6533b82cfe1ef96bd128e97f

RESEARCH PRODUCT

The interaction of organotins with native DNA

subject

description

The compounds R2SnCl2 and R3SnCl (RMe, Et, nBu, nOct, Ph, in ethanol solution) as well as the aqueous species [Me2Sn(OH2)n]2+ and [Me3Sn(OH2)2]+, react with aqueous native DNA, yielding solid phases. According to the pointcharge model treatment of the 119Sn Mossbauer parameter nuclear quadrupole splitting, trans-octahedral R2Sn(O2PXY)2, and trigonalbipyramidal R3Sn(O2PXY), (RMe, Et, nBu), would occur in the pellets, the tin atoms being coordinated by phosphodiester groups of the nucleic acid. The precipitates from Ph2SnIV would consist of the DNA complex as well as of the Ph2SnIV distannoxane obtained by hydrolysis of the reactant, whilst nOct2SnCl2, nOct3SnCl and Ph3SnCl would mainly yield stannoxanes and hydroxides. The water-soluble hydrolyzed species [Me2Sn(OH)(OH2)n]+, Me2Sn(OH)2 and Me3Sn(OH)(OH2) do not show any interaction with native DNA, although they are possibly coordinated by phosphate oxygen atoms in model aqueous systems, in the presence of excess ligand. These trends have been rationalized by QSAR approach (Quantitative Structure-Activity Relationships) in terms of electronic factors related to tin-oxygen (phosphate) Coulomb interactions, as well as the lipophilicity of R in the RnSnIV moieties.