香椿叶多酚的提取分离及其体外对糖尿病关键酶活性的抑制作用

本研究从香椿叶中提取分离多酚,研究多酚对糖尿病关键酶(猪胰腺α-淀粉酶、鼠小肠蔗糖酶和麦芽糖酶)活性的影响。采用活性追踪法,运用多种分离纯化技术和色谱学分析,逐级筛选活性强的部位以及单体化合物。研究发现香椿叶多酚粗提物具有显著的酶抑制作用,猪胰腺α-淀粉酶、鼠小肠蔗糖酶和麦芽糖酶的半数抑制率(IC50)值分别为0.45 mg/mL、1.29 mg/mL和1.41 mg/mL。乙酸乙酯萃取后的70%乙醇洗脱部位为主要活性部位,其对猪胰腺α-淀粉酶、鼠小肠蔗糖酶和麦芽糖酶抑制作用的IC50值分别为0.091mg/mL、0.97 mg/mL和1.00 mg/mL。从活性部位分离出2个单体化合物,分别鉴定为:1,2,3,4,6-O-五没食子酰葡萄糖(PGG)和没食子酸乙酯(EG),其中PGG具有显著的α-淀粉酶抑制活性,IC50值为0.069 mg/mL;EG对蔗糖酶和麦芽糖酶具有一定的抑制活性,IC50值分别0.82 mg/mL和0.81 mg/mL。研究表明多酚化合物是香椿叶的有效降血糖功能成分之一,PGG和EG是主要的活性成分。     

番石榴叶黄酮与多糖提取及其降血糖活性研究

从番石榴叶中提取总黄酮以及多糖,测定其对α-葡萄糖苷酶以及猪胰液α-淀粉酶抑制活性以评估其降血糖活性。结果表明番石榴叶中提取的黄酮类以及多糖类化合物对这2种酶都具有较好的抑制活性,其中黄酮和多糖对蔗糖酶的抑制率分别为63.5%和29.3%,对麦芽糖酶的抑制率分别为47.7%和20.6%,对α-淀粉酶的抑制率分别为54.4%和31.9%。此外,所提取的总黄酮以及多糖对α-葡萄糖苷酶以及猪胰液α-淀粉酶的抑制活性存在协同作用,两者混合的酶抑制活性更好,其中黄酮和多糖的混合物对蔗糖酶,麦芽糖酶以及α-淀粉酶的抑制率分别为75.8%,53.5%和60.1%。     

芹菜素对鼠肠α-葡萄糖苷酶的抑制活性研究

目的:明确芹菜素对鼠肠α-葡萄糖苷酶的抑制活性。方法:建立体外α-葡萄糖苷酶抑制模型,测定芹菜素对α-葡萄糖苷酶、麦芽糖酶和蔗糖酶的抑制活性。进一步利用Lineweaver-Burk作图法,测定芹菜素对麦芽糖酶和蔗糖酶的抑制类型以及抑制常数。采用离体鼠肠进行体外模拟实验,考察芹菜素对麦芽糖酶和蔗糖酶抑制作用的稳定性。实验结果显示,芹菜素对鼠肠α-葡萄糖苷酶具有较好的抑制活性,半抑制浓度为14.475μg/mL。芹菜素对鼠肠麦芽糖酶和蔗糖酶的半抑制浓度分别为165.35μg/mL和149.57μg/mL,抑制类型均为竞争性抑制,抑制常数分别为32.14μg/mL和40μg/mL。在60min内,芹菜素对离体鼠肠体系中蔗糖酶和麦芽糖酶的抑制作用稳定。结论:芹菜素可竞争性抑制鼠肠麦芽糖酶和蔗糖酶的活性,可用于降低糖尿病患者的餐后血糖。     

不同蕨菜制品醇提物体外抗氧化及降血糖活性研究

目的:比较研究不同蕨菜制品醇提取物的体外抗氧化和降血糖活性。方法:分别采用Folin-Ciocalteu法、NaNO₂ -Al（NO₃）₃法测定总酚和总黄酮含量;通过DPPH法、ABTS法、普鲁士蓝法、α-葡萄糖苷酶和α-淀粉酶的抑制活性评价体外抗氧化、降血糖活性;Pearson法分析成分含量与活性的相关性。结果:不同蕨菜醇提物的总酚和总黄酮含量、抗氧化活性、α-葡萄糖苷酶和α-淀粉酶抑制活性差异显著。其中鲜品醇提取物的总酚、总黄酮含量最高,分别可达（593±3.45）mg GA/g、（156.75±1.28）mg RT/g,且鲜品醇提取物铁离子还原能力、ABTS自由基清除能力、DPPH自由基清除能力最强;湿品醇提取物对α-葡萄糖苷酶、α-淀粉酶的抑制作用最强。不同蕨菜醇提取物总酚、总黄酮的含量与其抗氧化活性均呈极显著正相关关系（P<0.01）,与降血糖活性均呈显著正相关关系（P<0.05）。结论:蕨菜鲜品抗氧化活性较强,湿品降血糖活性较强,可能活性成分为多酚类和黄酮类成分。     

芫荽水提物的体外抗氧化活性和抑制α-葡萄糖苷酶作用的研究

研究芫荽籽水提物和成熟芫荽茎叶水提物的体外抗氧化活性和抑制α-葡萄糖苷酶的作用效果。实验测定了提取物中的总黄酮含量,以体外清除羟自由基、DPPH自由基和还原能力的效果来评价两种水提物的抗氧化能力以及对α-葡萄糖苷酶的抑制效果,从而评价其体外降血糖活性,确定了酶的抑制作用类型。结果显示:成熟芫荽茎叶水提物的总黄酮含量要高于芫荽籽水提物,两种水提物的体外抗氧化能力和α-葡萄糖苷酶的抑制效果均呈现出浓度依赖性,且前者总体抗氧化能力和酶抑制效果更优。     

小米多酚体外生物活性的研究

以东方亮1号小米为原料,研究小米多酚的体外抗氧化活性和降血糖活性.对纯化前后的小米多酚进行DPP H自由基清除率、羟基自由基清除率、还原力、对铁离子的络合作用和总抗氧化能力(T-AOC)的评价以及抑制α-葡萄糖苷酶、α-淀粉酶活性的实验,同时测定粗提物与纯化物对葡萄糖的吸收能力.结果表明,抗氧化能力均为阳性对照＞小米多...     

绿茶降糖作用机制的研究

给糖尿病大鼠口服蔗糖或淀粉和绿茶提取物后,观察其对糖尿病大鼠糖耐量及血胰岛素的影响,并用比色法测定对α-葡萄糖苷酶(EC 3.2.1.20)和α-淀粉酶(EC 3.2.1.1)的抑制活性,用快速过滤法观察对兔小肠刷状缘囊泡葡萄糖转运活性的影响.结果表明,绿茶提取物明显改善蔗糖或淀粉负荷糖尿病大鼠的血糖水平.绿茶提取物显示较强的α-葡萄糖苷酶抑制活性,其α-葡萄糖苷酶的半抑制浓度(IC50)值为0.13g/L;对α-淀粉酶的抑制活性则较弱,浓度为1g/L时,其对α-淀粉酶的抑制率为21%.绿茶提取物同时明显降低兔小肠刷状缘囊泡葡萄糖转运能力,其半抑制浓度(IC50)值为3.5g/L.提示,绿茶可延缓小肠对糖的消化吸收,经常食用可能有助于延缓餐后血糖的持续升高. C 3.2.1.1)的抑制活性,用快速过滤法观察对兔小肠刷状缘囊泡葡萄糖转运活性的影响.结果表明,绿茶提取物明显改善蔗糖或淀粉负荷糖尿病大鼠的血糖水平.绿茶提取物显示较强的α-葡萄糖苷酶抑制活性,其α-葡萄糖苷酶的半抑制浓度(IC50)值为0.13g/L;对α-淀粉酶的抑制活性则较弱,浓度为1g/L时,其对α-淀粉酶的抑制率为21%.绿茶提取物同时明显降 兔小肠刷状缘囊泡葡萄糖转运能力,其半抑制浓度(IC50)值为3.5g/L.提示,绿茶可延缓小肠对糖的消化吸收,经常食用可能有助于延缓餐后血糖的持续升     

红茶多糖的体外抗氧化及糖苷酶抑制活性研究

目的研究红茶多糖的体外抗氧化活性和降血糖活性。探讨结构修饰对红茶多糖活性的影响。方法通过还原力实验、羟基自由基清除实验、DPPH清除实验以及脂质过氧化抑制试验模型研究红茶多糖的体外抗氧化活性。通过对α-淀粉酶和α-葡萄糖苷酶的抑制实验研究红茶多糖的降血糖活性,以及对抑制α-葡萄糖苷酶动力学研究红茶多糖的抑制类型。应用超声处理、部分酸解和酶解处理三种不同的处理方式探讨结构修饰与红茶多糖活性的关系。结果在抗氧化实验中,红茶多糖活性具有良好的浓度依赖关系。在α-淀粉酶以及α-葡萄糖苷酶的抑制试验中,红茶多糖显示出一定的抑制作用。由动力学研究推测红茶多糖对a-葡萄糖苷酶的抑制作用属于非竞争性抑制。三种结构修饰方式对活性均有影响,但变化趋势与处理方式和活性模型有关。结论红茶多糖是一种良好的抗氧化剂,并具有一定的降血糖活性,相应的结构修饰可提高红茶多糖的活性。     

桑葚、百香果、柚子及火龙果复合果汁协同抑制α-葡萄糖苷酶的作用及机制

为探究果汁在复配体系中对于生物活性的协同增效作用,选择具有丰富天然活性物质的桑葚、百香果、柚子、火龙果为原材料,以多酚含量等比例混合制备得到复合果汁,评价其抗氧化及降血糖活性.结果表明,通过果汁复配,果汁样品的氧化自由基吸收能力无明显改善,而降血糖活性研究结果显示,复合果汁抑制α-葡萄糖苷酶的IC50值在0.16～0....     

水果酵素体外抗氧化及抑制α-淀粉酶和α-葡萄糖苷酶活性的研究

为明确水果酵素在自然发酵过程中体外抗氧化活性和对α-淀粉酶、α-葡萄糖苷酶的抑制作用,以DPPH自由基清除能力和ABTS自由基清除能力为指标,研究酵素的抗氧化活性;以可溶性淀粉和4-硝基苯基-α-D-吡喃葡萄糖苷(PNPG)为底物测定酵素对α-淀粉酶和α-葡萄糖苷酶的抑制作用。试验结果表明,酵素在发酵结束后DPPH自由基清除率和ABTS自由基清除率分别达到87.19%和100.00%;对α-淀粉酶和α-葡萄糖苷酶的抑制率分别达到99.57%和81.67%。酵素对DPPH自由基、ABTS自由基的清除作用和对α-淀粉酶、α-葡萄糖苷酶的抑制作用明显,表明具有较好的抗氧化活性和降血糖潜力。     

Chemical composition and bioactivities of the polyphenolic-rich extract of Ormenis africana Jord. and Fourr

Ormenis africana is an endemic North African species used in folk medicine because of its hypoglycemic property. In this study, the α-amylase and α-glucosidase inhibition and antioxidant activities of the polyphenolic-rich extract from O. africana were determined. The chemical composition was made using liquid chromatography with photodiode array and electrospray ionization mass spectrometry method and the identification of phenolics was assessed by comparing their retention times and ultraviolet and mass spectra with those of the standards and/or reported in the literature. The total phenolic content was estimated by the Folin–Ciocalteu method. The antidiabetic potential was estimated by the determination of α-amylase and α-glucosidase inhibition in vitro. Four assays were used for the evaluation of antioxidant activity of the extracts. Seventeen phenolic compounds were detected. The major peaks are chlorogenic acid, 5-O-di-caffeoylquinic acid, and apigenin and luteolin derivatives. The polyphenolic-rich extract showed remarkable α-amylase and α-glucosidase inhibition activity in a concentration dependent manner. Furthermore, the extract also demonstrated high antioxidant activities. O. africana can serve as a potential natural source for the development of a novel α-amylase and α-glucosidase inhibitory agents against diabetic complications.     

银耳多糖对淀粉消化酶的抑制作用及其机理研究

目的:研究银耳多糖对胰α-淀粉酶和α-葡萄糖苷酶的抑制作用及机制。方法:以干银耳为原料,分别采用碱法提取、酶法脱蛋白和柱层析分离,得到总糖含量为92.45%的银耳多糖（Tremella fuciformis polysaccharide,TP）,采用可见光分光光度法分析了TP对胰α-淀粉酶和α-葡萄糖苷酶的抑制作用,采用荧光光谱法和圆二色谱法表征了TP对该两种酶结构的影响。结果:TP能抑制该两种酶的活性,其对胰α-淀粉酶的抑制作用明显高于α-葡萄糖苷酶,对该两种酶的半抑制浓度（IC₅₀）分别为7.6835和16.9306 mg/mL。TP通过与该两种淀粉消化酶发生相互作用抑制其活性。TP与胰α-淀粉酶相互作用明显,可静态猝灭此酶,改变其二级结构;TP与α-葡萄糖苷酶相互作用微弱,不能改变其二级结构。结论:TP通过与淀粉消化酶发生相互作用抑制其活性。     

Seasonal influence on phenolic-mediated antihyperglycemic properties of Canadian sugar and red maple leaves using in vitro assay models

Red and sugar maple leaves collected in the summer and fall from Canada, were evaluated for phenolic content, antioxidant, α-glucosidase, and α-amylase inhibitory activities variation. The phenolic contents of summer red maple leaves (RML-S) and summer sugar maple leaves (SML-S) were higher than red and sugar maple leaves collected in fall (RML-F and SML-F, respectively). HPLC analyses showed differences in phenolic compounds present in the SML samples compared to the RML samples. The extracts were assayed for yeast and rat α-glucosidase inhibitory activities. Both results showed that SML-S extracts had the highest inhibitory activity which could possibly be attributed to the unique phenolics present therein. Milder effects were observed in terms of α-amylase inhibitory activity, with RML-F having the highest inhibitory activity. These results suggest that maple tree leaf extracts may have potential for phenolic-mediated α-glucosidase inhibition, relevant to type 2 diabetes management, with SML-S extract having the highest bioactivity.     

番石榴不同部位乙醇提取物的抗氧化、降血糖及酪氨酸酶抑制活性

目的:比较研究番石榴不同部位(根、茎、叶、果实)乙醇提取物抗氧化、降血糖和抑制酪氨酸酶活性.方法:分别采用ABTS法和DPPH法、pNPG法和DNS法、L-DOPA法评价番石榴不同部位抗氧化活性、降血糖活性和酪氨酸酶抑制活性.结果:番石榴不同部位乙醇提取物均具有一定的体外抗氧化、降血糖和酪氨酸酶抑制活性,并呈现一定的量...     

Inhibitory potential of herb,fruit, and fungal-enriched cheese against key enzymes linked to type 2 diabetes and hypertension

In the current study, three different types of cheese, cheddar, feta, and Roquefort, were screened to determine the variations in phenolic-linked antioxidant activity and the potential to inhibit key enzymes relevant to type 2 diabetes and related hypertension. The cheese samples were assayed for total phenolic content, related antioxidant activity, and inhibition of α-glucosidase, pancreatic α-amylase inhibitory activity, and the angiotensin-converting enzyme (ACE)-I inhibitory activity. The three fungal-enriched Roquefort cheese samples had the highest total phenolic content. The phenolic content in the herb cheese was slightly but not significantly higher compared to plain cheese. Roquefort cheese samples had the highest antioxidant-linked DPPH (free radical) scavenging activity and as expected DPPH radical scavenging activity was higher in the herb cheese compared to plain cheese. All samples had some α-glucosidase and α-amylase inhibitory activities, with cranberry-enriched cheese having the highest activities. However, no correlation to soluble phenolic content was observed. All the cheese samples had very high anti-ACE-I inhibitory activity, indicating no correlation to phenolic content and activity was even high in 10× diluted samples. The highest ACE-I inhibitory activity was observed in plain and herb-enriched cheddar cheese as well as cranberry-enriched cheese. These studies indicate that cranberry-enriched cheese had the best potential for inhibition of α-glucosidase and α-amylase relevant for type 2 diabetes management, whereas any cheese product had potential for ACE-I inhibition linked to hypertension management, indicating likely the role of other factors such as peptides from cheese fermentation.Industrial relevanceThis research is focused on screening of different types of commercial plain, herbal, fruit, and fungal-enriched to provide a strong biochemical rationale for further design of functional cheese products for anti-type 2 diabetic and relevant hypertension management. A better understanding of these functional attributes provides a strong biochemical rationale for design in vivo and clinical studies from which right design of functional food can be established.     

提取方法对覆盆子多糖理化性质和体外生物活性的影响

本论文对覆盆子采取热水提法、碱提法、酸提法和酶提法提取覆盆子多糖(raspberry polysaccharides,RAPs),研究其对多糖的物化性质和体外生物活性的影响.利用扫描电镜和傅里叶红外光谱对多糖的微观结构和官能团进行表征,通过HR-1 Discovery混合流变仪对其流变性质进行测定,以DPPH、ABTS...     

Enhanced antioxidant and antidiabetic activities of barley and wheat after soaking with tea catechin

Barley and wheat were investigated as natural α-glucosidase inhibitors having potent inhibitory activities against the antidiabetic enzymes α-glucosidase, maltase, and sucrase. After soaking with tea catechin as an elicitor, extracts of barley and wheat were prepared using thermal treatment in an autoclave at 121°C for 15 min, then the in vitro antioxidant and antidiabetic activities were determined. The total soluble phenolics contents of barley and wheat during soaking were increased by addition of tea catechin, which also contributed to the peroxyl radical-scavenging activity and the reducing capacity. The rat α-glucosidase, maltase, and sucrase inhibitory activities of barley were increased with an increase in the added tea catechin concentration from 0.1% to 0.5%. Tea catechin may have a role as an elicitor for production of phenolics that exhibit antioxidant activities and rat-intestinal maltase and sucrase inhibitory activities during the soaking process of barley and wheat.     

三种食用菌提取物体外抗氧化与降血糖活性研究

目的:为评价三种食用菌体外抗氧化与降血糖作用。方法:采用水杨酸显色法、DPPH·显色法、铁氰化钾显色法测定三种食用菌及副产物(竹荪、竹荪菌托、茶树菇、松乳菇)提取物的抗氧化能力,再通过α-淀粉酶和α-葡萄糖苷酶活性抑制作用分析提取物的降血糖活性。结果:在实验浓度(0.5~5 mg/mL)范围内三种食用菌及副产物的提取物具有一定的抗氧化和降血糖作用,且存在明显的量效关系。抗氧化以V_C作为阳性对照,降血糖组间进行对照。当浓度达到5 mg/mL时,茶树菇提取物对·OH和DPPH·的清除率最高可达89.45%和87.81%,对Fe3+的还原能力与V_C相近,IC₅₀均为1.04 mg/mL;而竹荪和竹荪菌托提取物对·OH(45.19%和36.04%)、DPPH·(44.30%和36.81%)的清除率和对Fe3+的还原能力(46.61%和48.09%)均较弱,且IC₅₀值均超出实验浓度。当浓度达到5 mg/mL时,茶树菇提取物对α-淀粉酶和α-葡萄糖苷酶活性的抑制率分别62.15%和57.08%,IC₅₀值为3.82和4.10 mg/mL;松乳菇提取物对两种酶的抑制率分别为83.52%和75.43%,IC₅₀值为2.22和2.53 mg/mL;而竹荪和竹荪菌托提取物对α-淀粉酶(15.15%和24.56%)和α-葡萄糖苷酶(26.20%和23.41%)活性的抑制率均较低,且IC₅₀值均超出实验浓度。结论:茶树菇提取物降血糖和抗氧化作用均较强,而松乳菇提取物的降血糖作用较强而抗氧化作用较弱,竹荪和竹荪菌托提取物的抗氧化活性和降血糖活性均较弱。     

罗望子壳降血糖活性化学成分的研究

本文测定了罗望子壳醇提取物各个活性部位的降血糖活性,发现其正丁醇相活性最高.接着对正丁醇相的化学成分进行分离鉴定,采用大孔吸附树脂(HP-20),正相硅胶柱层析,反相硅胶柱层析(RP-18),以及葡聚糖凝胶(LH-20)等分离手段分离鉴定其主要化学成分.通过<'1>H NMR,<'13>C NMR技术并结合文献对照对7...