3种念珠藻多糖对自由基的清除作用

研究了地木耳(Nostoc commune)、葛仙米(N.sphaeroides)和发菜(N.flagelliform e)3种念珠藻多糖对自由基的清除作用。结果表明,3种念珠藻多糖对超氧阴离子自由基和羟自由基具有很强的清除作用,且呈量效关系,地木耳清除超氧自由基作用最强,最高清除率达72.3%,葛仙米和发菜分别为46.7%、35.5%;发菜清除羟自由基效果最强,最高清除率达74.3%,葛仙米和地木耳清除率分别为49.0%、46.7%;3种念珠藻多糖对DPPH自由基的清除作用不显著。

人参及其有效成份水杨酸与麦芽醇对生物膜的抗氧化作用和机理的研究

红参根乙醇提取物的乙醇溶液或在一定浓度范围内能明显地抑制氢氧自由基导致的人工膜卵磷脂脂质体过氧化，作为红参中的有效成份水杨酸和麦芽醇也表现出对人工膜卵磷脂脂质本的强抗氧化作用。水杨酸乙醇溶液在室温23 ℃下防止脂质体的过氧化作用随浓度增加而增加，在37℃下存在-最适抗氧化浓度。水杨酸水溶液的抗氧化作用在室温23 ℃下也随其浓度增加而增加。麦芽醇水溶液在室温23 ℃下存在-最适抗氧化浓度。水杨酸，麦芽醇水溶液对天然膜红细胞膜也具有保护作用，它们均能明显地抑制过氧化氢导致的红细胞溶血。培养莱氏衣原体，分离提纯了莱氏衣原体膜磷脂和糖脂。用脂肪酸甲酯化方法分析莱氏衣原体膜磷脂脂质体和蛋黄卵磷脂脂质体中各种脂肪酸链含量随脂质体氧化而变化的情况，发现最短饱和脂肪酸链最易被氧化，当脂质体中加入水杨酸或麦芽醇时，最长不饱和脂肪酸链受到保护，说明在强氧化条件下生物膜脂双层中的饱和脂肪酸也可被氧化。这就对生物膜的氧化机理有了更深入的了解。在电子自旋共振实验中观察到水杨酸使DPPH（一种稳定的自由基）的自旋共振信号逐渐减弱，表明水杨酸具有猝灭自由基的作用。水杨酸与氢氧息由基的反应产物经质谱分析（EI质谱法、CI质谱法、高分辨质谱法），其结构为2，3-二羧基苯甲酸和2.5-二羧基苯甲酸麦芽醇与OH的反应产物经高压液相色谱分离制备得两个产物，其结构有待进一步分析。因此，水杨酸麦芽醇及红参乙醇提取物对生物膜表现出的抗氢氧自由基氧化作用得到解释。

高浓度CO2、O3对蒙古栎和华山松次生代谢的影响

本文以蒙古栎和华山松为对象，通过开顶箱法研究了在连续一年高浓度CO2（700 μmol•mol-1）、O3（80 nmol•mol-1）及二者复合处理条件下蒙古栎和华山松的次生代谢动态变化情况，阐明了高浓度CO2、O3对蒙古栎、华山松次生代谢的影响，为研究城市森林对全球变化的响应与反馈，城市森林适宜树种选择提供了重要理论依据。 得出的主要结果如下： 1． 高浓度CO2处理提高了蒙古栎叶片苯丙氨酸解氨酶（PAL）、多酚氧化酶（PPO）两种酶活性且于生长季末期达差异显著，对蒙古栎（过氧化物酶）POD活性无显著影响；对华山松松针中PAL、PPO两种酶活性无显著影响，于生长季末显著提高了华山松POD活性。 2． 高浓度CO2处理增加了蒙古栎叶片中总酚、单宁、类黄酮、木质素和纤维素含量，并于生长季的不同时期达到差异显著，其中木质素和纤维素在生长季初期曾显著减少；显著增加了华山松松针中单宁和纤维素含量、显著减少了总酚和类黄酮含量，对木质素无显著影响。 3． 高浓度O3处理显著提高了蒙古栎叶片PAL、PPO两种酶活性，对蒙古栎POD活性无显著影响；显著提高了华山松松针中PAL和POD（于生长季中期曾显著降低）活性，降低了PPO活性。 4． 高浓度O3处理于生长季初期显著增加了蒙古栎叶片中总酚含量，于生长季末显著减少了类黄酮含量，于生长季初期显著增加末期显著减少了单宁含量，显著增加了木质素和纤维素含量；显著减少了华山松松针中总酚、单宁和类黄酮含量，对木质素含量无显著影响，于生长季初期显著增加后期显著减少纤维素含量。 5． 复合处理于生长季末期显著降低了蒙古栎叶片PAL活性，于生长季中期显著提高了POD活性，于生长季中期显著降低了华山松松针中PPO和POD活性。 6． 复合处理显著增加了蒙古栎叶片总酚和木质素含量，先显著增加后显著减少了单宁含量，先显著减少后显著增加了纤维素含量；先显著减少后显著增加了华山松松针中总酚、单宁和木质素含量，先显著增加后显著减少了纤维素含量，显著减少了类黄酮含量。 7． 使用DPPH法对蒙古栎叶片醇提物进行了总抗氧化能力的测定，结果表明高浓度CO2和O3及其复合处理均显著提高了蒙古栎总的抗氧化能力，但是不同处理分别于生长季的不同阶段达到差异显著水平。

高浓度臭氧对蒙古栎叶片酚类物质含量和总抗氧化能力的影响

采用开顶箱(OTC)法,研究了高浓度臭氧(80±8nmol·mol-1)熏蒸处理对蒙古栎叶片中总酚、类黄酮、单宁及丙二醛(MDA)含量的影响,使用1,1-二苯基苦基苯肼(DPPH)法测定了蒙古栎叶片的总抗氧化能力.结果表明:蒙古栎叶片中总酚、类黄酮、缩合单宁和MDA的含量都有所增加,其中总酚和缩合单宁含量分别增加了48.17%和26.77%,差异显著(P<0.05);类黄酮和MDA含量分别增加了24.66%和5.26%,差异不显著(P>0.05);蒙古栎叶片总抗氧化能力显著增强(P<0.05),且与叶片中总酚和缩合单宁含量呈显著的正相关关系.

山杏种皮黑色素的抗氧化活性

对山杏种皮黑色素的抗氧化活性进行评价。结果表明:山杏种皮黑色素可以显著抑制β-胡萝卜素的氧化褪色,其清除自由基活性具有量效性,清除羟自由基能力与2,6-二叔丁基对甲酚(BHT)无显著差异而高于抗坏血酸(VC),清除超氧阴离子能力超过BHT和VC。山杏种皮黑色素既可以作为氢供体,清除DPPH自由基,但清除能力低于BHT和VC,也可作为电子供体,其还原能力高于BHT和VC。

Effects of ultrahigh pressure extraction conditions on yields and antioxidant activity of ginsenoside from ginseng

Ultrahigh pressure technique was employed to extract ginsenosides from roots of ginseng (Panax ginseng C.A. Meyer). The optimal conditions for ultrahigh pressure extraction (UPE) of total ginsenosides were quantified by UV-vis spectrophotometry with the ginsenoside Re as standard, the signal ginsenosides were quantified by HPLC and ELSD with ginsenosides Re, Rg(1), Rb-1, Rc and Rb-2 as standards. Orthogonal design was applied to evaluate the effects of four independent factors (extraction pressure, extraction temperature, extraction time and ethanol concentration) on the yield and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of ginsenoside, which are based on microwave extraction (ME), ultrasound extraction (UE), soxhlet extraction (SE) and heat reflux extraction (HRE) method. The results showed that UPE method can produce ginsenoside with the highest yield and the best radical scavenging activity compared to other used ones. Scanning electron microscopic (SEM) images of the plant cells after ultrahigh pressure treatment was obtained to provide visual evidence of the disruption effect.

辉光放电中处理聚四氟乙烯表面——Ⅱ.ESR研究PTFE膜自由基

在外部电极电容耦合式反应装置中,对聚四氟乙烯(PTFE)膜进行了辉光放电处理。通过电子自旋共振(ESR)谱研究了PTFE在处理过程中所产生的自由基,着重讨论了温度对ESR谱的影响。最后,以DPPH为内标,测定了处理后PTFE膜的自由基浓度,并考察了自由基在空气中的衰减情况。

Highly brominated mono- and bis-phenols from the marine red alga Symphyocladia latiuscula with radical-scavenging activity

Four new highly brominated and fully substituted mono- and bis-phenols, 1-(2,3,6-tribromo-4,5-dihydroxybenzyl)pyrrolidin-2-one (1), 1,2-bis(2,3,6-tribromo-4,5-dihydroxyphenyl)ethane (2), 6-(2,3,6-tribromo-4,5-dihydroxybenzyl)-2,5-dibromo-3,4-dihydroxybenzyl methyl ether (3), and 2,3,6-tribromo-4,5-dihydroxybenzyl methyl sulfone (4), were characterized from the marine red alga Symphyocladia latiuscula. In addition, five known bromophenols, bis(2,3,6-tribromo-4,5-dihydroxyphenyl)methane (5), bis(2,3,6-tribromo-4,5-dihydroxybenzyl) ether (6), 2,3,6-tribromo-4,5-dihydroxybenzyl methyl ether (7), 2,3,6-tribromo-4,5-dihydroxymethylbenzene (8), and 2,3,6-tribromo-4,5-dihydroxybenzaldehyde (9), were also isolated and identified. The structures of these compounds were elucidated by spectroscopic methods including 1D and 2D NMR as well as by low- and high-resolution mass spectrometric analysis. Structurally, all of these compounds are highly brominated and fully substituted, and contain one or two 2,3,6-tribromo-4,5-dihydroxyphenyl unit(s) in each of the molecules. In addition, compound 4 possesses a unique sulfone structural feature. Each of the isolated compounds was evaluated for alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical-scavenging activity and all were found to be potent, with IC50 values ranging from 8.1 to 24.7 mu M, compared to the known positive control butylated hydroxytoluene (BHT), with an IC50 of 81.8 mu M.

Urceolatin, a structurally unique bromophenol from Polysiphonia urceolata

6-Bromo-1-(3-bromo-4,5-dihydroxybenzyl)phenanthro[4,5-bcd]furan-2,3,5-triol (urceolatin, 1), a highly oxygenated bromophenol containing an unprecedented naturally occurring benzylphenanthro[4,5-bcd]furan unit, was isolated from the marine red alga Polysiphonia urceolata. Its structure was established on the basis of extensive spectroscopic analysis. Compound 1 displayed significant DPPH radical-scavenging activity with an IC50 value of 7.9 mu M, which is 10-fold more potent than that of the positive control, butylated hydroxytoluene.

Chaetopyranin, a benzaldehyde derivative, and other related metabolites from Chaetomium globosum, an endophytic fungus derived from the marine red alga Polysiphonia urceolata

Cultivation of the endophytic fungus Chaetomium globosum, which was isolated from the inner tissue of the marine red alga Polysiphonia urceolata, resulted in the isolation of chaetopyranin (1), a new benzaldehyde secondary metabolite. Ten known compounds were also isolated, including two benzaldehyde congeners, 2-(2 ',3-epoxy-1 ',3 '-heptadienyl)-6-hydroxy- 5-(3-methyl-2-butenyl) benzaldehyde (2) and isotetrahydroauroglaucin (3), two anthraquinone derivatives, erythroglaucin (4) and parietin (5), five asperentin derivatives including asperentin ( 6, also known as cladosporin), 5 '-hydroxy-asperentin-8-methylether (7), asperentin-8-methyl ether (8), 4 '-hydroxyasperentin (9), and 5 '-hydroxyasperentin (10), and the prenylated diketopiperazine congener neoechinulin A (11). The structures of these compounds were determined on the basis of their spectroscopic data analysis (H-1, C-13, H-1-H-1 COSY, HMQC, and HMBC NMR, as well as low- and high-resolution mass experiments). To our knowledge, compound 1 represents the first example of a 2H-benzopyran derivative of marine algal-derived fungi as well as of the fungal genus Chaetomium. Each isolate was tested for its DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging property. Compounds 1-4 were found to have moderate activity. Chaetopyranin (1) also exhibited moderate to weak cytotoxic activity toward several tumor cell lines.

Benzodiazepine Alkaloids from Marine-Derived Endophytic Fungus Aspergillus ochraceus

A new fungus-derived benzodiazepine analogue, 2-hydroxycircumdatin C (1), and a compound which has been isolated from a natural resource for the first time, but has been previously synthesized, namely (11aS)-2,3-dihydro-7-methoxy-1H-pyrrolo[2,1-c][1,4]benzodiazepine-5,11(10H,11aH)-dione (2), along with five structurally related known alkaloids (3-7), were isolated from Aspergillus ochraceus, an endophytic fungus derived from the marine brown alga Sargassum kjellmanianum. Their structures were established on the basis of spectroscopic methods. The absolute configuration of I was determined through CD evidence. Compound 1 displayed significant DPPH radical-scavenging activity with an IC50 value of 9.9 mu M, which is 8.9-fold more potent than that of butylated hydroxytoluene (BHT), a well-known synthetic positive control.

In vitro antioxidative activities of extract and semi-purified fractions of the marine red alga, Rhodomela confervoides (Rhodomelaceae)

The methanol-chloroform extract of the marine red alga, Rhodomela confervoides, was measured for antioxidant activity, using the alpha,alpha-diphenyl-beta-picrylhydrazyl radical-scavenging assay and the beta-carotene-linoleate bleaching assay systems, and compared with those of the positive Controls of butylated hydroxytoluene, gallic acid and ascorbic acid, The active extract was further purified by liquid-liquid partition to afford four fractions, of which the ethyl acetate-soluble (EA) fraction exhibited the strongest antioxidant activity in both assay systems. This fraction was further divided into seven subfractions, designated as EA1-EA7, by silica gel vacuum liquid chromatography. in most cases, EA1 and EM Were found to possess the strongest activity. The total phenolic contents and reducing powers of the extract, fractions, and subfractions were also determined. Significant associations between the antioxidant potency and the total phenolic content, as well as between the antioxidant potency and the reducing power, were found for the tested fractions and subfractions. (c) 2008 Elsevier Ltd. All rights reserved.

Evaluation of 28 marine algae from the Qingdao coast for antioxidative capacity and determination of antioxidant efficiency and total phenolic content of fractions and subfractions derived from Symphyocladia latiuscula (Rhodomelaceae)

The extracts obtained from 28 species of marine algae were evaluated for their antioxidant activity (AA) versus the positive controls butylated hydroxytoluene (BHT), gallic acid (GA), and ascorbic acid (AscA). Most of the tested samples displayed antioxidant activity to various degrees. Among them, the extract of Symphyocladia latiuscula exhibited the strongest AA, which was comparable to BHT, GA, and AscA in radical scavenging activity, as shown in the DPPH (alpha,alpha-diphenyl-beta-picrylhydrazyl) assay, and higher than those of the positive controls in beta-carotene-linoleate assay system. In addition, the ethyl acetate-soluble fraction isolated from the crude extract of S. latiuscula exhibited the highest antioxidant activity in both assay systems. This fraction was further fractionated into seven subfractions (F1-F7) by vacuum liquid chromatography (VLC). F1 and F4 were found to be the most effective subfractions in scavenging DPPH radical assay and in the beta-carotene-linoleate assay, respectively. The total phenolic content (TPC) and reducing power (RP) for all of the extracts, fractions, and subfractions (F1-F7) were also determined. The TPC of the 28 extracts ranged from 0.10 to 8.00 gallic acid equivalents (mg/g seaweed dry weight) while the RP ranged from 0.07 to 11.60 ascorbic acid equivalents (mg center dot g(-1) seaweed dry weight). Highly positive relationships between AA and TPC as well as between AA and RP were found for the extracts and fractions, while for the subfractions F1-F7 only weak or no such relations were found. The results obtained from this study indicate that further analysis is needed of those marine algal species that contain the most antioxidant activity in order to identify the active principles.

Evaluation of antioxidant property of extract and fractions obtained from a red alga, Polysiphonia urceolata

Antioxidant activity (AA), total phenolic content, and reducing power of the crude extract, fractions, and subfractions derived from a red alga, Polysiphonia urceolata, were evaluated and determined. The antioxidative activity was measured using the alpha,alpha-diphenyl-beta-pierylhydrazyl (DPPH) radical scavenging assay and the P-carotene-linoleate assay systems, and compared with that of butylated hydroxytoluene (BHT), gallic acid (GA), and ascorbic acid (AscA). The results showed that the crude extract and the ethyl acetate-soluble fraction exhibited higher AA than BHT in the DPPH assay model, at all of four concentration levels tested (from 0.4 to 50 mu g/ml), while, in the beta-carotene-linoleate assay system, the crude extract and the ethyl acetate-soluble fraction exhibited similar or, in most cases, higher AA than GA and AscA at the same concentrations (from 10 to 200 mu g/ml). The ethyl acetate-soluble fraction was further fractionated into seven subfractions F1-F7 by silica gel vacuum liquid chromatography. F1 was found to be the most effective subfraction in both assay systems. The total phenolic content and reducing power were determined using the Folin-Ciocalteu and the potassium ferricyanide reduction methods, respectively. Statistical analysis indicated a significant association between the antioxidant potency and total phenolic content as well as between the antioxidant potency and reducing power. (c) 2005 Elsevier Ltd. All rights reserved.

Dioxopiperazine Alkaloids Produced by the Marine Mangrove Derived Endophytic Fungus Eurotium rubrum

Cultivation of the fungal strain Eurotium rubrum, an endophytic fungus that was isolated from the inner tissue of stems of the mangrove plant Hibiscus tiliaceus, resulted in the isolation of two new dioxopiperazine derivatives, namely, dehydrovariecolorin L (1) and dehydroechinulin (2), together with eight known dioxopiperazine compounds including variecolorin L (3), echinulin (4), isoechinulin A (5), dihydroxyisoechinulin A (6), preechinulin (7), neoechinulin A (8), neoechinulin E (9), and cryptoechinuline D (10). The structures of the isolated compounds were determined by extensive analysis of their spectroscopic data as well as by comparison with literature. Compounds 1, 2, 9, and 10 were investigated for their a,a-diphenyl-beta-picrylhydrazyl (DPPH) radical-scavenging activity. In addition, the new compounds, 1 and 2, were evaluated for their cytotoxic activity against the P-388, HL-60, and A549 cell lines.