Diverse inhibition of plasminogen activator inhibitor type 1 by theaflavins of black tea

Fruits, vegetables, spices and a variety of teas are suggested for the prevention of many diseases. They encompass active, non-nutritional ingredients called nutraceuticals which are defined as food products that provide health benefits. Many nutraceuticals have been tested to identify inhibitors of plasminogen activator inhibitor (PAI-1). PAI-1 is the major and fast acting physiological inhibitor of fibrinolysis. However, preclinical studies of PAI-1 inhibitors have revealed an additional role of PAI-1 in the pathogenesis of vascular remodeling, renal injury, diabetes, obesity, Alzheimer's disease and cancer. Thus PAI-1 is a potential therapeutic target in some of these diseases. Our previous study revealed that a black tea extract (containing mostly theaflavins) inhibits PAI-1. In this study we report results for four pure (>98%) theaflavins. Inactivation of PAI-1 was tested by clot formation and by its lysis using thromboelastometry and measurements of human plasma turbidity. Among four tested theaflavins, theaflavin-3'-gallate was the most potent in PAI-1 inhibition trailed by theaflavin-3,3'-digallate, while the other two i.e., theaflavin and theaflavin-3-gallate did not show inhibitory activity.