Anti-Acetylcholinesterase Activity of Commercially Important Ceylon Black Tea (Camellia sinensis L.) Grades Belonging to Different Elevations: Potential Natural Product for Type 3 Diabetes Management?

Abstract

Aims: Sri Lankan tea which is known as the Ceylon tea is the world’s finest tea. Currently Sri Lanka remains as the second main black tea (BT) exporter and the main orthodox BT exporter in the world. Although several pharmacological activities of Ceylon tea have been reported, its anti-acetylcholinesterase (AChE) activity which has a direct relationship with the management of Alzheimer's disease or type 3 diabetes has not reported to date. Further, there are no comprehensive studies on anti-AChE activity of tea world over. Present study evaluated anti-AChE activity of commercially important Ceylon BT grades belonging to different elevations. Methodology: Freeze dried hot water extracts of Broken Orange Pekoe Fannings (BOPF), Orange Pekoe (OP) and Dust No.1 BT grades from low, mid and high grown elevations and a Ceylon green tea sample collected from the local market were studied for anti-AChE activity using 96 well micro plate-based assay (n=3 each). Results: Results showed that all tested Ceylon tea had anti-AChE activity with varying degrees of potentials in a dose dependent manner. The mean IC50 values of BOPF, OP and Dust No. 1 tea grades at different elevations varied from 499.61±10.95 - 569.19±5.78, 598.80±24.95 - 677.81±6.61 and 509.44±3.81 - 621.39±3.29 µg/mL respectively. Interestingly, observed anti-AChE activity of black tea showed significant differences (P< 0.05) among elevations. The order of potency of BOPF, OP and Dust No:1 BT for anti-AChE activity at different elevations was low grown>high grown=mid grown, high grown=low grown>mid grown and mid grown>low grown>high grown respectively. Anti-AChE activity of Ceylon green (433.96 ± 5.95 µg/mL) tea was significantly high (P<0.05) compared to the tested BT and activities of all Ceylon tea were moderate compared to the reference standard Galantamine (IC50:2.52±0.17 µg/mL). Conclusion: It is concluded that selected Ceylon BT grades had varying levels of anti-AChE activity and it varied with the elevations.