Anti-inflammatory activities of six types of tea in LPS-induced RAW264.7 cells

According to the classical processing technology, tea can be categorised into six types: green tea, white tea, yellow tea, oolong tea, puer tea, black tea. This study aimed to investigate anti-inflammatory property of six types of tea, including Yunnan Daye ( green tea, black tea, and puer tea) , Fuding Dabai ( white tea) , Junshan Yinzhen ( yellow tea) , and Jin Guanyin ( oolong tea) . Nitric oxide ( NO) -scavenging assay and LPS-induced RAW264.7 cells model were used to assess the anti-inflammatory activity of water extract of six types of tea.The results showed that, among six types of tea, green, white, and yellow tea displayed stronger NO-scavenging capacity with IC50 values ranging from 99.27 to 104.83 μg/m L. Compared with other five types of tea, yellow tea exhibited significant anti-inflammatory activity against LPS-induced RAW264.7 cells. The IC50 values of yellow tea for NO-suppressing effect was 398.13 μg/m L, and the inhibition rate for tumor necrosis factor-α ( TNF-α) and interleukin-6 ( IL-6) reached 69.25% and 87.68%, respectively, at a concentration of 500 μg/m L. Compared with LPS-induced group, treatment with water extract of yellow tea significantly down-regulated the expression of i NOS mRNA and decreased i NOS protein level. Correlation analysis showed that the content of tea polyphenols had a significant negative correlation with the IC50 values of NO-scavenging and NO-suppressing, TNF-α and IL-6 productions. In conclusion, all six types of tea possessed anti-inflammatory property. Among six types of tea, yellow tea exerted the strongest inhibitory effect on production of pro-inflammatory mediators ( NO, TNF-α, and IL-6) , and could reduce NO production through down-regulating the expression of i NOS both in transcriptional and translational level.