Research noteIsolation and identification of compounds from the ethanolic extract of flowers of the tea (Camellia sinensis) plant and their contribution to the antioxidant capacity
Introduction
Numerous in vitro and vivo studies reported beneficial health properties of tea leaves and their phenolic compounds (Bushman, 1998, Trevisanato, 2000). However, less attention has been given to these properties of flowers of the tea (Camellia sinensis) plant. This is due to the fact that people have been only picking the tender shoots from tea plants to manufacture tea since a long time. Some chemicals, such as ethephon and naphthalene acetic acid, have been employed to inhibit the blossoming of tea and promote the production and quality of tea (Lin, Wu, & Lin, 2003).
Compared to tea leaves and teas, tea flowers have similar chemical compositions and contain comparable amounts of total catechins but less caffeine (Lin et al., 2003, Su et al., 2000). Furthermore, floratheasaponins were firstly found in the tea flowers and showed potent inhibitory activities on serum triglyceride elevation and the release of β-hexosaminidase from RBL-2H3 cells (Yoshikawa et al., 2005, Yoshikawa et al., 2007). Moreover, the tea flower extracts exhibit strong hydroxyl radical-scavenging effects in the Fenton reaction system and nitric oxide suppressing effects in LPS-induced RAW 264.7 cells (Lin et al., 2003). We have reported that the ethanolic extract from the tea flower possessed the stronger scavenging activity to hydroxyl radical and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical than the water extract (Yang, Xu, Jie, He, & Tu, 2007). Now it is important to determine the major active components responsible for the antioxidant activity of tea flowers.
The aims of the present study were to ascertain the profile and identity of the antioxidative active compounds isolated from the ethanolic extract of the tea flowers using liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) techniques and elucidate their contribution to the total antioxidative activity.
Section snippets
Chemicals
DPPH, ascorbic acid (AA) and the eight catechins, namely, catechin (C), epicatechin (EC), gallocatechin, epigallocatechin (EGC), gallocatechin gallate, epigallocatechin gallate (EGCG), catechin gallate, and epicatechin gallate (ECG), were purchased from Sigma Chemical Co. (St. Louis, MO, U.S.A.).
Preparation of the extracts from the tea flowers
The experiments for ethanolic extraction were performed in triplicate. Three batches of lyophilized and powdered tea flowers (C. sinensis cv. ‘Longjin43’, from the Tea Resource Garden of Zhejiang
Results and discussion
The inhibiting abilities of the extracts of the tea flowers on DPPH were ranked by 50%-inhibition concentrations (IC50). The lower IC50 value implies the higher antioxidant activity. Upon regression analysis of scavenging rate (%) and the natural logarithm of the extracts concentration, a good linear relationship was observed between these two parameters, and the regression equations and correlation coefficients are listed in Table 1. With regression equations derived, it was easy to calculate
Acknowledgments
We are grateful to Mr. Yagi, A. at Shizuoka University in Japan, who carried out the NMR measurements.
References (15)
- et al.
Myricetin 3-rhamnosyl (1 → 6) galactoside from Nymphaéa x Marliacea
Phytochemistry
(1998) - et al.
Flavonol glycosides from flowers of Crocus speciosus and C. antalyensis
Phytochemistry
(1999) - et al.
Tea and tea polyphenols in cancer prevention
The Journal of Nutrition
(2000) - et al.
Suppression of free-radicals and protection against H2O2-induced oxidative damage in HPF-1 cell by oxidized phenolic compounds present in black tea
Food Chemistry
(2007) Green tea and cancer in humans: a review of the literature
Nutrition and Cancer
(1998)- et al.
Determination of tea polyphenols and caffeine in tea flowers (Camellia sinensis) and their hydroxyl radical scavenging and nitric oxide suppressing effects
Journal of Agricultural and Food Chemistry
(2003) - et al.
Inhibition of angiotensin converting enzyme (ACE) by flavonoids isolated from Ailanthus excelsa (Roxb) (Simaroubaceae)
Phytotherapy Research
(2007)
Cited by (57)
Physiological genetics, chemical composition, health benefits and toxicology of tea (Camellia sinensis L.) flower: A review
2020, Food Research InternationalCitation Excerpt :The contents of catechins and caffeine of tea flowers vary among different varieties, regions and extraction methods. As shown in Table 3, eight catechins are found in tea flowers, including (+)-catechin (C), (−)-epicatechin (EC), (−)-epigallocatechin 3-O-gallate (EGCG), EGC, ECG, (−)-gallocatechin, (+)-catechin-3-O-gallate and (−)-gallocatechin-3-O-gallate (Lin et al., 2003; Morikawa, Ninoniya et al., 2013; Yang et al., 2009). The concentrations of total catechins and caffeine are 2.45–39.12 and 3.48–10.70 mg/g, respectively (Lin et al., 2003; Morikawa, Ninoniya et al., 2013).
Biogenic fabrication of nanomaterials from flower-based chemical compounds, characterization and their various applications: A review
2020, Saudi Journal of Biological SciencesStudy of the biochemical formation pathway of aroma compound 1-phenylethanol in tea (Camellia sinensis (L.) O. Kuntze) flowers and other plants
2018, Food ChemistryCitation Excerpt :Tea flowers have similar chemical compositions to tea leaves. Polyphenols, such as catechins and flavonols, methylxanthines, such as caffeine, and amino acids, such as theanine, are representative metabolites in tea leaves (Wan and Xia, 2015) that are also found in tea flowers (Lin, Wu, & Lin, 2003; Wang et al., 2010; Yang et al., 2009). Furthermore, tea flowers contain predominant amounts of functional molecules that occur in tea leaves in lower or trace amounts, such as floratheasaponins (Matsuda, Nakamura, Morikawa, Muraoka, & Yoshikawa, 2016) and spermidine derivatives (Yang et al., 2012).