Effect of Extracts and Components of Black Tea on the Activity of β- Glucuronidase, Lipase, α-Amylase, α-Glucosidase: An in vitro Study

The objective of the present study was to determine the inhibitory properties of the infusions and decoctions of four samples of Indian black tea (BT) and some of the tea flavonoids, gallic acid and caffeine, in vitro, against β- glucuronidase, lipase,α-amylase and α-glucosidase. These enzymes are related to liver disorders, obesity and diabetes. The phenolic constituents and caffeine content in the BT extracts were measured quantitatively by HPLC. It was noted that both infusion and decoction of BT had β-glucuronidase inhibitory property close to that of silymarin. Epigallocatechin gallate, epicatechin, and gallocatechin showed higher β-glucuronidase inhibitory activity than that of BT extracts and silymarin. BT extracts also inhibited the enzyme lipase. Thearubigin, theaflavin, epigallocatechin gallate, epicatechin and gallocatechin showed significant lipase inhibitory properties that were superior to the drug orlistat. The tea extracts, flavonoids and gallic acid inhibited the activity of α-amylase and α-glucosidase. Theaflavin and catechin had α-amylase inhibitory activity better than that of acarbose. This in vitro study reveals that BT extract and the phenolic components may have potential benefit for controlling liver disorders, obesity and diabetes. Keywords: α-amylase, α-glucosidase, β-glucuronidase, black tea, flavonoids, gallic acid, lipase.