Determination of free amino acids in tea by a novel method of reversed-phase high performance liquid chromatography applying 6-Aminoquinolyl-N-Hydroxysuccinimidyl carbamate reagent

Li, Min; Li, Daxiang; Tai, Yuling; Gu, Chao; Song, Yasai; Jiao, Weiting; Ning, Jingming; Wei, Chaoling; Gu, Xungang; Ho, Chi‐Tang; Hajano, Jamal U Ddin; Wan, Xiaochun

doi:10.1007/s13197-018-3366-9

Cited by 18 publications

(17 citation statements)

References 32 publications

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“…Free amino acids analysis. The determination of free amino acids in tea plant roots was performed as described 64,65 with minor modifications. Briefly, a HPLC system (Waters 2695) coupled to a fluorescence detector (Waters 2475) and an ultraviolet-visible detector (Waters 2489) was used in this study.…”

Section: Methodsmentioning

confidence: 99%

Transcriptional regulation of amino acid metabolism in response to nitrogen deficiency and nitrogen forms in tea plant root (Camellia sinensis L.)

Yang

Tai

et al. 2020

Sci Rep

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Free amino acids, including theanine, glutamine and glutamate, contribute greatly to the pleasant taste and multiple health benefits of tea. Amino acids in tea plants are mainly synthesized in roots and transported to new shoots, which are significantly affected by nitrogen (N) level and forms. However, the regulatory amino acid metabolism genes have not been systemically identified in tea plants. Here, we investigated the dynamic changes of free amino acid contents in response to N deficiency and forms in tea plant roots, and systemically identified the genes associated amino acid contents in individual metabolism pathways. Our results showed that glutamate-derived amino acids are the most dynamic in response to various forms of N and N deficiency. We then performed transcriptomic analyses of roots treated with N deficiency and various forms of N, and differentially expressed amino acid metabolic genes in each pathway were identified. The analyses on expression patterns and transcriptional responses of metabolic genes to N treatments provided novel insights for the molecular basis of high accumulation of theanine in tea plant root. These analyses also identified potential regulatory genes in dynamic amino acid metabolism in tea plant root. Furthermore, our findings indicated that the dynamic expression levels of CsGDH, CsAlaDC, CsAspAT, CsSDH, CsPAL, CsSHMT were highly correlated with changes of amino acid contents in their corresponding pathways. Herein, this study provides comprehensive insights into transcriptional regulation of amino acid metabolism in response to nitrogen deficiency and nitrogen forms in tea plant root.(Ser), glycine (Gly) and cysteine (Cys) synthesis. In tea plant, Thea is synthesized from Glu and ethylamine (EA) by theanine synthetase (TS) 14 . EA is likely produced from alanine under the catalysis of alanine decarboxylase 15 .Amino acid catabolism have been clearly described in animals, however, limited information of amino acid catabolism is available in plants. Hildebrandt et al. summarized the catabolic pathways of amino acids in land plants. Generally, amino acids are catabolized by oxidative deamination, oxidative decarboxylation, and transamination. These reactions are catalyzed by amino acid dehydrolases, decarboxylases and aminotransferases, respectively. Gln, Asn and Arg are also hydrolyzed by asparaginase, glutaminase, and arginase to release amide groups 16 .The accumulation of free amino acids is resultant of biosynthesis and catabolism. Previous studies showed that feedback inhibition loops control amino acid biosynthesis in plants 17 . Here, the accumulation of an amino acid inhibits the transcription or the activities of the enzymes in its biosynthesis pathway [18][19][20] . Expression of feedback-insensitive form of enzymes resulted in higher levels of the corresponding amino acids 17,21 . The central role of amino acid catabolism is to adjust the amino acid pool size, especially under stress conditions 12 . Some regulatory enzymes in amino acid metabolism have been ident...

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Section: Methodsmentioning

confidence: 99%

Transcriptional regulation of amino acid metabolism in response to nitrogen deficiency and nitrogen forms in tea plant root (Camellia sinensis L.)

Yang

Tai

et al. 2020

Sci Rep

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“…The results indicated that LOT contained higher water extract and total free amino acid concentrations and lower total tea polyphenol and crude fiber concentrations than LST for the same plucking. LST had fewer free amino acids, which may be related to the coarse leaves and stems (Li et al., 2018). These findings were consistent with our assumption.…”

Section: Resultsmentioning

confidence: 99%

Effects of stem removal on physicochemical properties and sensory quality of tencha beverages (Camellia sinensis; Chuanxiaoye)

Xiao

Meng

Liu

2021

Journal of Food Science

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Fresh tea leaves (Camellia sinensis; Chuanxiaoye) used to make tencha tea are a combination of the stem and leaf. Tencha made from the leaf alone is considered a high‐quality tencha beverage with a seaweed‐like aroma, mellow taste, and a green appearance. However, no study has investigated the differences between these two variants. In this study, the effects of stem removal on physicochemical properties and sensory quality of tencha beverage were investigated. The appearance feature, taste, and aroma were evaluated, and the results indicated that stem removal improved the quality of tencha beverages. The water extract, total free amino acids, total catechin, epigallocatechin gallate, caffeine, and chlorophyll were higher in leaf‐only tencha (LOT) than in leaf and stem tencha (LST), whereas the crude fiber and phenol ammonia ratios were lower in LOT than in LST. Principal component analysis and hierarchical clustering analysis further discriminated between the tencha beverages with different stem contents. This study provided a theoretical basis for quality control by adopting a stem–leaf separation process in tencha manufacturing.Practical ApplicationThis research provides theoretical guidance for improving tencha quality during manufacturing.

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“…The proposed method was further validated using a reported HPLC−UV quantification method for Ltheanine. 37 HPLC was performed on an Agilent 1100 Series system (Agilent Technologies, Inc., Pickerington, OH) equipped with an AccQ-Tag C18 amino acid analysis column (150 mm × 3.9 mm i.d. × 4-μm pore size, Waters Co. Ltd., Milford, MA) under the wavelength of 254 nm.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…The derivatization was performed according to the method described by Li. 37 The mobile phase was isocratic and composed of 60% acetonitrile in ultrapure water with 10% AccQ-Tag Eluent A at pH 5.7 (Waters Co. Ltd., Milford, MA) to facilitate separation and detection of amino acids. The mobile phase flow rate was constant at 1.0 mL/min.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Development and Application of a Fast Gas Chromatographic Method Offer New Insights into l-theanine Production Regulation in Camellia sinensis L.

Liu

Ferreira

Xiao

et al. 2021

J. Agric. Food Chem.

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Tea is the most consumed beverage worldwide, and l-theanine in tea leaves significantly affects their flavor and market quality. We have developed and validated a fast and reliable gas chromatographic method with flame ionization detection (GC-FID) to quantify l-theanine after its extraction from Camellia sinensis (tea plant) and derivatization. The procedure was completed in 40 min, from extraction to chromatographic analysis, with a recovery rate of more than 93% and allowing a high sample throughput. The GC-FID intraday precision was within 0.57–2.28%, while the interday precision ranged from 1.57 to 13.48%. The intraday accuracy ranged from −6.84 to 5.26%, while the interday accuracy ranged from −1.08 to 3.12%. The limit of detection was 2.28 μg/mL, and the limit of quantification was 6.47 μg/mL. The GC-FID method was validated by high-performance liquid chromatography with UV detection (HPLC–UV) and was used to investigate the biosynthesis and regulation of l-theanine in tea plants. We found that plants fed with ethylamine significantly increased l-theanine concentrations in roots, while exogenous supplementation of glutamic acid, carbamide, and glutamine did not significantly affect the l-theanine level in roots. Our results also indicated that roots were not indispensable for the biosynthesis of l-theanine, which was detected in undifferentiated embryonic calluses in concentrations (g/100 g dry weight) as high as in leaves of whole plants (1.67 and 1.57%, respectively) and without any exogenous theanine precursor supplementation.

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Determination of free amino acids in tea by a novel method of reversed-phase high performance liquid chromatography applying 6-Aminoquinolyl-N-Hydroxysuccinimidyl carbamate reagent

Cited by 18 publications

References 32 publications

Transcriptional regulation of amino acid metabolism in response to nitrogen deficiency and nitrogen forms in tea plant root (Camellia sinensis L.)

Transcriptional regulation of amino acid metabolism in response to nitrogen deficiency and nitrogen forms in tea plant root (Camellia sinensis L.)

Effects of stem removal on physicochemical properties and sensory quality of tencha beverages (Camellia sinensis; Chuanxiaoye)

Development and Application of a Fast Gas Chromatographic Method Offer New Insights into l-theanine Production Regulation in Camellia sinensis L.

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