## 4 Discussion  
At this point in time, more than two-thirds of the world's population consumes tea. Tea trees native to the Bayu region of southern China were first used as a medicinal beverage in China. According to different processing methods, tea can be divided into non-fermented (such as green tea), semi-fermented (such as oolong tea), and full-fermented teas (such as black tea), and their bioactive ingredients are quite different. The active ingredients in tea mainly include polyphenols, flavonoids, amino acids, vitamins, and other compounds [20]. WST belongs to the non-camella tea group, and the young leaves used to make WST are rich in polyphenols, flavonoids, amino acids, vitamins, and trace mineral elements. These compounds have many pharmacological effects, including anti-bacterial, anti-inflammatory, anti-hypoxia, anti-fatigue, hypoglycemic, hypolipidemic, and physique enhancement [4]. Tea polyphenols are chemopreverative agents against malignant tumors and have strong free radical scavenging and reducing activities. These compounds capture and detoxify the free radicals of various promoters of carcinogenesis as well as the free radicals produced by exposure to radiation and light. These compounds also inhibit the production of nitroso compounds, which possess potent carcinogenic activities, by reducing bisulfite in the digestive organs. Because tea polyphenols inactivate enzymes and inhibit viral activity, they are effective against the carcinogenic effects of certain viruses [21]. Isoquercitrin, a flavonoid glycoside compound that is readily soluble in organic solvents, has anti-inflammatory, anti-oxidant, anti-viral, anti-tumor, anti-atherosclerotic, neuroprotective, blood pressure lowering, and other biological activities [22]. Quercitrin is widely found in plants, and studies have shown that quercetin can lower blood fat and blood sugar and has anti-oxidation and anti-virus effects [23]. Quercetin has been shown to be an inhibitor of cancer in  
Figure 7: Analysis of the constituents of WST extracts via HPLC assay. (**A**): WST chromatogram; (**B**): standard chromatograms. many tissues, including the colon, lungs, and intestines [24]. Taxifolin has remarkable effects, including anti-tumor, anti-inflammatory, and anti-radiation, and is non-toxic, non-teratogenic, and non-mutating, but it is difficult to dissolve in water, resulting in a low bioavailability [25]. Myricetin can inhibit the proliferation and migration of many types of tumor cells [26], and the pharmacological effects of Baialin include anti-atherosclerosis, protection against myocardial ischemia-reperfusion injury, protection of cardiomyocytes and endothelial cells, inhibition of myocardial remodeling, and other properties [27]. Neohesperidin dihydrochalcone, a flavonoid derivative (vitamin P), has the effect of protecting the liver and inhibiting gastric acid secretion [28]. Others, such as chlorogenic acid, p-coumaric acid, and rosmarinic acid, also have significant pharmacological effects regarding immune regulation, inhibition of tumors, and prevention of cardiovascular diseases [29; 30; 31]. Similar to many other studies on tea, the presence of these bioactive chemicals in WST extracts may be the main cause of their biological activities. The oxidation phenomenon caused by free radicals is the main inducement of aging in the human body [32]. In order to protect the body from free radical damage, more and more antioxidant substances have been investigated and applied, but to evaluate the level of antioxidant activity of any compound requires an accurate and scientific method. Compared with in vivo antioxidant evaluation methods, the in vitro antioxidant evaluation method is widely used because of its rapidity and convenience. DPPH is a stable free radical with a single electron that accepts an electron or hydrogen radical and becomes a stable yellow diamagnetic molecule. The reaction mechanism between antioxidants and DPPH depends on the structural conformation of the antioxidants.