Antioxidant, Anti-inflammatory, And Anti-cancer Activities Of Six Types Of Tea

Abstract:According to the processing technology and quality characteristics,tea[Camellia sinensis?L?.O.Kuntze]can be categorised into six types:green tea,white tea,yellow tea,oolong tea,dark tea,black tea,and difference in chemical compositions or functional properties maybe observed among them.This study aimed to analyze the chemical compositions of water extract of Fuding Dabai?white tea?,Junshanyinzhen?yellow tea?,Jinguanyin?oolong tea?,Yunnan Daye?green tea,black tea,and dark tea?,and further investigate their antioxidant,anti-inflammatory,and anti-cancer activities in vitro.Antioxidant capacitywas determined using three c hemical assays and cellular antioxidant activity assay;Anti-inflammatory propertywas assessed by nitric oxide?NO?-scavenging assay and lipopolysaccharide?LPS?-induced RAW264.7 cells model;Anti-cancer activity was evaluated using human colon cancer cell line HCT116,human liver cancer cell line HepG2,and human breast cancer cell line MDA-MB-231.Moreover,white tea-induced apoptosis in HCT116 cells was measured by Annexin V-fluorescein isothiocyanate?FITC?/propidium iodide?PI?double staining assay.Finally,the expression level of apoptosis-related proteins in white tea-induced HCT116 cells was analyzed bywestern blot,and the underlying mechanism of apoptosis induction was preliminarilyexplored.The main results were listed as follows:1.Antioxidant activity of six types of teaThe results with regard to antioxidant activity of six types of tea from different antioxidant methods were showed.For both 2,2-diphenyl-1-picrylhydrazyl?DPPH?and2,2?-azino-bis?3-ethylbenzthiazoline-6-sulfonic acid??ABTS?radical assays:green tea,white tea,yellow tea,oolong tea>dark tea>black tea;For ferric reducing antioxidant power?FRAP?assay:green tea,white tea,yellow tea,oolong tea>dark tea>black tea;For cellular antioxidant activity?CAA?assay:white tea>green tea,oolong tea,yellow tea>dark tea>black tea.Both chemical and cell-based antioxidant assays indicated that fermentationprocess reduced antioxidant activity in the manufacturing of tea,although the antioxidant capacity of six types of tea measured by different mothods was not consistent.2.Anti-inflammatory activity of six types of tea?1?The half inhibitory concentration(IC₅₀)values for NO-scavenging effect of six types of tea ranged from 99.27 to 214.68?g/mL.Among six types of tea,green,white,and yellow tea showed better NO-scavenging capacity with IC₅₀ values ranging from 99.27 to104.83?g/mL and no significant difference was observed between them?P<0.05?.Moreover,the IC₅₀ values for NO-suppressing effect of six types of tea ranged from 398.13to 951.27?g/mL in lipopolysaccharide?LPS?-induced RAW264.7 cells,and yellow tea exhibited the strongest inhibition on NO production.In addition,compar ing with other five types of tea,yellow tea also exhibited the highest inhibitory activity against tumor necrosis factor-??TNF-??and interleukin-6?IL-6?production,and the inhibition rate for TNF-?and IL-6 reached 69.25%and 87.68%,respectively,at a concentration of 500?g/mL.?2?Comparing with the LPS group,yellow tea extract?125,250,and 500?g/mL?significantly decreased inducible nitric oxide synthase?iNOS?mRNA and iNOS protein expressions by 0.21,0.19,0.11 folds and 0.73,0.48,0.32 folds,indicating that yellow tea could reduce NO production through down-regulating the expression of iNOS both in transcriptional and translational level.3.Anti-cancer activity of six types of tea?1?The anti-proliferative activity of six types of tea against different cancer cell lines?HCT116,colon;Hep G2,liver;MDA-MB-231,breast?was evaluated using methyl thiazolyl tetrazolium?MTT?assay.Results showed that all six types of tea were relatively more sensitive to HCT116 cells in comparison with HepG2 and MDA-MB-231 cells.Moreover,comparing with the other five types of tea,white tea displayed the highest anti-proliferative activity against HCT116 cells.After treatment with various concentrations of white tea extract for 24 h,48 h,and 72 h,the IC ₅₀ values for HCT116cells were 409.93,339.48,and 230.18?g/mL,respectively.?2?After 48 h of treatment,white tea extract induced apoptosis in HCT116 cells in a dose-dependent manner,suggesting that anti-proliferative activity of white tea toward HCT116 cells was associated with apoptosis induction.Moreover,comparing with the control group,treatment of HCT116 cells with white tea extract significantly upregulated pro-apoptotic Bax expression and downregulated anti-apoptotic Bcl-2 expression,which could reduce the mitochondria membrane potential,and triggered the release ofcytochrome cfrom mitochondria into cytosol.Furthermore,white tea extract treatment activated caspase-9,caspase-3,and increased the cleaved form of poly?ADP-ribose?polymerase?PARP?,which participates in DN A fragmentation,leading to apoptotic death.These results suggested that mitochondria-mediated apoptotic pathway was involved in HCT116 cells apoptosisinduced by white tea extract.4.Correlation analysesCorrelation analysis showed thattotal polyphenolsand catechins had a significant positive correlation with the antioxidant activity of six types of tea,including DPPH,ABTS,FRAP,and CAA assays.Correlation analysis also showed that total polyphenols and catechins had a significant negative correlation with the IC₅₀ values of NO-scavenging and NO-suppressing,TNF-?and IL-6 production.Similarcorrelationpatterns were observed between total polyphenols and catechins and the IC₅₀ values for HCT116,HepG2,and MDA-MB-231 cells proliferation.These results suggested that tea polyphenols and catechins could be the major fucnctional components in six types of tea to exert antioxidant,anti-inflammatory,and anti-proliferative activities.5.Antioxidant,anti-inflammatory,and anti-cancer activities of EGCGAccording to the results of correlation analysis,this study further investigated the functionalproperties of EGCG,which is the majorform of tea catechins.Data showed that EGCG possessed strong antioxidant,anti-inflammatory,and anti-cancer activities,preliminarily verifying that the functional properties of six types of tea were correlated totea polyphenols and catechins.