Study on Biochemical Components of Pu-erh Raw Tea and Its Antioxidant Activity in Animal

Abstract

【Objective】The differences of biochemical components of Pu-erh raw tea stored at different times and its antioxidant activity in aged mice were determined and compared.【Method】The contents of water extraction, tea polyphenols, catechins, amino acids, caffeine, flavonoids and soluble sugar of Pu-erh raw tea stored at different years(in 2014 and 2020) were determined. Moreover, the effects of Pu-erh raw tea stored at different times on body weight, water consumption, food intake, liver index, kidney index, spleen index, activities of glutamic-pyruvic transaminase (ALT), glutamic oxalacetic transaminase (AST) and superoxide dismutase (SOD), and contents of glutathione (GSH) and malondialdehyde (MDA) in serum and liver of aged mice were determined.【Result】The contents of water extraction (40.11%), amino acids (3.15%), caffeine (4.18%), GC (0.21%), EGC (0.84%), C (0.61%), EC (2.46%), EGCG (6.90%), CG (0.10%), non-ester catechins (4.11%), ester-catechins (13.44%) and total catechins (17.55%) decreased notably in Pu-erh raw tea with longer storage time, while the content of gallic acid (0.38%) increased significantly. Pu-erh raw tea with longer storage time significantly reduced the activity of AST in the serum (21.49 U/L) but improved the content of GSH (77.28 μmol/gprot) and the activity of SOD in the liver of aged mice; In addition, it reduced the activity of AST and the content of MDA in the liver of aged mice, but the levels were not significant. Pu-erh raw tea with shorter storage time significantly reduced the activity of AST in the serum (29.50 U/L) of aged mice, improved the activity of SOD and GSH content, reduced the activities of ALT and AST and the MDA contents of liver and serum, but the levels were not significant.【Conclusion】As the increase of storage time, the contents of water extraction, amino acids, caffeine and catechins decreased notably, while gallic acid increased significantly. Pu-erh raw tea stored at different times both have antioxidant effect on the aged mice. Besides, Pu-erh raw tea with longer storage time had better ability to enhance the activity of antioxidant enzymes SOD and GSH in vivo.

Keywords

• pu-erh tea
• raw tea
• storage time
• biochemical component
• aged mice
• antioxidant activity