Study On The Functionality Of Polyphenols In Zijuan Tea

Nowadays,chronic diseases are serious threat to human health.Common metabolic syndromes such as hypertension,hyperglycemic and obesity are spreading across the world.China has a high incidence of these diseases,not only the large number of people,but also it has become younger in average age.Many studies have demonstrated that some natural products have a preventive or therapeutic effect on hypertension,hyperglycemic and obesity,and tea is one of them.Zijuan tea,Camellia sinensis var.assamica,which is rich in polyphenol components,especially catechins and anthocyanins,has been much attentioned by its functionality.At present,there are few reports about the anti-hypertensive,anti-hyperglycemic and anti-obesity activities of Zijuan tea.The purpose of this study was to investigate whether the extracts of Zijuan tea can inhibit the key enzymes of hypertension,hyperglycemic and obesity,and then try to explore whether it has the potential to anti-hypertensive,anti-hyperglycemic and anti-obesity.The main research contents were as follows:1.The identification and quantification of catechins in the crude extracts of Zijuan tea were carried out.The crude polyphenol fraction?defined as ZTE₁?was extracted from Zijuan tea by using Amberlite XAD-7HP adsorption column chromatography after immersed in acidified methanol.ZTE₁ was then separated to the precipitated?defined as ZTE₂?and the soluble?defined as ZTE₃?with ethyl acetate.The identification and quantification of catechins were conducted by high performance liquid chromatography?HPLC?analysis and published data.The results showed that,the amounts of catechins in three crude fractions were respectively 208.25 ± 4.66?46.02 ± 3.19?336.66±14.70 mg/g.2.The inhibitory activities of the three crude fractions and two anthocyanins——delphinidin-3-O-?-D-?6-?E?-p-coumaroyl?galactopyranoside?AN₃?and cyanidin-3-O-?-D-?6-?E?-p-coumaroyl?galactopyranoside?AN₄?towards angiotensin converting enzyme?ACE?,?-amylase and pancreatic lipase were evaluated comparing with epigallocatechin gallate?EGCG?.The results showed that,all the Zijuan tea extracts have inhibitory activities towards the three enzymes.The inhibitory activities of ZTE₃ towards the three enzymes,ZTE₁ and ZTE₂ towards a-amylase,ZTE₁ towards pancreatic lipase were stronger than EGCG.And the inhibitory activity of AN₃ towards ?-amylase has no significant difference with EGCG.Furthermore,ZTE₃ had the highest inhibitory acitivity against ACE,whereas ZTE₂ and ZTE₁ had the highest inhibitory acitivity against a-amylase and pancreatic lipase,respectively.The inhibitory activity of AN₃ was higher than AN₄ towards all the three enzymes.3.The inhibitory type of AN₃ and AN₄ towards ACE,a-amylase and pancreatic lipase was explored.The results showed that,AN₃ and AN₄ were noncompetitive inhibitors of ACE,a-amylase and pancreatic lipase with Ki values of 0.33,0.37 mg/mL;0.39,0.41 mg/mL and 0.22,0.78 mg/mL.