Abstract
Phenolic compounds in tea plant [Camellia sinensis (L.)] play a crucial role in dominating tea flavor and possess a number of key pharmacological benefits on human health. The present research aimed to study the profile of tissue-specific, development-dependent accumulation pattern of phenolic compounds in tea plant. A total of 50 phenolic compounds were identified qualitatively using liquid chromatography in tandem mass spectrometry technology. Of which 29 phenolic compounds were quantified based on their fragmentation behaviors. Most of the phenolic compounds were higher in the younger leaves than that in the stem and root, whereas the total amount of proanthocyanidins were unexpectedly higher in the root. The expression patterns of 63 structural and regulator genes involved in the shikimic acid, phenylpropanoid, and flavonoid pathways were analyzed by quantitative real-time polymerase chain reaction and cluster analysis. Based on the similarity of their expression patterns, the genes were classified into two main groups: C1 and C2; and the genes in group C1 had high relative expression level in the root or low in the bud and leaves. The expression patterns of genes in C2-2-1 and C2-2-2-1 groups were probably responsible for the development-dependent accumulation of phenolic compounds in the leaves. Enzymatic analysis suggested that the accumulation of catechins was influenced simultaneously by catabolism and anabolism. Further research is recommended to know the expression patterns of various genes and the reason for the variation in contents of different compounds in different growth stages and also in different organs.
Highlights
Tea is one of the three popular nonalcoholic beverages consumed throughout the world
Phenolic compounds in tea plant were analyzed qualitatively by liquid chromatography (LC)-time of flight (TOF)-mass spectrometer (MS) and ultra performance liquid chromatography (UPLC)-QQQ-MS/MS, and they were identified (Table 1, Figs. 2 and 3) based on the data obtained from the standard substances or published literature including tR, lmax, ([M+H]+/[M–H]2), and major fragment ions [17,41,42,43,44]
Nine phenolic acids among the 50 phenolic compounds consisted of hydroxybenzoic acid (HBA) and hydroxycinnamic acid (HCA) derivatives, and they were identified by direct comparison of data with authentic standards (Table 1, Figs. 2 and 3, Fig. S1) and literature [17]
Summary
Tea is one of the three popular nonalcoholic beverages consumed throughout the world. Phenolic compounds are the main flavor components and functional ingredients in tea, which possess key pharmacological activities such as antioxidant, antimutagenic, anticarcinogenic, antidiabetic, antibacterial, anti-inflammatory, antihypertensive, anticardiovascular disease, solar UV protection, body weight control, and therapeutic properties in Parkinson’s disease [15]. An important secondary metabolite in tea, account for 18% to 36% dry weight in the fresh leaves and tender stem. More than 96 phenolic compounds have been identified from 41 green teas and 25 fermented teas, which included the following: 28 acylated glycosylated flavonols, 19 Oglycosylated flavonols, 15 phenolic acid derivatives, 12 catechins, 7 C-glycosylated flavones, 6 PAs, and 3 flavonols [17]. The methylated catechins have been identified in fresh leaves and other tea products [18]
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