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Abstract

The paper describes addition-nucleophilic reactions of 1-(5-R¹-2-furyl)-2-R²-R³-ethylenes with SH (thioglycolic acid), NH₂ (glycine) and OH (phenol) nucleophiles, and with hydroxyl ions in aqueous media. The determined rate constants, of second order (dm³ mol^-1 s^-1), show that in the physiological conditions the preferential reaction will be that with thiols. The amino acid composition of proteins modified with 1-(5-nitro-2-furyl)-2-nitro-2-methoxycarbonylethylene has revealed that the only group affected was the SH group of cysteine. This finding points out the significance of addition-nucleophilic SH-interactions of 2-furylethylenes with the protein macromolecules and accounts for the high cytotoxicity of these compounds.