Flavonoid Contents of Propolis from the West Side of Romania and Correlation with the Antioxidant Activity

Propolis is a gum-like product which are gathered by bees from various plants, and which vary in color from light yellow to dark brown. It is known that the propolis have antibacterial, anticarcinogenic, and immunostimulating biological activities. Parts of these activities are probable due to the antioxidative effect of some compounds which occur in relatively higher concentrations in propolis (especially flavonoids). In this paper are presented the identification and quantification by HPLC analysis of the main flavonoids from propolis collected from the west side of Romania and the correlation of the antioxidative activity of the propolis extracts (evaluated by the DPPH method) with the flavonoidic contents. The significative concentration was observed for quercetin and rutin, caffeic acid, and chrysin; other flavonoids were apigenin and kaempferol (up to 5 mg/g). The antioxidative activity was significative for the 60% and 96% ethanol propolis extracts and this activity has a good correlation with the propolis flavonoid concentrations. The rate of the DPPH consuption in the presence of these extracts were up to tens μM/s, this rate being in good correlation with the flavonoid concentration of the propolis extracts.