BIOAVAILABILITY AND IN VIVO ANTIOXIDANT ACTIVITY OF M.E.D.® PROPOLIS EXTRACT

A large body of evidence highlights the biological properties of propolis, which can be ascribed to its antioxidant and anti-inflammatory activities [1]. As bioavailability is an essential measurement tool to show a systemic effect and the bioavailability of propolis is not widely known, the present research aimed to evaluate the bioavailability of a standardized polyphenol mixture obtained from brown propolis, using a patented extraction method called Multi Dynamic Extraction (M.E.D.® propolis), administered under acute and prolonged treatments. First, the content of the main polyphenols of M.E.D.® propolis was evaluate through RP-HPLC-UV-PDA-MSn analysis. The most abundant polyphenols resulted to be galangin and chrysin, which represented the 7.8% and 7.5% of the characterized polyphenols mixture, respectively. Then the bioavailability of galangin and chrysin was determined in 30 males C57BL/6 wild-type mice, 8 weeks old, following acute and prolonged oral administration of the previously characterized polyphenols mixture. In the first case, the acute setting, mice were fed with a single bolus, at the dose of 500 mg/kg body weight, containing 3.65 mg of the polyphenol mixture. While, in the second case, the prolonged setting, mice were fed with 100, 250, and 500 mg/kg bolus, for 30 days. In the acute setting, blood was taken at 30 s and 5, 10, 15, 20, 25, 30, 45, 60 and 120 min, following the administration period, and in the prolonged setting, blood samples were collected at the 10th, 20th, or 30th day of the treatment period. At the end of the both settings, the expression superoxide dismutase (SOD), catalase, and glutathione peroxidase antioxidant enzymes was evaluated in liver tissue. Following both acute and prolonged administration, neither galangin nor chrysin were detectable in the plasma of mice, whereas the glucuronide metabolite of galangin was detectable 5 min after acute administration. At the end of the prolonged treatment SOD increased significantly, unlike the other two enzymes. The obtained data suggest that oral administration of M.E.D.® propolis extract is followed by a rapid absorption and metabolization of galangin. Moreover, an adaptation of the antioxidant first line defense system was observed.