SEARCH · Search PubMed
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.
A flavones has been isolated from the roots of Polygala stenopetala. The structure was established on the basis of UV, Mass spectrum, 1HNMR, 13CHMR and NOE difference experiments as 5,7,4-trihydroxy-3, 5-dimethoxyflavone (tricin) This is for the first time that a flavones has been isolated from the species belonging to the family Polygalaceae.
This paper reports the study on the stability of total flavones in guanshu tablet by heating and accelerating method. Taking the total flavone contents of the tablet as the index, the time of validity of guanshu tablet at room temperature 25 degrees C is calculated to be 9.6 years by chemical kinetic analysis.
Flavone acetic acid represents a novel chemical structure currently undergoing clinical investigation. Broad spectrum activity has been observed in preclinical animal screens, but at doses close to toxic in mice. Phase I clinical trials have established that equivalent plasma drug levels can be achieved in humans, but to date Phase II trials have not demonstrated significant activity in a range of tumor types. Little is known about the drug's biotransformation, although metabolites have been implicated in proposed mechanisms of action. In this paper, we have purified the two major human metabolites present in urine (also the only two metabolites detected in plasma) and characterized their structure, chemical properties, activity, and pharmacokinetics. Metabolite 1 (M1) was a glucuronide conjugated to the 8-acetic acid grouping (Mr 456), was chemically labile, and showed a strong tendency to undergo chemical rearrangement at mildly alkaline pH. Metabolite 2 (M2) was also a glucuronide (Mr 456) but appeared to be an unusual isomer of M1. Both were noncytotoxic. In patients, biotransformation represented the predominant mechanism of drug clearance with as much as 80% of a low dose (0.5 g/m2) recovered in urine as M1 and M2 after only 6 h. At high dose (4.8 to 8.6 g/m2, 1- to 6-h infusion) the appearance of peak concentrations of metabolites in plasma and urine was delayed, apparently due to saturation of glucuronidation pathways. This resulted in an overall reduction in drug clearance by 3- to 4-fold. Mice cleared flavone acetic acid much more slowly than patients (289 ml/h/m2 after 600 mg/m2 i.p. versus 2.3 liters/h/m2 after 4.8 g/m2-1-h i.v. infusion) without producing M1 or M2. A different metabolite, exhibiting characteristics of a conjugate, was detected at low concentrations in plasma, tissues, and tumor. Extensive metabolism to inactive products followed by their rapid clearance may contribute to the lack of activity so far seen in humans.
Flavone acetic acid is the second in a series of compounds based on the flavonoid aglycone ring structure to be clinically evaluated in malignant disease. Preclinical studies have indicated that a minimum plasma level of 150 micrograms/ml is required before therapeutic efficacy (in a wide range of experimental tumors) is seen in mice; both in vitro and in vivo studies also suggest that the duration of drug exposure is crucial in determining activity. Thus a Phase I trial has been performed in a total of 54 patients using 3 schedules, i.e., a 1-, 3-, and 6-h infusion. In each case, treatment was given once weekly for a minimum of 3 weeks. The maximum tolerated doses were 6.4, 6.4, and 10.0 g/m2, respectively. Dose limiting toxicity was denoted by an intense feeling of warmth and flushing with a 1-h infusion, hypotension with a 3-h infusion, and hypotension and diarrhea with a 6-h infusion. No objective responses were seen in this Phase I trial. The recommended doses for Phase II trials of flavone acetic acid in Europe are 4.8 g/m2 over 1 h or 8.6 g/m2 over 6 h. At these doses the peak plasma concentrations obtained are 650 and 388 micrograms/ml, respectively. Total drug exposure (assessed by an area under the curve greater than 100 micrograms/ml) was approximately 50% greater for the 6-h schedule. This Phase I trial indicates that peak plasma concentrations associated with experimental activity are achievable in humans, although optimal drug exposure times have not yet been defined.
We have conducted a Phase I and initial clinical pharmacological evaluation of LM985, the first of a series of compounds based on the flavone ring structure to be considered for clinical trial in malignant disease. The drug was administered i.v. to 26 patients with advanced cancer on an every-21-day schedule. Patients were treated at 14 dosage levels ranging from 10 to 1500 mg/m2. Dose limiting toxicity was identified as acute reversible hypotension occurring during drug infusion; no leukopenia, alopecia, hepatic toxicity, or renal toxicity was observed, but at the higher dose range, mild sedation was apparent. Twenty patients had measurable disease and were evaluable for response. One patient with colorectal carcinoma had stable disease after three courses of LM985; however, no other responses were seen. Pharmacokinetic and in vitro drug degradation studies imply that the ester LM985 is hydrolyzed to LM975 (flavone acetic acid) rapidly in vivo. LM975 is active in a variety of animal tumor models, but it does not have the cardiovascular side effects seen with LM985 (hypotension and bradycardia) in pithed or anesthetized rats. We would recommend that LM975 be considered for clinical trial, because it seems likely that substantially higher doses of LM975 than of LM985 can be given without dose limiting cardiovascular toxicity.
Flavone acetic acid is a novel structure which exhibits an interesting spectrum of antitumor activity in preclinical studies. It has little antitumor activity in the leukemias and pronounced antitumor activity in solid tumors. Preclinical therapeutic, toxicologic, and pharmacokinetic studies are summarized and considered together to introduce the concept of a therapeutic window of effective plasma concentrations and effective exposure times in attempts to maximize therapeutic effects and minimize toxic effects. Plasma concentrations, predicted to fall from 600 to 100 micrograms/ml over 10 hours resulting from 267 mg/kg ip bolus injections in mice are curative to sc implanted colon 38. Doses of 356 mg/kg and higher cause acute lethality in many mice. Iv doses cause acute lethality in mice more frequently than ip doses, which suggests a peak toxic effect. However, iv infusions in mice, which also can be curative to colon 38, can also result in a lethal effect, although more delayed, even though the predicted plasma concentrations are much below the peak plasma concentrations that appear to be necessary for acute lethality. Plasma concentrations, 100 to 600 micrograms/ml predicted to result from single doses that are therapeutic and not acutely lethal in mice, if maintained by infusion in dogs for 28 hours or longer result in delayed lethality. We conclude that relatively high plasma concentrations (greater than 100 micrograms/ml) are needed for therapeutic activity with this antitumor agent and that lethality can result from two distinctly different causes. An acute lethality can result from an excessively high peak plasma concentration (greater than 600 micrograms/ml). A delayed lethality can result from a too-long exposure (greater than 24 hrs) at therapeutically effective plasma concentrations (100-600 micrograms/ml). We also note that unexpected kinetic differences exist among the mouse, dog, and man. Whereas usually with antitumor agents plasma clearances are proportional to body surface area, and hence faster in small species, quite the opposite is true with flavone acetic acid. Mice exhibit a slower plasma clearance relative to dogs and man.
For naturally occurring flavones, quercetin, fisetin, nobiletin, and tangeritin, protect cultured rat liver epithelial-like cells against aflatoxin B1-induced cytotoxicity and inhibit the binding of [3H] aflatoxin B1 to cellular DNA. The methoxy-substituted flavones, nobiletin and tangeritin, show greater protection against cytotoxicity than do the hydroxy-substituted compounds, quercetin and fisetin.
The antitumour activity of a combination of Mitomycin C (MMC), a prototypical bioreductive agent, with the vascular occluding agent, flavone acetic acid (FAA), was examined in a murine tumour. Flavone acetic acid induced a long lived reduction of blood flow in the tumour thereby inducing hypoxia and cell death by ischaemia. Dose response curves for tumour cell survival and regrowth delay were constructed after each agent administered alone or when combined. The greatest antitumour effect was measured when the two agents were administered simultaneously. The reduced tumour perfusion induced by the combination was not lower than that for FAA alone indicating that the greater in vivo effect was not due to enhancement of the vascular occluding effect of the FAA. The role of the tumour microenvironment in determining the MMC cytotoxicity was examined using in vitro incubations of MMC under controlled oxygenation and pH. MMC cytotoxicity was increased in hypoxia (enhancement ratio = 2.0) and also when extracellular pH was reduced from 7.4 to 6.4 (enhancement ratio = 1.5). Since the microenvironmental consequences of induced ischaemia are reductions in both oxygenation and pH these parameters are probably responsible in large part for the enhancement of cytotoxicity observed when MMC and FAA are combined.
Molecular electrostatic potential (MEP) maps of certain 3-methoxy flavone derivatives having different anti-picornavirus activities have been studied. Geometries of the molecules were optimised and charge distributions computed using the AM1 molecular orbital method. Hybridization displacement charges (HDC) were combined with the Löwdin charge distributions to compute the MEP maps. Reliability of the method of computing MEP maps was tested by studying certain other molecules for which ab initio MEP results are available. The anti-picornavirus activities of the flavones have been shown to be related with negative MEP values in two regions, one near the 3-methoxy group and another in a diagonally opposite region near the substituent attached to the C7 atom of the molecules.
Flavone acetic acid, an agent which has been implicated in both tumor vasculature collapse and NK cell activations, has been tested recently as a potential anti-cancer chemotherapeutic agent. We have tested this agent in combination with adoptive immunotherapy using IL-2 activated natural killer (A-NK) cells in a metastatic B16 melanoma model in C57BL/6 mice. By using rhodamine-labeled A-NK cells we have been able to quantitate both the number of A-NK cells that localize within each tumor section and the percentage of the tumor area occupied by A-NK cells. This has been accomplished using an image analysis system. Flavone acetic acid (200 mg/kg, i.p.) given one day prior to the injection of A-NK cells increased the area of the tumor occupied by A-NK cells and the area of individual A-NK cells approximately 2-fold; however, it did not appear to increase the number of A-NK cells per tumor cross-section. Nevertheless, this increase did not lead to any significant change in the therapeutic efficacy of A-NK cell adoptive immunotherapy. Our studies therefore suggest that mere enhancement of A-NK cell recruitment into tumor metastases does not necessarily translate into enhanced metastatic therapeutic efficacy. Moreover, this method may be a useful tool for pre-screening of compounds which enhance the accumulation of adoptively transferred cells into tumor metastases prior to in vivo screening for therapeutic efficacy.
IMPORTANCE: No oral medication is currently approved for the management of urolithiasis. Guang Jing Qian Cao (Desmodium styracifolium total flavone capsules; hereinafter, Guang Jing), a traditional Chinese herbal extract, has shown clinical benefits for urolithiasis, but randomized clinical trials are needed to assess its effectiveness. OBJECTIVE: To evaluate whether Guang Jing improves stone passage rates (SPRs) compared with placebo in adults with urolithiasis. DESIGN, SETTING, AND PARTICIPANTS: This double-blind, placebo-controlled, phase 3 randomized clinical trial was conducted at 34 sites in China from December 2017 to April 2020. Participants included adults (aged 18-70 years) with diagnosed ureteral stones. Data analysis was conducted on November 4, 2020. INTERVENTION: Participants were randomized 3:1 to receive oral Guang Jing (0.6 g) or matching placebo 3 times daily for 28 days, in addition to investigator-prescribed background medication. MAIN OUTCOMES AND MEASURES: The primary outcome was SPR by day 28, confirmed by computed tomography. Secondary outcomes included SPR by day 14, stone migration rate, and stone migration distance. Between-group comparisons were performed using the Cochran-Mantel-Haenszel test for categorical outcomes and t tests for continuous outcomes. RESULTS: A total of 606 participants were randomly assigned to receive Guang Jing (n = 458) or placebo (n = 148). Their mean (SD) age was 43.0 (12.0) years, 474 (78.2%) were male, and the mean (SD) stone size was 0.6 (0.1) cm. The SPR by day 28 was significantly higher for the Guang Jing group compared with the placebo group (204 of 457 [44.6%] vs 50 of 148 [33.8%]; relative risk, 1.32 [95% CI, 1.03-1.69]; P = .03), with an absolute risk difference of 10.9 (95% CI, 2.0-19.7) percentage points. No significant between-group differences in SPR by day 14 (Guang Jing vs placebo: 133 [29.1%] vs 33 [22.3%]; P = .14) or stone migration distance (mean [SD], 29.5 [51.8] mm vs 29.7 [43.8] mm; P = .11) were observed. Adverse event rates were similar for the Guang Jing and placebo groups (88 [19.3%] vs 27 [18.2%]). CONCLUSIONS AND RELEVANCE: In this randomized clinical trial, treatment with Guang Jing significantly increased the expulsion of 5- to 10-mm ureteral stones by day 28, with a favorable safety profile. These findings suggest that Guang Jing may be an additional medical expulsive therapy option for appropriately selected patients. TRIAL REGISTRATION: Chinese Clinical Trial Registry Identifier: ChiCTR-IIR-17013275.
The concentrations of the polymethoxylated flavones (PMFs) in peels of selected citrus cultivars grown in Jamaica and Mexico were determined. The PMFs were extracted from sun-dried citrus peels with reagent-grade methanol. Analyses were carried out by reverse-phase HPLC and UV detection. The column used was a C(18) 5 microm (150 x 4.6 mm) Discovery column. Elution was in the gradient mode, using a ternary mobile phase. The results showed that all the citrus cultivars used contained at least three of the six major PMFs quantified. Ortanique peel contained the highest quantity of PMFs (34,393 +/- 272 ppm), followed by tangerine (28,389 +/- 343 ppm) and Mexican sweet orange (sample 1; 21,627 +/- 494 ppm). The major PMFs, i.e. sinensetin, nobiletin, tangeretin, heptamethoxyflavone, tetramethylscutellarein and hexamethyl-o-quercetagetin, present in the peels of 20 citrus cultivars, was quantified. The results were compared with those of Florida citrus peels. A large amount of citrus peels and byproducts are produced in the Caribbean which could provide a cheap and convenient source of PMFs.
Flavones mutagenic in Salmonella typhimurium fall into two distinct classes, characterized by different structural and metabolic activation requirements and by different strain responses. The mutagenic potencies of a prototype agent of each class, quercetin (3,3',4',5,7-hydroxyflavone) and norwogonin (5,7,8-hydroxyflavone), were determined in tester strains differing in excision-repair capability and in the presence or absence of plasmid pKM101. Two series of strains were used, one with the hisD3052 frameshift mutation and one with the hisG46 missense mutation. With both agents and for both series of strains, the mutagenic response was markedly dependent on the absence of excision repair and the presence of the pKM101 plasmid.
Two novel prenylated flavones, termed Cannflavin A and B, were isolated from the cannabinoid free ethanolic extract of Cannabis sativa L. Both compounds inhibited prostaglandin E2 production by human rheumatoid synovial cells in culture.
OBJECTIVE: To study the effects of total flavone of Abelmoschl Manihot L. Medic (TFA) on the function of platelets and to explore its mechanism. METHODS: Rat models of artery-veins bypassing thrombus formation were used. The platelets of rabbits were collected. Platelet aggregation was induced by collagen and intracellular calcium ion concentration ([Ca(2+)]i) was assayed by Fura-2 method. RESULTS: TFA (25, 50, 100 mg/kg) significantly and dose-dependently reduced the weight of thrombus. TFA (0.025, 0.05, 0.1 mg/ml) possessed dose-dependant inhibitory effects on rabbits' platelet aggregation induced by collagen. TFA significantly reduced the resting and CaCl(2)-induced increase of free intracellular calcium concentration ([Ca(2+)]i) in rabbit platelet in vitro. CONCLUSION: TFA has an antiplatelet effect via the inhibition on the influx of Ca(2+).
Spinoside, new coumaroyl flavone glycoside was isolated from the n-butanol fraction of the mathanolic extract of the whole plant of Amaranthus spinosus and assigned the structure 7-p-coumaroyl apigenin 4-O-beta-D-glucopyranoside (1) on the basis of spectroscopic techniques including 1D and 2D NMR spectroscopy. In addition alpha- xylofuranosyl uracil (2), beta-D-ribofuranosyl adenine (3) and beta-sitosterol glucoside (4) have also been isolated for the first time from this species.
The chloroform extract of the aerial part of Limnophila geoffrayi showed antimycobacterial and antioxidant activities. Bioassay-guided fractionation has led to the isolation of the flavones nevadensin (5,7-dihydroxy-6,8,4'-trimethoxyflavone, 1) and isothymusin (6,7-dimethoxy-5,8,4'-trihydroxyflavone, 2). Both compounds 1 and 2 exhibited inhibition activity against Mycobacterium tuberculosis, with equal MIC value of 200 microg/mL. Only compound 2 exhibited antioxidant activity against the radical scavenging ability of DPPH, with the IC50 value of 7.7 microg/mL. The crude hexane, chloroform and methanol extracts as well as the pure compounds 1 and 2 did not exhibit mutagenic activity in the Bacillus subtilis recassay.
Hispidulin, a natural flavone, and theophylline inhibited platelet aggregation triggered by adenosine-5'-monophosphate, arachidonic acid, paf-acether and collagen. Hispidulin was 100-fold more potent than theophylline. A threshold concentration of PGE1 did not modify the anti-aggregatory effect of hispidulin but potentiated the effect of theophylline. A threshold concentration of hispidulin had no effect on the inhibitory action of theophylline. Hispidulin (100 microM) and theophylline (10 mM) increased the control cAMP level in platelets 4-fold. A threshold concentration of PGE1 had a small effect on hispidulin-induced cAMP levels but increased the theophylline-induced cAMP levels 3-fold. Theophylline (10 mM)-induced cAMP levels were not modified by hispidulin. We demonstrate a correlation between the inhibition of platelet aggregation and the increase in cAMP levels induced by hispidulin. These data suggest that hispidulin could inhibit platelet aggregation by elevating cAMP levels by a mechanism different from that of theophylline or PGE1.