光果甘草乙酸乙酯相对酪氨酸酶的抑制作用

酪氨酸酶是生物体合成黑色素的关键酶,实验以光果甘草为原料,研究其提取物乙酸乙酯相对酪氨酸酶活性的抑制作用及机理.采用L-多巴速率氧化法体外测定光果甘草提取物乙酸乙酯相对酪氨酸酶的抑制活性,并绘制了Lineweaver-Burk双倒数曲线以此判断其抑制类型.结果表明光果甘草提取物乙酸乙酯相半抑制浓度(IC50)为(266.5±1.4)mg/L.对酪氨酸酶抑制机理测定分析的结果表明,光果甘草提取物乙酸乙酯相对酪氨酸酶活性的抑制作用表现为可逆抑制,对酪氨酸酶活性的抑制类型是混合型抑制,抑制常数KI为(182.86±1.43)mg/L,α值为(15.49±0.68)mg/L.可见甘草提取物乙酸乙酯相对酪氨酸酶有较强抑制作用.     

胀果甘草提取物对蘑菇酪氨酸酶的抑制作用

筛选胀果甘草是对蘑菇酪氨酸酶抑制活性最强的提取物,并研究其对蘑菇酪氨酸酶的抑制类型,探究其抑制作用机理。 考察了胀果甘草7种不同溶剂包括甘草酸、提酸废液、石油醚、氯仿、乙酸乙酯、正丁醇及水提取物对蘑菇酪氨酸酶的抑制作用和对2,2-联氮-双(3-乙基苯并噻唑啉-6-磺酸)二胺盐(ABTS)自由基阳离子(ABTS·﹢)、羟基自由基(HO·)的清除作用,根据双倒数曲线图形判断对蘑菇酪氨酸酶的抑制作用类型,结合抗氧化能力探究对蘑菇酪氨酸酶的抑制作用机理。 在胀果甘草7种溶剂提取物中,以乙酸乙酯提取物对蘑菇酪氨酸酶具有最强的抑制作用,IC50为3.4775 g/L,双倒数曲线做图得到了一组纵轴截距不变的曲线,抑制常数K1为0.6667 g/L,胀果甘草乙酸乙酯提取物也具有最强的清除ABTS·﹢、HO·的能力,半清除浓度和速率常数分别为0.0442 g/L和4.634×108 L/(g·s)。 胀果甘草乙酸乙酯提取物对蘑菇酪氨酸酶的抑制作用是可逆竞争性抑制,推测其对酪氨酸酶的抑制是通过清除了氧自由基和作为竞争性底物而实现的。     

油茶果壳多酚对酪氨酸酶活性的影响

研究了油茶果壳的提取物油茶多酚对酪氨酸酶活性的影响,考察了不同底物浓度下,油茶多酚对酪氨酸酶活性的影响。结果表明,反应时间、底物浓度对酪氨酸酶的活性有不同程度的影响,油茶多酚对酪氨酸酶具有激活作用,在25 min时,油茶多酚对酪氨酸激活作用的最佳条件为底物浓度为7.5×10~(-5) mmol/L、油茶多酚浓度为2 000μg/mL。     

丹皮酚在石墨烯修饰电极上的电化学行为及应用研究

利用电化学还原法制备了还原氧化石墨烯修饰电极(rGO/GCE)。采用循环伏安法研究了丹皮酚在rGO/GCE上的电化学行为。结果表明,rGO/GCE对丹皮酚有较好的电催化活性。考察了缓冲溶液pH值、扫描圈数、富集时间、扫速等对丹皮酚电化学响应的影响,建立了检测丹皮酚的标准曲线。丹皮酚峰电流与丹皮酚浓度在4.0×10~(-6)～8.0×10~(-5) mol·L~(-1)范围内有良好线性关系:I_(pa)=0.49 c(μmol·L~(-1))+8.46(R~(2 )=0.9786),检出限为1.0×10~(-6) mol·L~(-1)。将此方法应用于丹皮酚软膏样品中丹皮酚含量的测定,回收率为90.0%～108.6%。     

二氢杨梅素对酪氨酸酶抑制作用研究

研究了二氢杨梅素对酪氨酸酶的单酚酶和二酚酶抑制作用和机理。结果表明,二氢杨梅素对单酚酶、二酚酶的抑制率分别为95.87%、69.01%;二氢杨梅素对单酚酶的抑制作用表现为酶催化反应的迟滞时间延长;二氢杨梅素对二酚酶的抑制作用表现为可逆混合型抑制,对游离酶的抑制常数(KI)和对酶-底物络合物的抑制常数(KIS)分别为150μmol.L-1和83μmol.L-1。二氢杨梅素可作为天然的酪氨酸酶抑制剂。     

反相高效液相色谱法测定伤湿气雾剂中丹皮酚含量

建立了反相高效液相色谱法测定伤湿气雾剂中丹皮酚含量的方法。在Polaris C18色谱柱(150 mm×4.6 mm i.d.,5μm)上,检测波长274 nm,柱温30℃条件下,研究了流动相中甲醇的含量对样品分离的影响。结果表明,V甲醇∶V水=45∶55时,效果最佳。丹皮酚的质量在0.021-0.420μg之间与峰面积呈线性关系。并测定了不同批号伤湿气雾剂中丹皮酚的含量,测定结果的RSD值(n=5)在0.91%-1.31%之间。对回收率作了试验,其结果在94.6%-98.2%之间。     

超高效液相色谱法同时测定牙膏中5种植物源活性成分

建立了同时测定牙膏中丹皮酚(Pae)、麝香草酚(Thy)、和厚朴酚(Hon)、厚朴酚(Mag)、甘草次酸(Gly)5种植物源活性成分的超高效液相色谱方法。牙膏样品以90%甲醇为溶剂超声提取,离心取上清液过滤后进行分析,采用Waters ACQUITY UPLCHSS C_(18)(2. 1 mm×100 mm,1. 8μm)为分离柱,乙腈-0. 1%甲酸(pH 2. 8)为流动相,梯度洗脱,流速为0. 3 mL/min,二极管阵列检测器(PDA)的检测波长为275、250nm,外标法定量。结果表明,5种植物源活性成分在2～100 mg/L质量浓度范围内呈良好的线性关系,相关系数(r)均大于0. 999;检出限为0. 2～1. 0 mg/kg,定量下限为0. 8～3. 5 mg/kg;在4个加标水平下的平均回收率为90. 5%～99. 4%,相对标准偏差(RSD)为0. 7%～5. 1%。该法分析快速、重复性好、准确性好、灵敏度高,已应用于实际牙膏样品的测定。     

聚酰胺-大孔树脂纯化海棠花中总黄酮及其抗肿瘤活性研究

采用聚酰胺-大孔树脂联用技术纯化海棠花总黄酮成分,检测总黄酮对小鼠S-180肉瘤的抑制作用。选择提取液-聚酰胺(g/g,1∶1)拌匀,低温烘干,加入NKA-9大孔树脂柱,树脂-提取液(g/g,10∶2)上柱(柱径高比1∶10),以水洗脱至无色,再以60%乙醇洗脱,洗脱液收集量为10BV,总黄酮纯度达85.96%。海棠花总黄酮体外抗肿瘤活性显示,当剂量为50mg·kg-1时,抑瘤率达44.28%,并可显著提高小鼠的胸腺指数和脾脏指数。     

丹皮酚腙类化合物的合成及其抗菌活性

根据拼接原理将活性基团腙引入中药活性成分丹皮酚中对其结构进行修饰,以丹皮酚为原料,与80%水合肼在乙醇中反应得到中间体丹皮酚腙(2),然后与芳香醛反应合成了10个芳甲叉基丹皮酚腙(3a-3j),其结构经IR、~1H NMR、~(13)C NMR和ESI-MS表征。采用二倍稀释法测定目标化合物对金黄色葡萄球菌和大肠杆菌的最低抑菌浓度(MIC),结果表明:大部分化合物金黄色葡萄球菌和大肠杆菌表现出较好的抑菌活性,特别是化合物3i对金黄色葡萄球菌的的MIC为2μg·mL~(-1),优于阳性对照药环丙沙星。     

百合磷茎中Regaloside A、Acetylregaloside C与Regaloside B高速逆流色谱分离及生物活性研究

建立了高速逆流色谱分离制备药食同源植物百合磷茎中3个酚酸甘油酯苷的方法,同时测定了化合物对1,1-二苯基-2-三硝基苯肼(DPPH)自由基的清除作用、脂质的过氧化抑制作用及对α-淀粉酶活性的促进作用。以乙酸乙酯-正丁醇-水(0. 5%乙酸,3∶1. 5∶5,体积比)为溶剂系统,上相为固定相,下相为流动相,从250 mg百合磷茎提取物中分离得到4. 2 mg纯度为96. 2%的化合物1,2. 3 mg纯度为95. 1%的化合物2,5. 8 mg纯度为98. 8%的化合物3。经质谱及核磁共振鉴定化合物1~3分别为王百合苷A(Regaloside A)、乙酰化王百合苷C(Acetylregaloside C)、王百合苷B(Regaloside B);活性研究表明,Acetylregaloside C对DPPH自由基清除作用及脂质过氧化抑制作用均最强,Regaloside A与Regaloside B对DPPH自由基清除作用很弱,对脂质过氧化有一定的抑制作用且相近,化合物抗氧化作用强弱为:化合物2 1≈3。化合物在不同浓度下对α-淀粉酶活性的促进作用具有一定差异,但化合物间无显著差异。     

十二烷基苯磺酸钠-超临界二氧化碳萃取槐花总黄酮的工艺研究

在单因素试验的基础上,以槐花总黄酮提取率为评价指标,进行了L9(34)正交优化实验,考察了表面活性剂十二烷基苯磺酸钠(SDBS)对超临界CO2萃取槐花总黄酮提取率的影响,确定了槐花总黄酮的优化提取工艺.结果表明,引入十二烷基苯磺酸钠使得槐花总黄酮的提取率提高了93.7%.槐花总黄酮的优化提取工艺为:萃取温度50℃,萃取压力35MPa,SDBS质量分数为2%,夹带剂乙醇体积分数75%.     

微波辅助萃取-液相色谱-串联质谱法测定植物源产品中的阿维菌素B1a残留量

建立了植物源产品茶叶、粮谷、中药材中阿维菌素B1a残留量的液相色谱-串联质谱（LC-MS／MS）测定方法。样品用丙酮-二氯甲烷（体积比1：1）微波辅助提取,提取液经石墨化炭黑／氨基（Carb／NH2）固相萃取小柱净化。采用Hypersil Gold C18色谱柱（150mm×2．1mm,5μm）,乙腈-2．5mmol／L乙酸铵水溶液为流动相,以电喷雾电离正离子（ESI＋）、多反应监测模式（MRM）定性、定量测定阿维菌素B1a,采用基质标准曲线外标法定量。在5—100μg／L范围内,阿维菌素B1a的峰面积与质量浓度呈线性关系,相关系数大于0．998,方法的检出限（S／N〉3）为5μg／k,定量限（S／N〉10）为10μg／kg。取有代表性的绿茶、小麦、丹参阴性样品进行加标回收试验,在10,50μg／kg加标水平下,回收率为75％-87％,相对标准偏差为4．04％-6．38％（n=5）。该法提取效果好、净化较彻底,灵敏度满足国内外限量标准的要求,适合复杂基质植物源产品中阿维菌素B1a残留量的测定。     

Effect of extraction conditions on measured total polyphenol contents and antioxidant and antibacterial activities of black tea

Black tea was extracted for 2, 8 and 18 h with absolute acetone, N,N-dimethyl-formamide (DMF), ethanol and methanol and their 50% aqueous solutions. The extracts were screened for total polyphenol contents, antioxidant and antibacterial activities. The polyphenol content of the extracts was found to be in the range of 0.44-114.01 mg gallic acid equivalents (GAE)/g dry weight tea, depending on the solvent used and the length of the extraction process. In general, aqueous acetone or DMF extracts displayed the highest polyphenol contents and antioxidant activity, while absolute acetone was the least efficient solvent. Antioxidant activities of tea extracts tested using the reducing power and 2,2-diphenyl-1-picryhydrazyl (DPPH) radical methods ranged from 0.09 to 1.18 and from 2.60 to 95.42 %, respectively, depending on the extraction conditions and the antioxidant activities correlated well with the polyphenol concentrations. Aqueous solvent black tea extracts also possessed antibacterial activity, depending on the solvent used and bacterial species tested. Staphylococcus aureus was found to be the most sensitive to all tea extracts, except for the methanol extract. Tea extracts were not effective against Y. enterocolitica, L. monocytogenes and E. coli O157:H7.     

超声波提取含羞草种子中总黄酮工艺条件优化研究

采用超声提取法对含羞草种子中黄酮类物质进行提取,对提取工艺条件如溶剂、配料比、浸泡时间、提取温度、提取时间进行了优化。在单试验的基础上进行正交试验,得出黄酮类物质的最佳提取工艺条件:乙醇体积分数为60%,含羞草种子与60%乙醇配料比(g∶m L)为1∶8,超声温度范围40~44℃,超声时间为50 min。该方法操作简单,提取时间短,提取效率较高。     

含羞草中总黄酮的提取与分离纯化

确定含羞草中总黄酮的最佳提取部位,并对其初步分离纯化。通过正交试验,分别筛选含羞草根部、茎叶及种子中总黄酮的最优提取条件,比较三者黄酮总含量,最终确定提取部位为茎叶,最佳提取条件:以70%乙醇为溶剂,按照1∶8配料比,在55~58℃下超声50 min。提取液依次用石油醚、乙酸乙酯液液萃取,蒸干上样,用乙醇水溶液以4 m L/min梯度洗脱Diaion HP–20大孔树脂,收集洗脱液并用液相色谱监测每个梯度洗脱液的总黄酮含量,得到分离纯化过的黄酮类物质。当40%乙醇洗脱部位总黄酮含量最高,达57.7%。该工艺确定了含羞草中茎叶部位总黄酮含量最高,大孔树脂初步纯化黄酮类物质有效,为含羞草中黄酮类物质的应用提供了依据。     

珠芽蓼黄酮类化合物清除DPPH·的作用

以六盘水市本地野生的珠芽蓼为原料,利用70%乙醇作为提取介质提取黄酮类化合物,并以抗坏血酸(VC)和维生素E(VE)为对照物,采用DPPH法研究珠芽蓼黄酮提取物对二苯代苦味肼基自由基(DPPH.)的清除作用。结果表明:珠芽蓼黄酮对DPPH.有较强的清除作用,在其质量浓度为368.94μg/mL时,其清除效果最好,清除率达88.96%,显著高于相同浓度下的VC和VE的清除率。珠芽蓼黄酮提取物是一种有前途的抗氧化剂。     

超声波法提取紫甘薯叶总黄酮的工艺研究

采用超声波提取法,以总黄酮含量为考察指标,利用单因素试验法对影响总黄酮提取率的因素进行了分析,然后通过正交试验确定紫甘薯叶总黄酮的最佳工艺条件。研究表明,影响紫甘薯叶总黄酮提取率的主次因素为:溶剂pH值溶剂的浓度料液比提取时间。紫甘薯叶总黄酮的最佳提取工艺为:乙醇体积分数80%,料液比1∶40(W/V),提取时间30 min,提取溶剂pH 9。在此条件下甘薯叶中总黄酮提取率为8.22%。     

Impact of Tea Processing on Tryptophan,Melatonin, Phenolic and Flavonoid Contents in Mulberry (Morus alba L.) Leaves: Quantitative Analysis by LC-MS/MS

Mulberry (Morus alba L.) leaves from two cultivars, Yai-Burirum (YB) and Khunphai (KP), were prepared into green tea (GT) and black tea (BT). Compared to fresh leaf (FL) extract, GT and BT extracts were evaluated for their total phenolic and total flavonoid contents. Total phenolic content (TPCs) in all samples ranged between 129.93 and 390.89 mg GAE/g extract. The processing of tea decreased the levels of TPC when compared to FL extracts in both cultivars. The total flavonoid content (TFCs) in all samples was found in the range of 10.15–39.09 mg QE/g extract and TFCs in GT and BT extracts were higher than FL extracts. The change in tryptophan, melatonin, phenolic and flavonoid contents was investigated by liquid chromatography–mass spectroscopy (LC-MS). The results exhibited that tryptophan contents in all samples were detected in the range 29.54–673.72 µg/g extract. Both GT and BT extracts increased tryptophan content compared to FL extracts. BT extracts presented the highest amounts of tryptophan among others in both cultivars. Phenolic compounds were found in mulberry leaf extracts, including gallic acid, caffeic acid, gentisic acid, protocatechuic acid and chlorogenic acid. Chlorogenic acid presented the highest amount in all samples. Almost all phenolic acids were increased in the processed tea extracts except chlorogenic acid. Rutin was the only flavonoid that was detected in all extracts in the range 109.48–1009.75 mg/g extract. The change in phenolic and flavonoid compounds during tea processing resulted in the change in antioxidant capacities of the GT and BT extracts. All extracts presented acetylcholinesterase enzyme (AChE) inhibitory activity with IC₅₀ in the range 146.53–165.24 µg/mL. The processing of tea slightly increased the AChE inhibitory effect of GT and BT extracts. In conclusion, processed tea from mulberry leaves could serve as a new alternative functional food for health-concerned consumers because it could be a promising source of tryptophan, phenolics and flavonoids. Moreover, the tea extracts also had antioxidative and anti-AChE activities.     

凝胶渗透净化–超高效液相色谱–串联质谱法测定橙汁中链格孢霉毒素

建立橙汁中4种链格孢霉毒素含量测定的凝胶渗透–超高效液相色谱–串联质谱检测方法。样品用乙腈提取后,用填料为Bio-Beads-S–X3的凝胶渗透色谱柱净化,净化时流动相采用乙酸乙酯–环己烷(体积比为1∶1),流速为5 mL/min,测定时用超高效液相反相C18色谱柱分离,甲醇–水系统梯度洗脱,采用电喷雾负离子源和多反应监测(MRM)模式定性和定量。4种链格孢霉毒素的最低定量限在0.0004～0.002 mg/kg范围内,加标回收率为78.9%～111.5%,测定结果的相对标准偏差均低于9.0%(n=10)。     

Characterization and Valorization of the Agricultural Waste Obtained from Lavandula Steam Distillation for Its Reuse in the Food and Pharmaceutical Fields

The main focus of the current research was the characterization of the by-products from the steam distillation of Lavandula angustifolia Mill. (LA) and Lavandula x intermedia Emeric ex Loisel (LI) aerial parts, as they are important sources of bioactive compounds suitable for several applications in the food, cosmetic, and pharmaceutical industries. The oil-exhausted biomasses were extracted and the total polyphenol and flavonoid contents were, respectively, 19.22 ± 4.16 and 1.56 ± 0.21 mg/g for LA extract and 17.06 ± 3.31 and 1.41 ± 0.10 mg/g for LI extract. The qualitative analysis by liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI-MS) revealed that both the extracts were rich in phenolic acids and glycosylated flavonoids. The extracts exhibited radical scavenging, chelating, reducing activities, and inhibitory capacities on acetylcholinesterase and tyrosinase. The IC50 values against acetylcholinesterase and tyrosinase were, respectively, 5.35 ± 0.47 and 5.26 ± 0.02 mg/mL for LA, and 6.67 ± 0.12 and 6.56 ± 0.16 mg/mL for LI extracts. In conclusion, the oil-exhausted biomasses demonstrated to represent important sources of bioactive compounds, suitable for several applications in the food, cosmetic, and pharmaceutical industries.