57 resultados para Laurencia nidifica


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Morphological and molecular studies were carried out on Laurencia oliveirana from the type locality (Arraial do Cabo, Rio de Janeiro, Brazil). This species is easily recognized by its small size, sub-erect habit forming intricate cushion-like tufts and unilateral pectinate branching. The species displays all the typical characters of the genus Laurencia, such as the production of the first pericentral cell underneath the basal cell of the trichoblast, tetrasporangia produced from particular pericentral cells, with the third and fourth pericentral cells becoming fertile, without production of additional pericentral cells, spermatangial branches produced from one of two laterals on the suprabasal cell of trichoblasts, and procarp-bearing segment with five pericentral cells. Details of tetrasporangial plants and development of procarp and male plants are described for the first time for the species. The phylogenetic position of L. oliveirana was inferred by analysis of the chloroplast-encoded rbcL gene sequences from 57 taxa. In all phylogenetic analyses, L. oliveirana grouped with L. caraibica, L. caduciramulosa, L. venusta and L. natalensis, forming a monophyletic clade within the Laurencia sensu stricto. The genetic divergence between L. oliveirana and the molecularly closest species, L. caraiba collected in Brazil, was 2.3%.

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Laurencia brongniartii J.Agardh

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During the course of chemical investigation of marine algae collected from Karachi coast of Arabian Sea, five sterols named as sarangosterol(1), 23-methyl cholesta-5, 25-dien-3ß-ol(2) from Endarachne binghamiae (brown alga), sargasterol(3) from Dictyota indica (brown alga), cholesterol(4) from Laurencia obtusa (red alga) and clerosterol(5) from Codium iyengarii (green alga) have been isolated. Their structures were elucidated with the help of spectroscopic means.

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Eighteen commonly occurring species of marine benthic red algae, i.e., Asparagopsis taxiformis (Delile) Trevisan, Bangia atropurpurea (Roth) C. Agardh, Centroceras clavulatum (C. Agardh) Montagne, Calliblepharis fimbriata (Greville) Kiitzing, Coelarthrum muelleri (Sonder) B¢rgesen, Cottoniella filamentosa (Howe) B¢rgesen, Gracilariafoliifera (Forsskai) B¢rgesen, Halymenia porphyraeformis (B¢rgesen) Parkinson, Hypnea muscifor:mis (Wulfen) Lamouroux, Hypnea valentiae (Turner) Montagne, Laurencia obtusa (Hudson) Lamouroux, Me!anothamnus somalensis Bomet et Falkenberg, Porphyra vietnamensis Tanaka et Pham-hoang H6, Sarconema filiforme (Sonder) Kylin, Sebdenia flabellata (J. Agardh) Parkinson, Scinaia fascicularis (B¢rgesen) Huisman, Scinaia hatei B¢rgesen, and Solieria robusta (Greville) Kylin were collected from coastal areas near Karachi (Pakistan) and taxonomically investigated. All the investigated seaweeds are taxonomically known species. During this study, Melanothamnus somalensis is reported for the first time from northern Arabian Sea and Asparagopsis taxiformis, Bangia atropurpurea, Cottoniella filamentosa, Gracilaria foliifera, Halymenia porphyraeformis, Melanothamnus somalensis, Sarconema filiforme, Sebdenia flabellata, Scinaia fascicularis, and Solieria robusta are taxonomically described for the first time from the coast of Pakistan.

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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.

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凹顶藻属(Laurencia)海藻在分类学上属于红藻门(Rhodophyta)、红藻纲(Rhodophyceae)、仙菜目(Ceramiales)、松节藻科(Rhodomalaceae),主要分布于热带、亚热带和温带海域的低潮线附近及深海部分,约135种,中国有20种以上。凹顶藻次级代谢产物的结构类型主要包括倍半萜、二萜、三萜/聚醚和C15-多聚乙酰等,冈村凹顶藻中,倍半萜和C15-多聚乙酰最为常见,且以卤代著称。本文对凹顶藻卤代机制的研究进行了总结,并对最近10年来从凹顶藻中分离到的倍半萜、C15-多聚乙酰类成分及其合成研究进行了综述,同时对采自山东和广东的两种冈村凹顶藻(Laurencia okamurai Yamada)的化学成分进行了比较研究,发现生长在不同地理位置的同种凹顶藻化学成分有很大差异。 干燥并粉碎的冈村凹顶藻(L. okamurai)分别进行有机溶剂提取,粗提物通过硅胶柱层析、凝胶Sephadex LH-20柱层析、反相硅胶柱层析、制备薄层层析等方法分离纯化得单体化合物,利用超导核磁共振、质谱和红外光谱等现代波谱技术鉴定化合物的结构。从上述采自不同地点的冈村凹顶藻中分离鉴定的化合物共计30个,包括新化合物8个,依次是laurenokamurenes A-E (LA1-LA5),laurenokamurin (LA6),laurenokaldehyde (LA7)和isochlorolaurenol (LB1),新天然产物1个 (LA12)和已知化合物21个。其中,采自山东的冈村凹顶藻次级代谢产物结构类型相对复杂多样,从中分离到的化合物包括bisabolane型倍半萜4个,chamigrane型倍半萜5个,laurane型倍半萜6个,C15-多聚乙酰类化合物5个,其他类型化合物1个(见第III页);从采自广东的冈村凹顶藻中分离鉴定的化合物主要为7个laurane型倍半萜和2个其他类型的化合物(见第IV页)。 对分离鉴定的部分单体化合物进行了抗细菌(金黄色葡萄球菌)活性筛选,结果表明所有的测试样品都不具有抗金黄色葡萄球菌活性。

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本论文对民间药用红树植物木榄(Bruguiera gymnorrhiza)中的次生代谢产物进行了研究,同时还对分离自似瘤凹顶藻(Laurencia similis Namet Saito)的内生真菌EN21(Exophiala oligosperma)进行了化学成分研究。对分离得到的部分化合物进行了初步的DPPH自由基清除活性和抗菌活性筛选。 采用常规的硅胶柱层析、反相硅胶柱层析、制备薄层层析、凝胶Sephadex LH-20 柱层析、半制备型高效液相色谱(HPLC)以及重结晶等手段,从木榄(Bruguiera gymnorrhiza)中分离得到23个化合物;从EN21(Exophiala oligosperma)中分离得到23个化合物。利用一维、二维核磁、质谱、元素分析等各种现代波谱技术及化学反应方法,确定了木榄中20个化合物的结构,包括黄酮单体化合物5个,三萜类化合物11个,甾体化合物2个,长链烷烃2个,其中4个化合物为首次从木榄中报道的黄酮;确定了EN-21中20个化合物的结构,其中脑苷脂1个,甾体化合物7个,芳环化合物3个,三萜类化合物2个,包括1个新天然产物。本文系首次报道Exophiala oligosperma 的化学成分。 对从木榄中分离得到的部分化合物进行了DPPH自由基清除活性筛选, 发现黄酮类化合物BRG-1、BRG-2、BRG-3 、BRG-4显示了较强的DPPH自由基清除活性,而三萜类化合物则未表现出DPPH自由基清除活性。抗菌筛选实验中所有测试样品未显示出活性。 研究结果充实了红树林植物和海藻内生真菌代谢产物的内容,为其有效利用提供了一定的科学依据。

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本论文的研究工作由两部分组成,第一部分研究了海带(Laminaria japonica)水提取物中的活性物质,并研究了提取物对蔬菜促生长的影响及其作用机制。第二部分对三列凹顶藻(Laurencia tristicha)乙醇提取物的乙酸乙酯相进行了活性筛选和化学成分研究,并对其中分离得到的单体化合物进行了生物活性筛选。 第一部分主要以中国人工养殖的海带为原料,使用与海藻多糖生产相结合的提取技术并浓缩其中的有效成分。对浓缩提取物进行了蔬菜的农田效果实验,并对作物抗旱性能的增加、作物硝酸盐积累的减少、作物品质的改善、以及作物抵抗病毒病的能力等影响进行了作用机制方面的研究。海藻浓缩提取物进行的农田效果实验表明:作物抗旱型相对含水量RWC值在92%~94%之间;病毒病的防治效果最高可达到91%;作物的品质有明显的改善,最重要的是首次发现海藻提取物有降低蔬菜中硝酸盐的含量(硝酸盐的含量是与有机蔬菜区别的重要指标之一)的作用。该部分研究工作的创新性主要体现在:(1)首次在国内外提出和采用与海藻多糖生产相结合的提取技术。该技术的应用不但减少了提取成本,使工业化生产成为可能,更重要的是使我国的海藻工业生产可能实现高值化和开辟综合利用的新途径。(2)首次发现海藻中的小分子海藻多糖具有和细胞激动素、甜菜碱、植物生长素等活性物质同样的生物活性。 第二部分的研究是在查阅了大量的近20年来国内外有关红藻凹顶藻中化学成分研究的相关文献的基础上,对凹顶藻中的次生代谢产物进行了综述。该论文主要是通过对红藻三列凹顶藻的95%乙醇提取物的乙酸乙酯相进行化学成分分析和生物活性筛选以期能够发现具有药用前景的活性先导化合物。 为了寻找具有生物活性的化合物,我们对采自我国南海硇洲岛海域的红藻三列凹顶藻的95%乙醇提取物的乙酸乙酯相进行了活性筛选。采用MTT法对其在KB细胞株、Bel-7402细胞株、PC-3M细胞株、MCF-7细胞株、Ketr-3细胞株模型上进行了细胞毒活性测试;采用酶模型对其进行了Na+,K+-ATPase的抑制活性测试;采用MTT法对其在犬主动脉血管模型上进行了血管平滑肌细胞增殖抑制活性测试;结果表明,三列凹顶藻的95%乙醇提取物的乙酸乙酯相对Na+,K+-ATPase和犬血管平滑肌细胞增殖具有一定的抑制活性。 利用正相和反相色谱、Sephadex LH-20色谱以及反相HPLC等手段进行分离纯化,从我国南海海域的红藻三列凹顶藻中分离得到33种化学成分,通过波谱学方法(IR、MS、NMR)以及X-ray单晶衍射试验对其化学结构进行了确证,其中化合物L1~L8为新结构化合物,化合物L5为具有新骨架的全新结构化合物,化合物L9~L13为新天然产物,化合物L18和L22系首次从海洋生物中获得,所有化合物均为首次从该属海藻中得到。新化合物L1~L8均为倍半萜类化合物,命名分别为:(1R,3R)-(-)-3-(3-hydroxy-4-methylphenyl)- 1,3-dimethyl–2-methylidene cyclopentanol (L1), (1R,3R)-(-)-3-(4-methylphenyl)-1,3-dimethyl-2-methylidenecyclopentanol (L2), (1R, 3R)-(-)-3-(2-hydroxy-4-methylphenyl)-1,3-dimethyl–2–methylidenecyclopentanol (L3),(+)-(1S,2R)–2-(3–hydroxy–4–methylphenyl)-1,2-[3.1.0]bicy-clohexane (L4),()-(1S,2R) -5-hydroxy–6–methyl-spiro-dihydrobenzofuran-2(3H),2-{1-methyl-[3.1.0]bicyclohexane} (L5), (+)-6-methyl-2-(p-tolyl)hept-4-en-2,6-diol (L6),(3R,3aS,8bS)-(-)-2,3,3a,8b–tetrahydro–7-bromo – 3 a– hydroxymethyl - 3, 6, 8b - trimethyl-1H- cyclopenta[b] benzofuran (L7 ),(3R, 3aS, 8bS) - (-) - 2,3,3a,8b–tetrahydro–3 a–hydroxymethyl-3,6,8b -trimethyl -1H – cyclopenta [b] benzofuran (L8)。25个已知结构化合物确定为:(+)-(1R,2R)-4-bromo-1,5, 9–trimethyl–12– methylidene–8–oxa-tricyclo[7.2.1.02]dodeca-2,4,6-triene (L9),(3S,3aR,8bS)-(-)-2,3,3a, 8b– tetra -hydro–7-bromo–3–hydroxy-3,3a,6,8b-tetramethyl-1H-cyclopenta[b]benzofu- ran (L10 ),(3R, 3aR, 8bS) - (-) - 2, 3, 3a, 8b – tetrahydro – 7 - bromo – 3 – hydroxy - 3,3a,6,8b - tetramethyl - 1H - cyclopenta [b] benzofuran (L11 ),(3S,3aR,8bS) - (-) - 2, 3, 3a, 8b – tetrahydro –3–hydroxy -3, 3a, 6, 8b - tetramethyl-1H-cyclopenta[b]benzofuran (L12 ), ( 3aR, 8bS) - (-) - 3a,8b –dihydro–7 - bromo – 3, 3a, 6, 8b - tetramethyl - 1H - cyclopenta[b]benzofuran (L13 ),aplysinol (L14 ) ,aplysin (L15),laurebiphenyl (L16),johnstonol (L17),gossonorol (L18),7,10-epoxy-ar- bisabol-11-ol (L19),10-epi-7,10-epoxyarbisabol-11-ol (L20) 3β-hydroxy- 5α, 6α-epoxy- β- ionone (L21 ),3β-hydroxy-5β,6β-epoxy-β-ionone (L22 ),胆甾醇 (L23 ),胆甾-5-烯-3β,7α二醇胆甾-5-烯-3β,7α二醇 (L24),β-谷甾醇 (L25),叶绿醇 (L26 ),玉米黄素 (L27 ),对羟基苯甲醛 (L28 ),3-吲哚甲醛 (L29 ),1-O-十六烷酰基-3-O-β-D-吡喃半乳糖基-丙三醇(L30 ),1-O-十八烷酰基-3-O-β-D-吡喃半乳糖基-丙三醇 (L31 ),丙三醇-1-软脂酸单酯 (L32 ),正十六碳酸 (L33 )。 采用MTT法对其中23个单体化合物在Bel-7402细胞株、BGC-823细胞株、A549细胞株、A2780细胞株、HCT-8细胞株和HELL细胞株模型上进行了细胞毒活性测试;采用MTT法对其中13个单体化合物在犬主动脉血管模型上进行了血管平滑肌细胞增殖抑制活性测试;结果表明,部分单体化合物显示出一定的生物活性。