Effects of Welsh onion on oxidation of low-density lipoprotein and nitric oxide production in macrophage cell line RAW 264.7

The effects of aqueous extracts of Welsh onion green leaves (WOE) on oxidation of low-density lipoproteins (LDL) and production of nitric oxide (NO) in macrophage were investigated. The results showed that WOE in the range of 0.1-1.0 mg/ml inhibited LDL oxidation and scavenged ABTS(.+) radical in an acellular system. Moreover, the antioxidant activity of WOE correlated well with the total polyphenolic content (r = 0.968). In addition, WOE in the range of 0.1-1.0 mg/mI inhibited lipopolysaccharide (LPS)-induced NO production in a concentration-dependent manner. The induction of iNOS and COX-2 proteins in RAW 264.7 cells was markedly suppressed by WOE. WOE at 1 mg/ml significantly inhibited iNOS mRNA expression, as determined by reverse transcription-polymerase chain reaction (RT-PCR). Furthermore, LPS-induced nuclear factor-kappa B (NF-kappaB) activation, through IkappaB-alpha degradation, was reduced by WOE. These results suggest that WOE could attenuate excessive NO and prostaglandin generation in macrophages and lipoprotein oxidation in vitro. (C) 2004 Elsevier Ltd. All rights reserved.