Identification and Quantification of Free Radical Scavengers in Pu-erh Tea by HPLC-DAD-MS Coupled Online with 2,2′-Azinobis(3-ethylbenzthiazolinesulfonic acid) Diammonium Salt Assay

Abstract

Pu-erh tea, a well-known traditional beverage in China, has attracted more attention because of its beneficial health effects and special flavor and taste. Generally, it is believed that Pu-erh tea with a longer preservation period has better quality and taste. Antioxidant activity is one of the major beneficial activities of tea. In this study, a HPLC-DAD-MS coupled with 2,2'-azinobis (3-ethylbenzthiazolinesulfonic acid) diammonium salt (ABTS) assay was employed for identification and quantification of free radical scavengers in different samples of Pu-erh tea. Among 12 main peaks detected in Pu-erh raw tea, 11 compounds were identified as gallic acid, (-)-gallocatechin, (-)-epigallocatechin, (+)-catechin, caffeine, (-)-epicatechin, (-)-epigallocatechingallate, rutin, (-)-epicatechingallate, quercetin-3-glucoside, and kaempferol-3-glucoside by comparison of their UV and MS data with standard compounds or literature data, respectively. The contents of 12 investigated compounds were also determined or estimated using caffeine, (-)-epicatechin, or rutin as standard. ABTS assay showed that 10 out of 12 compounds were free radical scavengers. Their total amount was used as the marker for evaluation of free radical scavenging activities of different Pu-erh teas, which indicated that the activity of different Pu-erh teas varied; Pu-erh raw tea was stronger than the ripe one, and the activity decreased with the increase of preservation period.

Pu-erh tea tasting in Yunnan, China: Correlation of drinkers’ perceptions to phytochemistry

“…The higher TCC and free radical scavenging capacity of green pu-erh samples compared to aged green and black pu-erh samples are consistent with previous studies on a decrease in polyphenolic levels and anti-oxidant activity of pu-erh and other teas with an increase in processing and aging (Qian et al, 2008;Ku et al, 2010;Wang et al, 2010). The variability between samples based on production and processing highlights the importance of sampling protocols to include a range of production variables.…”

An Up-to-Date Review of Phytochemicals and Biological Activities in Chrysanthemum spp

“…However, some currently used synthetic free radical scavengers have been demonstrated various side effects 41,42 . Therefore, functional foods become a promising source of natural antioxidants 43,44 . It is noteworthy to mention here that Chrysanthemum spp.…”

Steamed ginger (Zingiber officinale): Changed chemical profile and increased anticancer potential

“…Since the detection and structural characterisation of chemical constituents contained in herbal are often challenging and become the major obstacle for the further pharmacological investigation, it is prerequisite to develop sensitive and reliable analytical methods for the identification of pharmacological active constituents (Qian, Guan, Yang, & Li, 2008). The coupling of HPLC and MS has advanced the online identification of the constituents in ginger samples.…”