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At least 19 recordsLinked to original sources
PubMed1975

[Flavonols and flavones of vegetables. V. Flavonols and flavones of root vegetables (author's transl)].

Root vegetables contain flavon(ol) glycosides in tracers up to small amounts, while the level of their leaves are in part considerable (to more than 1 g/kg, calculated as aglycon). Radish, rutabagas, scorzoneras, and beets contain less than 1 mg/kg kaempferol and/or quercetin; carrots less than 1 mg/kg apigenin and luteolin; celery roots ca. 75 mg apigenin/kg and 14 mg luteolin/kg; horseradish about 20 mg kaempferol/kg and small radish 1-10 mg kaempferol/kg, whereby all these flavones and flavonols occur as glycosides in the vegetables. In leaves of small radish, variety "Eiszapfen", we found besides isoquercitrin (quercetin-3-glucoside) a quercetin-3-0-diglycoside and a kaempferol-0-diglycoside, both with the sugars rhamnose and arabinose, by tlc.

Arabinose↗
PubMed1977

[Flavonols and flavones of vegetables. VIII. Flavones of carrot leaves (author's transl)].

The flavonoid constituents of carrot leaves (Daucus carota L. ssp. sativa) were separated by means of cellulose column chromatography, and the following compounds were obtained crystalline and identified by usual procedures: luteolin 7-beta-D-glucoside as the main flavon, luteolin 4'-beta-D-glucoside, luteolin 7-beta-D-glucuronide, apigenin 7-beta-D-glucoside, apigenin 7-rutinoside, chrysoeriol 7-beta-D-glucoside. Luteolin 7-rutinoside also was identified, but could not be obtained crystalline.

Chromatography↗
PubMed1977

[Isolation and identification of flavon(ol)-O-glycosides in caraway (Carum carvi L.), fennel (Foeniculum vulgare Mill.), anise (Pimpinella anisum L.), and coriander (Coriandrum sativum L.), and of flavon-C-glycosides in anise. I. Phenolics of spices (author's transl)].

The flavonoid constituents of various spices were separated by means of chromatography on cellulose colums, and the following compounds were obtained crystalline: Quercetin 3-glucuronide from caraway, fennel, anise, and coriander; isoquercitrin from caraway and fennel; rutin from fennel and anise; quercetin 3-O-caffeylglucoside and kaempferol 3-glucoside from caraway; quercetin 3-arabinoside from fennel, and luteolin 7-glucoside, isoorientin and isovitexin from anise. Other constitutents which were however not obtained crystalline, but which could be identified by the usual procedures were kaempferol 3-glucuronide and kaempferol 3-arabinoside in fennel, apigenin 7-glucoside and a luteolin glycoside in anise, and isoquercitrin and rutin in coriander. The glycosides contained in the fruit of the four spices also occur in the leaves. Leaves of caraway and fennel in addition contain isorhammetin glycosides in low concentration.

Condiments↗
PubMed1990

Purification and characterization of flavone synthase I, a 2-oxoglutarate-dependent desaturase.

Soluble flavone synthase I from illuminated parsley cells was purified to near homogeneity by a six-step procedure. A molecular mass of 48 +/- 2 kDa was determined by gel permeation chromatography and denaturing polyacrylamide gel electrophoresis. A single protein with an isoelectric point at pH 4.8 +/- 0.1 was detected on isoelectric focusing gels, which catalyzed the overall conversion of 2S-flavanones into the corresponding flavones in the presence of molecular oxygen, 2-oxoglutarate, ferrous ion, and ascorbate. Apparent Michaelis constants for 2S-naringenin, 2S-eriodictyol, and 2-oxoglutarate were determined as 5, 8, and 16 microM, respectively. (+)-Dihydrokaempferol and 2R-naringenin were not accepted as substrates. The enzyme was strongly inhibited by Cu2+ and Zn2+. Potent competitive inhibition with respect to 2-oxoglutarate was observed with 2,4-pyridinedicarboxylate (Ki = 1.8 microM). With crude extracts as well as with the purified enzyme neither the hypothetical intermediate 2-hydroxyflavanone nor a dehydratase activity capable of converting the chemically synthesized compound to flavone could be observed. Moreover, the introduction of the double bond into the substrate naringenin was not altered by addition of chemically synthesized 2-hydroxynaringenin into the reaction mixture. Therefore, 2-hydroxyflavanones are apparently not freely dissociable intermediates in the biosynthesis of flavones in parsley and are not capable of entering the active site of the enzyme to compete with the flavanone. It is postulated that flavone synthase I catalyzes double-bond formation by direct abstraction of vicinal hydrogen atoms at C-2 and C-3 of the substrate. Thus, flavone synthase I is a member of a novel subgroup within the 2-oxoglutarate-dependent dioxygenases that can be referred to as 2-oxoglutarate-dependent desaturases.

Carbon Radioisotopes↗
PubMedDate not supplied

Inhibition of ethoxy- and pentoxy-resorufin dealkylases of rat liver by flavones and flavonols: structure-activity relationship.

The inhibitory effects of 17 flavones and flavonols on ethoxy- and pentoxy-resorufin dealkylases of rat liver were investigated. Several findings concerning the relationship between structure and activity can be pointed out. The presence or lack of hydroxyl groups on the flavane nucleus has no influence on the efficiency of inhibition. Flavone and quercetin result in the same degree of inhibition. For polyhydroxylated moleculse, the position of hydroxyl groups on A and B rings was an important factor. The more powerful inhibitors were the flavones having hydroxyl groups only on the A ring (e.g. chrysin) and the inhibitory effect was decreased by addition of hydroxyl substituents on the B group (e.g. quercetin). EROD activities were more responsive than PROD activities. Flavone and quercetin were competitive inhibitors of EROD activity whereas chrysin and morin were mixed type inhibitors. In the case of PROD activity, all four flavones were of the mixed type inhibitors.

Animals↗
PubMed2026

Flavones in osteosarcoma: Molecular mechanisms, antitumor activity, and translational challenges.

Osteosarcoma remains the most common primary malignant bone tumor, and survival has improved little over recent decades because of metastasis and therapeutic resistance. Flavones exhibit diverse anti-osteosarcoma activities by suppressing proliferation, inducing apoptosis, ferroptosis and autophagy, inhibiting metastasis, and modulating oncogenic signaling pathways, including PI3K-Akt, Wnt-β-catenin, STAT3, MAPK, and NF-κB. This review summarizes the cell-line-specific molecular mechanisms of representative flavones, critically evaluates current experimental limitations, and discusses strategies to improve clinical translation through nanotechnology-based delivery and combination therapy. Although clinical evidence remains lacking, flavones represent promising adjunctive candidates for overcoming chemoresistance and improving osteosarcoma treatment.

apoptosis and metastasis↗
PubMed1990

Microbiological transformation of flavone and isoflavone.

1. Flavone and isoflavone were subjected to microbial transformation studies. Screening with 80 fungal species showed that flavone was transformed by a large number of microorganisms and in higher yields than isoflavone. 2. Large-scale fermentations of flavone followed by isolation and characterization of metabolites using spectroscopic analysis showed the formation of 4'-hydroxyflavone, 3',4'-dihydroxyflavone and two cleavage products identified as o-hydroxyphenyl-hydroxymethyl ketone and 1-(o-hydroxyphenyl)-1,2-ethanediol. However, fermentation of isoflavone gave only 4'-hydroxyisoflavone and 3',4'-dihydroxyisoflavone.

Biotransformation↗
PubMed1992

Flavones are inhibitors of HIV-1 proteinase.

Substituted gamma-chromones were found to weakly inhibit HIV-1 proteinase, an important enzyme in the replication and processing of the AIDS virus. Chromones bearing hydroxyl substituents and a phenolic group at the 2-position (flavones) were the most active compounds and structure-activity relationships for a limited series of flavone inhibitors are presented. Dixon plots are reported and a possible mechanism for flavone-induced inhibition is proposed. The results are also compared with those for some structurally related non-peptidic inhibitors of HIV-1 proteinase. Since some flavonoid compounds have already been shown to have antiviral activity against AIDS, the present observations of anti-HIV-1 proteinase activity may be particularly significant.

Chromones↗
PubMed1992

Organotin-flavone complexes: a new class of fluorescent probes for F1F0ATPase.

Fluorescent 5-coordinate organotin-flavone complexes of 3-hydroxy-flavone (Hof) and 3,5,7,2',4',-pentahydroxyflavone (morin) are good inhibitors of mitochondrial F1F0ATPase but do not inhibit F1-ATPase and they have been examined as possible fluorescent probes of F1F0ATPase. R2SnX (morin) complexes exhibit low fluorescence enhancement on binding to mitochondrial membranes with no displacement by equimolar tributyltin. In contrast R2SnX (of) complexes exhibit high fluorescence enhancement whose extent is variable and is displacable by equimolar tributyltin. Fluorescence enhancement by R2SnX (of) complexes correlates with the ATPase I50 values. Dialkyltin-3-hydroxy flavone, R2SnX(of), complexes act as a new class of fluorescent probes which titrate the F0 segment of F1F0ATPase.

Animals↗
PubMed1990

Analgesic activity of certain flavone derivatives: a structure-activity study.

Flavone and 10 hydroxy and glucoside flavone derivatives were synthesised. They were tested for their analgesic effect in mice employing acetic acid-induced writhing and tail immersion methods. Subcutaneously all the tested compounds exhibited significant analgesic activity with varying potencies in both assay models. The activity of flavone and its 5-; 7-; 2'-; 5,7- and 7,8-hydroxy derivatives apparently involves an opiate-like mechanism, since their activity was reversed by naloxone pretreatment. It is suggested that flavonoid substances may utilise more than one mechanism in eliciting analgesia.

Analgesics↗
PubMed1992

Site-specific DNA cleavage by mammalian DNA topoisomerase II induced by novel flavone and catechin derivatives.

Four naturally occurring flavones (baicalein, quercetin, quercetagetin and myricetin) and two novel catechins [(-)-epicatechin gallate and (-)-epigallocatechin gallate, from the tea plant Camellia sinensis], which are known inhibitors of reverse transcriptase, were shown to induce mammalian topoisomerase II-dependent DNA-cleavage in vitro. The flavones differed from the catechins in causing unwinding of duplex DNA, but both classes of compound induced enzymic DNA breakage at the same sites on DNA. Moreover, the cleavage specificity was the same as that for the known intercalator 4'-(acridin-9-ylamino)methanesulphon-m-anisidide, suggesting that these agents trap the same cleavable complex. Analysis of some 30 flavonoid compounds allowed elucidation of the structure-function relationships for topoisomerase II-mediated DNA cleavage. For flavonoid inhibitors an unsaturated double bond between positions 2 and 3 of the pyrone ring and hydroxy groups at the 5, 7, 3' and 4' positions favoured efficient cleavage. Hydroxy substitutions could be tolerated at the 3, 6 and 5' positions. Indeed, the absence of substituents at the 3', 4' and 5' positions could be compensated by a hydroxy group at position 6 (baicalein). Similar requirements have been reported for flavonoid inhibitors of protein kinase C that act competitively with ATP, suggesting interaction with a conserved protein feature. Formation of the cleavable complex is a cytotoxic lesion that may contribute to the growth-inhibitory properties of flavones observed for three human tumour cell lines. These results are discussed in regard to the selectivity of antiviral agents.

Animals↗
PubMed1992

Growth inhibition with reversible cell cycle arrest of carcinoma cells by flavone L86-8275.

BACKGROUND: Previous studies have shown that polyhydroxylated flavonoids such as quercetin and genistein can inhibit tumor cell growth in vitro, and preliminary in vivo studies of the flavone L86-8275 have shown growth inhibition of LX529 and A549 lung carcinomas. L86-8275 [(-)cis-5,7-dihydroxy-2-(2-chlorophenyl)-8[4-(3-hydroxy-1-methyl)- piperidinyl]-4H-1-benzopyran-4-one] is a flavone of novel structure. PURPOSE: The purpose of this study was to determine in vitro whether L86-8275 is a more potent inhibitor of growth in breast carcinoma and lung carcinoma cells than quercetin or genistein. METHODS: We studied the effects of L86-8275 on cell growth in seven breast carcinoma cell lines and five lung carcinoma cell lines. MDA468 breast carcinoma was then selected for further study. Cell proliferation was measured by a colorimetric dye reduction assay; synthesis of DNA, RNA, and protein by incorporation of the radioactive metabolic precursors thymidine, uridine, or leucine, respectively; adenosine triphosphate (ATP) content by a luciferase-mediated bioluminescence reaction; and cell cycle progression by the use of cell-synchronizing drugs (aphidicolin and nocodazole) and flow cytometry. RESULTS: L86-8275 was not cytotoxic to stationary-phase cells but reversibly inhibited the growth of cells in exponential growth phase. At concentrations of 25-160 nM, L86-8275 inhibited growth of human breast and lung carcinoma cell lines by 50%. MDA468 breast carcinoma cells were 60-fold and 400-fold more sensitive to L86-8275 than to quercetin and genistein, respectively. By 24 hours after addition of L86-8275, DNA synthesis in MDA468 cells was inhibited by greater than 95%, protein synthesis by 80%, and RNA synthesis by 40%-60%, under conditions that preserved cellular ATP levels at approximately 80%-90% of control values. When MDA468 cells released from aphidicolin-induced cell cycle arrest were exposed to 200 nM L86-8275, they completed the S phase but arrested in G2. When cells released from nocodazole-induced cell cycle arrest were exposed to 200 nM L86-8275, they completed mitosis but arrested in G1. CONCLUSIONS: L86-8275 is a potent, yet reversible, growth-inhibitory flavone that can selectively block cell cycle progression in vitro at more than one point in the cell cycle. IMPLICATIONS: These findings suggest that L86-8275 is a candidate for further preclinical development, as well as a model for the synthesis of other flavonoids that might potently delay cell cycle progression to achieve inhibition of tumor growth. Future studies need to address optimal schedules for antiproliferative activity in vivo and inhibition of clonogenic activity.

Adenosine Triphosphate↗
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↗
PubMed1975

Isolation and identification of three new flavones from Achillea millefolium L.

Column chromatography on silica gel of a petroleum ether extract of the flowering heads of Achillea millefolium L. allowed three flavones to be separated and identified. Spectral studies (PMR, mass spectrometry, and UV) and a comparison with data for compounds reported in the literature established the flavones as 5-hydroxy-3,6,7,4'-tetramethoxyflavone, artemetin, and casticin. These compounds have not been reported previously as constituents of A. millefolium.

Flavonoids↗
PubMed1989

Comparison of the effects of flavone acetic acid, fostriecin, homoharringtonine and tumour necrosis factor alpha on colon 38 tumours in mice.

Advanced subcutaneous Colon 38 tumours in mice were used for the assessment of activity of a number of anticancer drugs. Activity was measured by histological examination of tumours 24 h after a single dose of the drug and in some cases by tumour growth delay. Agents thought to exert their cytotoxic effect by damaging DNA, including Adriamycin, amsacrine and its analogue CI-921, cyclophosphamide, 5-fluorouracil and methotrexate produced no gross histological changes after 24 h, even though some delayed the growth of subcutaneous tumours. In contrast, flavone acetic acid, fostriecin and homoharringtonine caused extensive necrosis of tumours after 24 h, and each delayed the growth of advanced subcutaneous tumours by at least 10 days when administered as a single dose. The histological effects of flavone acetic acid and fostriecin were indistinguishable from those of recombinant human tumour necrosis factor alpha. It is proposed that histological assay of advanced tumours may provide a useful adjunct to existing methods in screening for antitumour agents with novel mechanisms of action.

Alkaloids↗
PubMed1992

A comparison of vascular-mediated tumor cell death by the necrotizing agents GR63178 and flavone acetic acid.

A vascular component of tumor damage has been identified for the anticancer agent GR63178. The necrotizing activity of this drug and of flavone acetic acid has been compared with their ability to induce growth delay in six murine tumor models. At 24 hr, after a fixed dose of flavone acetic acid (200 mg/kg), all six tumor types appeared 80-100% necrotic histologically, although growth delays ranging from 3 to 79 days were measured. GR63178 (200 mg/kg) induced more variable degrees of necrosis (10 to 95%), but a uniformly small delay in growth (0 to 4 days). These data illustrate that the absence of a tumor-growth response should not be automatically equated with an absence of drug activity. Without assessing tumor response histologically, agents with unusual mechanisms of action may be missed, despite their potential for killing large numbers of tumor cells.

Animals↗
PubMed1992

Scavenger and antioxidant properties of ten synthetic flavones.

To study the effect of the hydroxyl groups on biological activities of flavones, we synthesized 10 polyhydroxyflavones with varied substitution patterns. The abilities of the 10 compounds to act as radical scavengers were investigated using chemiluminescence in two biological models: the xanthine/xanthine oxidase system and the oxidative burst of rat alveolar macrophages. Stable radical formation was observed by electron spin resonance (ESR) spectroscopy. We found that the presence of the pyrogallol moiety in the B component of flavones gave rise to radical scavenger activity and that C-6 substituted hydroxyl group may also provide the basis for biological activity. Furthermore, compounds with a hydroxyl at C-7 position appeared to be xanthine oxidase inhibitors. One particular compound exhibited radical scavenger activity and xanthine oxidase inhibition. This type of compound should prove to be useful in the treatment of ischemia, for which both properties were required.

Animals↗