2pz)3)V(O)Cl.DMF (7), were also found to exhibit potent spermicidal activity. Although some vanadium(IV) complexes may immobilize sperm due to the generation of .OH radicals, the lack of spermicidal activity of VOSO4 which generates .OH radicals, and the potent spermicidal activity of [Cp2V(acac)][O3SCF3] (8), and [Cp2V(DeDtc)][O3SCF3] (9) which do not generate .OH radicals, indicate that .OH radical mediated reactions may not be essential for the spermicidal activity of vanadium(IV) complexes.
authors.affiliation: Department of Chemistry, Hughes Institute, St. Paul, MN 55113, USA.
authors.forename: P
authors.initials: P
authors.lastname: Ghosh
authors.forename: O J
authors.initials: OJ
authors.lastname: D'Cruz
authors.forename: D D
authors.initials: DD
authors.lastname: DuMez
authors.forename: J
authors.initials: J
authors.lastname: Peitersen
authors.forename: F M
authors.initials: FM
authors.lastname: Uckun
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D008297:Male; D008432:Mathematical Computing; D017711:Nonlinear Dynamics; D012044:Regression Analysis; D013081:Sperm Motility / Q000187:drug effects; D013089:Spermatocidal Agents / Q000737:chemistry* / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D017968:Vanadium Compounds / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D013089:Spermatocidal Agents; D017968:Vanadium Compounds; D017665:Hydroxyl Radical; C030754:vanadocene dichloride; D006861:Hydrogen Peroxide