共查询到20条相似文献,搜索用时 15 毫秒
1.
Formal enantioselective total synthesis of schulzeines A-C was accomplished, featuring highly efficient Pd-catalyzed asymmetric allylic amination using novel diphosphonite ligands (BOPs) to provide 1-vinyltetrahydroisoquinoline key intermediates, as well as Ru-catalyzed ring-closing metathesis reaction to construct the key tricyclic cores in enantiopure form with correct absolute configurations. 相似文献
2.
Three novel C(28)-sterol oligoglucosides, named taccasterosides A-C (1-3), were isolated from the rhizomes of Tacca chantrieri (Taccaceae). Their structures were determined by detailed spectroscopic analysis, including 2D NMR data, and a few chemical transformations. 相似文献
3.
Ratnayake R Lacey E Tennant S Gill JH Capon RJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(5):1610-1619
The kibdelones are a novel family of bioactive heterocyclic polyketides produced by a rare soil actinomycete, Kibdelosporangium sp. (MST-108465). Complete relative stereostructures were assigned to kibdelones A-C (1-3), kibdelone B rhamnoside (5), 13-oxokibdelone A (7), and 25-methoxy-24-oxokibdelone C (8) on the basis of detailed spectroscopic analysis and chemical interconversion, as well as mechanistic and biosynthetic considerations. Under mild conditions, kibdelones B (2) and C (3) undergo a facile equilibration to kibdelones A-C (1-3), while kibdelone B rhamnoside (5) equilibrates to a mixture of kibdelone A-C rhamnosides (4-6). A plausible mechanism for this equilibration is proposed and involves air oxidation, quinone/hydroquinone redox transformations, and a choreographed sequence of keto/enol tautomerizations that aromatize ring C via a quinone methide intermediate. Kibdelones exhibit potent and selective cytotoxicity against a panel of human tumor cell lines and display significant antibacterial and nematocidal activity. 相似文献
4.
Ahmad VU Zubair M Athar Abbasi M Abid Rashid M Rasool N Nahar Khan S Iqbal Choudhary M Kousar F 《Magnetic resonance in chemistry : MRC》2005,43(6):486-488
The investigation of the chemical constituents of Symplocos racemosa Roxb led to the isolation of two new glycosides, symcomoside A (1) and symcomoside B (2), together with one known glycoside, tortoside C (3), which is reported for the first time from this plant. The structures of the new compounds were determined by 1D and 2D homonuclear and heteronuclear NMR spectroscopy, from chemical evidence and by comparison with published data for closely related compounds. Symcomoside B (2) showed potent inhibitory activity against alpha-glucosidase in a concentration-dependent fashion with an IC50 value of 0.733 +/- 0.033 mM whereas symcomoside A (1) showed very weak inhibitory activity against alpha-glucosidase (9.90% in 0.70 mM). 相似文献
5.
Hong Ping HE Yun ZOU Yue Mao SHEN Xiao Yan HAO Guo Yin ZUO Xiao Jiang HAO * Laboratory of Phytochemistry Kunming Institute of Botany Chinese Academy of Sciences Kunming . Department of Medicinal Chemistry Guiyang Medical College 《中国化学快报》2001,(7)
Micromelum integerrimum (Rutaceae) is a shrub growing in Yunnan Province. Leaves and barks of this plant have been used for the treatment of dysentery, and arthritis1. Previous researches revealed that this plant contained coumarins2-8. Micromelin, the main chemical constituent of this plant, showed significant inhibition against leukaemia P-388 cell line (T/C 149% at 10 mg/kg) but was inactive in lower doses, and also showed significant activity (T/C 228% at 1.25 mg/kg) against Lewis lung… 相似文献
6.
Phytochemical study of the stems of Jasminum nudiflorum has led to the isolation of five new secoiridoid glucosides, jasnudiflosides D (1) and E (2) and nudiflosides A-C (3-5). The structures of these compounds were elucidated on the basis of chemical and spectroscopic evidence. 相似文献
7.
Three new caffeoyl galactoic acid derivatives, davidiosides A-C (1-3) together with four known caffeoyl derivatives such as: caffeic acid (4), methyl caffeate (5), chlorogenic acid (6), and methyl chlorogenate (7) were isolated from the leaves of Davidia involucrate. The new structures were determined by spectroscopic data and chemical evidence. 相似文献
8.
Four new alkaloids have been isolated during chemical investigations into a southern Australian marine sponge, Stelletta sp. Detailed spectroscopic analysis, supported by chemical degradation and partial synthesis, permitted structure elucidation of bistellettazines A-C ( 1- 3), the first reported examples of terpenyl-pyrrolizidine conjugates, and bistellettazole A ( 4), a unique cyclic terpenyl-imidazole conjugate. The alkaloids 1- 4 feature unprecedented carbon skeletons that are proposed to share a common convergent biosynthetic origin, arising via the biogenic equivalent of a Diels-Alder addition between two hypothetical polyenyl norsesquiterpene precursors. 相似文献
9.
Matsunami K Takamori I Shinzato T Aramoto M Kondo K Otsuka H Takeda Y 《Chemical & pharmaceutical bulletin》2006,54(10):1403-1407
Four new megastigmane glucosides, named macarangiosides A-D (2-5), together with mallophenol B, lauroside E, methyl brevifolin carboxylate, and hyperin and isoquercitrin as a mixture were isolated from the leaves of Macaranga tanarius (L.) MULL.-ARG. (Euphorbiaceae). Their structures were elucidated by spectroscopic and chemical analyses. Macarangioside A-C (2-4) and mallophenol B were galloylated on glucose moiety and possessed the potent 2,2-diphenyl-picrylhydrazyl (DPPH) radical-scavenging activity. 相似文献
10.
Nguyen HT Tran HQ Nguyen TT Chau VM Bui KA Pham QL Nguyen MC Kim YH 《Chemical & pharmaceutical bulletin》2011,59(11):1417-1420
Ten oleanane-type saponins (1-10), including three new compounds, namely bifinosides A-C (1-3), were isolated from the roots of Panax bipinnatifidus SEEM. Their structures were elucidated on the basis of chemical and spectroscopic methods. 相似文献
11.
Williams PG Miller ED Asolkar RN Jensen PR Fenical W 《The Journal of organic chemistry》2007,72(14):5025-5034
Chemical evaluation of the saline fermentation broth of several strains of the obligate marine actinomycete Salinispora arenicola has led to the identification of three new macrolide polyketides designated arenicolides A-C (1-3). The planar structures, elucidated via spectroscopic and chemical methods, consist of 26-membered polyunsaturated macrolactones containing repeating vicinal hydroxyl methoxyl moieties. The relative and absolute stereochemistries of 1-3 were assigned by a combination of J-based configurational analyses and chemical derivatization. 相似文献
12.
Eucalyptals A-C (1-3) with a new skeleton of 3,5-diformyl-isopentyl phloroglucinol-coupled cadinane were isolated from the fruits of Eucalyptus globulus. Their structures were elucidated by spectroscopic analysis, and that of 1 was confirmed by single-crystal X-ray diffraction. The biosynthetic pathway of 1-3 was also postulated. Compounds 1-3 exhibited selective cytotoxicity against the HL-60 cell line. 相似文献
13.
M R Siro T L?vgren 《Acta chemica Scandinavica. Series B: Organic chemistry and biochemistry》1978,32(6):447-451
An alpha-glucosidase was purified from baker's yeast. The molecular weight was approximately 44 000 daltons. SDS-disc gel electrophoresis suggested that the enzyme consisted of four subunits. The isoelectric point was at pH 5.4. The Km values for p-nitrophenyl alpha-D-glucopyranoside and maltose were 2.9 X 10(-4) and 2.5 X 10(-2) M, respectively. Binding of 2-(p-toluidino)naphthalene-6-sulfonate to the alpha-glucosidase was associated with a strong increase in fluorescence. The dissociation constant of the enzyme-TNS complex was 8 X 10(-5) M. The fluorescent probe did not interfere with the binding of glucose to the enzyme although the alpha-glucosidase was inhibited by high concentrations of TNS. The formation of an enzyme-glucose complex was indicated by an increase of fluorescence and by a shift in the wavelength for maximal emission which suggests that the binding process is associated with a change in conformation. The dissociation constant of the glucose--alpha-glucosidase complex KD = 0.57 X 10(-3) M, was calculated from the increase in fluorescence as a function of glucose concentration. 相似文献
14.
Three new cycloartenol triterpene saponins, named shengmaxinsides A-C, have been isolated from the ethyl acetate soluble fraction of an ethanol extract of Cimicifuga simplex Wormsk roots. Their structures were established by chemical tests and detailed spectroscopic analysis as 25-O-acetyl-7,8-didehydrocimigenol-3-O-β-D-galactopyranoside (1), 7,8-didehydrocimigenol-3-O-β-D-galactopyranoside (2) and 7,8-didehydro-24S-O-acetylhydroshengmanol-3-O-β-D-galactopyranoside (3), respectively. 相似文献
15.
Kijjoa A Santos S Dethoup T Manoch L Almeida AP Vasconcelos MH Silva A Gales L Herz W 《Natural product communications》2011,6(6):807-812
Chemical investigation of a collection of the fungus Neosartorya glabra from Thailand furnished sartoryglabins A-C (1a, 1b and 2) which are analogs of the reverse prenylated indole alkaloids known as (-) ardeemins. Structures of these compounds were established by NMR spectrometry and an X-ray analysis. Sartoryglabins A-C were evaluated for their in vitro growth inhibitory activity on three human tumor cell lines: MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer) and A375-C5 (melanoma). All the compounds exhibited strong to moderate activity against the MCF-7 cell line but weak or no activity against the NCI-H460 and A375-C5 cell lines. Sartoryglabin B was found to exhibit selectivity towards the MCF-7 cell line. 相似文献
16.
Shibano M Tsukamoto D Masuda A Tanaka Y Kusano G 《Chemical & pharmaceutical bulletin》2001,49(10):1362-1365
Two new pyrrolidine alkaloids, radicamines A and B were isolated as inhibitors of alpha-glucosidase from Lobelia chinensis Lour. (Campanulaceae). Radicamines A and B were formulated as (2S,3S,4S,5S)-2-hydroxymethyl-3,4-dihydroxy-5-(3-hydroxy-4-methoxyphenyl)-pyrrolidine (1) and (2S,3S,4S,5S)-2-hydroxymethyl-3,4-dihydroxy-5-(4-hydroxyphenyl)-pyrrolidine (2) on the basis of spectroscopic analyses and chemical methods. 相似文献
17.
Phenylethyl cinnamides as potential alpha-glucosidase inhibitors from the roots of Solanum melongena
Bioassay-guided fractionation against alpha-glucosidase resulted in isolation and identification of six phenolic compounds (1-6) from the 70% EtOH extract of the roots of Solanum melongena L. (Solanaceae). Of these, three phenylethyl cinnamides, N-trans-feruloyl tyramine (1), N-trans-p-coumaroyl tyramine (2) and N-cis-p-coumaroyl tyramine (3) possessed inhibitory activity against alpha-glucosidase with IC50 values of 500.6, 5.3 and 46.3 microM, respectively. Mechanism analysis revealed these phenylethyl cinnamides were non-competitive inhibitors. This is the first study of the alpha-glucosidase inhibitory activities of the roots of S. melongena, and this preliminary observation suggested potential medicinal use of this herb. 相似文献
18.
Shi YM Li XY Li XN Luo X Xue YB Liang CQ Zou J Kong LM Li Y Pu JX Xiao WL Sun HD 《Organic letters》2011,13(15):3848-3851
Schicagenins A-C (1-3), three unprecedented nortriterpenoids characterized with a tetracyclic oxa-cage motif and C(9) side chain, were discovered from the leaves and stems of Schisandra chinensis. Their structures were determined on the basis of extensive spectroscopic analysis, and the absolute stereochemistries were established by single-crystal X-ray diffraction and CD experiments. A plausible biosynthetic pathway of 1-3 was also discussed. 相似文献
19.
A chemoenzymatic asymmetric synthesis of the title compound was developed by a building-block approach. The key steps of the synthesis were (i) an enantioselective lipase-catalyzed acylation of a secondary alcohol, (ii) an efficient diastereoselective addition of an alkyl-lithium reagent to a glyceraldehyde derivative, (iii) conversion of an epoxide to a one-carbon homologated allylic alcohol via a sulphorane addition, and (iv) a cross metathesis between two chiral allylic alcohols and subsequent functionalization to obtain the ethyl ester of the hydroxy acid unit of the schulzeines. 相似文献
20.
Kundu B Rastogi SK Ahmad R Srivastava AK 《Combinatorial chemistry & high throughput screening》2002,5(7):545-550
A library of 72 compounds related to N- [4-(benzyloxy) benzoyl]alanine (I) was synthesized, prepared and screened for alpha-glucosidase inhibitory activity. Four compounds showed potent inhibition, six compounds moderate inhibition, and 16 were weak inhibitors. One compound, N- [4-(benzyloxy) benzoyl] serine, was found to be a potent inhibitor of alpha-glucosidase with 100% inhibition at 1 micro M. This inhibitor was at least five times more potent than the lead compound I. 相似文献