New insulinomimetic zinc(II) complexes of α-amino acids and their derivatives with Zn(N2O2) coordination mode

Zinc(II) complexes of α-amino acids and their derivatives with a Zn(N2O2) coordination mode were found to have in vitro insulinomimetic activity as estimated with the inhibition of free fatty acid release in isolated rat adipocytes treated with epinephrine. It was revealed that the insulinomimetic activities of zinc(II) complexes with over-all stability constants (log β) less than 10.5 are higher than those of ZnSO4 and VOSO4. The high blood glucose level of KK-Ay mice with type 2 diabetes mellitus was lowered by daily intraperitoneal injections of a zinc(II) complex, cis-[Zn(L-Thr)2(H2O)2], for 14d. The improvement of diabetes mellitus was confirmed with the oral glucose tolerance test.