The Mechanism of the Osteoprotective Action of a Polyphenol-Rich Aronia melanocarpa Extract during Chronic Exposure to Cadmium is Mediated by the Oxidative Defense System

Recently, we demonstrated in a rat model that consumption of a polyphenol-rich extract obtained from the berries of Aronia melanocarpa could protect from cadmium-induced disorders in bone turnover and changes in bone mineral status. The aim of this study was to investigate whether the osteoprotective effect of this extract is mediated by the oxidative defense system. Enzymatic and nonenzymatic antioxidants, total antioxidative and oxidative status, hydrogen peroxide, and markers of oxidative protein, lipid, and DNA damage were determined in bone tissue at the distal femoral epiphysis of female Wistar rats receiving 0.1% aqueous A.melanocarpa extract (prepared from the lyophilized commercial extract containing 65.74% of polyphenols) as the only drinking fluid and/or cadmium in the diet (1 and 5mg/kg) for 3, 10, 17, and 24 months. The total oxidative and antioxidative status of the serum was also evaluated. The administration of A.melanocarpa extract provided significant protection from cadmium-induced oxidative stress in the bone and serum, and from lipid peroxidation and oxidative damage to the protein and DNA in the bone tissue. Numerous correlations were noted between indices of the oxidative/antioxidative bone status and markers of bone metabolism previously assayed in the animals receiving A.melanocarpa extract. The results allow the conclusion that the ability of A.melanocarpa extract to mediate the oxidative defense system and prevent oxidative modifications of protein, lipid, and DNA in the bone tissue plays an important role in its osteoprotective action under exposure to cadmium. The findings provide further evidence supporting our suggestion that chokeberry may be a promising natural agent for protection against the toxic action of cadmium in women chronically exposed to this metal.