Comparison of in vitro antioxidant activities and bioactive components of green tea extracts by different extraction methods

In this study, in vitro antioxidant activities and bioactive components of green tea extracts (GTE) by ultrahigh pressure extraction and conventional extraction methods (microwave extraction, ultrasonic extraction, Soxhlet extraction and heat reflux extraction) were investigated. DPPH radical-scavenging and FTC method were applied to test the antioxidant activities. The bioactive components were determined by chemical methods. The results indicated that the GTE by ultrahigh pressure extraction exhibited the strongest antioxidant activities. The contents of polyphenols and catechins in the GTE by ultrahigh pressure extraction were significantly higher than those by other extraction methods, which was possibly responsible for the higher antioxidant activities of the GTE by ultrahigh pressure extraction. From the results we can draw the conclusion that not only the more bioactive components are obtained but also the extract has better free radical and reactive oxygen species scavenging activities through ultrahigh pressure extraction method. These findings further illustrate that ultrahigh pressure extraction has a bright prospect for extracting active ingredients from plant materials. (C) 2011 Elsevier B.V. All rights reserved.