顶羽菊抗氧化活性研究

目的:探讨顶羽菊提取物的抗氧化活性。方法:采用Folin-Ciocaheu法测定顶羽菊水提物和醇提物中的多酚含量,并以芦丁为标准品测定其黄酮含量;通过总还原力测定法、Fenton法、改良的邻苯三酚自氧化法、过氧化脂质测定、亚硝酸盐清除率测定和亚硝胺合成阻断率测定,分别对顶羽菊提取物的总还原力、超氧阴离子自由基和羟自由基清除能力、脂质过氧化抑制作用、清除亚硝酸盐自由基和亚硝胺阻断率进行测定。结果:顶羽菊水提物和醇提物中含有以黄酮类为主要成分的多酚类物质;具有较强的还原性和清除超氧阴离子自由基、羟自由基的活性,且醇提物的作用高于水提物;二者对脂质过氧化的抑制率达47%以上;顶羽菊提取物具有较强的清除亚硝酸钠和阻断亚硝胺合成的能力,水提物对亚硝酸盐的最大清除率为60.4%,醇提物对亚硝胺合成的阻断率为86.6%。结论:顶羽菊醇提物可作为抗氧化剂和防癌剂,用于清除机体内自由基、抗脂质氧化、延缓机体衰老、预防心血管系统疾病和癌症的发生。     

响铃草总黄酮清除自由基及抑制亚硝化作用的研究

优选响铃草总黄酮的最佳提取工艺,并考察其清除自由基及对亚硝化反应的抑制能力。通过正交试验设计对乙醇提取响铃草总黄酮的工艺进行优化;采用紫外分光光度法测定响铃草总黄酮对自由基的清除作用和对亚硝酸钠的清除率以及对亚硝胺合成的阻断率。结果表明,最佳提取工艺条件为:乙醇浓度65%,料液比1∶30,提取温度75℃,提取时间3 h,在此最佳工艺条件下,黄酮得率为1.72%;响铃草总黄酮对羟自由基和超氧阴离子自由基有一定的清除作用;并且能够有效的清除亚硝酸钠和阻断亚硝胺的合成。     

毛豹皮樟叶水提物的活性成分及其清除亚硝酸钠和阻断亚硝胺合成的作用

亚硝酸盐在食材、食品加工和食品储存过程中普遍存在,它是亚硝基化合物合成的前体物质,在一定条件下亚硝酸盐极易转化为亚硝胺,二者均可致癌[1-2],因此,清除亚硝酸盐和阻断亚硝胺合成对于预防和控制癌症的发生具有重要意义。关于清除亚硝酸盐和阻断亚硝胺合成的研究已有较多报道,一些植物含有的天然活性成分,如植物中所含的多酚和黄酮类物质等,具有抗氧化、抗菌、清除亚硝酸盐和阻断亚硝胺合成的作用。顶羽菊也Acroptilon repens ( Linn.) DC.页[3]、黄花菜(Hemerocallis citrina Baroni)[4]和簕菜也Acanthopanax trifoliatus ( Linn.) Merr.页[5]等提取物具有清除亚硝酸盐和阻断亚硝胺合成的作用;黄俊生[6]从南姜也Alpinia galanga ( Linn.) Willd.页表皮中提取的色素也具有较强的清除亚硝酸钠和阻断亚硝胺合成活性。     

红冬蛇菰提取物抗氧化及抑制亚硝化作用研究

对红冬蛇菰不同溶剂提取物的抗氧化活性及抑制亚硝化作用进行比较研究。采用DPPH法、ABTS法和普鲁士蓝法分别测定各提取物的自由基清除能力和铁离子还原力,以评价红冬蛇菰的抗氧化能力;采用盐酸萘乙二胺法和α-萘胺法分别测定红冬蛇菰各提取物对亚硝酸盐的清除率和对亚硝胺合成的阻断率,以评价红冬蛇菰的抑制亚硝化作用。实验结果表明,红冬蛇菰各提取物中乙酸乙酯提取物清除DPPH自由基(IC_(50)=0.06±0.001 mg/mL)和ABTS自由基(IC_(50)=0.07±0.001 mg/mL)能力以及对铁离子还原能力最强,并显著强于其他提取物(P0.01),其中清除ABTS自由基的能力显著高于Vc(IC_(50)=0.10±0.002 mg/mL)(P0.01);在模拟人体胃液的条件下(pH 3.0,温度37℃),各提取物能有效地清除亚硝酸盐以及阻断亚硝胺合成,并随着反应质量浓度增加清除率和阻断率增大最后趋于平缓,其中乙酸乙酯提取物对亚硝酸盐的清除能力(IC_(50)=1.91±0.022 mg/mL)和亚硝胺合成的阻断能力(IC_(50)=8.44±0.091 mg/mL)均显著强于其他提取物(P0.01)。红冬蛇菰提取物属天然产物,具有较好的抗氧化活性和抑制亚硝化作用,因此在抗氧化剂的研究方面具有潜在的开发利用价值,同时极有可能是一种新的防癌抗癌天然保健品。     

化橘红黄酮类化合物抑制亚硝化反应活性研究

根据超声波最佳提取工艺条件提取得到化橘红总黄酮,经乙酸乙酯萃取分为酯溶性和水溶性两部分,比较它们对亚硝化反应的抑制作用,并分别采用硅胶柱层析对酯溶性成分分离纯化,采用大孔吸附树脂法对水溶性成分进行分离纯化,得到4个主要的黄酮类化合物,研究它们对亚硝化反应的抑制作用,以期得到抑制亚硝化活性较强的化合物。结果表明化橘红总黄酮提取率可达26.42%,酯溶性和水溶性部分均能阻断亚硝胺的合成及清除亚硝酸盐,其中水溶性黄酮提取物作用较强,分离得到的4个黄酮类化合物中柚皮苷的抑制作用较强,对亚硝胺的合成的最大阻断率可达94.7%,对亚硝酸盐的最大清除率可达92.3%。     

石韦提取物抗氧化及抑制亚硝化作用研究

研究石韦不同溶剂提取物的总酚、总黄酮含量和抗氧化及抑制亚硝化活性,并分析其相关性。采用福林酚比色法和硝酸铝络合分光光度法分别测定各提取物中总酚、总黄酮的含量,以DPPH法、ABTS法和普鲁士蓝法分别测定各提取物的自由基清除能力和铁离子还原力,采用盐酸萘乙二胺法和α-萘胺法分别测定石韦各提取物对亚硝酸盐的清除率和对亚硝胺合成的阻断率,采用Pearson法分析总酚、总黄酮含量与抗氧化及抑制亚硝化活性的相关性。结果表明:石韦不同溶剂提取物的总酚和总黄酮含量存在显著性差异,其中正丁醇提取物的总酚、总黄酮含量均最高,分别为29.85±2.15和37.23±2.41 mg/g。各提取物均具有较强的抗氧化和抑制亚硝化活性,以正丁醇提取物的效果最显著,其DPPH自由基清除能力(IC_(50)=44.14±1.21μg/mL)、ABTS自由基清除能力(IC_(50)=97.47±12.10μg/mL)和还原能力(822.08±24.82μmoL Vc/g),以及对亚硝酸盐的清除能力(IC_(50)=7.071±0.231 mg/mL)、对亚硝胺合成的阻断能力(IC_(50)=15.010±1.224 mg/mL)均最强,并显著强于其他提取物(P0.05)。相关性研究显示,石韦各提取物的抗氧化活性和抑制亚硝化活性与其总酚和总黄酮含量呈显著正相关(P0.05),表明总酚类和总黄酮类物质是石韦发挥作用的物质基础。通过对石韦不同提取物的总酚和总黄酮含量的测定、抗氧化和抑制亚硝化作用评价及相关性分析,为石韦的进一步开发利用提供实验数据和参考依据。     

原花青素对亚硝化反应的抑制作用研究

研究了葡萄籽原花青素的最佳提取条件,及其对亚硝化反应的抑制作用。结果表明：原花青素的最佳提取条件为60％乙醇,料液比1：5,50℃水浴回流1h,其对亚硝胺合成的最大阻断率为91．2％,对亚硝酸钠的最大清除率为88．3％。     

桑椹醇提物清除亚硝酸盐及阻断亚硝胺合成的研究

为系统评价桑椹醇提物对亚硝化反应的体外抑制活性,在体外不同桑椹品种、浓度和作用时间条件下,实验研究了桑椹醇提物对亚硝酸盐的清除和二乙基亚硝胺(NDEA)生成的影响及其相关功能成分含量。结果显示,不同品种的桑椹总酚、原花青素和总黄酮含量差异显著,PR-01黑果桑的原花青素含量(155.41 mg/g)和总黄酮含量(3.05 mg/g)最高;随浓度提高和作用时间延长,桑椹醇提物清除亚硝酸盐和阻断NDEA合成能力增强。15种桑椹醇提物对亚硝化反应均具有一定的抑制作用,以PR-01黑果桑的效果最显著,其最大清除率和阻断率分别达到92.40%和87.25%,与抗坏血酸效果相当;桑椹醇提物对亚硝酸盐的清除率和对NDEA合成的阻断率与其总酚、原花青素、总黄酮含量呈一定的相关性。综上:桑椹醇提物具有较好的清除亚硝酸盐和阻断NDEA合成的作用,原花青素、多酚类、黄酮类物质可能是其发挥作用的物质基础。     

樟芝发酵液和菌丝体提取物抗氧化性能研究

采用甲醇、乙醇、异丙醇对樟芝发酵液和菌丝体进行提取,对其不同提取物进行还原力,DPPH、羟基自由基、超氧自由基、过氧化氢清除能力,亚铁离子螯合能力等抗氧化能力的测定。比较发酵液提取物和菌丝体提取物的抗氧化效果,比较不同提取剂提取物的抗氧化效果。结果显示:(1)发酵液提取物还原力最高的为异丙醇提取物,亚铁离子螯合能力最强的为乙醇提取物;DPPH清除能力乙醇和异丙醇提取物最高都达到97.88%;羟基自由基清除能力最高的为乙醇提取物,达到84.22%;3种提取物的超氧自由基清除能力都较高,具有最高清除率的异丙醇提取物达到94.89%;过氧化氢清除能力最高的为乙醇提取物的97.53%。(2)菌丝体提取物还原力最高和亚铁离子螯合能力最强的均为乙醇提取物;DPPH清除能力最高的为乙醇提取物的89.95%;3种提取物的羟基自由基清除能力普遍偏低,最高的仅为异丙醇提取物的37.28%;超氧自由基清除能力则普遍较高,最高为甲醇提取物的90.05%;过氧化氢清除能力最高的为乙醇和异丙醇提取物,最高清除率均为95.06%。抗氧化性能的研究比较,为进一步开发利用樟芝提供了依据。     

槲皮素微乳对亚硝化反应的抑制活性研究

为提高槲皮素的水溶性,制备了O/W型吐温80-乙醇-花生油-水的微乳体系,考察了该体系对槲皮素的增溶效果,结果槲皮素的溶解度由4.8 μg/mL增加到319.1 μg/mL.在模拟人体胃液的条件下,测定槲皮素微乳对亚硝化反应的抑制活性.结果表明:槲皮素微乳对亚硝化反应具有较强的抑制作用,对亚硝胺合成的最大阻断率为89.28%,对亚硝酸钠的最大清除率为90.47%.     

7,8-Benzoflavone: a phytotoxin from root exudates of invasive Russian knapweed

Root exudates from Acroptilon repens (Russian knapweed) were found to be phytotoxic and the phytotoxin in the exudate was identified as 7,8-benzoflavone (alpha-naphthoflavone), (1), not previously known as a natural product. In tests on growing seedlings both 1 and its isomer 5,6-benzoflavone (2) were phytotoxic. Flavone, a structural analog of 1 and a known granular leaf and stem exudate of other plant species, was also phytotoxic and more potent than 1 or 2.     

铺地锦竹草水提取物主要成分及抗氧化活性研究

以市售铺地锦竹草为材料制备其水提取物,采用分光光度法测定总黄酮、总花色苷、总糖等主要活性成分含量,采用ICP-MS质谱仪法测定提取物中18种金属元素的组成和含量,最后采用分光光度法研究提取物的体外抗氧化活性。结果显示,铺地锦竹草提取物中黄酮含量为2.04%,总蛋白含量1.83%,总糖含量55%,总花色苷含量7.2%,Ca、Mn、Mg等有益微量元素含量较高,Pb、Hg、Ag、Co、Ge等有害重金属微量检出或未检出。提取物清除DPPH·的IC50达0.265mg·mL^-1,清除·OH自由基IC50为1.16mg·mL^-1,1mg提取物的总还原力与39μgVc相当,对亚铁离子未表现出有规律的螯合力。以上说明铺地锦竹草提取物中天然活性成分含量较高,有害重金属极微,具有良好的抗氧化能力,其抗氧化活性是由多种活性因子通过协同作用机制起作用的,具有开发为功能性食品的良好潜力。     

外来杂草加拿大一枝黄花对入侵地植物的化感效应

采用人工气候箱培养试验,初步研究了入侵杂草加拿大一枝黄花对本地植物的化感作用.测定了根系和根状茎的不同浓度浸提液对白三叶发芽率和幼苗生长的影响;不同播种密度下根系1:60提取浓度对白三叶种子萌发和幼苗生长的影响;根状茎1:60提取浓度对白三叶、红三叶、天蓝苜蓿、黑麦草、北美车前、鸡眼草、苇状羊茅、胜红蓟、马齿苋、碱蓬和刺苋的种子萌发和幼苗生长的影响.结果表明,加拿大一枝黄花根系和根状茎的化感抑制作用均随浓度的升高而增强,且根状茎提取物的抑制效应高于根系提取物的效应;在1:60低浓度根系浸提液作用下,不同密度的白三叶幼苗萌发率和幼根、幼芽长度差异不显著;1:60低浓度根状茎提取物对11个物种的种子萌发均有显著抑制作用,但对不同物种的抑制程度有差异,对禾本科植物的抑制作用大于非禾本科和豆科;1:60低浓度根状茎提取物对10个物种的幼根影响与对萌发率的影响相似,但在对幼芽的影响上,仅对鸡眼草、刺苋和苇状羊茅起抑制作用,而对其他植物无显著抑制(黑麦草、北美车前、胜红蓟、马齿苋和刺苋)或起促进作用(白三叶、红三叶、天蓝苜蓿).     

Post-invasion evolution of native plant populations: a test of biological resilience

Contemporary evolution may explain the success of some exotic plant invasions. However, the evolutionary response of recipient native plant populations to exotic invasion has received relatively little attention. Because plant populations are genetically variable, contemporary evolution may also occur in native populations following entry of invasive species. Previously, we documented molecular differences in native populations; here we extend these studies to evaluate growth of native species in a common garden experiment. We seek to determine if three populations of two native grass species ( Hesperostipa comata and Sporobolus airoides ) demonstrate evidence of contemporary evolution in response to invasion by Acroptilon repens . We obtained 50 genets of the two native grass species from communities long-invaded (25–80 years) by A. repens and from adjacent, noninvaded areas, and planted five transplants of each genet into two A. repens infestations (Laramie and Fort Steele, Wyoming, USA) to document their growth and survival. Cumulative differences between collections from invaded and noninvaded communities were species-specific. S. airoides displayed a consistent positive response to long-term coexistence with A. repens , whereas the performance of H. comata originating from invaded communities was not different from H. comata collected from noninvaded communities. In general, genets from invaded communities had fewer tillers than genets from noninvaded communities, but their relative tiller production (percent increase) was greater for genets from invaded communities at both field transplant sites for both grass species. Basal area increase and overall performance of collections from invaded and noninvaded communities of origin depended on transplant site and grass species. The results suggest that native species have the potential for adaptation to coexist with exotic invasives, although that potential may differ among species.     

Comparison of Polypeptide Synthesis in Leaf of Panicum repens Grown in Different Habitats

he polypeptide synthesis in leaf of Panicum repens L. grown naturally in different habitats was analyzed using SDS-PAGE. Preliminary experiment indicates that the overall changes in polypeptide synthesis were relatively small, but the synthesis of a 30.6 kD polypeptide was enhanced in P. repens grown in sandy beach (salinity 1.5% ～ 3.0 % ) and that of a 130 kD pelypeptide markedly decreased. However, the content of the 130 kD protein increased in P. repens grown in sandy farmlands (salinity 0.1%～0.3% ), especially in water marsh (salinity 0.3 % ～0.5 % ).     

Superoxide anion radical scavenging activities of herbs and pastures in northern Japan determined using electron spin resonance spectrometry

Free radicals are not only destructive to the living cells but also reduce the quality of animal products through oxidation. As a result the superoxide anion radical (O2-), one of the most destructive reactive oxygen species, is a matter of concern for the animal scientists as well as feed manufacturers to ensure the quality of product to reach consumers demand. The superoxide anion radical scavenging activities (SOSA) of water and MeOH extracts of 2 herbs and 9 pasture samples collected from lowland and highland swards were determined against a 5,5-dimethyl-1-pyroline-N-oxide-O2-spin adduct based on a hypoxanthine-xanthine oxidase reaction using electron spin resonance spectrometry. Both the water and MeOH extracted SOSA differed among the herbs and pastures. Species and altitudinal variations were observed between extraction methods. The herbs were higher in both water and MeOH extracted SOSA than the pastures except for water extracts of one pasture, white clover (Trifolium repens L.). Among the pastures, quackgrass (Agrophyron repens L.) showed higher SOSA in both the MeOH and water extracts, and timothy (Phleum pretense L.) showed higher MeOH extracted SOSA. It is apparent that the kind and amount of antioxidants differ among herbs and pastures. Animal health and quality of animal products could be improved by adequate selection and combining of herbs and pastures having higher SOSA.     

The Effects of Flavonoid Allelochemicals from Knapweeds on Legume–Rhizobia Candidates for Restoration

Russian knapweed ( Acroptilon repens ) and Spotted knapweed ( Centaurea maculosa ) are allelopathic weeds invasive in North American grasslands. Both species contain at least one phytotoxic flavonoid root exudate with demonstrated negative influences on other plants. Previous findings indicated that Silky lupine ( Lupinus sericeus ), among other legumes, was relatively resistant to Spotted knapweed invasion and allelochemistry. We hypothesized that legume species may exhibit resistance to flavonoids in knapweed root exudates and may serve as candidate species for management efforts. Because legumes form symbiotic relationships with rhizobia, these bacteria must also be evaluated for allelochemical resistance before legumes can be recommended for restoration. In this study, we examined four legume species for effects of 7,8-benzoflavone (from Russian knapweed) and (±)-catechin (from Spotted knapweed) on rhizosphere interactions involving legume roots and associated rhizobia. Pure cultures of four rhizobia strains exhibited varied responses when grown with 7,8-benzoflavone or (±)-catechin. Alfalfa ( Medicago sativa ) and its bacterial symbiont, Sinorhizobium meliloti , exhibited allelochemical resistance that varied with (±)-catechin concentration when grown in vitro. Four legume species were grown under greenhouse conditions. Plants that were inoculated and nodulated generally exhibited no response to 7,8-benzoflavone or (±)-catechin treatments. Plants that were not inoculated exhibited stronger responses. Therefore, inoculation and nodulation may confer resistance to allelochemicals. These results, when coupled with previous research and field observations, suggest that legumes may not be susceptible to knapweed allelopathy and may be good choices in restoration of knapweed infestations when inoculated, particularly on sites with low soil nitrogen.     

Promoter Extraction from GenBank (PEG): automatic extraction of eukaryotic promoter sequences in large sets of genes.

Promoter Extraction from GenBank (PEG) extracts promoter sequences for large sets of genes using information present in GenBank. For a gene whose promoter sequence is not found, PEG will attempt to extract promoter sequences of the orthologous genes instead. AVAILABILITY: It is freely available to academic users at ftp://cshl.org/pub/science/mzhanglab/theresa/. CONTACT: zhangt@cshl.org; mzhang@cshl.org