New zinc(II) complexes with tetradentate amino acid derivatives:structure characterization,solution chemistry,and in vitro insulinomimetic activity

摘要

Twelve new amino acid derivatives /Zn(II) complexes were prepared by the reactions of ZnSO_4 and nine tetradentate ligands,Gly,Ala,Val,Leu,Ser and His derivatives and three pentadentate ligands,Asp and His derivatives.The X-ray structure analysis of [Zn_3(N-pyridylmethyl-His)_3(H_2O)_2](ClO_4)_3·2H_2O revealed the formation of a trinuclear complex,in which three tetradentate ligands and two water molecules coordinate to three Zn(II),but the complex inan aqueous solution is present as a monomeric complex ion.Several Zn(II) complexes were found to have invitro insulinomimetic activity which was estimated by the inhibition of free fatty acid release in isolateed rat adipocytes treated with epinephrine.It was revealed that the insulinomimetic activities of Zn(II) complexes with the stability constants (log beta) less than 11 were higher than that of VOSO_4 and were comparable to that of ZnSO_4 as positive contants (log beta) less than 11 were higher than that of VOSO-4 and were comparable to that of ZnSO_4 as positive controls except in the cases of two complexes with Gly derivatives,Zn(N,N-dipyridylmethyl-Gly) and Zn(N,N'-trimethylene-bis-Gly).