Synthesis and characterization of highly pure form of sodium salt of anionic, thiomalatogold(I) complex with antiarthritic activity. Analogs of anionic, thiomalatosilver(I) complex with antimicrobial activity

Article abstract of DOI:10.1246/bcsj.68.2875

Sodium salt of anionic Au(I) complex with a trianion of thiomalic acid tma^3- (H₃tma=HOOCCH(SH)CH₂COOH), known as an effective antiarthritic drug, was prepared in highly pure form by one-step synthesis from NaAuCl₄ and tma^3- in aqueous solution. The reaction consisted of a reduction of Au(III) by tma^3- and the following complexation of Au(I) with tma^3- ligand. The disulfide species of tma^3- formed by this reduction was removed by passing through an anion-exchange resin column and the contaminating NaCl by passing through a gel filtration column. The tma-Au(I) complex was also prepared by another reaction based on ligand exchange of the intermediate complex AuCl(thiodiglycol) with tma^3-. It was purified using the anion-exchange resin and gel filtration columns. The target compound, finally isolated in 30% yield in highly pure form, has been characterized by complete elemental analyses, TG/DTA, FT-IR, ¹H and ¹³C NMR spectroscopies, and molecular weight was determined in aqueous solution by molmass measurement based on the cryoscopic method combined with dissociation degree determination based on the [Na⁺] measurement in equilibrium state using a Na⁺-ion selective electrode. This Au(I) complex was an oligomer with a formula of {Na₂[Au(tma)] · 1.75H₂O}(n) (n = 3-10; MW = 1260-4220).This polymerization degree, low in comparison with previously proposed data, was determined in the neutral aqueous solution without any other electrolytes under the concentration range C(Na) = 0.914-182.9 mmol dm^-3. The tma-Au(I) complex exists in an oligomeric form both in the solid and in aqueous solution. The properties of the oligomeric tma-Au(I) complex were compared with those of the previously reported complex and a commercially available sample, and also with those of the recently prepared, oligomeric tma-Ag(I) complex with antimicrobial activity.