Search results for "FLAVONOIDS"
showing 10 items of 213 documents
Antioxidant activity and chemical composition of three Tunisian Cistus: Cistus monspeliensis Cistus villosus and Cistus libanotis
2015
The chemical composition of three rockrose Cistus species, Cistus monspeliensis, Cistus libanotis and Cistus villosus, collected in Tunisia, was studied by HPTLC, focusing on the terpenes and phenols constituents. Diterpenes of Cistus are important as the main constituents of the leaf sticky aromatic resin, known as labdanum, which are highly appreciated in perfumery. Polyphenols in the methanolic extracts of each species were identified, quantified as total and as flavonoids and tannins, and tested for antioxidant activity. Diterpenes were evident in C. libanotis and C. monspeliensis, whereas they were practically absent in C. villosus; C. libanotis had higher phenolic amount, whereas anti…
Flavonols and flavan-3-ols as modulators of xanthine oxidase and manganese superoxide dismutase activity.
2014
Experiments were performed to assess the dose-dependent effects of quercetin, kaempferol, (+) catechin, and (-) epicatechin on superoxide radical production through the modulation of manganese superoxide dismutase and xanthine oxidase activities. The experiments were carried out at flavanoid concentrations ranging from 1 µM to 100 µM. This investigation highlighted that flavonols induced opposite effects on superoxide radical production at different doses, i.e. pro-oxidant at the highest concentration (100 µM) and anti-oxidant at the lowest concentration (1 µM). Similar behaviors were observed for xanthine oxidase with flavan-3ols. The diastereoisomer (the catechin) acted as a stronger radi…
Cytotoxicity of compounds from Xylopia aethiopica towards multi-factorial drug-resistant cancer cells.
2015
Abstract Introduction Multidrug resistance (MDR) in cancer represent a major hurdle in chemotherapy. Previously, the methanol extract of the medicinal spice Xylopia aethiopica displayed considerable cytotoxicity against multidrug resistant (MDR) cancer cell lines. Methods The present study was designed to assess the cytotoxicity of compounds, 16 α -hydroxy- ent -kauran-19-oic acid ( 2 ), 3,4′,5-trihydroxy-6″,6″-dimethylpyrano[2,3-g]flavone ( 3 ), isotetrandrine ( 5 ) and trans -tiliroside ( 6 ) derived from the methanol crude extract of Xylopia aethiopica against 9 drug-sensitive and -resistant cancer cell lines. The resazurin reduction assay was used to evaluate the cytotoxicity of these c…
Effect of onion consumption by rats on hepatic drug-metabolizing enzymes
2001
Fruits and vegetables or their natural constituents which increase detoxication enzymes and/or reduce activating enzymes are considered as good candidates to prevent chemically-induced carcinogenesis. In this study, rats were fed a diet supplemented with 20% onion powder for 9 days. Several cytochrome P450 (CYP)s enzymes (CYP 1A, 2B, 2E1, 3A), which are involved in carcinogen activation, were determined by measuring their enzyme activities using specific substrates. In addition, phase II enzymes activities such as UDP-glucuronosyltransferase (UGT) and glutathione S-transferase (GST), involved in detoxication of carcinogens, were measured. Protein levels of CYPs and GST A1/A2, A3/A5, Ml, M2 …
Influence of Temperature, Solvent and pH on the Selective Extraction of Phenolic Compounds from Tiger Nuts by-Products: Triple-TOF-LC-MS-MS Character…
2019
The aim of this study was to assess the effect of temperature, solvent (hydroethanolic mixtures) and pH on the recovery of individual phenolic compounds from &ldquo
Behaviour of some compounds with lmax at 280 nm in determination of total flavonoids of grape skin extracts made from a hydroalcoholic SO2-rich solve…
2010
This paper reports the results of a study on the ambiguous behaviour of substances with lmax at 280 nm in the determination of total flavonoids in whole grape skin extracts made from a hydroalcoholic SO2-rich solvent, apparently not eluted with methanol after absorption on a C18 cartridge employed for sample pre-concentration and SO2 removal. After rejecting the hypothesis that they were irreversibly absorbed on the C18 cartridge, it seemed that they reacted with other phenolics during passage through the C18 cartridge and were totally eluted with methanol in this new combined form. This new hypothesis seems very probable and is in accord with the more recent acquisition about the synthesis…
A study of the chemical composition and biological activity of extracts from wild carrot (Daucus carota l.) seeds waste
2015
Waste (wild carrot seeds, Daucus carota L.) formed after the industrial extraction of 96% ethanol were re-extracted with 40% and 70% ethanol in order to recover of valuable substances for potential use as a safe food additives and functional food ingredients or nutraceuticals. In this study we compared chemical composition and activity of two obtained extracts (70% EtOH and 40% EtOH). The results indicated that the 70% EtOH extract has a higher total phenol and flavonoid content than 40% EtOH extract. The antioxidant activity of 70% EtOH extract was 86.88 % ± 3.018, whereas of 40% EtOH extract scavenging activity was 78.72% ± 3.276. The extracts were also active against bacteria with MIC ag…
Species-Specific Antioxidant Power and Bioactive Properties of the Extracts Obtained from Wild Mediterranean Calendula Spp. (Asteraceae)
2019
In this study we focused on four taxa of the genus Calendula (C. maritima, C. suffruticosa subsp. fulgida, C. arvensis, and the hybrid between the first two ones), collected in Mediterranean area (Sicily). Six extracts for each species were obtained using solvents with increasing polarity (hexane, ethanol 80%, acetone 70%, and water) and through extraction by supercritical fluids (SFE). It has been observed that the solvent with the highest extraction efficiency was ethanol 80% for all species. However, SFE extracts showed high antioxidant activity comparable to the ethanol 80% extract (polyphenol, DPPH, and reducing power method). These findings were confirmed by in vitro analysis (MTT ass…
Bioactive effects of citrus flavonoids and role in the prevention of atherosclerosis and cancer
2022
Citrus fruits are the main fruits of the Mediterranean diet and have been long recognized for their beneficial effects on human health. Observational studies have shown a significant association between dietary flavonoid intake and reduced risk of cardiovascular and malignant diseases. The beneficial effects of citrus fruits on human health appear to be due to their high content in vitamins, minerals and fibers. In particular, the antioxidant and anti-inflammatory activities have been indicated as some of the mechanisms through which citrus fruits may thwart the development of chronic degenerative diseases such as atherosclerosis and cancer. This review would critically examine the results …
Methods of the investigation of bee pollen and bee bread
2017
The main purpose of this publication was to evaluate which types of studies are used with the purpose of the estimation of nutritional value of bee pollen and bee bread. Bee pollen and bee bread are important bee-products that contains large amounts of nutritional and essential active biological compounds. Among different bioactive compounds with antioxidant properties which could be found in bee pollen and bread are polyphenolic substances, flavonoids, unsaturated acids and carotenoids. Bee pollen and bee bread are investigated by plenty of scientists for different quality indexes over two last decades. However, the composition of bee pollen and bee bread are not yet standardized nor defin…