核桃青皮主要成分胡桃醌的生物活性研究进展

核桃青皮含有多种生物活性成分,其中一种主要的生物活性成分为胡桃醌,具有止血,抑菌消炎、抗肿瘤、镇痛、抗氧化、抑癌等药理活性,广泛应用于食品,医疗,染料等多个领域.该文对胡桃醌的生物活性研究进展进行综述,为胡桃醌未来的开发利用提供参考.     

山核桃外果皮中胡桃醌含量测定及抑菌活性

对山核桃外果皮中胡桃醌的含量进行测定,并对其抑菌活性进行了研究.HPLC测定山核桃外果皮中胡桃醌含量为0.001 04%(干样).胡桃醌对供试的9种病原真菌菌丝生长抑制的EC50值为水稻纹枯病菌7.0226 mg/L,苹果腐烂病菌13.145 6 mg/L,水稻稻瘟病菌299.0976 mg/L.胡桃醌对苹果炭疽病菌孢子萌发抑制EC50值为0.5083 mg/L,对玉米大斑病菌EC50值为2.236 mg/L.活体测定中,胡桃醌1000 mg/L对番茄灰霉病菌保护作用率为42.52%,胡桃醌750 mg/L对番茄灰霉病菌治疗作用率为20.92%,与对照药剂丙烷脒相当.     

核桃青皮中多糖的现状分析

多糖广泛分布于自然界中,目前核桃青皮中多糖的研究较少,本文主要介绍多糖的提取方法及应用领域。     

核桃枝多酚含量测定及体外抗氧化活性研究

以核桃枝粉末为原料,利用1,1-二苯基-2-三硝基苯肼(DPPH)、羟自由基(·OH)法研究核桃枝多酚体外的抗氧化活性.测得核桃枝多酚对DPPH自由基的清除率是96.85％;对·OH的清除比率是49.35％.结果表明:核桃枝多酚在体外具有一定的抗氧化活性,快速灵敏的体外实验初步分析筛选出了新的抗氧化物质来源,为核桃枝的...     

利用核桃青皮制作油田化学品的试验研究

本实验通过核桃青皮粉末处理水基钻井液,讨论温度、果皮加量对水基钻井液性能的影响;同时加热使果皮粉末部分溶解,测试对膨润土膨胀的抑制性能。为进一步探讨果皮在改善钻井液的滤失、粘度性能方面的作用,对果皮做了配伍性实验。     

黄芩的抗菌活性及HPLC分析

将黄芩用V(乙醇)∶V(水)=70∶30进行提取,提取物(SC)按极性大小分成四个部位:正己烷(SC1),乙酸乙酯(SC2),正丁醇(SC3),水部位(SC4),用打孔法测定每个部位的抑菌圈,用试管稀释法测定SC2,SC3和SC4对大肠杆菌和枯草杆菌的最低抑菌质量浓度(M IC)分别为2,>2,>2 g/mL;1,2,>2 mg/mL。HPLC对总提物及各个部位的主要成分进行了定性分析,结果表明,SC的主要成分为黄芩素、汉黄芩素和黄芩苷;SC2的主要成分为黄芩素和汉黄芩素;SC3主要成分为黄芩素和黄芩苷;SC4的主要成分为黄芩苷。     

核桃青皮化学成分及其缓蚀作用研究进展

以核桃青皮为研究对象,概述了其化学成分和对金属缓蚀性能的研究进展,并从提取方法、溶液介质选择、实验方法、原料质量等方面进行了展望,为该类缓蚀剂的进一步研究提供方向和目标.     

核桃青皮中蒽醌类色素提取及稳定性

在确定了核桃青皮中蒽醌类色素含量分析方法的基础上,采用L9(34)正交实验研究了乙醇提取核桃青皮中蒽醌类色素的最佳提取工艺;考察了光照、氧化还原剂、金属离子对核桃青皮提取液中蒽醌类色素稳定性的影响。结果表明,比色法测定核桃青皮中的蒽醌类色素的精密度高,稳定性和重复性好,平均回收率为103.29%,相对标准偏差(RSD)为1.57%,线性范围为0.004 16~0.025 0 g/L(R=0.999 7);当料液比为1∶30(g∶mL)、超声时间为30 min、温度为60℃、乙醇体积分数为50%时核桃青皮色素的提取率最高。对核桃青皮提取液的色素稳定性研究表明,核桃青皮蒽醌类色素具有较好的耐光性和耐还原性,金属离子K+、Na+、Mg2+、Ca2+、Zn2+对其稳定性影响不大,但Fe3+有明显的增色效果。     

核桃青皮中蒽醌类色素提取及其稳定性研究

在确定了核桃青皮中蒽醌类色素含量分析方法的基础上,采用L9(34)正交实验研究了乙醇提取核桃青皮中蒽醌类色素的最佳提取工艺;考察了光照、氧化还原剂、金属离子对核桃青皮提取液中蒽醌类色素稳定性的影响。结果表明,比色法测定核桃青皮中的蒽醌类色素的精密度高,稳定性和重复性好,平均回收率为103.29%,相对标准偏差(RSD)为1.57%,线性范围为0.004 16~0.025 0 g/L(R=0.999 7);当料液比为1∶30(g∶mL)、超声时间为30 min、温度为60℃、乙醇体积分数为50%时核桃青皮色素的提取率最高。对核桃青皮提取液的色素稳定性研究表明,核桃青皮蒽醌类色素具有较好的耐光性和耐还原性,金属离子K+、Na+、Mg2+、Ca2+、Zn2+对其稳定性影响不大,但Fe3+有明显的增色效果。     

维药核桃青皮的生药学研究

对核桃青皮的性状、显微特征进行了鉴别,采用薄层色谱(TLC)法对核桃青皮中齐墩果酸进行了定性鉴别;采用单因素实验优化了核桃青皮中齐墩果酸的提取工艺,并采用紫外可见分光光度法测定了核桃青皮中齐墩果酸的含量。结果表明,以三氯甲烷-甲醇-甲酸(21∶0.15∶0.5,体积比)为展开剂时,核桃青皮中齐墩果酸的TLC图谱斑点清晰,分离度好;核桃青皮中齐墩果酸的最佳提取工艺为：超声提取、以甲醇为提取溶剂、超声时间40 min;齐墩果酸浓度在0.007 28～0.072 80 mg·mL^-1范围内与吸光度呈良好的线性关系;5批新疆不同产地的核桃青皮中齐墩果酸平均含量为1.988 mg·g^-1。该方法操作简便、结果准确,适用于核桃青皮的质量控制。     

采出水配伍性及结垢趋势评价方法与展望

综述了国内外油田水配伍性实验原理及评价方法,包括静态配伍性实验和动态配伍性实验,并对比评价了各种方法在工程实际应用中的优缺点。同时描述了垢的形成机理并提出了几种不配伍性导致的结垢趋势评价方法,分别是静态模拟实验法、动态模拟实验法、计算机预测法。最后展望了结垢趋势预测的最佳方式,需全面考虑热力学、流体力学以及结晶动力学等因素,注重水的结垢速率研究,从而开发更通用更准确的结垢预测模型是今后发展的方向。     

Comparison between conventional and ultrasound-assisted extractions of natural antioxidants from walnut green husk

Agricultural industries produce substantial quantities of phenolic-rich by-products, which have gained much attention due to their antioxidant properties. Ultrasonic technology was applied for extraction of antioxidants from the walnut green husk using ethanol as a food grade solvent. Response surface methodology (RSM) was used to optimize experimental conditions. The responses were total phenolic content (TPC), ferric reducing antioxidant power (FRAP), scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and yield. TPC varied from 6.28 to 7.23mg GA g^?1 dry sample. FRAP and DPPH values varied from 0.33 to 0.46 mmol Fe²⁺ g^?1 of dry sample and 33.98% to 56.31% inhibition, respectively. Extraction yields ranged from 33.04% to 38.72%. The optimal conditions were 60% ethanolwater mixture as solvent, temperature of 60 °C and extraction time of 30 min. Comparison of ultrasonic-assisted extraction (UAE) and conventional extraction was shown that TPC, FRAP, DPPH and yield obtained by UAE during 30 min were significantly higher than by conventional extraction during 16 hours. The extract can be used as substitute of synthetic antioxidants for food products, color and oxidative stabilization.     

Evaluation of antimicrobial and dyeing properties of walnut (Juglans regia L.) green husk extract for cosmetics

Walnut green husk is one of the main waste products from walnut and could be used as a source of natural dyeing compounds such as juglone. The present study was conducted to evaluate the effective use of walnut green husk extract as a natural hair dye. Dyeing properties, fastness and antimicrobial behaviours of dyed hair and also a skin irritation test for natural hair dye on rat skin were examined. When the extract was mixed with ascorbic acid as a developer, ferrous sulphate as a mordant, and Aloe vera extract used as a secondary mordant and also a cosmetic ingredient, the reaction resulted in a dark‐brown colour on hair samples. The dyed hair exhibited appropriate colour strength having excellent morphology for a hair surface coated with dye molecules. In addition, the dyed hair possessed good resistance to washing and daylight fastness, without any irritant properties as shown in a rat model, although high concentrations of iron‐based mordant may be problematic for long‐term usage. This paper also suggests the use of natural mordants such as lactic and oxalic acids to avoid any probable risks. Walnut green husk extract was an appropriate natural hair dyeing agent in practice and showed maximum antimicrobial activity compared with semi‐synthetic and commercial hair dyes. The results demonstrated that walnut green husk can be used as an economical, valuable, eco‐friendly and safe source of dyeing and antimicrobial agents for cosmetic products.     

Seasonal changes of juglone potential in leaves of black walnut (Juglans nigra L.)

The literature concerning the extraction and quantification of juglone (5-hydroxy-1,4-naphthoquinone) frequently fails to differentiate between juglone and its immediate precursors. The proposal that the term “juglone potential” be used to define the total concentration of juglone under an oxidative environment in walnut tissues is made. The juglone potential of a given tissue will more accurately reflect the allelopathic agent's presence than will juglone concentration of the tissue alone. The term juglone potential accepts the multiple chemical nature of juglone found in walnut tissue and gives a precise way for quantification of allelopathic action. The objective of this study was to measure seasonal changes in black walnut juglone potentials at various locations in the crown. Juglone potentials were measured weekly in leaves at the top, middle, and bottom of the tree crowns. The results showed a linear decrease in juglone potential over the growing season. The results also showed no significant difference in leaf juglone potentials among the three crown positions. If reanalyzed without the middle crown position juglone potentials were significantly greater in the lower crown positions when compared with the higher crown position. Potential use of juglone to manipulate species composition and decrease interference in plant communities is discussed.     

果皮果壳膳食纤维含量及性能测定

以香蕉皮、橘子皮、花生壳、荔枝皮为原料,分别采用热水浸提法和酸碱法制备水溶性膳食纤维和水不溶性膳食纤维,并且测定了后者的持水性和溶胀性。提取水溶性膳食纤维最佳实验条件是p H=7、提取温度为100℃、料液比为1:20、提取时间30min,花生壳水溶性膳食纤维产率最高,达到3.43%。橘子皮提取的水不溶性膳食纤维产率(38.23%)、持水性(4.35g/g)和溶胀性(1.12ml/g)均适中,是比较理想的原料。     

Seasonal patterns of juglone in soil beneathJuglans nigra (black walnut) and influence ofJ. nigra on understory vegetation

The allelopathic nature ofJ. nigra L. was investigated in several planted mixed hardwood stands located near Syracuse, New York. Concentrations of chloroform-extracted juglone from soil collected beneathJ. nigra was determined by thin-layer chromatography (TLC) and high-pressure liquid chromatography (HPLC). Soil juglone concentrations were corrected based on recovery of synthetic juglone added to soil. Soil juglone levels were high in the spring, decreased during the summer, and were high again in the fall. The quantification of juglone from soil by HPLC was found to be more accurate than by TLC. Regression analysis indicated that individual tree variation in soil juglone levels could not be explained by differences in soil moisture, pH, organic matter content, and texture. The results of juglone recovery experiments suggest that chloroform-extractable juglone does not persist in soil. Juglone degradation by microorganisms could only explain a portion of the juglone decline. Ordinations revealed that the herbaceous and woody vegetation beneathJ. nigra, in comparison to vegetation beneathAcer saccharum andQuercus rubra, is distinct in only one of the four stands studied. This vegetational difference did not appear to be a consequence of any strong allelopathic influences ofJ. nigra (Scheffe's method of contrast, chi-square analysis). The allelopathic nature of juglone under these field conditions is questionable.     

The antifungal activity and biotransformation of diisophorone by the fungus Aspergillus niger

The microbial transformation of racemic diisophorone was investigated using the plant pathogen Aspergillus niger as a biocatalyst. Incubation of diisophorone with Aspergillus niger gave 8α‐hydroxy‐diisophorone, 10‐hydroxydiisophorone and 17‐hydroxydiisophorone on the basis of their spectroscopic data including two‐dimensional NMR analysis, nOe and an X‐ray crystallographic study. The antifungal activity of diisophorone against Aspergillus niger was also examined. Copyright © 2004 Society of Chemical Industry     

Comparative study of the influence of active groups of chitosan derivatives on antifungal activity

In this study, series of chitosan derivatives containing active groups were synthesized and evaluated for their antifungal activity against three crop‐threatening fungi, Fusarium oxysporum. f. sp. Vasinfectum, Alternaria solani, and Valsa mali. Schiff bases of carboxymethyl chitosan (As: 2‐(2‐hydroxy‐5‐nitrobenzylideneamino)‐6‐carboxymethyl chitosan; Bs: 2‐(2‐hydroxyl‐5‐chlorobenzaldimino)‐6‐carboxymethyl chitosan), N‐substituted carboxymethyl chitosan (An: 2‐(2‐hydroxyl‐5‐nitrobenzylamino)‐6‐carboxymethyl chitosan; Bn: 2‐(2‐hydroxyl‐5‐chlorobenzylamino)‐6‐carboxymethyl chitosan) and 2‐urea‐carboxymethyl chitosan (Au: 2‐(2‐nitrophenylurea)‐6‐carboxymethyl chitosan; Bu: 2‐(2‐chlorophenylurea)‐6‐carboxymethyl chitosan) were synthesized, and their antifungal activity was comparatively studied by hypha measurement in vitro, respectively. Results obtained from this study revealed that the active groups combined with Schiff bases functional groups (C?N) could strengthen the antifungal activity most effectively among the compounds studied in this work. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Determination of filler content in rice husk ash and wood-based composites by thermogravimetric analysis

Three new types of fillers for polypropylene are investigated. The first two were derived from burnt rice husk ash (RHA), whereas the third, a wood-based filler, was processed from oil palm trunk. One important characterization of the composites involves the checking for the actual filler content and filler distribution within the matrix. An analytical technique is described here for computation of the filler content in the composites based on a simple expression derives from thermogravimetric analyses. For filler with volatiles such as the black RHA, the derived expression was p _f = 106 ( r _b / m _c ), and for easily burnt fillers (wood-based), the expression was p _f = 156 ( m _d / m _c ). The technique has shown good agreement and consistency between analyzed and actual filler contents and a uniform filler distribution within the polypropylene matrix. © 1994 John Wiley & Sons, Inc.