Abstract: The purpose of this study was to explore and compare the anti-inflammatory effects and the possible mechanisms of catechin and epicatechin in mouse alveolar macrophages（MH-S）. Lipopolysaccharide（LPS）was used to stimulate MH-S cells to establish a cellular inflammation model. The effects of catechin and epicatechin on MH-S cell viability were detected by MTS and LDH assays. The contents of interleukin-1β（IL-1β）, IL-6, and TNF-α in the supernatant were detected by enzyme-linked immunosorbent assay（ELISA）. Real-time quantitative polymerase chain reaction（qRT-PCR） was used to detect the mRNA transcription levels ofNos2,Il-6, Tnf-α,Grp78, Ire1α, Perk, andAtf6. The protein expression of iNOS was detected by Western Blot. The results showed that 6.25－100 μg/mL of catechin and epicatechin had no significant toxicity on MH-S cells. Both catechin and epicatechin down-regulated the secretion of IL-1β and the protein expression of iNOS in LPS-induced MH-S cells in a concentration-dependent manner. Meanwhile, catechin and epicatechin reduced the mRNA transcription levels of iNOS, IL-6 and endoplasmic reticulum stress（ERS）-related protein IRE1α. The anti-inflammatory activity of catechin was stronger than that of epicatechin at low concentrations, but catechin was lower than epicatechin at high concentrations. These results indicated that catechin and epicatechin had anti-inflammatory effects by reducing the secretion of IL-1β, IL-6 and the expression of iNOS, which might be related to the inhibition of ERS.

Key words: catechin, epicatechin, MH-S cells, inflammation, endoplasmic reticulum stress