Comparisons of antioxidant activity and total phenolics of Camellia oleifera Abel fruit hull from different regions of China

Abstract

The tea oil camellia, Camellia oleifera Abel, is used extensively in China as cooking oil. The antioxidant and antiradical activities of five C. oleifera fruit hull extracts from the major producing regions of China were examined. The content of total phenolics and extractable condensed tannins (ETC) in the extracts was calculated. Remarkable high phenolic content (gallic acid equivalent, GAE > 144 mg/g), extractable condensed tannin content (ETC > 96 mg/g), strong reducing ability (ascorbic acid equivalent, AAE > 5.5 mg/g) and antiradical activity (IC50 < 2.1 mg/ml) were found in samples from Guangxi, Jiangxi, Hunan and Zhejiang. The best results were obtained for the samples from Guangxi (phenolic content as GAE = 234.90 mg/g, extractable condensed tannin content as ETC = 166.98 mg/g, reducing power as AAE = 12.91 mg/g and DPPH radical-scavenging ability as IC50 = 899.25 µg/ml). A significant correlation was observed between reducing ability and the content of phenolic compounds of respective extracts. Phenolic compounds of extracts were analyzed by HPLC, and the gallic acid was found to be the predominant phenolic acids constitute. This result suggests the potential ofC. oleifera fruit hull for the utilization as the source of natural antioxidant. Key words: Camellia oleifera Abel, total phenolics, reducing power, radical-scavenging ability.