Products of Sulfide/Selenite Interaction Possess Antioxidant Properties, Scavenge Superoxide-Derived Radicals, React with DNA, and Modulate Blood Pressure and Tension of Isolated Thoracic Aorta

Selenium (Se), an essential trace element, and hydrogen sulfide (H2S), an endogenously produced signalling molecule, affect many physiological and pathological processes. However, the biological effects of their mutual interaction have not yet been investigated. Herein, we have studied the biological and antioxidant effects of the products of the H2S (Na2S)/selenite (Na2SeO3) interaction. As detected by the UV-VIS and EPR spectroscopy, the product(s) of the H2S-Na2SeO3 and H2S-SeCl4 interaction scavenged superoxide-derived radicals and reduced ⋅cPTIO radical depending on the molar ratio and the preincubation time of the applied interaction mixture. The results confirmed that the transient species are formed rapidly during the interaction and exhibit a noteworthy biological activity. In contrast to H2S or selenite acting on their own, the H2S/selenite mixture cleaved DNA in a bell-shaped manner. Interestingly, selenite protected DNA from the cleavage induced by the products of H2S/H2O2 interaction. The relaxation effect of H2S on isolated thoracic aorta was eliminated when the H2S/selenite mixture was applied. The mixture inhibited the H2S biphasic effect on rat systolic and pulse blood pressure. The results point to the antioxidant properties of products of the H2S/selenite interaction and their effect to react with DNA and influence cardiovascular homeostasis. The effects of the products may contribute to explain some of the biological effects of H2S and/or selenite, and they may imply that a suitable H2S/selenite supplement might have a beneficial effect in pathological conditions arisen, e.g., from oxidative stress.