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21.
为了研究藏药臭蚤草的浩性成分,我们利用各种柱色谱技术,从藏药臭蚤草甲醇提取物的乙酸乙酯萃取相分离到4个化合物,通过1D、2DNMR、MS和HRMS等试验,鉴定为2,4-dihydroxy-6-methyl—ethanone-4-O-β-D—Glc(1),4-(3’-hydroxypropyl)-2,6-dimethoxyphenol-3’-O-β-D—glcoside(2),4-allyl-2-methoxyphenol-1-O-β-gleo—side(3),2-methyl-1,3,6-trihydroxy-9,10-anthraquinone-3—O-(6'-O-Ac)-α—L—Rha-(1→2)-β-D—Gle(4),其中化合物1—3为苯丙素苷类化合物,化合物4为蒽醌苷。化合物1—4都是首次从该属植物中分离得到,化合物1为新的苯丙素苷类化合物。 相似文献
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从多穗金粟兰(Chloranthus multistachys)全株的甲醇提取物中分离得到1个新的酚苷,通过波谱技术鉴定其结构为丁香酸-4-O-a-L-鼠李吡喃糖苷(1).同时还首次从该植物中分离得到两个已知倍半萜内酯和一个已知木脂素:1β,4β-二羟基-5a,8β-二氢-7(11)Z-桉叶烯-8,12-内酯(2),lβ,4a-二羟基-5a,8β-二氢-7(11)Z-桉叶烯-8,12-内酯(3),(-)-(7S,8R)-dihydrodehydrodiconifery alcohol(4). 相似文献
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Three iridoid glycosides 6-O-(3'-O-benzoyl)-alpha-l-rhamnopyranosylcatalpol (1a), 6-O-(3'-O-trans-cinnamoyl)-alpha-l-rhamnopyranosylcatalpol (2a) and 6-O-(3'-O-cis-cinnamoyl)-alpha-l-rhamnopyranosylcatalpol (3a) were isolated from aerial parts of Gmelina arborea and structures were elucidated by spectral analysis. Additionally a known iridoid 6-O-(3', 4'-O-dibenzoyl)-alpha-l-rhamnopyranosylcatalpol (4) was also isolated and identified. 相似文献
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鞭檐犁头尖中的苯丙素甙类化合物 总被引:2,自引:0,他引:2
黄平 《天然产物研究与开发》2004,16(5):403-405
从天南星科植物鞭檐犁头尖的根茎中分离得到3个化合物,运用波谱技术(UV,IR,^1HNMR,^13C NMR and 2D NMR)对它们的化学结构进行解析,分别鉴定为松柏甙(1),甲基松柏甙(2)和硝酸钾(3)。从鞭檐犁头尖中分离得到苯丙素甙类化合物尚属首次。 相似文献
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Takashi Fujita Hitoshi Hatamoto Mari Miyamoto Taisuke Iwasaki Shin-ichi Takafuji 《Biotechnology letters》1998,20(11):1057-1061
Cell suspensions derived from Acer nikoense callus, not containing (S)-rhododendrol, converted 4-(p-hydroxyphenyl)-2- butanone into (R)-, (S)-rhododendrol and their glycosides. (R)- and (S)-rhododendrol formed was only detected in the culture medium and their glycosides only in the cells. The former compound disappeared within a short time and the latter one also tended to decrease during prolonged culture. Quantitative analysis of rhododendrol glycosides in the callus showed that most of them were (S)-rhododendrol 2-O--D-glucopyranoside and its content was much lower than that of the original plants. © Rapid Science Ltd. 1998 相似文献
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CPF_2247 from Clostridium perfringens ATCC 13124 was identified as a putative carbohydrate‐active enzyme by its low sequence identity to endo‐β‐1,4‐glucanases belonging to family 8 of the glycoside hydrolase classification. The X‐ray crystal structure of CPF_2247 determined to 2.0 Å resolution by single‐wavelength anomalous dispersion using seleno‐methionine‐substituted protein revealed an (α/α)6 barrel fold. A large cleft on the surface of the protein contains residues that are structurally conserved with key elements of the catalytic machinery in clan GH‐M glycoside hydrolases. Assessment of CPF_2247 as a carbohydrate‐active enzyme disclosed α‐glucanase activity on amylose, glycogen, and malto‐oligosaccharides. Proteins 2011;. © 2011 Wiley‐Liss, Inc. 相似文献
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Aims: To characterize the duel activities of a glycosyl hydrolase family 3 β‐glucosidase/xylosidase from rumen bacterial metagenome and to investigate the capabilities of its β‐d ‐xylosidase activities for saccharification of hemicellulosic xylans. Methods and Results: A β‐glucosidase/xylosidase gene RuBGX1 was cloned from yak (Bos grunniens) rumen using the metagenomic technology. Recombinant RuBGX1, expressed in Escherichia coli, demonstrated high hydrolytic activities on both p‐nitrophenyl‐β‐d ‐glucopyranoside (pNP‐Glc) and p‐nitrophenyl‐β‐d ‐xylopyranoside (pNP‐Xyl) substrates. Analysis of the kinetic properties indicated that RuBGX1 had a lower affinity for pNP‐Glc substrate as the Km was 0·164 mmol l?1 for pNP‐Glc and 0·03 mmol l?1 for pNP‐Xyl at pH 6·0 and 50°C, respectively. The capabilities of RuBGX1 β‐xylosidase for hydrolysis of xylooligosaccharide substrates were further investigated using an endoxylanase‐coupled assay. Hydrolysis time courses illustrated that a significant increase (about 50%) in the reducing sugars, including xylobiose, xylotriose and xylotetraose, was achieved by supplementing endoxylanase with RuBGX1. Enzymatic product analysis using high‐performance anion‐exchange chromatography‐pulsed amperometric detection showed that RuBGX1 could release xyloses from intermediate xylooligosaccharides produced by endoxylanase. Conclusions: The RuBGX1 shows β‐glucosidase activity in hydrolysis of cello‐oligosaccharides; meanwhile, it has β‐xylosidase activity and functions synergistically with endoxylanase to promote the degradation of hemicellulosic xylans. Significance and Impact of the study: This was the first to report the β‐xylosidase activity of family 3 β‐glucosidase/xylosidase functioned in the degradation of hemicellulosic xylans. The bifunctional β‐glucosidase/xylosidase property of RuBGX1 can be used in simultaneous saccharification of cellulose and xylan into fermentable glucose and xylose. 相似文献
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