1. Academic Validation
  2. Inhibition of nitric oxide synthase expression by PPM-18, a novel anti-inflammatory agent, in vitro and in vivo

Inhibition of nitric oxide synthase expression by PPM-18, a novel anti-inflammatory agent, in vitro and in vivo

  • Biochem J. 1997 Dec 1;328 ( Pt 2)(Pt 2):363-9. doi: 10.1042/bj3280363.
S M Yu 1 J F Wu T L Lin S C Kuo
Affiliations

Affiliation

  • 1 Department of Pharmacology, Chang Gung Medical College, 259 Wen-Hwa 1st Road, Kwei-San, Tao-Yuan, Taiwan.
Abstract

We studied the effect of PPM-18, a chemically synthesized naphthoquinone derivative and also an anti-inflammatory agent, on the lipopolysaccharide (LPS)-activated inducible NO Synthase (iNOS) expression in rat alveolar macrophages. Pretreatment of macrophages with PPM-18 (0.1-10 microM) significantly inhibited nitrite production, iNOS protein expression and iNOS mRNA accumulation. PPM-18 did not directly affect the enzymic activities of iNOS and other constitutive NOS forms. The LPS-induced increase in nuclear transcription factor kappaB (NF-kappaB) p65 and p50 in nucleus was suppressed by PPM-18 (10 microM). Moreover electrophoretic mobility-shift assays demonstrated that PPM-18 inhibited DNA binding to NF-kappaB induced by LPS in whole cells but not when added in the nuclear extract, suggesting that PPM-18 did not interfere directly with the binding of NF-kappaB to DNA and that some events had to be processed before NF-kappaB could bind DNA. Examination of NF-kappaB showed that PPM-18 stabilized the NF-kappaB inhibitor, IkappaBalpha, by preventing its degradation from NF-kappaB. Therefore the stabilization of IkappaBalpha might have contributed to the inhibition of NF-kappaB activation. These results also indicate strongly that NF-kappaB is involved in the production of NO on stimulation by LPS. PPM-18 significantly decreased the production of tumour necrosis factor alpha in response to LPS. PPM-18 protects mice against LPS-induced lethal toxicity. These results also indicate that PPM-18 is a potent inhibitor of iNOS expression by blocking the binding of NF-kappaB to promoter and exerts a beneficial effect in the mouse model of sepsis.

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