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Chemical Constituents (chemical + constituent)
Selected AbstractsDistribution of Chemical Constituents in Superimposed Ice from Austre Brøggerbreen, SpitsbergenGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 1 2000H. Motoyama 10 m and 2.3 m ice cores were obtained on Austre Brøggerbreen, Spitsbergen in Svalbard (78°53,N, 11°56,E, 450 m a.s.l.) in September 1994 and in March 1995, respectively. Stratigraphy, bulk density, pH, electrical conductivity, and major ions were obtained from the core samples. The chemical effect of meltwater percolation through snow/ice is examined. Good correlation between Cl, and Na+ was obtained. The ratio of Cl, to Na+ was 1.14 which was nearly the same value as in bulk sea water. However, the variation of Cl,/Na+ shows that higher ratio occured in the bubble-free ice. Furthermore the Cl, ions remain in higher concentration than SO 4 2, or Na+ ions. [source] New Chemical Constituents from Borreria verticillata (Rubiaceae)HELVETICA CHIMICA ACTA, Issue 9 2010Vinicius F. Moreira Abstract A phytochemical study on Borreria verticillata has led to the isolation of two novel simple indole alkaloids, 6-methoxy-4-(3-methylbut-2-en-1-yl)-1H -indole, named verticillatine A (1), and 1-(1H -indol-6-yl)-3-methylbutan-1-one, named verticillatine B (2), one new iridoid, 6,- O -(2-glyceryl)scandoside methyl ester (3), with the glycerol unit linked to a glucose unit, and two known ones, asperuloside (4) and scandoside methyl ester (5). The structures of these compounds were elucidated on the basis of spectroscopic-data analyses, mainly 1H- and 13C-NMR, including 2D experiments (1H,1H-COSY, NOESY, HMBC, and HMQC), and HR-ESI-MS. [source] Chemical Constituents of Polyalthia nemoralisHELVETICA CHIMICA ACTA, Issue 4 2007Xiu-Feng He Abstract Three new natural products, the taraxastane-type triterpenoid 1, the azafluorene-based constituent 2-hydroxyonychine (2), and the diterpenoid nemoralisin (3) were isolated from the EtOH extract of Polyalthia nemoralis, along with five known compounds. The structures of the new compounds were established by in-depth spectroscopic and mass-spectrometric analyses, as well as by chemical transformation. [source] Chemical Constituents from the Fruits of Madhuca latifoliaHELVETICA CHIMICA ACTA, Issue 5 2004From the fruit coats of the medicinal plant Madhuca latifolia were isolated three new compounds, the triterpenoid madhucic acid (=3,- (octanoyloxy)-11-oxoolean-12-en-28-oic acid; 1), the untypical isoflavone madhushazone (=9-methoxy-7-(2,3,6-trimethoxyphenyl)-[1,3]dioxolo[4,5- g][1]benzopyran-8(8H)-one; 2), and a bis(isoflavone) named madhusalmone (=5,14-dimethoxy-3,12-bis(3,4,5-trimethoxyphenyl)-1,6,8,10,15,17-hexaoxanaphtho[2,,3,:,6,7]cyclodeca[1,2- b]naphthalene-4,13(4H,13H)-dione; 3), as well as eight known constituents, and their structures were elucidated by spectral analysis, including 2D-NMR techniques. [source] Bioactive Chemical Constituents of Cladiella SpeciesHELVETICA CHIMICA ACTA, Issue 3 2004Athar Ata From the methanolic extract of Cladiella sp., collected from the Andaman Island, India, a new sesquiterpene, cladidiol (2), and three known diterpenes, cladiellaperoxide (3), (6E)-2,,9, -epoxyeunicella-6,11(12)-dien-3, -ol (4), and polyanthellin A (5) were isolated. The structures of these compounds were established by extensive spectroscopic studies. Compound 2 exhibited modest acetylcholinesterase-inhibition activity, and compounds 3,5 showed antibacterial activities against Streptococcus pyogenes, Escherichia coli, and Pseudomonas aeruginosa. [source] Chemical Constituents of the Roots of Piper sarmentosum.CHEMINFORM, Issue 29 2006Pittaya Tuntiwachwuttikul Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Chemical Constituents from the Roots of Schnabelia tetradonta.CHEMINFORM, Issue 52 2003Hui Dou Abstract For Abstract see ChemInform Abstract in Full Text. [source] Chemical Constituents of Diospyros nigraCHEMINFORM, Issue 7 2003B. Dinda Abstract For Abstract see ChemInform Abstract in Full Text. [source] Chemical Constituents of Plants from the Genus NeriumCHEMISTRY & BIODIVERSITY, Issue 5 2010Pallavi Sharma First page of article [source] Chemical Constituents of Plants from the Genus XylocarpusCHEMISTRY & BIODIVERSITY, Issue 9 2009Li-Ru Shen First page of article [source] Chemical Constituents of Plants from the Genus IlliciumCHEMISTRY & BIODIVERSITY, Issue 7 2009Yun-Ning Liu First page of article [source] Chemical Constituents of the Plants of the Genus CalophyllumCHEMISTRY & BIODIVERSITY, Issue 12 2008Xiao-Hui Su First page of article [source] Study of Antimalarial Activity of Chemical Constituents from Diospyros quaesitaCHEMISTRY & BIODIVERSITY, Issue 11 2008Cui-Ying Ma Abstract Bioassay-directed fractionation led to the isolation of seven compounds from a sample of the dried leaves, twigs, and branches of Diospyros quaesitaThw. (Ebenaceae). One of the isolates, betulinic acid 3-caffeate (1), showed in vitro antimalarial activity against Plasmodium falciparum clones D6 (chloroquine-sensitive) and W2 (chloroquine-resistant) with IC50 values of 1.40 and 0.98,,M, respectively. Evaluation of compound 1 in the human oral epidermoid (KB) cancer cell line revealed cytotoxicity at ED50 of 4.0,,M. In an attempt to reduce the cytotoxicity of 1, the acetylated derivative 1a and betulinic acid (1b) were prepared. Of the seven isolates, diospyrosin (2) was determined to be a new neolignan. In addition to 1, other known compounds isolated in this study were pinoresinol, lariciresinol, N -benzoyl- L -phenylalaninol, scopoletin, and poriferast-5-en-3,,7, -diol. The structure of 2 was elucidated based on spectroscopic data analysis including 1D- and 2D-NMR, and HR-ESI-MS. [source] Chemical Constituents and Bioactivities of Plants of ChloranthaceaeCHEMISTRY & BIODIVERSITY, Issue 2 2008Cong-Mei Cao First page of article [source] Structures and Biological Properties of the Chemical Constituents from the Genus WedeliaCHEMISTRY & BIODIVERSITY, Issue 5 2007Xing Li First page of article [source] Chemical Constituents of the Plants from the Genus LaggeraCHEMISTRY & BIODIVERSITY, Issue 2 2007Xing-Cui Li First page of article [source] Chemical Constituents of Plants from the Genus SymplocosCHEMISTRY & BIODIVERSITY, Issue 1 2007Chang-Hong Huo Abstract The chemical constituents of Symplocos genus were reviewed with 90 structures and 28 references cited. These constituents include triterpenoids, flavonoids, lignans, phenols, steroids, alkaloids, and iridoids. Triterpenoids are the dominant constituents within the genus Symplocos, some of them exhibited antiproliferative effects. Some phenolic glycoside derivatives showed inhibitory activity against snake-venom phosphodiesterase I and human nucleotide pyrophosphatase phosphodiesterase. [source] Isolation and Enzyme-Inhibition Studies of the Chemical Constituents from Ajuga bracteosaCHEMISTRY & BIODIVERSITY, Issue 1 2007Naheed Riaz Abstract Bractin A (=(2S,3S,4R,5E)-2-{[(2R)-2-hydroxydodecanoyl]amino}triacont-5-ene-1,3,4-triol; 1) and bractin B (=(2S,3S,4R,5E,8E)-2-{[(2R) - 2-hydroxyhexacosanoyl]amino}pentadeca-5,8-diene-3,4,15-triol 1- O - , - D -glucopyranoside; 2), new sphingolipids, and bractic acid (=(5Z,10Z,15Z)-2-decyl-4,7,8,12,13,17,18-heptahydroxy-20,23-dioxopentacosa-5,10,15-trienoic acid; 3), a long-chain polyhydroxy acid, were isolated from the whole plant Ajuga bracteosa along with four known diterpenoids 4,7. Their structures were deduced by spectral studies including 1D- and 2D-NMR spectroscopy. Compounds 1,3 displayed inhibitory potential against enzyme lipoxygenase, while compounds 4,7 inhibited cholinesterase enzymes in a concentration-dependent manner with IC50 values in the range 10.0,33.0, 14.0,35.2, and 10.0,19.0,,M for lipoxygenase, acetylcholinesterase, and butyrylcholinesterase, respectively. Lineweaver,Burk, and Dixon plots, and their secondary replots indicated that all compounds exhibit non-competitive type of inhibition with Ki values in the range of 9.5,35.2, 15.2,36.0, and 11.6,20.5,,M, for lipoxygenase, acetylcholinesterase, and butyrylcholinesterase, respectively. [source] Chemical Constituents of the Plants in the Genus AchilleaCHEMISTRY & BIODIVERSITY, Issue 11 2006Xiao-Tang Si First page of article [source] Chemical Constituents of Plants from the Genus InulaCHEMISTRY & BIODIVERSITY, Issue 4 2006Yong-Ming Zhao First page of article [source] Chemical constituents and antimicrobial activities of the essential oil of Acroptilon repens (L.) DCFLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2006Hassan Norouzi-Arasi Abstract The volatile oil from the aerial parts of Acroptilon repens (L.) DC. (Russian knapweed) growing wild in Iran was investigated by GC and GC,MS. Twenty-two components, representing 84.0% of the oil, were identified. The main constituents of the oil were caryophyllene oxide (36.6%), , -copaene (15.6%), , -caryophylene (10.0%) and , -copaene-4- , -ol (5.0%). In addition, the oil was assayed against six Gram-positive and Gram-negative bacteria by measuring the growth inhibitory zone. The oil of A. repens inhibited the growth of Gram-positive bacteria. Staphylococcus saprophyticus and Staphylococcus epidermidis showed strong inhibition zones, while Staphylococcus aureus showed a lower inhibition. The Gram-negative bacteria were insensitive to the oil. Copyright © 2005 John Wiley & Sons, Ltd. [source] Chemical constituents of the essential oil of Asarum forbesii Maxim (Aristolochiaceae)FLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2005Feng Zhang Abstract The essential oils from the leaves and roots of Asarum forbesii Maxim (Aristolochiaceae) were obtained by hydrodistillation and analysed by GC and GC,MS; 20 and 17 constituents were identi,ed from the leaf and root oils, respectively. Methylisoeugenol (33.3%) and , -asarone (19.2%) were the main constituents in the leaf oil, while , -asarone (58.8%) and methyleugenol (10.3%) were the major constituents in the root oil. Copyright © 2004 John Wiley & Sons, Ltd. [source] Chemical constituents of the essential oils of Goniothalamus malayanus Hook. f. and Thoms.FLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2002Ibrahim bin Jantan Abstract The chemical composition of the leaf, bark and root oils of Goniothalamus malayanus Hook. f. and Thoms. was examined by capillary GC and GC,MS. The leaf oil was made up mainly of sesquiterpenoids, of which ,-selinene (33.6%) was the dominant component. The other major compounds present were viridiflorol (13.1%), epi -globulol (7.7%), (E)-nerolidol (4.4%) and globulol (3.8%). The bark and root oils, which were qualitatively similar but with some variation in levels of the individual constituents, were also rich in sesquiterpenoids (97% and 95%, respectively), with eudesmols as the most abundant compounds. The bark oil contained a higher amount of ,-eudesmol (32.2%), ,-eudesmol (21.8%) and ,-eudesmol (6.6%) than the root oil. Copyright © 2002 John Wiley & Sons, Ltd. [source] Chemical constituents and antimicrobial activity of medicinal plants from Ghana: Cassia sieberiana, Haematostaphis barteri, Mitragyna inermis and Pseudocedrela kotschyiPHYTOTHERAPY RESEARCH, Issue 8 2008Alex Asase Abstract The antimicrobial activity of the sequential n -hexane, acetone and 50% aqueous methanol extracts of leaves, stem bark and roots of four species of medicinal plants, Cassia sieberiana DC. (Leguminosae), Haematostaphis barteri Hook. f. (Anacardiaceae), Mitragyna inermis (Willd.) O. Kuntze (Rubiaceae) and Pseudocedrela kotschyi (Schweinf.) Harms (Meliaceae), from Ghana were tested against Bacillus subtilis, Pseudomonas syringae and Cladosporium herbarum using TLC direct-autobiographic methods. Extracts from leaves, stem bark and roots of the four species gave a positive result against at least one test organism. Twelve of the 36 extracts were active against B. subtilis, four extracts were active against P. syringae and six were active against C. herbarum. Preliminary chemical analysis revealed the presence of flavonoids, stilbenes and alkaloids. This is the first report of a stilbene from the Anacardiaceae. Copyright © 2008 John Wiley & Sons, Ltd. [source] Insecticidal activities of secondary metabolites of endophytic Pencillium sp. in Derris elliptica BenthJOURNAL OF APPLIED ENTOMOLOGY, Issue 8 2005M. Y. Hu Abstract:, A strain of endophytic Pencillium sp., which might produce rotenone or its analogues and showed bioactivity against aphids, was isolated from the fresh roots of Derris elliptica Benth. A total of 12 fractions, isolated from the chloroform extract of endophytic Pencillium sp. mycelia by silica gel column, were tested by bioassay and high-performance liquid chromatography (HPLC), and the more bioactive fractions were found to be D, E and J. Against the adult turnip aphid, Lipaphis erysimi, by dipping at a concentration of 1 mg/ml, the corrected mortalities of fraction D, E and J were 57.68, 63.28 and 69.74% after 48 h of treatment respectively. The three fractions also showed strong antifeeding activity against third instar larvae of Plutella xylostella in a laboratory bioassay. One absorption peak was detected in the HPLC picture of fraction D, it had a similar retention time as that of rotenone, and the chemical constituent, related to the absoption peak, had the same ultraviolet absorption picture as that of rotenone. Then it could be further concluded that the bioactive compounds in the fraction D could be rotenone or its analogous compounds. [source] Crystal growth of some urinary stone constituents: II.CRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2002In-vitro crystallization of hippuric acid Abstract Hippuric acid [C6H5CONHCH2COOH], one of the organic chemical constituents of urinary stone is crystallized in silica gel under suitable pH conditions by double diffusion method. The grown crystals were characterized by density measurement, Fourier transform infrared spectroscopy, X-ray powder diffraction and thermogravimetric analysis. [source] Dissolved fraction of standard laboratory cladoceran food alters toxicity of waterborne silver to Ceriodaphnia dubia,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2008Jason M. Kolts Abstract The biotic ligand model (BLM) for the acute toxicity of cationic metals to aquatic organisms incorporates the toxicity-modifying effects of dissolved organic matter (DOM), but the default parameterization (i.e., assuming 10% of DOM is humic acid) does not differentiate DOM from different sources. We exposed a cladoceran (Ceriodaphnia dubia) to Ag in the presence of DOM from filtered YCT (standard yeast,Cerophyll®,trout chow food recommended by the U.S. Environmental Protection Agency [EPA] for cladocerans), from the Suwannee River (GA, USA; relatively little anthropogenic input), and from the Desjardins Canal in Hamilton (ON, Canada; receives treated municipal wastewater effluent). In all three treatments, the dissolved organic carbon (DOC) concentration was 2 mg/L (the concentration following addition of YCT slurry at the U.S. EPA,recommended volume ratio). The average 48-h median effects concentration (EC50) ratios for dissolved Ag in the presence and absence of DOM [i.e., (EC50 with DOM)/(EC50 without DOM)] were as follows: Suwannee River, 1.6; Desjardins Canal, 2.2; and YCT filtrate, 26.8. Therefore, YCT filtrate provided much more protection against Ag toxicity than that provided by DOM from the surface waters. The major spectral characteristic that differentiated YCT filtrate from the other two types of DOM was a strong tryptophan peak in the excitation,emission matrix for YCT. These results have important implications for interpreting Ag toxicity tests in which organisms are fed YCT, and they suggest BLM-calculated toxicity predictions might be improved by incorporating specific chemical constituents or surrogate indices of DOM. Another component of the protective effect against Ag toxicity, however, might be that the dissolved fraction of YCT served as an energy and/or nutrient source for C. dubia. [source] Toxicity and chemistry of aspen wood leachate to aquatic life: Field studyENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2003Barry R. Taylor Abstract A dark, toxic leachate has been observed around woodpiles of trembling aspen (Populus tremuloides Michx.) cut in winter for pulp or structural lumber. We measured production of leachate from 18 m3 of harvestable aspen logs stacked in an open field near Dawson Creek, British Columbia, Canada. The logpile began producing leachate during the first winter thaw and continued to do so for the duration of the two-year study (mean, 250 L/collection). Aspen leachate was characterized by dark color, acidic pH (5.0-6.5), elevated conductivity (200-500 ,S/cm), high to very high biochemical oxygen demand (500-5,000 mg/L) and total organic carbon concentrations (500-2,000 mg/L), variable levels of phenolic compounds (2-27 mg/L), and low dissolved oxygen tensions (<2 mg/L). In tests with rainbow trout (Oncorhynchus mykiss), Daphnia magna, and luminescent bacteria, the leachate varied from weakly toxic (median lethal concentration, >10%) to very toxic (median lethal concentration, <1%). The volume of leachate generated by the logpile was correlated with total precipitation (rain or snow) since the last collection. Loads of chemical constituents or toxicity (lethal concentration × volume) in the leachate did not decline over the duration of the study. Less than 10% of the total mass of leachable material in the aspen logs was removed during two years of exposure. [source] Trace metal distribution in soluble organic matter from municipal solid waste compost determined by size-exclusion chromatographyENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2002Arno Kaschl Abstract Municipal solid waste (MSW) composts carry high amounts of trace metals and organic complexing agents that may influence metal bioavailability and mobility after application to soils. In order to assess the degree of organic complexation of trace metals in the solution phase of MSW compost and the relevance of organic ligand type, size exclusion chromatography (SEC) was applied to compost-extracted organic ligands. Adjustment of the elution conditions minimized the interaction with the gel matrix for compost humic substances and dissolved organic matter (DOM) fractions. The SEC was then used to separate the aqueous compost extract into samples with distinct differences in chemical constituents. The highest quantities of Cu, Zn, Ni, Mn, and Cd were found to coelute with the main peak of the SEC elution curve, which, as observed by Fourier-transformed infrared (FTIR) spectroscopy, also had the highest density of carboxyl groups. The ratio of aromatic to aliphatic structures was higher for eluates with low retention times, and cations such as Al, Cr, and Fe were preferably associated with these larger organic molecules. All trace metals in the compost solution phase were bound mostly to DOM rather than forming inorganic complexes. [source] Optically Transparent Nanofiber PaperADVANCED MATERIALS, Issue 16 2009Masaya Nogi Optically transparent paper of densely packed cellulose nanofibers is prepared without any additives. This material has the same chemical constituents as conventional paper, the only difference being the fiber width and the size of the interstitial cavities. This optically transparent paper exhibits high Young's modulus, high strength, ultralow CTE, and high foldability. [source] | |||||||||||||||||||||||||||||||