molecules Article
Glycyrrhetic Acid Ameliorates Dextran Sulfate Sodium-Induced Ulcerative Colitis in Vivo Yong-Deok Jeon 1 , Sa-Haeng Kang 1 , Keuk-Soo Bang 1 , Young-Nam Chang 1 , Jong-Hyun Lee 2 and Jong-Sik Jin 1, * 1
2
*
Department of Oriental Medicine Resources, Chonbuk National University, 79 Gobongro, Iksan 570-752(1), Korea;
[email protected] (Y.-D.J.);
[email protected] (S.-H.K.);
[email protected] (K.-S.B.);
[email protected] (Y.-N.C.) Department of Pharmacy, College of Pharmacy, Dongduk Woman’s University, 23-1 Wolgok-Dong, SungBuk-Gu, Seoul 136-714, Korea;
[email protected] Correspondence:
[email protected]; Tel.: +82-63-850-0744
Academic Editor: Derek J. McPhee Received: 25 January 2016; Accepted: 14 April 2016; Published: 22 April 2016
Abstract: Glycyrrhizae Radix (GR) is a Korean traditional herb medicine that is widely used in clinical health care. Glycyrrhetic acid (GA) is an aglycone saponin extracted from GR that has anti-inflammatory, anti-cancer, and anti-viral effects. However, the anti-inflammatory effects of GA in colitis have not been reported. This study investigated the role of GA on ulcerative colitis in a dextran sulfate sodium (DSS)-induced mouse colitis model. DSS-treated mice displayed weight loss and shortened colon length compared with control mice. Mice administered GA showed less weight loss and longer colon length than the DSS-treated group. Interleukin (IL)-6, IL-1β, and tumor necrosis factor-alpha were decreased by GA treatment. GA treatment also reduced DSS-induced microscopic damage to colon tissue. GA regulates the phosphorylation of transcription factors including nuclear factor-kappa B (NF-κB) and IκB alpha, and regulates the expression of cycloxygenase-2 and prostaglandin E2 . GA thus showed beneficial effects in a mouse model of colitis, implicating GA might be a useful herb-derived medicine in the treatment of ulcerative colitis. Keywords: glycyrrhetic acid; ulcerative colitis; dextran sulfate sodium; anti-inflammation
1. Introduction Ulcerative colitis (UC) is a chronic and relapsing inflammatory disease characterized by dysregulation of the immune function response and imbalanced release of cytokines and unresolved inflammatory progress associated with intestinal mucosa [1,2]. The inflammation reaction may be initiated by pro-inflammatory cytokines [3]. Patients with bowel disease have increased interleukin (IL)-6 in the intestinal mucosa and tumor necrosis factor-alpha (TNF-α) in the blood and colon tissue. Immune cells, such as T cells, intestinal epithelial cells, and macrophages, secrete various cytokines including TNF-α, IL-1 family, IL-6, IL-8, and interferon-gamma (IFN-γ), which regulate the inflammatory response in UC. Elevated levels of cytokines have also been implicated in the pathogenesis of bowel disease [4,5]. Dextran sulfate sodium (DSS)-induced colitis is considered as a suitable model that represents the disease both morphologically and biochemically. Intake of DSS induces bloody stools, ulcerations, epithelial injury, and infiltration of inflammatory cells [6]. Histologically, DSS causes crypt abscesses and epithelioglandular hyperplasia in mice. These colon conditions are similar to acute and chronic UC in humans. DSS is toxic to gut epithelial cells of the basal crypts and affects the integrity of the mucosal barrier [7]. Thus, the DSS-induced colitis model is especially suitable to study the mechanism of inflammatory colitis.
Molecules 2016, 21, 523; doi:10.3390/molecules21040523
www.mdpi.com/journal/molecules
Molecules 2016, 21, 523 Molecules 2016, 21, 523
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Cyclooxygenase-1 Cyclooxygenase-1(COX-1) (COX-1)isisaaconstitutive constitutiveenzyme enzymethat thatcatalyzes catalyzesthe theproduction productionofofprostaglandins prostaglandins (PGs), which protect the stomach from damage. COX-2 is induced by inflammatory stimuli, suchsuch as (PGs), which protect the stomach from damage. COX-2 is induced by inflammatory stimuli, cytokines, andand alsoalso catalyzes PGPG production that contributes toto inflammation-related as cytokines, catalyzes production that contributes inflammation-relatedswelling swelling[8]. [8]. COX-2 and PGE2 levels are raised in the inflamed mucosa of patients with UC [9]. COX-2 and PGE2 levels are raised in the inflamed mucosa of patients with UC [9]. Glycyrrhiza Glycyrrhizauralensis uralensis(GU) (GU)isisaamedicinal medicinalplant plantused usedininEurope Europeand andAsia Asiafor fortreating treatingdebilitating debilitating UC. It has been also used for diseases of the respiratory system and gastrointestinal UC. It has been also used for diseases of the respiratory system and gastrointestinaltract tract[10]. [10]. Glycyrrhizae Radix (GR) has been traditionally used for treatment of cough, allergy, and Glycyrrhizae Radix (GR) has been traditionally used for treatment of cough, allergy, andbowel bowel disease disease[11]. [11]. GR GRpossesses possessesvarious variousbioactive bioactiveconstituents constituentsthat thatinclude includesaponins, saponins,flavonoids, flavonoids,and and coumarins [12]. However, it is unknown whether the constituents of GR can regulate coumarins [12]. However, it is unknown whether the constituents of GR can regulateintestinal intestinal inflammation. inflammation.Glycyrrhetic Glycyrrheticacid acid(GA) (GA)is isa atriterpenoid triterpenoidsaponin saponinfound foundininGU GUasasaa hydrolyzed hydrolyzed metabolite of glycyrrhizin [13]. Recent studies have demonstrated that GA has strong antioxidant, metabolite of glycyrrhizin [13]. Recent studies have demonstrated that GA has strong antioxidant, anti-inflammation, anti-inflammation,and andanti-cancer anti-cancereffects effects[14]. [14].GA GAcan canreduce reducethe theoxidative oxidativestress stresscaused causedby bycarbon carbon tetrachloride, reduces production of pro-inflammatory cytokines, and repress immune function tetrachloride, reduces production of pro-inflammatory cytokines, and repress immune function[15]. [15]. These results suggest that GA has inhibitory effects on DSS-induced colitis model. These results suggest that GA has inhibitory effects on DSS-induced colitis model. To To explore explore the the potential potential of of GA GA as as aa useful useful therapeutic therapeutic inin UC, UC, we we examined examinedits its effects effects on on DSS-induced UC in a mouse model. The aims were to evaluate the effect of GA on clinical signs DSS-induced UC in a mouse model. The aims were to evaluate the effect of GA on clinical signs including includingweight weightloss, loss,colon colonshortening, shortening,diarrhea, diarrhea,and andgross grossbleeding, bleeding,and andtotoinvestigate investigatethe therole roleofof GA on inflammatory mediators in DSS-treated mice. GA on inflammatory mediators in DSS-treated mice. 2.2.Results Results 2.1.Effects EffectsofofGA GAon onClinical ClinicalSigns SignsininDSS-Induced DSS-InducedColitis Colitis 2.1. Whenmice micewere weretreated treatedwith withDSS DSStotoinduce inducecolitis, colitis,body bodyweight weightwas wasreduced reducedand andcolon colonlength length When wasshortened shortenedatatday day10 10by by19.02 19.02±˘1.51 1.51ggand and28.6% 28.6%respectively, respectively,compared comparedtotothe thecontrol controlgroup group was (Figures1A 1Aand and 2A,B). Both 10 and 50 mg/kg alleviated the effects body loss weight (Figures 2A,B). Both GAGA 10 and GAGA 50 mg/kg alleviated the effects of DSS of onDSS bodyon weight by loss by 20.86 ˘ 1.76 g± and ˘ 1.25 and colon by shortening 13.2%respectively and 12.7%, (Figure respectively 20.86 ± 1.76 g and 22.05 1.2522.05 g, and colong,shortening 13.2% andby12.7%, 1B). (Figure activity 1B). Disease activity wereat increased by 4.0 1.00 in DSS-treated Disease index (DAI)index scores(DAI) werescores increased day 10 at byday 4.0 10 ± 1.00 in ˘DSS-treated group, group, compared to the control GA attenuated also attenuated the DSS-mediated increase DAIscores scoresatat compared to the control group.group. GA also the DSS-mediated increase in in DAI day10 10by by2.8 2.8±˘0.45, 0.45,2.2 2.2± ˘ 0.84; GA GA mg/kg. day 0.84; GA 10,10, GA 5050 mg/kg.
(A)
(B)
Figure GA onon clinical signs in DSS-induced colitis. (A) (A) Body weight was was measured at theat Figure1.1.Effects Effectsofof GA clinical signs in DSS-induced colitis. Body weight measured same time on theon experimental days; (B) Disease activityactivity index score inscore the five groups. the same time the experimental days; (B) Disease index in study the five study Values groups. # p < 0.05 vs. control # represent mean ± S.E.M. (n = 6). Data were analyzed by Student’s t-test ( andvs. * pcontrol < 0.05 Values represent mean ˘ S.E.M. (n = 6). Data were analyzed by Student’s t-test ( p < 0.05 vs. DSS alone). and * p < 0.05 vs. DSS alone).
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(A) (A)
(B) (B)
Figure2.2.Effects Effectsofof GA DSS-induced colon shortening. (A) Average colon length in cm measured Figure GA onon DSS-induced colon shortening. (A) Average colon length in cm measured after Figure Effects of GA shortening. (A) Average colon length cm measured after 102.days at the timeonofDSS-induced sacrifice; (B) colon Representative colons of each group. Valuesinrepresent mean 10 days at the time of sacrifice; (B) Representative colons of each group. Values represent mean ˘ S.E.M. after 10 days at Data the time sacrifice;by(B) Representative ofcontrol each group. represent mean ± S.E.M. (n = 6). wereofanalyzed Student’s t-test (#p
