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Synthesis, characterisation and insulin-mimetic activity of oxovanadium(IV) complexes with amidrazone derivatives

Cocco, Maria Teresa and Onnis, Valentina and Ponticelli, Gustavo and Meier, Beate and Rehder, Dieter and Garribba, Eugenio and Micera, Giovanni (2007) Synthesis, characterisation and insulin-mimetic activity of oxovanadium(IV) complexes with amidrazone derivatives. Journal of Inorganic Biochemistry, Vol. 101 (1), p. 19-29. ISSN 0162-0134. Article.

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DOI: 10.1016/j.jinorgbio.2006.07.015

Abstract

The complexation of VO2+ ion by ten acetamidrazone and 2-phenylacetamidrazone derivatives (L) was studied. Sixteen novel VO2+ complexes were synthesised and characterised through the combined application of analytical and spectroscopic (EPR (electron paramagnetic resonance), FT-IR and diffuse reflectance electronic absorption) techniques. Eight are 1:2 species of composition [VOL2]SO4 · xH2O and eight are 1:1 species with formula [VOL(SO4)]n · xH2O. The experimental data suggest a bidentate coordination mode for L with the donor set formed by the imine nitrogen and the carbonyl oxygen. EPR spectra indicate a square-pyramidal geometry for the 1:1 complexes and a penta-coordinated geometry intermediate between the square-pyramid and the trigonal-bipyramid for the 1:2 species. The hyperfine coupling constant along z axis, Az, of the 1:2 complexes exhibits a marked reduction with respect to the predicted value (~148 × 10−4 cm−1 vs. ~170 × 10−4 cm−1). IR spectroscopic evidence supports the presence of sulphate as a counter-ion in the 1:2, and as a bridging bidentate ligand in the 1:1 complexes. Insulin-mimetic tests on modified fibroblasts, based on a modified MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazoliumbromide) assay, performed on three of the bis-chelated and eight of the mono-chelated derivatives, indicate that they are biologically active. The similar hydro/lipophilicity and the lack of ligand substituents recognizable by cell membrane receptors prevent substantial differentiation in the insulin-mimetic action.

Item Type:Article
ID Code:1465
Status:Published
Refereed:Yes
Uncontrolled Keywords:Oxovanadium(IV) complexes, amidrazone ligands, spectroscopic characterisation, insulin-mimetic activity
Subjects:Area 03 - Scienze chimiche > CHIM/03 Chimica generale e inorganica
Divisions:001 Università di Sassari > 01 Dipartimenti > Chimica
Publisher:Elsevier
ISSN:0162-0134
Copyright Holders:© 2006 Elsevier
Additional Information:Pubblicato online il 5 agosto 2006.
Deposited On:18 Aug 2009 10:05

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