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PubMed1984

Mutagenicity of flavones, chromones and acetophenones in Salmonella typhimurium. New structure-activity relationships.

28 flavones and 11 structurally-related flavonoids, chromones, and acetophenones, were tested for mutagenicity in the Salmonella typhimurium his reversion assay. 7 flavones, all of which were hydroxy- or methoxy-substituted at position 8, were moderate to strong mutagens in strain TA100 in the presence of rat liver S9 mix. In each case, the response of strain TA98 was either not significant or was very much weaker than that observed in strain TA100. The activation by S9 is not mediated by the microsomal cytochrome P450 system, since activation was not diminished when microsomes were removed by centrifugation at 100 000 X g. The observed strain specificity and structural requirements for activity indicate a mutagenic mechanism different from that associated with previously reported mutagenic flavonols (3-hydroxy-flavones) which are most active in strain TA98. The most mutagenic flavone investigated, 5,7,8-trihydroxy-flavone (norwogonin), had a potency of 17 revertants/nmole. Simplification of the chemical structures to hydroxy-substituted chromone and acetophenone systems revealed similar strain specificity, hydroxylation requirements, and S9 dependence within these structural classes, suggesting a similar activation pathway and mutagenic mechanism. The greatest mutagenic potency was observed within the flavone series, but significant potency was retained by similarly hydroxylated chromones and acetophenones. No mutagenic activity was observed in the absence of the aryl ketone moiety.

Acetophenones↗
PubMed2002

Flavonol and flavone intakes in US health professionals.

OBJECTIVE: To determine flavonoid content of US foods, mean individual intakes, major food sources, and associations with other nutrients. SUBJECTS: US men (n = 37,886) and women (n = 78,886) who completed a semiquantitative food frequency questionnaire in 1990. DESIGN: Men and women completed a questionnaire that listed 132 items, including onions as a garnish and as a vegetable, rings, or soup. Foods known to be important sources of flavonols (quercetin, myricetin, and kaempferol) and flavones (luteolin and apigenin) were analyzed biochemically. The database contained values from the analyzed foods, previously published values from Dutch foods, and imputed values. STATISTICS: Means and standard deviations, contributions of foods to summed intake of each flavonoid, and Pearson correlation coefficients were calculated. RESULTS: Of the flavonols and flavones studied, quercetin contributed 73% in women and 76% in men. The mean flavonol and flavone intake was approximately 20 to 22 mg per day. Onions, tea, and apples contained the highest amounts of flavonols and flavones. Correlations between the intakes of flavonols and flavones and intakes of beta carotene, vitamin E, vitamin C, folic acid, and dietary fiber did not exceed 0.35. CONCLUSION: Although flavonols and flavones are subgroups of flavonoids hypothesized to be associated with reduced risk of coronary heart disease, data on flavonoid intake has been limited due to the lack of food composition data. Nutrition professionals can use these and other published data to estimate intake of flavonoids in their populations. This work should facilitate the investigation of this class of dietary antioxidants as a contributor to disease prevention.

Adult↗
PubMed2002

[Inhibitory effect of flavones from Ageratum conyzoides on the major pathogens in citrus orchard].

Inter-cropping with Ageratum conyzoides may effectively control major pathogens in citrus orchard. The research showed that flavones produced by and released from A. conyzoides could inhibit the major fungal pathogens, such as Elsimoe fawcetti Bit. Et Jenk, Collectrichum gloeosporimdes Penz, Oidium tingitaninum Carter, Capondium citri Berk et Desm in citrus orchard. 10 flavones, including one glycoside, from A. conyzoides plant were isolated and identified. Most of them could gradually degraded in soil and only 3 flavones could be accumulated and last a long time. Just these 3 flavones could obviously possess inhibitory effect on fungal pathogens in citrus orchard. The inhibitory effect of the 3 flavones was stronger, not only than those of other allelochemicals produced by and released from A. conyzoides, but also than that of Carbenzin, a commercial fungicide. Therefore, the flavones produced by and released from A. conyzoides played an important role in pathogens control in citrus orchard.

Ageratum↗
PubMed1995

Modulation of luminol-dependent chemiluminescence of murine macrophages by flavone and its synthetic derivatives.

The effect of flavone (CAS 525-82-6, 2-phenylbenzopyran-4-one, 1), flavone-8-acetic acid (CSA 87626-55-9, FAA, 2) and 10 substituted flavones on the luminol-dependent chemiluminescence of murine macrophages was studied in vitro. The synthetic derivatives were variously substituted with halo, nitro, amino, hydroxy and methoxy substituents in the 3' and 4' positions. Chemiluminescence was used in this study as an indicator for the production of reactive oxygen species by macrophages, stimulated in vitro by phorbol myristate acetate (PMA). All flavones except FAA (2) showed more than 20% inhibition at 10 mumol/l or 100 mumol/l. 3'-Amino-4'-hydroxyflavone (8) was the most potent inhibitor. The IC50s for inhibition of chemiluminescence were 4.2 +/- 1.1 mumol/l, 5.0 +/- 1.0 mumol/l and 3.3 +/- 1.4 mumol/l for resident, elicited and LPS-Poly I:C-primed macrophages, respectively. Small but statistically significant enhancements of chemiluminescence were caused by low concentrations of flavone (1), FAA (2) and 4'-methoxyflavone (6). These results suggest that modulation of the chemiluminescent capacity of macrophages depends on the nature of the substituents and the concentration of the flavones.

Animals↗
PubMed2005

Activation of mitochondrial lactate uptake by flavone induces apoptosis in human colon cancer cells.

Lactate production from glucose even in the presence of oxygen is a characteristic of cancer cell metabolism and an important feature for tumor progression. Here, we describe that an increased uptake of lactate into mitochondria of HT-29 human colon cancer cells by treatment of cells with the flavonoid flavone is associated with an increased production of mitochondrial superoxide anions and apoptotic cell death. In search of the mitochondrial transporter that could promote enhanced lactate uptake and energetic flow through the electron transport chain, we used fluorescein as a model substrate. Flavone increased fluorescein uptake at pH 7.4 into mitochondria of HT-29 cells almost tenfold while lactate inhibited uptake significantly. Uptake of fluorescein in the absence or presence of flavone was strongly increased by lowering pH from 7.4 to 6.0 and almost abolished by the protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP). The lactate-sensitive part of fluorescein transport was completely blocked by p-chloromercuribenzenesulfonic acid (pCMBS), a specific inhibitor of the monocarboxylate transporter-1 (MCT-1) that by Western blotting and immunofluorescence was identified in mitochondria of HT-29 cells. Finally, lactate increased and pCMBS inhibited the flavone-induced generation of mitochondrial O2-* radicals and in turn blunted the apoptotic response. In conclusion, our studies provide evidence that flavone reverts the metabolic phenotype of transformed colonocytes towards a phenotype characteristic for normal cells. Transformed colonocytes, however, seem especially vulnerable to O2-*, produced in mitochondria as a consequence of these metabolic alterations, and respond with the induction of apoptosis.

Apoptosis↗
PubMed2007

Effects of Kaempferia parviflora extracts and their flavone constituents on P-glycoprotein function.

The purpose of this study was to examine the effects of extracts and flavone derivatives from the rhizome of Kaempferia parviflora on P-glycoprotein (P-gp)-mediated transport in LLC-GA5-COL150, a transfectant cell line of a porcine kidney epithelial cell line LLC-PK1 with human MDR1 cDNA. Ethanol extract obtained from Kaempferia parviflora rhizome significantly increased the accumulation of rhodamine 123 and daunorubicin, P-gp substrates, in LLC-GA5-COL150 cells, but not in LLC-PK1 cells. The aqueous extract also increased the accumulation in LLC-GA5-COL150 cells with lower potency than the ethanol extract. The effects of flavone derivatives isolated from the rhizome of Kaempferia parviflora on P-gp function were examined. Among six flavones tested, 3,5,7,3',4'-pentamethoxyflavone most potently increased the accumulation of rhodamine 123 and daunorubicin in LLC-GA5-COL150 cells in a concentration-dependent manner. In addition, 5,7-dimethoxyflavone to lesser degree increased rhodamine 123 accumulation in LLC-GA5-COL150 cells. In contrast, the other four flavone derivatives had no significant effect on the accumulation of rhodamine 123 in LLC-GA5-COL150 cells in a concentration range tested. These results indicate that extracts and flavone derivatives from the rhizome of Kaempferia parviflora can inhibit P-gp function, which may be useful for overcoming P-gp-mediated multidrug resistance and improving the oral bioavailability of anticancer agents.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Flavone initiates a hierarchical activation of the caspase-cascade in colon cancer cells.

There is emerging evidence that dietary factors can prevent cancer by affecting the process of carcinogenesis. Flavonoids present in vegetarian food possess antioxidant activities, have scavenging effects on activated carcinogens and mutagens, affect cell cycle progression and alter gene and protein expression. We report here that flavone, the core structure of the flavone subgroup, potently inhibits proliferation and induces apoptosis in HCT-116 colon cancer cells. Flavone induces the activation of caspases 2, 3, 8, 9 and 10 and a decrease of mitochondrial anti-apoptotic Bcl(2) protein expression. Further analysis revealed that caspase 10 activation is mediated via caspase 1. Additionally, treatment with flavone results in release of the mitochondrial apoptosis-inducing factor (AIF), the key trigger of caspase-independent apoptosis, into the cytosol. In summary, our data show that flavone induces apoptosis in a caspase-dependent and -independent manner.

Amino Acid Chloromethyl Ketones↗
PubMed2005

Determination of flavone C-glucosides in antioxidant of bamboo leaves (AOB) fortified foods by reversed-phase high-performance liquid chromatography with ultraviolet diode array detection.

Reversed-phase high-performance liquid chromatography (RP-HPLC) with ultraviolet diode array detection (UV-DAD) was used for the simultaneous determination of four flavone C-glucosides, i.e. orientin, homoorientin, vitexin and isovitexin in several food systems fortified by the antioxidant of bamboo leaves (AOB), such as high temperature sterilized milk, sunflower seed oil and extruded rice cake for the first time. The method included extraction of flavone C-glucosides from AOB-fortified foods by methanol aqueous solution, deproteinating with saturated lead acetate solution and potassium oxalate, defatting with n-hexane and clean-up by solid-phase extraction (SPE) with Phenomenex C18 cartridges. Analytes were separated with Luna C18 5 microm 250mm x 4.6mm column using acetonitrile and 1% (v/v) acetic acid (pH 3.0) as mobile phase. Good results were obtained with respect to repeatability (relative standard deviation (RSD)< 2.2%) and recovery (81.4-91.8%) which fulfilled the requirements defined by European Union (EU) legislation. The total amounts of four flavone C-glucosides were 12.56 microg/100 mL, 881.08 microg/100 mL and 1420.83 microg/100 g dry weight in AOB-fortified sterilized milk, sunflower seed oil and extruded rice cake, respectively. The method was successfully applied to the analysis of flavone C-glucosides in AOB-fortified samples. The optimized procedure could also be referenced for the separation of flavone C-glucosides in other fortified foodstuffs.

Antioxidants↗
PubMed2005

Retention behavior of silica-bonded and novel polymeric reversed-phase sorbents in studies on flavones as chemotaxonomic markers of Scutellaria L. genus.

In this study, the effectiveness of both classical and novel polymeric sorbents used in solid-phase extraction (SPE) for isolation of pharmacologically active flavones (baicalin, luteolin, apigenin, wogonin and chrysin) from aerial parts of 13 species of Scutellaria L. (Skullcap) genus was assessed. The highest recoveries of hydrophilic (baicalin, luteolin) flavones for Oasis HLB were obtained, whereas for medium hydrophobic (apigenin) and hydrophobic (wogonin, chrysin) flavones better quantitative results for BakerBond phenyl cartridges were stated. Eluates were analysed using reversed-phase high-performance liquid chromatography with diode array detection (RP-HPLC-DAD). For the five target compounds the determined concentrations ranged from approximately 4 to approximately 15,500 microg/g dry wt. Very good linearities (r(2)>0.9995) of calibration curves were achieved for each flavone. The accuracy was below 5% for most compounds examined. This is the first method reported that enabled simultaneous qualification and quantitation of five flavones (being chemotaxonomic markers) in 13 species of Scutellaria L. genus.

Apigenin↗
PubMed2004

Direct liquid chromatography-mass spectrometry method for the detection of glutathione S-transferase isozymes and investigation of their expression in response to dietary flavone.

The cytosolic GSTs were measured directly in tissue homogenates using HPLC interfaced via ESI to a mass spectrometer (LC/MS). Total ion chromatograms were generated and filtered for ion currents corresponding to m/z ratio characteristic of individual GST isozymes. Direct LC/MS has a high degree of precision (8%) and low instrument detection limits (50-100 ng) and offers the advantage of monitoring GST expression at the protein level. In this study we describe the sub-chronic effect of feeding flavone (2500 mg/kg diet) on the expression of mGSTA3, mGSTP1, mGSTM1, and mGSTM2 in male and female mice. Additionally, we tentatively identify mGSTO and its up-regulation by flavone; a result that will facilitate the study of this novel enzyme. Flavone induced mGSTM1 and mGSTP1 in a gender and isozyme specific manner yet had no appreciable effect on the expression of mGSTA3. Male animals (day 5) displayed a 8-fold increase in mGSTM1 and a 2.6-fold increase in mGSTP1 whereas female animals displayed a 5- and 3-fold increase in mGSTM1 and mGSTP1, respectively. The mGSTM2 was detected only in flavone-fed animals, indicating an up-regulation of this isozyme by flavone. Results obtained using direct LC/MS compare favorably to the specific activity of individual isozymes (P = 0.19), and are comparable to GST levels determined using affinity chromatography followed by LC/MS (P = 0.79).

Animals↗
PubMed2005

Radioiodinated flavones for in vivo imaging of beta-amyloid plaques in the brain.

In vivo imaging of beta-amyloid (A beta) peptide aggregates in the brain may lead to early detection of Alzheimer's disease (AD) and monitoring of the progression and effectiveness of AD treatment. The purpose of this study was to develop novel amyloid imaging agents based on flavone as a core structure. Radioiodinated flavone derivatives were designed and synthesized. The binding affinities of flavone derivatives for A beta aggregates varied from 13 to 77 nM. When in vitro plaque labeling was carried out using post-mortem AD brain sections, all flavones intensely stained not only amyloid plaques but also cerebrovascular amyloids. In biodistribution studies using normal mice, they displayed high brain uptakes ranging from 3.2 to 4.1% ID/g at 2 min postinjection. The radioactivity washed out from the brain rapidly (0.5-1.9% ID/g at 30 min), which is highly desirable for amyloid imaging agents. The results in the study suggest that these classes of radioiodinated flavones may be useful candidates as potential imaging agents for amyloid plaques.

Aged↗
PubMed2004

Effects of dihydrogenation of flavones and number of hydroxy groups in the molecules on ocular blood flow in rabbits and retinal function recovery in rats.

PURPOSE: It has been found that the number of hydroxy groups in the molecule of flavones and flavanones affect the ocular blood flow significantly. However, the effects of dihydrogenation of flavones into flavanones on ocular blood flow and retinal function recovery have not been studied and required investigation. METHODS: The colored microsphere technique and electroretinography method were used for the study of ocular blood flow and retinal function, respectively. RESULTS: Maximum effects on ocular blood flow were obtained when there were 3 hydroxy groups in the molecule of flavones and flavanones. Dihydrogenation of flavones to flavanones increased the ocular blood flow further. The same is true for retinal function recovery after ischemic insult. CONCLUSION: These results indicate that hydrogenation is an excellent way to convert natural flavones into more potent compounds of flavanones.

Animals↗
PubMed1995

Enhancement of rat hepatic and gastrointestinal glutathione and glutathione S-transferases by alpha-angelicalactone and flavone.

The naturally occurring anticarcinogens flavone and alpha-angelicalactone incorporated separately and simultaneously in the diet at 0.5, 0.1, 0.05 and 0.01% w/w, were studied with respect to their effects on oesophageal, gastric, intestinal, colonic and hepatic (i) glutathione S-transferase (GST) enzyme activity, (ii) GST isozyme levels and (iii) glutathione (GSH) content in male Wistar rats. GST enzyme activity was significantly increased in the three treatment groups at one or more sites. The most substantial inductions were seen in oesophagus and stomach by 0.5% alpha-angelicalactone (1.9- and 2.3-fold respectively); and in small intestine, colon and liver by 0.5% combination diet (2.5-, 1.4- and 4.0-fold respectively). The inducing capacities declined with decreasing anticarcinogen concentrations. GST enzyme activity was induced in liver and to a lesser extent in small intestine and stomach. In general, in combination groups similar effects were seen as after treatment with alpha-angelicalactone or flavone separately. However, colonic GST enzyme activity was increased in the 0.5% combination group (1.4-fold), whereas in the corresponding flavone or alpha-angelicalactone groups no induction was observed. Concomitant changes in GST isozyme levels occurred. The involvement was the highest for GST-alpha (75%), followed by GST-mu (58%) and GST-pi (33%). Increased GSH levels were obtained in stomach and liver in all three treatment groups at various concentrations. These data demonstrate that dietary administration of flavone or alpha-angelicalactone, even at relatively low concentrations, may exert chemopreventive effects in stomach, small intestine, liver and to a lesser extent in oesophagus by enhancing the GST detoxification system, mainly by induction of GST-alpha and GST-mu isozymes. In addition, simultaneous administration of flavone and alpha-angelicalactone may result in anticarcinogenic effects in the colon by the same principle.

4-Butyrolactone↗
PubMed2004

Induction of G1 cell cycle arrest in human umbilical vein endothelial cells by flavone's inhibition of the extracellular signal regulated kinase cascade.

Dietary flavonoids have demonstrated anti-carcinogenic activity in several animal models, but their mechanisms of action have not yet been clearly established. Here, we show that flavone, a parent compound of flavonoids, inhibits the proliferation, migration, and capillary tube formation of human umbilical vein endothelial cells (HUVECs). Flow cytometric analysis showed that flavone arrests the cell cycle progression at G(1) phase in HUVECs. We observed the down-regulation of the hyperphosphorylated form of retinoblastoma gene product and cyclin-dependent kinases 2 and 4 in flavone-treated cells, but it had no affect on the expression of p53 and cyclin-dependent kinase inhibitors p21(CIP/Waf1) and p27(Kip). Flavone almost completely inhibited the activation of extracellular signal regulated kinase 1. The present results suggest that the flavone moiety of flavonoids is required for anti-proliferative activity of flavonoids and that anti-carcinogenic action of flavonoids in vivo was mediated, at least in part, by inhibiting angiogenesis.

CDC2-CDC28 Kinases↗
PubMed2000

Antinociceptive pattern of flavone and its mechanism as tested by formalin assay.

Flavone, dextrose and long swim stress exhibited antinociception. Degree of antinociception was greater with long swim stress as compared to flavone or dextrose. Combination of these treatments resulted in potentiation of antinociception. Naloxone (opioid antagonist; 5 mg/kg i.p.) antagonised flavone or long stress induced antinociception showing opioid medicated mechanism, however, failed to reverse the potentiated antinociceptive component recorded in long stressed animals which received flavone and dextrose. Antinociceptive activity of flavone, dextrose and long swim stress which was documented by acetic acid assay has been confirmed in the present study. Role for opioid system in this action has been demonstrated. Therefore, formalin test can also be considered as an useful assay procedure for testing flavonoids. However, like acetic acid assay this assay procedure also has the limitation that it is unable to detect minor changes in the degree of antinociception produced by physiological interventions such as long swim and dextrose.

Analgesics↗
PubMed2004

Evaluation of the first-pass glucuronidation of selected flavones in gut by Caco-2 monolayer model.

PURPOSE: Four flavones, namely Apigenin, Baicalein, Chrysin and Luteolin, were selected for study and comparison of their absorption and metabolism in gut using the in vitro Caco-2 monolayer model. METHODS: Transport of the four flavones in the Caco-2 monolayer model was studied in both Apical-to-Basolateral and Basolateral-to-Apical directions. RESULTS: All of the selected flavones were able to pass through the Caco-2 cell monolayer with no significant efflux. The permeability coefficients of the four compounds were all greater than 10(-6) cm/sec and those of Apigenin and Baicalein were even greater than 10(-5) cm/sec. Glucuronides of the tested flavones were all formed in the Caco-2 cell monolayer model and a structure-activity relationship has been proposed for this glucuronidation. In addition, Apical-to-Basolateral transport studies were performed in Caco-2 models pre-treated with Chrysin, an UGT inducer. Quantities of the corresponding glucuronides formed were all significantly higher in Chrysin-treated groups than the controls. CONCLUSIONS: It demonstrated that all selected flavones were substrates of the UGT isoforms that are inducible by Chrysin.

Biological Transport↗
PubMed2006

[Simultaneous determination of total flavone and total saponin in Gynostemma pentaphyllum by signal multiplier spectrophotometry].

Important chemical constituents analysis for the total flavone and total saponin in Gynostemma pentaphyllum is described. The colour reactions of flavones and saponines with vanillin-perchloric acid in acetic acid produced the good absorptions at 451 and 547 nm, but the absorption peaks too overlapped to be determined simultaneously. A new method for the total flavone and the total saponin in Gynostemma pentaphyllum to be determined by signal multiplier spectrophotometry simultaneously without any preliminary separation was proposed. For quantitative analysis, the rutinum as a standard of the total flavone and the ginsenoside Rb1 as standard of the total saponin were applied. The experiment results showed that the regression equations of concentration and deltaA were obtained: deltaAflavone = 0.0133+4.417 0Cflavone, relation coefficient rflavone = 0.9994, and the total flavone concentrations were in 0-0. 16 microg x mI(-1) with deltaA obeying linear relation; deltaAsaporin = 2.775 5Csaponin -0.8881 x 10(-2), relation coefficient rsaponin = 0.9991, and the total saponin concentrations were in 0-0.30 microg x mL(-1) with deltaA obeying linear relation respectively. The recovery ratio was 104.0%-113.0% and 86.8%-94.6% respectively. The RSDflavone was less than 0.58% (n = 9) and RSDsaponin was less than 0. 35% (n=9) respectively. The proposed method is simple, rapid accurate and feasible.

Feasibility Studies↗
PubMed2004

3-OH flavone inhibition of epidermal growth factor-induced proliferaton through blocking prostaglandin E2 production.

Epidermal growth factor (EGF) has been shown to induce proliferation in cells, however, the role of prostaglandin E(2) (PGE(2)) plays in EGF-induced proliferation in still unclear. EGF and PGE(2) showed proliferation responses in epidermoid carcinoma cell A431 by MTT and [(3)H] thymidine incorporation assay. Activation of the EGF receptor and extracellular signal-regulated protein kinases (ERK1/2), but not p38 and JNK, appeared 10 min after EGF treatment, whereas total amounts of ERK1/2, p38 and JNK remained unchanged in A431 cells, accompanied by induction of COX-2 and PGE(2) production. PD98059, a specific ERK1/2 inhibitor, inhibited EGF-induced proliferation with concomitant decreases in ERK1/2 phosphorylation and COX-2/PGE(2) induction. Non-steroid anti-inflammatory drugs (NSAIDs) such as aspirin and diclofenac, a COX activity inhibitor, inhibited EGF-induced proliferation by blocking PGE(2) production. The addition of PGE(2) reversed the inhibitory effects of PD98059, aspirin, and diclofenac on EGF-induced proliferation. This suggests that COX-2/PGE(2) activation involves in EGF-induced proliferation and locates at the downstream of ERK1/2 activation. Furthermore, the natural product, 3-OH flavone, showed the most-potent inhibitory activity on EGF-induced proliferation among 9 structurally-related compounds, and suppression of EGF receptor phosphorylation, ERK1/2 phosphorylation, and COX-2/PGE(2) production by 3-OH flavone was identified. PGE(2) addition attenuates the inhibitory activity of 3-OH flavone on EGF-induced proliferation by MTT assay and colony formation by soft agar assay. Additionally, 3-OH flavone also showed more-specific inhibition on EGF- than on fetal bovine serum (FBS)-induced proliferation in A431 cells. Results of our present study provide evidence to demonstrate that PGE(2) is an important downstream molecule in EGF-induced proliferation, and 3-OH flavone, which inhibits PGE(2) production by blocking MAPK cascade, might reserve potential for development as an anti-cancer drug.

Anti-Inflammatory Agents, Non-Steroidal↗