肌肽及其生理活性研究进展

肌肽(carnosine)是一种水溶性的内源二肽,具有很强的抗氧化作用。肌肽不仅可作为食品抗氧化添加剂,还是一种具有重要生物活性的化合物。本文综述了近年来国内外对肌肽的抗氧化效率、肌肽在生物体内不同部位生理活性的研究进展。     

虫茶多酚对乙酰氨基酚致小鼠肝损伤的预防效果

研究虫茶粗多酚（crude polyphenols of Insect tea,CPIT）对乙酰氨基酚致小鼠急性肝损伤的预防效果。在诱导肝损伤后,CPIT可以增加小鼠的体质量和减小肝脏质量,降低肝指数。经过CPIT处理后的小鼠较对照组小鼠（肝损伤）血清谷丙转氨酶、谷草转氨酶、乳酸脱氢酶、甘油三酯、血尿素氮含量均下降,而总胆固醇,白蛋白水平则上升。同时经过CPIT处理后,白细胞介素（interleukin,IL）-6、IL-12、肿瘤坏死因子-α和干扰素-γ的水平也较对照组小鼠降低。CPIT还可以上调肿瘤坏死因子-α、锰超氧化物歧化酶、铜锌超氧化物歧化酶、过氧化氢酶、谷胱甘肽过氧化物酶mRNA的表达和下调核转录因子（nuclear factor-κB, NF-κB）、一氧化氮合酶异型、环氧化酶的表达。通过结果可以看出,CPIT具有预防动物体内肝损伤效果。     

富硒玉米肽对扑热息痛致小鼠肝损伤的防护作用

目的：研究富硒玉米肽（selenium-enriched corn peptides,SeCPs）对扑热息痛（acetaminophen,APAP） 代谢相关酶的影响及其对肝损伤的防护作用。方法：利用碱醇液提取玉米蛋白,经酶解和超滤制备分子质量 小于5 kDa的混合玉米肽。建立扑热息痛致小鼠肝损伤模型,测定小鼠肝脏指数、血清谷草转氨酶（aspartate aminotransferase,AST）活力、肝脏中细胞色素P4502E1（cytochrome P4502E1,CYP2E1）、细胞色素P4501A2 （cytochrome P4501A2,CYP1A2）、谷胱甘肽巯基转移酶（glutathione S-transferase,GST）、尿苷二磷酸葡萄糖 醛酸转移酶（uridine diphosphate-dependent glycosyltransferase,UGT）质量浓度、磺基转移酶（sulfotransferase, SULT）、谷胱甘肽过氧化物酶（glutathione peroxidase,GSH-Px）活力及还原型谷胱甘肽（glutathione,GSH）含 量,苏木精-伊红（hematoxylin-eosin,HE）染色观察肝脏病理学变化。结果：与模型组相比,SeCPs组小鼠其肝脏 中的CYP2E1、CYP1A2、UGT质量浓度及SULT活力显著降低（P＜0.05）,GSH含量、GST质量浓度及GSH-Px活 力显著提高（P＜0.05）,肝脏指数和血清中AST活力明显降低,肝脏病理学情况显著改善。结论：SeCPs对过量扑 热息痛致肝损伤的防护作用效果显著性优于亚硒酸钠＋玉米肽,即有机硒与玉米肽有良好的协同保肝作用。     

菊苣醇提物对对乙酰氨基酚诱导小鼠肝损伤的保护作用

目的研究菊苣醇提物对对乙酰氨基酚(acetaminophen,APAP)诱导的小鼠肝损伤的保护作用。方法将56只昆明小鼠随机分为7组:分别是阴性对照组,APAP模型组,水飞蓟宾阳性对照组,菊苣醇提物单独给药组(200 mg/kg体重),菊苣醇提物低、中和高剂量(50、100和200 mg/kg体重)与APAP联用组。各剂量组小鼠灌胃给予对应药物连续7 d后,一次性腹腔注射APAP(300 mg/kg体重)构建肝损伤模型,24 h后采集肝组织样品和血清。分别测定肝组织和血清的多种氧化指标以及细胞色素P450 2E1酶(CYP2E1)的蛋白表达水平。结果菊苣醇提物能够显著降低血清中谷丙转氨酶(alanine aminotransferase,ALT)和谷草转氨酶(aspartate aminotransferase,AST)水平。降低肝组织中过氧化氢(hydrogen peroxide,H2O2)和谷胱甘肽(glutathione,GSH)的含量以及提高抗氧化酶系中过氧化氢酶(catalase,CAT)和总超氧化物歧化酶(total superoxide dismutase,T-SOD)活性;同时,体外抗氧化实验亦表明其具有良好的清除自由基的能力。另外,菊苣醇提物还能够显著抑制CYP2E1的蛋白表达。结论菊苣醇提物有助于维持小鼠体内酶防御系统功能,提高机体清除自由基的能力,并通过减少CYP2E1的蛋白表达对APAP所致小鼠肝损伤具有明显保护作用。     

太明清对扑热息痛致小鼠肝损伤的保护作用

本研究对韩国传统饮品太明清(TMC)对扑热息痛所致小鼠肝损伤的保护作用进行了研究,ICR小鼠连续14 d灌胃给予低(100 mg/kg)、中(250 mg/kg)、高(500 mg/kg)三个剂量的太明清及阳性药物水飞蓟素(100 mg/kg)后,腹腔注射扑热息痛(800mg/kg)建立动物急性肝损伤模型,动物处死后取血液和脏器测定各项指标。相对于模型对照组,太明清实验组的肝指数明显降低。三个剂量的太明清均明显降低血清谷丙转氨酶(ALT),谷草转氨酶(AST),碱性磷酸酶(ALP),甘油三酯(TG),尿素氮(BUN)水平,提高血清总胆固醇(TC),白蛋白(ALB)水平(p0.05)。且三个剂量呈现了一定的量效关系。其中太明清高剂量组对小鼠肝损伤的保护效果最佳,仅次于阳性药物水飞蓟素组(p0.05)。另外,从小鼠肝脏病理图来看,相对于模型对照组,太明清实验组对炎症及肝细胞坏死有明显改善。可见太明清对扑热息痛所致小鼠肝损伤具有较好的保护作用。     

肌肽对肉鸡生长性能及胸肌肉品质的影响

在1～4组肉鸡饮水中肌肽的添加量分别为0、20、40和60 mg/L,每周测定各组肉仔鸡的周增重、料重比,并在试验结束时胸肌采样,测定胸肌肉品质指标,观察肌肽对肉鸡生长性能和胸肌肉品质的影响.结果表明:试验的前两周,肌肽大剂量组的周增重显著高于对照组(P＜0.05);4～6周龄,各剂量组的周增重均高于对照组,但差异不显著(P＞0.05);添加肌肽能明显改善饲料转化率,提高了胸肌水分含量及pH值;降低了失水率、肌纤维的直径;胸肌粗蛋白及粗脂肪的含量略微下降;中、大剂量组的胸肌色较淡而亮度增加.     

Antioxidant Effects of Carnosine and Phytic Acid in a Model Beef System

Antioxidant and color stability effects of carnosine and phytate were compared in a fresh beef model system and in cooked beef. Both compounds increased the rate of pH decline in pre-rigor muscle. Phytate also increased the rate of post-mortem glycogen catabolism. Both antioxidants inhibited metmyoglobin formation in raw samples during storage. Phytate was more effective than carnosine for inhibition of lipid peroxidation. Heme iron content was negatively related to lipid peroxidation in cooked beef (r=–0.92). Phytate was also more effective for inhibition of iron release from heme during cooking. Phytate is recommended over carnosine as an effective antioxidant in cooked meats.     

肌肽对猪肉的氧化抑制和保鲜作用

肌肽是一种具有抗氧化等功能的天然的二肽,本试验比较了肌肽对猪肉匀浆的抗氧化作用,同时比较了不同保鲜剂对冷鲜肉保藏期的延长作用。实验发现,1mmol/L肌肽标准液对猪肉匀浆中丙二醛的形成量就能起到显著的抑制作用(P<0.05),此时对体系中脂类氧化的抑制率即达到12%,5mmol/L肌肽对体系中脂类氧化的抑制率达15%,20mmol/L肌肽对体系中脂类氧化的抑制率达47%,表明不同浓度的肌肽均能对猪肉匀浆中脂类氧化起显著的抑制作用,其中随浓度的增加效果增强。与BHT和α-生育酚相比,肌肽对TBARS的抑制能力较高。肌肽可以延长冷鲜肉的保存时间,添加了肌肽的冷鲜肉保藏时间由不添加保鲜剂的9天增加到15天,其效果要优于抗坏血酸,肌肽牛肉预煮液也可以延长冷鲜肉的贮藏时间。     

岩藻糖对小鼠免疫性肝损伤的保护作用

研究岩藻糖对卡介苗(Bacillus calmette-guerin,BCG)和脂多糖(lipopolysaccharide,LPS)诱导的免疫性肝损伤小鼠的保护作用。将30只小鼠分为5组,每组6只,第1天除正常组外,其余小鼠尾静脉注射BCG;第2天岩藻糖低、高剂量组分别灌胃20、100 mg/(kg·d)岩藻糖,阳性对照组灌胃0.1 mg/(kg·d)地塞米松,正常组和模型组小鼠灌胃等量蒸馏水,连续给药14 d,末次灌胃2 h后,除正常组外其余小鼠尾注射LPS;计算小鼠脏器指数,用试剂盒测定血清中谷丙转氨酶(alanine aminotransferase,ALT)、谷草转氨酶(aspartate aminotransferase,AST)、超氧化物歧化酶(superoxide dismutase,SOD)及过氧化氢酶(catalase,CAT)活力,检测丙二醛(malondialdehyde,MDA)、NO、肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)、白细胞介素-1β(interleukin-1β,IL-1β)含量;肝组织苏木精-伊红染色并观察;Western blot法测定肝组织核浆分离后核因子-κB(nuclear factor-κB,NF-κB)、核因子-κB抑制剂α(inhibitor of nuclear factor-κBα,IκBα)含量。结果显示,与模型组相比,高剂量岩藻糖能显著减少脏器指数(P0.05),显著降低ALT、AST活力和MDA、NO、TNF-α、IL-1β、NF-κB含量(P0.05),显著提高SOD、CAT活力及IκBα含量(P0.05);病理切片显示肝脏病变得到逆转,与正常组接近。实验结果表明岩藻糖对免疫性肝损伤小鼠有明显的保护作用,可能通过NF-κB/IκBα信号通路来实现。     

榆干离褶伞溶栓酶对酒精诱导大鼠肝损伤的保护作用

目的：研究榆干离褶伞溶栓酶（Lyophyllum ulmarium fibrinolytic enzyme,LUFE）对酒精诱导大鼠肝损伤的保护作用。方法：将大鼠随机分为4 组,即正常对照组,模型组,LUFE低、高剂量组。除正常对照组以外,其余各组每日按10 mL/kg mb灌胃体积分数40%的酒精诱导肝损伤。LUFE低、高剂量组分别以100、400 mg/kg mb的剂量灌胃LUFE,正常对照组和模型组以等量生理盐水灌胃,共28 d。末次给药后次日处死大鼠,苏木精-伊红染色观察大鼠肝组织病理形态学变化,检测血清丙氨酸氨基转移酶（alanine transaminase,ALT）、天冬氨酸氨基转移酶（aspartate aminotransferase,AST）、清蛋白（albumin,Alb）、γ-谷氨酰转移酶（γ-glutamyltranspeptidase,γ-GT）、碱性磷酸酶（alkaline phosphatase,ALP）、总胆红素（total bilirubin,T-BIL)、甘油三酯（triglyceride,TG）、总胆固醇（total cholesterol,T-CHO）、低密度脂蛋白胆固醇（low density lipoprotein cholesterol,LDL-C）和高密度脂蛋白胆固醇（high density lipoprotein cholesterol,HDL-C）水平。蛋白免疫印迹法检测抑制性-κBα（inhibitory kappa B-alpha,I-κBα）蛋白表达水平和核转录因子（nuclear factor,NF）-κB p65磷酸化（p-NF-κB）水平。结果：LUFE干预能减轻肝组织的病理性损伤,抑制酒精所致的血清AST、ALT、γ-GT、ALP活力及TG、T-CHO、LDL-C、T-BIL水平的升高和Alb水平的降低,其中高剂量LUFE能达到显著抑制效果（P＜0.05,P＜0.01）。Western blot结果表明,与模型组相比,LUFE干预能提高I-κBα蛋白表达水平,抑制NF-κB p65蛋白的磷酸化,其中高剂量LUFE能达到显著改善效果（P＜0.05,P＜0.01）。结论：LUFE对酒精所致大鼠肝损伤有保护作用,其机制可能与其抗氧化、抗炎作用有关。     

Effects of sex, weight, diet and hCG administration on levels of skatole and indole in the liver and hepatic activities of cytochromes P4502E1 and P4502A6 in pigs

Cytochromes P4502E1 (CYP2E1) and P4502A6 (CYP2A6) catalyse metabolic reactions of skatole and indole metabolism. The objectives of this study were as follows: to evaluate whether activities of CYP2E1 and CYP2A6 in pigs of two live weights (LW) differ between males and females; to investigate whether activities of CYP2E1 and CYP2A6 are affected by hCG stimulation; and to investigate whether the levels of skatole and indole in the liver and the activities of CYP2E1 and CYP2A6 are affected by raw potato starch (RPS). Female pigs expressed higher CYP2A6 activity at 90kg LW, and higher CYP2E1 activity at 115kg LW compared to male pigs. Skatole levels in the liver were higher in male pigs than in female pigs at both LW, whereas indole levels were higher in males only at 115 kg LW. Neither levels of indolic compounds in the liver nor enzyme activities were affected by hCG stimulation. The inclusion of RPS in the diet reduced skatole levels in the liver in both sexes and increased CYP2A6 activity in female pigs. It was concluded that the incidence of boar taint may depend on both skatole amount, which reach the liver, and the activities of enzymes involved in skatole metabolism, which may vary depending on sex, live weight, and diet.     

肌肽联合超高压对黑鱼肉脂质氧化及肌原纤维蛋白的影响

为研究肌肽联合超高压(CUH)对黑鱼肉脂质氧化及肌原纤维蛋白(myofibrillar protein,MP)的影响,以新鲜宰后黑鱼肉为材料,比较分析CUH(肌肽浓度25 mmol/L,超高压压力300 MPa,保压时间900 s)处理对黑鱼肉在冷藏期间的脂质氧化、蛋白氧化、蛋白降解、蛋白结构等的影响.通过测定超高压后...     

绿原酸保护由脂多糖诱导引起的大鼠慢性肝脏损伤

本文采用脂多糖诱导建立大鼠慢性肝脏损伤模型,研究了绿原酸对大鼠慢性肝脏损伤的保护作用。将成年SD大鼠随机分LPS模型组和绿原酸干预组,实验持续28 d后进行取样。记录大鼠的生长性能和肝脏重量,并计算肝脏指数;检测血清中谷丙转氨酶(ALT)、谷草转氨酶(AST)、碱性磷酸酶(ALP)活性和总胆红素(TBIL)、总蛋白(TP)含量;HE染色观察肝组织病理变化;检测肝脏组织中超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量。结果表明,绿原酸能够显著降低慢性肝脏损伤大鼠的末重、平均日增重和食物转化率(P0.05);显著降低大鼠肝脏重量和肝脏指数(P0.05);显著降低血清中ALT、AST、ALP活性和TBIL含量(P0.05或P0.01),降幅分别为12%、13%、17%和50%;显著升高血清中TP含量和肝脏组织中SOD活性(P0.01或P0.05),增幅分别为17%和23%;显著降低肝脏组织中MDA含量(P0.05),降幅为33%;绿原酸能够改善慢性肝脏损伤大鼠的肝组织结构。因此,绿原酸对长期脂多糖应激引起的大鼠慢性肝脏损伤有一定的保护作用。     

花生肽对四氯化碳致小鼠肝损伤的保护作用

研究花生肽对四氯化碳(CCl4)致小鼠急性肝损伤的保护作用。采用CCl4致小鼠肝损伤,测定血和肝组织匀浆的生化指标。花生肽组均能减轻CCl4致小鼠急性肝损伤,降低血清中丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)、乳酸脱氢酶(LDH)的升高,增加组织中超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-PX)活力。花生肽对四氯化碳致小鼠急性肝损伤均有明显的保护作用。     

黑枸杞花色苷对酒精性肝损伤的保护作用

研究黑枸杞花色苷(black wolfberry anthocyanins,BWA)对酒精性肝损伤的保护作用。将受试小鼠随机分为空白组、模型组、BWA低中高剂量组及阳性对照组,连续灌胃30 d后,除空白组外,均给予体积分数56%乙醇溶液16 m L/kg灌胃,建立急性酒精性肝损伤模型,在模型建立12 h后,脱臼处死,测定血清中谷丙转氨酶(Alanine aminotransferase,ALT)、谷草转氨酶(Aspartate transaminase,AST)活性及肿瘤坏死因子α(Tumor necrosis factor-α,TNF-α)、白细胞介素6(Interleukin-6,IL-6)水平,肝组织中丙二醛(Malonaldehyde,MDA)、还原型谷胱甘肽(Reduced glutathione,GSH)水平及超氧化物歧化酶(Superoxide Dismutase,SOD)活性。结果显示,BWA可显著降低血清中ALT、AST活性及TNF-α、IL-6水平(P0.05);降低肝组织中MDA水平(P0.05),提高SOD活性及GSH水平(P0.05)。BWA对酒精诱发的酒精性肝损伤具有较好的保护作用。     

鸡枞菌多糖对急性酒精肝损伤小鼠超微病理结构及ADH2、ALDH2 mRNA表达的影响

目的：从小鼠肝脏超微病理结构及酒精代谢相关酶乙醇脱氢酶2（alcohol dehydrogenase 2,ADH2）、乙醛脱氢酶2（aldehyde dehydrogenase 2,ALDH2）的mRNA表达方面研究鸡枞菌多糖（refined polysaccharidesfrom Termitomyces albuminosus,RPTA）对酒精所致小鼠急性肝损伤的保护作用。方法：小鼠被随机分为空白对照组、模型对照组、药物对照组（联苯双酯组,150 mg/（kg·d））、RPTA各剂量组（100、200、400 mg/（kg·d））,连续灌胃30 d,空白对照组灌胃等量生理盐水。第31天,给予50%乙醇（12 mL/kg）建立动物急性肝损伤模型。12 h后处死,取小鼠肝脏分别观察肝组织超微结构变化,并采用荧光实时定量聚合酶链式反应（real time polymerase chain reaction,real time-PCR）法检测肝脏ADH2和ALDH2的mRNA表达。结果：超微结构观察结果表明,模型对照组小鼠肝脏细胞内可见大量脂滴,细胞核呈不规则形态,局部核膜凹陷严重,线粒体严重变形,线粒体嵴模糊,内质网严重肿胀,核糖体脱落;而RPTA小鼠肝细胞内上述病变有所改善,尤以高剂量组最佳。Real time-PCR结果表明,与空白对照组相比,模型对照组ADH2和ALDH2的mRNA表达量降低,而RPTA组随着剂量的增加ADH2和ALDH2 mRNA的表达逐渐升高。结论：RPTA可以上调ADH2和ALDH2 mRNA的表达,具有改善小鼠酒精性肝损伤状况的作用。     

Protective effects of protein hydrolysate from marine microalgae Navicula incerta on ethanol-induced toxicity in HepG2/CYP2E1 cells

Ethanol is independently known to cause tissue damage through various mechanisms. This study was designed to evaluate the protective effect of marine microalgae, Navicula incerta protein enzymatic hydrolysates (NEHs) against ethanol-induced hepatotoxicity in HepG2 cells transfected with human CYP2E1. Induction of CYP2E1 by ethanol is one of the central pathways by which ethanol generates a state of oxidative stress in hepatocytes. When the alcohol-induced cells were treated with NEHs at various concentrations, there was a dose-dependent decrease of gamma-glutamyl transpeptidase (GGT) activity in the culture media and loss of cell viability. Among the NEHs constituents the hydrolysates which were obtained by papain (P-NEH), pronase-E (PR-NEH) and α-chymotrypsin (A-NEH) activity attenuated the ethanol cytotoxicity effectively, respectively. The activity appeared to be a GGT inhibitor. Therefore, the cytoprotective effects at alcohol-induced HepG2/CYP2E1 cells could be attributed to the inhibition of GGT activity by NEHs. This study suggests that NEHs have enough potential to be considered as highly active compounds against ethanol toxicity which leads NEHs to be significant nutraceuticals.     

白桦脂酸与红枣总三萜酸对小鼠酒精肝损伤的保护作用

为研究白桦脂酸与红枣总三萜酸对小鼠酒精肝损伤的保护作用,通过白酒灌胃小鼠建立酒精性肝损伤模 型,测定小鼠体质量、肝脏指数及相关生化指标,并取肝脏制作苏木精-伊红染色切片,观测肝组织的病理学变 化。结果表明,白桦脂酸与红枣总三萜酸均可降低酒精性肝损伤小鼠肝脏指数、血清谷丙转氨酶和谷草转氨酶活力 以及甘油三酯、总胆固醇、低密度脂蛋白胆固醇水平,显著提高高密度脂蛋白胆固醇水平、肝脏谷胱甘肽过氧化物 酶、超氧化物歧化酶活力（P＜0.05）,同时使肝脏丙二醛水平显著下降（P＜0.05）,肝组织病理损伤也得到明显 改善。白桦脂酸和红枣总三萜酸对酒精性肝损伤具有明显保护作用。     

赤红球菌组氨酸激酶的融合表达和功能分析

对赤红球菌的组氨酸激酶基因进行密码子优化,将优化后的组氨酸激酶基因（rhks）构建重组表达质粒pGEX-4T-2-rhks。将此质粒导入到大肠杆菌BL21（DE3）中进行异源表达。在25 ℃和1 mmol/L异丙基-β-D-硫代吡喃半乳糖苷诱导条件下,组氨酸激酶融合蛋白（GST-RHK）获得成功表达,并具有催化活性。经谷胱甘肽琼脂糖亲和层析纯化,获得电泳纯的GST-RHK,其中纯化倍数为3.1,得率为19.5%。该蛋白大小约为72.75 kDa,Km、Vmax和Kcat值分别为20.92 μmol/L、0.17 μmol/（L·min）和1.4 min－1。野生型赤红球菌、组氨酸激酶基因增强株sdrhkE和组氨酸激酶基因敲减株sdrhkD在分别含有苯酚、甲苯、氯苯、异辛烷4 种有机溶剂的培养基中培养,菌株sdrhkD的生长情况都优于野生型赤红球菌,菌株sdrhkE的生长情况都低于野生型赤红球菌。本研究为进一步揭示赤红球菌SD3中组氨酸激酶涉及的信号转导途径与赤红球菌有机溶剂耐受性的关联机制提供一定参考依据。     

Aqueous Extract of Gynura Bicolor Attenuated Hepatic Steatosis,Glycative, Oxidative,and Inflammatory Injury Induced by Chronic Ethanol Consumption in Mice

Gynura bicolor leaf aqueous extract (GAE) is rich in phytochemicals including phenolic acids, flavonoids, carotenoids, and anthocyanins. Effects of GAE upon hepatic injury in mice with chronic ethanol intake were examined. Lieber–DeCarli liquid diet with ethanol was used to induce hepatic lipid accumulation, oxidative, glycative, and inflammatory injury. GAE at 0.25% or 0.5% was added in feeds, and supplied to mice consumed Lieber–DeCarli liquid diet with ethanol for 6 wk. Blood and liver were collected for analyses. Results showed that ethanol increased plasma and hepatic triglyceride and cholesterol content, and affected plasma levels of insulin, adiponectin, leptin, and ghrelin. GAE at both doses decreased lipid accumulation, and at high dose improved hormones abnormality. Histological data revealed that GAE supplement mitigated hepatic lipid deposit. Ethanol increased plasma N^ε‐(carboxyethymethyl)‐lysine and pentosidine levels. GAE at high doses lowered those glycative factors. Ethanol depleted glutathione content, increased CYP2E1 activity and reactive oxygen species production, and reduced the activity of glutathione peroxide, glutathione reductase and catalase in liver. GAE supplement at both doses reversed these alterations and attenuated hepatic oxidative stress. GAE supplement also at both doses decreased hepatic inflammatory cytokines release in ethanol treated mice. These findings support that leaves of G. bicolor is a functional food with liver protective activities against ethanol.