New triterpene saponins, foliatheasaponins I-V, were isolated from the methanolic extract of Tencha [the leaves of Camellia sinensis (L.) O. KUNTZE (Theaceae)]. The chemical structures of these new saponins were elucidated on the basis of chemical and physicochemical evidence. Among the new saponins, foliatheasaponins II and III, were found to inhibit release of beta-hexosaminidase, as a marker of antigen-induced degranulation, in RBL-2H3 cells. 相似文献
A series of thieno [2,3-?]-, [3,2-?]- and [3,4-?]morphans prepared both by the Grewe synthesis and by the reaction of 2-cyanopyridines with 3-thienyllithium is described. Furthermore, a new synthetic route to thieno [2,3-?] morphans from 3-ketotetrahydrolhiophene is reported. Separation and assignment of the α- and β-diastereomerie structures by means of nmr data is reported. Some side products were isolated and their structures were confirmed on the basis of their spectral data. Mechanisms for their formation are proposed. 相似文献
A new and highly versatile method for the synthesis of 1, 3, 4-thiadiazol-2 (3 H)ones 1 is described. Methoxy-1,3,4-thiadiazoles- 5 , which are readily available by condensation of O-methyl thiocarbazate ( 2 ) with acid derivatives 3 , undergo an efficient cleavage to 1 and methyl chloride with hydrochloric acid in an anhydrous medium. Many new 5-substituted thiadiazolones, unavailable by earlier routes, were synthesized. Preparative as well as mechanistic aspects are discussed. With the aid of 13C-NMR. spectroscopy, the tautomerism of 1 was studied, and the tautomeric equilibria was shown to be dependent on the nature of the substituent in the 5-position. The thiadiazolones 1 exist predominantly in the oxo form. The percentage of the hydroxy form, however, increases with strongly electron withdrawing substituents in the 5-position. A good correlation with pKa? and σ-values was observed. 相似文献
A new [(2-oxo-l,3-cyclopentanediylidene)bis(methylidyne-p-phenyleneoxy)]diacetic acid dihydrazide III has been prepared via interaction of 2,5-bis(p-hydroxybenzylidene) cyclopentanone I with ethyl chloroacetate in basic medium to give diester II, followed by hydrazinolysis with hydrazine. The synthesized compounds were confirmed by IR, NMR, and elemental analyses. Unreported poly-hydrazides by the low temperature interfacial polycondensation technique of III with adipoyl, sebacoyl, 4,4′-diphenic, isophthaloyl, terephthaloyl, 4,4′-azodibenzoyl, 3,3′-azodibenzoyl, 4,4′[1,4-phenylene-bis(methylidynenitrilo)]dibenzoyl dichlorides, and 2,7-dichloroformylthianthrene-5,5′,10,10′-teraoxide were prepared. In order to characterize the polymers, a model compound was synthesized from III and benzoyl chloride. The resulting polyhydrazides were confirmed by IR, UV, viscometry, DSC measurements, and thermogravimetric analysis. The crystallinities of all polyhydrazides were investigated by x-ray analysis. The effect of the nature of different moieties on the properties of these polyhydrazides was explored by comparing their physical, spectral, thermal, and x-ray analysis data. 相似文献
Six new triterpenoid glycosides called julibrosides A1-A4, B1 and C1 were isolated from Albizziae Cortex, the dried stem bark of Albizzia julibrissin Durazz. Their structures were determined based on spectral and chemical evidence. Julibrosides B1 and C1 had new sapogenols, designated julibrogenin B and C, respectively, while julibrosides A3 included N-acetyl-D-glucosamine as a sugar component. 相似文献
The saponin fraction from the fresh leaves of Euiptelea polyandra Sieb. et Zucc. was found to exhibit potent gastroprotective activity. Fourteen new nortriterpene saponins called eupteleasaponins were isolated from the saponin fraction with gastroprotective activity. The structures of eupteleasaponins I, I1, III, IV, V, and V acetate were determined on the basis of chemical and physicochemical evidence as 3-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranosyl(1 -->3)-beta-D-xylopyranosylakebonoic acid 28-O-beta-D-glucopyranosyl ester, 3-O-alpha-L-rhamnopyranosyl(1-->2)-[alpha-L-rhamnopyranosyl(1 -->4)-beta-D-glucopyranosyl(1-->3)-beta-D-xylopyranosylakebonoic acid 28-O-beta-D- D-glucopyranosyl(1-->3)-beta-D-xylopyranosylakebonoic acid 28-O-beta-D-glucopyranosyl ester, 3-O-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-rhamnopyranosyl(1 -->4)-beta-D-glucopyranosyl(1-->3)-beta-D-xylopyranosylakebonoic acid 28-O-beta-D-glucopyranosyl ester, 3-O-alpha-L-rhamnopyranosyl(1 -->2)-[alpha-L-arabinopyranosyl(1-->4)-alpha-L-rhamnopyranosyl(1-- >4)]-beta-D- glucopyranosyl(1-->3)-beta-D-xylopyranosylakebonoic acid 28-O-beta-D-glucopyranosyl ester, 3-O-alpha-L-rhamnopyranosvl(1-->2)-[alpha-L-arabinopyranosyl (1 -->4)-beta-L-rhamnopyranosyl(1 -->4)]-beta-D-glucopyranosyl(1 -->3)-beta-D-xylopyranosylakebonoic acid, 3-O-alpha-L-rhamnopyranosyl(1 -->2)-beta-D-glucopyranosvl(1-->3)-beta-D-xylopyranosyleupteleo genin, and 3-O-alpha-L-rhamnopyranosyl(1-->2)-6"-O-acetyl-gamma-D-glucopyranosyl(1 -->3)-beta-D-xylopyranosyleupteleogenin. 相似文献
Two acylated oleanane-type triterpene oligoglycosides, chakasaponins V and VI, an aromatic glycoside, chakanoside I, and an acylated flavonol oligoglycoside, chakaflavonoside A, were isolated from the flower buds of Chinese tea plant [Camellia sinensis (L.) O. KUNTZE]. The chemical structures of those new glycosides were elucidated on the basis of chemical and physicochemical evidence. 相似文献
A new triterpene glycoside — medicoside H — has been isolated from the roots ofMedicago sativa L. (Fabaceae), and on the basis of chemical transformations and spectral characteristics its structure has been established
as medicagenic acid 3-O-β-D-glucopyranoside 28-O-[O-α-L-rhamnopyronosyl-(1 → 2)-β-L-arabino-pyranoside].
Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh
Soedinenii, No. 5, pp. 673–677, September–October, 1989. 相似文献
This review article summarizes the findings of recent typing studies conducted on Vibrio cholerae, V. parahaemolyticus, and V. vulnificus. The DNA-based methods used to type the Vibrio spp. include whole genome approaches, such as pulsed field gel electrophoresis (PFGE), ribotyping, and repetitive extragenic palindromic (REP)-PCR, single gene targets, and multiple gene targets (multilocus approaches). The goals of these studies include establishing the relatedness of isolates from disease epidemics, discriminating among strains with more or less potential to cause disease or epidemics, and exploring the population biology of these waterborne pathogens. PFGE was consistently among the more discriminatory of the typing methods for all three Vibrio spp., and was useful for tracing the temporal and geographic relatedness of epidemic strains of V. cholerae and V. parahaemolyticus. However, PFGE did not group V. vulnificus strains according to the genotypes that have been proposed as markers of virulence potential. Typing methods that target repetitive elements distributed throughout the genome, such as BOX-PCR and REP-PCR, and DNA sequence-based methods, such as multilocus sequence typing, were also highly discriminatory and, in some cases, superior to PFGE for phylogenetic analysis and identification of strains with high epidemic or virulence potential. As typing methods and strategies are refined and used, the epidemiology, virulence potential, and ecology of these pathogenic Vibrio spp. will become better understood. 相似文献
?I chose chemistry as a career because it gives me the opportunity to discover and make new things every day. When I wake up I use Skype to catch up with my son Stepan (who is currently finishing his PhD at MSU), since this time of day is the best compromise for our busy schedules given the 10 hour time‐zone difference between Colorado and Moscow…?.“ This and more about Olga V. Boltalina can be found on page 2827.
Twelve new furylorganylsilanes and furfurylorganylsilanes are synthesized by reacting 2-furyllithium, 5-methyl-2-furyllithium, and 5-trimethylsilyl-2-furyllithium with organylchlorosilanes, organylchlorohydrosilanes, chloromethyltriorganylsilanes, and silicon tetrachloride.-(2-furyl)ethyltrimethylsilane and 1-furyl-2-trimethylsilylethanol-1, which were previously unknown, are synthesized by reacting trimethylsilylmethyl magnesium chloride with furfuryl chloride and furfural, respectively.For Part IV see [1]. 相似文献
The new alkaloid komarovicine has been isolated from the epigeal part of the plantNitraria komarovii Iljin et Lava. Its structure has been established on the basis of spectral and experimental results and its synthesis has been performed. A transition has been made to the alkaloids komarovine and komarovidine isolated previously. 相似文献
Abstract A new bromometric assay procedure for penicillins was developed, using an organic brominating agent. 1,3-Dibromo, 5,5-dimethylhydantion (DBH). The experimental conditions, the molar ratio as well as the identification of the reaction products were thoroughly studied. The end point could be detected visually or potentiometrically. Spectrophotometric titration could also be performed. The suggested procedure could be successfully applied to pharmaceutical preparations containing penicillins. The percentage recoveries for different penicillins were satisfactory. 相似文献
ESR spectra of purified and ferric ion-sensitized celluloses irradiated with ultraviolet light in vacuo at 45, 20, ?80, and ?196°C were recoreded and compared. Generally, several kinds of spectra, viz., singlet, three-line, five-line, and seven-line spectra, were observed. At higher temperatures, only singlet and three-line spectra of stable free-radical species were detected, whereas at lower temperatures such as at ?196°C, two doubled spectra of formyl radicals and hydrogen atoms were also detected in addition to cellulose radicals. It is believed that the intricate spectra observed at low temperatures are superimposed upon spectra generated by free radicals which may or may not be stable at high temperatures. During reirradiation at ?196°C with an alternative light sources, i.e., λ > 2537 Å and λ > 3400 Å, of samples which were irradiated at 20°C or at ?196°C, phenomena indicative of radical transformation and formation of new radicals or of decay of radicals in terms of ultraviolet bleaching were observed on studying the changes of line-shapes and relative signal intensities of the spectra. 相似文献
A new indole alkaloid, 11-hydroxypolyneuridine, was isolated from Vinca major subsp. major L. and the known indole alkaloids vallesiachotamine and isovallesiachotamine from Vinca minor L. This is the first report on the alkaloids of both Vinca species growing in Turkey; vallesiachotamine and isovallesiachotamine were isolated from a Vinca species for the first time. V. minor may be considered as a new source for these two alkaloids due to their occurrence in high amount in the aerial parts of the plant. The alkaloid extracts of the two Vinca species were found to have high lipid peroxidation inhibitory and DPPH radical scavenging activities. Anticholinesterase activity of the extracts was also very strong. 相似文献
One new cycloartane triterpenoid, named markhacanasin C (1), together with three known triterpenoids, oleanolic acid (2), ursolic acid (3) and 6β,19α-dihydroxyursolic acid (4) were isolated by various chromatographic methods from the most cytotoxic fraction of the ethyl acetate extract of Markhamia stipulata var. canaense V.S. Dang leaves. Among them, 4 was reported for the first time from the genus Markhamia, while 2 and 3 were found for the first time from this species. Their structures were elucidated by IR, UV, HR-ESI-MS and NMR experiments. The cytotoxicity of isolated compounds (3 and 4) against three human cancer cell lines (HeLa, HepG2, and MCF-7) were evaluated. At the concentration of 100 μg/mL, 3 exhibited significant cytotoxic activity (86.36 ± 3.69%). 相似文献
The vibrational spectra of the following compounds were measured: X+AlMe−4; X+GaMe−4 and X+InMe−4 (with X = Na, K, Me4P+, Me4As+ or Me4Sb+). For the purpose of comparison the spectra of compounds of group IV and V elements were taken from the literature or measured a second time. With a new procedure for determination of force-constants a set of comparable force-constants for the tetramethyl compounds of the elements Al, Si, P/Ga, Ge, As/In, Sn, Sb was obtained. 相似文献
The laser-induced fluorescence technique is applied to study vibrational energy transfer in pure ONF. Different vibrational modes are excited using a TEA CO2 laser and the rise and fall of ν1, ν2, and (ν1 + ν3) fluorescence is detected. These measurements yield a detailed picture of V—V exchange in the region of the fundamentals and V—R,T transfer to rotational and translational degrees of freedom. The relaxation behavior of ONF is compared with that of ONCI and other triatomic molecules. 相似文献
Four innovations added to the V.I. Vernadsky’s concepts on the biosphere in recent author’s publications were summarized. These innovations are as follows: (a) a new typology of the matter in the biosphere; (b) modernization of the concept of the biogenic migration of chemical elements; (c) a new, fourth, biogeochemical principle; and (d) a more detailed presentation of the concept of a substantial influence of organisms on physical and chemical parameters of the biosphere: namely, the development of a new theory of the multifunctional role of the biota in water self-purification in the hydrosphere. 相似文献
AbstractFrom the leaves of Markhamia stipulata var. canaense V.S. Dang, one new phytosphingolipid, named markhasphingolipid A (6) together with five known compounds, 4’,7-O-dimethylapigenin (1), narigenin (2), tectoquinone (3), mollic acid (4), 1-hexadecanoyl-sn-glycerol (5) were classified by various chromatographic methods. Their structures were designated by IR, UV, HR-ESI-MS, HR-ESI-MS/MS and NMR experiments. All compounds were recognized for the first time from this species. The cytotoxicity of all n-hexane fractions and isolated compounds (5 & 6) against three human cancer cell lines (HeLa, HepG2, and MCF-7) were evaluated by SRB assay. All n-hexane fractions expressed cytotoxic effect on three tested cancer cell lines (at the concentration of 100?μg/mL, percent of cytotoxicity ranged from 55.81% to 95.83%) as well as compound 5 (IC50 ranged from 48.51 to 63.30?μM) whereas fraction H.I and compound 6 did not show activity. 相似文献