Introduction to the International Symposium on Chemistry, Flavor, and

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Symposium Introduction

Symposiums Introduction Introduction to International Symposium on Chemistry, Flavor and Health Effect of Teas Da-xiang Li, Yu Wang, Zhengzhu Zhang, Xiaochun Wan, and Chi-Tang Ho J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.9b00719 • Publication Date (Web): 25 Feb 2019 Downloaded from http://pubs.acs.org on February 27, 2019

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Journal of Agricultural and Food Chemistry

Symposium Introduction

Introduction to International Symposium on Chemistry, Flavor and Health Effect of Teas

Daxiang Li, †,‡ Yu Wang, ≠ Zhengzhu Zhang,†,‡ Xiaochun Wan†,‡,* and Chi-Tang Ho‡,§,* †State

Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, 130

West Changjiang Road, Hefei 230036, China ‡International

Joint Laboratory on Tea Chemistry and Health Effects, Anhui Agricultural

University, 130 West Changjiang Road, Hefei 230036, China ≠Citrus

Research and Education Center, University of Florida, 700 Experiment Station Road,

Lake Alfred, Florida 33850, USA §Department

of Food Science, Rutgers University, New Brunswick, NJ, 08901, USA

*Corresponding

Authors

Dr. Chi-Tang Ho (Tel: 1-848-932-5553; Fax: 1-732-932-6776; E-mail: [email protected]) Or Dr. Xiaochun Wan (Tel/Fax: 86-551-65786765; E-mail: [email protected])

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ABSTRACT A symposium entitled “ Chemistry, Flavor and Health Effects of Teas” was held at the 256th American Chemical Society (ACS) Meeting in August 2018 in Boston, MA, and was sponsored by the ACS Division of Agricultural and Food Chemistry and the International Joint Laboratory on Tea Chemistry and Health Effects, Anhui Agricultural University, China. The purpose of the symposium was to bring together the leading tea researchers throughout the world to discuss the current state of knowledge as well as research needs with respect to chemistry and health beneficial properties of tea. Speakers from North America, Europe, and Asia delivered a total of 35 oral presentations. The presentations covered such diverse topics as polyphenol chemistry and flavor chemistry of teas, metabolomics application to identify the changes of phytochemical composition during processing, as well as the health beneficial effects of drinking teas. This paper is intended to provide a brief summary of the presentations.

KEYWORDS: Tea, polyphenols, metabolomics, disease prevention


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International Symposium on “Chemistry, Flavor and Health Effects of Teas” was organized by the International Joint Laboratory on Tea Chemistry and Health Effects, Anhui Agricultural University, China; and the Division of Agricultural and Food Chemistry, American Chemical Society (ACS), USA and held August 19-23, 2018 in conjunction with the 256th American Chemical Society National Meeting in Boston, MA. The symposium consisted of 35 oral presentations and 12 poster presentations.

Polyphenolic Chemistry of Teas Tea (Camellia sinensis) has important physiological properties and health promoting benefits due to the presence of some phytochemicals, particularly polyphenols.1 To date, the understanding of polyphenolic chemistry of tea has rapidly progressed due to the application of high accuracy techniques such as NMR and LC-MSn. A growing number of novel compounds in tea have been detected, isolated and identified, especially catechin-carbonyl or catechin-theanine conjugates.2-5 In this special issue, Meng et al.6 discuss the formation of these conjugates through the nucleophilic properties of tea catechins. The conjugate products identified after catechins trapping reactive carbonyl species, such as catechin-methyl glyoxal, are definite evidence that catechins possess excellent inhibitory effects on advanced glycation end products and may be beneficial in the fight against diabetes and its complications. With the use of high performance liquid chromatography/ion-trap mass spectrometry, Yang and Tomás-Barbrán7 report that tea is a rich source of ellagic acid and ellagitannins. Their gut microbiota produced metabolites, urolithins were detected first time in human urine after dietary tea beverage intake. Contribution of Tea Polyphenols as Quality Markers of Teas Using Metabolomic Approach



Metabolomics has become a new and robust tool of untargeted analysis of plant and bio-samples. Though the metabolomics method requires identification of all metabolites present in the samples, combining metabolomics techniques with statistics methods give a comprehensive view that reveals the relationship between metabolomes of plants and their quality.8 Liquid chromatography coupled with mass spectrometry analysis has been successfully applied in the research of primary and secondary metabolites in tea plants and provides relevant results in terms of tea grade, harvest season, manufacturing process and others. A typical example is given in this special issue. Wang et al.9 used fresh leaves from a single cultivar C. sinensis Longjing 43 to perform six tea processing methods, and the made teas were evaluated by targeted and untargeted chromatographic procedures. Targeted assessment of the total catechin content identified three clusters: yellow-green, oolong-white-dark, and black. However, principal component analysis of the total tea metabolome identified four chemical phenotypes: greenyellow, oolong, black-white, and dark. Overall, this study identified a wide range of chemicals that are affected by commonly used tea processing methods and potentially affect the bioactivity of various tea types. Multiple kinds of polyphenol-related metabolites of tea are considered as biomarkers of tea quality and bioactivities. The latest study was conducted on different grade of Keemun black tea (KBT) and used untargeted metabolomics to identify and screen grade-related marker compounds by LC-Orbitrap-MS analysis. The researchers posted that 28 compounds were considered as grades marker and 13 compounds were responsible for anti-glycemic activity of KBT, including afzelechin gallate, kaempferol-glucoside and theasinensin A.10 Very recently, Dai et al. used LC-MS-based metabolomics to show that 8-C-N-ethyl-2-pyrrolidone substituted flavan-3-ols instead of flavan-3-ols could be used as markers for long-term storage of white


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tea.11 Similarly, in this issue Zhou et al.12 studied the chemical changes of large-leaf yellow tea during processing. Large-leaf yellow tea is made from mature tea leaves with stems that undergo unique high temperature roasting. Samples were collected from each step for quantitative and qualitative analyses by high-performance liquid chromatography and liquid chromatography– mass spectrometry (LC-MS). LC-MS-based nontargeted and targeted metabolomics analyses revealed that the tea sample after roasting was markedly different from samples before roasting, with the levels of epicatechins and free amino acids significantly decreased, whereas the epimerized catechins dramatically increased. Again, N-ethyl-2-pyrrolidinone-substituted flavan3-ols were found to be the marker compounds responsible for the classification of all samples. With the development of untargeted metabolomics, increasing markers of various teas will be explored in the future.

HEALTH EFFECTS OF TEA Traditional tea drinking is mostly driven by its flavor and stimulant effect. However, nowadays, tea drinking has become part of a phenomenal global culture that is mainly attributed to its biological functionality and potential beneficial health effects. 13-15 Indeed, polyphenolic compounds in tea have many health promoting activities due to their diverse biological actions including antioxidant, anti-inflammatory, anti-tumor and metabolic regulatory effects that could lead to cancer prevention and protect against metabolic, cardiovascular and inflammatory diseases.15 During this symposium, Yang and Zhang16 present a brief overview of studies on the prevention of cancer and cardiometabolic diseases by tea. Their review focuses on gren tea catechins concerning the effective doses used, the mechanisms of action, and possible toxic effects. In addition to polyphenols, tea polysaccharides are also regards as important bioactive



constituent. Chen et al. 17 review the recent studies on the reducing effects of tea polysaccharides on the risk of type 2 diabetes, obesity and other metabolic diseases. Among the mechanisms studied, the role of microbiota is probably most attractive.

ACKNOWLEDGEMENT We thank the ACS Division of Agricultural and Food Chemistry for sponsoring the symposium and the symposium speakers and attendees for their informative presentations and lively discussions. We are grateful to Thomas Hofmann, Ivonne Hofmann-Sellier, for the invitation to publish papers corresponding to symposium presentations and facilitating the manuscript submission and review process.

REFERENCES 1. Wang, Y.; Ho, C. T. Polyphenolic chemistry of tea and coffee: A century of progress. J. Agric. Food Chem. 2009, 57(18), 8109−8114. 2. Lo, C. Y.; Li, S.; Tan, D.; Pan, M. H.; Sang, S.; Ho, C. T. Trapping reactions of reactive carbonyl species with tea polyphenols in simulated physiological conditions. Mol. Nutr. Food Res. 2006, 50(12), 1118−1128. 3. Meng, X. H.; Zhu, H. T.; Yan, H.; Wang, D.; Yang, C. R.; Zhang, Y. J. C-8 N-Ethyl-2pyrrolidinone-substituted flavan-3-ols from the leaves of Camellia sinensis var. pubilimba. J. Agric. Food Chem. 2018, 66, 7150–7155. 4. Li, X.; Liu, G. J.; Zhang, W.; Zhou, Y. L.; Ling, T. J.; Wan, X. C.; Bao, G. H. Novel flavoalkaloids from white tea with inhibitory activity against the formation of advanced glycation end products. J. Agric. Food Chem. 2018, 66, 4621– 4629.


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5. Cheng, J.; Wu, F. H.; Wang, P.; Ke, J. P.; Wan, X. C.; Qiu, M. H.; Bao, G. H. Flavoalkaloids with a pyrrolidinone ring from Chinese ancient cultivated tea Xi-Gui. J. Agric. Food Chem. 2018, 66, 7948– 7957. 6. Meng, Q.; Li, S.; Huang, J.; Wei, C. C.; Wan, X.; Sang, S.; Ho, C. T. Importance of the nucleophic property of tea polyphenols. J. Agric. Food Chem. 2019, Doi: 10.1021/acs.jafc.8b05917. 7. Yang, X.; Tomás-Barberán, F. A. Tea is a significant dietary source of ellagitannins and ellagic acid. J. Agric. Food Chem. 2019, Doi: 10.1021/acs.jafc.8b05010. 8. Hong, J.; Yang, L.; Zhang, D.; Shi, J. Plant metabolomics: an indispensable system biology tool for plant science. Int. J. Mol. Sci. 2016, 17, 767/1-767/16. 9. Wang, Y.; Kan, Z.; Thompson, H. J.; Ling, T.; Ho, C .T.; Li, D.; Wan, X. Impact of six typical processing methods on the chemical composition of tea leaves using a single Camellia sinensis cultivar, Longjing 43. J. Agric. Food Chem. 2019, Doi: 10.1021/acs.jafc.8b05140. 10. Guo, X.; Long, P.; Meng, Q.; Ho, C. T.; Zhang, L. An emerging strategy for evaluating the grades of Keemun black tea by combinatory liquid chromatography-Orbitrap mass spectrometry-based untargeted metabolomics and inhibition effects on α-glucosidase and αamylase. Food Chem. 2018, 246, 74-81. 11. Dai, W.; Tan, J.; Lu, M.; Zhu, Y.; Li, P.; Peng, Q.; Guo, L.; Zhang, Y.; Xie, D.; Hu, Z.; Lin, Z. Metabolomics investigation reveals that 8-C-N-ethyl-2-pyrrolidinone-substituted flavan-3ols are potential markers of stored white teas. J. Agric. Food Chem. 2018, 66, 7209-7218. 12. Zhou, J.; Wu, Y.; Long, P.; Ho, C. T.; Wang, Y.; Kan, Z.; Cao, L.; Zhang, L.; Wan, X. LCMS-based metabolomics reveals the chemical changes of polyphenols during high-



temperature roasting of large-leaf yellow tea. J. Agric. Food Chem. 2019, Doi: 10.1021/acs.jafc.8b05062. 13. Zhang, S.; Xuan, H.; Zhang, L.; Fu, S.; Wang, Y.; Yang, H.; Tai, Y.; Song, Y.; Zhang, J.; Ho, C. T.; Li, S.; Wan, X. TBC2health: a database of experimentally validated healthbeneficial effects of tea bioactive compounds. Brief. Bioinformatics 2017, 18(5), 830-836. 14. Yang, C. S.; Hong, J. Prevention of chronic diseases by tea: Possible mechanisms and human relevance. Annu. Rev. Nutr. 2013, 33, 161– 81. 15. Pan, M. H.; Lai, C. S., Wang, H.; Lo, C. Y.; Ho, C. T.; Li, S. Black tea in chemoprevention of cancer and other human diseases. Food Sci. Human Wellness 2013, 2(1), 13−22. 16. Yang, C. S.; Zhang, J. Studies on the prevention of cancer and cardiometabolic diseases by tea: Issues on mechanism, effective doses, and toxicities. J. Agric. Food Chem. 2019, Doi: 10.1021/acs.jafc.8b05242. 17. Chen, G.; Chen, R.; Chen, D.; Ye, H.; Hu, B.; Zeng, X.; Liu, Z. Tea polysaccharides as potential options for metabolic diseases. J. Agric. Food Chem. 2019, Doi: 10.1021/acs.jafc.8b05338.


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Introduction to the International Symposium on Chemistry, Flavor, and

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