Effects of Maojian tea, Tieguanyin tea and Puer tea water extracts on H₂O₂-induced oxidative stress in RAW 264.7 cells

Objective To explore the in vitro antioxidant effects of water extracts of Maojian tea, Tieguanyin tea, and Puer tea and their protective effects on hydrogen peroxide (H₂O₂) induced injury in RAW264.7 cells. Methods The contents of tea polyphenols in the three extracts were determined by Folin colorimetry. The 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) method and the ferric reducing antioxidant power (FRAP) assay were used to evaluate the in vitro antioxidant activities of three tea polyphenols extracts. The protective effects of the three tea polyphenols extracts on H₂O₂ induced injury in macrophages RAW264.7 cells were detected by MTT assay. Results The contents of tea polyphenols were (46.79±0.99)%, (46.22±1.03)% and (33.72±0.60)% in the polyphenols extracts of Maojian tea, Tieguanyin tea and Puer tea, respectively. The DPPH free radical scavenging concentrations (IC₅₀) were 4.33, 4.91 and 13.49 mg/L in the water extracts of Maojian tea, Tieguanyin tea, and Puer tea, respectively. The FRAP values were (350.89±3.11), (261.55±2.98) and (109.97±3.25) mmol/L for the water extracts of Maojian tea, Tieguanyin tea and Puer tea, respectively. The water extracts of three kinds of tea exhibited good protective effects against H₂O₂ induced oxidative stress in RAW264.7 cells when the concentrations were lower than 80 mg/L. Conclusions The DPPH free radical scavenging ability and FRAP value of tea polyphenols extract are Maojian tea>Tieguanyin tea>Puer tea. The antioxidant activity of the extract is also positively correlated with the tea polyphenol content. The water extracts of three kinds of tea have protective effects against H₂O₂ induced oxidative stress in RAW264.7 cells.