title: Enzyme inhibition, radical scavenging, and spectroscopic studies of vanadium(IV)-hydrazide complexes.
abstract: Spectroscopic, enzyme-inhibition, and free-radical scavenging properties of a series of hydrazide ligands and their vanadium(IV) complexes have been investigated. Analytical and spectral data indicate the presence of a dimeric unit with two oxovanadium(IV) ions (VO(2+)) coordinated with two hydrazide ligands along with two water molecules. All complexes are stable in the solid state, but exhibit varying degrees of stability in solution. Binding of the coordinating solvent such as DMSO is indicated at the 6th position of vanadium in the dimeric unit followed by conversion to a monomeric intermediate species, [VOL(DMSO)3]1+ (L = hydrazide ligand). The free hydrazide ligands are inactive against snake venom phosphodiesterase I (SVPD), whereas oxovanadium(IV) complexes of these ligands show varying degrees of inhibition and are found to be non-competitive inhibitors. The superoxide and nitric oxide radical scavenging properties have been determined. Hydrazide ligands are inactive against these free radicals, whereas their V(IV) complexes show varying degrees of inhibition. Structure-activity relationship studies indicate that the electronic and/or steric factors that change the geometry of the complexes play an important role in their inhibitory potential against SVPD and free radicals.
authors.affiliation: Department of Chemistry, University of Karachi, Karachi-75270, Pakistan.
authors.forename: Uzma
authors.initials: U
authors.lastname: Ashiq
authors.forename: Rifat Ara
authors.initials: RA
authors.lastname: Jamal
authors.forename: Mohammad
authors.initials: M
authors.lastname: Mahroof-Tahir
authors.forename: Zahida T
authors.initials: ZT
authors.lastname: Maqsood
authors.forename: Khalid Mohammed
authors.initials: KM
authors.lastname: Khan
authors.forename: Iman
authors.initials: I
authors.lastname: Omer
authors.forename: Muhammad Iqbal
authors.initials: MI
authors.lastname: Choudhary
mesh_terms: D002412:Cations; D019281:Dimerization; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000737:chemistry* / Q000494:pharmacology*; D006834:Hydrazines / Q000737:chemistry*; D008024:Ligands; D009569:Nitric Oxide / Q000737:chemistry / Q000494:pharmacology; D009942:Organometallic Compounds / Q000737:chemistry* / Q000494:pharmacology; D043264:Phosphodiesterase I / Q000037:antagonists & inhibitors; D013057:Spectrum Analysis; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013481:Superoxides / Q000737:chemistry / Q000494:pharmacology; D014638:Vanadates / Q000737:chemistry; D014639:Vanadium / Q000737:chemistry*
chemical_list: D002412:Cations; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D006834:Hydrazines; D008024:Ligands; D009942:Organometallic Compounds; D014639:Vanadium; D013481:Superoxides; C075743:oxovanadium IV; C029424:hydrazine; D009569:Nitric Oxide; D014638:Vanadates; D043264:Phosphodiesterase I; C470790:phosphodiesterase I, snake venom; D004121:Dimethyl Sulfoxide