A kinetic study of new polyamine analogs oxidized by bovine serum amine oxidase

Abstract

The low efficacy of drugs currently used in anticancer therapeutic applications and the development of multidrug-resistance prompted us to study the polyamine pathway as a possible target for the development of new anti-proliferative pharmacological agents. In order to develop new amino oxidase (AO) spermine-based ligands, several spermine analogs were synthesized with the aim to improve their enzymatic oxidative deamination. The insertion of thiophene on one of terminal amines and substitution of the inner nitrogen atoms of spermine with oxygens, led to improved kinetic parameters. (Table 1). In fact, a kinetic study showed that Km and kcat (kc) were better than those of the physiological polyamines spermine and spermidine. Kinetic observations were carried out in buffer phosphate 0.01M, at pH 7.4-7.6, in order to perform cytotoxic studies using BSAO enzyme (Bovine Serum Amine Oxidase) in the presence of polyamine analogs on cancer cells. The kinetic assays were performed using the new synthesized compounds in the range between 0.05-1 mM in the presence of BSAO. BSAO catalyzes, in the presence of O2, the oxidative deamination of spermine, spermidine and their analogs, providing the formation of H2O2, aldehyde(s) and NH3. The improvement of the kinetic parameters obtained at pH 7.6, in comparison with that observed at pH 7.4, is probably due to a better interaction between amine-oxidase with the substrates, constituted by polyamine analogs, that leads to the formation of the Schiff base (1,2,3). As future perspective, these molecules will be assayed alone or in combination with BSAO on several cancer cells, with the aim to evaluate their cytotoxic effect, that could be taken into consideration as new approach in anti-cancer therapy