Antioxidant Properties and Phenolic Composition of Propolis from Diverse Geographic Regions in Korea

Abstract

Propolis is a resinous substance collected by honeybees from various plant sources. In this study, we examined the antioxidant properties of propolis from diverse geographic regions of Korea including Jeju Island. Ethanol extracts of propolis (EEP) were prepared and evaluated for their antioxidant properties by β-carotene bleaching, 1,1-diphenyl-2-picrylhydrazyl free radical-scavenging, 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation decolorization, and ferric reducing/antioxidant power assays. Furthermore, the major constituents in EEP were identified by HPLC analysis with a photodiode array and mass spectrometric detection, and each component was quantitatively analyzed. All propolis samples except that from Hongcheon, Iksan, Aewol and Pyoseon had relatively strong antioxidant activity accompanied by high total polyphenol contents. Propolis with strong antioxidant activity contained large amounts of antioxidative compounds, such as caffeic acid, kaempferol, phenethyl caffeate and galangin. On the other hand, propolis from Jeju Island had weak antioxidant activities and had only a few compounds in propolis from other regions.