Orazipone [
OR-1384; 3-[4-(methylsulfonyl)benzylidene]
pentane-2,4-dione] is a novel sulfhydryl-modulating compound that has anti-inflammatory properties in experimental models of
asthma and
inflammatory bowel disease. In
inflammation, inducible nitricoxide synthase (iNOS) generates NO, which modulates the immune response. Compounds that inhibit iNOS expression or iNOS activity possess anti-inflammatory effects. In the present study, we examined the effects of
orazipone and its derivative
OR-1958 [3-[3-
chlorine-4-(methylsulfonyl)benzylidene]
pentane-2,4-dione] on iNOS expression and NO production in J774 macrophages stimulated by bacterial
lipopolysaccharide (LPS) and in human alveolar epithelial cells activated by proinflammatory
cytokines.
Protein expression and nuclear translocation of
transcription factors were measured by Western blot. iNOS
mRNA expression was determined by quantitative reverse transcription-polymerase chain reaction and iNOS mRNA stability by
actinomycin D assay. iNOS promoter activity was studied in a cell line expressing
luciferase under the control of iNOS promoter.
Orazipone and its derivative
OR-1958 but not its nonthiol-modulating analog inhibited iNOS expression and NO production in a concentration-dependent manner.
Orazipone decreased LPS-induced iNOS
mRNA expression, but the decay of iNOS
mRNA was not affected.
Orazipone extensively prevented LPS-induced activation of
nuclear factor kappaB (
NF-kappaB) and signal transducer and activator of transcription (STAT) 1, which are important
transcription factors for iNOS. In agreement, human iNOS promoter activity was inhibited by
orazipone. In conclusion,
orazipone decreased activation of inflammatory
transcription factors NF-kappaB and STAT1, and expression of iNOS in cells exposed to inflammatory stimuli. The thiolmodulating property seems to be critical in mediating the antiinflammatory effects of
orazipone.