Showing papers on "Galangin published in 2003"
TL;DR: The data suggest that dietary phytochemicals exhibit substantial cell context-dependent AhR agonist as well as antagonist activities, and because phytochemistryicals and other AhR-active compounds in food are present in the diet at relatively high concentrations, risk assessment of dietary toxic equivalents of TCDD and related compounds should also take into account AhRagonists.
Abstract: Chemoprotective phytochemicals exhibit multiple activities and interact with several cellular receptors, including the aryl hydrocarbon (Ah) receptor (AhR). In this study we investigated the AhR agonist/antagonist activities of the following flavonoids: chrysin, phloretin, kaempferol, galangin, naringenin, genistein, quercetin, myricetin, luteolin, baicalein, daidzein, apigenin, and diosmin. We also investigated the AhR-dependent activities of cantharidin and emodin (in herbal extracts) in Ah-responsive MCF-7 human breast cells, HepG2 human liver cancer cells, and mouse Hepa-1 cells transiently or stably transfected with plasmids expressing a luciferase reporter gene linked to multiple copies of a consensus dioxin-responsive element. The AhR agonist activities of the compounds (1 and 10 micro M) were as high as 25% of the maximal response induced by 5 nM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and their potencies were dependent on cell context. Galangin, genistein, daidzein, and diosmin were active only in Hepa-1 cells, and cantharidin induced activity only in human HepG2 and MCF-7 cells. Western blot analysis confirmed that baicalein and emodin also induced CYP1A1 protein in the human cancer cell lines. The AhR antagonist activities of four compounds inactive as agonists in MCF-7 and HepG2 cells (kaempferol, quercetin, myricetin, and luteolin) were also investigated. Luteolin was an AhR antagonist in both cell lines, and the inhibitory effects of the other compound were dependent on cell context. These data suggest that dietary phytochemicals exhibit substantial cell context-dependent AhR agonist as well as antagonist activities. Moreover, because phytochemicals and other AhR-active compounds in food are present in the diet at relatively high concentrations, risk assessment of dietary toxic equivalents of TCDD and related compounds should also take into account AhR agonist/antagonist activities of phytochemicals.
312 citations
TL;DR: The results show that flavonoids can lead to reversible inhibition of the enzyme, and it is shown that the flavonols are competitive inhibitors, whereas luteolin is an uncompetitive inhibitor.
Abstract: Mushroom tyrosinase (EC 1.14.18.1) is a copper containing oxidase that catalyzes both the hydroxylation of tyrosine into o-diphenols and the oxidation of o-diphenols into o-quinones, and then forms brown or black pigments. In the present study, the effects of some flavonoids on the oxidation of L-3,4-dihydroxyphenylalanine (L-DOPA) have been studied. The results show that flavonoids can lead to reversible inhibition of the enzyme. A kinetic analysis showed that the flavonols are competitive inhibitors, whereas luteolin is an uncompetitive inhibitor. The rank order of inhibition was: quercetin > galangin > morin; fisetin > 3,7,4"-trihydroxyflavone; luteolin > apigenin > chrysin.
152 citations
TL;DR: In this paper, the authors evaluated the applicability of the Trolox Equivalent Antioxidant Capacity (TEAC) assay to predict the antioxidant effectivity of a compound.
134 citations
TL;DR: Activity of the flavonoids apigenin, baicalin and galangin against sensitive and antibiotic resistant strains of Staphylococculs aureus, Enterococcus faecalis, E. faecium, Escherichia coli and Pseudomonas aeruginosa was investigated.
104 citations
TL;DR: It was shown that preincubation of cells with flavonoids can influence cisplatin-induced apoptosis in different way, and combined treatment with QU and cis-Pt showed synergistic effect, however, GA combined with cis- Pt exhibited antagonism on cytotoxicity in L1210 murine leukemia cells.
73 citations
TL;DR: This study was designed to investigate the effect of five flavone derivatives variously substituted with hydroxyl groups on interleukin‐1β (IL‐1 β) gene expression in stimulated RAW 264.7 macrophages.
Abstract: It is known that the redox status of cells affects gene expression. Flavones, as natural antioxidants, efficiently modulate this status and may play a role in the regulation of inducible gene expression of inflammatory mediators. This study was designed to investigate the effect of five flavone derivatives variously substituted with hydroxyl groups (chrysin, galangin, kaempferol, quercetin and myricetin) on interleukin-1beta (IL-1beta) gene expression in stimulated RAW 264.7 macrophages. The cells were incubated with tested hydroxyflavones and stimulated with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma). Then, the following were estimated: the level of IL-1beta mRNA in these cells and the concentration of IL-1beta protein in cell-culture supernatants and cell lysates. Each of the tested compounds significantly decreased IL-1beta mRNA expression. The most potent inhibitor was chrysin (hydroxyflavone with two hydroxyl groups and a weak antioxidant activity). The effects of galangin and kaempferol were similar. Myricetin (hydroxyflavone with a strong antioxidant activity) significantly decreased the level of IL-1beta mRNA, but it had no effect on the IL-1beta protein synthesis. The results indicated that hydroxyflavones could modulate the IL-1beta gene expression in activated RAW 264.7 macrophages via inhibiting gene transcription. This action seems unlikely to be the result of antioxidant properties of tested compounds.
69 citations
Journal Article•
TL;DR: Results of HPLC analyses suggest that propolis samples collected from various parts of Croatia do not differ markedly in contents of chrysin, pinocembrin, naringenin and galangin but differ in the concentration of caffeic acid.
Abstract: Thin-layer chromatography of ethanolic extract of propolis (EEP) from the continental and Adriatic regions of Croatia showed that 72.2% of propolis samples contain galangin, 88.8% of samples contain kaempferol, naringenin and apigenin and 66.6% of samples contain caffeic acid. Caffeic acid, pinocembrin, galangin, chrysin and naringenin were analyzed by HPLC. In all samples, pinocembrin was the dominant flavonoid. In samples from the Adriatic region, concentration of pinocembrin ranged from 0.03 to 6.14% (x = 2.87%) and in the continental region samples from 0 to 4.74% (x = 2.84%). Chrysin was found in all propolis samples in a concentration ranging from 0.22 to 5.32% (x = 1.86%) in the continental region samples and from 0.03 to 3.64% (x = 1.96%) in samples from the Adriatic region. Chrysin was followed by naringenin, ranging from 0 to 1.14% (x = 0.42%) in samples from the Adriatic region and from 0.22 to 2.41% (x = 0.60%) in the continental region samples. Concentration of caffeic acid ranged from 0 to 10.11% (x = 2.69%) in the Adriatic region samples and from 0.27 to 2.67% (x = 1.37%) in samples from the continental region of Croatia. Results of HPLC analyses suggest that propolis samples collected from various parts of Croatia do not differ markedly in contents of chrysin, pinocembrin, naringenin and galangin but differ in the concentration of caffeic acid. All EEPs significantly inhibited the growth of Bacillus subtilis in comparison with the control (80% ethanol) (p < 0.05), showing inhibition zones of 16 +/- 2 mm for samples from the continental region, and of 18 +/- 3 mm for samples from the Adriatic region. There was no significant difference in antimicrobial activity of EEPs from the continental and Adriatic regions of Croatia, suggesting that bactericidal activity depends on synergism of all phenolic compounds.
54 citations
TL;DR: It is shown in the present paper that flavonoids possessing catalytic topo II inhibitory activity, strongly antagonize the clastogenicity of genistein in Chinese hamster V79 cells.
50 citations
TL;DR: It is concluded that the galangin inhibits excitatory transmission of the rat vas deferens with a mechanism involving, at least in part, vanilloid receptors.
32 citations
TL;DR: Analysis of the kinetic results led to the conclusion that the inhibitory mechanism of GE is totally different from that of some other previously reported inhibitors of FAS, such as cerulenin, EGCG (epigallocatechin gallate) and C75.
Abstract: The galangal (the rhizome of Alpinia officinarum, Hance) is popular in Asia as a traditional herbal medicine. The present study reports that the galangal extract (GE) can potently inhibit fatty-acid synthase (FAS, E.C.2.3.1.85). The inhibition consists of both reversible inhibition with an IC50 value of 1.73 μg dried GE/ml, and biphasic slow-binding inactivation. Subsequently the reversible inhibition and slow-binding inactivation to FAS were further studied. The inhibition of FAS by galangin, quercetin and kaempferol, which are the main flavonoids existing in the galangal, showed that quercetin and kaempferol had potent reversible inhibitory activity, but all three flavonoids had no obvious slow-binding inactivation. Analysis of the kinetic results led to the conclusion that the inhibitory mechanism of GE is totally different from that of some other previously reported inhibitors of FAS, such as cerulenin, EGCG (epigallocatechin gallate) and C75.
27 citations
TL;DR: It is proved that QU and LU positively modulated efficacy of cisplatin due to increasing of cisPlatin-induced apoptotic cell death and all tested flavonoids decreased doxorubicin cytotoxicity and caused cells to shift from G2/M to S phase of the cell cycle.
01 Jan 2003
TL;DR: Antimicrobial-activity-guided assay, that allows localization of bactericidal constituents in PEE, showed that flavonoid galangin (3, 5, 7-trihydroxyflavone) is compound with the strongest antimicrobial activity.
Abstract: Many plant-derived substances have antimicrobial activity and plants present good models for searching novel antimicrobials, especially against multi-resistant bacteria. Propolis is resinous substance collected by honeybees from various trees and possesses many biological activities. Spectrum of antimicrobial activity of propolis ethanolic extracts (PEE) is wide: bacteria, yeasts and dermatophytes. Substances with antimicrobial activity in propolis are: flavonoids (galangin, pinocembrin), esters of caffeic acid and essential oil components. In this research we have tested 3 samples of propolis collected from Croatia against clinical isolates of resistant bacteria: MRSA (n=10), multiple-resistant Enterococcus spp. (n=17) and Pseudomonas aeruginosa (n=10). Clinical isolates of MSSA and Salmonella spp. are also tested. In diffusion assay, all samples of PEE exhibited activity against Staphylococcus aureus strains with inhibition zones max. 20.6 mmp 2.5 (meanp SD) ; Enterococcus spp. strains and P. aeruginosa strains max. 15 mmp 1.9. PEE have no activity on Salmonella spp. In macrobroth two-fold dilution assay MIC’ s values exhibited range from 1.06 to 4.98 mg/mL for MRSA strains ; 2.33 to 9.09 mg/mL for Enterococcus spp. strains and 7.63 to 14.16 mg/mL for P. aeruginosa strains. Results show differences in antimicrobial activity among three PEEs which depends on concentration of antimicrobial compounds. Antimicrobial-activity-guided assay (bioassay in situ on developed TLC plates with Bacillus subtilis NCTC 8236 or “ autoantibiogram” ), that allows localization of bactericidal constituents in PEE, showed that flavonoid galangin (3, 5, 7-trihydroxyflavone) is compound with the strongest antimicrobial activity.
Patent•
14 Nov 2003
TL;DR: In this article, a method for the maintenance of bone health and/or the treatment, alleviation and prevention of bone disorder was proposed, which consisted of the administration to a mammal of an effective amount of galangin, a pharmaceutically acceptable salt of Galangin or a precursor of Galgin in an amount equivalent to between 0.5 and 100 mg per kg body weight per day.
Abstract: The present invention relates to a method for the maintenance of bone health and/or the
treatment, alleviation and/or prevention of bone disorder, said method comprising the
administration to a mammal of an effective amount of galangin, a pharmaceutically
acceptable salt of galangin or a precursor of galangin in an amount equivalent to between
0.5 and 100 mg galangin per kg body weight per day.