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1.
Cinnamon bark has been reported to be effective in the alleviation of diabetes through its antioxidant and insulin-potentiating activities. In this study, the inhibitory effect of cinnamon bark on the formation of advanced glycation endproducts (AGEs) was investigated in a bovine serum albumin (BSA)-glucose model. Several phenolic compounds, such as catechin, epicatechin, and procyanidin B2, and phenol polymers were identified from the subfractions of aqueous cinnamon extract. These compounds showed significant inhibitory effects on the formation of AGEs. Their antiglycation activities were not only brought about by their antioxidant activities but also related to their trapping abilities of reactive carbonyl species such as methylglyoxal (MGO), an intermediate reactive carbonyl of AGE formation. Preliminary study on the reaction between MGO and procyanidin B2 revealed that MGO-procyanidin B2 adducts are primary products which are supposed to be stereoisomers. This is the first report that proanthocyanidins can effectively scavenge reactive carbonyl species and thus inhibit the formation of AGEs. As proanthocyanidins behave in a similar fashion as aminoguanidine (AG), the first AGE inhibitor explored in clinical trials, they show great potential to be developed as agents to alleviate diabetic complications.  相似文献   

2.
A normal-phase HPLC-MS/MS method was applied to screen for proanthocyanidins in 88 different kinds of foods. Thirty-nine foods were found to contain proanthocyanidins. These foods include 19 kinds of fruits, eight cereals/beans, seven nuts, two beverages, two spices, and one vegetable. Twenty-five kinds of foods were found to contain both oligomeric (DP 10), and the other 14 foods contained only oligomers. Procyanidins with B-type linkages were detected as the only components in 21 foods and also as principal components in the others. Propelargonidins were identified in pinto bean, raspberry, strawberry, and almond, etc. Plum, avocado, peanut, curry, and cinnamon were identified as potential sources of A-type proanthocyanidins in addition to cranberry. Thiolytic degradation and MS/MS analyses indicated that the A-type linkages are present as a terminal unit in plum or between the extension units in curry, cinnamon, and avocado, whereas A-type linkages exist at both positions in cranberry and peanut.  相似文献   

3.
Coffee brew is a widely consumed beverage with multiple biological activities due both to naturally occurring components and to the hundreds of chemicals that are formed during the roasting process. Roasted coffee extract possesses antibacterial activity against a wide range of microorganisms, including Staphylococcus aureus and Streptococcus mutans, whereas green coffee extract exhibits no such activity. The naturally occurring coffee compounds, such as chlorogenic acids and caffeine, cannot therefore be responsible for the significant antibacterial activity exerted by coffee beverages against both bacteria. The very low minimum inhibitory concentration (MIC) found for standard glyoxal, methylglyoxal, and diacetyl compounds formed during the roasting process points to these alpha-dicarbonyl compounds as the main agents responsible for the antibacterial activity of brewed coffee against Sa. aureus and St. mutans. However, their low concentrations determined in the beverage account for only 50% of its antibacterial activity. The addition of caffeine, which has weak intrinsic antibacterial activity, to a mixture of alpha-dicarbonyl compounds at the concentrations found in coffee demonstrated that caffeine synergistically enhances the antibacterial activity of alpha-dicarbonyl compounds and that glyoxal, methylglyoxal, and diacetyl in the presence of caffeine account for the whole antibacterial activity of roasted coffee.  相似文献   

4.
Flavors and natural botanic extracts are often used in chewing gum and compressed mints for breath freshening and relief of oral malodor. The oral malodor is a result of bacterial putrification of proteinaceous materials from food or saliva. In this study, magnolia bark extract (MBE) and its two main components, magnolol and honokiol, were evaluated by the minimum inhibition concentration (MIC) test. The inhibitory effect of MBE mint was further evaluated by a kill-time assay study. In addition, an in vivo study was performed on nine healthy volunteers postlunch. Saliva samples were taken before and after subjects consumed mints and gum, with and without MBE. Listerine mouthwash was included as a positive control. The testing results indicated that MBE and its two main constituents demonstrated a strong germ-kill effect against bacteria responsible for halitosis and also Streptococcus mutans, bacteria involved in dental caries formation. The MIC of magnolol, honokiol, and MBE on Porphyromonas gingivalis, Fusobacterium nucleatum, and S. mutans ranged from 8 to 31 microg/mL. Kill-time assay results indicated that mints containing 0.2% MBE reduced more than 99.9% of three oral bacteria within 5 min of treatment. The in vivo study demonstrated that MBE containing mints reduced total salivary bacteria by 61.6% at 30 min and 33.8% at 60 min postconsumption. In comparison, the flavorless mint reduced total salivary bacteria by 3.6% at 30 min and increased total bacteria by 47.9% at 60 min. The MBE containing chewing gum reduced total salivary bacteria by 43.0% at 40 min, while placebo gum reduced total salivary bacteria by 18.0%. In conclusion, MBE demonstrated a significant antibacterial activity against organisms responsible for oral malodor and can be incorporated in compressed mints and chewing gum for improved breath-freshening benefits.  相似文献   

5.
The aim of the study presented here was to gain knowledge about the vapor-phase antimicrobial activity of selected essential oils and their major putatively active constituents against a range of foodborne bacterial and fungal strains. In a first step, the vapor-phase antimicrobial activities of three commercially available essential oils (EOs)-cinnamon (Cinnamomum zeylanicum), thyme (Thymus vulgaris), and oregano (Origanum vulgare)-were evaluated against a wide range of microorganisms, including Gram-negative bacteria (Escherichia coli, Yersinia enterocolitica, Pseudomonas aeruginosa, and Salmonella choleraesuis), Gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, and Enterococcus faecalis), molds (Penicillium islandicum and Aspergillus flavus), and a yeast (Candida albicans). The minimum inhibitory concentrations (MICs) were generally lower for oregano EO than for the thyme and cinnamon EOs, especially against the relatively resistant Gram-negative. The persistence of the EOs' antimicrobial activities over time was assessed, and changes in the composition of the atmosphere they generated over time were determined using single-drop microextraction (SDME) in combination with gas chromatography-mass spectrometry (GC-MS) and subsequent analysis of the data by principal component analysis (PCA). More relevant chemicals were selected. In addition, the vapor-phase activities of putatively key constituents of the oils were screened against representative Gram-positive (L. monocytogenes) and Gram-negative (S. choleraesuis) bacteria, a mold (A. flavus), and a yeast (C. albicans). Of the tested compounds, cinnamaldehyde, thymol, and carvacrol showed the strongest antimicrobial effectiveness, so their MICs, defined as the minimum vapor concentrations that completely inhibited detectable growth of the microorganisms, were calculated. To check for possible interactions between components present in the EOs, cinnamon EO was fortified with cinnamaldehyde and thyme EO with thymol, and then the antimicrobial activities of the fortified oils were compared to those of the respective unfortified EOs using fractional inhibitory concentration (FIC) indices and by plotting inhibition curves as functions of the vapor-phase concentrations. Synergistic effects were detected for cinnamaldehyde on A. flavus and for thymol on L. monocytogenes, S. choleraesuis, and A. flavus. In all other cases the fortification had additive effects, except for cinnamaldehyde's activity against S. choleraesuis, for which the effect was antagonistic. Finally, various microorganisms were found to cause slight changes over time to the atmospheres generated by all of the EOs (fortified and unfortified) except the fortified cinnamon EO.  相似文献   

6.
Geranium niveum S. Watson (Geraniaceae) is a medicinal herb widely used by the Tarahumara Indians of Mexico. This species is rich in proanthocyanidins and other phenolics. Previous in vitro assays have demonstrated that proanthocyanidins exhibited antiinflammatory, antiviral, antibacterial, enzyme-inhibiting, antioxidant, and radical-scavenging properties. In view of its medicinal use and chemical composition, the aim of the present study was to determine the in vitro antioxidant activity of the extracts and two proanthocyanidins (geranins A and D) from the roots of G. niveum by using seven different assay systems, namely, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion (O2*-), hydrogen peroxide (H2O2), hydroxyl radical (OH*), hypochlorous acid (HOCl), and singlet oxygen ((1)O2). Two known antioxidants, resveratrol and ascorbic acid, were used as positive controls. The results showed that geranins A and D and the extracts were able to scavenge ABTS, DPPH, O2*-, OH*, and HOCl. The scavenging ability of geranins A and D was similar to that of resveratrol and ascorbic acid in the following assays: ABTS, O2*-, and HOCl. The scavenging capacity of ascorbic acid for DPPH was higher than that of both geranins and resveratrol. On the other hand, the OH* scavenging action of both geranins and resveratrol was similar. The methanol-CHCl3 (1:1) extract had a higher ability to scavenge ABTS, DPPH, and O2*- radicals than the chloroform extract. In turn, the latter was more potent than the methanol-CHCl3 (1:1) extract as OH* or HOCl scavenger agent. Neither geranins A and D nor the extracts were able to scavenge H2O2 and (1)O2. In conclusion, G. niveum roots have proanthocyanidins with powerful radical scavenging in vitro activity. This property may partially explain the wide use of this plant in the Tarahumara indigenous system of medicine for the treatment of gastrointestinal illnesses (other than spasms), pain, and fevers associated with oxidative stress.  相似文献   

7.
The essential oil obtained from the bark of Cinnamomum zeylanicum Blume (Lauraceae) and three of its main components, eugenol, (E)-cinnamaldehyde, and linalool (representing 82.5% of the total composition), were tested in two in vitro models of peroxynitrite-induced nitration and lipid peroxidation. The essential oil and eugenol showed very powerful activities, decreasing 3-nitrotyrosine formation with IC50 values of 18.4 microg/mL and 46.7 microM, respectively (reference compound, ascorbic acid, 71.3 microg/mL and 405.0 microM) and also inhibiting the peroxynitrite-induced lipid peroxidation showing an IC50 of 2.0 microg/mL and 13.1 microM, respectively, against 59.0 microg/mL (235.5 microM) of the reference compound Trolox. On the contrary, (E)-cinnamaldehyde and linalool were completely inactive.  相似文献   

8.
Hippomarathrum microcarpum grows wild in eastern Anatolia, Turkey, and is a plant utilized as food by people. In this study, the in vitro antimicrobial and antioxidant activities of the essential oil and methanol extract from H. microcarpum and its essential oil composition were investigated. The essential oil, which has bornyl acetate, caryophyllene oxide, and beta-caryophyllene as its main components, exhibited activity against eight bacteria, nine fungi, and a yeast, Candida albicans, with minimum inhibitory concentration values ranging from 62.50 to 125 muL/mL; the methanol extract showed weak activity. The antioxidant activity of these extracts was assessed by the beta-carotene bleaching test and the 1,1'-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging test. The inhibition of linoleic acid oxidation was very weak for both extracts tested. The inhibition percentages were found to be 22.9 and 33.5% for methanol and essential oil, respectively, at the concentration of 2 g/L. The oil scavenged DPPH at higher concentrations (IC50 = 10.69 +/- 0.05 mg/mL), but the methanol extract exhibited no activity. The total phenolic content of the methanol extract was found to be 4.7 +/- 0.1%.  相似文献   

9.
We evaluated 17 plant essential oils and nine oil compounds for antibacterial activity against the foodborne pathogens Escherichia coli O157:H7 and Salmonella enterica in apple juices in a bactericidal assay in terms of % of the sample that resulted in a 50% decrease in the number of bacteria (BA(50)). The 10 compounds most active against E. coli (60 min BA(50) range in clear juice, 0.018-0.093%) were carvacrol, oregano oil, geraniol, eugenol, cinnamon leaf oil, citral, clove bud oil, lemongrass oil, cinnamon bark oil, and lemon oil. The corresponding compounds against S. enterica (BA(50) range, 0.0044-0.011%) were Melissa oil, carvacrol, oregano oil, terpeineol, geraniol, lemon oil, citral, lemongrass oil, cinnamon leaf oil, and linalool. The activity (i) was greater for S. enterica than for E. coli, (ii) increased with incubation temperature and storage time, and (iii) was not affected by the acidity of the juices. The antibacterial agents could be divided into two classes: fast-acting and slow-acting. High-performance liquid chromatography analysis showed that the bactericidal results are related to the composition of the oils. These studies provide information about new ways to protect apple juice and other foods against human pathogens.  相似文献   

10.
European, small-fruited cranberries (Vaccinium microcarpon) and lingonberries (Vaccinium vitis-idaea) were characterized for their phenolic compounds and tested for antioxidant, antimicrobial, antiadhesive, and antiinflammatory effects. The main phenolic compounds in both lingonberries and cranberries were proanthocyanidins comprising 63-71% of the total phenolic content, but anthocyanins, hydroxycinnamic acids, hydroxybenzoic acids, and flavonols were also found. Proanthocyanidins are polymeric phenolic compounds consisting mainly of catechin, epicatechin, gallocatechin, and epigallocatechin units. In the present study, proanthocyanidins were divided into three groups: dimers and trimers, oligomers (mDP 4-10), and polymers (mDP > 10). Catechin, epicatechin, A-type dimers and trimers were found to be the terminal units of isolated proanthocyanidin fractions. Inhibitions of lipid oxidation in liposomes were over 70% and in emulsions over 85%, and in most cases the oligomeric or polymeric fraction was the most effective. Polymeric proanthocyanidin extracts of lingonberries and cranberries were strongly antimicrobial against Staphylococcus aureus, whereas they had no effect on other bacterial strains such as Salmonella enterica sv. Typhimurium, Lactobacillus rhamnosus and Escherichia coli. Polymeric fraction of cranberries and oligomeric fractions of both lingonberries and cranberries showed an inhibitory effect on hemagglutination of E. coli, which expresses the M hemagglutin. Cranberry phenolic extract inhibited LPS-induced NO production in a dose-dependent manner, but it had no major effect on iNOS of COX-2 expression. At a concentration of 100 μg/mL cranberry phenolic extract inhibited LPS-induced IL-6, IL-1β and TNF-α production. Lingonberry phenolics had no significant effect on IL-1β production but inhibited IL-6 and TNF-α production at a concentration of 100 μg/mL similarly to cranberry phenolic extract. In conclusion the phenolics, notably proanthocyanidins (oligomers and polymers), in both lingonberries and cranberries exert multiple bioactivities that may be exploited in food development.  相似文献   

11.
Grape seed extract provides a concentrated source of polyphenols, most of which are proanthocyanidins. Polymeric proanthocyanidins are poorly absorbed in the small intestine of humans, and exposure may result from metabolism to phenolic acids by colonic bacteria. Any biological effects of proanthocyanidins may be due to the phenolic acid metabolites. Several phenolic acids have been identified as proanthocyanidin metabolites, but these may be derived from a range of other dietary sources. The aim of this study was to determine if 24-h urinary excretion of specific phenolic acids increased significantly and consistently following regular supplementation with grape seed extract. In a randomized, double-blind placebo-controlled trial, 69 volunteers received grape seed extract (1000 mg/day total polyphenols) or placebo for 6 weeks. Supplementation with grape seed polyphenols resulted in a consistent increase in the excretion of 3-hydroxyphenylpropionic acid (3-HPP, P < 0.001) and 4-O-methylgallic acid (P < 0.001) and a less consistent increase in the excretion of 3-hydroxyphenylacetic acid (P = 0.002). The observed increase in 3-HPP is in line with the suggestion that this compound is a major phenolic acid breakdown product of proanthocyanidin metabolism in vivo.  相似文献   

12.
Seasonal variation in chemical composition of essential oils obtained from Satureja parnassica subsp. parnassica Heldr. & Sart ex Boiss. and Satureja thymbra L. was determined by GC and GC-MS analysis. The in vitro antibacterial activities of these essential oils were evaluated at two different initial levels against two common foodborne bacteria. Their minimum inhibitory concentration (MIC) and noninhibitory concentration (NIC) values were determined via an innovative automated technique, which was applied on a Malthus apparatus combining the conductance measurements with the common dilution method. The essential oil concentration fluctuated greatly during the period examined and established that the Satureja oils obtained during the flowering period were the most potent, exhibiting the lowest MIC values and retaining remarkable bactericidal properties. Thus, they represent an inexpensive source of natural antibacterial substances that exhibit potential for use in food systems to prevent the growth of foodborne bacteria and to extend the shelf life of the processed food.  相似文献   

13.
The essential oil from the gum of Pistachio (Pistacia vera L. (Anacardiaceae)) grown in Turkey was obtained by the hydro-distillation method, and its chemical composition was analyzed by GC and GC-MS. Moreover, the antimicrobial activities of the oil against the growth of 13 bacteria and 3 pathogenic yeasts were evaluated using the agar-disk diffusion and minimum inhibitory concentration (MIC) methods. The results showed that the essential oil contained about 89.67% monoterpenes, 8.1% oxygenated monoterpenes and 1.2% diterpenes. alpha-Pinene (75.6%), beta-pinene (9.5%), trans-verbenol (3.0%), camphene (1.4%), trans-pinocarveol (about 1.20%), and limonene (1.0%) were the major components. The antimicrobial results showed that the oil inhibited nine bacteria and all the yeasts studied, and the activities were considerably dependent upon concentration and its bioactive compounds such as carvacrol, camphene, and limonene. Moreover, the essential oil of the gum was found to be more effective yeastcide than Nystatin, synthetic yeastcide. Furthermore, the antibacterial activities of the oil were lower than those of standard antibiotics, ampicillin sodium, and streptomycine sulfate under the conditions studied.  相似文献   

14.
我国大蒜废弃物资源丰富,为引导其合理化、资源化利用,测定了大蒜提取物对大豆尖孢镰刀菌（Fusarium oxysporum fsp.tracheiphilum）、油菜菌核病菌（Sclerotinia sclerotiorum（Lib.）d eBary）、大豆细菌性斑点病菌（Pseudomonas.s yringae pv.glycinea）和水稻白叶枯病菌（Xanthomonas oryzae pv.oryzae〔Ishiyama〕Dye,Xoo）4种植物病原菌的抑制作用,并通过大蒜提取物、大蒜渣、大蒜肥对土壤中大豆尖孢镰刀菌的抑制试验,测定了其在土壤中对土传病原菌的抑制效果。结果表明,高浓度的大蒜提取物对这4种植物病原菌有抑制作用,随着提取物浓度的升高,抑菌效果也更为明显。质量浓度为500mg.mL-1时对大豆尖孢镰刀菌、大豆细菌性斑点病菌和水稻白叶枯病菌的抑菌效果最好。培养基中提取物浓度达100mg.mL-1时对两种真菌的抑制达100%。同时,含大蒜提取物0.05mL.g-1、大蒜渣5%或大蒜肥25%的土壤能抑制土传病原菌大豆尖孢镰刀菌在土壤中的定殖。  相似文献   

15.
Pistacia vera L. is the only species of Pistacia genus producing edible nuts. This paper investigates the antioxidant potential of a Sicilian variety of pistachio nut by chemical as well as biological assays and measured antioxidant vitamins and a number of antioxidant polyphenols in either the hydrophilic and/or the lipophilic nut extract. In accordance with the majority of foods, the total antioxidant activity, measured as a TAA test, was much higher (50-fold) in the hydrophilic than in the lipophilic extract. Substantial amounts of total phenols were measured. The hydrophilic extract inhibited dose-dependently both the metal-dependent and -independent lipid oxidation of bovine liver microsomes, and the Cu+2-induced oxidation of human low-density lipoprotein (LDL). Peroxyl radical-scavenging as well as chelating activity of nut components may be suggested to explain the observed inhibition patterns. Among tocopherols, gamma-tocopherol was the only vitamin E isomer found in the lipophilic extract that did not contain any carotenoid. Vitamin C was found only in a modest amount. The hydrophilic extract was a source of polyphenol compounds among which trans-resveratrol, proanthocyanidins, and a remarkable amount of the isoflavones daidzein and genistein, 3.68 and 3.40 mg per 100 g of edible nut, respectively, were evaluated. With the exception of isoflavones that appeared unmodified, the amounts of other bioactive molecules were remarkably reduced in the pistachio nut after roasting, and the total antioxidant activity decreased by about 60%. Collectively, our findings provide evidence that the Sicilian pistachio nut may be considered for its bioactive components and can effectively contribute to a healthy status.  相似文献   

16.
为了研究蒲公英不同部位抑菌作用和代谢物成分的差异,本物采用打孔法和超高效液相色谱串联质谱(UPLC-MS/MS)方法,研究了蒲公英根、茎叶和花的水提取物和醇提取物对5种致病菌的抑菌作用,并对不同部位的代谢物成分进行了定性和定量分析。结果表明,蒲公英不同部位初提取物对变形杆菌、嗜根考克氏菌和枯草芽孢杆菌均有抑菌作用,而对大肠杆菌和铜绿假单胞菌均无抑菌作用;醇提法的抑菌效果优于水提法,花提取物的抑菌活性最强,根最弱。蒲公英的不同部位共鉴定出449种代谢物,根、茎叶和花中相对含量最高的物质分别为反油酸(脂类)、γ-亚麻酸(脂类)和木犀草素(黄酮类);且根、茎叶和花中相对含量排名前20的物质中黄酮类分别有0种、3种和8种,表明黄酮类物质可能是蒲公英中的主要抑菌活性物质。正交偏最小二乘法-判别分析(OPLS-DA)结果显示,木犀草素-7-O-葡萄糖苷在花中上调幅度最大,橙皮素C-丙二酰己糖苷为根中特有物质。本研究结果为利用蒲公英不同部位研制和开发新型药物提供了理论依据。  相似文献   

17.
Grape seeds accumulate in huge quantities as byproduct during wine production and are therefore a cheap source for pharmacologically active agents. However, studies prove poor antibacterial activity, and results of analyses are sometimes contradictory. The aim of this study was, thus, to determine the antibacterial activity of grape seed extracts with special focus on the chromatographic characterization of active fractions. In the course of these investigations, extraction protocols were optimized so that microwave-assisted extraction (MAE) guaranteed highest preconcentration efficiency. Proanthocyanidins, monomeric flavonoid aglycones, as well as some of their glycosides could be identified within yielded extracts via high-performance liquid chromatography-mass spectrometry (HPLC-MS). By that means the coherence number of possible isomers of procyanidins was approximated by a newly developed equation. As far as antibacterial activity determined via screening tests is concerned, the extracts generally have been found to be positively responsive toward 10 different gram-positive and gram-negative bacteria strains. After fractionation of the raw extracts, proanthocyanidins P2, P3, P4 and gallate esters P2G and P3G (P = proanthocyanidin consisting of catechin and epicatechin units, n = oligomerization degree, G = gallate ester) were determined as active antibacterial agents toward 10 different pathogens. Only moderate activity was found for monomeric flavonoid fractions.  相似文献   

18.
Curcumin is a highly potent, nontoxic, bioactive agent found in turmeric and has been known for centuries as a household remedy to many ailments. The only disadvantage that it suffers is of low aqueous solubility and poor bioavailability. The aim of the present study was to develop a method for the preparation of nanoparticles of curcumin with a view to improve its aqueous-phase solubility and examine the effect on its antimicrobial properties. Nanoparticles of curcumin (nanocurcumin) were prepared by a process based on a wet-milling technique and were found to have a narrow particle size distribution in the range of 2-40 nm. Unlike curcumin, nanocurcumin was found to be freely dispersible in water in the absence of any surfactants. The chemical structure of nanocurcumin was the same as that of curcumin, and there was no modification during nanoparticle preparation. A minimum inhibitory concentration of nanocurcumin was determined for a variety of bacterial and fungal strains and was compared to that of curcumin. It was found that the aqueous dispersion of nanocurcumin was much more effective than curcumin against Staphylococcus aureus , Bacillus subtilis , Escherichia coli , Pseudomonas aeruginosa , Penicillium notatum , and Aspergillus niger . The results demonstrated that the water solubility and antimicrobial activity of curcumin markedly improved by particle size reduction up to the nano range. For the selected microorganisms, the activity of nanocurcumin was more pronounced against Gram-positive bacteria than Gram-negative bacteria. Furthermore, its antibacterial activity was much better than antifungal activity. The mechanism of antibacterial action of curcumin nanoparticles was investigated by transmission electron micrograph (TEM) analysis, which revealed that these particles entered inside the bacterial cell by completely breaking the cell wall, leading to cell death.  相似文献   

19.
We investigated the antibacterial activity of some new 2-aryl-3,5-dimethoxy-1,4-benzoquinone derivatives, previously prepared from 2,6-dimethoxy-1,4-benzoquinone by Suzuki cross-coupling reactions, to find effective antibacterial agents. The antibacterial activity was first tested in vitro by the disk diffusion assay against two gram-positive and two gram-negative bacteria, and then the minimum inhibitory concentration (MIC) of active compounds was determined. The results showed that some 2-aryl-3,5-dimethoxy-1,4-benzoquinone derivatives inhibit growth of both gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes), microorganisms that cause food poisoning and rheumatic fever. This study points out the antibacterial activity of some 2-aryl-3,5-dimethoxy-1,4-benzoquinone derivatives.  相似文献   

20.
A method was developed for the fractionation of grape (seed or skin) proanthocyanidins according to their degree of polymerization. After precipitation in chloroform/methanol (75:25, v/v), the grape proanthocyanidins were deposited onto an inert glass powder column and sequentially dissolved in several fractions by increasing proportions of methanol in the solvent. Each fraction from each proanthocyanidin source was quantified and characterized after acidic degradation with phenylmethanethiol (i.e., thiolysis). The comparison of data from total extract and successive fractions showed that a quantitative separation was achieved so that estimation of polymer size distribution in relation to other compositional characteristics (proportions of prodelphinidin units, galloylation rate) was thus possible. Mean degree of polymerization of separated proanthocyanidins ranged increasingly from 4.7 to 17.4 in seed (8.1 for total extract) and from 9.3 to 73.8 in skin (34.9 for total extract). The method proposed is very interesting for the study of grape proanthocyanidins according to their degree of polymerization because it gives both qualitative and quantitative information especially on the highly polymerized forms, which were not fractionated by previous techniques.  相似文献   

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