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Title of Thesis

Rifat Ara Jamal
Institute/University/Department Details
Departmental of Chemistry/ University of Karachi
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
quadravalent oxovanadium, aroylhydrazine, vanadium, ligands, urease, phosphodiesterases, alpha glucosidases

Vanadium is known to exhibit several bioactivities and shows its potential for its use as a pharmaceutical drug. Much of the research is underway in exploring bioactivities of vanadium complexes and understanding the mechanism of its biological properties. In an effort to uncover the chemistry and biochemistry of potential bioactive vanadium compounds, the synthesis and characterization of the oxovanadium(IV) complexes of aroylhydrazine ligands with systematic variation of electronic and steric factors is reported here. Enzyme inhibition studies with urease, phosphodiesterase and alpha-glucosidase along with leishmanicidal activity, immunomodulatory activity and radical scavenging properties of these complexes are determined to explore the structure function relationship.

Twelve aroylhydrazine ligands with systematic variation of susbtitutents and their vanadium(IV) complexes are synthesized and characterized by using different spectroscopic techniques. Physical, magnetic and spectral data supports the presence of a dimeric structure in which each vanadium is coordinated with four coordinating atoms of two aroylhydrazine ligands and an oxygen atom of water molecule. IR spectra support the coordination of aroylhydrazine ligands through carbonyl oxygen and amine nitrogen. Vanadium-aroylhydrazine complexes exhibit the subnormal values of magnetic moments suggesting the dimeric nature of complexes. Similar values of magnetic moment, conductivity and spectral characteristics of different complexes may indicate existence of similar structure of the complexes.

UV -vis spectra support the square pyramidal coordination of vanadium centers. The stability of different complexes in solution of coordinating solvent DMSO (dimethylsulpxide) is very different over time. These studies indicate binding of DMSO molecule at sixth position of both vanadium centers keeping the dimeric structure intact. Over time these species are converted to monomeric specie in which both solvent molecule and aroylhydrazine ligands are coordinated with the vanadium centre.

Most of the ligands are inactive against urease, phosphodiesterases and alpha glucosidases, whereas, after coordination with vanadium they show very promising inhibitory potential against these enzymes. Al complexes exhibit non-competitive inhibition against all the enzymes. 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 and superoxide free radical. Leishmanicidal activity studies show varying degree of activities for aroylhydrazine and their vanadium(IV)-aroylhydrazine 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 enzyme inhibitory potential, radical scavenging activity and phytotoxicity.

Oxovanadium(N) complexes of aroylhydrazine were screened for their immunomodulatory activity using normal and cancer cell lines. The cell lines used in these studies include normal fibroblast 3T3, beside the Prostate cancer (PC-3), cervical cancer Hela and C33A cell lines. Compounds found significantly active, but non-toxic in our systems could be used as immunosuppressive or anti-inflammatory agents. However, the exact mechanism and the nature of their immunomodulatory activity need to be further investigated.

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3934.29 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
266.31 KB
2 1 Introduction 1
403.89 KB
  1.1 Aqueous Oxovanadium Chemistry 3
  1.2 Chemistry Of Vanadyl ( Vo 2+ ) Ion 4
  1.3 References 12
3 2 Experimental 18
273.93 KB
  2.1 Materials 19
  2.2 Physical Measurements 19
  2.3 Synthesis 22
  2.4 References 31
4 3 Results And Discussion 33
845.46 KB
  3.1 Synthesis 33
  3.2 Characterization Of Oxovanadium (IV) Complexes Of Aroylhy 35
  3.3 Conclusion 59
  3.4 References 60
5 4 Urease Inhibition And Phytotoxic Studies Of Oxovanadium (IV) Complexes Of Aroylhydrazine 62
470.96 KB
  4.1 Enzyme Inhibition Studies With Urease 63
  4.2 Urease 64
  4.3 Phytotoxicity 71
  4.4 References 76
6 5 Insulin-Like Activity Of The Oxovandium ( IV) Complexes Of Aroylhydrazine 80
583.98 KB
  5.1 ‘-Glucosidases 90
  5.2 References
7 6 Radical Scavenging Properties Of Oxovanadium ( Iv) Complexes Of Aroylhydrazine 104
458.42 KB
  6.1 Reactive Oxygen Speices ( Ros ) 105
  6.2 Antioxidants 107
  6.3 Experimental 111
  6.4 References 119
8 7 Lieshmanicidal Studies Of Oxavanadium (IV) Complexes Of Aroylhydrazine 122
268.91 KB
  7.1 Lishmaniasis 123
  7.2 References 129
9 8 Immunomodulatoty And Anticancer Studies Of Oxovanadium ( IV) Complexes Of Aryolhydrazine 132
397.63 KB
  8.1 The Immunological And Anticancer Studies 133
  8.2 Phagocytes 134
  8.3 Methods For Detection Of Immunomodulating Compounds 135
  8.4 Immunosuppression 136
  8.5 Anticancer And Immunomodulatory Activities Of Vanadium Compounds 136
  8.6 Anticancer Activity Need 138
  8.7 Immunomodulatory Importance 138
  8.8 Experimental 140
  8.9 Results And Discussion 141
10 9 References 147
168.9 KB