| Tea seeds and tea flowers contain a variety of bioactive ingredients, and can be used in the production of food, drink and cosmetic. Tea flowers possess many physiological functions and have been used in traditional medicines for deodorization, skin care, cough suppressant and expectorant in China. However, the lack of information about Tea flowers'possible toxicity restricts its application. The present investigation was carried out to evaluate the safety of tea flower extract by acute and genetic and subchronic toxicity studies. In the acute toxicity study, all animals gained weight and appeared active and normal, so the LD50 value must be>12.0 g/kg body weight. In the Ames test, micronucleus formation test and sperm abnormalities test, tea flower extract didn't have genotoxic potential. In the subchronic toxicity study, no dose-related effects on survival, growth, hematology, blood chemistry, organ weights, or pathologic lesions were observed.Theaflavins are a major group of polyphenol compounds in black tea and have strong antioxidant, anticancer and other bioactive properties. The inhibition effects of tea theaflavin (TF1), theaflavin-3-gallate (TF2A), theaflavin-3'-gallate (TF2B), theaflavin-3,3'-digallate (TF3) and epigallocatechin gal late (EGCG) on complex I, NDH-2, and ATP synthase from Escherichia coll were investigated. All the chemicals suppressed NADH-oxidase reactions catalyzed by complex I or NDH-2 on membrane vesicles. TF3 was the most potent inhibitor, and acted as a competitive inhibitor of complex I and a uncompetitive inhibitor of NDH-2 with respect to NADH. TF3 inhibited NADH-artificial acceptor(HAR) reductase activity, and was an uncompetitive inhibitor of complex I with respect to HAR. These results indicated that TF3 combined with more than one site on complex I. TF3 significantly decreased superoxide production by complex I, NDH-2 and cells, which was not contribute to the inhibition of the enzymes.Four theaflavin monomers and EGCG all inhibited ATP hydrolysis in both F1Fo membrane preparations as well as in isolated purified F,, but to different degrees. Compared with EGCG, theaflavin monomers had more effect on the inhibition of proton pumping by the membrane vesicle.Targets of Four theaflavin monomers and EGCG were searched on protein database by virtual screening based on molecular docking. Many new potent targets were found. These results were of big interest for further researches on the bioactivities of tea.A fast and efficient procedure was developed for the purification of two kaempferol glycosides from tea seed cake using supercritical fluid extraction (SFE). Conditions to obtain the highest total yield were determined to be an extraction time of 150 min, pressure of 20 MPa, temperature of 80℃, and 60% aqueous ethanol solution. Using the optimal conditions, the experimental yield was 11.4±0.4 mg/g, which was similar to the value predicted by the model. The glycosides of these two kaempferols identified by LC-MS were 3-0-[2-0-β-D-galactopyranosyl-6-0-α-L-rhamnopyranosyl]-β-D-glucopyranoside and 3-0-[2-0-β-D-xylopyranosyl-6-0-α-L-rhamnopyranosyl]-β-D-glucopyranoside. Moreover, compared with the conventional extraction method, SFE consumed less organic solvent and shorter time.However, the two kaempferol glycosides had no effects on the activities of complex I and ATP synthase from Escherichia coli in high concentration. More works on their bioactivities are needed. |
PDF Full Text Request