尼日利亚螫毛果(Cnestis ferruginca)中一种具有清除自由基的活性化合物的分离鉴定

用二苯基苦基苯肼自由基薄层实验法（DPPH-TLC-ASSAY）,从尼日利亚螫毛果（Cnestis ferruginca)植物的甲醇提取物中发现了一种具有很强的清除自由基活性的物质;用柱色谱及反相制备柱色谱（RP-LPPLC）,制备出了该活性物质的纯品;用质谱（HR ESI-MS）,核磁共振氢谱（^1H0,碳谱（^13C,DEPT)。紫外光谱及化学方法对该物质进行了结构鉴定,鉴定结果为对苯酚基-6-O-反式咖啡酸基-β-D-吡喃葡萄糖甙。     

一种被毛孢(Hirsutella sp.)培养液中自由基清除剂的分析、分离和制备

[目的]在一次对虫生真菌代谢物进行大规模的清除自由基活性物质筛选中,发现一种被毛孢(Hirsutella sp.)菌株RCEF0881发酵液中存在有较强的清除自由基活性物质.本研究目的是初步搞清这些活性成分的具体组成,并制备出一定量的纯品用于进一步的结构鉴定.[方法]用有机溶剂法提取活性成分;用二苯基苦基苯肼自由基(DPPH)酶标仪法和薄层色谱法进行活性测定;用高分辨液质联用方法进行活性成分初步分析和鉴定;用反相制备色谱法制备活性组分.[结果]提取实验结果表明具清除自由基活性的物质能较好地被乙酸乙酯提取出来;液相色谱-质谱-活性测定分析表明提取物中活性组分的可能分子式分别为C7H6O4、C8H8O3和C12H14N2O.结合色谱特性、紫外光谱特征、质谱碎片和数据库查询可初步推断它们分别为二羟基苯甲酸、羟基甲基苯甲酸和生物碱类物质,但具体结构还有待于进一步确认.从高效液相色谱和质谱离子流的峰面积可知上述3种活性物质中C12H14N2O的含量最高.本研究成功地用反相制备色谱制备出该天然活性组分的纯品.该3种清除自由基活性物质都是首次发现存在于虫生真菌的代谢物中.     

对黄豆苷原具转化作用的耐氧突变株Aeroto-AUH-JLC140未知代谢产物分离、鉴定及抗氧化活性测定

【目的】与原出发菌株AUH-JLC140相比,耐氧突变株Aeroto-AUH-JLC140在其生长过程中产生一种未知物质,且该未知物质的产生与添加底物黄豆苷原无关。对该未知物质进行分离纯化和结构鉴定,并测定其产生动态及抗氧化活性。【方法】利用高效液相色谱对未知物质进行分离,经紫外吸收图谱、质谱、核磁共振氢谱和碳谱等分析,对未知物质进行结构鉴定;通过1,1-二苯基-2-苦味酰基自由基(DPPH)清除试验测定其抗氧化活性。【结果】Aeroto-AUH-JLC140产生的未知物质被鉴定为吲哚,接种后15 h菌株产吲哚最高,所产吲哚量为19.89 mg/L。浓度为0.2 mmol/L(即23.40 mg/L)的吲哚除对DPPH自由基具有明显清除作用外,还能有效降低脑心浸液(BHI)液体培养基的氧化-还原电位。【结论】耐氧突变株Aeroto-AUH-JLC140产生的未知代谢产物为吲哚,菌株通过产生吲哚降低培养基氧化-还原电位,进而为该菌株的生长提供适宜的低氧微环境。     

阳春砂多糖的分离纯化及体外抗氧化作用研究

本实验研究了阳春砂多糖(AVP)及其纯化组分的抗氧化活性,首先采用DEAE-纤维素-52离子交换柱分级洗脱阳春砂粗多糖,再采用Sephadex G-100葡聚糖凝胶色谱柱进一步纯化得到纯化多糖;分别采用超氧阴离子自由基体系、羟基自由基体系、1,1-二苯基苦基苯肼自由基体系,对阳春砂多糖的抗氧化活性进行研究,并以维生素C为阳性对照物,实验结果表明阳春砂粗多糖及纯化组分对超氧阴离子自由基、羟基自由基、1,1-二苯基苦基苯肼自由基均有较强的清除能力,AVP-3体外抗氧化活性最强。     

金顶侧耳次级代谢产物及抗氧化活性研究(英文)

采用硅胶柱色谱、ODS柱色谱、Sephadex LH-20柱色谱、HPLC等分离方法,对金顶侧耳大米发酵乙酸乙酯提取物进行分离;通过HR-ESI-MS、1H-NMR和13C-NMR等光谱学方法对其结构进行鉴定。并检测铁氰化钾还原能力、1,1-二苯基-2-苦基苯肼(DPPH)自由基清除能力和亚铁离子螯合能力。从金顶侧耳大米发酵粗提物中分离鉴定了吲哚甲醛、苯肽等6个化合物,吲哚甲醛为首次从该菌中分离得到,活性测试表明金顶侧耳粗提取物具有一定的还原能力,其大米发酵产物有可能开发成为一种新型功能性食品。     

极地海洋真菌赛氏曲霉活性成分研究

通过对菌株r DNA-ITS序列和系统发育多样性进行分析,鉴定该菌株为赛氏曲霉;对赛氏曲霉用大米培养基进行固体发酵培养,对其发酵产物采用有机溶剂萃取、硅胶柱色谱层析、反相ODS柱色谱层析、薄层色谱层析、Sephadex LH-20凝胶柱色谱层析和制备型高效液相色谱等分离纯化手段进行分离,得到7个单体化合物。对分离得到单体化合物采用质谱、核磁共振氢谱、核磁共振碳谱、二维核磁共振等现代波谱技术对其进行结构鉴定;对单体化合物的MIC值进行测定,其中化合物L-1对耐甲氧西林金黄色葡萄球(MRSA)、耐甲氧西林表皮葡萄球菌(MRSE)有一定的抑菌活性,对大肠杆菌有明显的抑菌活性。     

糙叶五加正丁醇萃取部位抗炎活性成分研究

本文对糙叶五加果实正丁醇萃取物的抗炎活性成分进行研究.采用硅胶柱色谱、C18柱色谱、LH-20型羟丙基葡聚糖凝胶(Sephadex LH-20)柱色谱、半制备液相及重结晶等方法进行分离纯化,利用波谱分析结合理化性质鉴定化合物的结构.从糙叶五加果实正丁醇萃取部位中分离鉴定出17个化合物,分别为槲皮素-3-O-β-D-吡喃...     

云南兔儿风的五环三萜类化学成分研究

以采自云南省楚雄自治州楚雄市的云南兔儿风(Ainsliaea yunnanensis)干燥地上部分为研究对象,应用现代色谱手段(硅胶柱色谱、ODS柱色谱、Sephadex LH-20凝胶柱色谱、制备液相及制备薄层色谱等),从云南兔儿风植物中分离单体化合物,运用光谱分析技术(MS、1 H-NMR、13 C-NMR、DEPT、COSY、HSQC、HMBC、ROSEY)鉴定其化学结构,对云南兔儿风的化学成分进行研究,为兔儿风属植物研究及植物开发利用提供一定的物质基础。结果表明:从云南兔儿风乙醇提取物中共分离得到了11个五环三萜类化合物,分别鉴定为α-香树脂醇乙酸酯(1)、羽扇豆醇乙酸酯(2)、9,12-二烯乌苏烷乙酸酯(3)、α-香树脂酮(4)、羽扇豆烯酮(5)、蛇菰素B(6)、降香萜醇乙酸酯(7)、齐墩果烷-11-羰基-12-烯-3-醇棕榈酸酯(8)、12-烯基白桦脂醇(9)、西米杜鹃醇(10)、二十烷酸羽扇豆醇乙酸酯(11)。其中,化合物1~6,9~11均为首次从该植物中分离得到。通过对云南兔儿风化学分进行深入研究,明确其主要的活性成分,阐明云南兔儿风药用植物中抗炎活性物质基础,为相关的新药科研工作及产品开发提供重要的科学依据。     

地枇杷的化学成分及抗氧化活性研究CSCD

本文对土家族民间药材地枇杷进行化学成分及抗氧化活性研究。运用硅胶柱色谱、凝胶柱色谱、大孔树脂柱色谱结合半制备高效液相色谱等手段对其乙醇提取物进行分离纯化,利用核磁共振波谱、质谱等方法对化合物进行结构鉴定,分离得到17个化合物,分别鉴定为高山金莲花素(1)、(+)-儿茶素(2)、异紫花前胡苷(3)、补骨脂素(4)、佛手柑内酯(5)、(+)-南烛木树脂酚-3α-O-β-D-葡萄糖苷(6)、(+)-南烛木树脂酚-3α-O-β-D-吡喃木糖苷(7)、异落叶松脂素-9-O-β-D-吡喃葡萄糖苷(8)、ssioriside(9)、华中冬青素(10)、异落叶松脂素(11)、(7R,8S)-3,5′-二甲氧基-4′,7-环氧-8,3′-新木脂烷-5,9,9′-三醇(12)、6,7-二甲氧基-4-羟基-1-萘甲酸(13)、3,4-二羟基苯甲酸乙酯(14)、bluemenol A(15)、3,3′,4,4′-四羟基联苯(16)、绿原酸乙酯(17)。化合物1~4、6~17为首次从该植物中分离得到。使用DPPH自由基清除率、总抗氧化能力、超氧阴离子清除能力三个指标来测定17个化合物的抗氧化活性。结果显示木脂素类化合物9、10,多酚类化合物13、14、16具有良好的DPPH自由基清除能力及总抗氧化能力,表现出的抗氧化活性与同浓度抗坏血酸活性相当。     

一种白僵菌代谢产物中生物活性物质的研究 Ⅰ.具有清除自由基的活性物质的分离和制备

通过对白僵菌 Beauveria sp. 的液体培养及生物活性测定,发现该菌代谢产物具有较强的清除自由基的活性,我们用甲醇成功地提取出该活性成分,同时用色谱等方法对该活性成分进行了分离和制备,并用高压液相色谱法和DPPH薄层试验对其纯度及活性进行了检验,得到了具消除自由基活性的纯化合物：P-24-3。     

Nitric oxide reduces Cu toxicity and Cu-induced NH4+ accumulation in rice leaves

Nitric oxide (NO) is a highly reactive, membrane-permeable free radical, which has recently emerged as an important antioxidant. Here we investigated the protective effect of NO against the toxicity and NH₄⁺ accumulation in rice leaves caused by excess CuSO₄ (10 mmol L⁻¹). It was found that free radical scavengers (sodium benzoate, thiourea, and reduced glutathione) reduced the toxicity and NH₄⁺ accumulation in rice leaves caused by excess CuSO₄. NO donor sodium nitroprusside (SNP) was also effective in reducing CuSO₄-induced toxicity and NH₄⁺ accumulation in rice leaves. The protective effect of SNP on the toxicity and NH₄⁺ accumulation can be reversed by 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethyl- imidazoline-1-oxyl-3-oxide, a NO scavenger, suggesting that the protective effect of SNP is attributable to NO released. Results obtained in the present study suggest that reduction of CuSO₄-induced toxicity and NH₄⁺ accumulation by SNP is most likely mediated through its ability to scavenge active oxygen species.     

酸雨对温州三土羊湿地水体氮营养盐数量的影响

为了解酸雨对温州三垟湿地水体氮营养盐数量的影响,本文测定了三垟湿地水体中不同形态氮的含量,其中氨氮2.90～10.75 mg·L^-1,平均5.38 mg·L^-1、硝态氮0.16～0.44 mg·L^-1,平均0.31 mg ·L^-1;总氮34.04～63.20 mg·L^-1,平均55.75 mg·L^-1和水体的pH值,6.1～6.5,平均6.4;并测算了近两年通过降水输入到三垟湿地和三垟湿地水体中不同形态氮的数量及其占湿地现有水体中各形态氮的比例,其中输入到三垟湿地氨氮、硝态氮和总氮的量分别为2.8～2.86× 10 kg、2.87×10⁴～4.96×10⁴kg和5.35×10⁴～7.82×10⁴ kg,分别占湿地水体现有量的56%～6%、11.21～19.38倍和12%～17%;直接输送到三垟湿地水体各形态氮的数量0.72×10⁴～0.8×10⁴ kg、0.83×10⁴～1.44×10⁴ kg和1.55×10⁴～2.27×10⁴,分别占现有量的16%～19%,3.24～5.63倍和3%～5%.结果表明,酸雨是三垟湿地水体氮污染的主要来源之一,对三垟湿地水体富营养化产生重要影响.     

Hemoglobin: A mechanism for the generation of hydroxyl radicals

Oxyhemoglobin (HbO₂) reduces Fe(III) NTA aerobically to become methemoglobin (metHb) and Fe(II)NTA. These conditions are favorable for the generation via Fenton chemistry of the hydroxyl radical that was measured by HPLC using salicylate as a probe. The levels of hydroxyl radicals generated are a function of both the percent metHb formed and the chemical nature of the buffer. The rates of formation of both metHb and hydroxyl radicals were dependent upon the concentration of Fe(III)NTA. Of the buffers tested, HEPES was the most effective scavenger of hydroxyl radicals while the other buffers scavenged in the order: HEPES > Tris > MOPS > NaCl ≈ unbuffered. The addition of catalase to remove H₂0₂ or bathophenanthroline to chelate Fe(II) inhibited virtually all hydroxyl radical formation. Carbonyl formation from free radical oxidation of amino acids was found to be 0.1 mol/mol of hemoglobin. These experiments demonstrate the ability of hemoglobin to participate directly in the generation of hydroxyl radicals mediated by redox metals, and provide insight into potential oxidative damage from metals released into the blood during some pathologic disorders including iron overload.     

DPPH free radical scavenger components from the fruits of Alpinia rafflesiana Wall. ex. Bak. (Zingiberaceae)

The methanol extract of the dried ripe fruits of Alpinia rafflesiana was investigated for its DPPH free radical scavenger constituents. 2',3',4',6'-Tetrahydroxychalcone (7), which has never been isolated from natural sources was found to be most active as a DPPH free radical scavenger with the IC50 value of 55 microM. Other known compounds isolated from this species include 5,6-dehydrokawain (1), flavokawin B (2). 1,7-diphenyl-5-hydroxy-6-hepten-3-one (3), (-)-pinocembrin (4), cardamonin (5) and (-)-pinostrobin (6). The DPPH free radical scavenger compounds were detected using TLC autographic analysis. The percentage inhibition of DPPH free radical scavenging activity was measured on isolates (5-7) using colorimetric analysis.     

Antioxidant activity of galloyl quinic derivatives isolated from P. lentiscus leaves

The antioxidant properties of galloyl quinic derivatives isolated from Pistacia lentiscus L. leaves have been investigated by means of Electron Paramagnetic Resonance spectroscopy (EPR) and UV-Vis spectrophotometry. Antioxidant properties have been also estimated using the biologically relevant LDL test. The scavenger activities of gallic acid, 5- O -galloyl, 3,5- O -digalloyl, 3,4,5- O -trigalloyl quinic acid derivatives, have been estimated against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, superoxide ( O 2 - ) radical, and hydroxyl (OH) radical. On the whole, the scavenger activity raised as the number of galloyl groups on the quinic acid skeleton increased. The half-inhibition concentrations (IC 50 ) of di- and tri-galloyl derivatives did not exceed 30 μM for all the tested free radicals. All the tested metabolites strongly reduced the oxidation of low-density lipoproteins (LDL), following a trend similar to that observed for the scavenger ability against OH radical.     

Electron spin resonance and spin trapping technique provide direct evidence that edaravone prevents acute ischemia-reperfusion injury of the liver by limiting free radical-mediated tissue damage

A novel free radical scavenger, 3-methyl-1-phenyl-2-pyrazolin-5-one (edaravone), is used for the treatment of acute ischemic stroke and is protective in several animal models of organ injury. We tested whether edaravone is protective against acute liver warm ischemia/reperfusion injury in the rat by acting as a radical scavenger. When edaravone was administered prior to ischemia and at the time of initiation of the reperfusion, liver injury was markedly reduced. Production of oxidants in the liver in this model was assessed in vivo by spin-trapping/electron spin resonance (ESR) spectroscopy. Ischemia/reperfusion caused an increase in free radical adducts rapidly, an effect markedly blocked by edaravone. Furthermore, edaravone treatment blunted ischemia/reperfusion-induced elevation in pro-inflammatory cytokines, infiltration of leukocytes and lipid peroxidation in the liver. These results demonstrate that edaravone is an effective blocker of free radicals in vivo in the liver after ischemia/reperfusion, leading to prevention of organ injury by limiting the deleterious effects of free radicals.     

Spin-trapping studies with MTDO, a dihydroquinoline type radical scavenger

The effect of MTDQ, a dihydroquinoline type free radical scavenger was studied in biological membranes, and model systems. Using spin-labelling and spin-trapping methods, it was that MTDQ induced a decrease of the mobility of spin labels attached to the thiol sites of membrane proteins, and it was a strong free radical scavenger in hydroxyl and superoxide anion free radical generating systems. The experimental results suggest that the presence of MTDQ in the cell membranes may improve the protection of membrane components against free radical attacks.     

新的C4及CAM光合途径植物

以稳定性碳同位素比(δ¹³C)鉴别禾本科、莎草科、苋科和萝摩科共46种植物的光合作用途径,发现了36种新的C₄植物(δ¹³C-10.43到-13.66‰)和1种CAM植物(δ¹³C-15.24‰)。根据Hattersley区分C₄植物三种亚类型的不同δ¹³C值,提出在36种C₄中有8种具δ₁₃C值-10.4到-10.9‰者是NADP-ME型,6种具δ¹³C值-13‰左右的是NAD-ME型,其余种类可能是NADP-ME或PCK型。     

Visible light damage to Escherichia coli in seawater: oxidative stress hypothesis

The effect of visible light on Escherichia coli H10407 in seawater microcosms was investigated. Light damage was estimated by loss of colony-forming ability. Illumination of E. coli suspended in oligotrophic seawater with visible light at an intensity of about 40 klux caused a drastic decrease of culturable bacteria which turned to a viable but non-culturable state. In seawater E. coli exhibited weak metabolic activity as estimated by ³H methyl-thymidine incorporation in the cell. Visible light did not significantly alter this metabolic activity and did not involve detectable oxidation of lipid membranes as evaluated by gas chromatography analysis of fatty acids. The involvement of oxygen and reactive oxygen species in phototoxicity was studied. A decrease of the toxic effect was observed when E. coli was exposed to visible light under anaerobic conditions. Scavengers of reactive oxygen species exhibited variable protective effects. β-Carotene, a singlet oxygen scavenger, and superoxide dismutase were equally ineffective. On the other hand, catalase, which eliminates hydrogen peroxide and thiourea, a hydroxyl radical scavenger, showed a net protection. In addition desferrioxamine B, an iron chelator, was also effective in reducing phototoxicity, probably by preventing hydroxyl radical generation by decomposition of hydrogen peroxide in the presence of iron (Fenton reaction). Therefore, hydrogen peroxide and hydroxyl radical seem to be reactive intermediates of oxygen-dependent (type II) photosensitized reactions.     

Studies on the Antioxidant and Free Radical Scavenging Properties of Idb 1016 A New Flavanolignan Complex

Silybin has been complexed in 1:1 ratio with phosphatidyl choline to give IdB 1016 in order to increase its bioavailability. The antioxidant and free radical scavenger action of this new form of silybin has beenn evaluated.

One hour after the intragastric administration to rats of IdB 1016 (1.5g/kg b.wt.) the concentration of silybin in the liver microsomes was estimated to be around 2.5°g/mg protein corresponding to a final concentration in the microsomal suspension used of about 10°M. At these levels IdB decreased by about 40% the lipid peroxidation induced in microsomes by NADPH, CC1₄ and cumene hydroperoxide, probably by acting on lipid derived radicals. Spin trapping experiments showed, in fact, that the complexed form of silybin was able to scavenge lipid dienyl radicals generated in the microsomal membranes. In addition, IdB 1016 was also found to interact with free radical intermediates produced during the metabolic activation of carbon tetrachloride and methylhydrazine.

These effects indicate IdB 1016 as a potentially protective agent against free radical-mediated toxic damage.