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1.
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   

2.
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   

3.
Covalently cross-linked proteins are among the major modifications caused by the advanced Maillard reaction. So far, the chemical nature of these aggregates is largely unknown. Investigations are reported on the isolation of 6-[2-[[(4S)-4-amino-4-carboxybutyl]amino]-6,7-dihydroxy-6,7-dihydroimidazo[4,5-b]azepin-4(5H)-yl]-L-norleucine (10) and N-acetyl-6-[(6R,7R)-2-[[4-(acetylamino)-4-carboxybutyl]amino]-6,7,8a-trihydroxy-6,7,8,8a-tetrahydroimidazo[4,5-b]azepin-4(5H)-yl]-L-norleucine (12) formed by oxidation of the major Maillard cross-link glucosepane 1. Independent synthesis and unequivocal structural characterization are given for 10 and 12. Spiro cross-links, representing a new class of glycoxidation products, were obtained by dehydrogenation of the amino imidazolinimine compounds N6-[2-[[(4S)-4-ammonio-5-oxido-5-oxopentyl]amino]-5-[(2S,3R)-2,3,4-trihydroxybutyl]-3,5-dihydro-4H-imidazol-4-ylidene]-L-lysinate (DOGDIC 2) and N6-[2-[[(4S)-4-ammonio-5-oxido-5-oxopentyl]amino]-5-[(2S)-2,3-dihydroxypropyl]-3,5-dihydro-4H-imidazol-4-ylidene]-L-lysinate (DOPDIC 3). These new oxidation products were synthesized, and their unambiguous structural elucidation proved the formation of the spiro imidazolimine structures N6-[(7R,8S)-2-[[(4S)-4-ammonio-5-oxido-5-oxopentyl]amino]-8-hydroxy-7-(hydroxymethyl)-6-oxa-1,3-diazaspiro[4.4]non-1-en-4-ylidene]-L-lysinate (16), N6-(8R,9S)-2-[(4S)-4-ammonio-5-oxido-5-oxopentyl]amino]-8,9-dihydroxy-6-oxa-1,3-diazaspiro[4.5]dec-1-en-4-ylidene)-L-lysinate (19), and N6-[(8S)-2-[(4-amino-4-carboxybutyl)amino]-8-hydroxy-6-oxa-1,3-diazaspiro[4.4]non-1-en-4-ylidene]-L-lysinate (18), respectively. It was shown that reaction of the imidazolinone 15 led to the formation of spiro imidazolones, structurally analogous to 16 and 19.  相似文献   

4.
In order to find new flavor modifiers, various short chain gingerdione derivatives were synthesized as structural analogues of the known bitter masker homoeriodictyol and evaluated by a sensory panel for masking and sweetness enhancing activities. 1-(4-Hydroxy-3-methoxyphenyl)hexa-3,5-dione ([2]-gingerdione) and the homologue 1-(4-hydroxy-3-methoxyphenyl)hepta-3,5-dione ([3]-gingerdione) at concentration ranges 50-500 mg kg (-1) showed the most promising masking activity of 20-30% against bitterness of a 500 mg kg (-1) aqueous caffeine solution. Additionally, both compounds were able to reduce the bitterness of a 5 mg kg (-1) quinine solution by about 20%; however, the bitter tastes of salicine, the model peptide H-Leu-Trp-OH, and KCl solutions were not reduced. Whereas for bitter masking activity a vanillyl moiety seems to be important, some of the tested isovanillyl isomers showed an interesting sweet enhancing effect without exhibiting a significant intrinsic sweetness. The isomer 1-(3-hydroxy-4-methoxyphenyl)hexa-3,5-dione ([2]-isogingerdione) at 100 mg kg (-1) caused a significant and synergistic increase of 27% of sweet taste of a 5% sucrose solution.  相似文献   

5.
Aqueous sugar (glucose or xylose)-lysine model systems were heated at 80 degrees C for 6 h with the pH maintained at a predetermined value (3, 4, or 5). Selected compounds were isolated by combinations of solvent extraction and semipreparative HPLC, prior to identification by NMR and mass spectrometry. Two compounds were identified from the pH 5 glucose system and were identified as epsilon-[2-formyl-5-(hydroxymethyl)pyrrole-1-yl]-L-norleucine (pyrraline) and the new compound, 1-(5-carboxy-5-aminopentyl)-2-formyl-3-(1,2,3-trihydroxypropyl)pyrrole. A third compound was partially characterized. 2-Acetyl-5-hydroxymethyl-5,6-dihydro-4H-pyridinone was identified in the pH 3 xylose system, and the new compound, 8-furan-2-yl-methyl-5-hydroxymethyl-5,6-dihydro-indolizine-1,7-dione, was identified in the pH 4 xylose system. 2-Furfurylidene-4-hydroxy-5-methyl-3(2H)-furanone was identified in both xylose systems. Mechanisms of formation are proposed for the novel compounds.  相似文献   

6.
A new bicyclic diarylheptanoid, rel-(3S,4aR,10bR)-8-hydroxy-3-(4-hydroxyphenyl)-9-methoxy-4a,5,6,10b-tetrahydro-3H-naphtho[2,1-b]pyran (1), as well as four known compounds, 1,2-dihydro-1,2,3-trihydroxy-9-(4-methoxyphenyl)phenalene (2), hydroxyanigorufone (3), 2-(4-hydroxyphenyl)naphthalic anhydride (4), and 1,7-bis(4-hydroxyphenyl)hepta-4(E),6(E)-dien-3-one (5), were isolated from an ethyl acetate-soluble fraction of the methanol extract of the fruits of Musa x paradisiaca cultivar, using a bioassay based on the induction of quinone reductase (QR) in cultured Hepa1c1c7 mouse hepatoma cells to monitor chromatographic fractionation. The structure and relative stereochemistry of compound 1 were elucidated unambiguously by one- and two-dimensional NMR experiments ((1)H NMR, (13)C NMR, DEPT, COSY, HMQC, HMBC, and NOESY) and single-crystal X-ray diffraction analysis. Isolates 1-5 were evaluated for their potential cancer chemopreventive properties utilizing an in vitro assay to determine quinone reductase induction and a mouse mammary organ culture assay.  相似文献   

7.
Dehydrodimers of hydroxycinnamates play an important role in the cross-linking of plant cell walls. An aqueous solution of quaternary ammonium salts with a long aliphatic chain is known to spontaneously organize itself into micelles with the ionic part at the outer sphere. It is shown that regioisomeric ferulic acid dehydrodimers can be obtained in one step from trans-ferulic acid after attachment to these micelles and using the biomimetic peroxidase-H2O2 system. The surfactant hexadecyltrimethylammonium hydroxide yielded trans-4-(4-hydroxy-3-methoxybenzylidene)-2-(4-hydroxy-3-methoxyphenyl)-5-oxotetrahydrofuran-3-carboxylic acid (25%), (E,E)-4,4'-dihydroxy-5,5'-dimethoxy-3,3'-bicinnamic acid (21%), and trans-5-[(E)-2-carboxyvinyl]-2-(4-hydroxy-3-methoxyphenyl)-7-methoxy-2,3-dihydrobenzofuran-3-carboxylic acid (14%), whereas the surfactant tetradecyltrimethylammonium bromide gave 4-cis, 8-cis-bis(4-hydroxy-3-methoxyphenyl)-3,7-dioxabicyclo[3.3.0]octane-2,6-dione (18%) as the main product. The use of micelles appears to be not only a new way to synthesize regioisomeric ferulic acid dehydrodimers but may also help to understand the regiospecificity of dimeric hydroxycinnamate formation in vivo.  相似文献   

8.
Aqueous sugar (xylose or glucose)-glycine model systems were refluxed for 2 h with the pH maintained at 5. Reverse-phase HPLC of the total reaction products gave two resolved peaks (one of which was colored) for the xylose system and five resolved peaks (two of which were colored) for the glucose system. The components responsible for these peaks were isolated from the ethyl acetate extracts by semipreparative HPLC. Using mainly NMR, the colored compound from the xylose system was identified as the new 2-acetyl-6-(hydroxymethyl)-5,6-dihydro-4H-pyridinone. The colored compounds from the glucose system were most likely to be two novel cis/trans ring isomers of the related new compound 2-acetyl-6-hydroxy-7-(hydroxymethyl)-1,5,6,7-tetrahydro-4H-azepinone+ ++. These compounds are the first one-ring structures isolated from sugar-amino acid model systems that are reported to be colored. Two of the colorless components of the glucose system were identified, mainly by NMR experiments, as the related compounds 4-hydroxy-2-(hydroxymethyl)-5-methyl-3(2H)-furanone and 2, 3-dihydro-3,5-dihydroxy-6-methyl-4H-pyranone. The remaining compound from the glucose system and the colorless compound from the xylose system were identified as 5-(hydroxymethyl)furfural and 4-hydroxy-5-methyl-3(2H)-furanone, respectively.  相似文献   

9.
Six compounds were isolated from fresh rhizomes of fingerroot (Boesenbergia pandurata Schult.) as strong antimutagens toward 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) in Salmonella typhimurium TA98. These compounds were 2',4',6'-trihydroxychalcone (pinocembrin chalcone; 1), 2',4'-dihydroxy-6'-methoxychalcone (cardamonin; 2), 5,7-dihydroxyflavanone (pinocembrin; 3), 5-hydroxy-7-methoxyflavanone (pinostrobin; 4), (2,4,6-trihydroxyphenyl)-[3'-methyl-2'-(3' '-methylbut-2' '-enyl)-6'-phenylcyclohex-3'-enyl]methanone (5), and (2,6-dihydroxy-4-methoxyphenyl)-[3'-methyl-2'-(3' '-methylbut-2' '-enyl)-6'-phenylcyclohex-3'-enyl]methanone (panduratin A; 6). Compound 5 was a novel compound (tentatively termed 4-hydroxypanduratin A), and 1 was not previously reported in this plant, whereas 2-4 and 6 were known compounds. The antimutagenic IC(50) values of compounds 1-6 were 5.2 +/- 0.4, 5.9 +/- 0.7, 6.9 +/- 0.8, 5.3 +/- 1.0, 12.7 +/- 0.7, and 12.1 +/- 0.8 microM in the preincubation mixture, respectively. They also similarly inhibited the mutagenicity of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). All of them strongly inhibited the N-hydroxylation of Trp-P-2. Thus, the antimutagenic effect of compounds 1-6 was mainly due to the inhibition of the first step of enzymatic activation of heterocyclic amines.  相似文献   

10.
In the course of our study on the isolation and structure determination of constituents in tropical plants, we focused on Peucedanum japonicum Thunb., belonging to the family Umbelliferae. In this study, a new C(13) norisoprenoid glucoside, (3S)-O-beta-d-glucopyranosyl-6-[3-oxo-(2S)-butenylidenyl]-1,1,5-trimethylcyclohexan-(5R)-ol (1), and two new phenylpropanoid glucosides, 3-(2-O-beta-d-glucopyranosyl-4-hydroxyphenyl)propanoic acid (3) and methyl 3-(2-O-beta-d-glucopyranosyl-4-hydroxyphenyl)propanoate (4), were isolated from the n-butanol soluble fraction of this plant's leaves, together with five known compounds. The structures of these compounds were determined on the basis of spectroscopic evidence. In addition, all isolated compounds were examined for scavenging activity against 1,1-diphenyl-2-picrylhydrazyl radical and inhibitory activity against mushroom tyrosinase. These results suggested that 2-(4-hydroxy-3-methoxyphenyl)propane-1,3-diol (7) and 3-O-beta-d-glucopyranosyl-2-(4-hydroxy-3-methoxyphenyl)propanol (8) showed an appreciable activity in both assay systems.  相似文献   

11.
Two novel glucosides of 6-gingerdiol were isolated from fresh ginger (Zingiber officinale Roscoe). Their structures were determined as 1-(4-O-beta-D-glucopyranosyl-3-methoxyphenyl)-3,5-dihydroxydecane (1) and 5-O-beta-D-glucopyranosyl-3-hydroxy-1-(4-hydroxy-3-methoxyphenyl)deca ne (2) by HRFAB-MS and NMR analyses, and the absolute configurations of both aglycons were identified as (3S,5S) by a comparison with synthetic compounds. After incubating these glucosides with acetone powder prepared from fresh ginger, they were confirmed to have been hydrolyzed to 6-gingerdiol by HPLC. This result suggests that these glucosides are the precursors or intermediates of 6-gingerdiol. To recognize their function, their antioxidative activities were investigated and compared to that of their aglycon, 6-gingerdiol, by a linoleic acid model system and by their DPPH radical-scavenging ability. Although 1 did not indicate any activity, 2 had as strong activity as the aglycon in both measurements.  相似文献   

12.
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   

13.
Sequential application of solvent extraction, gel permeation chromatography, and RP-HPLC in combination with taste dilution analyses, followed by LC-MS and 1D/2D NMR experiments, led to the discovery and structure determination of 25 key astringent compounds of red currant juice. Besides several flavonol glycosides, in particular, 3-carboxymethyl-indole-1-N-beta-D-glucopyranoside, 3-methylcarboxymethyl-indole-1-N-beta-D-glucopyranoside, and a family of previously not identified compounds, namely, 2-(4-hydroxybenzoyloxymethyl)-4-beta-D-glucopyranosyloxy-2(E)-butenenitrile, 2-(4-hydroxy-3-methoxybenzoyloxymethyl)-4-beta-D-glucopyranosyloxy-2(E)-butenenitrile, (E)-6-[3-hydroxy-4-(O-beta-D-glucopyranosyl)phenyl]-5-hexen-2-one named dehydrorubrumin, and (3E,5E)-6-[3-hydroxy-4-(O-beta-D-glucopyranosyl)phenyl]-3,5-hexadien-2-one named rubrumin, have been identified. Determination of the oral astringency thresholds by means of the half-tongue test revealed that the lowest thresholds of 0.3 and 1.0 nmol/L were found for the nitrogen-containing 3-carboxymethyl-indole-1-N-beta-D-glucopyranoside and 3-methylcarboxymethyl-indole-1-N-beta-D-glucopyranoside, which do not belong to the group of plant polyphenols.  相似文献   

14.
  相似文献   

15.
This study investigated the biotransformation of the dicarboximide fungicide vinclozolin [3-(3,5-dichlorophenyl)-5-methyl-5-vinyl-1,3-oxazolidine-2,4-dione] by the fungus Cunninghamella elegans. Experiments with phenyl-[U-ring-14C]vinclozolin showed that after 96 h incubation, 93% had been transformed to four major metabolites. Metabolites were separated by HPLC and characterized by mass and NMR spectroscopy. Biotransformation occurred predominantly on the oxazolidine-2,4-dione portion of vinclozolin. The metabolites were identified as the 3R- and 3S- isomers of 3',5'-dichloro-2,3,4-trihydroxy-2-methylbutyranilide, N-(2-hydroxy-2-methyl-1-oxobuten-3-yl)-3,5-dichlorophenyl-1-carbamic acid, and 3',5'-dichloro-2-hydroxy-2-methylbut-3-enanilide. The enanilide compound has been reported previously as a plant and mammalian metabolite and is implicated to contain antiandrogenic activity. The 3R- and 3S- isomers of 3',5'-dichloro-2,3,4-trihydroxy-2-methylbutyranilide are novel metabolites.  相似文献   

16.
Defatted cinnamon fruit powder was successively extracted with benzene ethyl acetate, acetone, MeOH, and water. The concentrated water extract contained the maximum amount of phenolics and showed the highest antioxidant activities. Hence, it was fractionated by Diaion HP-20SS, Diaion HP-20, and Sephadex LH-20 column chromatographies. It gave five purified compounds, the purities of which were analyzed by HPLC. Compounds 1-5 were identified as 3,4-dihydroxybenzoic acid (protocatechuic acid), epicatechin-(2beta-->O-7,4beta-->8)-epicatechin-(4beta-->8)-epicatechin (cinnamtannin B-1), 4-[2,3-dihydro-3-(hydroxymethyl)-5-(3-hydroxypropyl)-7-(methoxy)benzofuranyl]-2-methoxyphenyl beta-d-glucopyranoside (urolignoside), quercetin-3-O-(6-O-alpha-l-rhamnopyranosyl)-beta-d-glucopyranoside (rutin), and quercetin-3-O-alpha-l-rhamnopyranoside by using extensive spectral studies. The antioxidant activities of purified compounds were screened for their antioxidative potential using beta-carotene-linoleate and 1,1-diphenyl-2-picrylhydrazyl model systems. All of the compounds showed antioxidant and radical scavenging activities. This is the first report of the isolation and identification of nonvolatile constituents and as well as antioxidant activities from cinnamon fruits.  相似文献   

17.
Six new compounds, trans-3-isobutyl-4-[4-(3-methyl-2-butenyloxy)phenyl]pyrrolidine-2,5-dione (1), trans-1-hydroxy-3-(4-hydroxyphenyl)-4-isobutylpyrrolidine-2,5-dione (2), cis-3-(4-hydroxyphenyl)-4-isobutyldihydrofuran-2,5-dione (3), 3-(4-hydroxyphenyl)-4-isobutyl-1H-pyrrole-2,5-dione (4), 3-(4-hydroxyphenyl)-4-isobutylfuran-2,5-dione (5), and dimethyl 2-(4-hydroxyphenyl)-3-isobutylmaleate (6), together with one known compound, 3-isobutyl-4-[4-(3-methyl-2-butenyloxy)phenyl]furan-2,5-dione (7), were isolated from the fruiting bodies of Antrodia camphorata. The structures of the compounds were elucidated by analysis of their spectroscopic data. To investigate the immunomodulatory potential of the compounds, RAW264.7 macrophage cells were treated with the compounds. Compound 1 significantly increased spontaneous TNF-alpha secretion from unstimulated RAW264.7 cells but suppressed IL-6 production [50% inhibition concentration value (IC50) = 10 microg/mL] in LPS-stimulated cells. Compounds 3, 4, and 6 also suppressed IL-6 production with IC50 values of 17, 18, and 25 microg/mL, respectively, suggesting that these four compounds may have an anti-inflammatory effect on macrophage-mediated responses. Of the six compounds, compound 1 was the most effective, exerting both immunostimulatory and anti-inflammatory effects.  相似文献   

18.
It was observed that the beta-O-4 bond cleavage of a dimeric phenolic lignin model compound with an alpha-carbonyl group at the B-ring, 2-(2-ethoxy-4-formylphenoxy)-1-(4-hydroxy-3-methoxyphenyl)propane-1,3-diol (I), is extremely fast in a mild anaerobic alkaline treatment (0.45 mol/L NaOH, 95 degrees C, 0.8 MPa of N2). This phenomenon significantly contrasts with the case of a common dimeric phenolic lignin model compound without any specific functional group, 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)propane-1,3-diol (II). The most plausible mechanism is the migration of the B-ring from the beta- to the alpha-position following the SNAr mechanism. Because this migration affords the alkaline labile phenolic alpha-O-4-type compound (XI), the formation of the quinone methide as well as the cleavage of the originally alkaline very stable alkyl-aryl ether bond is promoted. This promotion of the quinone methide formation explains why a relatively large amount of 4-hydroxy-3-methoxybenzaldehyde (IV) is produced from I in an oxygen-alkali treatment.  相似文献   

19.
1,2-Diarylpropane-1,3-diol-type lignin model compounds, 1,2-bis(4-hydroxy-3-methoxyphenyl)propane-1,3-diol (1) and 1-(3,4-diethoxyphenyl)-2-(4-methoxyphenyl)propane-1,3-diol (2), were pyrolyzed at 500 degrees C for 4 s to clarify the thermal behavior of beta-1 subunits in lignin. Products were monitored by gas chromatography/mass spectrometry. The cleavage of the Calpha-Cbeta bond to produce benzaldehydes such as 4-hydroxy-3-methoxybenzaldehyde (9) and phenylethanals as the counterparts such as 4-hydroxy-3-methoxyphenylethanal (10) occurred in pyrolyses of both 1 and 2. In pyrolysis of 1, an oxetane pathway leading to the formation of Z/E-stilbenes without the gamma-CH2OH group such as Z/E-4,4'-dihydroxy-3,3'-dimethoxystilbene (3) was predominant. In pyrolysis of 2, the oxetane pathway was minor, while pathways producing a dimer with a =CgammaH2 group by loss of water and a dimer with an alpha-carbonyl group were predominant. Pyrolysis of Japanese cedar wood provided 3 and 10 in approximately 0.8% and 0.6% yields, respectively, based on the Klason lignin content, while pyrolysis of a guaiacyl bulk dehydrogenation polymer gave them in a very small amount.  相似文献   

20.
LC/MS analysis of cyclohexanedione oxime herbicides in water   总被引：1，自引：0，他引：1  
A multiresidue method for the determination of alloxydim (methyl 2, 2-dimethyl-4, 6-dioxo-5-[1-[2-propenyloxy)amino]butylidene]cyclohexanec arb oxylate), clethodim (E, E)-(+/-)-2-[1-[[3-chloro-2-propenyl)oxy]imino]propyl]-5-[2-(ethylthio )propyl]-3-hydroxy-2-cyclohexen-1-one), sethoxydim ((+/-)-2-[1-(ethoxyimino)butyl]-5-[2-ethylthio)propyl]-3-hydroxy-2 -cy clohexen-1-one), and two metabolites, clethodim sulfoxide ((E, E)-(+/-)-2-[1-[[3-chloro-2-propenyl)oxy]imino]propyl]-5-[2-(ethylsulf inyl)propyl]-3-hydroxy-2-cyclohexen-1-one) and sethoxydim sulfoxide ((+/-)-2-[1-(ethoxyimino)butyl]-5-[2-ethylsulfinyl)propyl]-3 -hydroxy- 2-cyclohexen-1-one), in water by high-performance liquid chromatography/electrospray/mass spectrometry (LC/ES/MS) is reported. River water and distilled water were spiked at 0.08 and 0.8 microgram L(-1) with all three herbicides, which were then extracted from the water by C(18)-SPE (SPE = solid-phase extraction). The herbicides and metabolites were quantified and confirmed using selected ion monitoring. The percent recoveries of the herbicides from water spiked at 0.8 microgram L(-1) were as follows: alloxydim, 117 +/- 11%; clethodim, 96 +/- 14%; sethoxydim, 89 +/- 13%. There was no evidence of oxidation of clethodim and sethoxydim during the extraction to their respective sulfoxides. The limit of quantitation was <0.1 microgram L(-1). We have shown that we can analyze and confirm three cyclohexanedione oxime herbicides and two metabolites in water by LC/ES/MS. This multiresidue method should also be appropriate for other cyclohexanedione oximes.  相似文献   

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