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1.
In this work, we present a computational investigation on the reactions between two well-known antioxidants (quercetin and morin) and 2,2-diphenyl-1-picrylhydrazyl (DPPH). A density functional theory (DFT) approach with the B3LYP functional and the 6-31G(d,p) basis set was used for the simulations. The structural and energetic parameters (Gibbs free-energy, ΔG, and Gibbs free-energy of activation, ΔG++) were determined to provide information on the antioxidant activity as well as to evaluate the contributions of each hydroxyl group to the referred property. According to the results obtained, quercetin presented three hydroxyls as being thermodynamically spontaneous in the reaction with DPPH (4\(^{\prime }\)-ArOH, 3\(^{\prime }\)-ArOH, and 3-ArOH, with ΔG = -4.93 kcal/mol, -2.89 kcal/mol, and -1.87 kcal/mol, respectively) against only two in the case of morin (2\(^{\prime }\)-ArOH and 3-ArOH, with ΔG = -7.56 kcal/mol and -4.57 kcal/mol, respectively). Hence, quercetin was found to be a more efficient antioxidant, which is in agreement with different experimental and computational investigations of bond dissociation enthalpies (BDEs). However, the order of contribution of the OH groups of each compound to the antioxidant potential present some differences when compared to what was seen in the previous investigations, especially for morin. These findings are in contrast to what was observed in studies based on the determinations of BDEs. Therefore, experimental investigations on the hydrogen-atom transfer mechanism (HAT) for both compounds are encouraged in order to clarify these observations. 相似文献
2.
The pathways of the reaction of 2,2-diphenyl picrylhydrazyl radicals (DPPH) with (+)-catechin were studied in alcoholic solvents. The reaction mixtures were analysed by using reversed-phase liquid chromatography (HPLC) and electrospray ionization mass spectrometry (ESI-MS). The intermediate o-quinone of catechin, yellow dimers, trimers and, interestingly, an adduct of the oxidized form of catechin with DPPH radicals were identified. The mass of this adduct was 681 Da, suggesting that one molecule of the DPPH radical complexes with the oxidized form of catechin. It is concluded that once the intermediate o-quinone is formed, the reaction proceeds in two pathways, either the o-quinone reacts with catechin to form a hydrophilic dimer (type B), which is further oxidized to hydrophobic dimers (type A) and consequently to oligomers of higher molecular weights; or the A-ring of the o-quinone is further oxidized by a DPPH radical and that this oxidized intermediate then reacts with another DPPH radical to form the observed adduct. The identification of the latter mechanism could explain the contradictory results reported in the literature for the reaction of polyphenols with DPPH radicals. 相似文献
3.
Xie C Koshino H Esumi Y Onose J Yoshikawa K Abe N 《Bioorganic & medicinal chemistry letters》2006,16(20):5424-5426
A novel dibenzofuran compound designated vialinin B was isolated from dry fruiting bodies of an edible mushroom, Thelephora vialis, and potently inhibits TNF-alpha production in RBL-2H3 cells (IC(50)=0.02nM) and is a promising anti-allergic agent. 相似文献
4.
Santosh Kumar S Priyadarsini KI Sainis KB 《Redox report : communications in free radical research》2002,7(1):35-40
Vanillin, a plant derived natural product, used as food flavoring agent and its positional isomer o-vanillin, have been tested for their ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical using high performance liquid chromatography (HPLC). Trolox, a water-soluble analogue of vitamin E and a well-known antioxidant was used as a reference compound. The DPPH radical was monitored at 517 nm and its retention time was 8.6 min. From the decrease in optical density of DPPH radical in the presence of the test compounds, it was observed that o-vanillin was a more effective scavenger than vanillin. At equimolar concentrations (1 mM), vanillin and o-vanillin exhibited 22.9% and 66.4% DPPH radical scavenging activity, respectively. The kinetics of the reaction of vanillin and o-vanillin with DPPH radical was studied using stopped flow spectrophotometry and their rate constants were estimated to be 1.7 +/- 0.1 M(-1)s(-1) and 10.1 +/- 0.8 M(-1)s(-1), respectively. In comparison, the rate constant for the reaction of trolox with DPPH was estimated to be 360.2 +/- 10.1 M(-1)s(-1). These scavenging reactions involve electron/H-atom transfer from antioxidant to DPPH. To confirm this, one electron reduction potentials of these compounds were estimated using cyclic voltammetry which showed that o-vanillin was more easily oxidized than vanillin. The reduction potential for o-vanillin was about 1.5 times that of trolox. These results demonstrate that o-vanillin is a more potent antioxidant than vanillin. 相似文献
5.
Pakhale SS Karibasappa GS Ramchandani AG Bhushan B Sharma A 《Indian journal of experimental biology》2007,45(11):968-973
Antioxidant potency of Indian grape cultivars varying in their skin color, seed and polyphenol content (Bangalore blue, Pandhari sahebi, Sharad seedless and Thompson seedless) and their components (whole grapes, pulp with skin and seeds) was examined as 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity using electron spin resonance spectrometry. The total polyphenols in Indian grapes ranged between 3-51%. Extracted polyphenols caused a concentration dependent and significant loss in DPPH radical signal, similar to known antioxidants-Vitamin C, catechin and procyanidin B3 used as references. Among seedless cultivars, polyphenols from Sharad was more potent as antioxidant than Thompson, showing IC50 values of 1250 +/- 30 and 2650 +/- 125 microg/ml, respectively. The inhibitory effect of polyphenols from seedless grape cultivars was as effective as that of seeded variety. The results indicate that polyphenols extracted from Indian grapes/ components (with /without seeds) exhibited free radical scavenging activity and their chemopreventive properties need to be exploited by in vivo model system. 相似文献
6.
Sde Viirlaid Riina Mahlapuu Kalle Kilk Aleksei Kuznetsov Ursel Soomets Jaak Jrv 《Bioorganic chemistry》2009,37(4):126-132
Kinetic mechanism and stoichiometry of scavenging the 2,2-diphenyl-1-picrylhydrazyl radical by glutathione and its novel analog, containing α-glutamyl residue in place of the γ-glutamyl moiety, were studied using different ratios of reagents. At low concentrations of the peptides, the process was described as a bimolecular reaction obeying the stoichiometric ratio 1:1. However, at excess of peptides the formation of a non-covalent complex between the reagents was discovered and characterized by dissociation constants K = 0.61 mM for glutathione and K = 0.27 mM for the glutathione α-glutamyl analog, respectively. The complex formation was followed by a reaction step that was characterized by the similar rate constant k = 0.02 s−1 for both peptides. Thus, the apparently different antioxidant activity of these two peptides, observed under common assay conditions, was determined by differences in the formation of this non-covalent complex. 相似文献
7.
Akiko Komatsu Hideki Kondo Masayuki Sato Atsushi Kurahashi Kozo Nishibori Nobuhiro Suzuki Fumihiro Fujimori 《Mycoscience》2019,60(4):211-220
Grifola frondosa (Maitake mushroom) is an important cultivated mushroom due to its medicinal and nutrient values. In this study, we isolated and characterized a novel partitivirus (named Grifola frondosa partitivirus 1, GfPV1) infecting a standard G. frondosa strain Gf-N2. This virus has a two-segmented dsRNA genome (dsRNA1 and dsRNA2) with nucleotide lengths of 2.3 and 2.2 kbp, respectively. The coding strand of dsRNA1 and dsRNA2 segments carries single open reading frame encoding RNA-dependent RNA polymerase (RdRp) and a coat protein (CP), respectively. BLAST searches and phylogenetic analyses showed that GfPV1 is most closely related to a betapartitivirus, Lentinula edodes partitivirus 1 (RdRp <70% and CP <60% amino acid sequence identities), but the sequence divergence suggests that GfPV1 is classifiable as a new member of the genus Betapartitivirus, family Partitiviridae. The presence of GfPV1 does not affect colony morphology and fruiting body development of G. frondosa. This is the first report investigating the effects of a mycovirus infection on the colony morphology and fruiting body development of G. frondosa. Interestingly, GfPV1 accumulations markedly decreased along with the fruiting body maturation stages, suggesting the inhibition of virus multiplication during sexual phase of the G. frondosa life cycle. 相似文献
8.
A water-insoluble glucan, TEINS has been isolated from the hot alkaline extract of an edible mushroom Termitomyces eurhizus. The total carbohydrate content of the polysaccharide fraction was found to be 98.4%, and it was found to contain only glucose as the monosaccharide constituent. On the basis of total acid hydrolysis, a methylation experiment, periodate oxidation and (13)C NMR experiment, the repeating unit of the polysaccharide was established as: -->3)-beta-D-Glcp-(1-->. 相似文献
9.
A glucan that was soluble in aqueous sodium chloride was isolated from the aqueous extract of the fruiting bodies of Pleurotus florida. On the basis of total hydrolysis, methylation analysis, periodate oxidation, Smith degradation, and NMR studies (1H, 13C, TOCSY, DQF-COSY, NOESY, and HSQC), the structure of the repeating unit of the polysaccharide is established as: This glucan stimulates the phagocytic activity of macrophages. 相似文献
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12.
Mohamad H Abas F Permana D Lajis NH Ali AM Sukari MA Hin TY Kikuzaki H Nakatani N 《Zeitschrift für Naturforschung. C, Journal of biosciences》2004,59(11-12):811-815
The methanol extract of the dried ripe fruits of Alpinia rafflesiana was investigated for its DPPH free radical scavenger constituents. 2',3',4',6'-Tetrahydroxychalcone (7), which has never been isolated from natural sources was found to be most active as a DPPH free radical scavenger with the IC50 value of 55 microM. Other known compounds isolated from this species include 5,6-dehydrokawain (1), flavokawin B (2). 1,7-diphenyl-5-hydroxy-6-hepten-3-one (3), (-)-pinocembrin (4), cardamonin (5) and (-)-pinostrobin (6). The DPPH free radical scavenger compounds were detected using TLC autographic analysis. The percentage inhibition of DPPH free radical scavenging activity was measured on isolates (5-7) using colorimetric analysis. 相似文献
13.
A water-soluble glucan, Fraction I, was isolated from the aqueous extract of the fruit bodies of the mushroom Astraeus hygrometricus. On the basis of total hydrolysis, methylation analysis, periodate oxidation, and NMR studies ((1)H, (13)C, 2D-COSY, TOCSY, NOESY, and HSQC), the structure of the repeating unit of the glucan is determined as:This glucan shows strong splenocyte activation. 相似文献
14.
Kawagishi H Suzuki H Watanabe H Nakamura H Sekiguchi T Murata T Usui T Sugiyama K Suganuma H Inakuma T Ito K Hashimoto Y Ohnishi-Kameyama M Nagata T 《Biochimica et biophysica acta》2000,1474(3):299-308
In an experiment in which rats were allowed free access to food and water, the rats did not eat the diet containing a mushroom Pleurotus ostreatus even if they were emaciated. A P. ostreatus lectin (POL) was isolated from the mushroom as the food intake-suppression principle. In hemagglutination inhibition assays, Me-alphaGalNAc was the most potent inhibitor among the monosaccharides tested. Among all the sugars tested, 2'-fucosyllactose (Fucalpha1-->2Galbeta1-->4Glc) was the strongest inhibitor and its inhibitory potency was five times greater than that of Me-alphaGalNAc. POL exhibited a binding ability to bovine submaxillary mucin (BSM) and asialo-BSM and the other glycoproteins were inert to the binding. The food intake-suppressing activity of POL was dependent on the dose. The diet containing 0.1% POL caused a 50% decrease in the food intake of rats against the control. 相似文献
15.
Eryngin, a novel antifungal peptide from fruiting bodies of the edible mushroom Pleurotus eryngii 总被引:3,自引:0,他引:3
An antifungal peptide with a molecular mass of 10k Da was isolated from fruiting bodies of the mushroom Pleurotus eryngii. The peptide, designated as eryngin, inhibited mycelial growth in Fusarium oxysporum and Mycosphaerella arachidicola. It was unadsorbed on DEAE-cellulose and adsorbed on Affi-gel blue gel and S-Sepharose. Its N-terminal sequence demonstrated some similarity to the antifungal protein from the mushroom Lyophyllum shimeiji and little resemblance to thaumatin and thaumatin-like proteins. 相似文献
16.
Luis M. López-Martínez Hisila Santacruz-Ortega Rosa-Elena Navarro Rogerio R. Sotelo-Mundo Gustavo A. González-Aguilar 《PloS one》2015,10(11)
The benefits of phenolic acids on human health are very often ascribed to their potential to counteract free radicals to provide antioxidant protection. This potential has been attributed to their acidic chemical structure, which possesses hydroxyl groups in different positions. Phenolic acids can interact between themselves and exhibit an additive, antagonistic or synergistic effect. In this paper, we used 1H NMR to analyze the interactions and mechanisms that are present in major phenolic acids found in mango (gallic, protocatechuic, chlorogenic and vanillic acids) and papaya (caffeic, ferulic and p-coumaric acids), and the DPPH radical was used to evaluate the effect of the antioxidant mixtures. The interactions were found to occur via hydrogen bonds between the -OH and -COOH groups. Moreover, the phenolic acids exhibit two types of mechanisms for the neutralization of the DPPH radical. According to the results, these two mechanisms are Hydrogen Atom Transfer (HAT) and Single Electron Transfer (SET). The ability of the phenolic acid to neutralize the DPPH radical decreases in the following order in mango: gallic > chlorogenic > protocatechuic > vanillic. Moreover, within the acids found in papaya, the order was as follows: caffeic > p-coumaric > ferulic. 相似文献
17.
A ribonuclease with a temperature optimum of about 70 degrees C and a pH optimum of 6.5 was isolated from fruiting bodies of the mushroom Pleurotus eryngii. The ribonuclease was unadsorbed on DEAE-cellulose and adsorbed on Affi-gel blue gel and S-Sepharose. It possessed a molecular mass of 16 kDa, and exhibited higher ribonucleolytic activity toward poly A and poly G and lower ribonucleolytic activity toward poly C and poly U. Its N-terminal sequence was distinctly different from those of other mushroom ribonucleases, and resembled that of Pleurotus tuber-regium only by 40%. Furthermore, its thermostability characteristics, polyhomoribonucleotide specificity and molecular mass were dissimilar to those of other mushroom ribonucleases. 相似文献
18.
A fibrinolytic metalloprotease from the fruiting bodies of an edible mushroom, Armillariella mellea 总被引:3,自引:0,他引:3
A fibrinolytic metalloprotease has been purified from the fruiting bodies of the edible honey mushroom (Armillariella mellea). The enzyme has a molecular weight of 18538.1508, as measured by MALDI-TOF mass spectrometry and includes Zn2+ ion as found by ICP/MS. The N-terminal amino acid sequence, XXYNGXTXSRQTTLV, do not match any known protein or open reading frame. It hydrolyzes fibrinogen as well as fibrin, but does not show any proteolytic activity for other blood proteins such as thrombin, human albumin, bovine albumin, human IgG, hemoglobin, or urokinase. This protease hydrolyzes both A alpha and B beta subunits of human fibrinogen with equal efficiency. The enzyme activity was strongly inhibited by EDTA and 1,10-phenanthroline, indicating that the enzyme is a metalloprotease. No inhibition was found with PMSF, E-64, pepstatin, and 2-mercaptoethanol. The activity of the purified enzyme was slightly increased by Mg2+, Zn2+, and Co2+, but the enzyme was totally inhibited by Hg2+. It has broad substrate specificity for synthetic peptides, and a pH optimum at 7, suggested that the purified enzyme was a neutral protease. It was thermally stable up to 60 degrees C and the maximum fibrinolytic activity was at 55 degrees C. 相似文献
19.
A water-soluble polysaccharide was isolated from Fraction-II of the aqueous extract of the fruit bodies of the mushroom, Pleurotus florida. Compositional analysis, methylation analysis, periodate oxidation study, Smith degradation, and NMR studies (1H, 13C, DQF-COSY, TOCSY, NOESY, HSQC, and HMBC) revealed the presence of the following repeating unit in the polysaccharide: [structure: see text]. 相似文献
20.
Chemical analysis of a new fucoglucan isolated from an edible mushroom, Termitomyces robustus 总被引:1,自引:0,他引:1
Mondal S Chandra K Maiti D Ojha AK Das D Roy SK Ghosh K Chakarborty I Islam SS 《Carbohydrate research》2008,343(6):1062-1070
A water-soluble fucoglucan, isolated from alkali-treated edible mushroom, Termitomyces robustus, consists of L-fucose and D-glucose in a molar proportion of 1:4. Structural investigation of the polysaccharide was carried out by using total hydrolysis, methylation analysis, and periodate oxidation followed by GLC-MS, and the final structure was determined using NMR experiments (1H, 13C, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC). On the basis of the above experiments it is concluded that the following repeating unit is present in the polysaccharide: [FORMULA: SEE TEXT]. 相似文献