Showing papers on "Galangin published in 2006"

Flavonoids protect human retinal pigment epithelial cells from oxidative-stress-induced death.

Abstract: PURPOSE. To determine whether specific dietary and synthetic flavonoids can protect human retinal pigment epithelial (RPE) cells from oxidative-stress-induced death. METHODS. The efficacy and potency were determined of a variety of dietary and synthetic flavonoids on the survival of human ARPE-19 cells and primary human RPE cells treated with either hydrogen peroxide (H 2 O 2 ) or t-butyl hydroperoxide (t-BOOH). We determined the effective concentrations (EC 50 s) and the toxicities (LD 50 s) of the flavonoids after 24 hours, by using the MTT assay. The efficacy of vitamins E and C on RPE cell survival were compared under identical conditions. The ability of specific flavonoids to protect RPE cells from cell death was determined at various time intervals after the cells were exposed to oxidative stress. The ability of flavonoids to block the accumulation of intracellular reactive oxygen species was examined with dichlorofluorescein (DCF) fluorescence. Finally, the ability of flavonoids to induce phase-2 detoxifying enzymes was tested by immunoblot analysis for the transcription factor Nrf2 and the phase-2 gene product heme-oxygenase 1. RESULTS. Specific flavonoids protected human RPE cells from oxidative-stress-induced death with efficacies between 80% and 100% and potencies in the high-nanomolar and low-micromolar range. The toxicities of most of the effective flavonoids were low. The effective flavonoids included the dietary flavonoids fisetin, luteolin, quercetin, eriodictyol, baicalein, galangin and EGCG, and the synthetic flavonoids, 3,6-dihydroxy flavonol and 3,7 dihydroxy flavonol. Several flavonoids can protect RPE cells even when they are added after the cells have been exposed to oxidative stress. The flavonoids acted through an intracellular route to block the accumulation of reactive oxygen species. Many of these flavonoids induced the expression of Nrf2 and the phase-2 gene product heme-oxygenase 1 in human RPE cells. CONCLUSIONS. The results identify a select group of flavonoids that protect RPE cells from oxidative-stress-induced death with a high degree of potency and low toxicity. Many of these flavonoids also induce the expression of phase-2 detoxification proteins which could function to provide additional protection against oxidative stress. This select group of flavonoids and the foods that contain high levels of these compounds may have some clinical benefit for patients with retinal diseases associated with oxidative stress.

Chemical structure of flavonols in relation to modulation of angiogenesis and immune-endothelial cell adhesion.

Abstract: The antioxidant activity of flavonoids has been suggested to contribute to several health benefits associated with the consumption of fruits and vegetables. Four flavonols - myricetin (M), quercetin (Q), kaempferol (K) and galangin (G), all with different numbers of hydroxyl moieties (-OH) - were examined for their antioxidant activity and cytotoxicity on human umbilical vein endothelial cells (HUVECs) and for their potential antiangiogenic and cell adhesion effects. The relative antioxidant capacity of these flavonols in cell culture medium (cell-free system) and their intracellular antioxidant activity were M = Q > K = G, which correlated respectively with the presence of 3, 2, 1 and 0 moieties of -OH on their B-ring. The higher the numbers of -OH moieties on the B-ring the less toxic the flavonol was to HUVEC, and the LD50 was determined as: M (100 microM) > Q (50 microM) > K (20 microM) > G (10 microM). These flavonols at approximately 0.5 LD50 doses suppressed the vascular endothelial growth factor (VEGF)-stimulated HUVEC tubular structure formation by: M (47%) > Q (37%) > K (15%) > G (14%), which was not linearly associated with their numbers of -OH moieties. However, the magnitude of flavonols' suppression of activated U937 monocytic cells adhesion to HUVEC was associated with the number of -OH moieties on the B-ring. This was prominent when U937 cells were pretreated with these flavonols. In contrast, the numbers of -OH moiety had no apparent influence on the adhesion or expression of adhesion molecules when activated HUVECs were pretreated with these flavonols. The presence of different numbers of -OH moieties on the B-ring of the flavonols may contribute to their antioxidant activity as well as their toxicity and may play an important role in their potency for biological action such as angiogenesis and immune-endothelial cell adhesion, which, respectively, are important processes in the development of cancer and atherosclerosis.

Propolis from the northwest of Argentina as a source of antifungal principles

Abstract: Aims: To determine the antimycotic and cytotoxic activities of partially purified propolis extract on yeasts, xylophagous and phytopathogenic fungi. To compare these activities with pinocembrin and galangin isolated from this propolis and with the synthetic drugs ketoconazole and clortrimazole. Methods and Results: Ethanolic propolis extract was partially purified by cooling at −20°C. Two of its components were isolated by HPLC and identified as pinocembrin and galangin. The antifungal activity was assayed by bioautography, hyphal radial growth, hyphal extent and microdilution in liquid medium. Cytotoxicity was studied with the lethality assay of Artemia salina. The obtained results were compared with the actions of ketoconazole and clortrimazole. The results showed that the antifungal potency of ketoconazole and clortrimazole is higher than pinocembrin, galangin and the partially purified propolis extract in this order. Otherwise, the cytotoxicity of the synthetic drugs is also the highest. Conclusions: Partially purified propolis extract inhibits fungal growth. The comparison of its relative biocide potency and cytotoxicity with synthetic drugs and two components of this propolis (pinocembrin and galangin) showed that the propolis from ‘El Siambon’, Tucuman, Argentina, is a suitable source of antifungal products. Significance and Impact of the Study: The partially purified propolis extract and its isolated compounds, pinocembrin and galangin, have the capacity of being used as antifungals without detriment to the equilibrium of agroecosystems. The impact of this study is that the preparation of agrochemicals with reduced economic costs using a partially purified preparation as the active principle is possible.

Methylation protects dietary flavonoids from rapid hepatic metabolism.

Abstract: The metabolic stability of two potential cancer chemopreventive flavones, i.e. 5,7-dimethoxyflavone (5,7-DMF) and 3',4'-dimethoxyflavone (3',4'-DMF), compared with the non-methylated flavone galangin (3,5,7-trihydroxyflavone), was investigated in human hepatic preparations. Galangin, as expected, was extensively metabolized mainly by glucuronidation in human liver S9 fractions in the presence of appropriate co-factors. In contrast, 5,7-DMF and 3',4'-DMF were metabolically highly stable with only a small fraction of 3',4'-DMF undergoing oxidation. Consistent with the S9 fraction results, galangin was almost completely depleted after 2-h incubations in freshly plated hepatocytes. The hepatocytes also showed some metabolism of 3',4'-DMF, but virtually none of 5,7-DMF. In human liver microsomes, 5,7-DMF was more metabolically stable than 3',4'-DMF. The observations present a new strategy for examining the metabolic stability of dietary flavonoids and suggest that methylated flavonoids may have a high oral bioavailability compared with their non-methylated forms, which will make them more likely to be useful as cancer chemoprotectants.

Growth of a human mammary tumor cell line is blocked by galangin, a naturally occurring bioflavonoid, and is accompanied by down-regulation of cyclins D3, E, and A

Abstract: Introduction This study was designed to determine if and how a non-toxic, naturally occurring bioflavonoid, galangin, affects proliferation of human mammary tumor cells. Our previous studies demonstrated that, in other cell types, galangin is a potent inhibitor of the aryl hydrocarbon receptor (AhR), an environmental carcinogen-responsive transcription factor implicated in mammary tumor initiation and growth control. Because some current breast cancer therapeutics are ineffective in estrogen receptor (ER) negative tumors and since the AhR may be involved in breast cancer proliferation, the effects of galangin on the proliferation of an ER-, AhRhigh line, Hs578T, were studied.

TCDD-induced CYP1A1 expression, an index of dioxin toxicity, is suppressed by flavonoids permeating the human intestinal Caco-2 cell monolayers.

Abstract: Since the toxicological effects of dioxins are mainly mediated by the aryl hydrocarbon receptor (AhR), an in vitro assessment system for AhR activity was used in this study to search for flavonoids that attenuated dioxin toxicity through the intestinal epithelial monolayer. When AhR transformation in Hepa-1c1c7 cells was examined by southwestern ELISA, nine flavonoids among 34 kinds of flavonoids inhibited the transformation by more than one-half. When each flavonoid with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was added to dioxin-responsive HepG2 cells, seven flavonoids significantly restrained the TCDD-induced transcriptional activity of the CYP1A1 promoter. Furthermore, those seven flavonoids that had permeated the Caco-2 cell monolayers demonstrated an inhibitory effect on both the AhR transformation and on the transcriptional activity of the CYP1A1 promoter. The expression level of the CYP1A1 mRNA and protein induced by TCDD was suppressed by flavone, galangin, and tangeretin. It is proposed from these results that some flavonoids have the ability to suppress dioxin-induced AhR activity after permeating the human intestinal epithelial cell monolayer.

Use of the pig caecum model to mimic the human intestinal metabolism of hispidulin and related compounds.

Abstract: Up to now, the metabolism of hispidulin (5,7,4'-trihydroxy-6-methoxyflavone), a potent ligand of the central human benzodiazepine receptor, has not been investigated. To elucidate the metabolism of hispidulin in the large intestine, its biotransformation by the pig caecal microflora was studied. In addition, the efficiency of the pig caecal microflora to degrade galangin (3,5,7-trihydroxyflavone), kaempferol (3,5,7,4'-tetrahydroxyflavone), apigenin (5,7,4'-trihydroxyflavone), and luteolin (5,7,3',4'-tetrahydroxyflavone) was investigated. Identification of the formed metabolites was performed by high-performance liquid chromatography (HPLC)-diode array detection, HPLC-electrospray ionization-tandem mass spectrometry, and high-resolution gas chromatography-mass spectrometry. The caecal microflora transformed hispidulin to scutellarein (5,6,7,4'-tetrahydroxyflavone), an effective alpha-glucosidase inhibitor, and 3-(4-hydroxyphenyl)-propionic acid; galangin to phenylacetic acid and phloroglucinol; kaempferol to 4-hydroxyphenylacetic acid, phloroglucinol, and 4-methylphenol; apigenin to 3-(4-hydroxyphenyl)-propionic acid and 3-phenylpropionic acid, and luteolin to 3-(3-hydroxyphenyl)-propionic acid, respectively. To elucidate to what extent different hydroxylation patterns on the B-ring influence the degradation degree of flavonoids, the conversions of galangin and kaempferol as well as that of apigenin and luteolin were compared with those of quercetin (3,5,7,3',4'-pentahydroxyflavone) and chrysin (5,7-dihydroxyflavone), respectively. Regardless of the flavonoid subclass, the presence of a hydroxy group at the 4'-position seems to be a prerequisite for fast breakdown. An additional hydroxy group at the B-ring did not affect the degradation degree.

Susceptibility of oral pathogenic bacteria and fungi to brazilian green propolis extract

Abstract: The aim of this study was to investigate the antimicrobial activity of ethanolic extract and fractions of Brazilian green propolis (BGP) collected by bees from Baccharis dracunculifolia against 16 oral pathogenic microorganisms. BGP was examinated by Reversed-Phase High-Performance Liquid Chromatography (RPHPLC) and its absorption spectra was assessed using UV-Spectrophotometer. Identification of flavonoids and other chemical constituents were carried out using authentic standards. Antimicrobial activity was evaluated by agar diffusion and dilution method. The results indicate that all microorganisms tested were susceptible to BGP. None of the essayed fractions (Coumaric acid, Kaempferol, Pinobanskin-3-acetate, Chrysin, Galangin, Kaempferide, and Artepillin C) was more active than the extract, suggesting a synergistic effect of propolis constituents for the antimicrobial activity.

Methylation protects dietary flavonoids from rapid hepatic metabolism

Abstract: The metabolic stability of two potential cancer chemopreventive flavones, ie 5,7-dimethoxyflavone (5,7-DMF) and 3',4'-dimethoxyflavone (3',4'-DMF), compared with the non-methylated flavone galangin (3,5,7-trihydroxyflavone), was investigated in human hepatic preparations Galangin, as expected, was extensively metabolized mainly by glucuronidation in human liver S9 fractions in the presence of appropriate co-factors In contrast, 5,7-DMF and 3',4'-DMF were metabolically highly stable with only a small fraction of 3',4'-DMF undergoing oxidation Consistent with the S9 fraction results, galangin was almost completely depleted after 2-h incubations in freshly plated hepatocytes The hepatocytes also showed some metabolism of 3',4'-DMF, but virtually none of 5,7-DMF In human liver microsomes, 5,7-DMF was more metabolically stable than 3',4'-DMF The observations present a new strategy for examining the metabolic stability of dietary flavonoids and suggest that methylated flavonoids may have a high oral bioavailability compared with their non-methylated forms, which will make them more likely to be useful as cancer chemoprotectants

Medicine containing galangin and preparation method thereof

Abstract: The invention relates to a medicine that contains galangal rhizome and relative preparation, wherein the galangal rhizome chromocor separated from the root of galangal rhizome contains chromocor at 50-99.8% and galangal rhizome at 30-80%. The preparation comprises: (1) extracting, abstracting, inverted abstracting, depositing chromocor, and purifying the galangal rhizome to obtain the galangal rhizome chromocor, to be used to prepare oral or ejection agent. The invention has simple process and easy operation, while the product has high purity. And the inventive medicine can be used to resist oxidization, etc.

Expression promoter for active oxygen eliminating enzyme

Abstract: PROBLEM TO BE SOLVED: To provide an expression promoter for active oxygen eliminating enzyme suppressing excessive active oxygen in the body. SOLUTION: The invention relates to the expression promoter for active oxygen eliminating enzyme comprising at least one of galangin or phloretin. The invention also relates to the expression promoter for active oxygen eliminating enzyme in which the enzyme eliminating active oxygen is SOD (superoxide dismutase). COPYRIGHT: (C)2008,JPO&INPIT