超声波辅助乙醇-硫酸铵双水相体系提取绞股蓝总黄酮工艺研究

本文采用超声波辅助乙醇-硫酸铵双水相体系提取绞股蓝总黄酮,并优化其工艺条件。在单因素试验的基础上结合正交试验,以总黄酮提取量为指标,探讨料液比、乙醇浓度、硫酸铵用量、超声功率和超声温度对绞股蓝总黄酮提取量的影响。结果表明：超声辅助乙醇-硫酸铵双水相提取绞股蓝总黄酮的最优工艺为：料液比1:30 （g/mL）,乙醇浓度50%,硫酸铵用量0.25 g/mL,超声功率240 W,超声时间40 min,超声温度70 ℃。在此条件下,总黄酮提取量为15.90 mg/g。超声波辅助乙醇-硫酸铵双水相提取绞股蓝总黄酮的效果较好,是提取绞股蓝中总黄酮的有效方法。 [关键词] 绞股蓝|总黄酮|超声波|乙醇-硫酸铵|双水相体系     

绿茄叶黄酮的响应面优化提取及其对酪氨酸酶的抑制作用

根据Box-Benhnken中心组合试验设计原理,在单因素试验的基础上采用三因素三水平的响应面分析法优化了绿茄叶黄酮的超声辅助硫酸铵的双水相提取工艺,并考察提取物对酪氨酸酶的抑制作用。结果表明,超声辅助乙醇-硫酸铵双水相体系提取绿茄叶黄酮的最优条件为:乙醇质量分数33%、硫酸铵质量分数20%、超声时间40 min、料液比1∶48(g/m L)。在最优工艺下,最大响应值(6.59%)和实验测定值(6.49%)基本符合,说明响应面法优化绿茄叶黄酮提取切实可行。同时,研究表明绿茄叶黄酮对蘑菇酪氨酸酶具有显著的抑制作用,抑制率随着绿茄叶黄酮质量分数的增大而增大,当质量分数为0.086 mg/m L时,绿茄叶黄酮对蘑菇酪氨酸酶的抑制率为45.7%。结果显示,绿茄叶含有大量的黄酮,并可有效抑制蘑菇酪氨酸酶的活性,具有潜在的开发利用价值。     

超声辅助双水相体系优化辛夷总黄酮提取工艺及其抗氧化活性研究

试验旨在优化超声辅助双水相法提取辛夷总黄酮的工艺条件,研究其体外抗氧化活性。以总黄酮得率为指标,采用单因素和响应面试验设计优化最佳提取条件,DPPH自由基清除率初步评价辛夷总黄酮的抗氧化活性。结果显示,超声辅助双水相法提取辛夷总黄酮最佳提取条件为聚乙二醇（PEG1000）质量分数40%、硫酸铵质量分数30%、液料比40 mL/g、提取时间30 min;此条件下对建立的数学模型进行试验验证,验证结果预测值为6.78%,实际值为6.81%,预测误差为0.79%。辛夷总黄酮对DPPH自由基清除率达77.36%,具有良好的抗氧化活性。研究表明,超声辅助双水相法操作简便,黄酮得率高,适用于辛夷总黄酮的提取。     

枇杷叶荚蒾叶片黄酮提取工艺研究

为了探讨不同因素对枇杷叶荚蒾叶片黄酮提取率的影响,试验采用单因素和正交试验方法对枇杷叶荚蒾叶片总黄酮的提取工艺进行研究。在单因素试验基础上选取固液比、乙醇浓度、提取温度和提取时间4个因素进行正交试验,并以总黄酮得率为考察指标。结果表明:影响枇杷叶荚蒾叶片黄酮提取的因素按主次顺序是固液比乙醇浓度提取温度提取时间。枇杷叶荚蒾叶片黄酮较优的工艺参数为:固液比1∶30,乙醇浓度60%,提取时间1.0 h,提取温度40℃,在此条件下黄酮提取率最大,为8.86%。     

蒲公英黄酮生物活性研究

优化蒲公英黄酮提取工艺,考察不同浓度蒲公英黄酮对羟自由基和DPPH(1,1-二苯基-2-三硝基苯肼)的清除能力。试验利用醇沉法超声提取蒲公英黄酮,采用正交试验的方法对超声波提取蒲公英活性成分的工艺进行优化,得到最佳的提取工艺,采用紫外分光光度计法测定黄酮提取物对羟自由基和DPPH自由基的清除效果。结果表明:提取蒲公英黄酮工艺的最佳提取条件为料液比1∶50(g/m L),乙醇质量分数50%,提取温度40℃,提取时间2.0 h,黄酮含量为6.84%。当黄酮质量浓度为1.2 mg/m L时蒲公英黄酮对羟自由基清除率最高,可达到54.35%;当黄酮质量浓度为1.4 mg/m L时蒲公英黄酮对DPPH自由基清除率最高,可达到94.59%。研究优化超声波提取蒲公英黄酮工艺,对蒲公英黄酮清除羟自由基和DPPH自由基效果进行研究。蒲公英黄酮对羟自由基和DPPH自由基清除效果均较好,为开发利用蒲公英资源提供理论依据,也为进一步开展蒲公英黄酮研究奠定理论基础。     

鬼针草总黄酮超声辅助提取工艺优化及抑菌活性研究

试验旨在优化鬼针草总黄酮超声辅助提取工艺,并对其抑菌作用进行研究,比较超声辅助提取法与传统提取方法的提取效率。试验采用正交设计对超声辅助提取法进行工艺优化;采用琼脂打孔法测定提取物的抑菌活性,采用微量倍比稀释法测定其最低抑菌浓度(MIC)和最小杀菌浓度(MBC)。结果显示:超声辅助回流提取法的提取得率高于其他方法。最佳提取工艺条件为:药材粉末加入10倍量50%乙醇,超声20 min,90℃下回流提取40 min,平均提取得率35.59%,提取物总黄酮平均含量5.54%。正交试验各组的提取物对金黄色葡萄球菌均有抑制作用。高黄酮组的MIC为15.62 g/L,MBC为125 g/L;低黄酮组的MIC为31.25 g/L,MBC为250 g/L。试验确定鬼针草总黄酮提取的最佳工艺和抑菌作用。     

大果木姜子黄酮的提取工艺优化及抗氧化活性研究

为研究大果木姜子黄酮的最佳提取工艺及其抗氧化效果,本试验以大果木姜子为研究对象,通过单因素试验分析了提取时间、超声功率、液料比、乙醇浓度和超声温度对大果木姜子黄酮含量和抗氧化活性的影响,在此基础上,采用总评归一-响应面法优化出的最佳提取条件进行验证。结果表明：大果木姜子黄酮最佳提取条件为液料比40：1（mL/g）,提取时间35 min,超声功率60 W,此条件下黄酮含量为2.48％,对DPPH自由基清除活性为93.18%。经总评归一-响应面优化得到的超声提取工艺稳定、可靠,可用于大果木姜子黄酮的提取,且具有较好的抗氧化活性。 [关键词] 大果木姜子|黄酮|响应面|抗氧化     

超声强化提取红菊苣黄酮及其抗氧化活性的研究

为了研究红菊苣黄酮的抗氧化活性,试验采用超声波辅助方法,以乙醇溶液为浸提液,采用L9(34)正交试验设计研究了红菊苣黄酮的最佳提取工艺,并测定了其对羟自由基(·OH)和1,1-二苯基-2-苦苯肼自由基(DPPH·)的清除效果。结果表明:黄酮最佳提取工艺条件为60%乙醇溶剂,超声功率200 W,超声提取时间20 min,料液比1∶25,在该条件下总提取率可达5.34%;红菊苣黄酮类化合物对·OH自由基和DPPH·自由基的清除率达到92.1%和93.4%。     

白术中黄酮的提取及其抑菌和抗氧化活性的研究

为了研究白术中黄酮的抑菌与抗氧化活性,为白术资源的深度开发利用提供依据,试验以总黄酮提取率为评价指标,采用正交试验优化了白术中黄酮的超声提取工艺,并采用最小抑菌浓度法和清除二苯代苦味肼基自由基(DPPH·)法测定了其抑菌和抗氧化活性。结果表明:白术黄酮超声提取的最佳工艺条件为,乙醇浓度为60%,料液比(g/m L)为1∶40,在50℃下超声提取35 min,在该条件下黄酮的提取率为1.38%;白术黄酮对金黄色葡萄球菌、大肠杆菌和枯草芽孢杆菌均有较强的抑菌活性,而对酵母菌和产青霉菌则没有抑制作用;白术黄酮及维生素C对DPPH·的半清除率(IC50)分别为17.26μg/m L、12.68μg/m L,说明白术黄酮具有较强的抗氧化活性。     

响应面法优化桑叶黄酮的提取工艺及提取物抗氧化性能的研究

为了给桑叶黄酮作为天然抗氧化剂开发提供参考依据,试验以桑叶为研究对象,通过单因素试验分析了超声波辅助、提取时间、提取温度、料液比以及乙醇浓度对桑叶黄酮提取率的影响,利用响应面法优化了桑叶黄酮提取工艺,并结合1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除试验评估了提取物的抗氧化性能。结果表明:超声波辅助能够显著提高桑叶黄酮提取率(P0.05);响应面模型得到的提取条件为乙醇浓度54.75%、提取时间17.61 min、料液比1:30.24(g/m L)、温度50.27℃,此时桑叶黄酮提取率最高为3.64%;实际测得提取时间17 min、提取温度50℃、料液比1:30(g/m L)、乙醇浓度55%的条件下桑叶黄酮提取率为3.62%,与理论值相对偏差为0.55%,且该条件下提取物DPPH自由基清除活性为99.12%。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Evaluation of the Microbiological Status of Milk and Various Structures in Mammary Glands from Naturally Infected Dairy Cows

A knowledge of the microbiological status of milk and of the different structures in the mammary glands has great importance in elucidating the pathogenesis of mammary gland infections. The objective of this study was to evaluate the microbiological status of various structures in the mammary glands from naturally infected dairy cows following slaughter. A total of 94 samples of milk, 184 samples of mammary parenchyma, 168 samples of gland cisterns, and 168 samples of teat cisterns were collected for microbiological examination. Microorganisms were detected in 59.9% of all samples, 67.0% of the milk samples, 70.1% of the mammary parenchymas, 55.9% of the gland cisterns and 48.8% of the teat cistern samples. When all samples were considered, coagulase-negative Staphylococcus were the most prevalent (35.7%) followed by coagulase-positive Staphylococcus (12.2%), Corynebacterium bovis (2.4%), Prototheca sp. (1.9%), and Streptococcus dysgalactiae (1.5%). There was a significantly higher occurrence of microorganisms in the milk and mammary parenchyma compared to the gland cisterns and teat cisterns. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development and survival of free-living stages of gastrointestinal nematodes of sheep and goats on pasture in the Nigerian derived savanna

Four grass plots were sequentially contaminated with goat faeces containing known numbers of unembryonated eggs of predominantly Haemonchus contortus and Trichostrongylus spp. between October 1982 and April 1983. Four other plots were similarly contaminated with sheep faeces between February and May 1987. An additional plot was repeatedly contaminated with sheep faeces from February to April 1987. Populations of free-living stages in faeces and of infective larvae (L₃) in the herbage were subsequently monitored until the end of April and June of 1983 and 1987 respectively. During February and May 1987 two control cultures of sheep faeces were incubated in the laboratory at 25°C–30°C and at a constant temperature of 50°C and the free-living development was also monitored. L₃ developed very readily in the faeces cultured at 25°C–30°C and in those spread on a grass plot in October, at the end of the wet season, but developed less on the plot contaminated in May at the start of the wet season. Worm eggs in faeces deposited on plots during the hot dry season (December to April) or incubated at 50°C died and disintegrated after 24–48 h exposure to the high environmental temperatures. The results indicate that it is unlikely that gastrointestinal nematodes of sheep and goats can develop or survive on open pasture during the dry season in the Nigerian derived savanna zone.