Comparative study on antioxidant effects of extracts from Rubus coreanus and Rubus occidentalis

This study compared the antioxidant effects of two kinds of black raspberry extract, obtained from fruits of Rubus coreanus and Rubus occidentalis, which can be found in Korea. The fruits of R. coreanus and R. occidentalis were each extracted with 0%, 25%, 50%, 75%, and 100% ethanol (EtOH). Among the extracts of these two varieties, 50% EtOH extract of R. occidentalis showed the highest contents of total polyphenols (46.96±2.78 mg/g) and flavonoid compounds (11.77±0.81 mg/g). The 50% EtOH extract of R. occidentalis showed the highest antioxidant activity (84.77±0.97%) in terms of DPPH radical scavenging activity. On the contrary, 25% EtOH extract of R. occidentalis showed the best antioxidant activity (29.65±2.41%) in terms of ABTS radical scavenging activity. In the results of ferric reducing antioxidant power (FRAP) assay, 50% EtOH extract of R. occidentalis showed the highest antioxidant activity (0.49±0.02%). In the cytotoxicity test stimulated with H₂O₂, the extracts of 75% and 100% EtOH from R. occidentalis showed the highest cell viability (93.54±3.37% and 97.19±0.74%, respectively). According to our results, extracts of R. occidentalis showed higher antioxidant activities than extracts of R. coreanus. Especially, total polyphenol and flavonoid contents of R. occidentalis showed the highest significant correlation with FRAP by Pearson's correlation (P=0.005 and P=0.013, respectively).