Characterization of the Constituents and Antioxidant Activity of Brazilian Green Tea (Camellia sinensis var.assamica IAC-259 Cultivar) Extracts

摘要

Freeze-dried extracts from Camellia sinensis var.assamica IAC-259 cultivar named Brazilian green tea were prepared by hot water and ultrasound-assisted extractions using leaves harvested in spring and summer.Their caffeine and catechin contents were measured by high performance liquid chromatography-diode array detector.The antioxidant activity of the major green tea compounds and Brazilian green tea extracts was evaluated using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay.The levels of caffeine were higher in the summer samples (p < 0.05);otherwise,there were no significant variations related to the catechin contents between spring and summer samples.The sonication method using water/acetone as solvent had a high efficiency to extract not only epigallocatechin gallate but also epicatechin gallate (p < 0.05).Antioxidant activities of the Brazilian green tea extracts were not significantly different among seasons and extraction systems.The antioxidant data (IC50) of the Brazilian green tea extracts showed a significant correlation with their epigallocatechin gallate and epicatechin gallate contents (p < 0.05).