Characterisation of polyphenol constituents of Linderae aggregate leaves using HPLC fingerprint analysis and their antioxidant activities

The leaves of Linderae aggregate (LAL) has been used as a type of tea in China and other Southeast Asian countries. In this study, 11 polyphenols in LAL were clarified for the first time using multiple high-performance liquid chromatographic techniques. An optimal extracting method was developed through the comparison of the amount of quercetin-3-O-alpha-L-rhamnoside using a uniform design method. From the fingerprint liquid chromatography data, 11 common peaks in the 8 samples collected from April to November were semi-determined. The antioxidant capacities were examined using the 2,2-diphenyl-1-picrylhydrazyl free radical scavenging assay and the ferric reducing/antioxidant power assay. All 8 samples contained the same 11 polyphenols in similar ratios. Three samples, S2, S5 and S6 contained higher amount of quercetin-3-O-alpha-L-rhamnoside and were demonstrated to have stronger antioxidant capacities in both antioxidant assays. These results are critical in optimising harvest time and quality control of LAL. (C) 2014 Elsevier Ltd. All rights reserved.