Аnti-human melanoma effect of Fe(III)-containing Wells-Dawson polyoxotungstate and ascorbate: optimization of concentration ratio

In this study, the anti-human melanoma A375 effect of Fe(III)-substituted monolacunary WellsDawson polyoxometalate (Fe-WD), K7[FeIII(α2-P2W17O61)(H2O)] and L(+)-ascorbic acid sodium salt (ascorbate) mixed in the concentration ratios of 1:1 and 1:5 was evaluated. Exponentially growing A375 cells were exposed in vitro to Fe-WD, ascorbate, and Fe-WD/ascorbate mixtures for 48 and 72 h, at 37 °C. Fe-WD, ascorbate, and their mixtures resulted in concentration- and time-dependent cytotoxic actions with different potencies against A375 cells. The results of the simultaneous exposure to equimolar Fe-WD/ascorbate mixtures indicated an additive inhibitory effect of the mixture components on A375 cell viability. The equimolar Fe-WD/ascorbate ratio was found to be more favourable compared with the 1:5 Fe-WD/ascorbate ratio which demonstrated an antagonistic cytotoxic action of the studied compounds on A375 cells. Although the equimolar ratio is more suitable in the context of the potential pharmacological application of Fe-WD as an antitumor drug candidate in combination with ascorbate being commonly prescribed as a supplement therapy, further studies on different FeWD/ascorbate ratios generating abundant free radicals are suggested to find a more potent antitumor activity.