藤茶抗氧化活性研究

本文建立体外二苯代苦味酰基自由基(DPPH·)体系,并采用连苯三酚法在碱性溶液中自氧化反应产生超氧阴离子自由基(O2-+)和邻二氮菲-Fe2+/H2 O2体系产生羟自由基(·OH)法,在酶标仪上检测藤茶总黄酮、二氢杨梅素和杨梅素对DPPH·、O2-+和·OH的清除作用.结果表明:藤茶各提取物均有不同程度的体外抗氧化效果,杨梅素对DPPH·的清除作用最强DPPH·IC50 (2.91±0.28) mg/L,二氢杨梅素对O2-+的清除作用最强IC50 (3.88±0.99) mg/L,对·OH的清除效果是杨梅素＞二氢杨梅素＞藤茶总黄酮.确定杨梅素和二氢杨梅素为藤茶的主要抗氧化相关活性成分.     

二氢杨梅素结构修饰及生物活性研究进展

二氢杨梅素是一种二氢黄酮醇,具有抗菌、抗炎、抗肿瘤以及保肝护肝等多种生物活性。由于其结构中的6个羟基导致其脂溶性差及生物利用度低,因此对其进行结构修饰以期提高生物利用度和生物活性。本文综述了二氢杨梅素的化学法结构修饰及其生物活性等研究工作,化学修饰方法涉及醚化反应、酯化反应和金属配合物等方法,合成的衍生物具有抗病毒、抗菌、抗氧化、神经保护以及抑制肿瘤细胞增殖等活性,并且提出二氢杨梅素结构修饰过程中存在的挑战及发展方向,为更好地开发二氢杨梅素衍生物提供技术服务。     

霉茶黄酮对大鼠离体胸主动脉环的影响

用离体大鼠胸主动脉血管环为研究对象,经生物信号采集系统采集并分析血管环张力变化,观察霉茶总黄酮、二氢杨梅素、杨梅素对静息血管的影响以及它们对去甲肾上腺素(NA)所致的缩血管反应的影响。研究发现霉茶总黄酮、二氢杨梅素、杨梅素均可浓度依赖性增加血管环静息张力;霉茶总黄酮能使NA缩血管的量-效曲线非平行右移并降低其效能(Emax);二氢杨梅素、二氢杨梅素与杨梅素的混合物有与霉茶总黄酮相似的效应;二氢杨梅素与杨梅素合用使NA收缩血管的Emax降低,明显强于二者单独使用;当二氢杨梅素与杨梅素浓度比为10∶1时,拮抗NA缩血管的效应最佳。结果显示霉茶总黄酮对静息血管有剂量依赖性收缩作用但能明显拮抗NA缩血管效应,二氢杨梅素与杨梅素对NA诱导血管收缩反应有协同增效作用且最佳协同比例为10∶1。     

二氢杨梅素对抗生素应激小鼠血清抗氧化性和肠道微生物多样性的影响

【背景】二氢杨梅素(dihydromyricetin, DMY)是一类存在于藤茶中的主要黄酮类化合物,具有抗氧化、抗炎等功能,其药用价值受到广泛关注,但其在生物体内的生物活性及肠道中的分解代谢机制尚不清楚。【目的】探究二氢杨梅素对抗生素应激下小鼠的血清抗氧化性和肠道微生物多样性的影响。【方法】将小鼠分为对照组、抗生素组、抗生素+二氢杨梅素组,检测各组小鼠血清中的抗氧化指标,利用高通量测序分析组间肠道微生物多样性的差异,通过实时荧光定量PCR(real-time fluorescence quantitative polymerase chain reaction, RT-qPCR)验证特定菌群组间的相对丰度差异。【结果】二氢杨梅素显著提高了抗生素应激小鼠血清中过氧化氢酶(catalase, CAT)、超氧化物歧化酶(superoxide dismutase, SOD)、谷胱甘肽过氧化物酶(glutataione peroxidase, GSH-PX)活性(P<0.05),显著降低丙二醛(malondialdehyde,MDA)含量(P<0.05),催化一氧化氮(nitric...     

高速逆流色谱纯化二氢杨梅素

本实验采用高速逆流色谱纯化二氢杨梅素。结果表明：选用溶剂系统为石油醚：乙酸乙酯：甲醇：水(1：3：2：2),在转速为800r／min,进样量为200mg、进样速度为1．5ml／min的条件下,能很好地将80％左右的粗二氢杨梅素提纯到90％以上,进样速度、进样量对二氢杨梅素的分离有一定影响。     

植物黄酮二氢杨梅素的提纯及结晶形态研究

显齿葡萄属植物富含黄酮物质。研究对显齿葡萄黄酮提取物二氢杨梅素的提纯及结晶态进行了初步探讨。结果表明:以水作为结晶溶剂进行多次重结晶,可有效去除植物黄酮提取物的杂质,总黄酮含量由原来的86%提高至96.5%。二氢杨梅素在水相中的结晶态多为针状结晶,水相保温结晶呈放射性棒状结晶。在pH4.5的条件下,其溶解度最低可获得较高的回收率。     

从藤茶中提取二氢杨梅素的微波萃取工艺研究

用正交设计法,以水为溶剂,考察了提取温度、微波辐射时间及料液比3个因素,每个因素3个水平,选择L9（33）正交设计表,用HPLC法测定二氢杨梅素,并以其含量作为评价指标.结果表明,在提取温度为95℃ ,微波辐射时间为15min,料液比为1：20时二氢杨梅素的提取率最高.     

“增温溶解,保温过柱,温水解吸“提制二氢杨梅素(二)

本文对“增温溶解 ,保温过柱 ,温水解吸”方法提制显齿蛇葡萄中二氢杨梅素的提制条件以及高纯度的二氢杨梅素制备进行了研究。结果表明 :过柱时上柱料液浓度、过柱速度以及解吸时水的流速对二氢杨梅素的提制均有影响。适宜选择条件分别为 5mg/ml的上柱料液浓度、2BV/h的过柱速度、6～10BV/h的水解吸速度。利用重结晶可以制备高纯度的二氢杨梅素     

响应面优化超声辅助法提取拐枣种子中二氢杨梅素的工艺

二氢杨梅素和杨梅素是拐枣种子中的重要成分。通过超声辅助法从拐枣种子中提取二氢杨梅素，采用单因素法考察乙醇体积分数、超声辐照功率、提取温度、液料比和超声辐照时间影响参数的基础上，并选用Box-Behnken响应面设计法分析建立了超声辐照功率、超声辐照时间和液料比的二次多项式模型，优化提取工艺。结果得到超声辅助法提取拐枣种子中二氢杨梅素的最佳工艺参数为：乙醇体积分数为60%、超声辐照功率140 W、超声辐照时间30 min、液料比20.5 mL·g^-1，提取温度40℃。在此最佳条件下，二氢杨梅素得率为2.14±0.09 mg·g^-1。本提取方法简单快速，效率高，有利于拐枣资源的综合加工利用。     

“增温溶解,保温过柱,温水解吸“提制二氢杨梅素(一)

采用“增温溶解 ,保温过柱 ,温水解吸”的方法对显齿蛇葡萄中的二氢杨梅素进行提制研究。结果表明 :该方法的适宜温度为 5 0～ 70℃ ,最好为 6 0℃ ,方法能很好地将 70 %左右的二氢杨梅素提纯到80 % ;提纯二氢杨梅素时 ,单位数量的D 16大孔吸附树脂处理料液的数量 ,主要取决于料液中二氢杨梅素的纯度。     

Dihydromyricetin resists inflammation-induced muscle atrophy via ryanodine receptor-CaMKK-AMPK signal pathway

Skeletal muscle plays a pivotal role in the maintenance of physical and metabolic health. Skeletal muscle atrophy usually results in physical disability, inferior quality of life and higher health care costs. The higher incidence of muscle atrophy in obese and ageing groups is due to increased levels of inflammatory factors during obesity and ageing. Dihydromyricetin, as a bioactive polyphenol, has been used for anti-inflammatory, anti-tumour and improving insulin sensitivity. However, there are no published reports demonstrated the dihydromyricetin effect on inflammation-induced skeletal muscle atrophy. In this study, we first confirmed the role of dihydromyricetin in inflammation-induced skeletal muscle atrophy in vivo and in vitro. Then, we demonstrated that dihydromyricetin resisted inflammation-induced skeletal muscle atrophy by activating Ca²⁺-CaMKK-AMPK through signal pathway blockers, Ca²⁺ probes and immunofluorescence. Finally, we clarified that dihydromyricetin activated Ca²⁺-CaMKK-AMPK signalling pathway through interaction with the ryanodine receptor, its target protein, by drug affinity responsive target stability (DARTS). Our results not only demonstrated that dihydromyricetin resisted inflammation-induced muscle atrophy via the ryanodine receptor-CaMKK-AMPK signal pathway but also discovered that the target protein of dihydromyricetin is the ryanodine receptor. Our results provided experimental data for the development of dihydromyricetin as a functional food and new therapeutic strategies for treating or preventing skeletal muscle atrophy.     

Investigation on the interaction between myricetin and dihydromyricetin with trypsin, α-chymotrypsin,lysozyme by spectroscopy and molecular docking methods

The interaction between myricetin and dihydromyricetin with trypsin, α-chymotrypsin and lysozyme was investigated using multispectral and molecular docking methods. The results of fluorescence quenching revealed that myricetin and dihydromyricetin could quench the intrinsic fluorescence of three different proteinases through a static quenching procedure. The binding constant and number of binding sites at different temperatures were measured. The thermodynamic parameters obtained at different temperatures showed van der Waals interactions and hydrogen bonds played the main roles in the interaction of myricetin with trypsin and lysozyme, hydrophobic force was dominant both in myricetin with α-chymotrypsin interaction and dihydromyricetin with trypsin and lysozyme interaction, as for the electrostatic forces, it was mainly the driving force in dihydromyricetin binding to α-chymotrypsin. There was non-radiative energy transfer between three proteinases and myricetin or dihydromyricetin with high probability. The microenvironment of trypsin, α-chymotrypsin and lysozyme is changed. The docking studies revealed that myricetin and dihydromyricetin entered the hydrophobic cavity of three proteinases and formed hydrogen bonds. The binding affinity of myricetin or dihydromyricetin is different with the trypsin, α-chymotrypsin and lysozyme due to the different molecular structure.     

二氢杨梅素对几种食品常见菌的抑制效果

以酵母菌（saccharomyces cerevlsiae),桔青霉菌（penicillium citrinum）,牛奶酸败混合菌群为试验材料,研究了类黄酮物质二氢杨梅树皮素（DMY）对酵母菌,霉菌,细菌三种类型的微生物的抑制效果,结果表明：DMY对牛奶酸败菌和青霉菌具有明显的抑制作用,且抑菌效果优于常见的防腐剂苯甲酸,而对酵母菌的抑制效果不显著,因此,DMY可作为食品添加剂应用于乳制品及易染霉菌的食品的保藏。     

显齿蛇葡萄基本成分研究

对显齿蛇葡萄（Ampelopsis grossdentata)幼嫩茎叶中的粗蛋白,水溶性蛋白,氨基酸组分,总灰分,无机营养元素,多酚,水提取物,总黄酮以及其中的二氢杨梅素含量作了测定,结果表明：显齿蛇葡萄幼嫩茎叶中粗蛋白氨基酸及无机营养元素含量丰富,多酚,水提取率,总黄酮和二氢杨梅素含量高。显齿蛇葡萄幼嫩茎叶既可粗加工为具特殊风味的类茶产品,又可作集营养,保健,药用功能于一体的资源加以深度开发。     

Dihydromyricetin is a new inhibitor of influenza polymerase PB2 subunit and influenza-induced inflammation

Development of new and effective anti-influenza drugs is critical for the treatment of influenza virus infection. The polymerase basic 2 (PB2) subunit as a core subunit of influenza A virus RNA polymerase complex is considered to be an attractive drug target for anti-influenza drug discovery. Dihydromyricetin, as a natural flavonoid, has a wide range of biological activities, but its anti-influenza A virus activity is ambiguous. Here, we found dihydromyricetin could inhibit the replication of a variety of influenza A virus strains. Mechanism studies demonstrated that dihydromyricetin reduced viral polymerase activity via selective inhibition of viral PB2 subunit, and decreased relative amounts of viral mRNA and genomic RNA during influenza A virus infection. The binding affinity and molecular docking analyses revealed that dihydromyricetin interacted with the PB2 cap-binding pocket, functioned as a cap-binding competitor. Interestingly, dihydromyricetin also reduced cellular immune injury by inhibiting TLR3 signaling pathway. Additionally, combination treatment of dihydromyricetin with zanamivir exerted a synergistic anti-influenza effect. Altogether, our experiments reveal the antiviral and anti-inflammatory activities of dihydromyricetin in vitro against influenza virus infection, which provides a new insight into the development of novel anti-influenza drugs.