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

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.

• Authors: S M Yu, J F Wu, T L Lin, S C Kuo
• Journal: The Biochemical journal (Biochem J) Vol. 328 ( Pt 2) Pg. 363-9 (Dec 01 1997) ISSN: 0264-6021 [Print] England
• PMID: 9371689 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Inflammatory Agents, Non-Steroidal
• DNA-Binding Proteins
• I-kappa B Proteins
• Lipopolysaccharides
• NF-kappa B
• Naphthoquinones
• Nfkbia protein, mouse
• Nfkbia protein, rat
• Nitrites
• Tumor Necrosis Factor-alpha
• alpha-benzoylamino-1,4-naphthoquinone
• NF-KappaB Inhibitor alpha
• Nitric Oxide
• Nitric Oxide Synthase

Topics

• Animals
• Anti-Inflammatory Agents, Non-Steroidal (pharmacology)
• DNA-Binding Proteins (metabolism)
• Dose-Response Relationship, Drug
• Enzyme Induction (drug effects)
• Hypotension (prevention & control)
• I-kappa B Proteins
• Lipopolysaccharides (toxicity)
• Macrophages, Alveolar (enzymology)
• Mice
• Mice, Inbred BALB C
• NF-KappaB Inhibitor alpha
• NF-kappa B (metabolism)
• Naphthoquinones (pharmacology)
• Nitric Oxide (metabolism)
• Nitric Oxide Synthase (biosynthesis, genetics)
• Nitrites (metabolism)
• Promoter Regions, Genetic
• Protein Binding
• Rats
• Rats, Wistar
• Shock, Septic (prevention & control)
• Tumor Necrosis Factor-alpha (metabolism)