Medicinal Value of Camellia sinensis Bioactive Components: Focus on Theaflavins and Tea Polysaccharides

Tea, derived from the leaves of Camellia sinensis, is a non-alcoholic beverage rich in pharmacologically active bioactive components. This plant contains many bioactive components, such as xanthine alkaloids, tea polyphenols, L-theanine, theaflavins, tea polysaccharides, and volatile oils. Evidence indicates that these bioactive constituents contribute to various physiological benefits, including body weight regulation, anti-fatigue properties, hypoglycemic action, antitumor and neuroprotective potentials, improvement of vascular function, and attenuation of airway-induced organ obstruction. Up to now, research has systematically confirmed and summarized the functions of xanthine alkaloids, tea polyphenols, and L-theanine. However, much less attention has been given to theaflavins and tea polysaccharides. This review therefore focuses on how theaflavins and tea polysaccharides work in the human body and what they do, as well as how these two types of compounds are metabolized in tea plants. Overall, this work provides a new perspective on the study of bioactive components in tea and builds a useful foundation for a deeper understanding of how these components act in the human body.