苦瓜茎皂苷的提取及降糖活性研究

研究苦瓜茎皂苷类物质的提取纯化工艺及降糖功效.在浸提温度为70℃,浸提时间3h,浸提溶剂为60％乙醇溶液,料液比1∶15的条件下对过60目筛的苦瓜茎粉浸提两次,粗提物经两次AB -8大孔吸附树脂纯化后得苦瓜茎皂苷,行HPLC分析并采用比色法检测提取物中皂苷的含量.采用苦瓜茎皂苷对高血糖小鼠及损伤的胰岛瘤细胞RIN - M5F细胞模型进行干预,观察高血糖小鼠血糖、胰岛素、肝糖原、SOD活性、MDA含量的变化,及损伤的RIN - M5F细胞的修复情况.结果表明,提取纯化后的苦瓜茎皂苷含量达到83％,与人参皂苷Rgl极性接近;经苦瓜茎皂苷灌胃后的高血糖小鼠血糖降低,血清胰岛素含量增高,肝糖原增加,丙二醛(MDA)含量降低;对损伤的RIN - M5F细胞有修复作用.     

等配比苦瓜多糖与皂苷调理高血糖的联合作用研究

通过研究苦瓜多糖及皂苷对高血糖联合调理的联合作用及机制,为苦瓜提取物的配方产品开发提供依据.腹腔注射链脲佐菌素(STZ)制作高血糖模型小鼠,苦瓜多糖及皂苷分别单独及联合给予高血糖模型小鼠,给药3周后,观察小鼠空腹血糖,血清胰岛素,糖原代谢,抗氧化能力及氧化应激能力的变化.与高血糖租(DM组)比较,联合组(配比1:1)小鼠血糖降低,血清胰岛素含量增高,肝糖原增加,乳酸脱氢酶(LDH)及乳酸(LD)降低;丙二醛(MDA)含量降低(P<0.05);联合组肝糖原(12.24±0.57)mg/g显著高于多糖组及皂苷组.等配比苦瓜多糖和皂苷联合使用可以通过增加糖原贮存,改善胰腺组织供氧及抗氧化能力等途径降血糖,多糖和皂苷改善糖原贮存的联合作用显著高于单独作用,具有一定的协同作用.     

苦瓜多糖与皂苷对高血糖协同预防作用机制研究

研究苦瓜多糖及皂苷对高血糖的协同预防作用,为预防高血糖的苦瓜复方保健食品的开发提供依据.用苦瓜多糖及皂苷灌胃3周,腹腔注射链脲佐菌素(STZ)诱导小鼠高血糖,观察小鼠的体重,肝肾脏器系数,血糖,胰岛素,糖原代谢,糖酵解,抗氧化能力的变化.结果表明,STZ注射前,各组小鼠血糖无差异(P＞0.05);STZ注射后,与对照组比较,协同组小鼠肝系数增高,血糖降低,胰岛素增高,肝超氧化物歧化酶(SOD)及乳酸脱氢酶(LDH)活性增强,丙二醛(MDA)含量降低,肌糖原增加(P＜0.05);协同组胰岛素为(17.74±1.19)μIU/mL, SOD为(366.43±28.28)U/mg·prot,显著高于多糖组及皂苷组(P＜0.05),血清LDH活性为(1 039.77±98.44) U/L, 显著低于多糖组及皂苷组.说明苦瓜多糖及皂苷能通过协同增加糖贮存、协同增强抗氧化能力及组织供养能力保护胰岛分泌功能等途径预防高血糖.     

苦瓜伤流液对链脲佐菌素诱导糖尿病小鼠的降糖功能研究

研究苦瓜伤流液(Momordica charantia L. Bleeding Sap,MBS)对链脲佐菌素(STZ)诱导糖尿病小鼠的降血糖功能并探索其作用机理。选用ICR 小鼠60 只,随机抽取10 只作空白对照,余下50 只禁食17～18h 后腹腔注射STZ170mg/(kg bw·d)。取血糖值在11.1mmol/L 以上者随机分组,共3 组：模型组、二甲双胍组(200mg/(kg bw·d))和 MBS 组(200mg/(kg bw·d))。连续灌胃30d 后,测定小鼠空腹血糖、血清胰岛素、血脂水平及肝糖原含量。解剖取胰腺,采用石蜡包埋、HE 染色,做组织切片观察。结果显示：苦瓜伤流液能显著降低糖尿病小鼠的空腹血糖值及血脂水平,增加血清胰岛素和肝糖原含量;胰腺切片提示,苦瓜伤流液能够改善胰岛组织功能,促进胰岛β细胞修复。结果表明苦瓜伤流液能促进糖尿病小鼠受损胰岛β细胞修复、刺激胰岛素分泌、增加肝糖原合成、调节血脂代谢,从而起到降低血糖的作用。     

苦瓜茎、叶中皂苷类物质的提取及分离纯化

苦瓜茎、叶中含有丰富的皂苷类物质.在浸提温度为70℃,浸提时间3h,浸提溶剂为60%乙醇溶液,料液比1:15,对60目的原料浸提两次,测得苦瓜茎、叶总皂苷的含量分别为2.92%和6.90%,提取率分别为5.9%和13.6%.粗提物中总皂苷的含量分别为49.5%和50.1%.粗提物经两次AB-8大孔吸附树脂分离纯化后,苦瓜茎、叶提取物中皂苷纯度分别达到83.4%和86%,经HPLC分析,主要有2种皂苷成分.     

苦瓜皂甙降糖机理研究

本研究从苦瓜皂甙对α-葡萄糖苷酶的活性影响,口服耐糖量试验,苦瓜皂甙对小鼠肝糖原和胰岛素水平影响这几个方面研究了苦瓜皂甙的净血糖机理.结果表明,苦瓜皂甙对α-葡萄糖苷酶没有抑制作用,葡萄糖耐量试验表明苦瓜皂甙能够使葡萄糖表现为正常耐受量,苦瓜皂甙还能使小鼠的肝糖原升高,但对小鼠的胰岛素水平没影响,这些结果表明:苦瓜皂甙不是通过抑制α-葡萄糖苷酶的活性来降低血糖,苦瓜皂甙能够使受损的胰岛β细胞恢复正常的分泌功能.苦瓜皂甙可能是通过刺激肝糖原合成来降低血糖作用.     

浙江七叶和汕美2号南瓜降血糖作用研究

研究并比较浙江七叶和汕美2号南瓜栽培品种对四氧嘧啶糖尿病小鼠降血糖作用。采用尾静脉注射四氧嘧啶建立小鼠糖尿病模型,灌胃南瓜提取物治疗7 d后测定小鼠空腹血糖和餐后血糖值、肝糖原、胰岛素、TG、TC、MDA含量和SOD活力水平。两种南瓜均对糖尿病小鼠有一定治疗效果,各提取部位均能显著降低糖尿病小鼠空腹血糖值和MDA含量,同时显著升高肝糖元、胰岛素含量及SOD活力水平,但对餐后血糖值影响不显著。且对各指标的影响,浙江七叶南瓜和汕美2号南瓜各部位提取物表现不同,浙江七叶南瓜提取物对糖尿病小鼠空腹血糖、肝糖原、SOD、MDA等指标的改善作用强于汕美2号南瓜提取物,而对TG与胰岛素含量的影响作用则相反。结果表明,南瓜治疗糖尿病的作用机制很可能是通过修复受损的胰岛β细胞使其恢复正常的分泌功能或是促进肝糖元合成及糖类转化有关,且与调节小鼠体内氧化应激作用有紧密的联系。     

苦瓜总皂苷降血糖及抗氧化作用的研究

目的:探讨了苦瓜总皂苷对小鼠的降血糖及抗氧化作用。方法:按30、60、120mg/kgbw给小鼠连续灌喂30d,测空腹血糖值、血清中超氧化物歧化酶活力、血清中丙二醛(MDA)含量。结果:苦瓜总皂苷对高血糖模型小鼠具有明显降低血糖作用和抗氧化能力的恢复作用,且高剂量组降血糖作用和恢复抗氧化能力的效果较好。     

苦瓜碱提多糖降小鼠血糖功能的实验研究

为研究苦瓜碱提多糖的降血糖功能,并分析它的降糖机理,分别对正常小白鼠和STZ诱导的糖尿病模型小鼠的降糖效果进行了比较,并对降糖机理进行初步分析.结果表明苦瓜碱提多糖400mg/kg的剂量可以显著降低正常小鼠和STZ糖尿病小鼠的血糖值,果糖胺的含量同样也有所降低.同时,苦瓜碱提多糖还可以提高糖尿病模型小鼠的葡萄糖耐量以及肝糖原的含量.苦瓜多糖的降糖机理可能是通过减弱STZ对胰岛β-细胞的损伤或改善受损β-细胞的功能,从而起到调节血糖的作用.     

2个品种南瓜有机溶剂提取物和多糖成分降血糖作用研究

目的:研究并比较十姐妹和改良蜜本南瓜栽培品种对四氧嘧啶糖尿病小鼠降血糖作用。方法:尾静脉注射四氧嘧啶建立小鼠糖尿病模型,灌胃南瓜提取物治疗7 d后测定小鼠空腹血糖和餐后血糖值、肝糖原含量、脂质过氧化物MDA含量和SOD活力水平。结果:2种南瓜提取物均对糖尿病小鼠均有一定治疗效果,各提取部位均能显著降低糖尿病小鼠空腹血糖值和MDA含量,同时显著升高SOD活力水平,但对餐后血糖值和肝糖原影响不显著。且对各指标的影响,十姐妹南瓜和改良蜜本南瓜表现不同,但其作用都优于改良蜜本南瓜多糖。结论:南瓜治疗糖尿病的作用机制很可能是通过修复受损的胰岛β细胞,使其恢复正常的分泌功能或是通过改善机体对胰岛素敏感性,增强葡萄糖利用率达到降糖目的,且与调节小鼠体内氧化应激作用有紧密的联系。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.