Ursolic Acid Isolated from the Seed of Cornus officinalis Ameliorates Colitis in Mice by Inhibiting the Binding of Lipopolysaccharide to Toll-like Receptor 4 on Macrophages

• Published in: Journal of agricultural and food chemistry 2014-10, Vol.62 (40), p.9711-9721
• Main Authors: Jang, Se-Eun, Jeong, Jin-Ju, Hyam, Supriya R, Han, Myung Joo, Kim, Dong-Hyun
• Format: Article
• Language: English
• Subjects: Animals; Anti-Inflammatory Agents, Non-Steroidal - pharmacology; colitis; Colitis - chemically induced; Colitis - drug therapy; Colitis - metabolism; colon; Cornus - chemistry; Cornus officinalis; Cytokines - metabolism; ethanol; fluorescence; fluorescent dyes; IKappaB kinase; inducible nitric oxide synthase; Inflammation Mediators - metabolism; interleukin-10; interleukin-1beta; interleukin-6; lipopolysaccharides; Lipopolysaccharides - metabolism; Lipopolysaccharides - pharmacology; macrophages; Macrophages, Peritoneal - drug effects; Macrophages, Peritoneal - metabolism; Male; mice; Mice, Inbred C57BL; mitogen-activated protein kinase; myeloperoxidase; NF-kappa B - metabolism; nitric oxide; oral administration; Peptidoglycan - pharmacology; phosphorylation; prostaglandin synthase; Seeds - chemistry; signal transduction; small interfering RNA; tissues; Toll-like receptor 4; Toll-Like Receptor 4 - genetics; Toll-Like Receptor 4 - metabolism; transcription factor NF-kappa B; Trinitrobenzenesulfonic Acid - toxicity; Triterpenes - pharmacology; tumor necrosis factor-alpha; Ursolic Acid
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf501487v

Ursolic acid, which was isolated from an ethanol extract of Cornus officinalis seed, potently inhibited nuclear factor κ light-chain enhancer of activated B cells (NF-κB) activation in lipopolysaccharide (LPS)-stimulated peritoneal macrophages. Therefore, we investigated the anti-inflammatory mechanism of ursolic acid in LPS-stimulated macrophages and colitic mice. Ursolic acid inhibited phosphorylation of interleukin 1 receptor-associated kinase (IRAK)1, TAK1, inhibitor of nuclear factor κB kinase subunit β (IKKβ), and IκBα as well as activation of NF-κB and MAPKs in LPS-stimulated macrophages. Ursolic acid suppressed LPS-stimulated interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, cyclooxygenase (COX)-2, and inducible NO synthetase (iNOS) expression as well as PGE2 and NO levels. Ursolic acid not only inhibited the Alexa Fluor 488-conjugated LPS-mediated shift of macrophages but also reduced the intensity of fluorescent LPS bound to the macrophages transiently transfected with or without MyD88 siRNA. However, ursolic acid did not suppress NF-κB activation in peptidoglycan-stimulated macrophages. Oral administration of ursolic acid significantly inhibited 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colon shortening and myeloperoxidase (MPO) activity in mice. Ursolic acid also suppressed TNBS-induced COX-2 and iNOS expression as well as NF-κB activation in colon tissues. Ursolic acid (20 mg/kg) also inhibited TNBS-induced IL-1β, IL-6, TNF-α by 93, 86, and 85%, respectively (p < 0.05). However, ursolic acid reversed TNBS-mediated downregulation of IL-10 expression to 79% of the normal control group (p < 0.05). On the basis of these findings, ursolic acid may ameliorate colitis by regulating NF-κB and MAPK signaling pathways via the inhibition of LPS binding to TLR4 on immune cells.