Green tea is rich in colorless, bitter, but non-astringent phenols called catechins. During the production of black tea, enzymes that are released during the process of crushing the tea leaves and the oxidation process convert most of the catechins and theaflavins, which give black tea a slightly more bitter and astringent taste. Tea also contains caffeine, theanine, flavonoids, saponin, vitamins and minerals. 
Catechin: is the most common phenolic flavonoids in green tea, with anti-carcinogenic properties
Vitamins: green tea contains vitamins C and B2, along with acid folic and water-insoluble vitamin E
Minerals: tea is rich in Potassium, Calcium, Phosphorus, Magnesium, and other trace minerals
Flavonoids: Polyphenol Flavonoids are believed to have antioxidant and immune-boosting properties
Saponin: is foaming and antibacterial agents that help reduce blood pressure and prevent decay
Xanthine derivatives: caffeine and other xanthine derivatives, such as theobromine are stimulants
Theanine: Amino acid that supports stress relief with a strong Umami and sweet flavor
