糖脂代谢在溃疡性结肠炎中的调控机制及药物干预进展

溃疡性结肠炎作为一种炎症性肠病,其病程漫长且容易反复发作,严重影响患者的生活质量。糖脂代谢在维持机体稳态方面有着重要的作用,而糖脂代谢的异常变化往往会导致溃疡性结肠炎的发生和发展。近年来,越来越多的研究聚焦于结肠炎中糖脂代谢的变化,并发现调控糖脂代谢的药物可以改善结肠炎,靶向糖脂代谢可能成为溃疡性结肠炎治疗的新策略。就糖脂代谢在溃疡性结肠炎的调控机制及药物干预的进展做总结、分析和综述,以期为溃疡性结肠炎的防治提供新的思路。

Overexpression of sterol carrier protein-2 mRNA in patients with cholesterol gallstones

BACKGROUND: Hypersecretion of biliary cholesterol is believed to be one of the important causes of lithogenic bile. Sterol carrier protein-2 ( SCP2 ) participates in choles- terol trafficking and metabolism and may play a key role in cholesterol gallstone formation. This study was undertaken to investigate the expression of liver SCP2 mRNA in pa- tients with cholesterol gallstone and those patients with non-cholesterol gallstone. METHODS: The expression of liver SCP2 mRNA was studi- ed in 36 patients with cholesterol gallstone and 30 patients with non-cholesterol gallstone by reverse transcription-poly- merase chain reaction (RT-PCR). RESULT: The expression of SCP2 mRNA was increased more significantly in patients with cholesterol gallstone than in patients with non-cholesterol gallstone. CONCLUSION: The SCP2 gene was overexpressed in pa- tients with cholesterol gallstone, indicating that SCP2 may be one of the important causes of cholesterol gallstone.

Red Yeast Rice Increases Excretion of Bile Acids in Hamsters

Objective To investigate the hypocholesterolemic activity of red yeast rice （RYR） and its underlying mechanism. Methods Three groups of hamsters were fed either the control diet or one of the two experimental diets containing by weight 0.1% RYR （0.1RYR） or 0.3% RYR （0.3RYR）. Blood （0.5 mL） was collected from the retro-orbital sinus into a heparinized capillary tube at the end of week 0, 3, and 6. Plasma lipoproteins were measured using enzymatic kits, while fecal neutral and acidic sterols were quantified using a gas-liquid chromatography. Results Plasma total cholesterol was reduced by 12% in 0.1RYR group and by 18% in 0.3RYR group compared with the control value. Similarly, plasma triacylglycerol was decreased by 11% in 0.1RYR group and by 24% in 0.3RYR group. Western blotting analysis demonstrated that RYR had no effect on sterol regulatory element binding protein 2, fiver X receptor, 3-hydroxy-3-methylglutary-CoA reductase, LDL receptor, and cholesterol-7α-hydroxylase. HPLC analysis confirmed that RYR contained 0.88% monacolin K. It was recently found that RYR supplementation increased excretion of fecal acidic sterols by 34 folds compared with the conlrol value. Conclusion Hypocholesterolemic activity of RYR is mediated at least partially by enhancement of acidic sterol excretion.

Biliary cholesterol secretion: More than a simple ABC

Biliary cholesterol secretion is a process important for 2 major disease complexes, atherosclerotic cardiovascular disease and cholesterol gallstone disease. With respect to cardiovascular disease, biliary cholesterol secretion is regarded as the f inal step for the elimination of cholesterol originating from cholesterol-laden macrophage foam cells in the vessel wall in a pathway named reverse cholesterol transport. On the other hand, cholesterol hypersecretion into the bile is considered the main pathophysiological determinant of cholesterol gallstone formation. This review summarizes current knowledge on the origins of cholesterol secreted into the bile as well as the relevant processes and transporters involved. Next to the established ATP-binding cassette (ABC) transporters mediating the biliary secretion of bile acids (ABCB11), phospholipids (ABCB4) and cholesterol (ABCG5/G8), special attention is given to emerging proteins that modulate or mediate biliary cholesterol secretion. In this regard, the potential impact of the phosphatidylserine flippase ATPase class Ⅰ type 8B member 1, the Niemann Pick C1-like protein 1 that mediatescholesterol absorption and the high density lipoprotein cholesterol uptake receptor, scavenger receptor class B type Ⅰ, is discussed.

A new framework for reverse cholesterol transport: Non-biliary contributions to reverse cholesterol transport

Reduction of low-density lipoprotein-cholesterol through statin therapy has only modestly decreased coronary heart disease (CHD)-associated mortality in developed countries, which has prompted the search for alternative therapeutic strategies for CHD. Major efforts are now focused on therapies that augment high-density lipoprotein (HDL)-mediated reverse cholesterol transport (RCT), and ultimately increase the fecal disposal of cholesterol. The process of RCT has long been thought to simply involve HDL-mediated delivery of peripheral cholesterol to the liver for biliary excretion out of the body. However, recent studies have revealed a novel pathway for RCT that does not rely on biliary secretion. This nonbiliary pathway rather involves the direct excretion of cholesterol by the proximal small intestine. Compared to RCT therapies that augment biliary sterol loss, modulation of non-biliary fecal sterol loss through the intestine is a much more attractive therapeutic strategy, given that excessive biliary cholesterol secretion can promote gallstone formation. However, we are at an early stage in understanding the molecular mechanisms regulating the non-biliary pathway for RCT, and much additional work is required in order to effectively target this pathway for CHD prevention. The purpose of this review is to discuss our current understanding of biliary and nonbiliary contributions to RCT with particular emphasis on the possibility of targeting the intestine as an inducible cholesterol secretory organ.

Meta-analysis reveals up-regulation of cholesterol processes in non-alcoholic and down-regulation in alcoholic fatty liver disease

AIM To compare transcriptomes of non-alcoholic fatty liver disease(NAFLD) and alcoholic liver disease(ALD) in a meta-analysis of liver biopsies.METHODS Employing transcriptome data from patient liver biopsies retrieved from several public repositories we performed a meta-analysis comparing ALD and NAFLD.RESULTS We observed predominating commonalities at the transcriptome level between ALD and NAFLD,most prominently numerous down-regulated metabolic pathways and cytochrome-related pathways and a few up-regulated pathways which include ECM-receptor interaction,phagosome and lysosome.However some pathways were regulated in opposite directions in ALD and NAFLD,for example,glycolysis was down-regulated in ALD and up-regulated in NAFLD.Interestingly,we found rate-limiting genes such as HMGCR,SQLE and CYP7A1 which are associated with cholesterol processes adversely regulated between ALD(down-regulated) and NAFLD(up-regulated).We propose that similar phenotypes in both diseases may be due to a lower level of the enzyme CYP7A1 compared to the cholesterol synthesis enzymes HMGCR and SQLE.Additionally,we provide a compendium of comparative KEGG pathways regulation in ALD and NAFLD.CONCLUSION Our finding of adversely regulated cholesterol processes in ALD and NAFLD draws the focus to regulation of cholesterol secretion into bile.Thus,it will be interesting to further investigate CYP7A1-mediated cholesterol secretion into bile-also as possible drug targets.The list of potential novel biomarkers may assist differential diagnosis of ALD and NAFLD.

A comparative study of changing patterns of concanavalin A-binding proteins in early stage of cholesterol gallstone

IM To elucidate the importance and the changing patterns of biliary concanavalin Abinding proteins (CPs) in the early stage of cholesterol gallstone.METHODS CPs concentrations and nucleation activities were measured by lectin affinity chromatography in biles of patients with cholesterol gallstone, pigment gallstone, gallbladder cholesterosis and nonbiliary diseases.RESULTS The concentrations of CPs were much higher in patients with cholesterol gallstone (039g/L±011g/L, n=36, P<001) or gallbladder cholesterosis (040g/L±009g/L, n=9, P<001) than in those with pigment gallstone (026g/L±012g/L, n=7) and/or nonbiliary diseases (027g/L±009g/L, n=10). Pronucleating activities were much stronger in patients with cholesterol gallstones (nucleation time ratio: 057±021, n=5, P<001 vs pigment gallstone and/or nonbiliary diseases) and gallbladder cholesterosis (nucleation time ratio: 044±023, n=5, P<001 vs pigment gallstone or nonbilliary diseases). The binding percentages of CPs to model biliary vesicles were also higher in patients with cholesterol gallstones (n=6) than those with pigment gallstones (n=6) (24%±09% vs 09%±05%, P<001).CONCLUSION Hypersecretion of CPs, especially those in vesicular phase may be the important changes in the early stage of cholesterol gallstone.

Hepatobiliary membrane transporters involving in the formation of cholesterol calculus

BACKGROUND: Cholecyst cholesterol lithiasis is a common disease of the digestive system; however, the cause of lithogenesis is still unclear. Although bile salt export pump (BSEP), multidrug resistance protein 2 (MRP2), and multiple drug resistance 3 (MDR3 ) are 3 well-known transporting proteins, their effect on lithogenesis has not been elucidated. This study was undertaken to examine the relationship between BSEP, MRP2, MDR3, and cholesterol calculus formation. METHODS: Liver tissue specimens were taken from 20 patients with cholesterol calculus and from 10 patients with normal liver. mRNA and protein expressions of BSEP, MRP2, and MDR3 were determined by reverse tran-scriptase-polymerase chain reaction (RT-PCR) and Western blot, respectively. This study was approved by the ethics committee of China Medical University and informed consent was obtained from all patients. RESULTS: mRNA and protein expressions of BSEP, MRP2, and MDR3 were significantly down-regulated in the liver tissue of the patients with cholesterol calculus compared with normal liver tissue of the controls. CONCLUSION: The down-regulation of BSEP, MRP2, and MDR3 may be correlated with the formation of cholesterol calculus.

Bile acid formation in primary human hepatocytes

AIM To evaluate a culture system for bile acidformation in primary human hepatocytes incomparison with HepG2 cells.METHODS Hepatocytes were isolated fromnormal human liver tissue and were cultured inserum-free William’s E medium.The medium wascollected and renewed every 24 h.Bile acids andtheir precursors in media were finally analysed bygas chromatography-mass spectrometry.RESULTS Cholic acid(CA)andchenodeoxycholic acid(CDCA)conjugated withglycine or taurine accounted for 70% and 25% oftotal steroids.A third of CDCA was alsoconjugated with sulphuric acid.Dexamethasoneand thyroid hormone alone or in combination didnot significantly effect bile acid formation.Theaddition of cyclosporin A(10 μmol/L)inhibited thesynthesis of CA and CDCA by about 13% and30%,respectively.CONCLUSION Isolated human hepatocytes inprimary culture behave as in the intact liver byconverting cholesterol to conjugated CA andCDCA.This is in contrast to cultured HepG2 cells,which release large amounts of bile acidprecursors and unconjugated bile acids into themedium.

Effects of lactic acid bacteria isolated from fermented mustard on lowering cholesterol

Objective:To evaluate the ability of lactic acid bacteria(LAB)strains isolated from fermented mustard to lower the cholesterol in vitro.Methods:The ability of 50 LAB strains isolated from fermented mustard on lowering cholesterol in vitro was determined by modified o-phtshalaldehyde method.The LAB isolates were analyzed for their resistance to acid and bile salt.Strains with lowering cholesterol activity,were determined adherence to Caco-2 cells.Results:Strain B0007,B0006 and B0022 assimilated more cholesterol than BCRC10474 and BCRC17010.The isolated strains showed tolerance to pH 3.0 for 3h despite variations in the degree of viability and bile-tolerant strains,with more than 10~s CFU/mL after incubation for 24 h at 1%oxigall in MRS.In addition,strain B0007 and B0022 identified as Lactobacillus plantarum with 16S rDNA sequences were able to adhere to the Caco-2 cell lines.Conclusions:These strains B0007 and B0022 may be potential functional sources for cholesterollowering activities as well as adhering to Caco-2 cell lines.

Gender May Affect the Dose-Dependent Action of Capsaicinoids on Plasma and Hepatic Cholesterol Levels of Rats

Sex differences on the effect of dose-dependent capsaicinoids on lipid metabolism were studied in rats. 24 rats of each sex were administered orally 0 mg/kg, 2.5 mg/kg, 5 mg/kg or 7.5 mg/kg capsaicinoids daily for 28 days. In male rats, body weight gained, and the levels of total lipids, total cholesterol and triglycerides in the liver were significantly decreased as the dose of capsaicinoids increased. On the other hand, plasma total cholesterol (TC), triglycerides (TG), HDL- and LDL-cholesterol concentration and liver weight were not affected by capsaicinoids. While in female rats, plasma TC, TG, HDL-C and LDL-C concentration, liver total lipids, TC and TG concentration were significantly decreased as the dose of capsaicinoids increased. The mRNA level of hepatic TRPV1, ileac ASBT and IBABP were increased as the dose of capsaicinoids increased in all rats groups. The mRNA level of hepatic HMG-CoA reductase, CYP7A1 and FXR were significantly decreased in female rats groups. These results show that the hypocholesterolemic effect of capsaicinoids in dose-dependent manner in rats was mediated by inhibited synthesis of endogenous cholesterol, female rats were more sensitive than male rats on hypolipidemic effect of capsaicinoids.

Symbiotic, Hypocholesterolemic and Antioxidant Effects of Potential Probiotic Lactobacilli Strains Isolated from Tunisian Camel Milk

In the present study, 20 selected Lactobacillus strains already characterized in a previous research for their capability to grow in conditions simulating the intestinal environment, their resistance to antibiotics, their antibacterial activity and their adhesion capability to intestinal human Caco-2 TC7 and HT-29 MTX cell lines, were further investigated to explore more their probiotic properties. Growth behaviour in the presence of prebiotic (fructooligosac-charides (FOS) and lactulose) at a concentration of 2%, cholesterol removal by measuring the residual cholesterol in medium supplemented with cholesterol, ability to deconjugate bile salts using BSH enzyme and antioxidant activity of culture supernatant of Lactobacillus strains by ABTS·+ and DPPH methods were analyzed. All probiotic strains demonstrated important prebiotic assimilation (P > 0.05) even with OD600 > 3 after 30 h of contact, cholesterol removal ability with maximum percentage of 57% after 24 h of contact and they were found to liberate significantly (P < 0.05) more cholic acid with maximum of 0.40 mM of sodium glycocholate, 0.33 mM of sodium taurocholate and 0.41 mM of their mixte and scavenge both radicals with 52% and 2.19% of ABTS·+ and DPPH respectively. This study confirmed the suitability of these probiotic strains for application in functional food formulations especially where cholesterol reduction and antioxidant activity in food are needed to assess possible in vivo human health benefits.

绿原酸对高游离脂肪酸处理犊牛肝细胞胆固醇和胆汁酸代谢的影响

【目的】探究绿原酸(CGA)对高游离脂肪酸(FFA)处理的犊牛肝细胞胆固醇和胆汁酸代谢的影响。【方法】采用两步胶原酶灌注法分离犊牛原代肝细胞,利用免疫荧光鉴定细胞后将其分为4组,对照组细胞用含2%BSA的RPMI-1640培养基培养;FFA组细胞在含2%BSA的RPMI-1640培养基中添加1.2 mmol/L FFA后培养;CGA组细胞在含2%BSA的RPMI-1640培养基中添加20μg/mL CGA后培养;CGA+FFA组细胞在含2%BSA的RPMI-1640培养基中添加1.2 mmol/L FFA和20μg/mL CGA后培养。培养12 h后收集细胞,通过试剂盒检测细胞中甘油三酯(TAG)和总胆固醇(TC)含量;利用实时荧光定量PCR、Western blotting分别检测肝细胞中胆固醇合成相关因子甾醇调节元件结合转录因子2(SREBF2)、3-羟基-3-甲基戊二酰辅酶A还原酶(HMGCR),胆固醇外排相关因子乙酰辅酶A乙酰转移酶2(ACAT2)、ATP结合盒亚家族A成员1(ABCA1)、ATP结合盒亚家族G成员5(ABCG5)以及胆汁酸代谢相关因子胆固醇7α-羟化酶(CYP7A1)、胆固醇12α-羟化酶(CYP8B1)、胆固醇27α-羟化酶(CYP27A1)、法尼醇X受体(FXR)、成纤维细胞生长因子受体4(FGFR4)等因子的mRNA和蛋白表达水平。【结果】犊牛肝细胞经过不同处理后,与对照组相比,FFA组犊牛肝细胞中TC含量极显著降低(P<0.01),TAG含量极显著升高(P<0.01),HMGCR、ABCA1、ABCG5、ABCG8、APOA1、ACAT1、NPC1L1、FXR、FGFR4基因mRNA表达量和SREBF2、ACAT2、ABCA1、ABCG5蛋白表达量均极显著或显著降低(P<0.01;P<0.05),CYP8B1基因mRNA表达量和CYP7A1、CYP8B1蛋白表达量均极显著或显著升高(P<0.01;P<0.05);CGA组犊牛肝细胞中TC含量极显著升高(P<0.01),SREBF2、ABCA1、CYP27A1、FXR、FGFR4蛋白表达量均极显著升高(P<0.01),CYP7A1蛋白表达量极显著降低(P<0.01)。与FFA组相比,CGA+FFA组犊牛肝细胞中TC含量显著升高(P<0.05),TAG含量显著降低(P<0.05),HMGCR、ACAT2、ABCA1、ABCG5、APOA1基因mRNA表达量和SREBF2、ACAT2、ABCA1、ABCG5、FXR、FGFR4蛋白表达量均极显著或显著升高(P<0.01;P<0.05),CYP7A1、CYP8B1蛋白表达量均极显著降低(P<0.01)。【结论】CGA能参与调节犊牛肝细胞内胆固醇稳态,同时激活FXR和FGFR4,进而缓解高FFA处理的犊牛肝细胞胆汁酸蓄积。

健脾祛痰方干预血脂异常临床疗效及对肠道菌群的影响

目的通过观察健脾祛痰方对脾虚痰浊型血脂异常患者的血脂水平、中医证候积分的影响,分析正常与高脂人群、中药治疗前后患者肠道菌群的结构变化,以明确健脾祛痰方降脂的临床疗效,探索健脾祛痰法降脂的作用机制。方法在辽宁中医药大学附属医院纳入正常及脾虚痰浊血脂异常受试者共计180例,按照就诊顺序随机分为正常组、模型组、健脾祛痰方组,每组60例。所有组别均予健康宣教,健脾祛痰方组予健脾祛痰方颗粒剂冲服,治疗疗程为2个月。采用全自动分析仪检测所有受试者血清胆固醇(Total Cholesterol,TC)、甘油三酯(Triglyceride,TG)、低密度脂蛋白胆固醇(Low Density Lipoprotein,LDL-C)、高密度脂蛋白胆固醇(High Density Lipoprotein,HDL-C)水平,用中医证候积分量表评定患者中医证候疗效,酶联免疫吸附测定法测定受试者血清人成纤维细胞生长因子19(FGF19)的表达水平,16SrRNA高通量测序技术检测受试者粪便标本肠道菌群的结构变化。结果脾虚痰浊型血脂异常患者经健脾祛痰方治疗后血脂水平,中医证候积分较治疗前明显改善,血清中FGF19含量明显降低;健脾祛痰方组血脂疗效、中医证候积分总有效率显著优于模型组。高脂人群菌群多样性和物种丰度与正常人群相比明显减弱。有益菌减少,肠杆菌过生长,肠道菌群结构被破坏。健脾祛痰方组患者用药后样本间差异明显,各分类水平物种组成比例发生变化,编码胆盐水解酶(Bile Salt Hydrolase,BSH)相关微生物丰度降低。用药后肠道中的有害菌肠杆菌目(Enterobacteriales)减少,肠道菌群平衡有所恢复。结论健脾祛痰法能够显著降低血脂异常患者TC、TG、LDL-C水平,改善中医证候,其机制可能通过调节肠道菌群和胆汁酸代谢抑制FXR信号传导通路以降脂。

基于FXR-FGF19通路研究益生菌对胆总管结石患者胆汁酸代谢的影响

背景:胆总管结石在取石术后有较高的复发率。近年研究表明肠道微生态失衡与胆固醇结石的形成有关。目的:探究益生菌干预对胆固醇结石高危人群血清脂多糖(LPS)以及胆汁酸代谢指标的影响。方法:选取2021年6月—2023年6月在石河子大学第一附属医院行ERCP取石术的胆总管结石患者60例,收集胆汁和粪便样本行细菌培养。将患者随机分为对照组和益生菌干预组,对照组取石术后予常规支持治疗,干预组在常规治疗的基础上服用双歧杆菌三联活菌肠溶胶囊420 mg,每日2次,连续6个月。检测治疗前后革兰阴性菌细胞壁成分LPS、胆汁酸代谢关键分子成纤维细胞生长因子19(FGF19)和胆汁酸合成限速酶胆固醇7α-羟化酶(CYP7A1)血清水平的变化。结果:胆总管结石患者胆汁、粪便细菌培养显示主要致病菌为大肠埃希菌和肺炎克雷伯菌。ERCP取石术后6个月,患者血清LPS、FGF19水平明显降低,CYP7A1水平明显升高(P均<0.05),益生菌干预组数据变化较对照组更为显著(P均<0.05)。结论:口服益生菌制剂可降低胆固醇结石高危人群的血清LPS水平,同时调节胆汁酸经肠肝循环代谢的经典通路法尼酯X受体(FXR)-FGF19通路,从而减少胆汁中的胆固醇过饱和,降低胆固醇结石的形成概率。

胆固醇类结石患者血脂水平和胆汁成分对其术后结石复发的预测价值分析

目的:探讨胆固醇类结石患者血脂水平和胆汁成分对其术后结石复发的预测价值。方法:选取39例行手术治疗后再复发的胆固醇类结石患者为复发组,另选取同期收治78例术后未复发胆固醇类结石患者为未复发组,比较两组患者血脂水平和胆汁成分变化,受试者特征曲线分析血脂水平和胆汁成分对胆固醇类结石患者术后复发的预测价值,分析胆固醇类结石患者术后复发危险因素。结果:复发组BMI≥28kg/m2、结石数量≥2枚患者占比分别为48.72%、74.36%,均高于未复发组的29.49%、53.85%(均P<0.05)。复发组患者总胆固醇(TC)、甘油三酯(TG)水平和胆汁胆固醇(CHO)高于未复发组(均P<0.05)。受试者特征曲线分析显示血TC、TG、胆汁CHO水平及其联合检测对术后结石复发的曲线下面积分别为0.711、0.718、0.727、0.871,联合检测的曲线下面积高于其单独检测(均P<0.05)。多因素Logistic回归分析显示TC>4.850mmol/L、TG>1.455mmol/L、胆汁CHO>96.975mmol/L、BMI≥28kg/m2、结石数量≥2枚是胆固醇类结石患者术后结石复发危险因素(均P<0.05)。结论:TC、TG、胆汁CHO水平联合检测能提高胆固醇类结石患者术后结石复发预测价值,其水平异常升高、肥胖和结石数量多会增加术后结石复发风险。

柿单宁的体外降胆固醇作用

采用分光光度法和气相色谱法研究了柿单宁对胰脂酶活性和胆固醇酯酶活性的抑制作用,以及柿单宁与胆汁酸、胆固醇的结合能力。结果表明:柿单宁对胰脂酶具有显著的抑制效果,其半数抑制浓度(half inhibitory concentration,IC50)为(0.445±0.021)mg/m L;抑制类型为非竞争性抑制,抑制常数Ki为0.406 mg/m L;柿单宁对胆固醇酯酶也具有显著的抑制作用,其半数抑制浓度IC50为(0.442±0.017)mg/m L,抑制类型为非竞争性抑制,抑制常数Ki为0.488 mg/m L。不同质量浓度的柿单宁对胆酸(cholic acid,CA)、脱氧胆酸(deoxycholic acid,DCA)都有一定的结合能力,10 mg/m L的单宁与CA、DCA的结合率分别为58%和94%;柿单宁对胆固醇胶束化溶液有较强的结合能力,0.20 mg/m L的单宁对其抑制率达到了67%。另外,在不同的p H值下,柿单宁对胆固醇都有一定的结合作用,其中p H 7.0时的结合能力明显强于p H 2.0时的结合能力。总之,柿单宁可抑制胰脂酶活性和胆固醇酯酶活性,并与胆固醇和胆汁酸结合,减少胃肠道对脂肪的吸收,这可能是柿单宁在体内发挥强降胆固醇作用的原因之一。

胆汁酸受体FXR的研究进展

法尼酯衍生物X受体 (FXR)是一种胆汁酸受体 ,在胆汁酸代谢和胆固醇代谢中发挥重要作用 ,并有望成为降低胆固醇 ,治疗某些心血管病及肝脏疾病的治疗靶点。本文介绍了FXR的发现、FXR在调控胆汁酸和脂质代谢中的作用 ,以及FXR在心血管疾病治疗中的应用前景。

芋头多糖提取工艺优化及其体外结合脂类和胆酸盐能力研究

以新鲜龙香芋为原料,对其水溶性多糖的水溶醇沉提取工艺进行优化,并通过体外模拟人体胃肠消化环境,测定其对脂肪、胆固醇、胆酸盐的结合能力,考察芋头多糖的体外降脂效果。结果表明,当提取温度80℃、提取时间6h、料液比1∶6(g/mL)、乙醇体积分数85%时,芋头多糖提取效果最好,提取率达(4.92±0.18)%。芋头多糖经过胃肠消化系统后,对脂肪和胆酸盐的吸附效果优于对照纤维素,对两者的结合能力与其质量浓度呈现显著相关性;对胆固醇的吸附效果低于纤维素,表明芋头多糖具有一定的降脂功能,降脂机理与纤维素不同。

耐胆酸盐、降胆固醇乳酸菌的筛选

从乳酸发酵制品和发酵菌剂中分离纯化获得了25株菌,通过显微镜形态观察、革兰氏染色反应和石蕊牛奶试验证实其中10株为乳酸菌。进一步比较了这些菌株和Streptococcusthermophilis,Lactobaccillusbulgaricus的胆酸盐耐受能力以及对牛奶中胆固醇的作用效果。结果表明,多数乳酸菌可耐受低质量分数(0.1%)的胆酸盐,可以不同程度的降低牛奶中的胆固醇含量;但在含有质量分数为0.3%胆酸盐时,只有少数乳酸菌对牛奶中降胆固醇的能力有所提高。