Spectroscopic investigation of organotin (IV) derivatives of 7-epiclusianone : a preliminary in vitro antitumor evaluation of HN-5 human carcinoma cell.

Abstract

A series of organotin(IV) compounds have been prepared by reaction with 7-epiclusianone (Epi), a natural product extracted from fruits of Rheedia gardneriana. This compound has an interesting motif with several coordinating sites for metal-ligand bond formation, and in solution, it shows a keto-enol tautomerism. The NMR of the organotin(IV) derivatives has revealed intramolecular hydrogen bonding, indicating that the keto-enol tautomerism of 7-epiclusianone is not involved upon coordination of those, but the absence of this bonding type in the case of the SnCl4 derivative suggests a strong interaction. The Mössbauer spectroscopy has revealed five- and six-fold coordination for the organotin(IV) and SnCL» derivatives in the solid state. However, in solution all tin complexes have six-fold coordination, as shown by "9Sn NMR. The overall data point out that the organotin(IV) precursors SnClxPri4_x (x = 1, 2) are weakly bonded to the 7- epiclusianone, except the SnC^. Bioassay in vitro of the substance test [SnClPh3(£/7/)] (1) has been investigated using two epithelial cells: normal MDCK from canine kidney, and IIN-5 from a human carcinoma of the tongue. The results clearly demonstrate that the time for cellular reproduction has been reduced in the presence of the substance test.