首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
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.
The unique flavor of Oscypek, a Polish ewe's milk smoked cheese, is described as slightly sour, piquant, salted, and smoked. In this paper with the application of gas chromatography-olfactometry (GC-O) and combination of aroma extract dilution analysis (AEDA) 20 potent odorants of this cheese have been identified within the flavor dilution factor (FD) range of 4-2048. Among them, 2-methoxyphenol, 2-methoxy-4-methylphenol, 4-methylphenol, and butanoic acid showed the highest FD factors. Quantification results based on labeled standard addition followed by calculation of odor activity values (OAV) of 13 compounds with the highest FD factors revealed that 11 compounds were present at concentrations above their odor threshold values and therefore mostly contribute to the overall aroma of smoked ewe's milk cheese. Six of those compounds were represented by phenolic derivatives, with the highest OAV for 2-methoxyphenol (1280). Analysis of key odorants of an unsmoked cheese sample showed that the smoking process had a fundamental influence on Oscypek aroma formation.  相似文献   

3.
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   

4.
The effect on mycelial growth of the fungus Botrytis cinerea of a set of structurally related tricyclic hydroquinones [9,10-dihydroxy-4,4-dimethyl-2,3,5,8-tetrahydroantracen-1(4H)-one and 9,10-dihydroxy-4,4-dimethyl-5,8-dihydroanthracen-1(4H)-one derivatives] and tricyclic quinones [4,4-dimethylanthracen-1,9,10(4H)-trione derivatives] was studied. In general, the anthraquinones presented higher activity than the anthrahydroquinones. Anthraquinone and anthrahydroquinone derivatives with methyl groups on the A ring showed higher antifungal activity than the unsubstituted ones, 4,4,6,7-tetramethyl-(4H)-anthracene-1,9,10-trione being the most active compound of this set. The presence of a polar group such as hydroxymethyl reduced the activity. The effect of two anthrahydroquinones and two anthraquinones on the conidia germination of the fungus was also determined. Anthrahydroquinones did not affect the germination. The most active compound was 4,4-dimethylanthracene-1,9,10(4H)-trione, with 100% inhibition of germination at 7 h of incubation. These results again suggest that the structure of the anthraquinones is important in exerting an antifungal effect on B. cinerea. Furthermore, possible mechanisms of action of compound 4,4-dimethylanthracene-1,9,10(4H)-trione were studied. This compound did not produce lipoperoxidation of membrane and did not induce the formation of oxygen reactive species, but it was able to permeabilize the plasmatic membrane of B. cinerea, increasing the phosphorus concentration in the intracellular medium.  相似文献   

5.
Biotransformation of the environmental pollutant 3-methyl-4-nitrophenol (MNP), a newly characterized estrogenic chemical, and the primary breakdown product of the heavily used insecticide fenitrothion was investigated using a common soil fungus. In 96 h, daily culture sacrifice, extraction, and analysis showed that the filamentous fungus, Aspergillus niger VKM F-1119, removed more than 85% of the MNP present in solution (original concentration = 25 mg/L), mostly through biodegradation. Additionally, in 16-day time-course studies, A. niger was capable of biotransformation of MNP at concentrations as high as 70 mg/L. Gas chromatography mass spectroscopy (MS) analyses of culture fluid extracts indicated the formation of four metabolites: 2-methyl-1,4-benzenediol, 4-amino-3-methylphenol, and two singly hydroxylated derivatives of MNP. Culture scale up and metabolite analysis by liquid chromatography MS resulted in the confirmation of the original metabolites plus the detection of an azo derivative metabolite that has not been previously reported before during MNP biodegradation by any micro-organisms.  相似文献   

6.
The present study was carried out to investigate the modulating effects of thyme and its major components against the oxidative DNA damage induced by H(2)O(2). The human lymphocytes with thymol, carvacrol, and gamma-terpinene incubated with or without 0.1 mM H(2)O(2) for 30 min at 37 degrees C and the DNA damage were evaluated by singe cell gel electropheresis (comet assay). Concentrations above 0.1 mM thymol and gamma-terpinene and 0.05 mM carvacrol significantly induced DNA damage in human lymphocytes, but at the smaller concentrations no additional DNA strand breakage has been observed. At the all concentrations studied, gamma-terpinene did not show any protective effect against H(2)O(2) induced oxidative DNA damage, but the phenolic compounds thymol and carvacrol at concentrations below 0.2 and 0.1 mM, respectively, significantly reduced the oxidative DNA damage (p < 0.001). The n-hexane and ethyl acetate fractions prepared from the methanolic extracts of Thymus spicata also were found to inhibit DNA damage.  相似文献   

7.
为了更清晰地研究三大组分(纤维素、木聚糖、木质素)在介孔ZSM-5参与下的催化热解过程,该研究首先对生物质的三大基本组分和云南松木粉进行热解,然后在介孔ZSM-5催化剂存在的条件下对微晶纤维素、木聚糖、碱性木质素三大组分和云南松进行催化热解。采用气质联用仪对生物油的化学组分进行分析。通过对比ZSM-5参与前后的生物油的主要化学组分的变化,对催化剂的催化机理进行探究。研究结果表明,催化热解过程中,介孔ZSM-5将纤维素直接热解得到的β-D阿洛糖、糠醛、3-丙基戊二酸和2,4-戊二烯酸转化为1-甲基萘、2,6-二甲基萘,纤维素催化热解得到的生物油中的芳烃含量为63.89%。半纤维素催化热解过程中,催化剂将生物油中的糠醛从67.78%降低为2.66%,有效提高芳烃化合物,包括萘、2-甲基萘的含量,催化热解后得到的生物油中总芳烃含量达到36.81%。木质素催化热解过程中,介孔ZSM-5有效降低生物油中2,6-二叔丁基对甲酚的量(从82.33%降至77.97%),并大幅地提高1,8-二甲基萘和1,7-二甲基萘的量,生物油中总芳烃相对含量达到14.14%。云南松催化热解过程中,催化剂有效降低云南松直接热解得到生物油中2-甲氧基-4-甲基苯酚和(Z)-异丁子香酚的含量,并将芳烃化合物总量提高到53.99%(主要是1-甲基萘、1-亚甲基-1氢-茚和2,6-二甲基萘)。随着催化剂使用次数的增加,生物油中含氧化合物相对含量增加,烃类化合物的相对含量明显降低,从53.99%降至43.32%,元素分析结果表明生物油中的碳含量逐渐减少,氧含量逐渐增加。但是,催化剂经过焙烧再生后,催化活性基本完全恢复。  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.
The photodegradation of imazethapyr, 5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-4,5-dihydroimidazol-1H-3-yl)nicotinic acid, has been investigated in phosphate buffers and in buffered solutions containing natural organic matter (NOM). Imazethapyr degrades most quickly under 253.7 nm light and at pH values >4. The presence of NOM in solution caused the reaction rate constants for the photodegradation to decrease, with higher concentrations of NOM having a larger effect. Calculations suggest light screening is the major effect of the NOM. Seven photoproducts have been identified, and a photodegradation mechanism is proposed.  相似文献   

10.
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   

11.
Application of the aroma extract dilution analysis on an extract of white pepper powder showing an intense fecal, cowshed-like off-flavor revealed 3-methylindole (fecal, swine-manure) and 4-methylphenol (fecal, horse-like) with the highest flavor dilution (FD) factors among the 22 odor-active compounds detected. In addition, high FD factors and/or undesirable odor qualities suggested 3-methylphenol (phenolic), butanoic acid (cheese-like), and 2- and 3-methylbutanoic acid (cheese-like) as well as pentanoic acid and hexanoic acid (cheese-like odors) as contributors to the malodor. Although the intensities of the off-note were clearly different in 50 commercial samples of white pepper, quantitation of 3-methylindole and 3- and 4-methylphenol as well as of the five short-chain acids by means of stable isotope dilution assays showed similar concentrations in most of the samples. Storage of a freshly ground white pepper powder for up to 7 months revealed a significant decrease in the typical odor qualities of white pepper and an increase in the fecal odor note with storage time. Because the concentrations of the odorants mentioned above were not much changed during storage, possibly very volatile odorants, such as alpha-pinene, which are able to mask the malodor, are lost during storage of, in particular, pepper powders. On the basis of odor activity values, which were calculated using breakthrough thresholds, in particular, 3-methylindole, 4-methylphenol, 3-methylphenol, and butanoic acid could be suggested as the main sources of the fecal off-flavor.  相似文献   

12.
Application of the aroma extract dilution analysis (AEDA) on the volatile fraction carefully isolated from an American Bourbon whisky revealed 45 odor-active areas in the flavor dilution (FD) factor range of 32-4096 among which (E)-beta-damascenone and delta-nonalactone showed the highest FD factors of 4096 and 2048, respectively. With FD factors of 1024, (3S,4S)-cis-whiskylactone, gamma-decalactone, 4-allyl-2-methoxyphenol (eugenol), and 4-hydroxy-3-methoxy-benzaldehyde (vanillin) additionally contributed to the overall vanilla-like, fruity, and smoky aroma note of the spirit. Application of GC-Olfactometry on the headspace above the whisky revealed 23 aroma-active odorants among which 3-methylbutanal, ethanol, and 2-methylbutanal were identified as additional important aroma compounds. Compared to published data on volatile constituents in whisky, besides ranking the whisky odorants on the basis of their odor potency, 13 aroma compounds were newly identified in this study: ethyl (S)-2-methylbutanoate, (E)-2-heptenal, (E,E)-2,4-nonadienal, (E)-2-decenal, (E,E)-2,4-decadienal, 2-isopropyl-3-methoxypyrazine, ethyl phenylacetate, 4-methyl acetophenone, alpha-damascone, 2-phenylethyl propanoate, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, trans-ethyl cinnamate, and (Z)-6-dodeceno-gamma-lactone.  相似文献   

13.
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   

14.
Fusapyrone (1) and deoxyfusapyrone (2) are two 3-substituted-4-hydroxy-6-alkyl-2-pyrones isolated from Fusarium semitectum that have considerable antifungal activity against molds. Because of their low zootoxicity and selective action they are potentially utilizable along with biocontrol yeasts for control of postharvest crop diseases. Seven derivatives of 1 (3 and 5-10) and one derivative of 2 (4) were obtained by chemical modifications of the glycosyl residue, the 2-pyrone ring, the aliphatic chain, or a combination thereof, and a structure-activity correlation study was carried out with regard to their zootoxicity and antifungal activity. Derivatives 7-10, as well as 1, were slightly zootoxic in Artemia salina (brine shrimp) bioassays, whereas pentaacetylation of 1 into 3, 5, and 6 resulted in a strong increase in toxicity. Compound 4, the tetraacetyl derivative of 2, was as toxic as 2. Because the structural changes of 1 that resulted in an increase of biological activity in A. salina bioassay were those that affected mainly the water solubility of the molecule, it appears that toxicity is related to hydrophobicity. Compounds 1 and 2 showed strong antifungal activity toward Botrytis cinerea, Aspergillus parasiticus, and Penicilliun brevi-compactum (minimum inhibitory concentration at 24 h = 0.78-6.25 microg/mL). Among derivatives 3-10, only compounds 7, 9, and 10 retained some activity, limited to B. cinerea and at high concentration (25-50 microg/mL). None of the compounds 1-10 inhibited the growth of the biocontrol yeasts Pichia guilliermondii and Rhodotorula glutinis at the highest concentration tested (50 microg/mL).  相似文献   

15.
An L(16) (4(5)) orthogonal experimental design was used to evaluate combination effects of nitroethane (0-15 mM), 2-nitroethanol (0-15 mM), 2-nitro-1-propanol (0-15 mM), pyromellitic diimide (0-0.07 mM), and 2-bromoethanesulfonate (0-0.05 mM) on in vitro ruminal fermentation of a grain-rich feed. In vitro dry matter disappearance was adversely affected by these inhibitors, while cumulative gas production was not affected. Volatile fatty acid production was increased by nitroethane and 2-bromoethanesulfonate in a dose-dependent manner and was decreased by 2-nitroethanol and pyromellitic diimide. All inhibitor treatments increased the molar acetate proportion, while decreasing proportions of propionate and butyrate; hydrogen recovery was decreased by 36.9-45.2%; and methane production was reduced by 95.2-99.2%. The methanogenesis inhibition ranked: nitroethane > 2-nitroethanol > 2-nitro-1-propanol > 2-bromoethanesulfonate > pyromellitic diimide; combined concentrations of 5, 5, 5, 0.02, and 0.03 mM, respectively, gave the optimal inhibiting efficiency. These results may provide a reference to develop effective mitigation of methane emission from ruminants.  相似文献   

16.
Parasporal inclusion proteins produced by Bacillus thuringiensis strain A1470 exhibit strong cytotoxicity against human leukemic T cells when activated by protease treatment. One of the cytotoxic proteins was separated by anion exchange chromatography and gel filtration chromatography and designated Cry45Aa. Its gene was then expressed in recombinant Escherichia coli, in which the Cry45Aa precursor was accumulated in an inclusion body. It was solubilized in sodium carbonate buffer and processed with proteinase K, and cytotoxic activities of the protein against various mammalian cell lines were evaluated using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide assay. The protein exhibited high cytotoxic activity against CACO-2, Sawano, MOLT-4, TCS, and HL60 cells and moderate activity against U-937 DE-4, PC12, and HepG2 cells. On the other hand, the EC50 values against Jurkat, K562, HeLa, A549, Vero, COS-7, NIH3T3, CHO, and four normal tissue cells (human primary hepatocyte cells, UtSMC, MRC-5, and normal T cells) were >2 microg/mL.  相似文献   

17.
Enzymatically modified licorice extract (EMLE) is a natural sweetener, which is prepared with cyclodextrin glucanotransferase. It is used because of its unique properties such as higher solubility and better taste than those of licorice extract. In the present paper, the structures of six major constituents isolated from EMLE were determined, and their sweetness was studied. The isolated compounds were glycyrrhizin (1), 3-O-[beta-D-glucuronopyranosyl-(1-->2)-beta-D-glucuronopyranosyl]liquiritic acid (2), and their derivatives glucosylated at the C-4 position of the terminal glucuronopyranose with additional one (3 and 4, respectively) and two (5 and 6, respectively) glucose moieties. Compounds 1 and 2 are the major and minor sweet constituents in licorice extract, respectively. Compounds 3-6 are new compounds isolated for the first time. Compound 2 was sweeter than compound 1. Interestingly, compound 3, which is a monoglucosylated derivative of compound 1, was sweeter than compound 4. The sweetness of both compounds was lower than that of the parent compounds, while the lingering sweet aftertaste was markedly improved. Compounds 5 and 6, which have two additional glucose moieties, showed only slight sweetness.  相似文献   

18.
The concentrations of 19 odorants, recently characterized by GC-olfactometry and aroma extract dilution analysis as the most odor-active compounds in raw hazelnuts, were quantitated by stable isotope dilution assays (SIDA). Calculation of odor activity values (OAV) on the basis of odor thresholds in oil revealed high OAVs, in particular for linalool, 5-methyl-4-heptanone, 2-methoxy-3,5-dimethylpyrazine, and 4-methylphenol. A model mixture in sunflower oil containing the 13 odorants showing OAVs above 1 in their natural concentrations resulted in a good similarity compared to the overall nut-like, fruity aroma of the raw hazelnuts. Quantitation of the 25 most odor-active compounds in roasted hazelnut paste by SIDA showed clear changes in the concentrations of most odorants, and formation of new odor-active compounds induced by the roasting process was observed. The highest OAVs were calculated for 3-methylbutanal (malty), 2,3-pentanedione (buttery), 2-acetyl-1-pyrroline (popcorn), and (Z)-2-nonenal (fatty), followed by dimethyl trisulfide, 2-furfurylthiol, 2,3-butanedione, and 4-hydroxy-2,5-dimethyl-3(2H)-furanone. The aroma of a model mixture containing the 19 odorants with OAVs above 1 in their actual concentrations in the roasted nut material was judged to elicit a very good similarity to the popcorn-like, coffee-like, and sweet-smoky aroma of the roasted hazelnut paste. New SIDAs were developed for the quantitation of 5-methyl-4-heptanone, 5-methyl-(E)-2-hepten-4-one, 2-thenylthiol, and 3,5,5-trimethyl-2(5H)-furanone.  相似文献   

19.
Antifeedant effects of marine halogenated monoterpenes   总被引：4，自引：0，他引：4  
In this work the antifeedant effects of the halogenated monoterpenes 1-13 were tested against several divergent insect species. These compounds have been isolated from Plocamium cartilagineum (6 was isolated as an acetyl derivative), except for 4, which was isolated from Pantoneura plocamioides. We have also included the semisynthetic derivatives 1a, 2a, and 7. Compounds 1, 1a, 2, 4, 5, 7, 8-10, and 13 were antifeedants against Leptinotarsa decemlineata with varying potencies. The aphids Myzus persicae and Ropalosiphum padi were strongly deterred in the presence of compounds 2, 12, and 13. This effect was correlated with the electronic recording of their probing behavior. Compounds 2 and 12 were toxic to L. decemlineata and had selective cytotoxicity to insect-derived Sf9 cells. None of the tested compounds showed phytotoxic effects. The antifeedant and cytotoxic effects of these compounds were compared with those of the polyhalogenated insecticide gamma-hexachlorocyclohexane (lindane).  相似文献   

20.
The aim of the present study was to evaluate which structural elements of the vanillin molecule are responsible for its observed antifungal activity. MICs of vanillin, its six direct structural analogues, and several other related compounds were determined in yeast extract peptone dextrose broth against a total of 18 different food spoilage molds and yeasts. Using total mean MICs after 4 days of incubation at 25 degrees C, the antifungal activity order was 3-anisaldehyde (1.97 mM) > benzaldehyde (3.30 mM) > vanillin (5.71 mM) > anisole (6.59 mM) > 4-hydroxybenzaldehyde (9.09 mM) > phenol (10.59 mM) > guaiacol (11.66 mM). No correlation was observed between the relative antifungal activity of the test compounds and log P(o/w). Furthermore, phenol (10.6 mM) was found to exhibit a greater activity than cyclohexanol (25.3 mM), whereas cyclohexanecarboxaldehyde (2.13 mM) was more active than benzaldehyde (3.30 mM). Finally, the antifungal order of isomers of hydroxybenzaldehyde and anisaldehyde was found to be 2- > 3- > 4- and 3- > 2- > 4-, respectively. In conclusion, the aldehyde moeity of vanillin plays a key role in its antifungal activity, but side-group position on the benzene ring also influences this activity. Understanding how the structure of natural compounds relates to their antimicrobial function is fundamentally important and may help facilitate their application as novel food preservatives.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号