SYNTHESIS AND CHARACTERIZATION OF THE COMPLEXES OF VANADIUM WITH HYDRAZIDE: POTENTIAL ANTIDIABETIC AGENT

Uzma, Muhammad Ashiq (2006) SYNTHESIS AND CHARACTERIZATION OF THE COMPLEXES OF VANADIUM WITH HYDRAZIDE: POTENTIAL ANTIDIABETIC AGENT. Doctoral thesis, University of Karachi.

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Abstract

Vanadium plays an important role in biological systems and exhibits variety of bioactivities. In an effort to uncover the chemistry and biochemistry of vanadium with nitrogen and oxygen containing ligands, Synthesis, characterization, enzyme inhibition. microbial and antioxidant studies of vanadium(IV) complexes with hydrazide ligands is reported here. Substituents on these ligands exhibit systematic variations of electronic and steric factors. Elemental and spectral data indicates the presence of a dimeric unit with two vanadium(IV) ions coordinated with two hydrazide ligands along with two water molecules. The magnetic properties support the dimeric nature of the complexes in solid state. The magnetic moments are in the range of 1.10 to 1.54 B.M. which are lower than that exhibited by one unpaired electron of V(IV) complexes. Similar magnetic moments of different complexes may indicate existence of similar structures of the complexes. The complexes exhibit molar conductivity in DMSO in the range of 32.20 to 148.30 ohm-1 cm2 mol-1 It falls into the range of 1:1 ionic ratio suggesting non coordination of the sulfate ion and supports the formation of outer-sphere complex. The stability studies of these complexes over time in coordinating solvent, DMSO, indicates binding of the solvent molecules to give [V2O2L2(H2O)2(DMSO)2]2+ (L = hydrazide ligand) and then conversion of it to a monomeric intermediate species, [VOL(DMSO)3]1+. All complexes are stable for at least twelve hours whereas, after that different complexes exhibit very different behavior. Most of the ligands are inactive against snake venom phosphodiesterase I (SVPDE). urease. α-glucosidase and thymidine phosphorylase. whereas, after coordination with vanadium they show very promising inhibitory potential against these enzymes and were found to be non-competitive inhibitors. To understand the role of these complexes towards free radicals which play important role in several diseases including diabetes and its complications, we studied free radical scavenging properties of these complexes against DPPH, superoxide and nitric oxide free radical. The ligands are inactive in case of superoxide and nitric oxide whereas active against DPPH radical, however, the complexes show promising inhibitory activity for all free radicals. These complexes also show low phytotoxicity. Bactericidal, leishmanicidal, fungicidal microbial activities shows varying degree of activities for hydrazides and their complexes. Structure activity relationship studies indicate that the steric and/or electronic effects that may change the geometry of the complexes play an important role in their inhibitory potential, radical scavenging activity and phytotoxicity.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: vanadium, hydrazide, antidiabetic agent, ligands, aqueous oxovanadium, leishmaniasis, fungal infections, ureases, phosphodiesterases, α-glucosidases, thymidine phosphorylase
Subjects: Q Science > QD Chemistry
Depositing User: Muhammad Khan Khan
Date Deposited: 05 Sep 2016 07:27
Last Modified: 05 Sep 2016 07:27
URI: http://eprints.hec.gov.pk/id/eprint/925

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