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PubMed2003

Hepatoprotective effect of baicalin, a major flavone from Scutellaria radix, on acetaminophen-induced liver injury in mice.

The protective effects of baicalin (BA), a major flavone from Scutellaria radix, on acetaminophen (AP)-induced hepatotoxicity and the possible mechanism(s) of its protective action were investigated in mice. Treatment with BA (300 mg/kg, p.o.) 0.5 h after AP administration significantly prevented an increase in plasma alanine aminotransferase and aspartate aminotransferase activities and AP-induced hepatic necrosis, and also reduced AP-induced mortality from 43% to 0%. In addition, oral treatment with BA significantly prevented AP-induced depletion of glutathione (GSH) contents. However, BA treatment, by itself, did not affect hepatic GSH contents. The effect of BA on the cytochrome P450 2E1 (CYP2E1), the major isozyme involved in AP bioactivation, was investigated. Oral treatment of mice with BA resulted in a significant decrease in AP-induced CYP2E1 activity together with its inhibition of AP-induced CYP2EI expression. These results show that the hepatoprotective effects of BA against AP overdose may be due to its ability to block the bioactivation of AP by inhibiting CYP2E1 expression.

Acetaminophen↗
PubMed1984

Inhibition of aflatoxin B1 carcinogenesis in rainbow trout by flavone and indole compounds.

Several compounds such as flavonoids, selenium, antioxidants and retinoids reportedly reduce the induction of cancer in experimental animals, and some have been suggested to function by affecting the mixed-function oxidase (MFO) system. The following compounds: 50 and 500 p.p.m. beta-naphthoflavone (BNF), 1000 p.p.m. flavone, 1000 p.p.m. of a tangeretin - nobilitin mixture, 1000 p.p.m. beta- ionone , 1000 p.p.m. indole-3-carbinol ( I3C ) and 2000 p.p.m. quercetin were examined for protection against aflatoxin B1 (AFB1) hepatocarcinogenesis, induction of the MFO system and metabolism of AFB1 in rainbow trout. These compounds were fed to fingerling rainbow trout for 8 weeks. At that time the activity of several MFO enzymes and cytochrome P450 content were measured and the trout were exposed for 2 weeks to 20 p.p.b. AFB1 in the same diets. After feeding the test diets without AFB1 for another 6 weeks and basal diet for another 52 weeks, the tumor incidence was determined. The effect of BNF and I3C on in vivo binding of AFB1 to DNA was also measured in separate groups of trout. BNF induced the trout MFO system in a dose-dependent manner, tangeretin - nobilitin was less effective and I3C did not induce. BNF showed significant alterations in the metabolism of AFB1 to aflatoxicol and aflatoxin M1 using cell fractions from pretreated fish. None of the other compounds, including I3C showed such an effect. Despite the apparent lack of in vitro effect of I3C , both BNF and I3C reduced AFB1 - DNA binding in vivo. I3C and BNF provided marked protection against AFB1-induced hepatocarcinogenesis, while the other compounds were less effective. The 58 weeks tumor incidences were 4% for 1000 p.p.m. I3C , 6% for 500 p.p.m. BNF and 18% for 50 p.p.m. BNF, compared to 38% for the AFB1-positive control. These data demonstrate that gross induction of the MFO system was not necessarily required for alterations in DNA adduct formation in vivo or protection against AFB1 carcinogenesis. Both BNF and I3C provided marked protection but only BNF induced the MFO system.

Aflatoxin B1↗
PubMed1985

Effects of ellipticine, flavone, and 7,8-benzoflavone upon 7,12-dimethylbenz[a]anthracene, 7,14-dimethyldibenzo[a,h]anthracene and dibenzo[a,h]anthracene initiated skin tumors in mice.

Varying doses of ellipticine (EL), flavone (FL), or 7,8-benzoflavone (78BF) were applied to mouse skin 5 min before an initiating dose of 10 nmol 7,12-dimethylbenz[a]anthracene (DMBA), 47.5 nmol 7,14-dimethylbenzo[a,h]anthracene (DDBA), or 200 nmol dibenzo[a,h]anthracene (DBA) and the development of skin tumors in the mice then promoted by topical applications of 2 micrograms 12-O-tetradecanoylphorbol-13-acetate (TPA). As expected, treatment with 78BF (37 nmol or 370 nmol) markedly inhibited the skin tumor initiation by DMBA (greater than 70%). High doses of FL (4500 nmol) or EL (410 nmol) also inhibited DMBA tumorigenesis (52% and 82%, respectively) but lower doses of FL (450 nmol) or EL (4.1 nmol) stimulated DMBA tumorigenesis (greater than 40%). As was the case with DMBA initiation, the higher doses of FL or EL inhibited DDBA skin tumorigenesis and the lower doses of these two modifiers stimulated the DDBA tumorigenesis. In contrast with the results with DMBA initiation, treatment with 78BF (370 nmol or 3700 nmol) slightly enhanced DDBA tumorigenesis (22% and 6%, respectively). Treatment with EL and FL at all doses tested stimulated DBA tumorigenesis (range 4-51%), while treatment with 370 nmol 78BF slightly stimulated DBA tumorigenesis (19%) and treatment with 3700 nmol slightly inhibited DBA tumorigensis (9%). The effects of a range of 78BF doses upon skin tumor initiation by 40 nmol DMBA were also investigated. While all doses of 78BF tested (0.37-370 nmol) inhibited the DMBA tumorigenesis, the dose response was not linear; treatment with 3.7 nmol 78BF resulted in more papillomas per mouse (12.20) than did treatment with either 0.37 nmol 78BF (8.70) or 37 nmol 78BF (5.97). It is concluded that modifiers such as 78BF, FL and EL may have a variable, dose-dependent effect upon skin tumor initiation by carcinogenic polycyclic arylhydrocarbons. Some implications of this proposal are discussed.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1988

C18 solid-phase isolation and high-performance liquid chromatography/ultraviolet diode array determination of fully methoxylated flavones in citrus juices.

A new analytical methodology for the determination of fully methoxylated flavones (FMFs) in citrus juices is described. Isolation of the FMFs is carried out by percolation of 30 mL of clarified citrus juice (to which tetramethyl-o-kaempferol is previously added as internal standard) through a C18 Sep-Pak cartridge, washing with 3 mL of water followed by 5 mL of water/acetonitrile (3:1), and selective elution of the retained FMFs with 5 mL of water/acetonitrile (9:11). Determination of the isolated FMFs is carried out by reversed-phase high-performance liquid chromatography (HPLC) and UV diode array detection (DAD). Signals at wavelengths 320, 335, and 345 nm (bandwidth 4 nm) are simultaneously acquired, stored, plotted, and integrated. The column used is a microbore (200 x 2.1-mm) Hypersil ODS 5 microns. Elution is in gradient mode, using a ternary mobile phase (water/acetonitrile/tetrahydrofuran). Column temperature is 40 degrees C. Recovery yields are nearly 100% for all the FMFs detected and identified: isosinensetin, hexamethyl-o-gossypetin, sinensetin, tetramethyl-o-isoscutellarein, hexamethyl-o-quercetagetin, nobiletin, tetramethyl-o-scutellarein, heptamethoxyflavone, and tangeretin. Chromatographic separation of the FMFs is extremely dependent upon the minor changes of the mobile phase composition and percentages, gradient rate, and temperature. The UV spectra (230 to 400 nm) of the FMFs obtained under chromatographic conditions are given. The FMFs relative response factors at 320, 335, and 345 nm and their concentrations in hand-squeezed and commercial concentrated orange and mandarin juices are tabulated. The FMF concentration differences found among samples are discussed.

Beverages↗
PubMed1988

Immunomodulation of natural killer cell activity by flavone acetic acid: occurrence via induction of interferon alpha/beta.

The investigational drug flavone acetic acid (FAA) systemically augments natural killer (NK) cell activity in normal and tumor-bearing mice and in human cancer patients. The results from the present investigation demonstrate that in vivo administration of FAA induces in a dose-dependent manner high levels of serum interferon (IFN) within 4 hours in BALB/c, C57BL/6, and BALB/c nude mice. Antibody neutralization studies indicated that FAA induced IFN of the alpha/beta type, while molecular hybridization studies demonstrated that FAA rapidly stimulated the production of IFN alpha mRNA in splenic leukocytes. In vivo administration of anti-IFN alpha/beta antibodies to FAA-treated mice inhibited the FAA-induced augmentation of splenic NK cell activity at 4 hours. These results suggest that FAA mediates its anti-tumor effects indirectly by immunomodulation as well as directly by antiproliferative or cytotoxic activity.

Adjuvants, Immunologic↗
PubMed1988

Effect of flavone acetic acid on Lewis lung carcinoma: evidence for an indirect effect.

Flavone-8-acetic acid (FAA), a new antitumor agent currently undergoing clinical trial, fails to inhibit the growth of early stage Lewis lung (LL) tumors growing in the lung. However, the growth of advanced subcutaneous tumors, arising from inoculation of either the original in vivo LL line or a tissue culture-adapted cell line (LLTC) derived from the LL line was delayed significantly by FAA treatment. Comparison, by clonogenic survival assays, of the cytotoxic effect of FAA on LLTC cells demonstrated that most cell killing occurred between 2 and 8 hours following in vivo exposure but occurred to a much lesser extent and at later times following in vitro exposure. FAA was inactive against LLTC cells growing in vivo in diffusion chambers, suggesting that a host cellular component was necessary for activity. FAA was found to induce hemorrhagic necrosis in the advanced LL tumors, as well as in a number of human tumor xenografts growing in athymic mice. The human cell lines from which the xenografts were derived, as well as the LL tumor lines and P388 leukemia lines, were inhibited by FAA in vitro. However, the ranking of FAA activity in vivo did not parallel that observed in vitro. Together, these observations strongly suggest that FAA has an indirect mode of antitumor action.

Animals↗
PubMed1989

Blood flow failure as a major determinant in the antitumor action of flavone acetic acid.

Some investigators have suggested that the marked activity of flavone acetic acid (FAA) against advanced solid tumors in mice results from an indirect effect. This study indicates that the critical effect of FAA is irreversible inhibition of tumor blood flow. Perfusion of sc Colon 38 tumors, assessed with H33342 as a fluorescent stain for functional blood vessels, was reduced to 50% of controls within 3 hours of an ip injection of 1.2 mmol of FAA/kg and was completely inhibited by 24 hours. A double-label fluorescence technique demonstrated a significant decrease in blood flow in both sc Colon 38 and im EMT-6/Ak tumors as early as 15 minutes after iv treatment with 1.2 mmol of FAA/kg, with progressively enlarging zones of perfusion failure. The rate of cell death in totally ischemic EMT-6 tumors was shown to be sufficiently rapid to represent a major component of the observed antitumor effect of FAA if the flavonoid acts via inhibition of blood flow. Further, avascular EMT-6/Ak multicellular spheroids growing in the mouse peritoneum are relatively resistant to killing by FAA administered iv or ip, despite extensive infiltration with host immune cells. These results indicate that inhibition of tumor blood flow by FAA is a necessary component of its antitumor activity against solid tumors.

Animals↗
PubMed1989

Reduction of tumor blood flow by flavone acetic acid: a possible component of therapy.

Flavone acetic acid (FAA) is active against normally refractory murine sc tumors. Clinical studies are disappointing despite achievement of plasma profiles associated with the antitumor murine activity in man. To clarify the mechanism of action, we have followed histologic changes, tumor blood volume, and drug concentrations in a well-differentiated, slow-growing cystic adenocarcinoma in mice. FAA causes massive tumor necrosis beginning 2 hours after treatment. Tumor plasma volumes are reduced by 2 hours after treatment and tumor blood vessels are shutdown, which suggests that tumor vasculature plays a role in the dramatic response of sc tumors in pure-strain male NMRI mice.

Adenocarcinoma↗
PubMed1991

Natural killer (NK) and lymphokine activated killer (LAK) cell activity in patients (PTS) treated with flavone acetic acid (FAA).

Natural killer (NK) cell activity was measured in nine patients with different solid tumors treated with flavone acetic acid (FAA). In three of them, NK cell activity was significantly increased, in two instances even after repeated courses of treatment. A significant increase in lymphokine activated killer (LAK) cell activity was also observed in three of four patients after in vivo treatment with FAA and in vitro incubation of lymphocytes with recombinant Interleukin-2. We observed some inter-individual variability in drug clearance, but no apparent correlation between drug plasma levels (neither peak nor AUC values) and the effects on NK and LAK activity.

Adjuvants, Immunologic↗
PubMed1991

Phase I study of flavone acetic acid (NSC 347512, LM975) in patients with pediatric malignant solid tumors.

To evaluate the anticancer agent flavone acetic acid (FAA), we conducted a Phase I trial involving 17 pediatric patients with various malignant solid tumors. Dosages investigated included 5,120 and 6,144 mg/m2 given as 3-hour intravenous infusions; and 10,000, 12,500, 15,000, and 17,500 mg/m2 delivered in a 24-hour constant infusion with alkalinization. Grade 2 or worse toxicity was minimal, with 2 patients having nausea/vomiting, 2 having diarrhea, 1 becoming hypertensive, 1 becoming hypotensive, and 2 having myalgia. Three patients who received a 17,500 mg/m2 dose had no toxicity. Disease was stabilized for a brief period in 2 patients--1 with brain stem glioma and 1 with astrocytoma. The FAA pharmacokinetics varied with an average (SD) terminal half-life of 27.9 hr (18.7), clearance of 2.04 L/hr/m2 (0.37), and steady-state volume of 19.9 L/m2 (10.6). This study was discontinued because FAA caused no significant toxicity or therapeutic responses at doses 2.5 gm/m2 greater than had been tolerated by adults.

Adolescent↗
PubMed1996

In vivo effects of tumor necrosis factor-alpha or flavone acetic acid in combination with doxorubicin on multidrug-resistant B16 melanoma.

Having observed that tumor necrosis factor (TNF)-alpha and doxorubicin (DXR) produce a synergistic inhibition of melanoma B16 and also of its multidrug resistant (MDR) variant in vitro, we tested whether this interaction would occur in vivo as well. C57BL/6 mice with s.c. tumors were treated with TNF or flavone acetic acid (FAA), a biological response modifier, in simultaneous or sequential combination with DXR. The agents were administered systemically. Overall, the results were negative, apart from a trend towards slight synergy, found in the chemosensitive melanoma, when TNF was given 1 or 2 days before DXR. The effects of FAA and DXR were found to be subadditive or antagonistic. However, an encouraging new finding was that FAA has significant inhibitory effects on the MDR B16 melanoma.

Animals↗
PubMed1997

Potentiation of the cytotoxicity of carboquone by flavone acetic acid combined with hyperthermia.

Flavone acetic acid (FAA) has shown the effectiveness of vasoactive drugs in the selective reduction of tumor blood flow. A FAA-mediated decrease in tumor blood flow may produce sufficient hypoxic conditions within the tumor. Carboquone (CQ), a naturally occurring prototype bioreductive alkylating agent like mitomycin C (MMC), has been shown to be selectively more cytotoxic toward hypoxic tumor cells. We have reported enhancement of the combined antitumor effects of MMC plus FAA and hyperthermia (HT). In this study, we examined the combined effects of FAA, CQ and HT. In vitro, although HT (43 degrees C, 60 min) reduced the colonogenicity to 0.58 in CQ (0.01 microg/ml) alone, the combined cytotoxicity of CQ and HT was not enhanced with exposure to FAA at a concentration of 100 microg/ml. In vivo, the tumor growth time, calculated as the time required to reach twice the initial tumor volume, for CQ (2 mg/kg) alone, FAA (150 mg/kg) alone, CQ+FAA, CQ+HT (43 degrees C, 15 min), FAA+HT and FAA+CQ+HT was 6.1, 5.1, 7.1, 8.0, 7.6 and 13.4 days, respectively. A significant enhancement of antitumor effects by trimodality therapy with CQ, FAA and HT was observed, when compared to the treatment with CQ and FAA (p < 0.05). The possible mechanisms of an increased antitumor response achieved with the combination of CQ, FAA and HT may be explained in the following way: the FAA-mediated decrease in tumor blood flow produced sufficient hypoxic conditions within the tumor, and these resulted in a significant increase of the antitumor effects of CQ and HT.

Animals↗
PubMed1988

Antiviral activity of flavones and potentiation by ascorbate.

We compared the anti-poliovirus activities of three flavones, quercetin, luteolin and 3-methylquercetin, which differ only at ring position 3. 3-Methylquercetin was the most potent compound. Quercetin exhibited antiviral activity only when protected against oxidative degradation by ascorbate. The antiviral activity of luteolin was comparable to that of ascorbate-stabilized quercetin.

Antiviral Agents↗
PubMed1986

A plant flavone, luteolin, induces expression of Rhizobium meliloti nodulation genes.

The symbiotic interaction of Rhizobium meliloti and alfalfa results in the formation of nitrogen-fixing root nodules. Rhizobium meliloti nodABC genes are required for the early host responses of cortical cell divisions and root hair curling. The induction of nodABC expression by alfalfa exudates demonstrates host-symbiont signaling at an early stage in nodule development. The inducer molecule for nodABC expression was isolated from plant exudate by constructing a nodABC-lacZ fusion to monitor the inducing activity. From ultraviolet-visible absorption spectra, proton nuclear magnetic resonance, and mass spectrometry, the inducer was determined to be 3',4', 5,7-tetrahydroxyflavone (luteolin). Luteolin is a normal secondary plant metabolite found throughout the plant kingdom that may serve to control nodABC expression during nodule development. This regulatory role for a flavone contrasts with the function of some flavonoids as defense compounds.

Flavonoids↗
PubMed1997

Glycosylated flavones as selective inhibitors of topoisomerase IV.

Three flavonoids which promoted Escherichia coli topoisomerase IV-dependent DNA cleavage were isolated from cottonseed flour and identified as quercetin 3-O-beta-D-glucose-[1,6]-O-alpha-L-rhamnose (rutin), quercetin 3-O-beta-D-galactose-[1,6]-O-alpha-L-rhamnose, and quercetin 3-O-beta-D-glucose (isoquercitrin). The most active one (rutin) also inhibited topoisomerase IV-dependent decatenation activity (50% inhibitory concentration, 64 microg/ml) and induced the SOS response of a permeable E. coli strain. Derivatives of quercetin glycosylated at position C-3 were shown to induce two site-specific DNA cleavages of pBR322 DNA, which were mapped by DNA sequence analysis to the gene encoding resistance to tetracycline. Cleavage at these sites was hardly detectable in cleavage reactions with quercetin or fluoroquinolones. None of the three flavonoids isolated from cottonseeds had any stimulatory activity on E. coli DNA gyrase-dependent or calf thymus topoisomerase II-dependent DNA cleavage, and they were therefore specific to topoisomerase IV. These results show that selective inhibitors of topoisomerase IV can be derived from the flavone structure. This is the first report on a DNA topoisomerase inhibitor specific for topoisomerase IV.

Base Sequence↗
PubMed1985

Modulation of rat hepatic aryl hydrocarbon hydroxylase by various flavones and polycyclic aromatic hydrocarbons.

The microsomal cytochrome P-450-dependent aryl hydrocarbon hydroxylase is important in the detoxification of polycyclic hydrocarbons as well as their activation to cytotoxic or carcinogenic derivatives. We have studied compounds that can modify the activity of this enzyme system. Three types of flavones are distinguished on the basis of their effect on the constitutive and polycyclic hydrocarbon-induced rat hepatic enzyme activity: (a) the 5,6- and 7,8-benzoflavones and their more hydrophobic derivatives inhibit the induced enzyme and increase or do not affect the constitutive enzyme activity; (b) derivatives typified by the 4'-hydroxylated benzoflavones similarly decrease both induced and constitutive activities; (c) polyhydroxyflavones inhibit the constitutive enzyme more than the induced enzyme. Two polycyclic hydrocarbons, 9-chloro-7H-dibenzo(a,g)carbazole and 6-aminochrysene, both potent inhibitors of the enzyme system, affect the constitutive and induced enzyme similar to compounds in groups a and b, respectively. The various activity-modulating compounds are useful reagents for distinguishing closely related enzymes present in a variety of different tissues and species under different conditions.

Animals↗
PubMedDate not supplied

Vasoacting agents flavone acetic acid and hydralazine given in combination enhance antitumor effects under condition of hyperthermia.

The combined effects of flavone acetic acid (FAA), hydralazine (HYD) and hyperthermia on B16 melanoma cells and solid tumor were examined in vitro and in vivo. In vitro, hyperthermia did not enhance the cytotoxicity of the combined use of FAA and HYD. In vivo, growth inhibition of B16 melanoma solid tumor by FAA (150 mg/kg) combined with HYD (5.0 mg/kg) could not be differentiated from that by FAA or HYD alone. Increased antitumor effect was recognized when FAA combined with HYD was used under conditions of hyperthermia. FAA combined with HYD significantly reduced tumor blood flow compared to FAA alone or HYD alone. We thus conclude that the significant reduction in tumor blood flow may play an important role in the enhanced antitumor effects of the combined treatment with FAA, HYD, and hyperthermia.

Animals↗