Pentamethyl-hydroxychromane, vitamin E derivative, inhibits induction of nitric oxide synthase by bacterial lipopolysaccharide.

Vitamin E, a lipophilic antioxidant, has effectively inhibited the activation of cytokine-induced nuclear factor kB (NFkB). Since NFkB plays a critical role in the induction of an isoform of nitric oxide synthase (iNOS) gene by lipopolysaccharide (LPS), we investigated the effect of a vitamin E derivative, pentamethyl-hydroxychromane (PMC), which is an extremely potent inhibitor of NFkB activation, on the induction of nitric oxide (NO) synthesis and iNOS mRNA by LPS. PMC inhibited the LPS-stimulated induction of NO production in a concentration-dependent fashion in cultured J774 macrophages and rat vascular smooth muscle cells without evidence of cytotoxicity. However, the addition of PMC to J774 macrophages after the induction of iNOS did not inhibit NO production. Treatment of J774 macrophages with LPS resulted in a significant expression of iNOS mRNA, which was profoundly reduced by PMC. Data suggest that PMC inhibits the induction of iNOS by preventing iNOS gene expression through inhibition of NFkB activation.