Antioxidative effect of sesame coat on LDL oxidation and oxidative stress in macrophages

The effects of ethanolic extract of sesame (Sesamum indicum L.) coat (EESC) on oxidation of low-density lipoprotein (LDL) and production of nitric oxide in macrophages were investigated. The results show that EESC in the range of 0.01–0.8 mg/ml markedly inhibited copper-induced LDL oxidation and H2O2-induced cell damage. In addition, EESC at 0.1 mg/ml not only enhanced glutathione (GSH) levels, but also increased activity of GSH peroxidase, GSH reductase, GSH transferase and catalase by 3.32-, 3.39-, 1.60- and 2.26-fold compared to the control, respectively. Moreover, EESC showed dose-dependent inhibitory effects on nitric oxide production in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages and in sodium nitroprusside (SNP), a NO donor. The generation of prostaglandin E2 (PGE2) in stimulated macrophages was also reduced by EESC. The induction of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) proteins in activated macrophages was inhibited by EESC. In addition, the levels of iNOS and COX-2 mRNA in activated macrophages were decreased by EESC when determined by reverse transcription-polymerase chain reaction (RT-PCR) analysis. Furthermore, LPS-induced degradation of IκB-α was down regulated by EESC, indicating that EESC prevented LPS-induced NF-κB activation. These results implied that EESC could exhibit a protective action on biomolecules and generation of inflammatory mediators in vitro.