Antioxidant effects and bioavailability evaluation of propolis extract and its content of pure polyphenols

Propolis is a resinous mixture which honey bees collect from buds and bark of some trees. It contains several antioxidant compounds such as polyphenols and flavonoids. This paper describes the antioxidant capacity of propolis extracts and pure polyphenols in vivo. Several biological parameters were measured after promoting oxidative stress. All the homeostasis changes and liver, kidney, and lung damage were restored by propolis extract. Propolis extracts directly modulated lipid peroxidation where LDL level decreased from 1.3 to 0.8 g/L after giving propolis, illustrating the antioxidant contribution of propolis. Finally, orally administered pure antioxidant compounds such as caffeic acid, quercetin, and kaempferol at the doses corresponding to in vitro antioxidant capacity of the propolis extract did not restore the physiological parameters. Bioavailability study demonstrated that the isolated polyphenols have lower absorption (plasma Cmax of polyphenols = 15–20 µg/mL) than the complex extract of propolis (plasma Cmax of polyphenols = 40–50 µg/mL). Practical applications Extracts of propolis showed significant reduction of oxidative damages from oxidative stress. The complexity of propolis has an antioxidant capacity more than its isolated polyphenols. Monitoring the concentrations of the compounds in serum after orally administering of propolis and isolated polyphenols demonstrated that these antioxidant compounds have higher bioavailability when applied as crude extracts. These results make the propolis extracts a promising antioxidant which could be used as a food supplement.