Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FLAVONES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,459 records · Page 81Linked to original sources
PubMed2006

[Screening of glucosidase inhibitors from various fractions of Mulberry leaves].

OBJECTIVE: To search for glucosidase inhibitors of various fractions extracted from mulberry leaves. METHOD: The constituents of mulberry leaves water fraction were prepared by the process of boiling, condensing, precipitating, exchanging with resins and rinsing. In vitro glucosidase inhibitory activities were examined by photometric bioassay derived from rats. To investigate in vivo effect of lowering blood glucose, the mouse blood glucose level was assayed by glucose tolerance experiments. RESULT: The glucosidase inhibitory activities were found in all the constituents of alkaloids, flavones and amyloses, the alkaloid constituent being the strongest. CONCLUSION: The effect of reducing blood glucose of mulberry leaves is related to the inhibitory activities against glucosidase of different constituents.

Alkaloids↗
PubMed1991

Inhibition of rat lens aldose reductase by quercetagetin and patuletin.

In this paper the results of inhibition of the Aldose reductase (AR) activity on Wistar rat lens by Quercetagetin extracted from Tagetes erects Linn and by Patuletin extracted from Tagetes patula Linn are reported. Quercetagetin inhibited AR of the rat lens by 93.9% at 10(-4) M, 76.0% at 10(-5) M and 13.3% at 10(-6) M. Patuletin inhibited AR of the rat lens by 100% at 10(-1) M, 80% at 10(-5) M and 22.7% at 10(-6) M respectively. The results show that these two flavones are lens AR Inhibitors, but further study should be done for the possibility of clinical application.

Aldehyde Reductase↗
PubMed1999

Liquid chromatography/electrospray ionization mass spectrometric characterization of flavonol glycosides in tomato extracts and human plasma.

Flavonoids continue to attract wide attention as possible very useful agents for combating free radical pathologies, i.e. the pathological states associated with free radical overproduction. Commonly used methods for the analysis of plant flavonoids include high performance liquid chromatography (HPLC) and capillary electrophoresis (CE). On the other hand, the soft-ionization approach based on electrospray ionization (ESI-MS) permits highly selective analysis of complex matrices. In this work, we examined firstly the ESI-MS behaviour of representative aglycones and glycosides of flavonols, flavones and isoflavones with the aim of suggesting a possible relationship between structure and mass spectra. Using HPLC coupled to a diode array detector (DAD) for on-line UV spectra acquisition, and in parallel to ESI-MS for mass spectra (LC/DAD-ESI-MS), we have developed methodology to observe flavonols directly in tomato puree extract. In this way, it has been possible to detect intact flavonol glycosides in tomato extracts and to characterize a flavonol trisaccharide. For the first time, using LC/ESI-MS, it has been possible to detect intact flavonol glycosides in plasma of healthy volunteers and to provide further evidence on the absorption of flavonoid glycosides after consumption of common vegetables like tomatoes.

Calibration↗
PubMed2000

Antiproliferative effects of compounds derived from plants of Northeast Brazil.

Ten compounds derived from plants indigenous to Northeast Brazil were examined for antiproliferative effects on human cells in vitro. The effects of these phytochemicals on cell growth were determined by the MTT microtitre assay with 3-day continuous drug exposure. Three human cell lines were used: CEM leukaemia, SW1573 lung tumour and CCD922 normal skin fibroblasts. Four active compounds were found with IC(50) values less than 10 microg/mL in the two cancer cell lines. Oncocalyxones A and C, both 1,4-anthracenediones from Auxemma oncocalyx (Boraginaceae), showed cytotoxicity with mean IC(50) values of 0.8-2, 7-8 and 12-13 microg/mL against CEM, SW1573 and CCD922, respectively. One diterpene and one flavonoid, both from Egletes viscosa (Compositae), were also active. 12-Acetoxy-hawtriwaic acid lactone was cytotoxic with mean IC(50) values of 6, 10 and 10 microg/mL, respectively. 4,5-Dihydroxy-3,3,7, 8-tetramethoxy flavone (ternatin) was only growth-inhibitory with mean IC(50) values of 2, 1 and 10 microg/mL, respectively. These four most active compounds were examined further for their effects on DNA integrity and on DNA synthesis. All but ternatin caused substantial DNA damage and marked inhibition of 5-bromo-2'-deoxyuridine incorporation within 24 h. This study demonstrated the antiproliferative activity of four novel phytochemicals, three of which are DNA-reactive and inhibit DNA synthesis. Further studies are warranted to evaluate these compounds for antitumour potential.

Anthraquinones↗
PubMed1980

Regulation of human drug metabolism by dietary factors.

Several dietary factors influence the oxidative metabolism of chemicals in humans. Increasing the ratio of protein to carbohydrate or fat in the diet, feeding cabbage and brussels sprouts or feeding charcoal-broiled beef for several days stimulates human drug metabolism. The chronic ingestion of ethanol stimulates drug metabolism whereas the chronic ingestion of methylxanthine-containing foods inhibits drug metabolism. In contrast, an increase in the ratio of fat to carbohydrate in the diet of normal subjects or the fasting of obese individuals for several days has little or no effect on drug metabolism. Flavonoids in edible plants influence the metabolism of foreign chemicals by human liver in vitro. The addition of flavone, tangeretin or nobiletin to human liver microsomes activates both the hydroxylation of benzo[alpha]pyrene and the metabolism of aflatoxin B1 to mutagens. On the other hand, quercetin, kaempferol, morin and chrysin, which are also normally occurring flavonoids, inhibit the hydroxylation of benzo[alpha]pyrene by human liver microsomes.

Adult↗
PubMed1989

Synthesis of new annellated flavonoid derivatives possessing spasmolytic activity--VII.

7,8-Dihydroxyflavone reacts with ethyl 2,3-dibromopropanoate to form the new, annellated, 1,4-benzodioxanes 1 containing a flavone structural unit. The regioisomers 1a and 1b thus obtained were separated and 1a was converted to the amides 2a-2f. The constitutions of 1 and 2 were elucidated by 500 MHz 1H-NMR spectroscopy. In the spasmolysis test, 2e showed significant antagonistic effect towards the agonists acetylcholine, barium chloride, and histamine.

Chemical Phenomena↗
PubMed1997

Synthesis and bone resorption effect of alkoxy-substituted xanthones.

A topological modification of ipriflavone 1, a recent antiosteoporotic drug, is described. The flavone moiety of 1 has been replaced by a xanthone one. Among the new derivatives, the 3,6-diisopropoxyxanthone (2a) has shown significant bone resorption inhibition in in vitro and in vivo tests.

Animals↗
PubMed2006

Synthesis of new 3-(substituted phenacyl)-5-[3'-(4H-4-oxo-1-benzopyran-2-yl)-benzylidene]-2,4-thiazolidinediones and their antimicrobial activity.

Synthesis of 3-(3-nitrophenacyl)thiazolidine-2,4-dione 2g and 3-(substituted phenacyl)-5-[3'-(4H-4-oxo-1-benzopyran-2-yl)-benzylidene]-2,4-thiazolidinediones 4a-g are reported in this paper. These compounds 4a-g were prepared from 3'-flavone carboxaldehyde and 3-substituted phenacyl-2,4-thiazolidinediones using Knoevenagel reaction. The structures of all compounds were confirmed by IR, 1H-NMR, mass spectral data, and elemental analyses. The molecules 4a-g were evaluated for in-vitro antimicrobial activity against Staphylococcus aureus, Candida albicans, Candida krusei, Candida glabrata, and Candida parapsilosis. Compounds 4c and 4f showed better inhibitory activity when compared to fluconazole against Candida krusei and Candida glabrata.

Anti-Infective Agents↗
PubMed2000

Suppressive effects of flavonoids on dioxin toxicity.

Dioxin type chemicals such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) cause a variety of toxicity. Most of the toxicity of TCDD has been attributed to a mechanism by which TCDD is bound to aryl hydrocarbon receptor (AhR) and transforms the receptor. Thus, suppression of the AhR transformation by food factors can suppress the dioxin toxicity. In this study, flavonoids at various concentrations were treated to a rat cytosolic fraction containing AhR before adding 1 nM TCDD. The transformed AhR was detected by an electrophoretic mobility shift assay with a DNA oligonucleotide consensus to dioxin response element. As the results, flavones and flavonols at dietary levels act as the antagonists for AhR and suppress the transformation. The antagonistic IC50 values were in a range between 0.14 and 10 microM, which are close to the physiological levels in human. These results suggest that a plant-based diet can prevent the dioxin toxicity.

Animals↗
PubMed2004

Anthocyan does not suppress transformation of aryl hydrocarbon receptor induced by dioxin.

Dioxins cause a variety of toxic effects through transformation of a cytosolic aryl hydrocarbon receptor (AhR). We have previously demonstrated that certain natural flavones and flavonols at the dietary levels suppress AhR transformation. In this study, we investigated whether 5 anthocyanidins, 15 anthocyanins, and protocatechuic acid suppress AhR transformation in mouse hepatoma Hepa-1c1c7 cells. All the compounds tested here at 5 microM unexpectedly failed to suppress the transformation induced by 0.1 nM TCDD, indicating that anthocyan does not have a potential to prevent dioxin toxicity.

Animals↗
PubMed2004

Metabolism of eupatilin in rats using liquid chromatography/electrospray mass spectrometry.

Eupatilin (5,7-dihydroxy-3',4',6-trimethoxy flavone) is an active ingredient of an ethanol extract of Artemisia asiatica (DA-9601) that is used in the treatment of gastritis. In vitro and in vivo metabolism of eupatilin in the rats has been studied by LC-electrospray mass spectrometry. Rat liver microsomal incubation of eupatilin in the presence of NADPH and UDPGA resulted in the formation of four metabolites (M1-M4). M1, M2, M3 and M4 were tentatively identified as 3'- or 4'-O-demethyl-eupatilin glucuronide, eupatilin glucuronide, 6-O-demethyleupatilin and 3'- or 4'-O-demethyl-eupatilin, respectively. Those metabolites from in vitro study were also characterized in bile, plasma or urine samples after an intravenous administration of eupatilin to rats. In rat bile, plasma and urine samples, eupatilin glucuronide (M2) was a major metabolite, whereas M3, M4 and M4 glucuronide (M1) were the minor metabolites.

Animals↗
PubMed2004

Quantitative analysis of phytoestrogens in kudzu-root, soy and spiked serum samples by high-pressure liquid chromatography.

A sensitive and reliable HPLC method that allows simultaneous quantification of phytoestrogens extracted from kudzu-root and soy preparations, and serum samples has been developed. Kudzu-root and soy preparations were mixed with 5 microg flavone and 15 microg rutin (internal standards) and the phytoestrogens were extracted by using solid-phase (C18) extraction cartridges. Blank or spiked serum samples were extracted by using either C18 cartridges or trichloroacetic acid-methanol extraction. The extracts were analyzed by the HPLC equipped with a reverse-phase (250 x 4 mm, C18) column and UV, diode-array or MS detector. A linear gradient of acetic acid and acetonitrile provided excellent separation of glycoside and aglycone-phytoestrogens from kudzu root and soy preparations. The C18 cartridge extraction of serum yielded excellent recovery of both glycoside- and aglycone-phytoestrogens, while the trichloroacetic acid-methanol extraction yielded excellent recovery of glycoside but poor recovery of aglycone compounds. UV and MS detectors were suitable for phytoestrogen analysis in plant and serum samples, while the diode-array detector was suitable for generating the UV absorbance curve for phytoestrogens.

Chromatography, High Pressure Liquid↗
PubMed2005

Determination of the sulphoxides and sulphones of three simple sulphides in rat urine: effects of phenobarbitone, beta-naphthoflavone and methimazole.

In this investigation, the measurement and identification of the S-oxidation products of three simple sulphides-ethyl methyl sulphide (EMS), 4-chlorophenyl methyl sulphide (CPMS) and diphenyl sulphide (DPS)-in rat urine were carried out and a study of the effects of phenobarbitone (PB), beta-naphtho flavone (betaNF) and methimazole on the urinary levels of their metabolites was conducted. Male Wistar rats (n = 4) were pretreated with PB (80 mg/kg/day in saline, i.p.), betaNF (100 mg/kg/day in corn oil, i.p.), methimazole (50 mg/kg/day in saline, i.p.) or the vehicles alone (1 mL/kg) for three consecutive days. After pretreatment, EMS, CPMS or DPS (50 mg/kg in corn oil, 500 microL) was administered orally to the appropriate groups of rats. The animals were placed in metabolic cages and urine samples collected at 24 h intervals over 96 h. Chromatographic and spectroscopic techniques were used for the measurement and identification of the sulphoxides and sulphones of EMS, CPMS and DPS in rat urine. Although only a trace of ethyl methyl sulphoxide (EMSO) was present in rat urine after administration of EMS, ethyl methyl sulphone (EMSO(2)) accounted for about 16% of the administered dose in the urine of male rats given EMS. In addition, pretreatment of rats with methimazole significantly decreased the S-oxidation of EMS. 4-Chlorophenyl methyl sulphone (CPMSO(2)) was the main metabolite recovered in the urine of male rats treated with CPMS, accounting for about 10% of the dose. Pretreatment of rats with PB before administration of CPMS significantly increased the levels of CPMSO(2) excreted in the urine. Additionally, pretreatment of rats with methimazole significantly decreased the S-oxidation of CPMS in vivo. About 2.5% of diphenyl sulphoxide (DPSO) and 4% of diphenyl sulphone (DPSO(2)) were recovered in the urine of male rats given DPS. Pretreatment of rats with PB, betaNF or methimazole before administration of DPS decreased the levels of DPSO and DPSO(2) excreted in the urine, although this was not statistically significant. These results indicate that microsomal monooxygenases mediate the S-oxidation of EMS, CPMS and DPS to their corresponding sulphones via a transient sulphoxide in rats.

Animals↗
PubMed2005

Determination of zolmitriptan enantiomers in rat liver microsomes by chiral high performance liquid chromatography with fl uorescence detection.

A selective chiral high performance liquid chromatographic method was developed and validated to separate and quantify the enantiomers of a new potent selective 5-HT(1B/1D) receptor partial agonist, S-zolmitriptan, and its antipode in rat liver microsomes induced with beta-naphtho flavone. S- and R-zolmitriptan were extracted from rat hepatic microsomal incubates with chloroform/isopropanol (75:25, v/v), and were separated on a narrow-bore enantioselective normal phase Chiralpak AD-H column (250 x 0.46 mm) with hexane-isopropanol-triethylamine (72/28/0.25, v/v/v) as mobile phase and fluorescence detection with emission at 350 nm and excitation at 291 nm. The calibration curves were linear for R- and S-zolmitriptan concentration over the range 0.1-5.0 microg/mL (r = 0.9996 and 0.9999), and the limits of quantitation were 0.1 microg/mL. The metabolism and interaction of the enantiomers of zolmitriptan in treated hepatic microsomes were investigated using chiral HPLC. There was significant difference between the disposition of the S- and R-zolmitriptan when racemic zolmitriptan or single enantiomers of zolmitriptan were incubated for 5, 10 and 20 min, suggesting that the metabolism of zolmitriptan in rat liver microsomes is enantioselective. In addition, there was also a significant difference between the IC(50) of R- to S-zolmitriptan and S- to R-zolmitriptan (IC(50S/R)/IC(50R/S) = 45.2). This indicated that the disposition process favored the S-form of zolmitriptan.

Animals↗
PubMed2006

A simple HPLC method for the determination of apigenin in mouse tissues.

The flavone apigenin occurs in many leafy vegetables and fruits. It has been reported to have cancer chemopreventive efficacy in rodents. An HPLC method described previously for the determination of tricin, the dimethoxy cogener of apigenin, was modified and validated for measurement of apigenin in mouse tissues. Separation was carried out on a Hypersil-BDS C(18) column (4.6 x 250 mm) with an isocratic mobile phase of 55% methanol in 0.1 m ammonium acetate, pH 5.10, containing 0.27 mm disodium ethylenediamine tetraacetic acid. UV detection was at 336 nm, without interference from endogenous tissue compounds. The assay was linear in the range 25-400 ng/mL, 0.25-4 microg/mL and 2.5-40 microg/mL, with r(2) > 0.99 in all cases, for mouse plasma, liver and intestinal mucosa, respectively. Apigenin in mouse plasma, liver and intestinal mucosa was efficiently extracted with 0.1 m acetic acid in acetone. The assay recovery at low, medium and high concentrations was between 94.6 and 131.7% for all biomatrices, with a relative standard deviation of <10%. The lower limit of quantification for plasma was 25 ng/mL with a relative standard deviation of <15%. The method was used to measure the steady-phase apigenin levels in tissues of mice receiving apigenin in their diet.

Animals↗
PubMed1979

Identification of urinary metabolites of flavanone in the rat.

The urinary metabolites of flavanone in the rate were investigated using a gas chromatographic mass spectrometric method employing an OV-1 capillary column. Forty-three metabolites were detected and the most prominent of these were identified. The most common metabolic reactions were reduction of the keto group and hydroxylation at the 3- or 6-positions. Little hydroxylation occurred in ring B. The major metabolites were flavan-4 alpha-ol, trans-3-hydroxyflavan-4 beta-ol, 6-hydroxyflavanone and 6-hydroxyflavan-4 beta-ol. Gas chromatography analysis of underivatized flavanone metabolites, especially with stainless steel columns, results in the formation of dehydrated products including flavone, flav-3-ene and flavanone itself.

Animals↗
PubMed2006

Structure and chiroptical properties of supramolecular flower pigments.

Research over the last 30 years has shown that at physiological concentrations of ca. 5 x 10(-3) M, flower pigments composed of anthocyanins, either alone or complexed with flavone copigments, and frequently with metals, are self-assembled into non-covalent, chiral supramolecular complexes. This serves several biological functions including color stability, protection against UV radiation and provision for specific colors to attract insects for pollination. Self-association of the monomers takes place under conditions of molecular crowding by precise matching of the pi-pi stacking interactions of the aromatic chromophores and intermolecular hydrogen bonding between the attached sugars. The resulting handedness is controlled by the chiral information provided by the sugars joined glycosidically at certain positions around the periphery of the aromatic nuclei. This review gives an overview of (i) the physicochemical evidence including circular dichroism, (1)H NMR, and X-ray analysis for the structure and supramolecular chirality of these amphiphilic complexes, (ii) the role of the sugars on directing the chirality of the resulting supramolecules, (iii) the energetics of monomer association, and (iv) the possible influence of stacking chirality on insect pollination.

Anthocyanins↗