Al-Fadhli Ammar, Wahidulla Solimabi, D'Souza Lisette
National Institute of Oceanography, Dona Paula, Goa 403 004, India.
Glycobiology. 2006 Oct;16(10):902-15. doi: 10.1093/glycob/cwl018. Epub 2006 Jun 24.
Three distinct fractions containing polar glycolipids (PF(1-3)) were isolated from the chloroform soluble fraction of crude methanolic extract of red alga Chondria armata (Kütz.) Okamura on gel chromatography over Sephadex LH20. Their structure was elucidated by multidimensional nuclear magnetic resonance (NMR) techniques like 1H, 1H correlation spectroscopy (COSY), 1H, 1H total COSY (TOCSY), 1H, 13C heteronuclear multiple quantum coherence (HMQC), and 1H, 13C heteronuclear multiple bond correlation (HMBC) complemented by electrospray ionization mass spectrometry (ESI-MS) in the positive ion mode. The coupling constant of the anomeric proton in 1H NMR spectrum and sign of rotation indicated an exclusive configuration of the sugar molecules in the glycerolipids. Major glycolipids were identified as (2R)-2-O-(5,8,11,14-eicosatetranoyl)-3-O-alpha-d-galactopyranosyl-sn-glycerol (GL2), its pentacetate (GL1), and (2R)-1-O-(palmitoyl)-2-O-(5,8,11, 14,17-eicosapentanoyl)-3-O-beta-d-galactopyranosyl-sn-glycerol (GL3). Each was methanolysed to give the same galactosylglycerol which on ESI-MS provided a pseudomolecular ion at m/z 309 representing deacylated glycolipid with the sodiated sugar moiety. Additionally, six minor glycolipids were also identified on the basis of ESI-MS. These include a 1,2-di-O-acyl-3-O-(acyl-6'-galactosyl)-glycerol (GL1a), sulfonoglycolipids 2-O-palmitoyl-3-O-(6'-sulfoquinovopyranosyl)-glycerol (GL2a) and its ethyl ether derivative (GL2b), 1-oleoyl-2-palmitoyl-3-O-galactosyl glycerol (GL3a), and 1,2-diacyl phosphatidyl glycerol (GL3b). GL1, GL1a, and GL2b are new to the literature. The novelty of the remaining identified compounds lies in the diversity of their fatty acid composition. Antimicrobial properties of these glycolipids against pathogens were evaluated. The yeast Candida albicans and the bacteria Klebsiella sp. were as sensitive as the standard Nystatin and antibiotic Streptomycin against PF3. Considerable activity was expressed by the same metabolite against the fungus Cryptococcus neoformans as compared to the control. Weak activity against the bacteria Shigella flexineri and Vibrio cholerae and the fungus Aspergillus fumigatus was also observed. Fraction PF2 was weakly active against some strains whereas all of them were resistant to its acetyl derivative PF1. Antimicrobial activity of glycolipids is being reported here for the first time.
从红藻冈村软骨藻（Chondria armata (Kütz.) Okamura）粗甲醇提取物的氯仿可溶部分，通过在葡聚糖凝胶LH20上进行凝胶色谱法，分离出了三种含有极性糖脂的不同馏分（PF(1 - 3)）。它们的结构通过多维核磁共振（NMR）技术得以阐明，如1H、1H相关光谱法（COSY）、1H、1H全相关光谱法（TOCSY）、1H、13C异核多量子相干（HMQC）以及1H、13C异核多键相关（HMBC），并辅以正离子模式下的电喷雾电离质谱（ESI - MS）。1H NMR光谱中异头质子的耦合常数以及旋光符号表明了糖脂中糖分子的独特构型。主要的糖脂被鉴定为(2R)-2 - O-(5,8,11,14 - 二十碳四烯酰基)-3 - O-α - d - 吡喃半乳糖基 - sn - 甘油（GL2）、其五乙酸酯（GL1）以及(2R)-1 - O-(棕榈酰基)-2 - O-(5,8,11,14,17 - 二十碳五烯酰基)-3 - O-β - d - 吡喃半乳糖基 - sn - 甘油（GL3）。每种糖脂经甲醇解后得到相同的半乳糖基甘油，其在ESI - MS上产生一个质荷比为309的准分子离子，代表去酰化糖脂与钠化糖部分。此外，还基于ESI - MS鉴定出了六种次要的糖脂。这些包括1,2 - 二 - O - 酰基 - 3 - O-(酰基 - 6'-半乳糖基)-甘油（GL1a）、磺基糖脂2 - O - 棕榈酰基 - 3 - O-(6'-磺基喹诺吡喃糖基)-甘油（GL2a）及其乙醚衍生物（GL2b）、1 - 油酰基 - 2 - 棕榈酰基 - 3 - O - 半乳糖基甘油（GL3a）以及1,2 - 二酰基磷脂酰甘油（GL3b）。GL1、GL1a和GL2b在文献中是首次报道。其余鉴定出的化合物的新颖之处在于其脂肪酸组成的多样性。评估了这些糖脂对病原体的抗菌特性。白色念珠菌酵母和克雷伯氏菌属细菌对PF3的敏感性与标准制霉菌素和抗生素链霉素相当。与对照相比，该代谢物对新型隐球菌真菌表现出相当强的活性。还观察到对弗氏志贺氏菌和霍乱弧菌细菌以及烟曲霉真菌的活性较弱。馏分PF2对某些菌株有微弱活性，而所有菌株对其乙酰衍生物PF1均有抗性。本文首次报道了糖脂的抗菌活性。
