74 resultados para phenolic compound


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Phenolic contents of extracts of Syzygium cumini leaves, collected monthly over a one-year period, were quantitatively determined by the modified Folin-Ciocalteau method. Extracts and tannin-free fractions were assayed by their potential to inhibit mouse paw edema induced by C48/80. HPLC showed high molecular weight phenolic species and flavonoids in the active extracts and fractions. The highest total phenolic content corresponded to the most potent degree of inhibition and the flavonoids were supposed to be the main species responsible for the activity, given that the flavonoid-enriched ethyl-acetate fraction maintained its effect down to a dose of 0.01 mg/kg in a dose-response manner.

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This research work aimed at determining the UVA effectiveness (UVA I/UV ratio), by diffuse transmittance analysis, of sunscreens developed with a bioactive substance, the rutin, associating or not with organic UVB-UVA filters incorporated at a phosphate-base O/W emulsion. Sunscreens provided conflicting and unpredictable results concerning the anti-UVA protection, specially, at the UVA I region. Possible interactions among the organic UV filters and the polyphenolic bioactive substance may have accounted with improvement or reduction of UV protection by a complex and not yet elucidated mechanism, probably regarding wavelength delocalization to superior or inferior values, by resonant molecule stabilization or destabilization.

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Sidastrum paniculatum (L.) Fryxell belongs to the family Malvaceae and is popularly known as "malva roxa" or "malvavisco". The phytochemical study of the hexane, CHCl3 and EtOAc phases from the crude ethanol extract of S. paniculatum led to the isolation of six compounds: a mixture of β-sitosterol and stigmasterol, 4-methoxy-3-hydroxybenzoic acid, 4-methoxy-3-hydroxybenzaldehyde, N-trans-feruloyltyramine and kaempferol-3-O-β-D-(6''-E-p -coumaroyl) glucoside. The structural identification of the compounds was made on the basis of spectroscopic methods such as IR, ¹H and 13C NMR with the aid of including two-dimensional techniques, besides comparison with literature data. The β-sitosterol and stigmasterol mixture showed a significant anti-inflammatory activity.

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This paper describes the antioxidant effects of thirteen phenolic compounds isolated from plants of the genus Lychnophora. Two assays were performed to evaluate these effects: a cellular test that measured the luminol-enhanced chemiluminescence produced by neutrophils stimulated with opsonized zymosan and a cell-free test involving horseradish peroxidase-H2O2-luminol. In both assays, the antioxidant activity of the phenolic compounds was dependent on their concentration and chemical structure. Our results suggest that the ability of phenolic compounds from Lychnophora species to scavenge and inhibit the generation of ROS may be a mechanism underlying the anti-inflammatory activity of extracts from Lychnophora spp.

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The electrochemistry of 2,2-dimethyl-(3H)-3-(N-3'-nitrophenylamino)naphtho[1,2- b]furan-4,5-dione ([Q]-PhNO2), on mercury was investigated. The first peak is consistent with a quasi-reversible one-electron reduction of the ortho-quinone, forming [Q•-]-PhNO2, while the second one, bielectronic, corresponds to the simultaneous reduction of the latter radical to a dianion and the nitro group to a nitro radical anion. The second order rate constant, k disp, for the decay of [Q•-]-PhNO2 is 15.188 x 10³ ± 827 mol"1 L s"1 and the t1/2 equals 0.06 s. E¹7Ic values for [Q]-PhNO2 and its precursor, nor-β-lapachone, are similar. The ease of semiquinone generation and its stability are parameters statistically relevant in the correlation biochemical/theoretical aspects.

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From the aerial parts of Sidastrum micranthum (A. St.-Hil.) Fryxell (Malvaceae) were isolated m-methoxy-p-hydroxy-benzaldehyde, o-hydroxy-benzoic acid, acacetin, quercetin, 7,4′-Di-O-methylisoscutellarein, genkwanin and tiliroside. These compounds were identified by data analyses of spectroscopic methods. Although acacetin and 7,4′-Di-O-methylisoscutellarein did not display relevant antibacterial activity (MIC = 256 µg/mL), they modulated the activity of antibiotics, i.e. in combination with antibiotics at 64 µg/mL (¼ MIC), a two-fold reduction in the MIC was observed for norfloxacin and ethidium bromide; regarding tetracycline and erythromycin a two-fold reduction in the MIC was observed only with 7,4′-Di-O-methylisoscutellarein.

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Inclusion compound of rhodium(II) citrate with β-cyclodextrin in a 1:1 molar ratio was prepared using freeze-drying method. X-ray diffactometry, thermal analysis (TG/DTG/DSC), infrared and ¹H-NMR with ¹H spin lattice relaxation (¹H T1) measurements and 13C techniques were used to characterize the system prepared. The results indicated the formation of inclusion or association compounds between rhodium(II) citrate and β-cyclodextrin.

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This study describes the chemical investigation of the ethyl acetate fraction obtained from the hydroethanolic extract of the xylopodium of Cochlospermum regium (Mart. & Schr.) Pilger, which has been associated with antimicrobial activity. Phytochemical investigation produced seven phenol derivatives: ellagic acid, gallic acid, dihydrokaempferol, dihydrokaempferol-3-O-β-glucopyranoside, dihydrokaempferol-3-O-β-(6"-galloyl)-glucopyranoside, pinoresinol, and excelsin. It also contained two triacylbenzenes, known as cochlospermines A and B. The hydroethanolic extract and its fractions exhibited antimicrobial activity (0.1 mg/mL) against Staphylococcus aureus and Pseudomonas aeruginosa. Gallic acid showed activity against S. aureus. Dihydrokaempferol-3-O-β-(6"-galloyl)-glucopyranoside is reported here for the first time in the literature.

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This study describes the isolation and structural determination of two amides, isolated for the first time: N,4-dihydroxy-N-(2'-hydroxyethyl)-benzamide (0.019%) and N,4-dihydroxy-N-(2'-hydroxyethyl)-benzeneacetamide (0.023%). These amides, produced by the red macroalgae Bostrychia radicans, had their structures assigned by NMR spectral data and MS analyses. In addition, this chemical study led to the isolation of cholesterol, heptadecane, squalene, trans-phytol, neophytadiene, tetradecanoic and hexadecanoic acids, methyl hexadecanoate and methyl 9-octadecenoate, 4-(methoxymethyl)-phenol, 4-hydroxybenzaldehyde, methyl 4-hydroxybenzeneacetate, methyl 2-hydroxy-3-(4-hydroxyphenyl)-propanoate, hydroquinone, methyl 4-hydroxymandelate, methyl 4-hydroxybenzoate, 4-hydroxybenzeneacetic acid and (4-hydroxyphenyl)-oxo-acetaldehyde. This is the first report concerning these compounds in B. radicans, contributing by illustrating the chemical diversity within the Rhodomelaceae family.

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The B3LYP/6-31G (d) density functional theory (DFT) method was used to study molecular geometry, electronic structure, infrared spectrum (IR) and thermodynamic properties. Heat of formation (HOF) and calculated density were estimated to evaluate detonation properties using Kamlet-Jacobs equations. Thermal stability of 3,6,7,8-tetranitro-3,6,7,8-tetraaza-tricyclo [3.1.1.1(2,4)]octane (TTTO) was investigated by calculating bond dissociation energy (BDE) at the unrestricted B3LYP/6-31G(d) level. Results showed the N-NO2 bond is a trigger bond during the thermolysis initiation process. The crystal structure obtained by molecular mechanics (MM) methods belongs to P2(1)/C space group, with cell parameters a = 8.239 Å, b = 8.079 Å, c = 16.860 Å, Z = 4 and r = 1.922 g cm-3. Both detonation velocity of 9.79 km s-1 and detonation pressure of 44.22 GPa performed similarly to CL-20. According to the quantitative standards of energetics and stability, TTTO essentially satisfies this requirement as a high energy density compound (HEDC).

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The antioxidant activities and polyphenolic levels of "assa peixe," "cambara," and "morrão de candeia" Brazilian honeys were investigated. Phenolic extracts of 11 honeys were evaluated spectrophotometrically to determine their total phenolic and flavonoid contents, and their antioxidant activities were measured using DPPH, ABTS, and FRAP assays. High-performance liquid chromatography coupled with diode array detection was applied to determine the phenolic composition of the honey extracts. The presence of fourteen phenolic compounds was established (eleven phenolic acids and three flavonoids), as well as HMF and abscisic acid. Principal component analysis was applied to classify the honey samples according to their floral origins.

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Among other applications, Ipomoea pes-caprae is popularly used to treat jellyfish stings, supporting the development of a product for dermatological use. Hydroethanolic spray-dried extract was chosen for the further development of phytomedicines, and a stability-indicative HPLC-UV method was developed and validated for the determination of isoquercitrin and isochlorogenic acids A, B and C. The method was developed using a C18 column (250 x 4.6 mm, 5 µm) with an acetonitrile:water mobile phase at pH 3.0 in a gradient run. The four constituents and other unidentified components of the extract were appropriately resolved without interference of degradation products after stress tests (acid, alkali, neutral, oxidant, photolysis). The method showed linearity in the isoquercitrin concentration range from 5.0-50.0 µg mL-1, with adequate precision (RSD% < 2.5% for the intra- and inter-day studies), accuracy (recovery of 100.0 ± 2.0%), and robustness. Both the herbal drug and spray-dried extract of I. pes-caprae were subjected to stability studies in accelerated and long-term conditions over four months. The samples maintained their characteristics and marker contents (< 10% of variation).

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A novel heteronuclear 3d-4f compound having formula NdCu3L3·13H2O (where H3L = Schiff base derived from 5-bromosalicylaldehyde and glycylglycine and L³ = C11H8 N2O4Br) was obtained. It was characterized by elemental and thermal analyses and magnetic measurements. The Cu(II)-Nd(III) compound is stable up to 323 K. During dehydration process the water molecules are lost in two stages. The magnetic susceptibility data for this complex change with temperature according to the Curie-Weiss law with theta = -35 K. The magnetic moment values decrease from 5.00µB at 303 K to 4.38µB at 76 K.

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Five flavanones and three chalcones were isolated from Campomanesia adamantium Berg. (Myrtaceae) leaves. The contents of these compounds were determined by HPLC. The phenolic contents were also determined. The monitoring of the antioxidant activity was carried out by inhibition of peroxidation using the linoleic acid system and radical-scavenging (DPPH). The plants were collected from 4 distinct cities of the Mato Grosso do Sul State, Brazil. The different samples exhibited a range of 4.67-232.35 mg/g chalcones and 15.62-50.71 mg/g flavanones and phenolic contents of the 7.24-21.19 mg/g gallic acid. All extracts showed high antioxidant activity with a wide range of the radical-scavenging (DPPH) from 52.0 to 92.2 % and inhibition oxidation of linoleic acid from 14.6 to 94.2%.

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ABSTRACTThe objective of this study was to test the hypothesis that biochar, applied with cattle manure, promotes better development of seedlings of Magonia pubescens St. Hil. The experiment was conducted at the State University of Mato Grosso, Nova Xavantina, Brazil, in 2011. We used a completely randomized design, with twelve treatments and three replications. The substrates formed by the higher levels of cattle manure plus biochar (30%) provided better results of height, diameter and aerial biomass. However, the Dickson Quality Index has not confirmed the quality of seedlings in these treatments. We also observed that the doses of biochar (20 and 30%) when added separately to the Latosol, are not efficient for the growth improvement of the seedlings. Based on the present results, we validate the hypothesis that substrates formed with a mixture of cattle manure and biochar are effective to improve the production of seedlings of M. pubescens.