Epigallocatechin gallate (EGCG), epicatechin gallate (ECG), caffeine, and theanine are the four major chemical constituents in tea. Currently, we are separating and identifying novel compounds derived from EGCG, ECG, caffeine, and theanine, including hydroxycinnamoylated catechins (HCCs), flavoalkaloids, and imidazole alkaloids. Here, we first summarized the isolation, identification, biosynthetic pathway (Figure 1A), and neuroprotection through inhibiting both AChE (Figure 1B) and NGAL (Figure 1C & D) of (-)-epicatechin 3-O-caffeoate (ECC) from Zijuan green tea, suggesting that ECC could be a multi-target agent against ageing-related diseases, and hopefully be developed as a primary prevention agent intervening related diseases at an earlier stage. Besides, four flavoalkaloids was isolated from commercial white tea and also detected in fresh tea leaves, suggesting that flavoakaloids in tea may be the products from the interaction between the most abundant metabolites EGCG or ECG, and L-theanine in tea plant through deamination, decarboxylation of L-theanine into N-ethyl-pyrrolidinone, followed by coupling of the product and EGCG (Figure 2).

Progress in tea chemistry from natural products approach

256th National Meeting (2018)

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