Antioxidant, antihypertensive, and anticancer activities of the flavonoid fractions from green, oolong, and black tea infusion waste

The flavonoid fractions from green (GTF), oolong (OTF) and black tea (BTF) infusion waste were comparatively studied on the antioxidant, antihypertensive and anticancer activities. HPLC-MS method was used to analyze the compositions of the flavonoid fractions. BTF exhibited the highest anti-hypertension effect and anticancer activities. Quercetin-3-O-rutinoside (QR) was highly related to angiotensin I-converting enzyme (ACE) inhibitory effect (r = 1.000), and BTF exhibited the highest ACE inhibitory effect with the IC50 value of 46.72 µg/mL. BTF administration resulted in systolic decrease of 57.08 mmHg at 8 hr which was even higher than captopril (p < 0.05). The IC50 value of BTF on the growth of SMMC7721 cells was 52.31 µg/mL. Quercetin-3-O-rutinoside, kaempferol 3-O-rutinoside, kaempferol 3-O-glucoside and patuletin O-glucoside might be the effective constituents in BTF by the principal components analysis. BTF might be good nutrition supplements in the treatment of hypertension and hepatocellular carcinoma. Practical applications Tea is a kind of healthy and lowest cost beverages globally. It is generally consumed in three forms including green tea, oolong tea and black tea. Flavonoids can lower the blood pressure and inhibit the cancer cells growth due to their antioxidant activities. The flavonoids could produce undisputed antihypertensive effects and had the ability of preventing cancer that induced by oxidative stress. In addition, the flavonoids could be used as potential anticancer agent through inducing apoptosis and metastasis of the tumor cells. The relationships between the components of the flavonoids with antihypertensive and anticancer activities were comparatively investigated. The research could provide a new nutrition supplements in the treatment of hypertension and hepatocellular carcinoma.