QuEChERS-GC-MS法快速检测茶叶中的芳樟醇和alpha-紫罗兰酮

【目的】为完善茶叶中香气物质的检测方法,针对芳樟醇与alpha-紫罗兰酮两种香气物质建立气相色谱-质谱联用法(Gas Chromatography-Mass Spectrometry,GC-MS)快速同时检测的分析方法,以期为茶叶中香气物质的检测提供新思路和参考。【方法】茶叶样品经乙腈提取后,用QuEChERS净化管(内含PSA 200 mg、GCB 200 mg、无水硫酸钠400 mg)净化茶叶上清液,采用GC-MS选择离子监测模式进行测定,外标法定量。【结果】芳樟醇和alpha-紫罗兰酮在5.0~2000.0μg·L^(−1)内线性良好,线性相关系数(R^(2))均大于0.999;方法的检出限为分别为0.020 mg·kg^(−1)和0.004 mg·kg^(−1),定量限分别为0.080 mg·kg^(−1)和0.010 mg·kg^(−1)。使用该方法在空白茶叶样品中分别添加3种不同加标浓度(5.0、10.0、1000.0μg·L^(−1))的混合标准溶液,测得平均回收率为88.23%~106.11%,相对标准偏差(RSD)为1.98%~3.25%(n=6)。【结论】该方法操作快速便捷,运行时间仅需16.8 min,重现性和精确度高、灵敏度好,适用于茶叶中芳樟醇、alpha-紫罗兰酮的快速检测,能够为相关机构对茶叶中香气物质的检测提供技术支持。

Alpha-1 antitrypsin deficiency and Pi^(*)Z allele as important co-factors in the development of liver fibrosis

BACKGROUND Alpha-1 antitrypsin deficiency(AATD)is a codominant autosomal hereditary condition that predisposes patients to the development of lung and/or liver disease,and Pi*Z allele is the most clinically relevant mutation.AIM To evaluate the impact of clinical parameters and AATD phenotypes,particularly the Pi*Z allele,in liver fibrosis.METHODS Cross-sectional cohort study including consecutive patients with AATD followed in Pulmonology or Hepatology consultation.RESULTS Included 69 patients,49.3%had Pi*MZ phenotype and 10.1%Pi*ZZ.An age≥55 years,age at diagnosis≥41 years and AAT at diagnosis<77 mg/dL predicted a nonalcoholic fatty liver disease fibrosis score(NFS)not excluding advanced fibrosis[area under the curve(AUC)=0.840,P<0.001;AUC=0.836,P<0.001;AUC=0.681,P=0.025].An age≥50 years and age at diagnosis≥41 years predicted a fibrosis-4 index of moderate to advanced fibrosis(AUC=0.831,P<0.001;AUC=0.795,P<0.001).Patients with hypertension,type 2 diabetes mellitus(DM),dyslipidaemia,metabolic syndrome,and regular alcohol consumption were more likely to have a NFS not excluding advanced fibrosis(P<0.001,P=0.002,P=0.008,P<0.001,P=0.033).Patients with at least one Pi*Z allele and type 2 DM were 8 times more likely to have liver stiffness measurement≥7.1 kPa(P=0.040).CONCLUSION Risk factors for liver disease in AATD included an age≥50 years,age at diagnosis≥41 years,metabolic risk factors,regular alcohol consumption,at least one Pi*Z allele,and AAT value at diagnosis<77 mg/dL.We created an algorithm for liver disease screening in AATD patients to use in primary care,selecting those to be referred to Hepatology consultation.

Predicting pH Optimum for Activity of Beta-Glucosidases

The working conditions for enzymatic reaction are elegant, but not many optimal conditions are documented in literatures. For newly mutated and newly found enzymes, the optimal working conditions can only be extrapolated from our previous experience. Therefore a question raised here is whether we can use the knowledge on enzyme structure to predict the optimal working conditions. Although working conditions for enzymes can be easily measured in experiments, the predictions of working conditions for enzymes are still important because they can minimize the experimental cost and time. In this study, we develop a 20-1 feedforward backpropagation neural network with information on amino acid sequence to predict the pH optimum for the activity of beta-glucosidase, because this enzyme has drawn much attention for its role in bio-fuel industries. Among 25 features of amino acids being screened, the results show that 11 features can be used as predictors in this model and the amino-acid distribution probability is the best in predicting the pH optimum for the activity of beta-glucosidases. Our study paves the way for predicting the optimal working conditions of enzymes based on the amino-acid features.

Predictors for Predicting Temperature Optimum in Beta-Glucosidases

This is the continuation of our studies on beta-glucosidase, which plays an important role in biological processes and recently strong interests focus on their potential role in biofeul production. In order to develop simple methods to predict the optimal working condition for beta-glucosidase, we used a 20-1 feedforward backpropagation neural network to screen possible predictors to predict the temperature optimum of beta-glucosidase from 25 amino-acid properties related to the primary structure of beta-glucosidases. The results show that the normalized polarizability index and amino-acid distribution probability can predict the temperature optimum of beta-glucosidase, which highlights a cost-effective way to predict various enzymatic parameters of beta-glucosidase.

Antioxidant,anti-alpha-glucosidase and pancreatic beta-cell protective effects of methanolic extract of Ensete superbum Cheesm seeds

Objective: To investigate the antioxidant, anti-a-glucosidase and pancreatic b-cell protective potential of Ensete superbum(E. superbum) seeds.Methods: A variety of in vitro assays including radical scavenging, reducing power potential, phenolic content determination, a-glucosidase assay and pancreatic b-cell(1.4E7 cells) viability were employed for assessing the effect of methanolic extract of E. superbum seeds.Results: The radical scavenging and reducing power effects comparable with the standard rutin were obtained while the enzyme inhibitory activity of the extract was 68-fold better than the standard antidiabetic drug, acarbose. The seed extract of E. superbum was packed-full of polyphenols with mean percentage gallic acid equivalent value of(38.2 ± 1.8)(n = 3). The protection of pancreatic cells from massive onslaught of hydrogen peroxide was far superior to that obtained for rutin.Conclusions: The reputed antidiabetic therapeutic uses of the seeds extract of E. superbum may be justified on the basis of inhibition of carbohydrate enzymes, antioxidant effects and pancreatic b-cell protection.

Is Alpha-Glucosidase Inhibition a Mechanism of the Antidiabetic Action of Garlic (<i>Allium sativum</i>)?

Objective: There has been a global surge in the number of diabetic cases. Many of the agents used as antidiabetic are either expensive or have side effects. Researchers are now turning their attention to phytotherapy as a viable alternative in the treatment of hyperglycemia. The aim of this study was to examine the inhibition of α-glucosidase as a possible mechanism of antidiabetic action of garlic. Method: The inhibitory effect of different concentrations of garlic was examined for alpha-glucosidase inhibitory activity in a 96-well micro plate. Saccharomyces cerevisiae was used as the source of alpha-glucosidase and the assay was analyzed with a Thermo Scientific? Multiskan Spectropho-meter at an absorbance of 400 nm. Result: The extracts of garlic exhibited a dose-dependent inhibition of alpha-glucosidase in comparison to acarbose. The IC50 of acarbose was 3.19 ± 0.42 mg/ml, for garlic, the IC50 was 16.93 mg/ml. Conclusion: In this study, garlic oil showed some promise as an antidiabetic agent with a mechanism of action similar to acarbose and miglitol that are currently used as antidiabetics. It is hoped that carrying out further research on garlic will elucidate other mechanisms of action.

Homology Modeling of Human Alpha-Glucosidase Catalytic Domains and SAR Study of Salacinol Derivatives

Maltase-glucoamylase (MGAM) and sucrase-isomaltase (SI) belong to human intestinal alpha-glucosidase and their N-terminal side catalytic domains are called NtMGAM and NtSI, and their C-terminal side catalytic domains are called CtMGAM and CtSI. As an antidiabetic, alpha-glucosidase inhibitor is required to bind to all of these domains to inhibit disaccharides hydrolysis. Salacinol and kotalanol isolated from Salacia reticulata are novel seed compounds for al-pha-glucosidase inhibitor. Even though the complex structures of NtMGAM or NtSI have been determined experimen-tally, those of CtMGAM and CtSI have not been revealed. Thus, homology modeling for CtMGAM and CtSI has been performed to predict the binding mode of salacinol and its derivatives for each domain. The binding affinities for these compounds were also calculated to explain the experimental structure-activity relationships (SARs). After a docking study of the derivatives to each catalytic domain, the MM/PBSA method has been applied to predict the binding affinities. The predicted binding affinities were almost consistent with the experimental SARs. The comparison of the complex structures and binding affinities provided insights for designing novel compounds, which inhibit all catalytic domains.

Computational Study on the Comparative Differences in the Activity of Inhibitors of Human versus Rat Alpha-Glucosidase

Differences between the inhibitory activities of specific compounds on analogous enzymes isolated from different animal species are one of the critical issues to evaluate when exploring structure-activity relationships. The activity of acarbose is about ten times stronger in rat than in human, and that of neosalacinol is similar in both species. Binding affinities of acarbose and neosalacinol to four catalytic domains of alpha-glucosidases in human and rat were compared to investigate the cause of activity differences among species. Species difference was brought about complicatedly by the balance of interaction with four domains, and the result was indicated that larger ligand would show larger species difference in activity.

长链非编码RNA alpha-2-巨球蛋白反义RNA 1靶向微小RNA-106b-5p调控氧化型低密度脂蛋白诱导的人脑微血管内皮细胞损伤

目的探讨长链非编码RNA(lncRNA)alpha-2-巨球蛋白反义RNA 1(A2M-AS1)靶向微小RNA(miR)-106b-5p对氧化型低密度脂蛋白(ox-LDL)诱导的人脑微血管内皮细胞损伤的影响。方法用ox-LDL诱导人脑微血管内皮细胞设为ox-LDL组,正常培养细胞为对照(Ctrl)组;A2M-AS1过表达(pcDNA-A2M-AS1组)、空载体(pcDNA组)、miR-106b-5p抑制剂(anti-miR-106b-5p组)、阴性对照(anti-miR-NC组)、pcDNA-A2M-AS1与对照mimic NC(miR-NC组)、pcDNA-A2M-AS1与miR-106b-5p模拟物(miR-106b-5p mimics组)转染细胞后加ox-LDL处理,n=9;Real-time PCR检测A2M-AS1与miR-106b-5p表达;试剂盒检测丙二醛(MDA)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)水平;流式细胞术及TUNEL法检测细胞凋亡;双荧光素酶报告基因实验检测A2M-AS1与miR-106b-5p靶向关系;Western blotting检测Bcl-2和Bax蛋白表达量。结果与Ctrl组比较,ox-LDL组A2M-AS1表达水平、SOD和CAT活性、Bcl-2蛋白水平降低,miR-106b-5p表达水平、MDA水平、凋亡率、Bax蛋白水平升高(P<0.05);过表达A2M-AS1或干扰miR-106b-5p降低ox-LDL诱导细胞后MDA水平、凋亡率与Bax蛋白水平,升高SOD、CAT活性和Bcl-2蛋白水平(P<0.05);A2M-AS1靶向miR-106b-5p;上调miR-106b-5p逆转过表达lncRNA A2M-AS1对ox-LDL诱导的人脑微血管内皮细胞损伤的作用。结论A2M-AS1通过靶向miR-106b-5p减轻ox-LDL诱导的人脑微血管内皮细胞损伤。

Study of the Effect of Zhuang Medicine Aponeurotic System Triple Therapy on Lumbar Disc Herniation and Alpha-1 Acid Glycoprotein Level

Objective:To analyze the application effect of Zhuang medicine aponeurotic system triple therapy in the treatment of lumbar disc herniation and its effect on the level of alpha-1 acid glycoprotein(alpha-1 AGP).Methods:200 patients with lumbar disc herniation were selected and randomly divided into a treatment group and a control group,100 cases in each group.The control group was given conventional acupuncture,and the treatment group was treated with manipulation+fire needling+cupping.The alpha-1-AGP levels before and after treatment,as well as the lumbar spine function and pain scores before and after treatment,and the adverse reactions occurred during treatment between the two groups were compared.Results:Before treatment,there was no significant difference in alpha-1 AGP levels,lumbar function,and pain scores between the two groups(P>0.05).After treatment,the lumbar function scores of the two groups were significantly increased,with the treatment group having higher scores than the control group(P<0.05);the incidence of adverse reactions in the treatment group was 2.00%,which was much lower than the control group(P>0.05).Conclusion:Appropriate application of Zhuang medicine aponeurotic system triple therapy in the clinical treatment of lumbar disc herniation can promote the improvement of alpha-1 AGP index level,reduce the pain degree of patients,and improve their lumbar spine function.At the same time,Zhuang medicine also has significant advantages in terms of safety,while ensuring the efficacy and safety of the treatment.

疏绵状嗜热丝孢菌β-葡萄糖苷酶的基因组挖掘与表达

基因组挖掘是发现生物催化剂的高效工具,开发热稳定性β-葡萄糖苷酶具有重要的应用价值.该文采用基因组挖掘策略,从嗜热真菌疏绵状嗜热丝孢菌的基因组中挖掘出7个注释为β-葡萄糖苷酶基因或β-葡萄糖苷酶预测蛋白基因,其中TLG-1、TLG-2、TLG-4、TLG-5、TLG-6属于GH3家族,TLG-3和TLG-7分别属于GH1家族和GH17家族,且TLG-7与GenBank数据库已有序列的同源性很低,只有48.43%.选择同源性低的、同源序列被研究少的TLG-2、TLG-5、TLG-6和TLG-7进行基因克隆和毕赤酵母异源表达,重组毕赤酵母经甲醇诱导表达后,用发酵液上清进行SDS-PAGE分析,结果表明TLG-2、TLG-5、TLG-6和TLG-7均成功分泌表达.对发酵液进行β-葡萄糖苷酶活力测定结果表明:TLG-2的活力最高,达到166.6 U·mL^(-1);其次是TLG-5的活力,其值为79.8 U·mL^(-1),TLG-6和TLG-7的活力较低,分别为9.9 U·mL^(-1)和9.5 U·mL^(-1).研究结果为疏绵状嗜热丝孢菌β-葡萄糖苷酶的应用奠定了基础.

13例晚发型庞贝病临床特征分析

目的探讨晚发型庞贝病(LOPD)患者的临床特征和基因突变特点。方法选取2020年9月至2023年12月在浙江大学医学院附属第一医院确诊为LOPD的13例患者,对所有患者进行临床调查、GAA活性检测和GAA基因检测。结果13例患者中男7例,女6例;家系患者5例,散发患者8例;中位发病年龄17岁(8~52岁),中位就诊年龄24岁(10~52岁),中位确诊年龄31岁(14~58岁)。患者首发症状,10例患者表现为肢体无力,3例患者表现为呼吸困难。血清肌酸激酶平均水平552 U/L(55~1084 U/L),1例患者血清肌酸激酶水平正常。13例患者均有脊柱侧弯、不同程度限制性通气功能障碍。9例患者行神经电生理检查均提示肌源性损害,其中8例患者有临床下肌强直放电。GAA活性平均值0.3μmol/(L·h)[0.17~0.5μmol/(L·h)]。共检出GAA基因13个变异位点,最常见突变位点c.2238G>C(p.W746C)。发现c.543del(p.F181Lfs*40)、c.839_840insCC(p.R281Pfs*34)、c.1800_1823del(p.S601_R608del)、c.2296T>C(p.Y766H)、c.995C>A(p.S332*)共5个新变异位点。结论LOPD是一种容易延误诊断的罕见病。肢体近端无力、呼吸功能下降、肌酸激酶轻中度升高、脊柱侧弯、肌电图提示临床下肌强直放电是LOPD的高危“画像”。c.2238G>C(p.W746C)是其热点突变,新发现的5个GAA变异位点丰富了GAA基因突变谱系。

非酿酒酵母的选育及其改善枸杞酒香气品质的研究

枸杞酒香气不足以及典型性不突出等问题限制了枸杞发酵酒行业的发展。从‘宁杞5号’枸杞果和果园土壤中得到26株非酿酒酵母,筛选出6株产β-葡萄糖苷酶(β-D-Glucosidase,β-G)能力较强的非酿酒酵母,通过生长曲线测定以及乙醇、渗透压耐受性测定探究其生理特性,优选出异常威克汉姆酵母(Wickerhamomyces anomalus)Y11与酿酒酵母M-23-7-14混合发酵枸杞酒,以常规理化指标、风味物质和感官品质为指标分析枸杞酒品质。结果表明,当酿酒酵母M-23-7-14与异常威克汉姆酵母Y11按接种量10∶1接种,且先接种异常威克汉姆酵母Y11,间隔12 h接种酿酒酵母M-23-7-14时,体系发酵性能最优。相较于纯种发酵,混菌发酵时枸杞酒风味物质的总质量浓度提高了21.7%,其中酯类物质的质量浓度比纯种发酵提高了85.8%。该研究为枸杞发酵酒行业提供了优良酵母,并优化了枸杞酒的发酵工艺,提升了枸杞酒香气品质,为工业化生产提供了理论支持。

红小豆提取物对α-葡萄糖苷酶和胰脂肪酶的抑制作用

采用体积分数70%乙醇对红小豆进行提取,提取物经水混旋,然后依次采用石油醚、乙酸乙酯、正丁醇溶剂萃取。正丁醇萃取相浓缩干燥后经AB-8大孔树脂吸附,以不同体积分数乙醇洗脱,测定洗脱相浓缩液中总三萜皂苷和总黄酮的含量,并探究洗脱相浓缩液对α-葡萄糖苷酶和胰脂肪酶的抑制作用。结果显示:体积分数70%和95%乙醇洗脱组分中的总三萜皂苷含量高于其他组分,且体积分数70%乙醇洗脱组分的总黄酮含量最高,为(181.83±3.09)mg/g;体积分数95%、70%、50%乙醇洗脱组分对α-葡萄糖苷酶和胰脂肪酶均具有较好的抑制活性;体积分数95%乙醇洗脱组分对2种酶的抑制类型均为混合型抑制。

青钱柳叶化学成分及其α-葡萄糖苷酶抑制活性研究

目的 研究青钱柳Cyclocarya paliurus(Batal.) Iljinskaja叶的化学成分及其α-葡萄糖苷酶抑制活性。方法 青钱柳叶95%乙醇提取物采用大孔树脂、硅胶、Sephadex LH-20、聚酰胺、C18反相硅胶及半制备HPLC进行分离纯化,根据理化性质及波谱数据鉴定所得化合物的结构。采用PNPG法评价其α-葡萄糖苷酶抑制活性。结果 从中分离得到15个化合物,分别鉴定为cyclopaloside C(1)、cyclopaloside A(2)、juglanosides E(3)、vaccinin A(4)、ent-mururin A(5)、山柰酚-3-O-α-L-鼠李糖苷(6)、山柰酚-3-O-β-D-葡萄糖苷(7)、山柰酚-3-O-β-D-葡萄糖醛酸甲酯(8)、山柰酚-3-O-β-D-葡萄糖醛酸乙酯(9)、山柰酚-3-O-β-D-葡萄糖醛酸丁酯(10)、槲皮素-3-O-α-L-鼠李糖苷(11)、槲皮素-3-O-β-D-葡萄糖苷(12)、槲皮素-3-O-β-D-半乳糖苷(13)、槲皮素-3-O-β-D-葡萄糖醛酸丁酯(14)、香橙素(15)。总提取物抑制α-葡萄糖苷酶的IC_(50)值为(1.83±0.04)μg/mL,化合物1、4~5分别为(29.48±1.86)、(0.50±0.07)、(0.71±0.07)μmol/L。结论 化合物1为新四氢萘醇苷类,化合物4~5、8~10、14为首次从青钱柳叶中分离得到。化合物4~5为较少见的黄酮木脂素类化合物,对α-葡萄糖苷酶具有潜在的抑制活性。

鸦胆子石油醚提取物成分分析及降糖活性初探

目的:对鸦胆子石油醚提取物的主要成分进行分析,并对其降糖活性进行探讨。方法:采用石油醚萃取的方式提取鸦胆子,应用气相色谱-质谱联用技术(GC-MS)鉴定其成分,应用归一化法测定各成分的质量分数(相对含量)。色谱条件:色谱柱Agilent HP-5MS(30 m×250μm×0.25μm),流速1 mL/min,分流比15∶1,进样口温度300℃。程序升温条件:60℃保持5 min,以4℃/min升温至180℃,保持5 min,以2℃/min升温至280℃,保持10 min。质谱条件:离子源电子轰击(EI)源,离子源温度230℃,四级杆温度150℃,溶剂延迟3 min,电子能量70 eV,质荷比(m/z)范围50~900。数据库:NIST 08。降糖活性通过测试pNPG水解产物NPG的吸光计算而得。结果:从鸦胆子石油醚提取物成分中鉴定出脂肪酸、芳香酸、脂肪酸酯、醛、酮、萜、类固醇、烃类等53种成分,其中脂肪酸11种,脂肪酸酯20种,醛7种,烃9种,芳香酸1种,酮1种,萜1种,类固醇2种,生育酚1种。药理学研究表明,鸦胆子石油醚提取物具有α-葡萄糖苷酶抑制活性。结论:GC-MS能够高效准确快速鉴定鸦胆子石油醚提取物的化学成分,鸦胆子这一类成分的降血糖作用为进一步研究其作用机制奠定了基础。

智能手机辅助双探针比色法检测α-葡萄糖苷酶

该文以3,3',5,5'-四甲基联苯胺(TMB)和罗丹明B为比色探针,建立了α-葡萄糖苷酶的比色检测方法,并在此基础上基于智能手机策略,通过RGB值对α-葡萄糖苷酶进行检测。结果表明,Fe^(3+)-TMB-罗丹明B显色体系的吸光度与α-葡萄糖苷浓度在20~100 U/L范围内呈线性关系,检出限为3.3 U/L。采用photo⁃shop软件分析样品图像和样品荧光图像的RGB值,其与α-葡萄糖苷酶浓度在10~100 U/L范围内呈线性关系,检出限分别为2.5 U/L和1.2 U/L。该法已成功用于α-葡萄糖苷酶抑制剂阿卡波糖抑制率评估和胎牛血清中α-葡萄糖苷酶浓度的测定。所构建的智能手机辅助检测法为α-葡萄糖苷酶的临床分析和酶抑制剂的快速筛选提供了简便、快捷和准确的方法。

皖浙花猪干腌火腿源血糖调节肽的分离纯化、鉴定及量子化学表征

为探究小肽抑制糖类消化的机理,制备皖浙花猪干腌火腿肌肉的水提物和胃胰酶消化产物,分离纯化出α-淀粉酶和α-葡萄糖苷酶抑制活性较高的组分,鉴定、筛选其中的肽序列,采用量子化学方法计算分子前线轨道分布和能量、静电荷分布、键长等结构和电荷参数,推测活性位点。结果表明:1)酶解后火腿肌肉的粒径减小、降糖活性提高;2)水提物和胃胰酶消化产物经过葡聚糖凝胶分离后分别获得两个组分(S-Ⅰ、S-Ⅱ)和3个组分(WY-Ⅰ、WY-Ⅱ和WY-Ⅲ);3)利用质谱技术从高活性组分WY-Ⅱ中鉴定出104条长度8~24的肽序列,筛选出Peptide Ranker程序评分大于0.7的5条序列;4)前述序列的最高占据轨道多分布在精氨酸的胍基及氨基端附近基团,而最低未占轨道多分布在羧基端及附近基团;5)能级差ΔEL-H较低的序列GPMGPSGPR、LGFGGPSGPNAGR、APAPAPAPAPAPPK可能具有较高活性。根据库伦定律,其活性位点分别定位于精氨酸的C106H108、亮氨酸的C10H12和赖氨酸的C176H177,都位于C—H键。研究为探究肽的血糖调节机制,证明地方品种猪的营养价值提供了理论支撑。

连续7年施肥提升复垦土壤肥力提高玉米产量的驱动因子

研究长期施肥对玉米连作体系下采煤塌陷区复垦土壤肥力变化和玉米产量的影响,明确玉米产量提高的驱动因素和最佳施肥处理,可为该区域培肥土壤和耕地质量提升提供理论依据。该研究依托7 a(2014—2020年)复垦定位肥料试验基地,设置不施肥对照(CK)、氮磷钾平衡施肥(NPK)、单施有机肥(M)和有机肥配施无机肥(MNPK)4个处理,采集0~20 cm土层土壤样品,研究不同施肥处理对作物产量、土壤化学指标(包括有机质、全氮、有效磷、速效钾、有效铁锰铜锌含量)、土壤物理指标,即团聚体分布比例及其碳氮含量以及土壤生物指标,即与碳循环相关的土壤酶活性的影响。结果表明,施化肥及有机肥较CK均显著提高了玉米籽粒产量,且以M处理的增幅最大。M处理显著提高了土壤有机质、全氮、速效钾及有效锰含量,增幅分别为21.50%、12.50%、98.37%及20.19%;MNPK处理改善了土壤的基本性质,显著提高了大粒径团聚体(>2 mm)中有机碳和全氮含量,增幅分别达68.68%和471.43%,但是显著降低了土壤有效铜和有效锌含量,降幅分别为16.67%和16.46%。而且施加有机肥后,加速了大团聚体(0.25~2 mm)的破碎,伴随着粉黏粒组分(<0.053 mm)数量的增加。此外,NPK处理显著提高了β-葡萄糖苷酶活性,增幅为29.17%,但是显著降低了脲酶活性,降幅为29.79%,施有机肥(M和MNPK)显著提高了蔗糖酶、β-葡萄糖苷酶、脲酶和碱性磷酸酶活性,增幅分别为45.87%~73.39%、54.98%~60.73%、43.09%~80.32%和51.52%~54.97%。进一步通过主成分分析以及土壤肥力综合指数评价,表明单施有机肥是该复垦区域耕地质量提升和维持土地生产力较好的农田管理措施。结合冗余分析结果可知,β-葡萄糖苷酶是评价土壤肥力的敏感性指标,它对玉米籽粒产量和土壤有机质含量的贡献率高达72.40%。因此,在现有的农田管理条件下,单施有机肥主要通过增强β-葡萄糖苷酶活性进而促进复垦土壤肥力的形成,最终提高了作物产量,是维持该复垦区作物高产稳产和培育耕地质量的有效措施。

昆布多糖的复合酶法提取工艺优化及其对α-葡萄糖苷酶的抑制活性

优化复合酶提取昆布多糖的工艺参数,并考察其抑制α-葡萄糖苷酶的能力。以昆布多糖得率为评价指标,通过正交试验确定复合酶配比,采用响应面法评价酶解时间、pH、液料比和温度对昆布多糖得率的影响。采用体外酶抑制实验测定昆布多糖对α-葡萄糖苷酶的抑制活性。结果表明,复合酶最佳添加量为纤维素酶100 mg、果胶酶90 mg、木瓜蛋白酶55 mg,最佳酶法提取工艺为酶解时间1.8 h、酶解温度49.4℃、pH6.1、液料比59:1 mL/g,最佳工艺条件下昆布多糖预测得率18.183%,实测多糖得率18.19%±1.04%,其中性糖、酸性糖、蛋白质及硫酸根含量分别52.72%、11.76%、2.66%、19.49%;在1~5 mg/mL范围内其对α-葡萄糖苷酶的抑制作用随浓度增加而升高,最大抑制率为79.04%±3.17%,IC50为1.443 mg/mL。复合酶法提取的昆布多糖得率高,其对α-葡萄糖苷酶具有明显的抑制作用。