Phenylpropanoidated Epicatechin Gallatess In Zijuan Green Tea

Tea is a natural,daily drink all over the world,offering a large number of health benefits.Green tea,a representative of non-fermented tea,is produced through steaming and drying the fresh leaves which stops the enzymatic oxidation,keeping the components more original to those of fresh leaves.i.e.9 it contains the largest amount of catechins.Catechins are considered as the most beneficial compounds in tea for human health due to the diversity of bioactivities,such as antioxidant properties,wound-healing effects,antihyperglycemic activity,and antihypertensive function.Zijuan tea is a characteristic variety in Yunnan province,China.The stem,bud,and leaf of Zijuan tea are purple ascribed to its rich in anthocyanins.Our group reported the isolation and identification of 22 compounds from Zijuan green tea including three phenylpropanoidated catechins with impressive acetylcholinesterase inhibitory activity.The neuroprotective effect of caffeoylated epicatechin(ECC)was further reported with the possible mechanism through interaction with neutrophil gelatinase-associated lipocalin.Inspired by the impressive activity of ECC,we continuingly studied the constituents of Zijuan green tea and discovered more phenylpropanoidated catechins.Phenylpropanoidated catechins are a distinctive class of secondary metabolites with the typical flavonoid skeleton substituted with a C6-C3 unit structure at the position C-6 or/and C-8 of the A ring or esterized with the 3-hydroxyl group at C ring.Four new phenylpropanoid-substituted flavan-3-ols were first isolated from the bark of Cinchona succirubra.From tea,two known together with other four new ones were reported from the famous dark tea,Pu-er tea.Although present literatures described phenylpropanoidated catechins,phenylpropanoidated catechin gallates have not been reported so far.In this study,we isolated and identified two pairs of isomerically new phenylpropanoidated epicatechin gallates(pECGs),named Zijuanins A-D(1-4),through repeated MCI,Sephadex LH-20,Toyopearl column chromatography(CC)and semi preparative high pressure liquid chromatography(HPLC).The four compounds chemical structures were elucidated on the basis of detailed spectroscopic analyses,including 1D and 2D NMR,HR-MS,IR and CD spectra.The human neuroblastoma cell line SH-SY5Y,subcloned from the SK-N-SH cell line,exhibits neuronal properties and is a classic in vitro model for screening neuroprotective agents used in Parkinson's or Alzheimer's disease(AD).AD is caused by mutifactors and oxidative stress is one of the leading causes.The famous anti-AD drug Huperzine A(hup A)and the major tea polyphenols esp.ester type tea catechins(ETC)have been reported to display neuroprotective effects against H2O2 induced injuries on the SH-SY5Y cells.In this paper,the isolated pECGs were assayed on the same cell line and compounds 1 and 2 showed promising protective effects.