石榴皮提取物通过抑制炎症和氧化应激改善小鼠结肠炎

Pomegranate peel extract ameliorates colitis by reducing inflammation and oxidative stress in mice

目的探讨石榴皮提取物(pomegranate peel extract,PPE)对溃疡性结肠炎(ulcerative colitis,UC)的治疗作用及机制。方法采用分光光度法测定PPE中总酚含量,高效液相色谱法分析PPE中主要成分。将24只雌性C57BL/6小鼠随机分为4组:正常组、模型组、PPE低剂量组和PPE高剂量组,每组6只。除正常组外,其他3组小鼠连续7 d给予含3%的葡聚糖硫酸钠(dextran sulfate sodium,DSS)饮用水诱导UC模型。从DSS造模给药第1天起,正常组和模型组每日以蒸馏水灌胃,PPE各组分别给予200 mg/kg和400 mg/kg的PPE灌胃,1次/d,连续10 d。通过记录体质量、疾病活动指数(DAI)、结肠长度和结肠组织病理学变化评估UC的严重程度。采用实时定量PCR(real-time quantitative,RT-qPCR)检测小鼠结肠组织中肿瘤坏死因子-α(TNF-α)、白细胞介素17A(IL-17A)、干扰素γ(IFN-γ)的mRNA相对表达水平,试剂盒法检测丙二醛(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GPX)活性。结果PPE中总酚含量为(295.76±3.15)mg/g,主要成分为没食子酸、安石榴苷及鞣花酸。与正常组比较,模型组小鼠的体质量降低、结肠缩短、DAI指数和组织病理评分增加(P<0.01),TNF-α、IL-17A、IFN-γ和MDA的表达水平增加(P<0.05),SOD和GPX活性降低(P<0.01)。与模型组比较,PPE低剂量组和高剂量组小鼠的体质量和结肠长度增加、DAI指数和组织病理评分降低(P<0.05),小鼠结肠组织中TNF-α、IL-17A、IFN-γ和MDA的表达水平降低(P<0.05),GPX活性增加(P<0.05),SOD差异无统计学意义(P>0.05)。结论PPE可以通过抗炎和抗氧化活性改善DSS诱导的小鼠溃疡性结肠炎。

Objective To explore the therapeutic effect of pomegranate peel extract(PPE)on ulcerative colitis(UC).Methods The content of total phenol in PPE was determined by spectrophotometry and its main components were characterized by HPLC.Twenty-four female C57BL/6 mice were randomly divided into four groups:normal group,model group,PPE low-dose group,and PPE high-dose group,with six mice in each group.The mice were administered with 3%dextran sulfate sodium(DSS)for 7 d in drinking water to induce UC.From the first day of DSS administration,the mice were gavaged with distilled water every day for 10 d in normal group and model group,whereas the mice were orally administered with 200 mg/kg and 400 mg/kg PPE in PPE groups once a day for 10 d,respectively.Body weight,disease activity index(DAI),colon length,and colon histopathology were observed and detected to evaluate the severity of colitis.The mRNA expression levels of TNF-α,IL-17A,and IFN-γ were detected by RT-qPCR.The levels of malon-dialdehyde(MDA),superoxide dismutase(SOD),and glutathione peroxidase(GPX)were also measured by kit method.Results The total phenol content was(295.76±3.15)mg/g in PPE.Major identified constituents of PPE were gallic acid,granatine,and ellagic acid.Compared to normal group,the body weight was decreased,the colon length was shortened,the disease activity index(DAI)was elevated,and the histological damage score was increased in model group(all P<0.01).Compared with normal group,the expressions of TNF-α,IL-17A,IFN-γ and MDA in colon of model group were up regulated(P<0.05),while the activities of SOD and GPX were suppressed(P<0.01).Compared with model group,the body weight and the colon length were increased,while DAI and the histological damage score were reduced in low-and high-dose PPE groups(P<0.05).Compared with model group,the expressions of TNF-α,IL-17A,IFN-γ,and MDA were decreased in PPE groups,while the activity of GPX was increased(P<0.05),and there was no significant difference in SOD(P>0.05).Conclusion PPE can attenuate the DSS-induced UC symptoms by anti-inflammatory and antioxidant activities.