Alpinia katsumadai HAYATA Seed Extract Inhibit LPS-Induced Inflammation by Induction of Heme Oxygenase-1 in RAW264.7 Cells

Abstract

In the present study, we investigated the effects of Alpinia katsumadai H(AYATA) (Zingiberaceae) seed ethanolic extract (AKEE) and its three components on the production of inflammatory mediators and some potential underlying mechanisms in lipopolysaccharide (LPS)-induced inflammation RAW264.7 cells. The whole formula, AKEE, and three major component compounds were then evaluated for their effects on inflammation-related parameters using LPS-induced RAW264.7 cells. Production of namely nitric oxide (NO) and cytokine levels were measured by the Griess reagent and ELISA, respectively. To investigate the underlying mechanisms of anti-inflammatory activities of AKEE, protein expression of nitric oxide synthase (inducible nitric oxide synthase, iNOS), heme oxygenase-1 (HO-1), and nuclear factor-kappa B (NF-κB) were evaluated by western blot analysis. AKEE and the major group of compounds in AKEE (alpinetin, cardamonin, and pinocembrin) complement exert anti-inflammatory effects for NO and PGE(2) production. In addition, AKEE treatment significantly inhibited the LPS-induced production of interleukin-6 and tumor necrosis factor (TNF)-α, as well as the expression of iNOS. AKEE also induced HO-1 expression in RAW264.7 cells and inhibited the nuclear translocation of NF-κB by preventing degradation of the inhibitor kappa B-alpha. We also demonstrated that the effects of AKEE on TNF-α production were partially reversed by the HO-1 inhibitor tin protoporphyrin. These results indicate that AKEE and its major component may have anti-inflammatory activity via induction of HO-1 expression was partly responsible for the anti-inflammatory effects.