A comparative study of antioxidative activity of calcium-D-glucarate, sodium-D-gluconate and D-glucono-1,4-lactone in a human blood platelet model.

D-glucono-1,4-lactone, sodium D-gluconate and calcium D-glucarate are non-toxic glucose derivatives occurring naturally in fruits and vegetables. Calcium D-glucarate is promoted as an orally bioavailability dietary supplement with potential chemopreventive activity without adverse effects. Despite many commercial applications in pharmaceutical and food industries the potential activity mechanisms of glucarate and gluconate are not clear. The purpose of this study was to investigate and compare the effects of these compounds on blood platelets under oxidative stress conditions and to examine their role in thrombin-induced platelet activation. Platelet activation is essential in haemostasis, tumor progression and allergic and non-allergic inflammation, where reactive oxygen species are involved. The antiplatelet and antioxidative activity was studied in vitro by measuring levels of specific oxidative stress markers: thiobarbituric acid reactive substances, superoxide anion, carbonyl groups, 3-nitrotyrosine, protein and low molecular weight thiols. All tested compounds significantly inhibited thrombin-induced arachidonic peroxidation, O₂⁻ⁱ production and also platelet protein oxidation/nitration induced by peroxynitrite, which is a strong oxidant formed intravascularly in vivo. Carbonyl group generation, thiol oxidation and nitrotyrosine formation were significantly decreased in the presence of glucose derivatives. The obtained results demonstrate that tested compounds may be helpful in the prevention of excessive platelet activation through the antioxidant mechanisms. Comparative studies indicate the predominant preventive activity of sodium D-gluconate. In general, the consumption of apples or apple juice as well as oranges, grapefruit and cruciferous vegetables, sources of large amounts of tested derivatives, have beneficial effects on platelets under oxidative stress.