乳酸菌SK1.002产L-阿拉伯糖异构酶培养基优化及发酵条件

L-阿拉伯糖异构酶能将D-半乳糖异构成D-塔格糖。通过单因素试验和快速登高法对乳酸菌SK1.002产L-阿拉伯糖异构酶的培养基进行优化,确定发酵优化条件为（组分g/L）：麦芽糊精28,酵母膏10,玉米粉浆22,无水乙酸钠10,K3PO40.2,NaCl 0.01,FeSO4.7H2O 0.01,Mg-SO4.7H2O 0.2,MnSO4.2H2O 0.05,L-阿拉伯糖2.5。发酵初始pH 8.4,培养温度37℃,接种体积分数3%,培养时间12 h。在此发酵条件下,酶活达到了7.28 U/mL。     

L-阿拉伯糖对2型糖尿病大鼠糖脂代谢的影响

目的探讨L-阿拉伯糖对2型糖尿病模型大鼠血糖、血脂、脏器及胰岛的影响。方法采用雄性Wistar大鼠高糖高脂饲料喂养8周后,按25mg/kgbw的剂量一次性腹腔注射链脲佐菌素建立2型糖尿病动物模型,按L-阿拉伯糖低剂量(50mg/kgbw)、中剂量(150mg/kgbw)及高剂量(500mg/kgbw)进行灌胃,以阿卡波糖(20mg/kgbw)作为阳性对照,所用L-阿拉伯糖及阿卡波糖均配制于糊精(0.36g/ml)与蔗糖(0.04g/ml)的悬浮液中,自由进食进水。给药4周后进行口服葡萄糖耐量试验,处死后对大鼠肝脏、附睾脂肪及盲肠进行称重,腹主动脉取血测定TC、TG、血糖及胰岛素水平,通过免疫组织化学切片对胰岛β细胞损伤程度进行评价。结果与模型组对比,低、中、高剂量的L-阿拉伯糖干预对糖尿病大鼠的血糖应答产生了显著影响,30、60和120min血糖值及AUC均显著低于模型对照组(P<0.05),其中以中剂量效果最为显著(P<0.01)。L-阿拉伯糖的干预对糖尿病大鼠胰岛素敏感性的改善未见显著,但增加了盲肠重量,对胰岛β细胞也呈现出保护作用。本研究中L-阿拉伯糖的干预对于血脂和血胆固醇的影响较小。结论 L-阿拉伯糖的中长期干预能够改善2型糖尿病大鼠的糖耐量,这种作用可能与L-阿拉伯糖对食物消化酶的抑制及对胰岛β细胞的保护作用相关。     

L-阿拉伯糖对胰岛素抵抗大鼠降糖作用的研究

目的研究L-阿拉伯糖(L-arabinose,L-A)对胰岛素抵抗大鼠的降血糖作用及其机制。方法提取大鼠小肠α-葡萄糖苷酶,分别以蔗糖(sucrose,S)、麦芽糖(maltose,M)和α-糊精(α-dextrin,α-D)为底物,体外测定L-A的α-葡萄糖苷酶抑制活性;建立胰岛素抵抗大鼠模型,分别给与葡萄糖(glucose,G)/S(2 g/kg bw)+L-A(mg/kg bw)0、50、100、250;G/S(1.75 g/kg bw)+250 mg/kg bw L-A及单纯L-A(2g/kg bw)灌胃,测定0、30、60、120 min血糖水平变化,并计算各时间点血糖水平抑制率及血糖应答曲线下面积(AUC)抑制率。以阿卡波糖(acarbose,Acar)为阳性对照。结果 L-A体外可抑制小肠α-葡萄糖苷酶活性,尤其选择性较强地抑制蔗糖酶活性,当其添加量为0.5%S含量时,酶活抑制率>50%,最高抑制率为93%左右,有良好剂量反应关系,IC50为0.164 mg/ml;动物实验中,L-A对口服G后引起的血糖应答无影响(P>0.05),对于口服S后的血糖水平升高有良好抑制作用且有一定剂量反应关系,低、中、高剂量L-A对灌胃S后30min血糖抑制率分别为(20.9±14.1)%,(26.8±16.1)%,(27.5±24.9)%,AUC抑制率分别为(13.9±9.7)%,(15.4±12.1)%,(22.2±16.9)%,当只摄入L-A时,餐后血糖水平变化较小。以阿卡波糖(Acarbose,Acar)为阳性对照。结论 L-A可选择性抑制小肠蔗糖酶活性,对口服S后的血糖升高有良好抑制作用,推测选择性抑制小肠蔗糖酶活性以利于摄入S后血糖水平的控制为其降血糖机制之一,在肥胖、糖尿病等预防中具有积极意义。[营养学报,2012,34(6):563-566,571]     

Direct-acting mutagenic activity in white, rosé, and red wines with the Ara test of Salmonella typhimurium.

Thirty-two commercially produced white, rosé, and red wines from Spain were assayed for genotoxicity. The Ara forward mutagenicity assay with Salmonella typhimurium served as the test system. All the wines were mutagenic in the absence of mammalian microsomal activation (S9 mix) and/or glycosidase activities with the exception of one rosé wine which gave a clear dose-response relationship, although its mutagenic potency was considered statistically nonsignificant. The mutagenic activity covered nearly a 30-fold range. Compared to white and rosé wines, red wines showed the highest levels of mutagenicity; this wine type included four "very potent" (greater than 3,000 AraR mutants/ml) mutagenic wines. The level of wine mutagenicity did not correlate with either the region or the year of production (vintage). Individual winery methods are suggested as primarily responsible for variations in mutagenic activity. The present study with the Ara test supports the possibility that wine components other than the flavonols quercetin and rutin are the major putative mutagens: (1) white wines, as well as rosé or red wines, were detected as being mutagenic; (2) in no case was activation required for the detection of mutagenicity; (3) mutagen(s) were detected mainly (red wine) when not exclusively (white and rosé wine) in the polar fraction from XAD-2 chromatography. The high sensitivity of the Ara test has allowed the screening of the mutagenicity of a variety of wines with no previous process of extraction or concentration. The comparison of the mutagenic activity of the entire complex mixture to that of its lyophilized residue has revealed a positive synergistic role for ethanol in the mutagenicity of certain wines. Finally, this work suggests that the Ara test is a useful tool for mutagenicity screening in wines. Thus, this test might play an important role in elucidating the genotoxic mechanism of action of alcoholic beverages, and for studying optional production methods to decrease the mutagenicity of commercial wines.     

HPLC-ELSD法测定落叶松多糖中L-阿拉伯糖和D-半乳糖

目的 建立HPLC-ELSD法测定落叶松多糖中L-阿拉伯糖和D-半乳糖。方法 色谱柱为Prevail Carbohydrate ES（250 mm×4.6 mm,5 μm）,流动相为80%乙腈–0.5%乙酸铵水溶液（90∶10）,体积流量1.0 mL/min,柱温室温,进样量20 μL;检测器漂移管温度为100 ℃,载气体积流量为2.5 L/min。结果 L-阿拉伯糖、D-半乳糖分别在2.004 5～20.449 5 μg（R2=0.990 5）、2.041 0～20.410 2 μg（R2=0.995 3）线性关系良好,平均加样回收率分别为99.68%（RSD为1.51%）、99.65%（RSD为1.63%）。结论 本法重现性好,稳定可靠,可作为落叶松多糖的质量控制方法。     

L-阿拉伯糖对肠道微生态的作用及临床应用进展

L-阿拉伯糖是一种天然存在的戊糖,在肠道吸收速率较蔗糖低,能选择性反竞争性抑制小肠黏膜刷状缘的蔗糖酶,抑制人体对蔗糖的代谢和吸收,降低和延缓因蔗糖摄入而导致的血糖升高,具有改善糖耐量和减少脂肪堆积的功效。L-阿拉伯糖促进益生菌增殖改善肠道微生态。肠道微生态由肠道菌群及其生活的环境构成,是影响能量代谢的关键因素,肠道菌群结构和功能的失调将影响糖脂代谢和能量平衡,并引发肠道慢性非特异炎症反应,长期的炎症反应会进一步加剧肠黏膜屏障功能的破坏,形成恶性循环,进而引发代谢综合征。L-阿拉伯糖作为益生元可改善肠道微生态和肠道功能,防治功能性便秘和炎症性肠病。本综述主要介绍L-阿拉伯糖的功能、对肠道微生态的作用及其临床应用,并对L-阿拉伯糖在医学领域的发展前景进行讨论。     

HPLC-ELSD法测定阿拉伯胶酶解液中L-阿拉伯糖含量

目的建立用高效液相色谱-蒸发光散射检测仪(HPLC-ELSD)测定阿拉伯胶酶解液中L-阿拉伯糖含量的方法。方法采用HypersilNH2色谱柱(4.6mm×250nm,5μm),以乙腈-水(80:20)为流动相,流速1mL/min;蒸发光散射检测器检测参数为:漂移管温度100℃,氮气流速为2.5L/min。结果 L-阿拉伯糖与其他糖分的分离效果良好,L-阿拉伯糖的线性回归方程的相关系数为0.9993,线性范围为0.1025～1.025mg/mL,重复性实验RSD为2.03%,回收率为98.68%。结论该法简便,快速,准确,适用于阿拉伯胶酶解液中L-阿拉伯糖含量的测定。     

L-阿拉伯糖对人体血糖水平及体重的影响

目的探讨低热量甜味剂L-阿拉伯糖对人体空腹血糖、餐后血糖水平的影响以及对人体的血糖耐受水平影响等生物功能学作用。方法选取50人(男女各半)随机分为5组,将L-阿拉伯糖与蔗糖以不同配比连续口服30d,记录人体早餐前、早餐后1h、早餐后2h血糖水平变化,观察不同剂量L-阿拉伯糖对人体血糖水平的影响。选取18～23岁之间肥胖人群20名,分为干预组和对照组两组,每天三餐前均服用10g L-阿拉伯糖和作为对照的安慰剂,每15日测量体重,观察体重变化,实验持续180d。结果 3%L-阿拉伯糖即能抑制血糖水平,5%～10%的配比能显著降低餐后血糖(P<0.05),100%与10%配比结果统计学分析无显著差异。食用L-阿拉伯糖组的平均体重持续下降,15d下降0.4～0.5kg。6个月后平均体重降低了5.5kg。结论 L-阿拉伯糖能够明显降低糖耐量,有效调节人体血糖水平,长期服用能够抑制体重增长。     

Tyler’s Honest Herbal: A Sensible Guide to the Use of Herbs and Related Remedies.

Many believe that excessive intake of refined carbohydrates (CHO) plays a major role in the development of obesity/overweight, type 2 diabetes mellitus and insulin resistance, a collection of events commonly referred to as “diabesity,” and have sought natural means to overcome these linked perturbations. As a first approach, planned diets with low portions of refined CHO have become popular. However, these diets do not satisfy everyone; and many are concerned over replacing CHO with more fats. As a second option, addition of soluble fiber to the diet can slow absorption of refined CHO, i.e., lower the glycemic index of foods and overcome or at least ameliorate many of the adverse reactions resulting from increased refined CHO ingestion. Unfortunately, the general public does not favor diets high in fiber content, and various fibers can lead to gastrointestinal problems such as gas and diarrhea. A third choice to favorably influence CHO absorption is to use natural dietary supplements that block or slow CHO absorption in the gastrointestinal tract via inhibiting enzymes necessary for CHO absorption –amylase and alpha-glucosidases. Although a number of natural supplements with anti-amylase activity have been recognized, the most studied and favored one is white kidney bean extract. Animal and human studies clearly show that this agent works in vivo and has clinical utility. This paper reviews many aspects of diabesity and the use of “carb blockers” to prevent and ameliorate the situation. In many respects, carb blockers mimic the beneficial effects of fibers.     

HPLC-ELSD法测定落叶松多糖中L-阿拉伯糖和D-半乳糖

目的建立HPLC-ELSD法测定落叶松多糖中L-阿拉伯糖和D-半乳糖。方法色谱柱为Prevail Carbohydrate ES(250mm×4.6 mm,5μm),流动相为80%乙腈-0.5%乙酸铵水溶液(90∶10),体积流量1.0 mL/min,柱温室温,进样量20μL;检测器漂移管温度为100℃,载气体积流量为2.5 L/min。结果 L-阿拉伯糖、D-半乳糖分别在2.004 5～20.449 5μg(R2=0.9905)、2.041 0～20.410 2μg(R2=0.995 3)线性关系良好,平均加样回收率分别为99.68%(RSD为1.51%)、99.65%(RSD为1.63%)。结论本法重现性好,稳定可靠,可作为落叶松多糖的质量控制方法。