Inhibitory effect of Koreinsis chinensis leaves extract on proinflammatory responses in lipopolysaccharide-induced Raw 264.7 cells

Hyaluronidase inhibitory activity as inflammatory factor of Koreinsis chinensis leaf ethanol extract was showed higher inhibitory activity than water extract. 29.5% inhibitory activity was shown at concentration of 200 μg/mL phenolics. Lipopolysaccharide (LPS)-stimulated Raw 264.7 cells were treated with different concentrations (5-25 μg/mL) of Koreinsis chinensis leaf extract and the amount of nitric oxide (NO) was determined; LPS-treated cells produced 3 times more NO than non-LPS treated cells. Moreover, the NO production in cells treated with Koreinsis chinensis leaf extract showed inhibitory effect in a concentration-dependent manner. Due to the stimulantinduced NO production is regulated by the inducible nitric oxide synthase (iNOS), we determined the iNOS protein level to elucidate the mechanism by which the NO production was inhibited. It was reduced by 40% with a Koreinsis chinensis leaf extract concentration of 25 μg/mL and identified iNOS inhibition in dose-dependent manner. The prostaglandin E2 production in cells treated with Koreinsis chinensis leaf extract was reduced by 26.2% at concentration of 25 μg/mL. The protein expression of cyclooxygenase-2 in LPS-treated Raw 264.7 cells was inhibited by 64% at 25 μg/mL of Koreinsis chinensis leaf extract. Koreinsis chinensis leaf extract had a concentration-dependent inhibitory effect on the production of tumor necrosis factor-α and interleukin- 6 as pro-inflammatory cytokine in LPS-treated Raw 264.7 cells at 25 μg/mL of Koreinsis chinensis leaf extract. Their levels were decreased by 61.7 and 62% respectively.