共查询到20条相似文献,搜索用时 15 毫秒
1.
Heloisa A. Guimarães Ivo J. C. Vieira Raimundo Braz‐Filho Antônio E. M. Crotti Vitor S. dos Almeida Renata C. de Paula 《Helvetica chimica acta》2013,96(9):1793-1800
Two novel indole alkaloids with plumeran skeleton, N‐benzoyl‐12‐demethoxycylindrocarine and N‐cinnamoyl‐12‐demethoxycylindrocarine ( 1 and 2 , resp.), were isolated from the MeOH extract of the stem bark of Aspidosperma cylindrocarpon Müll .Arg . These compounds were obtained by high‐speed counter‐current chromatography, and their structures were elucidated on the basis of their NMR (1D and 2D) data. They were tested in vitro against chloroquine‐resistant strains of Plasmodium falciparum, and only 2 showed a weak activity (IC50 127.97 ng/ml with respect to the standard drug). Several other known compounds, comprising steroids, flavonoids, the rarely found atraric acid, as well as the previously reported alkaloid 3 , were also isolated by conventional chromatographic techniques. 相似文献
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The isolation and structure elucidation of a novel alkaloid, namely of the 14‐O‐ethyl‐substituted (3α,14α,16α)‐2,7‐secoeburnamine derivative 1 from the leaf of Melodinus henryi is reported. Ten known alkaloids were also isolated. Their structures were determined spectroscopically. The isolates were evaluated for their cytotoxicity. 相似文献
4.
Farooq U Khan A Ahmad VU;Azhar-Ul-Haq Khan SS Farooq R Pervez A Shah MM 《Magnetic resonance in chemistry : MRC》2007,45(9):766-769
Two new tricyclic trans-clerodane diterpenoids trivially named as ballotenic acid A (1) and ballodiolic acid A (2) have been isolated from ethyl acetate fraction of Otostegia limbata. The structure assignments are based on (1)H and (13)C NMR spectra, 2D NMR (HMQC, HMBC, COSY, NOESY and NOE) techniques and comparison with the literature data. 相似文献
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Using modern NMR techniques, including DQF-COSY, NOESY, HETCOR and HMBC, the full assignments of all 1H and 13C chemical shifts were made for stigmastane-3,6-dione and stigmast-4-ene-3,6-dione, isolated from the roots of Piper nigrum (Piperaceae). Their stereochemistry was resolved by a combination of 2D NOESY data and analysis of coupling constants. The two compounds were isolated from the genus Piper for the first time. 相似文献
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In this work we describe the complete (1)H and (13)C NMR analyses of three arylnaphtalene lignan lactones (taiwanin C, 4-methyl dehydroretrodendrin and justicidin B) using modern NMR techniques such as gCOSY, nonedited gHSQC, gHMBC and NOE experiments. Complete assignment and homonuclear hydrogen coupling constant measurements were performed. 相似文献
7.
《Magnetic resonance in chemistry : MRC》2003,41(7):545-548
2,3,8,9,10,11‐Hexahydro‐7H‐dibenzo[de,h]quinolin‐7‐one, 5‐methoxy‐2,3,8,9,10,11‐hexahydro‐7H‐dibenzo[de,h]quinolin‐7‐one, 5‐methoxy‐6‐hydroxy‐1,2,3,7a,8,9,10,11,11a,11b‐decahydro‐7H‐dibenzo[de,h]quinolin‐7‐one, 5‐methoxy‐5,6,8,9,10,11‐hexahydro‐4H‐dibenzo[de,h]quinolin‐7‐ol, 5,6,8,9,10,11‐hexahydro‐4H‐dibenzo[de,h]quinolin‐7‐ol and 5,6‐dihydro‐4H‐dibenzo[de,h]quinolin‐7‐ol were prepared by catalytic hydrogenation of oxoisoaporphines or their 2,3‐dihydro derivatives over PtO2 in acetic acid under mild conditions. Their structures were confirmed and 1H and 13C NMR spectra were completely assigned using a combination of one‐ and two‐dimensional NMR techniques. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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Na Z Cho JY Lee HJ Chung JH Park KD Lee YJ Shin SC Rim YS Park KH Moon JH 《Magnetic resonance in chemistry : MRC》2007,45(3):275-278
Four sesquiterpene glucosides were isolated from Ixeris sonchifolia Hance. The structure of a new compound (1) was assigned as 9beta-monohydroxy-2,12-dioxo-guaia-3,11(13)-dien-1alpha,5alpha,6beta,7alpha,9beta,10alphaH-12,6-olide-9-O-beta-D- glucopyranoside (ixerinoside). In addition, unambiguous and complete assignments of (1)H NMR chemical shifts for crepidiaside A (2), ixerin Z (3), and 11,13alpha-dihydroixerin Z (4) are presented. The assignments were achieved by two-dimensional NMR (gCOSY, gHSQC, gHMBC, NOESY) and one-dimensional nuclear Overhauser effect (NOE) experiments. 相似文献
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Sobarzo-Sánchez E De la Fuente J Quezada E Castedo L 《Magnetic resonance in chemistry : MRC》2006,44(12):1131-1134
The anabaseine derivatives 6-methoxy-7-hydroxy-1-(pyridin-3-yl)-3,4-dihydroisoquinoline, 6,7-dimethoxy-1-(pyridin-3-yl)-1,2,3,4-tetrahydroisoquinoline and 6,7-dimethoxy-1-(piperidin-3-yl)-1,2,3,4-tetrahydroisoquino- line were prepared either by demethylation with HBr or by reduction with different reagents, NaBH4 and H2/PtO2 from 6,7-dimethoxy-1-(pyridin-3-yl)-3,4-dihydroisoquinoline, as starting material. The structures have been fully assigned by the combination of one- and two-dimensional experiments. 相似文献
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Complete NMR analyses with full assignments for (1)H and (13)C NMR spectral data for both epimers of menthane-1-carboxylic acid are described. The NMR properties of the recently synthesized axial isomer had not been previously described, and through use of a variety of 1D and 2D techniques, additional information is provided for the equatorial isomer. As well as assignments of chemical shifts, homonuclear coupling constants were determined for the equatorial isomer and most of coupling constants were measured for the axial isomer. 相似文献
11.
《Magnetic resonance in chemistry : MRC》2003,41(4):283-286
The complete analyses of the 1H and 13C NMR spectra of the ortho ester analogues of etoposide are reported and differentiation of the α and β isomers of these derivatives is suggested by using the γ‐gauche effect upon the 13C chemical shift. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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Two new guaianolides, 8alpha-hydroxy-11alpha,13-dihydroglucozaluzanin C and 11alpha,13-dihydroglucozaluzanin C, were isolated from Ainsliaea fragrans, along with two known guaianolides, 8alpha-hydroxy-11alpha,13-dihydrozaluzanin C and glucozaluzanin C. The structures of the new compounds were unambiguously established by HR-ESI-MS, one-dimensional (1D) (DEPT), two-dimensional (2D) ((1)H-(1)H COSY, HSQC, HMBC, ROESY) NMR experiments and by comparison with structurally related compounds. The known compounds were identified by comparison of spectral data with published references. Some NMR data of the known compounds were reported for the first time. 相似文献
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Abstract Lipid A exhibits thp most important biological attributes of lipopolysaccharide (LPS) of gram-negative bacteria including endotoxicity, adjuvanticity and antitu-mor activity.′ The lipid A backbone, in general, is found to consist of a pyranosidic β 1,6-linked D-glucosamine disaccharide [β-D-GlcpN-(1→6)-α-D-GlcpN] phospho-rylated at 1 and 4′ positions and bearing two amide bound and two ester linked hydroxy and/or acyloxy fatty acids.2 However, the lipid A moiety of LPS from var-ious strains of the two gram-negative, photosynthetic bacteria, Rhodopseudomonas virtdia and Rhodopseudomonas palustrts, possesses 2,3-diamino-2,3-dideoxy-D-glucose as a constituent sugar. 3 This diamino sugar has been also reported to occur in LPS from several other bacterial specie4.5 Recently we found that the lipid X of Brucella abortus contains p(1→6)-linked 2,3-diamino-2,3-dideoxy-D- glucopyranose disaccharide moiety with a phosphate group at the 4′ position and amide bound acyloxy and hydroxy fatty acids.6 相似文献
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Six flavone derivatives were studied. Previously reported NMR data of three of these derivatives were corrected and the NMR data for the other three derivatives not studied previously were completely assigned on the basis of the basic 1D and 2D NMR experiments and molecular modeling. 相似文献
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本文报道了环状聚芳酯低聚物的核磁共振碳谱及氢谱。测定了其碳及氢的自旋晶格驰豫时间,通过与类似物质标准谱图的比较、自旋晶格驰豫时间的分析以及化学位移取代基效应的计算等,归属了其碳氢谱峰。 相似文献
17.
Skorić I Marinić Z Molcanov K Kojić-Prodić B Sindler-Kulyk M 《Magnetic resonance in chemistry : MRC》2007,45(8):680-684
1H and 13C NMR spectra of trans, trans-2,3-divinylfuran derivatives (1-4) in CDCl3 were fully assigned using one- and two-dimensional NMR techniques. The 1H NMR resonances of ethylenic protons in position 2 with regard to the corresponding protons in position 3 of the furan ring are discussed. 相似文献
18.
Li‐Rong Sun Jian Yan Lu Lu Sheng‐Ji Pei Zhong‐Rong Li Lin Zhou Xian‐Min Zhang Ming‐Hua Qiu 《Helvetica chimica acta》2007,90(7):1313-1318
Cimicifine A ( 1 ), the first cycloartane triterpene alkaloid, was isolated from the rhizomes of Cimicifuga foetida, together with the known compound cimicifugoside H‐1 ( 2 ). Their chemical structures were established by extensive NMR and MS analyses and by comparison with literature. 相似文献
19.
《Magnetic resonance in chemistry : MRC》2003,41(3):206-212
Unambiguous and complete assignments of 1H and 13C NMR chemical shifts for 15 limonoids, eight of them found in natural sources and seven other synthetic derivatives, are presented. The assignments are based on 2D shift‐correlated [1H,1H‐COSY, 1H,13C‐gHSQC‐1J(C,H), 1H,13C‐gHMBC‐nJ(C,H) (n = 2 and 3)] and NOE experiments. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
20.
Xiaoyan Xie Jinhe Jiang Ying Liu Kang Min Yongmei Xue Bi Jing Yan Zhang Yegao Chen 《Helvetica chimica acta》2010,93(7):1381-1384
A new lycopodine alkaloid, 15α‐methyllycopodane‐5β,6β‐diol N‐oxide ( 1 ), was isolated from the whole plants of Phlegmariurus yunnanensis Ching , together with the two known alkaloids 15α‐methyllycopodane‐5β,6β‐diol ( 2 ) and lycoposerramine H ( 3 ), and four serratene‐type triterpenoids, serratenediol‐3‐acetate ( 4 ), serratenediol ( 5 ), lycocryptol ( 6 ), and serratriol ( 7 ). Their structures were elucidated on the basis of spectroscopic analyses, including HR‐ESI‐MS, 1H‐ and 13C‐NMR, DEPT, 1H,1H‐COSY, HSQC, HMBC, and NOESY. 相似文献