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PubMedDate not supplied

Modulating luminol-dependent chemiluminescence of neutrophils by flavones.

The effect of 14 flavones on luminol-dependent chemiluminescence of neutrophils was studied in vitro. Chemiluminescence was used in this study as an indicator for the production of a reactive oxygen species by neutrophils, stimulated by phorbol myristate acetate. While flavone-8-acetic acid, and most of the compounds tested, inhibited chemiluminescence, flavone and its 5-hydroxy-7-methoxy derivatives enhanced it by up to 150%. The most active inhibitors of photon emission were the glycosides. These results indicate that lipophilicity and some structural determinants modulate the chemiluminescent capacity of neutrophils.

Animals↗
PubMed1999

Flavone antagonists bind competitively with 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) to the aryl hydrocarbon receptor but inhibit nuclear uptake and transformation.

Previous analyses suggested that potent aryl hydrocarbon receptor (AhR) antagonists were planar, with a lateral electron-rich center. To further define structural requirements and mechanism for antagonism, ten additional flavone derivatives were synthesized. Based on their ability to 1) compete with 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) for binding to the AhR; 2) inhibit TCDD-elicited binding of AhR to dioxin-responsive elements (DRE) in vitro; and 3) inhibit TCDD-induced transcription of DRE-dependent luciferase in stably transfected hepatoma cells, the most potent flavones contained a 3'-methoxy group and a 4'-substituent having one or more terminal atoms of high electron density (-N3, -NO2, or -NCS). Furthermore, these had low agonist activity as assessed by their inability to elicit AhR. DRE binding or to induce luciferase. Compounds containing bulkier 3' or 4'-substituents, or a 3'-OH group were less potent antagonists, and some were partial agonists. In rat liver cytosol, 3'-methoxy-4'-azido- and 3'-methoxy-4'-nitroflavones bound competitively (with TCDD) to the AhR, indicating that they bind to the TCDD-binding site. When hepatoma cells were exposed to these flavones, AhR complexes were primarily immunoprecipitable from the cytosol and contained 90 kDa heat shock protein. In contrast, AhR in TCDD-treated cells was primarily immunoprecipitated from nuclear extracts and was associated with Arnt but not 90 kDa heat shock protein. Immunocytofluorescence analysis in intact cells further indicated that the potent antagonist inhibited nuclear uptake of AhR and blocked TCDD-dependent down-regulation of AhR. Together, these data indicate that the most potent antagonists bind the AhR with high affinity but cannot initiate receptor transformation and nuclear localization.

Animals↗
PubMed2001

A new flavone derivative from Ehretia ovalifolia leaves.

From the methylene chloride extract of Ehretia ovalifolia leaves, a new flavone derivative named ovalifolin [3-(3-methyl-1-butenyl)-6-methoxy-5,7,4'-trihydroxy flavone] has been isolated and identified together with the known flavone aglycones apigenin, luteolin and the highly methoxylated flavanol araneosol. The structures of these metabolites have been established on the basis of chemical, chromatographic and spectral methods.

Chromatography, Thin Layer↗
PubMed2001

The biological basis of epistasis between quantitative trait loci for flavone and 3-deoxyanthocyanin synthesis in maize (Zea mays L.).

A major weakness in our understanding of the genetic basis of complex traits has been that of defining the extent and biological basis of epistasis. Our research group has been studying the genetic control of the accumulation of maysin, a C-glycosyl flavone, in maize, Zea mays (L.), silks. Previously, we demonstrated the importance of the p1 locus as a QTL for maysin synthesis. The p1 locus often exhibits significant epistatic interactions with other loci. We developed a mapping population, (W23al x GT119)F2, specifically designed to test whether genes in an intersecting pathway might be detected as QTLs for maysin synthesis and result in epistatic interaction effects. The a1 gene is not required for the synthesis of flavones but is required for the synthesis of 3-deoxyanthocyanins, an intersecting pathway, in maize silks. The p1 locus (P < 0.0001) was a QTL for both flavones and 3-deoxyanthocyanins. The a1 locus was also highly significant (P < 0.0001) for both traits, as was the p1 x a1 epistatic interaction (P < 0.0001). Our results demonstrate that altering the flux of biochemical intermediates between pathways may be the biological basis of major QTL effects and epistatic interactions.

Alleles↗
PubMed2002

Anti-nociceptive effect of synthesized di-hydroxy flavones: possible mechanism.

Renewed interest on the research on the flavonoids is gaining more importance. Earlier literature on flavonoids indicated a significant anti-nociceptive action for flavones and mono-substituted flavones. However, they exhibited a ceiling effect. The present study was undertaken by new synthesizing six disubstituted flavones (DHFs) since poly substituted ones are expected to produce more potent effect. Their anti-nociceptive effect and the role of opioid involvement were studied using acetic acid induced abdominal constriction assay. All the six DHFs administered in elicited a dose related inhibition of abdominal constrictions indicating the presence of the anti-nociceptive response. However, these substances also showed a similar ceiling effect. Like other flavonoid substances, they also utilized opioid pathways. It is suggested that these newly synthesized DHFs can be included along with other flavonoids while attempting clinical trial for analgesic use.

Acetates↗
PubMed1988

Phase I and clinical pharmacology study of intravenous flavone acetic acid (NSC 347512).

We have conducted a Phase I and pharmacological study of flavone acetic acid, one of a series of novel flavonoids. The drug was administered i.v. weekly for 4 weeks, with a 2-week rest and then repeated. Flavone acetic acid was given initially in a 1-h infusion, but at the 3900-mg/m2 dose level, the infusion time was lengthened to 3 h. A total of 31 patients were treated with 9 different dose levels, ranging from 330 to 6400 mg/m2. Dose-limiting toxicity was acute hypotension that began after about one-third of each drug dose had been infused and rarely lasted more than a few minutes after the infusion was discontinued. In addition, subjective fatigue and asthenia causing unacceptable patient discomfort was dose limiting. A significant side effect noted that was not dose limiting was diarrhea during the infusion. This drug exhibited nonlinear pharmacokinetic behavior. Plasma levels exceeded 300 micrograms/ml during the infusion at the maximally tolerated dose. After the infusion ended the principal half-life was about 2 h. In 24-h urine collections 27% of the flavone acetic acid dose was recovered as intact drug and an additional 37% was recovered as a metabolite. The maximally tolerated dose determined in this study is 6400 mg/m2 given i.v. over 3 h.

Adult↗
PubMed1986

Flavone acetic acid: a novel agent with preclinical antitumor activity against colon adenocarcinoma 38 in mice.

Flavone acetic acid, given on Days 2 and 9 at a dose of 267 mg/kg, inhibited tumor growth completely in 60%-80% of mice with early-stage Colon Adenocarcinoma 38. The therapeutic efficacy of the flavone against this tumor was retained when the sites of tumor implantation and drug administration were separated. Flavone acetic acid also caused regression of advanced (500-mg) Colon 38 tumors, with greatest efficacy observed following administration of high individual dose rather than high total dose. Unlike many previous potential anticancer agents, only modest activity was observed for this compound against either P388 or L1210 leukemia.

Adenocarcinoma↗
PubMed2006

Iridoid glucosides and flavones from the aerial parts of Avicennia marina.

Two new iridoid glucosides, namely, 2'-O-[(2E,4E)-5-phenylpenta-2,4-dienoyl]mussaenosidic acid (1; mussaenosidic acid = [1S-(1alpha,4aalpha,7alpha,7aalpha)]-1-(beta-D-glucopyranosyloxy)-1,4a,5,6,7,7a-hexahydro-7-hydroxy-7-methylcyclopenta[c]pyran-4-carboxylic acid) and 2'-O-(4-methoxycinnamoyl)mussaenosidic acid (2), were isolated from the aerial parts of the mangrove plant Avicennia marina. Beside that, one known iridoid glucoside, 2'-O-coumaroylmussaenosidic acid (3) and four known flavones (flavone = 2-phenyl-4H-1-benzopyran-4-one) including 4',5-dihydroxy-3',7-dimethoxyflavone (4), 4',5-dihydroxy-3',5',7-trimethoxyflavone (5), 4',5,7-trihydroxyflavone (6), and 3',4',5-trihydroxy-7-methoxyflavone (7) were also isolated and identified. The structures of these compounds were elucidated by NMR spectroscopy and by low- and high-resolution mass spectrometry. The chemotaxonomic significance of these findings was discussed. In addition, each isolated compound was evaluated for the ability of alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical-scavenging activity.

Avicennia↗
PubMed2005

Novel nonaqueous capillary electrophoresis separation and determination of bioactive flavone derivatives in Chinese herbs.

Nonaqueous CE (NACE) coupled to UV detection is described for the separation and determination of bioactive flavone derivatives in Chinese herbs extraction. After optimization of electrophoresis parameters, including the electrolyte nature and the organic solvent composition, a reliable separation of the analytes in an ACN/methanol (60:40, v/v) mixture containing 80 mM Tris and 10 mM sodium cholate was performed. The detection was performed at 254 nm. Method performances, including migration time and peak area reproducibility, linearity, sensitivity, and accuracy, were evaluated. The method was applied to determine bioactive flavone derivatives in seven Chinese herbs.

Drugs, Chinese Herbal↗
PubMed2004

Inhibition of nitric oxide production from lipopolysaccharide-treated RAW 264.7 cells by synthetic flavones: structure-activity relationship and action mechanism.

Recent investigations have shown that certain flavonoids, especially flavone derivatives, inhibit nitric oxide (NO) production by inducible NO synthase (iNOS) in macrophages, which contribute their anti-inflammatory action. For the purpose of finding the optimized chemical structures of flavonoids that inhibit NO production, various A- and B-ring substituted flavones were synthesized and evaluated for their inhibitory activity using lipopolysaccharide-treated RAW 264.7 cells. It was found that the optimal chemical structures were A-ring 5,7-dihydroxyflavones having the B-ring 2',3'-dihydroxy or 3',4'-dihydroxy or 3',4'-hydroxy/methoxy (methoxy/hydroxy) groups. These structurally optimized compounds were revealed to be down-regulators of iNOS induction, but not direct iNOS inhibitors. Of these derivatives that were evaluated, 2',3',5,7-tetrahydroxyflavone and 3',4',5,7-tetrahydroxyflavone (luteolin) showed the strongest inhibition. The IC50 values for these compounds were 19.7 and 17.1 microM, respectively. Therefore, these compounds may have a potential as new anti-inflammatory agents.

Animals↗
PubMed2005

Increased mitochondrial palmitoylcarnitine/carnitine countertransport by flavone causes oxidative stress and apoptosis in colon cancer cells.

Cancer cell metabolism is characterized by limited oxidative phosphorylation in order to minimize oxidative stress. We have previously shown that the flavonoid flavone in HT-29 colon cancer cells increases the uptake of pyruvate or lactate into mitochondria, which is followed by an increase in O(2) (-.). production that finally leads to apoptosis. Similarly, a supply of palmitoylcarnitine in combination with carnitine induces apoptosis in HT-29 cells by increasing the mitochondrial respiration rate. Here we show that flavone-induced apoptosis is increased more than twofold in the presence of palmitoylcarnitine due to increased mitochondrial fatty acid transport and the subsequent metabolic generation of O(2) (-.) in mitochondria is the initiating factor for the execution of apoptosis.

Apoptosis↗
PubMed1993

Flavone photoreactivity. UV-induced reactions in organic solvents and micellar systems.

Flavonoid photochemistry is a subject of interest in studies dealing with the role of phenolic compounds as screening pigments in plants. In order to contribute to the understanding of the processes involved in the interaction between flavonoids and UV radiation, we have studied UV-induced flavone photodegradation in both organic solvents and micellar systems. The results obtained show that flavone photosensitivity depends on the characteristics of the reaction environment and is influenced by the medium polarity and the charges on the micellar surface. Qualitative and quantitative differences in the photodegradation products were demonstrated by high performance liquid chromatography (HPLC) analysis.

Chromatography, High Pressure Liquid↗
PubMed2004

Design, synthesis, and alpha(1)-adrenoceptor binding properties of new arylpiperazine derivatives bearing a flavone nucleus as the terminal heterocyclic molecular portion.

Following our research project aimed at obtaining new compounds with high affinity and selectivity toward alpha(1)-adrenoceptors (AR), a new class of piperazine derivatives was designed, synthesized and biologically tested. The new compounds 1-13 are characterized by a flavone system linked, through an ethoxy or propoxy spacer, to a phenyl- or pyridazinone-piperazine moiety. Biological data showed an interesting profile for the phenylpiperazine subclass found to have a nanomolar affinity toward alpha(1)-AR, and less pronounced affinity for alpha(2)-AR and the 5-HT(1A) serotoninergic receptor. A discussion on the structure-activity relationship (SAR) of such compounds is also reported, on the basis of the flavone substitution pattern, length and functionalization of the spacer, and disruption of the phenylpiperazine system.

Adrenergic alpha-Antagonists↗
PubMed2005

Synthesis and biological evaluation of a series of flavone derivatives as potential radioligands for imaging the multidrug resistance-associated protein 1 (ABCC1/MRP1).

Multidrug resistance (MDR) is one of the major problems affecting the treatment of cancer. In vivo visualization and quantification of MDR proteins would be of great value to better select the therapeutic strategy. Six flavone-based compounds were synthesized and evaluated for their cytotoxic activity and MDR-reversing capacity using hMRP1 or hMDR1 overexpressing cell lines for in vitro assays. All the flavone derivatives were highly selective for hMRP1-expressing cell lines. These derivatives each used at 4muM (a non-cytotoxic concentration) enhance significantly the sensitivity of hMRP1-mediated MDR cell line toward doxorubicin toxicity. Their MDR-reversing capacity suggests that, in particular, the 4'-fluoroalkyloxy and 4'-iodo apigenin derivatives are potential new radiopharmaceuticals to visualize in vivo MRP1-mediated MDR phenomenon by PET or SPECT.

Apigenin↗
PubMed2006

Synthesis and antibacterial activity of substituted flavones, 4-thioflavones and 4-iminoflavones.

Synthesis of flavones, 4-thioflavones and 4-iminoflavones was carried out with the substitution of variable halogens, methyl, methoxy and nitro groups in the A, B and AB rings of the respective compounds and we also report here their antibacterial activity. Most of the synthesized compounds were found to be active against Escherichia coli, Bacillus subtilis, Shigella flexnari, Salmonella aureus, Salmonella typhi and Pseudomonas aeruginosa. Activity of 4-thioflavones and 4-iminoflavones was found to be higher than that of their corresponding flavone analogues. Investigated compounds having substituents like F, OMe and NO2 at 4'-position in ring-B exhibited enhanced activity and the presence of electronegative groups in the studied compounds showed a direct relationship to the antibacterial activity.

Anti-Bacterial Agents↗
PubMed2004

Neuroprotective effects of flavones on hydrogen peroxide-induced apoptosis in SH-SY5Y neuroblostoma cells.

Neuroprotective effects of flavones were examined. Luteolin and apigenin exhibited neuroprotection against oxidative stress-induced cell death in SH-SY5Y cells. Free radical scavenging activity and neuroprotection assays revealed that flavones exerted their neuroprotective effects via the direct interaction with the apoptotic caspase pathway independently of their antioxidant activity.

Apoptosis↗
PubMed2005

Total synthesis and bioactivity of unique flavone desmosdumotin B and its analogs.

The first total synthesis of a unique flavone natural product, desmosdumotin B (1), was accomplished. Furthermore, three novel flavonoids, 6-8, and a novel chalcone, 9, were synthesized. The new compounds were evaluated as in vitro inhibitors of human cancer cell growth. The synthetic 1 showed significant cytotoxic activity against a multi-drug resistant cell line (KB-VIN) with an ED50 value of 2.0 microg/mL compared to >40 microg/mL against the parental KB cell line. Flavone 7 displayed selective activity against 1A9 ovarian carcinoma with an ED50 value of 0.7 microg/mL. Selected 1-analogs and synthetic intermediates were also screened for antitumor-promoting effects as inhibitors of EBV-EA activation. Among them, trihydroxyacetophenone derivatives 11 and 14 showed good activity.

Alkenes↗
PubMed2006

Synthesis and antimalarial evaluation of a series of piperazinyl flavones.

A series of 27 flavonoid derivatives containing a piperazinyl chain have been synthesized and tested for their antiplasmodial activity. Diverse substitution patterns on piperazinyl and flavone moieties were examined and found to affect the activity differently. The most active compounds, which have a 2,3,4-trimethoxybenzylpiperazinyl chain attached to the flavone at the 7-phenol group, showed in vitro activity against chloroquine-sensitive (Thai) and -resistant (FcB1,K1) Plasmodium falciparum strains in the micromolar to submicromolar range. One of them was active when given orally in a Plasmodium yoelii nigeriensis infected mouse model.

Animals↗