Study On Liver Protection Effect Of Huoshan Large-leaf Yellow Tea Based On PRMT5^?Hep Mice Model

The large-leaf yellow tea is one of the six major tea species,own two special processes,called "sealed yellowing" and "high fire baking" during manufacture.So the yellow tea soup tastes heavy and mellow,among which alkaloids and polyphenols are rich.Our previous researches proved that large-leaf yellow tea had good effect in lowering blood glucose and lipid,and improving metabolic syndrome.However,the mechanism of liver protection effect has not been deeply explored.Protein arginine methyltransferase 5(PRMT5)participates in various biological processes through the methylation modification of the protein.Mice with the PRMT5 knockout in whole-body were found fetal-death.Our team has bred liver-specific PRMT5 knockout mice(PRMT5?Hep)which develops liver fibrosis during adolescence,then develops into hepatocellular carcinoma at old age.Therefore,this study firstly analyzed the chemical quality and infrared spectrum characteristics of large-leaf yellow tea from Huoshan,and compared chemical quality difference between 7 kinds of tea sample.Then using PRMT5?Hep mice as the model,the effects of large-leaf yellow tea intervention on liver function were studied.The results are as follows:1.Among 7 kinds tested samples,green tea(28.12±0.08mg/g,24.81 ±0.29 mg/g)had the highest total polyphenol content,followed by white tea(22.16±0.38mg/g)and large-leaf yellow tea(20.81±0.04 mg/g,16.79 ±0.43mg/g).The content of tea polysaccharides are the highest in two kinds of large-leaf yellow tea(1.93 ±0.14 mg/g,1.99 ±0.11 mg/g).The total amino acid content was higher in green tea(17.17±0.05 mg/g,18.81 ±0.06 mg/g)and white tea(17.07±0.11 mg/g),and lower in large-leaf yellow tea(3.05±0.01 mg/g,1.56±0.04 mg/g)which only higher than that in whole fermented dark tea.The content of catechins was the highest in two kinds of green tea,followed by large-leaf yellow tea.Alkaloid content was relatively stable in 7 kinds of tea sample.2.Near infrared spectroscopy was used to cluster tea leaf and tea soup.The PLS method was used to construct the quantitative model of total tea polyphenols,tea polysaccharides,soluble sugars and five tea monomers,with the R2 values ranged from 0.95 to 0.71 which means the good quantitative analysis results.3.A total of 55 mice were bred and selected,which are genotype-matched mice and their littermate control.These mice were divided into four groups as follow:Con(WT),ConP5(PRMT5?HeP),YT(WT+5%large-leaf yellow tea),and YTP5(PRMT5?Hep+5%large-leaf yellow tea).The body weight,food and water intake of the mice were monitored weekly,and the mice were sacrificed at 26 or 61 weeks after treated,respectively.The index of mice were detected,such as growth performance,liver function and tissue morphology.4.After dietary intervention with large-leaf yellow tea for 26 weeks,the body weight of male mice in ConP5 group and YT group were significantly lower than the Con group.The body weight of YTP5 group mice was significantly lower than ConP5 group.The tea treatment increased the drinking water of PRMT5?Hep mice without affecting their food intake.The liver surface of ConP5 group mice were rough and uneven,and it's liver/weight ratio was significantly higher than that of Con.Some cracks were observed in ConP5 liver tissue through microscopic observation.After tea intervention,the liver surface recovered smoothly and the liver/weight ratio decreased significantly compared to ConP5 group.There were no significant differences in serum index,such as TG,TC,AST and ALT between the four groups of mice.5.There were no significant difference in body weight,liver weight and liver/weight ratio between the four groups of mice after 61 weeks tea treatment.The liver surface morphology was normal both in Con and YT group.In the ConP5 group,white lumps appeared on the liver surface,which become hypertrophic at the edge of liver lobe.Meanwhile the number of lumps in ConP5 group increased significantly compared with Con group.After treatment with tea,the number of lumps reduced 37%significantly,showing that tea could inhibit the formation of liver tumors significantly.In summary,among the seven tea samples we tested,large-leaf yellow tea had the highest polysaccharide content,it's total tea polyphenol content was lower than green and white tea,it's total amino acid content was low,and the content of catechins and alkaloids was intermediate between fermented tea and non-fermented tea.The dietary intervention of large-leaf yellow tea in PRMT5?Hep mice showed significantly decreased number of lumps in liver surface and improved tissue morphology,which proved effect of protecting liver function by tea.