Transition Metal Complexes of 2-methoxybenzaldehyde-N-(5-chloro-2-oxo-1, 2- dihydro-3H-indol-3-ylidene) hydrazone as New Tyrosinase Inhibitors: Design, Structural Description & In-Vitro Assessment

The copper-containing tyrosinase is a trans-membrane glycoprotein responsible for catalyzing the rate limiting steps in mammalian melanogenesis, resulting in darker skin color and some dermatological disorders, e.g. melasma, age spots and sites of actinic damage. There are limited studies available on this enzyme in general and limited potent inhibitors are reported in particular. This led us to search for some new potent inhibitors for this enzyme. In this study a new series of coordination compounds from Co (II), Ni (II), Cu (II) and Zn (II) have been synthesized using an isatin derived hydrazone ligand i.e. 2- methoxybenzaldehyde-N-(5-chloro-2-oxo-1,2-dihydro-3H-indol-3-ylidene)hydrazone. Structural characterization of synthesized complexes was carried out by means of employing standard methods e.g. elemental analysis, magnetic susceptibility measurements, molar conductance measurements, IR and UV-Vis. spectroscopy. The characterization suggested that complexes of Co (II), Ni (II) and Zn (II) acquired octahedral geometry with the bi-dentate ligand, while square plane geometry was deduced for Cu (II) complex. A comparative study for screening tyrosinase inhibitory potential was done for all compounds and it was observed that coordination complexes were more effective inhibitors of tyrosinase when compared to the free ligand.