蔷薇科一些植物鲜叶提取物清除DPPH自由基活性的研究

用二苯基苦基苯肼自由基酶标仪法, 对亚热带蔷薇科常见的50种木本植物鲜叶的自由基清除活性进行了比较,发现不同属、不同种树木鲜叶的80%甲醇提取物的自由基清除活性有很大差异, 其中苹果属5种植物在相当于鲜叶浓度为0.5 mg/mL于37℃下孵育20 min时, 对0.5 mmol.L-1 DPPH自由基平均清除率达62.4%,而绣线菊属3种植物的平均自由基清除率仅11.6%。尖嘴林檎、棣棠、木瓜、三叶海棠、湖北海棠、木香花、小果蔷薇和黄山花楸等鲜叶有较强的自由基清除活性,它们在浓度为0.5 mg/mL时的自由基清除率分别可达85.0%、75.8%、70.7%、69.6%、64.5%、62.5%、61.8%和61.3%,显示其有较大的开发潜力。     

一些裸子植物鲜叶提取物清除自由基的活性研究

用二苯基苦基苯肼自由基酶标仪法,对常见的60余种裸子植物鲜叶的自由基清除活性进行了比较.发现不同科属,不同树种鲜叶的80%甲醇提取物的自由基清除活性有很大差异,其中罗汉松科罗汉松属树木鲜叶在浓度在0.5mg/mL,于37℃下孵育20min时的自由基清除率平均可达55.9%,而柏科侧柏属平均仅为7.1%;罗汉松,孔雀柏、小叶罗汉松、湿地松、杉木和刺柏等鲜叶有很强的自由基清除活性,它们的自由基清除率分别可达61.1%,58.4,57.6%,57.1%,51.8%和50.4%,表明这些树种有较大的开发潜力。     

一些单子叶木本植物鲜叶提取物清除DPPH自由基活性初探

研究用二苯基苦基苯肼自由基酶标仪法,对常见的三十余种单子叶木本植物鲜叶的自由基清除活性进行了比较,发现不同科属、不同种植物鲜叶的80％甲醇提取物对DPPH自由基的清除活性有很大差异,其中供试的棕榈科7种植物鲜叶提取物,在相当于鲜叶浓度为2．5mg／ml于37℃下孵育20min时,对0．5mmol／L DPPH自由基清除率平均可达40．0％,而龙舌兰科5种植物平均仅为7．2％;刺葵、棕竹、筋头竹、蒲葵和棕榈等鲜叶有较强的自由基清除活性,它们在相当于鲜叶浓度为2．5mg/ml时的自由基清除率分别可达83．1％、79．2％、64．9％、60．5％和51．3％。这些树种有一定的开发潜力。     

鸡骨草黄酮体外抗活性氧自由基作用的研究

对鸡骨草进行黄酮提取及抗活性氧自由基作用的研究。以70%乙醇为溶剂,超声波提取法提取鸡骨草中的黄酮;采用比色法测定鸡骨草黄酮对DPPH·和O-·2两种自由基的清除作用以及还原能力。鸡骨草黄酮对DPPH·和O-·2两种自由基都有明显的清除作用,清除能力为DPPH·O-·2;对Fe3+也具有较强的还原能力。清除率与浓度存在明显的量效关系,当黄酮的浓度为0.306 mg/mL时,其对O-·2清除率为12.57%;当黄酮的浓度为0.228 mg/mL时,其对DPPH·清除率为50%。对自由基的清除能力总体强弱是:DPPH·O-·2;还原Fe3+能力随黄酮的浓度增加而增强。     

煤绒菌原质团和菌核甲醇提取物抗氧化活性的研究

为探索黏菌的抗氧化活性,以总还原力、DPPH自由基清除率及O2自由基清除率为指标,首次对煤绒菌原质团和菌核甲醇提取物进行抗氧化活性研究。结果表明:煤绒菌原质团和菌核甲醇提取物均有较好的抗氧化活性,当质量浓度为0.8 mg/mL时,二者对O2自由基的清除能力最强,清除率分别为70.39%和86.83%;当质量浓度为0.4 mg/mL时,二者对DPPH自由基的清除能力最强,清除率分别为57.22%和62.91%,通过比较IC50值,菌核粗提物的抗氧化能力略优于原质团。     

黑灵芝提取物清除DPPH自由基的作用

以黑灵芝为研究对象,采用不同方法提取黑灵芝中的有效成分,以BHT和抗坏血酸为对照品,采用DPPH.法研究各种提取物对自由基的清除作用。结果表明:微波萃取法是最适合提取黑灵芝中有效成分的现代方法,不仅产率高,而且速度快,节能;不同溶剂提取物对DPPH自由基清除率强弱依次为95%乙醇>丙酮>水>氯仿,提取物用量与清除能力成量效关系;黑灵芝的丙酮提取物浓度达到1 mg/mL时已超过10 mg/mL BHT的抗氧化效果,相当于0.5 mg/mL浓度抗坏血酸的抗氧化效果。     

低聚壳聚糖衍生物的制备及其抗氧化性能

低聚壳聚糖(COS)经化学改性得到N-苯亚甲基壳聚糖(NBCOS)和O-2'-羟丙基三甲基氯化铵壳聚糖(OHCOS),对其结构进行表征.考察了COS及其衍生物对超氧阴离子O2¨、羟基自由基·OH、DPPH自由基的清除活性以及还原能力.结果表明:当浓度为10 mg/mL时,COS和OHCOS对O2¨的清除率分别为89.6%和85.5%,而同样浓度时NBCOS的清除率仅有6.9%;它们清除·OH和DPPH的活性大小顺序为COS>OHCOS>NBCOS,而还原能力大小顺序为COS>NBCOS>OHCOS.     

硬枝树花粗提物的抗氧化作用

采用DPPH和ABTS法对硬枝树花石油醚(30~60)、二氯甲烷、乙酸乙酯、甲醇等4个溶剂依次提取得到的浸膏物,进行抗氧化活性测定试验。结果表明:甲醇提取物,乙酸乙酯和二氯甲烷提取物在0.4~1.0 mg/mL检测浓度范围内对.DPPH的清除效果和质量浓度呈现一定的量效关系。甲醇提取物在1 mg/mL时,清除率高达93.99%,二氯甲烷提取物在1 mg/mL时清除率为92.32%,均高于同质量浓度的BHT。乙酸乙酯和二氯甲烷提取物在0.4~1.0mg/mL检测浓度范围内对ABTS.+自由基清除率与质量浓度呈现一定的量效关系,在1 mg/mL时,二氯甲烷提取物对ABTS.+自由基清除率为65.6%,乙酸乙酯提取物对ABTS.+自由基清除率为48%。     

蝉拟青霉代谢产物清除DPPH自由基和抗真菌活性的研究

用二苯代苦味肼基自由基(DPPH)-TLC法和酶标仪法对一株蝉拟青霉P3菌丝体和发酵液甲醇提取物的清除自由基活性进行了定性和定量测定,发现两种提取物具有较强的清除自由基活性,在浓度为5.0mg/mL,于37℃下保温10min时,两种样品对0.4mg/mL的DPPH自由基的清除率分别可达55.52%和74.86%.以一种黑曲霉菌为指示菌,采用薄层色谱法对蝉拟青霉菌丝体和发酵液甲醇提取物进行抑菌活性试验,实验中根据抑菌圈大小判定代谢物抑菌活性的大小.同时,以致病菌白色假丝酵母菌为指示菌,采用牛津杯法对提取物进行进一步抑菌活性验证,结果表明,菌丝体和发酵液提取物样品浓度为5.0mg/mL时,其抑菌圈直径分别可达11.23mm和21.42mm.     

红花寄生叶3种溶剂提取物清除自由基活性

采用4种方法测定了红花寄生(寄主桑树)叶的水、80%甲醇和80%丙酮提取物对自由基的清除活性,以芦丁和BHT为对照品。结果表明,3种提取物均具有较强的自由基清除能力,且表现出不同程度的量效依赖关系;在3种溶剂提取物中,80%甲醇提取物清除.OH和O2-.活性最强,半清除率浓度ρ(SC50)分别为0.212、0.139 mg/mL,而80%丙酮提取物则清除DPPH.和ABTS.+活性最强,ρ(SC50)分别为0.198、0.580 mg/mL。此外,3种溶剂提取物经酸水解后,HPLC均检出槲皮素和山奈酚等2种黄酮醇苷元,其含量范围分别为39.90～73.03 mg/g、4.82～9.19 mg/g间。可见,槲皮素及其苷类衍生物是红花寄生清除自由基活性的主要作用成分。     

The F1-ATPase inhibitor Inh1 (IF1) affects suppression of mtDNA loss-lethality in Kluyveromyces lactis

Loss of mtDNA by the petite-negative yeast Kluyveromyces lactis is lethal (rho(o)-lethality). However, mutations in the alpha, beta and gamma subunits of F(1)-ATPase can suppress lethality by increasing intramitochondrial hydrolysis of ATP. Increased hydrolysis of ATP can also occur on inactivation of Inh1, the natural inhibitor of F(1)-ATPase. However, not all strains of K. lactis show suppression of rho(o)-lethality on inactivation of INH1. Genetic analysis indicates that one or more alleles of modifying factors are required for suppression. Papillae showing enhanced resistance to ethidium bromide (EB) in INH1 disruptants have mutations in the alpha, beta and gamma subunits of F(1)-ATPase. Increased growth of double mutants on EB has been investigated by disruption of INH1 in previously characterized atp suppressor mutants. Inactivation of Inh1, with one exception, results in better growth on EB and increased F(1)-ATPase activity, indicating that suppression of rho(o)-lethality is not due to atp mutations preventing Inh1 from interacting with the F(1)-complex. By contrast, in suppressor mutants altered in Arg435 of the beta subunit, disruption of INH1 did not change the kinetic properties of F(1)-ATPase or alter growth on EB. Consequently, Arg435 appears to be required for interaction of Inh1 with the beta subunit. In a previous study, a mex1-1 allele was found to enhance mgi(atp) expression. In accord with results from double mutants, it has been found that mex1-1 is a frameshift mutation in INH1 causing inactivation of Inh1p.     

小麦遗传背景对黑麦抗叶锈基因Lr26的抗性表达的影响

利用1套从小麦纯系和黑麦自交系培育出的1R附加系、代换系和易位系,研究了1RS上的抗叶锈基因Lr26在小麦中的表达。结果发现,1R二体附加系和纯合1RS/1BL易位系高抗小麦叶锈病;而其小麦亲本、1R(1B)代换系和1BS/1RL易位系重感叶锈病。这一结果指出了黑麦染色体臂1RS上的抗小麦叶锈病基因Lr26在小麦中的表达受小麦染色体臂1BL上的基因的强烈影响,指出了外源基因在小麦中的表达可受染色体臂或基因水平上的相互作用的制约。文中讨论了外源基因与小麦遗传背景相互作用在小麦育种中的意义。     

Exploring the limits of sequence and structure in a variant betagamma-crystallin domain of the protein absent in melanoma-1 (AIM1)

βγ-Crystallins belong to a superfamily of proteins in prokaryotes and eukaryotes that are based on duplications of a characteristic, highly conserved Greek key motif. Most members of the superfamily in vertebrates are structural proteins of the eye lens that contain four motifs arranged as two structural domains. Absent in melanoma 1 (AIM1), an unusual member of the superfamily whose expression is associated with suppression of malignancy in melanoma, contains 12 βγ-crystallin motifs in six domains. Some of these motifs diverge considerably from the canonical motif sequence. AIM1g1, the first βγ-crystallin domain of AIM1, is the most variant of βγ-crystallin domains currently known. In order to understand the limits of sequence variation on the structure, we report the crystal structure of AIM1g1 at 1.9 Å resolution. Despite having changes in key residues, the domain retains the overall βγ-crystallin fold. The domain also contains an unusual extended surface loop that significantly alters the shape of the domain and its charge profile. This structure illustrates the resilience of the βγ fold to considerable sequence changes and its remarkable ability to adapt for novel functions.     

产脂酵母产脂培养条件研究及脂肪检测方法初探

目的：研究产脂酵母产脂条件及脂肪提取方法。方法：探讨了单因素如：pH、碳源、氮源、葡萄糖浓度、金属微量元素等对其产脂能力的影响,并进行了正交试验;脂肪测定方法研究,用对比分析法,并对其中的方法加以改进,采用光谱扫描以确定酵母脂肪最大吸收波长。结果：试验范围所得酵母产脂最佳条件是：接种量3%,MnCl_2 0．05%、FesO_4 0．04%、(NH_4)_2SO_4 0．3%、葡萄糖2%、pH 6．5,培养5d,45ml的发酵液其油脂的吸光度(252nm)可达2．4082;酵母脂肪最大吸收波长为252nm,在此波长下测定,获得了快速、准确的结果。结论：所得产脂条件可为进一步的开发研究打下基础。研究出的酵母脂肪测定方法,是一种快速、简便的方法,可满足产脂酵母菌种筛选和产脂条件研究的需要。     

Mutagenesis of the catalytic subunit of rabbit muscle protein phosphatase-1

We have generated site-directed mutants of the catalytic subunit of rabbit muscle ppase-1. Since it is known that ppase-1 and ppase-2A are highly susceptible to inactivation by sulfhydryl reagents, we have mutagenized the six cysteine residues conserved between these two enzymes to serines. The six mutants were purified to near homogeneity by affinity chromatography on inhibitor-2-Sepharose and characterized. All six exhibited enzymatic activity. These results indicate that the catalytic mechanism of ppase-1 is different from that of the protein tyrosine phosphatases which involve a cysteinyl phosphate intermediate.     

Stoichiometry studies reveal functional properties of KDC1 in plant shaker potassium channels

Functional heteromeric plant Shaker potassium channels can be formed by the assembly of subunits from different tissues, as well as from diverse plant species. KDC1 (K(+) Daucus carota 1) produces inward-rectifying currents in Xenopus oocytes when coexpressed with KAT1 and other subunits appertaining to different plant Shaker subfamilies. Owing to the presence of KDC1, resulting heteromeric channels display slower activation kinetics, a shift of the activation threshold toward more negative membrane potentials and current potentiation upon the addition of external zinc. Despite available information on heteromerization of plant Shaker channels, very little is known to date on the properties of the various stoichiometric configurations formed by different subunits. To investigate the functional properties of heteromeric nKDC1/mKAT1 configurations, we realized a series of dimeric constructs combining KDC1 and KAT1 alpha-subunits. We found that homomeric channels, formed by monomeric or dimeric alpha-subunit constructs, show identical biophysical characteristics. Coinjections of diverse tandem constructs, instead, displayed significantly different currents proving that KDC1 has high affinity for KAT1 and participates in the formation of functional channels with at most two KDC1 subunits, whereas three KDC1 subunits prevented the formation of functional channels. This article brings a contribution to the understanding of the molecular mechanisms regulating plant Shaker channel functionality by association of modulatory subunits.     

Toxicity of 4-Nitroquinoline 1-Oxide for Crithidia fasciculata

Growth inhibition of Crithidia fasciculata by 4-nitroquinoline 1-oxide (NQO) was observed in defined and complex media at 28 C. Aromatic amino acids, cysteine, and nicotinic acid, among several other substances, were ineffective in overcoming NQO toxicity. Dicoumarol and bovine albumin reversed NQO inhibition. While bovine albumin probably acted by the extra-cellular binding of NQO, dicoumarol inhibited the activity of DT-diaphorase, which reduces NQO to 4-hydroxyaminonitroquinoline 1-oxide (HAQO). The DT-diaphorase from C. fasciculata had the same characteristics as the enzyme from rat liver. The specific protection by dicoumarol against NQO inhibition suggests that HAQO is the active toxic substance for C. fasciculata.     

The Ene Reaction of Singlet Oxygen with Olefins

The reactions of singlet oxygen (¹O₂) with cis and trans butenes-1,1,1-d₃, at—80°C in Freon-11, show a product isotope effect (k_H/k_D) of 1.38 and 1.25 respectively. Isomerization of the starting materials or formation of dioxetanes were not observed during the course of the photooxygenation. Together with the isotope effects on the reactions of tetramethylethylene-d₆ isomers with singlet oxygen, these results require the reversible formation of a perepoxide or charge transfer intermediate.     

烫伤对大鼠下丘脑室旁核内皮素—1合成和分泌的影响

目的研究烫伤后下丘脑室旁核(PVH)内皮素-1(ET-1)的合成和分泌改变,探讨PVHET-1在烫伤中的病理生理学意义。方法用原位杂交和免疫组织化学方法观察了烫伤后PVHET-1合成和分泌的变化,并用通用图象颗粒分析法检测单位面积内ET-1mRNA阳性杂交信号的强度和ET-1样免疫反应物(ET-1-ir)免疫反应强度。结果烫伤后15minPVH神经元胞浆内ET-1mRNA阳性杂交信号与对照组相比未见明显差异,烫伤后60min和180minPVH神经元胞浆内ET-1mRNA阳性杂交信号较对照组(100％±25％)明显增多,强度明显增高,分别为138％±26％(P<0．05)和167％±18％(P<0.01);而烫伤后15minPVH神经元胞浆内ET-1阳性反应物明显减少,免疫反应物强度为6．3％±1．5％,显著低于对照组(P<0．01),烫伤后60min和180min逐渐回升,分别为23．1％±2．9％和44．1％±3．8％,但仍显著低于对照组(P＜0．01)。结论烫伤后PVHET-1合成和分泌增加。