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1.
Four new abscisic acid related compounds (1-4), together with (+)-abscisic acid (5), (+)-beta-D-glucopyranosyl abscisate (6), (6S,9R)-roseoside (7), and two lignan glucosides ((+)-pinoresinol mono-beta-D-glucopyranoside (8) and 3-(beta-D-glucopyranosyloxymethyl)-2- (4-hydroxy-3-methoxyphenyl)-5-(3-hydroxypropyl)-7-methoxy-(2R,3S)-dihydrobenzofuran (9)) were isolated from the antioxidative ethanol extract of prunes (Prunus domestica L.). The structures of 1-4 were elucidated on the basis of NMR and MS spectrometric data to be rel-5-(3S,8S-dihydroxy-1R,5S-dimethyl-7-oxa-6-oxobicyclo[3,2,1]oct-8-yl)-3-methyl-2Z,4E-pentadienoic acid (1), rel-5-(3S,8S-dihydroxy-1R,5S-dimethyl-7-oxa-6-oxobicyclo[3,2,1]oct-8-yl)-3-methyl-2Z,4E-pentadienoic acid 3'-O-beta-d-glucopyranoside (2), rel-5-(1R,5S-dimethyl-3R,4R,8S-trihydroxy-7-oxa-6-oxobicyclo[3,2,1]oct-8-yl)-3-methyl-2Z,4E-pentadienoic acid (3), and rel-5-(1R,5S-dimethyl-3R,4R,8S-trihydroxy-7-oxabicyclo[3,2,1]- oct-8-yl)-3-methyl-2Z,4E-pentadienoic acid (4). The antioxidant activities of these isolated compounds were evaluated on the basis of oxygen radical absorbance capacity (ORAC). The ORAC values of abscisic acid related compounds (1-7) were very low. Two lignans (8 and 9) were more effective antioxidants whose ORAC values were 1.09 and 2.33 micromol of Trolox equiv/micromol, respectively.  相似文献   

2.
Uptake and transformation of 14C-labeled metabolites from several pesticides, 3-methyl-4-nitrophenol (1), 3,5-dichloroaniline (2), 3-phenoxybenzoic acid (3), (R,S)-2-(4-chlorophenyl)-3-methylbutanoic acid (4), and (1RS)-trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid (5), were examined by using duckweed (Lemna gibba) in Hoagland's medium. More uptake into duckweed from the exposure water at pH 7.0 was observed for non-ionized 1 and 2 than for 3-5 in an ionized form, and their hydrophobicity accounted for these differences. While carboxylic acids 4 and 5 were scarcely transformed in duckweed, 1-3 mainly underwent phase II conjugation with glucose for 1 and 2, malic acid for 3, glutamic acid for 2, and malonylglucose for 3, the chemical identities of which were confirmed by various spectrometric analyses (LC-MS, LC-MS/MS, and NMR) and/or HPLC cochromatography with reference synthetic standards.  相似文献   

3.
As part of a project directed toward the discovery of new cancer chemopreventive agents from plants, two new natural products, asparagusic acid anti-S-oxide methyl ester (1) and asparagusic acid syn-S-oxide methyl ester (2), a new acetylenic compound, 2-hydroxyasparenyn [3',4'-trans-2-hydroxy-1-methoxy-4-[5-(4-methoxyphenoxy)-3-penten-1-ynyl]-benzene] (3), as well as eleven known compounds, asparenyn (4), asparenyol (5), (+/-)-1-monopalmitin (6), ferulic acid (7), 1,3-O-di-p-coumaroylglycerol (8), 1-O-feruloyl-3-O-p-coumaroylglycerol (9), blumenol C, (+/-)-epipinoresinol, linoleic acid, 1,3-O-diferuloylglycerol, and 1,2-O-diferuloylglycerol, were isolated from an ethyl acetate-soluble fraction of the methanol extract of the aerial parts of Asparagus officinalis (Asparagus), using a bioassay based on the inhibition of cyclooxygenase-2 to monitor chromatographic fractionation. The structures of compounds 1-3 were elucidated by 1D- and 2D-NMR experiments ((1)H NMR, (13)C NMR, DEPT, COSY, HMQC, HMBC and NOESY). All the isolates were evaluated for their inhibitory effects against both cyclooxygenase-1 and -2, with the most active compound being linoleic acid.  相似文献   

4.
Six volatile compounds, ethylmethylbenzene (1), 1-isopentyl-2,4, 5-trimethylbenzene (2), 2-(hex-3-ene-2-one)phenylmethyl ketone (3), E and Z isomers of 3-butylidene-3H-isobenzofuran-1-one (4 and 5), and 2-penten-1-ylbenzoic acid (6), were isolated from the mosquitocidal hexane extract of Delphinium x cultorum cv. Magic Fountains flowers. In addition, the ethyl acetate extract, which displayed corn earworm antifeedant activity, yielded 4-hydroxybenzoic acid (7) and bis(4-hydroxyphenyl)methanol (8). However, compounds 7 and 8 were not biologically active.  相似文献   

5.
Six triterpenoid saponins were isolated from the seeds of Chenopodium quinoa (Chenopodiaceae). Their structures were as follows: phytolaccagenic acid 3-O-[alpha-L-arabinopyranosyl-(1' '-->3')-beta-D-glucuronopyranosyl]-28-O-beta-D-glucopyranoside (1); spergulagenic acid 3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl-28-O-beta-D-glucopyranoside (2); hederagenin 3-O-[beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl]-28-O-beta-D-glucopyranoside (3); phytolaccagenic acid 3-O-[beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl]-28-O-beta-D-glucopyranoside (4); hederagenin 3-O-[beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl]-28-O-beta-D-glucopyranoside (5); and spergulagenic acid 3-O-[alpha-L-arabinopyranosyl-(1' '-->3')-beta-D-glucuronopyranosyl]-28-O-beta-D-glucopyranoside (6). Saponins 5 and 6 are new. The structures were characterized on the basis of hydrolysis and spectral evidence, including IR, UV, optical rotations, 1D- and 2D-NMR (HMQC and HMBC), ESIMS, and FABMS analyses.  相似文献   

6.
Maple syrup is made by boiling the sap collected from certain maple ( Acer ) species. During this process, phytochemicals naturally present in tree sap are concentrated in maple syrup. Twenty-three phytochemicals from a butanol extract of Canadian maple syrup (MS-BuOH) had previously been reported; this paper reports the isolation and identification of 30 additional compounds (1-30) from its ethyl acetate extract (MS-EtOAc) not previously reported from MS-BuOH. Of these, 4 compounds are new (1-3, 18) and 20 compounds (4-7, 10-12, 14-17, 19, 20, 22-24, 26, and 28-30) are being reported from maple syrup for the first time. The new compounds include 3 lignans and 1 phenylpropanoid: 5-(3″,4″-dimethoxyphenyl)-3-hydroxy-3-(4'-hydroxy-3'-methoxybenzyl)-4-(hydroxymethyl)dihydrofuran-2-one (1), (erythro,erythro)-1-[4-[2-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-1-(hydroxymethyl)ethoxy]-3,5-dimethoxyphenyl]-1,2,3-propanetriol (2), (erythro,threo)-1-[4-[2-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-1-(hydroxymethyl)ethoxy]-3,5-dimethoxyphenyl]-1,2,3-propanetriol (3), and 2,3-dihydroxy-1-(3,4- dihydroxyphenyl)-1-propanone (18), respectively. In addition, 25 other phenolic compounds were isolated including (threo,erythro)-1-[4-[(2-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-1-(hydroxymethyl)ethoxy]-3-methoxyphenyl]-1,2,3-propanetriol (4), (threo,threo)-1-[4-[(2-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-1-(hydroxymethyl)ethoxy]-3-methoxyphenyl]-1,2,3-propanetriol (5), threo-guaiacylglycerol-β-O-4'-dihydroconiferyl alcohol (6), erythro-1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-hydroxypropyl)-2,6-dimethoxyphenoxy]-1,3-propanediol (7), 2-[4-[2,3-dihydro-3-(hydroxymethyl)-5-(3-hydroxypropyl)-7-methoxy-2-benzofuranyl]-2,6-dimethoxyphenoxy]-1-(4-hydroxy-3-methoxyphenyl)-1,3-propanediol (8), acernikol (9), leptolepisol D (10), buddlenol E (11), (1S,2R)-2-[2,6-dimethoxy-4-[(1S,3aR,4S,6aR)-tetrahydro-4-(4-hydroxy-3,5-dimethoxyphenyl)-1H,3H-furo[3,4-c]furan-1-yl]phenoxy]-1-(4-hydroxy-3-methoxyphenyl)-1,3-propanediol (12), syringaresinol (13), isolariciresinol (14), icariside E4 (15), sakuraresinol (16), 1,2-diguaiacyl-1,3-propanediol (17), 2,3-dihydroxy-1-(4-hydroxy-3,5-dimethoxyphenyl)-1-propanone (19), 3-hydroxy-1-(4-hydroxy-3,5-dimethoxyphenyl)propan-1-one (20), dihydroconiferyl alcohol (21), 4-acetylcatechol (22), 3',4',5'-trihydroxyacetophenone (23), 3,4-dihydroxy-2-methylbenzaldehyde (24), protocatechuic acid (25), 4-(dimethoxymethyl)pyrocatechol (26), tyrosol (27), isofraxidin (28), and 4-hydroxycatechol (29). One sesquiterpene, phaseic acid (30), which is a known metabolite of the phytohormone abscisic acid, was also isolated from MS-EtOAc. The antioxidant activities of MS-EtOAc (IC(50) = 75.5 μg/mL) and the pure isolates (IC(50) ca. 68-3000 μM) were comparable to that of vitamin C (IC(50) = 40 μM) and the synthetic commercial antioxidant butylated hydroxytoluene (IC(50) = 3000 μM), in the diphenylpicrylhydrazyl radical scavenging assay. The current study advances scientific knowledge of maple syrup constituents and suggests that these diverse phytochemicals may impart potential health benefits to this natural sweetener.  相似文献   

7.
Twenty-three phenolic compounds were isolated from a butanol extract of Canadian maple syrup (MS-BuOH) using chromatographic methods. The compounds were identified from their nuclear magnetic resonance and mass spectral data as 7 lignans [lyoniresinol (1), secoisolariciresinol (2), dehydroconiferyl alcohol (3), 5'-methoxy-dehydroconiferyl alcohol (4), erythro-guaiacylglycerol-β-O-4'-coniferyl alcohol (5), erythro-guaiacylglycerol-β-O-4'-dihydroconiferyl alcohol (6), and [3-[4-[(6-deoxy-α-l-mannopyranosyl)oxy]-3-methoxyphenyl]methyl]-5-(3,4-dimethoxyphenyl)dihydro-3-hydroxy-4-(hydroxymethyl)-2(3H)-furanone (7)], 2 coumarins [scopoletin (8) and fraxetin (9)], a stilbene [(E)-3,3'-dimethoxy-4,4'-dihydroxystilbene (10)], and 13 phenolic derivatives [2-hydroxy-3',4'-dihydroxyacetophenone (11), 1-(2,3,4-trihydroxy-5-methylphenyl)ethanone (12), 2,4,5-trihydroxyacetophenone (13), catechaldehyde (14), vanillin (15), syringaldehyde (16), gallic acid (17), trimethyl gallic acid methyl ester (18), syringic acid (19), syringenin (20), (E)-coniferol (21), C-veratroylglycol (22), and catechol (23)]. The antioxidant activities of MS-BuOH (IC50>1000 μg/mL), pure compounds, vitamin C (IC50=58 μM), and a synthetic commercial antioxidant, butylated hydroxytoluene (IC50=2651 μM), were evaluated in the diphenylpicrylhydrazyl (DPPH) radical scavenging assay. Among the isolates, the phenolic derivatives and coumarins showed superior antioxidant activity (IC50<100 μM) compared to the lignans and stilbene (IC50>100 μM). Also, this is the first report of 16 of these 23 phenolics, that is, compounds 1, 2, 4-14, 18, 20, and 22, in maple syrup.  相似文献   

8.
Peroxidase extracted from Momordica charantia was used for the oligomerization of trans-resveratrol and ferulic acid on a preparative scale. One new heterocoupling oligomer, trans-3 E-3-[(4-hydroxy-3-methoxyphenyl)methylene]-4-(3,5-dihydroxyphenyl)-5-(4-hydroxyphenyl)tetrahydro-2-franone (6), and six resveratrol dimers, leachianol G (1), restrytisol B (2), parthenostilbenins A (3) and B (5), 7- O-acetylated leachianol G (4), and resveratrol trans-dehydrodimer (8), and one known ferulic acid dehydrodimer, (3alpha,3aalpha,6alpha,6aalpha)tetrahydro-3,6-bis(4-hydroxy-3-methoxyphenyl)-1 H,4 H-furo[3,4-c]furan-1,4-dione (7) were obtained. Bioactive experiments showed that compounds 6- 8 have strong free radical scavenging effects and also have protective effects on doxorubicin-induced cardiac cell injury when tested in vitro.  相似文献   

9.
Two novel caffeoylmalic acid methyl esters, 2-O-(trans-caffeoyl)malic acid 1-methyl ester (6) and 2-O-(trans-caffeoyl)malic acid 4-methyl ester (7), were isolated from pear (Pyrus pyrifolia Nakai cv. Chuhwangbae) fruit peels. In addition, 5 known hydroxycinnamoylmalic acids and their methyl esters were identified: 2-O-(trans-coumaroyl)malic acid (1), 2-O-(cis-coumaroyl)malic acid (2), 2-O-(cis-coumaroyl)malic acid 1-methyl ester (3), 2-O-(trans-coumaroyl)malic acid 1-methyl ester (4), and 2-O-(trans-caffeoyl)malic acid (phaselic acid, 5). The chemical structures of these compounds were determined by spectroscopic data from ESI MS and NMR. Of all the isolated compounds, five hydroxycinnamoylmalic acids and their methyl esters (2-4, 6, 7) were identified in the pear for the first time.  相似文献   

10.
Kynurenine (1) and indole-3-acetic acid (2) are considered as potential precursors of 2-aminoacetophenone (3), which is regarded to be the aroma impact compound causing an "untypical aging off-flavor" (UTA) in Vitis vinifera wines. The mechanism of the formation of 3 was studied using model fermentation and model sulfuration media spiked with 1 or 2 as potential precursors. Possible degradation products such as kynurenamine (4) and kynurenic acid (5), or skatole (6), 2-oxoskatole (7), 2-formamidoacetophenone (8), 2-oxindole-3-acetic acid (9), and 3-(2-formylaminophenyl)-3-oxopropionic acid (10) were evaluated by HPLC-UV of the fermentation and sulfuration media and comparison with synthesized 7, 8, 9, and 10. The synthesis of the possible precursor 4-(2-aminophenyl)-2,4-dioxobutanoic acid (11), a proposed metabolite of 1 failed because a spontaneous cyclization yields 5 and N-oxo-kynurenic acid (12), but not 11. It could be shown that the formation of 3 is triggered by an oxidative degradation of 2 after sulfuration with potassium bisulfite via the intermediates 10 and 8. However, no formation of 3 occurred during sulfuration of a model wine spiked with 1 or during fermentation of a model must spiked with 1 or 2.  相似文献   

11.
Eighteen triterpene saponins (1-18) from Medicago arborea leaves have been isolated and their structures elucidated by spectroscopic, spectrometric (1D and 2D NMR, FAB-MS, ESI-MS/MS), and chemical methods. They have been identified as glycosides of medicagenic, zanhic, and 2beta-hydroxyoleanolic acids, soyasapogenol B, bayogenin, and 2beta,3beta-dihydroxyolean-12-en-23-al-28-oic acid. Twelve of them, identified as 3-O-beta-D-glucopyranosyl-28-O-[alpha-L-arabinopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside] zanhic acid (3), 3-O-beta-D-glucopyranosyl-28-O-[beta-D-xylopyranosyl(1-->4)-[alpha-L-arabinopyranosyl-(1-->3)]-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside] zanhic acid (4), 3-O-[alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranosyl(1-->2)-beta-D-glucopyranosyl]-2beta-hydroxyoleanolic acid (5), 3-O-beta-D-glucuronopyranosyl-28-O-[alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside]medicagenic acid (6), 3-O-beta-D-glucuronopyranosyl-28-O-[beta-D-xylopyranosyl(1-->4)-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside]bayogenin (9), 3-O-beta-D-glucuronopyranosyl-28-O-[beta-D-xylopyranosyl(1-->4)-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside]-2beta,3beta-dihydroxyolean-12-en-23-al-28-oic acid (10), 3-O-beta-D-glucuronopyranosyl-28-O-[beta-D-xylopyranosyl(1-->4)-[beta-D-apiofuranosyl(1-->3)]-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside]zanhic acid (12), 3-O-beta-D-glucuronopyranosyl-28-O-[beta-D-xylopyranosyl(1-->4)-[alpha-L-arabinopyranoside(1-->3)]-alpha-L-rhamnopyrano-syl(1-->2)-alpha-L-arabinopyranoside]zanhic acid (13), 3-O-beta-D-glucuronopyranosyl-28-O-[beta-D-xylopyrano-syl(1-->4)-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside]zanhic acid (14), 3-O-[alpha-L-arabinopyranosyl-(1-->2)-beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-28-O-[beta-D-xylopyranosyl(1-->4)-[beta-D-apiofurano-syl(1-->3)]-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside]zanhic acid (16), 3-O-[beta-D-glucopyrano-syl(1-->2)-beta-D-glucopyranosyl]-28-O-[beta-D-xylopyranosyl(1-->4)-[alpha-L-arabinopyranosyl(1-->3)]-alpha-L-rhamno-pyranosyl (1-->2)-alpha-L-arabinopyranoside]zanhic acid (17), and 3-O-beta-D-glucuronopyranosyl-28-O-[beta-D-xylopyranosyl(1-->4)-[beta-D-apiofuranosyl(1-->3)]-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyrano-side]medicagenic acid (18), are reported as new natural compounds. The presence of the aldehydic group on the sapogenin moiety of saponin 10 is discussed in the framework of a possible elucidation of the biosynthesis of these metabolites.  相似文献   

12.
The major in vivo metabolites of S-(+)- and R-(-)-carvone in a metabolism of ingestion correlated amounts (MICA) experiment were newly identified as alpha,4-dimethyl-5-oxo-3-cyclohexene-1-acetic acid (dihydrocarvonic acid), alpha-methylene-4-methyl-5-oxo-3-cyclohexene-1-acetic acid (carvonic acid), and 5-(1,2-dihydroxy-1-methylethyl)-2-methyl-2-cyclohexen-1-one (uroterpenolone) on the basis of mass spectral analysis in combination with syntheses and NMR experiments. Minor metabolites were identified as reduction products of carvone, namely, the alcohols carveol and dihydrocarveol. The previously identified major in vivo metabolite in rabbits, 10-hydroxycarvone, could not be detected, indicating either concentration effects or interspecies differences. Metabolic pathways for carvone in humans including oxidation of the double bond in the side chain and, to a minor extent 1,2- and 1,4 + 1,2-reduction of carvone, are discussed. No differences in metabolism between S-(+)- and R-(-)-carvone were detected.  相似文献   

13.
Six compounds, 1-O-(2,3, 4-trihydroxy-3-methyl)butyl-6-O-feruloyl-beta-D-glucopyranoside, ethyl beta-D-glucopyranosyl tuberonate, p-hydroxybenzoic acid, (-)-hydroxyjasmonic acid, caffeic acid, and 4-hydroxyacetophenone 4-O-[5-O-(3, 5-dimethoxy-4-hydroxybenzoyl)-beta-D-apiofrunosyl]-(1-->2)-beta-D- glu copyranoside, were isolated from the n-butanol-soluble fraction of sage leaf extracts. Their structures were determined by spectral methods (MS, NMR, and 2D-NMR), and their antioxidant activities were measured. Among them, two new glycosides were elucidated. All of these compounds showed DPPH free radical scavenging activity at the concentration of 30 mM, and caffeic acid was the most active compound.  相似文献   

14.
A total of 19 naturally occurring bromophenols, with six new and 13 known structures, were isolated and identified from the methanolic extract of the marine red alga Rhodomela confervoides. The new compounds were identified by spectroscopic methods as 3,4-dibromo-5-((methylsulfonyl)methyl)benzene-1,2-diol (1), 3,4-dibromo-5-((2,3-dihydroxypropoxy)methyl)benzene-1,2-diol (2), 5-(aminomethyl)-3,4-dibromobenzene-1,2-diol (3), 2-(2,3-dibromo-4,5-dihydroxyphenyl)acetic acid (4), 2-methoxy-3-bromo-5-hydroxymethylphenol (5), and (E)-4-(2-bromo-4,5-dihydroxyphenyl)but-3-en-2-one (6). Each compound was evaluated for free radical scavenging activity against DPPH (α,α-diphenyl-β-dipicrylhydrazyl) and ABTS [2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt] radicals. Most of them exhibited potent activities stronger than or comparable to the positive controls butylated hydroxytoluene (BHT) and ascorbic acid. The results from this study suggest that R. confervoides is an excellent source of natural antioxidants, and inclusion of these antioxidant-rich algal components would likely help prevent the oxidative deterioration of food.  相似文献   

15.
Application of aroma extract dilution analysis (AEDA) on the volatile components of low-, medium-, and high-heat-treated nonfat dry milks (NDM) revealed aroma-active compounds in the log(3) flavor dilution (log(3) FD) factor range of 1 to 6. The following compounds contributed the highest log(3) FD factors to overall NDM flavor: 2,5-dimethyl-4-hydroxy-3(2H)-furanone [(Furaneol), burnt sugar-like]; butanoic acid (rancid); 3-(methylthio)propanal [(methional), boiled potato-like]; o-aminoacetophenone (grape-like); delta-decalactone (sweet); (E)-4,5-epoxy-(E)-2-decenal (metallic); pentanoic acid (sweaty); 4,5-dimethyl-3-hydroxy-2(5H)-furanone [(sotolon), curry]; 3-methoxy-4-hydroxybenzaldehyde [(vanillin), vanilla]; 2-acetyl-1-pyrroline and 2-acetyl-2-thiazoline (popcorn-like); hexanoic acid (vinegar-like); phenylacetic acid (rose-like); octanoic acid (waxy); nonanal (fatty); and 1-octen-3-one (mushroom-like). The odor intensities of Furaneol, butanoic acid, methional, o-aminoacetophenone, sotolon, vanillin, (E)-4,5-epoxy-(E)-2-decenal, and phenylacetic acid were higher in high-heat-treated samples than others. However, the odor intensities of lactones, 2-acetyl-1-pyrroline, and 2-acetyl-2-thiazoline were not affected by heat treatment. Sensory evaluation results also revealed that heat-generated flavors have a major impact on the flavor profile of NDM.  相似文献   

16.
Green tea, tara tannin, and tannic acid have been profiled for their contents of galloylquinic acids using LC-MS8. These procedures have provided evidence for the first observation of (i) 1-galloylquinic acid (11), 1,3,5-trigalloylquinic acid (22), 4-(digalloyl)quinic acid (28), 5-(digalloyl)quinic acid (29), and either 3-galloyl-5-(digalloyl)quinic acid (32) or 3-(digalloyl)-5-galloylquinic acid (33) from any source; (ii) 4-galloyl-5-(digalloyl)quinic acid (34), 5-galloyl-4-(digalloyl)quinic acid (35), 3-(digalloyl)-4,5-digalloylquinic acid (41), 4-(digalloyl)-3,5-digalloylquinic acid (40), 5-(digalloyl)-3,4-digalloylquinic acid (39), and 1,3,4-trigalloylquinic acid (21) from tara tannin; and (iii) 3-galloylquinic acid (12) and 4-galloylquinic acid (14) from green tea. The first mass spectrometric fragmentation data are reported for galloylquinic acids containing between five and eight gallic acid residues. For each of these mass ranges at least two isomers based on the 1,3,4,5-tetragalloylquinic acid core (25) and at least three based on the 3,4,5-trigalloylquinic acid core (24) were observed. Methanolysis of tara tannin yielded methyl gallate, methyl digallate, and methyl trigallate, demonstrating that some of these galloylquinic acids contained at least one side chain of up to four galloyl residues.  相似文献   

17.
The resorcylic acid lactones zearalenone ( 1), alpha-zearalenol ( 2), beta-zearalenol ( 3), alpha-zearalanol (zeranol) ( 4), beta-zearalanol (taleranol) ( 5), and zearalanone ( 6) were converted to their glucuronides on a preparative scale in good yields. Reactions were conducted with bovine uridine 5'-diphosphoglucuronyl transferase (UDPGT) as catalyst and uridine 5'-diphosphoglucuronic acid (UDPGA) as cofactor. The glucuronides were isolated by column chromatography and characterized by NMR spectroscopy and mass spectrometry. Although the principal products were 4- O-glucuronides (i.e., linkage through a phenolic hydroxyl), significant quantities of the 6'- O-glucuronides (i.e., linkage through the aliphatic hydroxyl) of alcohols 2, 4, and 5 were also isolated. In the case of 3, the 2- O-glucuronide was isolated as the minor product. Overall isolated yields of glucuronides, performed on a 20-50 mg scale, were typically ca. 80% based on the resorcylic acid lactone starting material. LC-UV-MS (2) analysis of purified specimens revealed MS (2) fragmentations useful for defining the point of attachment of the glucuronide moiety to the zearalenone nucleus.  相似文献   

18.
The dimethyl derivatives of imazaquin, imazapyr, imazmethapyr, imazethapyr, 2-[4,5 dihydro-1, 4-dimethyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methoxymethyl- 3-pyridine carboxylic acid, 2-[4,5-dihydro-1,4 -dimethyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-4-methyl benzoic acid, and 2-[4,5-dihydro-1,4-dimethyl-4-(1-methyl ethyl)-5-oxo-1H-imidazol-2-yl]-5-methyl benzoic acid were prepared and fully characterized. The availability of these derivatives has led to the development of efficient and multiresidue gas chromatographic methods for trace level analysis of imidazolinone herbicides in matrixes such as water, soybean, and soil.  相似文献   

19.
Antioxidative compounds from the outer scales of onion   总被引：2，自引：0，他引：2  
Antioxidative compounds were isolated from the methanol extract of dry outer scales of onion (Allium cepa L.). Nine phenolic compounds (1-9) were finally obtained by reversed-phase high-performance liquid chromatography, and their structures were elucidated by NMR and mass spectrometry analyses. They were the six known compounds, protocatechuic acid (1), 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (2), quercetin 4'-O-beta-D-glucopyranoside (3), quercetin (5), 4'-O-beta-d-glucopyranoside of quercetin dimer (7), and quercetin dimer (8), and three novel compounds, condensation products of quercetin with protocatechuic acid (4), adduct of quercetin with quercetin 4'-O-beta-D-glucopyranoside (6), and quercetin trimer (9). These phenolic compounds were tested for their antioxidant properties using autoxidation of methyl linoleate in bulk phase or free radical initiated peroxidation of soybean phosphatidylcholine in liposomes. The flavonoid compounds having o-dihydroxy substituent in the B-ring were shown to be effective antioxidants against nonenzymic lipid peroxidation.  相似文献   

20.
High-resolution gas chromatography in combination with mass spectrometry and high-resolution mass spectrometry was used to determine the positions and extent of labeling in the metabolites of carvone, namely in alpha,4-dimethyl-5-oxo-3-cyclohexene-1-acetic acid (dihydrocarvonic acid), alpha-methylene-4-methyl-5-oxo-3-cyclohexene-1-acetic acid (carvonic acid), and 5-(1,2-dihydroxy-1-methylethyl)-2-methyl-2-cyclohexen-1-one (uroterpenolone), after human ingestion of 9,9-dideutero- and 9-(13)C-carvone. Carvonic acid was formed by oxidation at the methyl carbon of the isopropenyl group of carvone, whereas dihydrocarvonic acid was formed by oxidation at the methylene position, most probably via carvone epoxide. A "nonaromatic" NIH shift must occur during the subsequent reactions yielding dihydrocarvonic acid. Additionally, dehydrogenation of dihydrocarvonic acid and hydrogenation of carvonic acid were observed, resulting in minor amounts of both acids owning a carboxy group of opposite origin. Uroterpenolone was found to be exclusively formed by oxidation at the methylene carbon of the isopropenyl group of carvone, and thus, most probably by hydrolysis of carvone epoxide.  相似文献   

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