Evaluation of In-Vitro Anticoagulant Activity of Sri Lankan Black Tea (Camellia sinensis) and The Effect of Tea Polysaccharides on Blood Coagulation Process

Warfarin and Heparin are extensively used clinically to prolong blood clotting to treat thrombotic diseases. However, they have side effects such as bleeding and thrombocytopenia. Because of these side effects, there has been a continuous search for alternative anticoagulant therapies that can offer efficacy without the same level of risk. The goal is to find anticoagulant therapies that strike a balance between effectively preventing blood clots while minimizing the risk of bleeding complications or other side effects commonly associated with traditional anticoagulants. Nature offers a wealth of compounds that have demonstrated various therapeutic benefits, and investigating natural sources for their anticoagulant potential could yield promising results. Hence, this study examined various Sri Lankan black tea (SBT) for anticoagulant potential by monitoring whole blood clotting, activated-partial-thromboplastin-time (aPTT), prothrombin-time (PT), and antiplatelet activity. Hot water extract, caffeine rich and poor, polysaccharide rich (PR) and poor extracts of tea were prepared following the literature procedures. Ca2+ induced whole blood clotting time of the extracts were evaluated using citrated arterial goat blood. Polysaccharide rich (PR) extract obtained from low-grown tea showed the highest anticoagulant activity (270 ± 7 s) when compared to the polysaccharide low extract (136 ± 2 s) with the negative control (100 ± 3 s). Polysaccharides have a close relationship with blood coagulation and heparin which is widely used as an anticoagulant is also a polysaccharide. The results showed that PR prolonged aPTT and PT significantly. Platelet aggregation assay indicated that PR has aspirin like antiplatelet behavior as well. Collectively, our results suggest that SBT, specifically PR, possesses antithrombotic activities and that the current study could provide information for the development of new anticoagulants based on tea polysaccharides.