Structure‐activity relationships for organotin compounds

Abstract

The LC50 concentrations of a series of 15 structurally distinct diorganotins (R2SnX2) and triorganotins (R3SnX) were determined for zoeae of the mud crab Rhithropanopeus harrisii. Zoeae were exposed from hatching until metamorphosis, at ˜14 d. The LC50 values varied by almost 4 orders of magnitude, from the least toxic aquated species, dimethyltin (LC50 = 92,276 nM) to the most toxic, tricyclohexyltin (LC50 = 19.8 nM). Within a homologous series, the diorganotin was less toxic than the corresponding triorganotin, but the toxicity of the two classes overlapped, e.g., dicyclohexyltin was more toxic than trimethyltin and about as toxic as triethyltin. Correlations between the Hansch π parameter and the LC50, and between total surface area and the LC50, suggest that aqueous thermodynamic activity (hydrophobicity), a function of the organic ligand attached to tin, controls bioconcentration and thus the lethal dose. This conclusion is substantiated by the observation of a single linear relationship between a sum of Hansch fragment constants and the LC50 values for both the di‐ and triorganotins. The difference in toxicity between di‐ and trialkyltins results from a decrease in hydrophobic character when a hydroxyl group is substituted for an organic ligand in the former. Any electronic effect of the organic ligand is overwhelmed by the factors that control hydrophobic behavior, as evidenced by the observed poor correlations with χ.

Toxicity of butyltin, phenyltin and inorganic tin compounds to sulfate-reducing bacteria isolated from anoxic marine sediments

“…14,15 Previous studies on a wide variety of organisms (eukaryotes and prokaryotes) showed that trisubstituted tin compounds were more toxic than their tetra-and mono-substituted counterparts. 12,13,[16][17][18][19][20] Some of this work also demonstrated that OT toxicity was dependent on the nature of the substitutents. 12,18 Various parameters have been tested to estimate relationships between molecular structure and biological activity, especially those that represent the hydrophobicity of the molecules.…”

“…However, its toxic effects are not fully known. 12,13 It is generally believed that the toxicity of organotin compounds increases with increasing size of the alkyl group of the OT molecule and with increasing substitution of the tin atom. 14,15 Previous studies on a wide variety of organisms (eukaryotes and prokaryotes) showed that trisubstituted tin compounds were more toxic than their tetra-and mono-substituted counterparts.…”

Response of Bioluminescent Bacteria to Alkyltin Compounds

“…Although data on water-octano1 partition coefficients and on correct values for the metal-substituent bonds to calculate the Hanch pi parameters are not available Laughlin et a1. (18) showed correlation between toxicity to mud crab larvae and the Hansch pi parameter for the carbon chain fragment. Using bioluminescent bacteria, we could show correlation only for the trialkyltins from methyl through butyl only.…”

Inorganic Materials Biotechnology: A New Industrial Measurement Challenge

“…As ultratrace chemical speciation methods have gained favor and applicability, evidence has grown to support novel use of molecular topology arguments as structure-activity predictors for cell uptake of several metal species, notably tin [39]. Transmission of certain cheurical forms of metals and metalloids across membranes occupies much attention of toxicologists and molecular geneticists [40] but much additional research is needed to complete our understanding of superficial membrane complexation of metal and metalloid ions, their entry into cell interiors and their ultimate fate.…”