杜仲雄花正丁醇提取物抑菌活性研究

为探讨杜仲雄花正丁醇提取物的抑菌活性,以大肠杆菌、枯草芽孢杆菌、金黄色葡萄球菌、炭疽杆菌、根霉、青霉和黑曲霉为供试菌种,采用打孔法和倍比稀释法,检测杜仲雄花正丁醇粗提物及经过硅胶柱分离得到的7种不同极性提取物对真菌和细菌的抑菌活性,并确定最小抑菌浓度(MIC),分析粗提物及7种分离产物的活性。结果显示,杜仲雄花正丁醇粗取物对金黄色葡萄球菌和炭疽杆菌具有较好的抑菌作用,MIC分别为0.007 8g/mL和0.015 6g/mL;杜仲雄花正丁醇粗提物对枯草芽孢杆菌、大肠杆菌、根霉、黑曲霉和青霉没有抑制作用。然而经过硅胶柱进一步分离发现,经过分级提取的样品4和样品5对黑曲霉出现了抑制作用,对金黄色葡萄球菌、炭疽杆菌、和枯草芽孢杆菌等革兰氏阳性菌的抑制作用明显增强。说明杜仲雄花正丁醇粗提物经过硅胶柱的分离能够得到对不同菌株的特异抑菌物质,这为寻找不同菌种的抑菌活性物质提供了参考依据。     

白骨壤提取物抑菌活性研究

以白骨壤叶为原料,以4种常见病原菌为供试菌种,采用生物活性追踪法研究了白骨壤叶提取物的抑菌活性。利用滤纸片扩散法对白骨壤叶不同溶剂提取物进行初步抑菌试验,确定出抑菌活性成分所在部位,并对有效部位的有效成分进行纯化、定性检测和抑菌试验。结果表明,95%乙醇提取液对4种病原菌都有较强的抑菌效果,石油醚稍有抑菌作用,水提液无抑菌作用。利用大孔吸附树脂对抑菌活性较强的乙醇提取液进行进一步分离,得到2个抑菌活性组分,它们对4种试验菌的抑菌效果与浓度呈正相关关系。纯化物对4种供试菌的抑菌大小顺序为大肠杆菌>根霉>枯草芽孢杆菌>金黄色葡萄球菌,初步的定性试验结果表明,有抑菌活性的纯化物中含有生物碱、黄酮、蒽醌等。     

金橘黄酮抑菌作用研究

探讨金柑黄酮的抑菌作用。以金橘黄酮为受试物,研究其活性成分对大肠杆菌,枯草芽孢杆菌、金黄色葡萄球菌、黑曲霉、青霉、毛霉的抑制作用。金橘黄酮对供试菌株的抑制效果顺序为：金黄色葡萄球菌〉枯草杆菌〉大肠杆菌〉毛霉,对青霉、黑曲霉没有抑菌作用。最小抑菌浓度分别为0．63,1．25,1．25,2．50mg／mL。最小杀菌浓度为1．25,2．50,2．50,2．50mg／mL。抑菌率随作用时间延长而增加,对4种供试菌株的半抑菌率时间（IT50）分别为4．65,5．70,6．74,9．71h。     

核桃青皮提取物抑菌活性及抑菌机理研究

用石油醚、氯仿、乙酸乙酯和正丁醇等不同极性有机溶剂对核桃青皮乙醇提取物进行萃取,以7种细菌为供试菌,采用离体实验方法对核桃青皮乙醇提取物的不同极性萃取相进行抑菌作用研究并探讨其作用机理。结果表明:各萃取相对供试细菌均有一定抑制作用:乙酸乙酯相氯仿相正丁醇相石油醚相。乙酸乙酯萃取相对7种细菌均有较好抑制效果,具有广谱抑菌作用。在浓度为50 mg/m L时,乙酸乙酯萃取相抑菌效果最好,对金黄色葡萄球菌的抑菌圈直径达到19.94 mm,对其最低抑菌浓度(MIC)和最低杀菌浓度(MBC)分别为0.781和1.563 mg/m L。乙酸乙酯萃取相对温度和紫外线的耐受力较强,抑菌作用受p H影响较大,Na Cl和蔗糖的添加对菌体生长也有一定抑制。其抑菌机理主要是破坏菌体的细胞壁或膜的结构。     

核桃青皮提取物对几种采后病原真菌抑制作用的研究

采用生长速率法和孢子萌发法,研究了核桃青皮乙醇提取物对几种主要的采后致病真菌青霉菌(Penicillium citrinu)、匍枝根霉(Rhizopus stolonifer)、灰葡萄孢(Botryis cinerea)、镰刀菌(Fusarium oxysporum)和交链孢属(Alternaria)的抑制效应,确定其最低抑菌浓度和最低杀菌浓度。结果表明,核桃青皮提取物对供试菌种均有明显的抑制效果,提取物浓度为20mg/mL时,对5种供试菌种菌丝生长和孢子萌发的抑制率均达到88%以上。不同浓度提取物对相同病原菌的抑制效果差异显著(p0.05),且随着浓度的增加抑制作用增强;提取物对5种孢子萌发的EC50值分别为:4.6384、10.2419、11.7834、8.3486和9.4516mg/mL,供试菌种菌丝的EC50值分别为:9.8142、11.6084、17.2737、10.1965和8.2892mg/mL。     

干燥方式对核桃青皮胡桃醌含量与抑菌性能的影响

为考察核桃青皮抑菌活性与干燥方式的关系,以大肠杆菌、金黄色葡萄球菌和石榴干腐病菌为供试菌,评价了自然干燥(P_1)、烘干(P_2)及真空冷冻干燥(P_3)核桃青皮的抑菌活性。结果显示,3种样品对3种供试菌均有较强的抑制作用,并呈现剂量依赖效应,即M_1M_2M_3(M_1,M_2,M_3浓度分别为100、80和60 mg/m L的核桃青皮萃取液),3种干燥方式间比较均表现为P_3P_2P_1;P_1、P_2和P_3对大肠杆菌和石榴干腐病菌的最小抑菌浓度(MIC)结果一致,分别为20、15和10 mg/m L,对金黄色葡萄球菌的MIC分别是15、10和5 mg/m L;P_1、P_2和P_3样品中胡桃醌的含量分别是8.04、9.46和11.84 mg/g,与其抑菌活性呈极显著正相关(p0.01)。表明干燥方式会影响核桃青皮中胡桃醌含量及抑菌活性,其中真空冷冻干燥是一种理想的干燥方式。     

黑果枸杞果实提取物的抑菌效果研究

以野生黑果枸杞果实为原料,分别用95%乙醇和水浸提黑果枸杞果实中的抑菌成分,研究黑果枸杞提取液对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、青霉、黑曲霉、啤酒酵母6种菌的抑菌效果,并用抑菌效果较好的醇提液进行供试菌的最小抑菌浓度试验;研究pH、温度对提取液抑菌效果的影响。结果表明:黑果枸杞的醇提液和水提液均对以上细菌、霉菌、酵母菌有一定的抑菌效果,且对细菌的抑菌效果优于霉菌和酵母菌;醇提液的抑菌效果比水提液的抑菌效果好;醇提液对不同菌种的最小抑菌浓度有所不同,其中对黑曲霉和啤酒酵母的最小抑菌浓度是1g/mL,对青霉的最小抑菌浓度是0.5 g/mL,对大肠杆菌和枯草芽孢杆菌的最小抑菌浓度是0.125 g/mL,而对金黄色葡萄球菌的是0.062 5 g/mL;提取液在酸性条件下抑菌效果显著,高温长时间处理可降低其抑菌活性。     

沙棘果皮渣黄酮抑菌活性研究

考查沙棘果皮渣黄酮对于大肠杆菌、金黄色葡萄球菌、酵母菌、变形杆菌、产气杆菌、嗜热链球菌、枯草芽孢杆菌、根霉、青霉和黑曲霉等几种主要危害食品卫生、安全菌种的抑制作用,并对其最低抑菌浓度进行测定。结果表明:沙棘果皮渣黄酮对大肠杆菌、金黄色葡萄球菌、酵母菌、变形杆菌、嗜热链球菌、枯草芽孢杆菌、根霉、青霉、黑曲霉均有明显抑菌效果,对各个菌种的最低抑菌浓度分别为5、20、40、40、80、5、2.5、20、10mg/mL。     

黄花蒿挥发油的体外抑菌活性研究

采用水蒸气蒸馏法提取黄花蒿挥发油,通过体外抑菌实验,利用纸片法和试管法分别测定其抑菌活性和最低抑菌浓度(MIC)。比较黄花蒿挥发油对12 种常见细菌和真菌的抑菌活性。结果表明：黄花蒿挥发油对12 种实验菌表现出不同的抑制活性。真菌对黄花蒿挥发油具有更强的敏感性。黄花蒿挥发油对真菌的抑制作用比较稳定,由强到弱依次为黑曲霉、啤酒酵母菌、产黄青霉、马青霉、毛霉、青霉和根霉。     

采收时间对核桃青皮成分和功能活性的影响

目的探究采收期对新鲜核桃青皮的化学成分、抗氧化和抗菌特性的影响。方法以不同采收成熟度(1P:2017.8.20、2P:2017.8.26、3P:2017.9.1)的"香铃"核桃为实验材料,手工脱除新鲜的核桃青皮,通过测定不同采收成熟度所得青皮中的胡桃醌、总酚、黄酮、水解单宁的含量,抗氧化和抗菌活性,以探讨采收期对新鲜核桃青皮的影响。结果随着采收成熟度的增加,核桃青皮中的抗氧化活性呈现上升趋势;总酚和水解单宁的含量先上升后趋于平稳。其中,第二成熟度(2P)采收的核桃青皮中,胡桃醌和黄酮的含量最高,分别为0.58 mg/g FW、2.67 mg/g FW。所有成熟度所得核桃青皮水提物,对革兰氏阳性菌有不同程度的抑制。第三成熟度(3P)所得核桃青皮水提物对枯草芽孢杆菌的抑菌圈直径达到了1.35 cm。结论第二、三成熟度采收的核桃青皮,含有丰富的活性成分,且具有良好的抗氧化和抗菌活性。     

核桃青皮提取液与壳聚糖复合物对甜瓜采后品质的影响

利用核桃青皮提取液与壳聚糖复配制备出一系列不同配比的复合物溶液,应用于新疆甜瓜的保鲜实验。分析3 种不同配比复合物溶液对甜瓜采后贮藏品质及生理指标的影响。结果表明,在温度25 ℃、相对湿度55%～60%条件下,核桃青皮提取液-壳聚糖复合物能够有效地降低甜瓜的发病率、质量损失率和呼吸强度,减少甜瓜中可溶性固形物和可滴定酸含量的降低,促进多酚氧化酶和过氧化物酶的活性,保持甜瓜中苯丙氨酸解氨酶的活性,但其对甜瓜硬度的影响不明显。核桃青皮提取液含量较高的CHE-25复合物溶液在甜瓜采后贮藏多个生理指标和酶活性等因素上表现均优于其他组,其保鲜作用效果最优,说明核桃青皮提取物可作为天然保鲜剂应用于甜瓜采后贮藏保鲜。     

Recovery of bioactive compounds from walnut (Juglans regia L.) green husk by supercritical carbon dioxide extraction

In this work, the use of supercritical carbon dioxide, a nontoxic solvent, was proposed to extract bioactive compounds from Juglans regia L. green husk and was compared to other traditional techniques based on solvents such as ethanol, methanol and water. Supercritical CO₂ was combined with ethanol as an organic modifier at a rate of 20% of the total flow to achieve greater extraction of polar compounds. The extracts were characterised in terms of extraction yields, antioxidant activity, total polyphenol content, phenolic acids, juglone, volatile organic compounds and antifungal activity. The results showed that the extracts obtained with supercritical CO₂ were rich in polyphenols (10750 mg GAE/100 g) and juglone (1192 mg/100 g) and exerted high antioxidant activity and antifungal activity compared with the tested fungi. Walnut green husk is not just a food industry waste but also an important economic source of bioactive compounds that could be used for food active packaging.     

The antioxidant activities and the xanthine oxidase inhibition effects of walnut (Juglans regia L.) fruit,stem and leaf

The antioxidant activities and xanthine oxidase inhibition effects of walnut fruit, stem and leaf were studied in this work. The total phenolic contents were in a descending sequence: shell extract > leaf extract > stem extract > defatted walnut kernel (DWK) extract > green husk extract (GHE). The sequence of total phenolic contents was in agreement with the sequence of antioxidant capacities evaluated by ferric reducing antioxidant power and oxygen radical absorbance capacity (ORAC) assays except for DWK extract. The walnut shell extract showed the highest phenolic content (14.81 gallic acid equivalent g/100 g dry extract) and the best antioxidant activity (the ORAC value was 3423.44 ± 142.52 μmol Trolox equivalents g^?1). All tested samples possessed xanthine oxidase inhibitory (XOI) effects, the inhibition percentages of which were >50% at 2 mg mL^?1 except for stem and DWK extracts. The contents of the major compound (hydrojuglone) in all extracts were in a descending order: GHE > walnut stem extract > walnut shell extract > walnut leaf extract > DWK extract.     

不同干燥方式对核桃青皮活性物质含量和生物活性的影响

目的研究不同干燥方法对核桃青皮提取物的生物活性物质含量、抗氧化活性和抑菌活性的影响。方法分别采用Folin-Ciocalteu法、硝酸铝显色法和分先先度法测定核桃青皮提取物的多酚含量、黄酮含量和单宁含量;采用自由基清除法和三价铁离子还原法测定抗氧化活性;采用抑菌圈法、最低抑菌浓度值法(minimum inhibitory concentration,MIC)和最低杀菌浓度值法(minimum bactericidal concentration,MBC)测定抑菌活性。结果真空冷冻干燥后的提取物的生物活性成分保留量最大,1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除能力和铁还原能力(ferric reducing antioxidant power,FRAP)均最强,对革兰氏阳性菌的抑制作用强于革兰氏阴性菌;自然干燥后的提取物清除2,2-联氮-二(3-乙基-苯幵噻唑-6-磺酸)二铵盐(2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate),ABTS)自由基的能力最强;红外干燥后的提取物对革兰氏阴性菌的抑制作用强于革兰氏阳性菌。结论不同干燥方式对核桃青皮提取物的生物活性物质的含量和活性均有不同的影响     

核桃青皮的成分与药理研究进展

简述了核桃青皮的化学成分及药理作用的研究进展。药理研究证明,核桃青皮具有抑菌、镇痛、抗肿瘤等功能。为进一步研究、开发和利用我国丰富的核桃青皮资源提供了思路和方法,具有一定的指导意义。     

Phenolics from walnut (Juglans regia L.) kernels: Antioxidant activity and interactions with proteins

Walnut (Juglans regia L.) kernels have important amounts of phenolic compounds. The objectives of the work were twofold: (a) to extract the phenolic fraction from hulls and walnut flour, and to examine its antioxidant capacity and (b) to evaluate the effect of hull removal on solubility of protein fractions from walnut flour. In accordance with their higher total phenolic content, hull extracts had stronger antioxidant activity than had flour extracts. The presence of phenolic compounds decreased protein solubility in walnut flour obtained from whole kernels. Dehulling of kernels significantly improved protein recovery but this result was strongly affected by the solvent system employed. Proteins from whole kernels, especially those extracted with water and NaCl solution, had a reduced solubility, indicating that phenolics bind to proteins when they are dispersed in aqueous media at neutral pH. The results are discussed in the light of the different complex-forming mechanisms that bind phenolics to proteins.     

核桃青皮中胡桃醌对大肠杆菌的抗菌作用及机制

为研究胡桃醌对大肠杆菌的抗菌活性及其作用机理,用不同质量浓度胡桃醌处理大肠杆菌,分别对最小抑菌质量浓度（minimal inhibitory concentration,MIC）、生长曲线、细胞膜相对电导率、荧光发射光谱等进行测定,并进行生物膜形成和细胞活性分析、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（sodium dodecyl sulphate-polyacrylamide gel electrophoresis,SDS-PAGE）以及大肠杆菌基因组合成分析。结果表明,胡桃醌对大肠杆菌具有有效的抗菌活性,MIC为0.062 5 mg/mL。经不同质量浓度胡桃醌处理后大肠杆菌细胞膜相对电导率升高,表明胡桃醌破坏了大肠杆菌膜的完整性,增加了细胞膜的通透性。荧光发射光谱分析结果表明,胡桃醌能够与膜蛋白相互作用从而改变大肠杆菌细胞膜结构。结晶紫和刃天青染色实验结果表明胡桃醌能够通过抑制大肠杆菌生物膜的形成减弱大肠杆菌的呼吸作用,进而抑制其活性。SDS-PAGE和大肠杆菌基因组合成分析结果显示胡桃醌可抑制大肠杆菌中蛋白质、DNA和RNA的表达。通过分子对接实验可知,胡桃醌可以结合到基因组DNA的...     

Properties of peroxidase and polyphenol oxidase in natural complexes from walnuts (Juglans regia) and in active DL-DOPA copolymers

Black polymers were extracted from walnut husk homogenates (Juglans regia L) in a phosphate buffer (pH 8.0) after air-bubbling for 24 h. After several purification stages, ultrafiltration and gel chromatography (Sephadex and Ultrogel), three extracts (two soluble and one insoluble) were isolated. At the same time, a synthetic DL DOPA/POD/PPO copolymer was prepared. Two walnut extracts exhibited POD and PPO activity. Both DL DOPA/POD/PPO copolymers (soluble and insoluble) only presented a POD activity. The insoluble and more complex extracts (either natural or synthetic) presented the lowest oxidase activities. The soluble walnut extract exhibited low though not negligible PPO and POD activities. It was observed using electrophoresis and gel chromatography that both enzymes were present in phenolic complexes. The high level of adsorption observed on polyacrylamide gel, as well as the elementary composition of these complexes enabled a comparison with phytomelanins. PPO and POD in the soluble copolymers (from both natural and synthetic sources) were governed by Michaelis-Menten kinetics. Apparent constants were calculated using the Lineweaver-Burk method. The use of limited proteolysis and an inhibitor showed good resistance of POD activity in walnut and synthetic copolymers and exceptional resistance of PPO activity in walnut extracts (particularly insoluble extract).     

核桃青皮活性成分的亚临界水提取工艺优化及抗氧化活性

该研究采用随机质心映射法优化了核桃青皮中的单宁酸、总黄酮及蒽醌等活性成分的亚临界水提取工艺,并考察了其抗氧化活性。结果表明,核桃青皮的最佳提取工艺为萃取温度194 ℃,萃取时间55 min,粉碎粒度80目。在此条件下,核桃青皮中活性成分总提取率为（147.59±0.59） mg/g,其中,总黄酮、单宁酸、蒽醌的提取率分别为（87.43±0.64） mg/g、（56.03±0.06） mg/g、（4.12±0.01） mg/g。在提取物质量浓度为0.6 mg/mL时对DPPH自由基清除率可达99.76%,质量浓度为0.8 mg/mL时对羟基自由基清除率可达97.42%。核桃青皮提取物对DPPH和羟基自由基清除作用的IC50分别为0.186 mg/mL和0.129 mg/mL。研究表明核桃青皮提取物具有较好的抗氧化活性。     

Antimicrobial activity of essential oil extracts of various onions (Allium cepa) and garlic (Allium sativum)

Antimicrobial activity of different concentrations (50, 100, 200, 300 and 500 ml/l) of essential oil extracts of three type of onions (green, yellow and red) and garlic against two bacteria, Staphylococcus aureus, Salmomella Enteritidis, and three fungi, Aspergillus niger, Penicillium cyclopium and Fusarium oxysporum, was investigated. The essential oil (EO) extracts of these Allium plants (garlic and onions) exhibited marked antibacterial activity, with garlic showing the highest inhibition and green onion the lowest. Comparatively, 50 and 100 ml/l concentrations of onions extracts were less inhibitory than 200, 300 and 500 ml/l concentrations. However, with garlic extract, high inhibitory activity was observed for all tested concentrations. S. aureus showed less sensitivity towards EO extracts inhibition, however S. Enteritidis was strongly inhibited by red onion and garlic extracts. The fungus F. oxysporum showed the lowest sensitivity towards EO extracts, whereas A. niger and P. cyclopium were significantly inhibited particularly at low concentrations. Conclusively, where seasoning is desired, essential oil extracts of onions and garlic can be used as natural antimicrobial additives for incorporating in various food products.