竹红菌甲素对红细胞膜的光损伤

光敏化剂竹红菌甲素在可见光区有三个吸收峰,其波长为475nm、545nm和585nm。在有竹红菌甲素存在时,红细胞膜样品用250W碘钨灯照射,其光强度为48尔格/平方毫米·秒。辐照后观察到以下一些效应:1)膜蛋白SH基含量减少。2)膜蛋白敏感的氨基酸残基,如组氨酸、半胱氨酸和色氨酸含量降低。3)膜蛋白发生光??聚集作用。4)多聚不饱和类脂发生过氧化作用。竹红菌甲素光照不同时间后和竹红菌甲素光照后放置一段时间,再加到红细胞膜中,均能观察到膜蛋白SH基含量降低。提示竹红菌甲素的光氧化产物是稳定的,能引起红细胞膜的光损伤。     

北醌化合物的光敏活性及其抗肿瘤机制

苝醌 (ｐｅｒｙｌｅｎｅｑｕｉｎｏｎｅ ,ＰＱ)化合物是一类分布于自然界生物中的光敏色素。ＰＱ类光敏色素是目前已知的在可见光区内优良的光敏剂 ,近年来的研究证明其具有良好的光敏杀伤肿瘤细胞和抑制艾滋病病毒 (ＨＩＶ 1 )的作用[1～ 4] 。1 .醌类化合物的光敏活性真菌能产生具有ＰＱ骨架的代谢产物 ,陈远滕先生报道竹红菌的光敏作用。安静仪报道竹红菌甲素 (ｈｙｐｏｃｒｅｌｌｉｎＡ ,ＨＡ)有产生1Ｏ2 的作用。张志义发现ＨＡ能产生Ｏ-2·、·ＯＨ和ＨＡ-,提出ＨＡ对生物系统的光敏损伤机制与上述多重作用有关[5 ] 。第五振军等报…     

活性氧对疟原虫的杀伤作用

活性氧族(Reactive oxygen species,简称为ROS)是一组包括过氧化氢(H_2O_2)、超氧化物阴离子(O~-_2)、单线态氧(~1O_2)、羟自由基(·OH)在内的具有杀伤作用的细胞氧化代谢产物。免疫系统的多种效应细胞在受到合适刺激时均能产生和释放ROS。自1982年8月     

竹红菌乙素光敏作用对于小鼠肝癌细胞内游离钙浓度的影响

本文用Quin 2/AM荧光探针作为细胞内部钙离子指示剂,研究了竹红菌乙素光敏损伤后引起小鼠腹水肝癌细胞的钙离子浓度变化。实验结果表明,细胞内的钙离子浓度随着乙素光敏作用增强而上升。并且钙离子浓度的升高与细胞的存活率下降呈正比关系;用数种单线态氧淬灭剂(L-His,NaN_3);羟自由基清除剂(PABGA)观察了乙素光敏过程中产生的活性氧与细胞内的钙离子浓度增加相关。用膜去极化方法研究了细胞在光敏损伤过程中钙离子浓度变化与去极化的关系。     

SOD与化妆品

SOD是生物机体内的一种酶,即过氧化物歧化酶(Superoxide Dismutase;EC.1·15·1·1简称SOD)它在生物体内的主要作用是清除氧自由基O_2(H_2O_2+O_2→OH+OH+O_2,此反应称为Haber—Weiss反应)。因为在正常机体内与生物功能有关的氧化作用会大量地产生     

竹黄化学成分的研究

利用各种常规色谱分离技术对竹黄(Shiraia bambusicola)干燥子实体的甲醇/氯仿(v:v=1∶1)溶液中分离得到5个化合物。经波谱分析分别鉴定为竹红菌甲素(1)、竹红菌乙素(2)、竹红菌丙素(3)、竹红菌丁素(4)和macrosphelides A(5)。     

慢性肾衰病人血清和红细胞抗氧化能力的ESR研究

用电子自旋共振(ESR)自旋捕集技术研究了正常人和肾衰病人血清和红细胞对黄嘌呤 黄嘌呤氧化酶体系产生的氧自由基的作用.结果发现:(1)正常人血清和红细胞能够有效地清除超氧阴离子自由基(O_2~-),而肾衰病人血清和红细胞清除O_2~-的能力明显比正常人血清和红细胞低;(2)正常人血清能有效地把黄嘌呤 黄嘌呤氧化酶体系产生的O_2~-转化为·OH,病人血清在这方面与正常人血清有显著性差异.     

竹红菌光敏作用的初步探讨*

用纸片法作为筛选光敏物质及光敏作用的研究方法。结果证实了(1)竹红菌Hypo crella bambusae中含有对革兰氏阳性细菌具光敏活性的成分;(2)从中筛选到一种红色的光敏色素,属苝醌的一个新的衍生物,取名竹红菌甲素(Hypocrellin A简称“甲素”);(3)揭示了“甲素”是对可见光敏感、作用光谱较宽的光动力学(photodynamic)物质。从化合物的类型、光敏特性、治疗方法、治疗对象及其效果看,可以认为甲素是一新型的光化学疗法药物。     

竹红菌光敏作用的初步探讨

用纸片法作为筛选光敏物质及光敏作用的研究方法。结果证实了(1)竹红菌Hypo crella bambusae中含有对革兰氏阳性细菌具光敏活性的成分;(2)从中筛选到一种红色的光敏色素,属苝醌的一个新的衍生物,取名竹红菌甲素(Hypocrellin A简称“甲素”);(3)揭示了“甲素”是对可见光敏感、作用光谱较宽的光动力学(photodynamic)物质。从化合物的类型、光敏特性、治疗方法、治疗对象及其效果看,可以认为甲素是一新型的光化学疗法药物。     

竹红菌乙素对人红细胞Na~+-K~+ATPase和钠通透性光敏损伤的研究

本文用NMR和生化方法研究了竹红菌乙素对人红细胞膜Na~+-K~+ATPase和钠通透性的光敏损伤。结果表明:在通常情况下,可同时观察到乙素对Na~+-K~+ATPase和钠通透性的光敏损伤。比较乙素、甲素、原卟啉和胆红素对上述两项指标的光敏能力,发现乙素对Na~+-K~+ATPase损伤能力与甲素和原卟啉相当,比胆红素大,对钠通透性的损伤大于其它几种敏化剂。实验指出,Na~+-K~+ATPase活力下降比钠通透性增加敏感。在乙素光敏作用时,加入Vit E可基术上保持胞内钠离子浓度不变,但无法使Na~+-K~+ATPase活力不损伤,这表明膜磷脂的结构完整对保持胞内钠浓度比较重要。对照试验指出乙素可使Na~+-K~+ATPase暗失活,这可能是经乙素介导的,由膜还原物质向氧的电子传递生成活性氧自由基攻击靶分子所致。     

竹红菌乙素修饰物（－乙醇胺）对于腹水肝癌细胞光敏损伤的研究

通过竹红菌乙素修饰物（－乙醇胺,简称ＨＢ－Ｅ）对小鼠腹水肝癌细胞光敏损伤以及ＨＢＥ被ＡＨ细胞摄取过程的研究,结果表明,ＨＢ－Ｅ在６４０ｎｍ光照的条件下对ＡＨ细胞产生很强的光动力作用,细胞对ＨＢ－Ｅ的摄取速度快（室温下２ｍｉｎ,达到平衡）在饱和时每个细胞可摄取ＨＢ－Ｅ分子５×１０＾９个;经多种竹红菌素修饰物光敏能力的比较中ＨＢ－Ｅ光敏作用明显要大于其它的光敏剂,光敏机理的研究中确定了活性氧的作用是存     

A method to evaluate the antioxidant system for radicals in erythrocyte membranes

The erythrocyte defense system against cellular oxidants is complex and efficient. Free radicals generated in cell membranes, however, are relatively sequestered from the cell's antioxidant mechanisms. When an oxidant challenge exceeds the capacity of the erythrocyte's antioxidant system, membrane damage may occur, causing red cell destruction and hemolytic anemia. In this study, we present a method for monitoring radical reduction in erythrocyte membranes, using fatty acid spin labels with nitroxide radicals on the hydrocarbon chains. About 50 microL of packed (about 5-6 x 10(8)), carbon monoxide (CO)-gassed red blood cells are used. The electron paramagnetic resonance signals of the 5-doxylstearic acid spin labels in the intact cells are obtained as a function of time, at 37 degrees C over a period of 2 h. The pseudo first-order rate constant for reduction of the spin label in normal adult intact cells under our experimental conditions is 4.3 +/- 1.8 x 10(-3)/min. The reproducibility and variability of the measurements are discussed. Since the measurements we describe reflect the extent of radical reductions occurring in cell membranes, we suggest that this method can be used to measure the ability to defend oxidants in membranes of erythrocytes with defective antioxidant systems. This method is particularly useful for measuring the modification of the antioxidant system toward radicals in membranes by drugs, chemicals, or environmental toxins.     

类卟啉稀土配合物对于小鼠腹水肝癌细胞光敏损伤的研究

研究了类卟啉稀土配合物（以下简称ＰＬＭ－Ｇｄ－Ａ）对小鼠腹水肝癌细胞（ＡＨ）的光敏作用及ＡＨ细胞对ＰＬＭ－Ｇｄ－Ａ的摄取表明：ＰＬＭ－Ｇｄ－Ａ被ＡＨ细胞摄取的速度快,用ＭＴＴ方法测定了细胞光敏存活曲线,杀伤细胞的能力与光照时间和光照强度以及ＰＬＭ－Ｇｄ的浓度密切相关,用ＦＡＤＵ方法和电镜观察结果证明：该光敏损伤细胞的靶主要是在细胞核;对于不同稀土离子配合物光敏能力比较表明：Ｇｄ＞Ｅｕ＞Ｓｍ;造成细     

用荧光漂白恢复技术研究竹红菌乙素在小鼠肝癌细胞内的扩散过程

利用竹红菌乙素自身的荧光特征,在ＦＰＲ装置上直接测定了乙素在ＡＨ细胞内的侧向扩散系数和荧光漂白的恢复率。实验结果表明乙素在ＡＨ细胞内的扩散系数Ｄ＝３．２×１０＾－９ｃｍ＾２／ｓ＾－１荧光漂白恢复比率Ｒ＝９７．８％,上述实验说明乙素在细胞膜内与生物大分子之间没有形成共价键形式的结合状态。     

ESR measurement of rapid penetration of DMPO and DEPMPO spin traps through lipid bilayer membranes

The passive permeation rates of DMPO and DEPMPO spin traps and their hydroxyl radical adducts through liposomal membranes were measured using ESR spectroscopy. For the spin traps, we measured the time-dependent change in the signal intensity of the OH-adduct, which is formed by a reaction between the penetrated spin trap and hydroxyl radicals produced by the UV-radiolysis of H(2)O(2) inside the liposomes. The hydroxyl radicals produced outside the liposomes were quenched with polyethylene glycol. For the OH-adduct, pre-formed adduct was mixed with liposomes and the time-dependent change of the ESR signal was measured in the presence of a line-broadening reagent outside the liposomes to make the signal outside the liposomes invisible. Both the spin traps and their OH-adducts diffused across the lipid membranes rapidly and reached equilibrium within tens of seconds. These findings suggest that if used for the detection of free radicals inside cells, these spin traps should be well distributed in cells and even in organelles.     

Spin-label studies of membrane-associated denatured hemoglobin in normal and sickle cells

A maleimide spin label (N-(1-oxyl-2,2,5,5-tetramethylpyrrolidinyl)-maleimide) was reacted with oxyhemoglobin-free cell stromata of normal and sickle cells. The EPR spectrum of spin-labeled red cell membranes showed that the spin labels are attached to at least two different binding sites. There was a major signal, A, which characterized a strongly immobilized environment and a minor signal, B, which characterized a weakly immobilized environment. Quantitative EPR measurements using equal amounts of Hb AA and Hb SS red blood cells demonstrated that Hb SS red cell membranes had an approximately four times higher EPR signal intensity than Hb AA red cell membranes ((7.98 ± 1.14) · 10⁵ and (2.2 ± 1.2) · 10⁵ spin labels/cell, respectively). Moreover, the ratio of signal intensities A and B are different in these cells. Comparative spectrophotometric studies of membrane-associated denatured hemoglobins of Hb AA and Hb SS red cell membranes suggested that the EPR signal A is derived from spin labels attached to membrane-associated denatured hemoglobin, while signal B is mainly from spin labels attached to membrane-associated denatured hemoglobin, while signal B is mainly from spin labels attached to membranes. The combination of EPR spectrum of Hb AA membranes pretreated with N-ethyl-maleimide and that of spin-labeled precipitated hemoglobin further strengthened this conclusion.     

Spin-label studies of membrane-associated denatured hemoglobin in normal and sickle cells.

A maleimide spin label (N-(1-oxyl-2,2,5,5-tetramethylpyrrolidinyl)-maleimide) was reacted with oxyhemoglobin-free cell stromata of normal and sickle cells. The EPR spectrum of spin-labeled red cell membranes showed that the spin labels are attached to at least two different binding sites. There was a major signal, A, which characterized a strongly immobilized environment and a minor signal, B, which characterized a weakly immobilized environment. Quantitative EPR measurements using equal amounts of Hb AA and Hb SS red blood cells demonstrated that Hb SS red cell membranes had an approximately four times higher EPR signal intensity than Hb AA red cell membranes ((7.98 +/- 1.14 . 10(5) and (2.2 +/- 1.2) . 10(5) spin labels/cell, respectively). Moreover, the ratio of signal intensities A and B are different in these cells. Comparative spectrophotometric studies of membrane-associated denatured hemoglobins of Hb AA and Hb SS red cell membranes suggested that the EPR signal A is derived from spin labels attached to membrane-associated denatured hemoglobin, while signal B is mainly from spin labels attached to membranes. The combination of EPR spectrum of Hb AA membranes pretreated with N-ethylmaleimide and that of spin-labeled precipitated hemoglobin further strengthened this conclusion.     

Arginase as an inhibitory principle in liver plasma membranes arresting the growth of various mammalian cells in vitro

Plasma membranes prepared from rat livers inhibited the in vitro growth of various mammalian cells including hepatoma cells in a concentration-dependent manner, showing an almost complete arrest of cell growth at 0.1 mg protein/ml. Some of these cells tested, i.e., leukemia (L1210 and P388) and myeloma (P₃-NS-1/1-Ag4-1) cells, were labile in the presence of plasma membranes (losing the viability), and CHO (Chinese hamster ovary) cells became round without detaching from the substratum. The culture medium preincubated with liver plasma membranes no longer supported the growth of hepatoma cells (AH13 and AH66F). However, the ‘conditioned’ medium supplemented with l-arginine, supported the growth of the cells. Moreover, the addition of l-ornithine to the cultures containing plasma membranes markedly reduced the inhibitory effect of plasma membranes. The plasma membrane preparations were found to possess considerable arginase activity. These results seem to indicate the possible involvement of arginase in the inhibition of cell growth by liver plasma membranes.     

HP (2-20) derived from the amino terminal region of helicobacterpylori ribosomal protein L1 exerts its antifungal effects by damaging the plasma membranes of Candida albicans.

The fungicidal effects of the peptide HP (2-20). derived from the N-terminal sequence of Helicobacter pylori ribosomal protein L1 (RPL1). have been investigated. HP (2-20) displays a strong fungicidal activity against various fungi, without haemolytic activity against human erythrocyte cells, and the fungicidal activity is inhibited by Ca2+ and Mg2+ ions. In order to investigate the fungicidal mechanism(s) of HP (2-20). the amount of intracellular trehalose was measured in C. albicans. It was found that the amounts of intracellular trehalose were decreased when HP (2-20) was used. The action of the peptide against fungal cell membranes was further examined by the potassium-release test; HP (2-20) was found to increase the amount of K+ released from the cells. Furthermore, HP (2-20) caused significant morphological changes, as shown by scanning electron microscopy, and by testing the membrane disrupting activity using liposomes (phosphatidyl choline/cholesterol; 10: 1, w/w). Our results suggest that HP (2-20) may exert its antifungal activity by disrupting the structure of cell membranes, via pore formation or direct interaction with the lipid bilayers.     

Cerebroside sulfuric ester (sulfatide) induces oxygen radical generation in guinea-pig leukocytes

Previous studies on experimental allergic encephalomyelitis have shown that a number of leukocytes appear in demyelinating lesions of guinea-pig brain. The present studies showed that cerebroside sulfuric ester (sulfatide), a typical component of myelin membranes, stimulated the oxidative metabolism of guinea-pig neutrophils and macrophages, leading to marked generation of oxygen radicals and light emission. Formation of a spin adduct of 5,5-dimethyl-1-pyrroline N-oxide by leukocytes was dependent on the concentration of sulfatide, and correlated well with the generation of superoxide anion and the intensity of chemiluminescence measured in the absence of luminol. The addition of myelin membranes to the sulfatide-stimulated neutrophils amplified the light emission, suggesting an interaction between myelin membranes and those of leukocytes. Assay of the thiobarbituric acid reaction in the mixture of membranes and cells showed that sulfatide-stimulated cells induced lipid peroxidation in myelin membranes. These results suggest that sulfatide released from demyelinating lesions stimulates leukocytes to release toxic oxygen radicals, which attack myelin membranes, leading to a chain reaction of demyelination.