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1
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QSAR modeling for lipid peroxidation inhibition potential of flavonoids using topological and structural parameters

100%
Ray S., Sengupta C., Roy K.
Open Chemistry
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2008
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vol. 6
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issue 2
267-276
EN
In the present study, Quantitative Structure-Activity Relationship (QSAR) modeling has been carried out for lipid peroxidation (LPO)-inhibition potential of a set of 27 flavonoids, using structural and topological parameters. For the development of models, three methods were used: (1) stepwise regression, (2) factor analysis followed by multiple linear regressions (FA-MLR) and (3) partial least squares (PLS) analysis. The best equation was obtained from stepwise regression analysis (Q2 = 0.626) considering the leave-oneout prediction statistics. [...]
2
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Osmium assay in fixatives and stained rat tissues by means of acid and o,o′-dihydroxo substituted monoazo dyes and some flavonoids

100%
Rydchuk M., Mykhalyna G., Dobryanska O., Korkuna O., Vrublevska T.
Open Chemistry
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2011
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vol. 9
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issue 5
886-895
EN
New simple, rapid and accurate spectrophotometric techniques for osmium assays in fixatives and stained tissues have been elaborated using acid (Tropaeolin O, Tropaeolin OOO-I, Tropaeolin OOO-II, Orange G), o,o′-dihydroxo substituted azo dyes (Eriochrome Blue Black R, Acid Chrome Dark-Blue, Eriochrome Black T) and flavonoids (morin, quercetin, luteolin). Methods are based on sensitive osmium(IV) reactions with reagents and the formation of stable coloured compounds. Tolerance ratios of main matrix components of histological specimens during Os(IV) spectrophotometric determination with reagents has been established. Results of osmium determination in fixatives and fixed tissues, obtained by means of different reagents, appeared to be sufficiently similar, although effects of matrix components differ. The accuracy of spectrophotometric osmium assay in fixatives with azo dyes has been confirmed with voltammetric investigations. Results obtained from osmium uptake by rat gum tissues are valuable for clinical testing of dental drugs, indicating the influence of drug treatment on the gums. [...]
3
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QSAR modeling of antiradical and antioxidant activities of flavonoids using electrotopological state (E-State) atom parameters

100%
Ray S., Sengupta C., Roy K.
Open Chemistry
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2007
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vol. 5
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issue 4
1094-1113
EN
In the present paper QSAR modeling using electrotopological state atom (E-state) parameters has been attempted to determine the antiradical and the antioxidant activities of flavonoids in two model systems reported by Burda et al. (2001). The antiradical property of a methanolic solution of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and the antioxidant activity of flavonoids in a β-carotenelinoleic acid were the two model systems studied. Different statistical tools used in this communication are stepwise regression analysis, multiple linear regressions with factor analysis as the preprocessing step for variable selection (FA-MLR) and partial least squares analysis (PLS). In both the activities the best equation is obtained from stepwise regression analysis, considering, both equation statistics and predictive ability (antiradical activity: R 2 = 0.927, Q2 = 0.871 and antioxidant activity: R 2 = 0.901, Q2 = 0.841). [...]
4
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Rosehip extraction: Process optimization and antioxidant capacity of extracts

88%
Angelov G., Boyadzhieva S., Georgieva S.
Open Chemistry
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2014
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vol. 12
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issue 4
502-508
EN
This article examines the extraction of rosehip to study the recovery of a number of compounds with antioxidant properties (polyphenols, flavonoids, and β-carotene). Two varieties of rosehip, cultivated and wild are used as raw material. A detailed study of the process kinetics at different operating conditions is carried out in order to determine appropriate processing parameters, which results in extracts with higher content of target compounds and higher antioxidant capacity. Data on the concentration of active components in the different parts of the fruit (skin, seeds, and pappi) are also obtained, which gives information about their distribution within the fruit. The comparison of wild and cultivated varieties demonstrates the better quality of the cultivated one. The results are useful for production of improved and enriched rosehip extracts with higher content of antioxidant substances that have proven beneficial effects on the human health.
5
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UV-absorption studies of interaction of karanjin and karanjachromene with ds. DNA: Evaluation of binding and antioxidant activity

88%
Arshad N., Rashid N., Absar S., Abbasi M., Saleem S., Mirza B.
Open Chemistry
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2013
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vol. 11
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issue 12
2040-2047
EN
Two flavonoids, karanjin (Kj) and karanjachromene (Kc) have been investigated spectrophotometrically for their mode of interactions with double stranded (ds)-DNA at blood (7.4) and stomach (4.7) pH and at human body temperature (37°C). Benesi-Hildebrand equation was used to evaluate the binding constants, K b . Binding constants at both pH values and at body temperature showed stronger binding of both the flavonoids and formation of 1:1 flavonoid-DNA complex via intercalative mode. However, K b values for karanjin were evaluated to be comparatively greater than karanjachromene at both pH values. The highest value of binding constant (1.32×105 M−1) for karanjin at blood pH (7.4) demonstrated its comparatively stronger binding and greater effectiveness at this pH. Standard Gibbs free energy changes (ΔG) of flavonoid-DNA complexes were calculated as negative values and indicative of spontaneity of their binding. Both flavonoids showed significant DNA protection activity. [...]
6
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Antioxidant and chemical properties of Inula helenium root extracts

88%
Spiridon I., Nechita C., Niculaua M., Silion M., Armatu A., Teacă C.-A., Bodîrlău R.
Open Chemistry
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2013
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vol. 11
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issue 10
1699-1709
EN
The objective of the paper was to investigate the chemical composition of Inula helenium roots extracts and to evaluate the antioxidant potential conferred by the chemical constituents. GC/MS and HPLC/MS techniques were used to characterize two extracts separated from Inula helenium roots by extraction with chloroform and ethyl acetate, respectively. Volatile compounds have been identified by GC from their mass spectra and retention time values, while HPLC identification of phenolic compounds was realized by comparing their retention times, UV and MS spectra with those of standards or literature data. Measurements of antioxidant activity of Inula helenium root extracts showed a variation between them, which can be correlated with the flavonoid and total phenolic contents. Both Inula helenium root extracts contain phenolic acids (caffeic, chlorogenic, dicaffeoyl quinic, hydroxibenzoic), terpenes (alantolactone) and different flavonoids (epicatechin, catechin gallate, ferulic acid-4-O-glucoside, dihydroquercetin pentosyl rutinoside, kaempherol-7-O-dipentoside, quercetin-3-O-β-glucopyranoside). In addition, the study provides preliminary data on the anti-inflammatory activity of Inula helenium root extracts, this being evaluated using the fresh egg albumin as phlogistic agent, and aspirin as reference compound. Root extracts of I. helenium did not exert any significant anti-inflammatory effect on egg albumin-induced rat paw edema. [...]
7
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Monitoring of HPLC profiles of selected polyphenolic compounds in sea buckthorn (Hippophaë rhamnoides L.) plant parts during annual growth cycle and estimation of their antioxidant potential

88%
Bittová M., Krejzová E., Roblová V., Kubáň P., Kubáň V.
Open Chemistry
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2014
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vol. 12
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issue 11
1152-1161
EN
Presented work summarizes the data about polyphenolic profiles in various plant parts (leaves, shoots, berries) of sea buckthorn (Hippophaë rhamnoides L.) during the annual growth cycle. A reversed-phase high performance liquid chromatography method (RP-HPLC) coupled with diode-array detection (DAD) was optimized for determination of catechin, epicatechin, gallic acid, p-coumaric acid, caffeic acid, ferulic acid, rutin (quercetin 3-rutinoside) and quercitrin (quercetin 3-rhamnoside). The content of these polyphenolic compounds was monitored in extracts of sea buckthorn plant samples from April to October. The total antioxidant activity was determined using scavenging of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonate) cation radical (ABTS·+) and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·). The total content of polyphenols was estimated by conventional spectrophotometric method using Folin-Ciocalteu reagent. The monitoring of temporal changes of selected polyphenolic compounds by RP-HPLC showed that catechin, epicatechin and gallic acid were the most abundant analytes in annual green shoots and leaves, and their content varied significantly during the studied period.
8
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Voltammetric determination of Rutin at Screen-Printed carbon disposable electrodes

88%
Oliveira-Roberth A., Santos D., Cordeiro D., Lino F., Bara M., Gil E.
Open Chemistry
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2012
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vol. 10
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issue 5
1609-1616
EN
Rutin is a flavonoid commonly employed for many therapeutic purposes. Although the electroactive phenolic groups of rutin might be oxidized at low applied potential, the adsorption of oxidized species changes the electrode surface. As a consequence, the repeatability and reproducibility of the method decreases, which limits electroanalytical applications. This paper describes the use of disposable screen-printed electrodes as an alternative to improve the electrochemical quantification of rutin in commercial and standard samples. The electrochemical behavior was consistent to what is observed using other carbon electrodes: an adsorption-involved step and a pH-dependent oxidation process. The replacement of the electrodes between the analyses ensured rapid analysis, good intermediate precision and repeatability. The proposed method was successfully applied to rutin determination in pharmaceutical samples of capsules, with the limit of quantification being 0.30 µM. [...]
9
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Spectrophotometric studies of the reaction of quercetin with peroxynitrite at different pH

88%
Gebicka L., Stawowska K.
Open Chemistry
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2012
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vol. 10
|
issue 1
187-193
EN
Peroxynitrite (ONOOH/ONOO-) which is formed in vivo under oxidative stress is a strong oxidizing and nitrating agent. It has been reported that several flavonoids, including quercetin, inhibit the peroxynitrite-induced oxidation and/or nitration of several molecules tested; however, the mechanism of their protective action against peroxynitrite is not univocally resolved. The kinetics of the reaction of quercetin with peroxynitrite was studied by stopped-flow as well as by conventional spectrophotometry under acidic, neutral and alkaline pH. The obtained results show that the protective mechanism of quercetin against peroxynitrite toxicity cannot be explained by direct scavenging of peroxynitrite. We propose that quercetin acts via scavenging intermediate radical products of peroxynitrite decomposition (it is an excellent scavenger of ·NO2) and/or via reduction of target radicals formed in the reaction with peroxynitrite.
10
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Content available

Isolation of Flavonoids, Antioxidant and Antimicrobial Activities of Costus afer Ker Gawl. Stem Extracts

75%
Ekoro I. A., Edema M. O., Ogwuche C. E.
World News of Natural Sciences
|
2024
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vol. 53
1-16
EN
ABSTRACT Resistance to antimicrobial agents has become an increasingly important and pressing global problem. Hence, the need for substantial investment and research in the field of anti-infectives are now desperately needed if a public health crisis is to be averted. This study aims to determine the antioxidant and antimicrobial activity of Costus afer stem and isolate the flavonoids in the extracts. The method used for isolation was a combination of thin layer chromatography (TLC) and column chromatography (CC). Phytochemical screening tests were used for identification of the eluate fractions of CC to ascertain the flavonoid-rich fraction. The flavonoid content in dry stem extracts (DSE); 153 µg/g was lesser than that in fresh stem extracts (FSE) 186 µg/g. All the extracts showed activity against test organisms (Staphylococcus aureus, Escherichia coli, Pseudomonas spp.) in a concentration-dependent manner. There was an observed resistance of S. aureus against FSE at 25 mg/ml. E.coli and Pseudomonas spp were sensitive to DSE at almost all concentrations Pseudomonas spp was sensitive to almost all the control drugs except cefuroxime where it recorded a resistance. DPPH radical scavenging activity was positively correlated to the concentration of the stem extracts. FSE sample showed higher DPPH radical scavenging activity than DSE as evident in Table 3 and Fig. 2. The reducing power of the extracts followed the order of DSE < FSE < VITC. ABTS radical scavenging activity was also positively correlated to the concentrations of the stem extracts. In this analysis, FSE sample showed higher radical scavenging activity of ABTS than the DSE sample.
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