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

Abstract

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.

Anti-inflammatory effects of ginsenoside Rg1 and its metabolites ginsenoside Rh1 and 20(S)-protopanaxatriol in mice with TNBS-induced colitis

“…Their peritoneal cavities were swilled with 10 ml of RPMI 1640 and the peritoneal lavage fluids were collected and centrifuged (300g, 10 min) (Jang et al, 2014). Collected cells were resuspended with RPMI 1640 and plated.…”

“…For the ELISA assay, cell supernatents prepared from macrophages were transferred to 96-well ELISA plates. Cytokines levels were determined using ELISA kits (Jang et al, 2014). For the immunoblot analysis, cell supernatants were applied to 10% SDS-PAGE and transferred onto polyvinylidene difluoride membranes (Jang et al, 2014).…”

“…Cytokines levels were determined using ELISA kits (Jang et al, 2014). For the immunoblot analysis, cell supernatants were applied to 10% SDS-PAGE and transferred onto polyvinylidene difluoride membranes (Jang et al, 2014). The membranes were blocked with 5% non-fat dried-milk proteins in 0.05% phosphate-buffered saline with tween 20 (PBST), then probed with COX-2, iNOS, IRAK1, p-IRAK1, TAK1, p-TAK1, p-IκBα, IκBα, p65, p-p6, or β-actin antibody.…”

Ursolic acid protects against ulcerative colitis via anti-inflammatory and antioxidant effects in mice

“…UA is well known to possess various biological activities, including anti-inflammatory (5,6), anticancer (7,8), hypoglycemic (9), antioxidant (10)(11)(12) and immunomodulatory activities (13). Previously, UA was reported to be involved in colitis in a number of publications (4,14,15). Hawthorn berry extract containing 0.5% UA decreased edema and the infiltration of neutrophils in the colonic tissues of acetic acid-treated rats (14).…”

“…UA significantly inhibits the production of pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6, and the expression of cyclooxygenase-2 and inducible nitric oxide (NO) synthetase in lipopolysacharride (LPS)-stimulated macrophages and colonic tissues from 2,4,6-trinitrobenzenesulfonic-treated mice (4,15). UA also exerts an inhibitory effect on the activation of nuclear factor (NF)-κB in human intestinal epithelial cells and macrophages (4,15). These results indicate a protective role of UA in colitis.…”