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Showing papers on "Flavanone published in 2007"


Journal ArticleDOI
TL;DR: Oral administration of the flavanone aglycones, hesperetin and naringenin, lead to their rapid absorption as their conjugated forms, and cumulative urinary recovery data indicated low bioavailability for both flavanones.
Abstract: Hesperetin and naringenin, the aglycones of the flavanone glycosides hesperidin and naringin, occur naturally in citrus fruits. They exert interesting pharmacological properties such as antioxidant, anti-inflammatory, blood lipid and cholesterol lowering and are considered to contribute to health benefits in humans. However, no information is available on the pharmacokinetics of the citrus flavanones hesperetin and naringenin after their oral administration to humans as pure aglycones. Therefore, the objective of the present investigation was the evaluation of the pharmacokinetic parameters of hesperetin and naringenin in plasma and urine, after their single oral administration in humans in the form of solid dispersion capsules, and also to improve the absorption rate of flavanones by using aglycones rather than the naturally occurring glycosides. Six healthy volunteers received orally 135 mg of each compound, hesperetin and naringenin, under fasting conditions. Blood samples were collected at 14 different time points over a 12 h period. Urine was collected over 24 h, in five sequential timed intervals. Plasma and urine hesperetin and naringenin concentrations, after enzymatic hydrolysis of their conjugated forms, were measured using validated high-pressure liquid chromatography methods. Pharmacokinetic parameters for hesperetin and naringenin, such as Cmax, Tmax, AUC0−t, AUC0−∞, CL/F, V/F, t1/2, MRT, Ae, Ae(0–24), and Rmax were calculated from their plasma or urine concentrations. Pharmacokinetic analysis showed that both hesperetin and naringenin were rapidly absorbed and their concentrations in plasma observed 20 min after dosing and reached a peak in 4.0 and 3.5 h, respectively. The mean peak plasma concentration (Cmax) for hesperetin and naringenin were 825.78±410.63 ng/ml (2731.8±1358.4 nmol/l) and 2009.51±770.82 ng/ml (7386.6±2833.4 nmol/l), respectively and the mean AUC0−∞ values were 4846.20±1675.99 ng h/ml and 9424.52±2960.52 ng h/ml for hesperetin and naringenin, respectively. The elimination half-life for hesperetin was found to be 3.05±0.91 h and for naringenin 2.31±0.40 h, respectively. The mean values of the relative cumulative urinary excretion, as percentage of the administered dose, for hesperetin and naringenin, were found to be 3.26±0.44 and 5.81±0.81%, respectively. Oral administration of the flavanone aglycones, hesperetin and naringenin, lead to their rapid absorption as their conjugated forms. The cumulative urinary recovery data indicated low bioavailability for both flavanone aglycones, owing to extensive first-pass metabolism partly by cleavage of the C-ring by the enzymes of intestinal bacteria leading to degradation products such as phenolic acids.

286 citations


Journal ArticleDOI
TL;DR: The metabolic engineering of central metabolic pathways described in the present work increased the production of pinocembrin, naringenin, and eriodictyol in 36 h up to 1,379%, 183%, and 373%, respectively, over production with the strains expressing only the flavonoid pathway.
Abstract: The identification of optimal genotypes that result in improved production of recombinant metabolites remains an engineering conundrum. In the present work, various strategies to reengineer central metabolism in Escherichia coli were explored for robust synthesis of flavanones, the common precursors of plant flavonoid secondary metabolites. Augmentation of the intracellular malonyl coenzyme A (malonyl-CoA) pool through the coordinated overexpression of four acetyl-CoA carboxylase (ACC) subunits from Photorhabdus luminescens (PlACC) under a constitutive promoter resulted in an increase in flavanone production up to 576%. Exploration of macromolecule complexes to optimize metabolic efficiency demonstrated that auxiliary expression of PlACC with biotin ligase from the same species (BirAPl) further elevated flavanone synthesis up to 1,166%. However, the coexpression of PlACC with Escherichia coli BirA (BirAEc) caused a marked decrease in flavanone production. Activity improvement was reconstituted with the coexpression of PlACC with a chimeric BirA consisting of the N terminus of BirAEc and the C terminus of BirAPl. In another approach, high levels of flavanone synthesis were achieved through the amplification of acetate assimilation pathways combined with the overexpression of ACC. Overall, the metabolic engineering of central metabolic pathways described in the present work increased the production of pinocembrin, naringenin, and eriodictyol in 36 h up to 1,379%, 183%, and 373%, respectively, over production with the strains expressing only the flavonoid pathway, which corresponded to 429 mg/liter, 119 mg/liter, and 52 mg/liter, respectively.

253 citations


Journal ArticleDOI
TL;DR: In this article, the authors developed a system for producing "unnatural" flavonoids and stilbenes in Escherichia coli, which included a substrate synthesis step for CoA esters synthesis from carboxylic acids by 4-coumarate:CoA ligase, a polyketide synthesis stage for conversion of the co-a esters into flavanones, and a modification step for modification of the flavanone by flavone synthase, flavone 3beta-hydroxylase and flavonol synthase.

204 citations


Journal ArticleDOI
TL;DR: Cytotoxic activities of some natural flavonoids identified in the medicinal plants were evaluated for the first time and none of these derivatives shown to have toxicity toward normal peripheral blood mononuclear cells, over the concentration range tested.

114 citations


Journal ArticleDOI
TL;DR: It is shown, for the first time, that naturally-occurring flavonoids inhibit M MP-1 and down-regulate MMP-1 expression via an inhibition of the AP-1 activation although the cellular inhibitory mechanisms differ depending on their chemical structures.
Abstract: Some plant flavonoids in the form of whole plant extracts have been used topically for skin inflammatory disorders. Since matrix metalloproteinase-1 (MMP-1, collagenase-1) plays an important role in unbalanced turn-over or rapid breakdown of collagen molecules in human inflamed/UV-irradiated skin, the effects of natural flavonoids on MMP-1 activity and MMP-1 expression were studied to establish the therapeutic potential. Against recombinant human MMP-1, flavonols such as quercetin and kaempferol were strong inhibitors with IC50 values of 39.6 and 43.7 microM, respectively, while flavones such as apigenin and wogonin showed only weak inhibitory activity. In addition, quercetin, kaempferol, apigenin and wogonin (12.5-25.0 microM) strongly inhibited MMP-1 induction in 12-O-tetradecanoylphorbol 13-acetate-treated human dermal fibroblasts, but naringenin (a flavanone) did not. By means of the electrophoretic mobility shift assay, these flavonoids were also found to inhibit activation of the transcription factor, activator protein-1 (AP-1). Moreover, quercetin inhibited extracellular signal-regulated protein kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) activation, and kaempferol inhibited p38 MAPK and c-Jun N-terminal kinase (JNK) activation among the MAPKs tested. In contrast, flavones and naringenin did not inhibit the activation of these three MAPKs. These results have shown, for the first time, that naturally-occurring flavonoids (quercetin, kaempferol, apigenin and wogonin) inhibit MMP-1 and down-regulate MMP-1 expression via an inhibition of the AP-1 activation although the cellular inhibitory mechanisms differ depending on their chemical structures. Therefore, certain plant flavonoids or plant extracts with these flavonoids as major components may be beneficial to treat some skin inflammatory disorders and to protect skin from photoaging.

98 citations


Journal ArticleDOI
TL;DR: Flavanones richly exist in citrus and have been well characterized to have various bioactive properties and perturb the invasion and metastasis of lung cancer cells, thereby constituting an adjuvant treatment for metastasis control.

94 citations


Journal ArticleDOI
TL;DR: A method coupling high-performance liquid chromatography with diode-array detector (DAD) and electrospray ionization mass spectrometry (ESI) was established for the separation and characterization of flavonoids in Sophora flavescens Ait, providing an approach to rapidly characterize bioactive constituents.

76 citations


Journal ArticleDOI
TL;DR: Five geranylflavonoids, one prenylated flavonoid, and a simple flavanone were isolated from an ethanolic extract of Paulownia tomentosa fruit, with diplacone proving to be the best antioxidant, although the most cytotoxic compound.
Abstract: Five geranylflavonoids, one prenylated flavonoid, and a simple flavanone were isolated from an ethanolic extract of Paulownia tomentosa fruit. Tomentodiplacol (1), 3‘-O-methyl-5‘-methoxydiplacol (2), 6-isopentenyl-3‘-O-methyltaxifolin (3), and dihydrotricin (4) are reported from a natural source for the first time and 3‘-O-methyldiplacone (6) for the first time from the genus Paulownia. The structures of the compounds were determined by mass spectrometry, including HRMS, and by 1D and 2D NMR spectroscopy. The cytotoxicity and DPPH (2,2-diphenyl-1-picrylhydrazyl)-quenching activity of some of these compounds were tested, with diplacone proving to be the best antioxidant, although the most cytotoxic compound.

68 citations


Journal ArticleDOI
TL;DR: The construction of such recombinant strains for 5-deoxyflavanone biosynthesis offers an alternative way to biochemically characterize flavonoid biosynthetic enzymes and promising production platforms for the biosynthesis of such high-value natural products.
Abstract: Flavanones are the common precursors of plant polyphenolic compounds collectively known as flavonoids. Leguminous plants have evolved a distinct class of flavanone molecules, known as 5-deoxyflavanones that play important roles in their symbiotic interactions. A four-step metabolic circuit was constructed in Escherichia coli with plant genes from heterologous origins: 4-coumarate:coenzyme A ligase from Petroselinum crispum, chalcone synthases (CHS) from Medicago sativa and Petunia x hybrida and chalcone reductase and chalcone isomerase from M. sativa. Evaluation of the different recombinant strains in shake flask experiments demonstrated that P. hybrida rather than M. sativa CHS resulted in the highest liquiritigenin production levels in glucose minimal medium, starting from precursor p-coumaric acid. Expression of the same recombinant pathway in Saccharomyces cerevisiae resulted in the accumulation of both 5-hydroxyflavanone and 5-deoxyflavanone, with the yields of the later lower than that achieved in E. coli. Other phenylpropanoid acid precursors, such as cinnamic acid and caffeic acid could also be metabolized through the recombinant pathway, yielding corresponding 5-deoxyflavanone compounds. The construction of such recombinant strains for 5-deoxyflavanone biosynthesis offers an alternative way to biochemically characterize flavonoid biosynthetic enzymes and promising production platforms for the biosynthesis of such high-value natural products.

57 citations


Journal ArticleDOI
TL;DR: C Cultures of Saccharomyces cerevisiae expressing recombinant flavonoid enzymes, including 4-coumaroyl:CoA ligase (4CL), chalcone synthase (CHS), ChI, and flavanone 3beta-hydroxylase (FHT), produced novel flavanones and dihydroflavonols when fed with a number of aromatic acrylic acids.

54 citations


Journal ArticleDOI
TL;DR: Flavanone and 2'-OH flavanone were evidenced by its inhibition on the growth of A549 and Lewis lung carcinoma cells in vivo as well as with anti-cancer drug, doxorubicin.
Abstract: Natural products, including flavonoids, are suggested to be involved in the protective effects of fruits and vegetables against cancer However, studies concerning the effect of flavonoids frequently lacked data regarding to flavanones In this study, we investigated the inhibitory effect of flavanone compounds, including flavanone, 2′-OH flavanone, 4′-OH flavanone, 6-OH flavanone, naringin and naringenin, on cell growth of various cancer cells We determined that flavanone and 2′-OH flavanone inhibited cell growth of A549, LLC, AGS, SK-Hepl and HA22T cancer cells, while other flavanones showed little or no inhibition We evaluated growth-inhibitory activity of flavanone and 2′-OH flavanone against highly proliferative human lung cancer cells (A549) via anchorage-independent and -dependent colony formation assay, and further showed that treatment of flavanone resulted in a G1 cell cycle arrest with reduction of cyclin D, E and cyclin-dependent kinase (CDK) 2, while treatment of 2′-OH flavanone led to a G2/M phase accumulation with reduction of cyclin B, D and Cdc2 Moreover, we demonstrated the improvement effect of flavanone and 2′-OH flavanone with anti-cancer drug, doxorubicin, on A549 cells Finally, flavanone and 2′-OH flavanone were evidenced by its inhibition on the growth of A549 and Lewis lung carcinoma cells in vivo

Journal ArticleDOI
TL;DR: Results suggest that flavone, flavonol, and flavanone act as competitive antagonists of the AhR, while catechin associates withThe AhRc and indirectly exhibits its antagonistic effects.

Journal ArticleDOI
TL;DR: Three protected derivatives of the flavonol 6-prenylquercetin have been synthesized in short reaction sequences featuring the title processes as key steps.
Abstract: Starting from the readily available parent flavonoids, the flavanone 6-prenylnaringenin, the isoflavone 6-prenylgenistein (wighteone, erythrinin B) and a protected derivative of the flavonol 6-prenylquercetin (gancaonin P) have been synthesized in short reaction sequences featuring the title processes as key steps.

Journal ArticleDOI
TL;DR: It was for the first time suggested that the binding of flavonoids to the heme moiety or a protein region of catalase contributes to the enhancement ofCatalase activity.
Abstract: The antioxidative activity of flavonoids depends upon a combination of many factors, such as the concentration and chemical structure of the flavonoids and the arrangement of functional groups in their structure. In the present study, to evaluate the antioxidative effect of several types of flavonoids on catalase activity at a physiological H2O2 concentration, a chemiluminescent (CL) method was used. The H2O2/luminol-dependent CL intensity in a system containing 3.7 nM catalase and low concentrations (10-100 nM) of green tea flavanols (epigallocatechin gallate; EGCG and epicatechin gallate; EG) was enhanced in comparison with that of a system without catalase, suggesting that EGCG and EG partially suppressed catalase activity. On the other hand, flavone and flavonols such as rutin (a 3-glycosidic flavone), quercitrin (a 3-glycosidic flavonol), myricetin, and kaempferol (flavonols), respectively, lowered the CL intensity to a greater extent at low concentrations (<0.1 microM) when catalase was present than when catalase was absent, indicating that these flavonoids activate catalase. In addition, isoflavone and flavanone such as daidzein and naringenin, respectively, exhibited weak antioxidative activities against H2O2 without any effect on the catalase activity over a wide range of flavonoid concentrations (0.04-0.4 microM). From these results, it was for the first time suggested that the binding of flavonoids to the heme moiety or a protein region of catalase contributes to the enhancement of catalase activity.

Journal Article
TL;DR: The data suggest that the same compound, quercetin, can act as a prooxidant, but also, it may prevent damage in cells caused by free radicasl, due to the induction of GSH, by forming less harmful complex.
Abstract: Flavonoids are phytochemicals exhibiting a wide range of biological activities, among which are antioxidant activity, the ability to modulate activity of several enzymes or cell receptors and possibility to interfere with essential biochemical pathways. Using human laryngeal carcinoma HEp2 cells and their drug-resistant CK2 subline, we examined the effect of five flavonoids, three structurally related flavons (quercetin, fisetin, and myricetin), one flavonol (luteolin) and one glycosilated flavanone (naringin) for their (a) ability to inhibit mitochondrial dehydrogenases as an indicator of cytotoxic effect (MTT test), (b) their influence on glutathione level (determined spectrophotometrically), (c) antioxidant/prooxidant effects (thiobarbituric acid-malondyaldehyde (TBA-MDA) formation as a measure of lipid peroxidation induced by flavonoids and hydrogen peroxide) and influence on cell membrane permeability (lactate dehydrogenase permeability from cell into growth media), and (d) effect on expression of cytochrome CYP1A1 (determined by Western blot analysis). Cytotoxic action of the investigated flavonoids after 72 hours of treatment follows this order: luteolin>quercetin>fisetin>naringin>myricetin. The highest non-toxic concentrations of flavonoids were established as follows: luteolin (4.12  M), quercetin (5.46  M), fisetin (5  M), naringin (38.1  M) and myricetin (41.2  M). These concentrations were used in all experiments. Our results show that CK2 were more resistant to toxic concentrations of flavonoids as compared to parental cells. Quercetin increased the total GSH level in both cell lines. CK2 cells are less perceptible to lipid peroxidation and damage caused by free radicals. Quercetin showed prooxidant effect in both cell lines, luteolin only in HEp2 cells, whereas other tested flavonoids did not cause lipid peroxidation in the tested cell lines. These data suggest that the same compound, quercetin, can act as a prooxidant, but also, it may prevent damage in cells caused by free radicasl, due to the induction of GSH, by forming less harmful complex. Quercetin treatment damaged cell membranes in both cell lines. Fisetin caused higher cell membrane permeability only in HEp2 cells. However, these two compounds did not enhance the damage caused by hydrogen peroxide. Quercetin, naringin, myricetin and fisetin increased the expression of CYP1A1 in both cell lines, while luteolin decreased basal level of CYP1A1 only in HEp2 cells. In conclusion, small differences in chemical structure of flavonoids lead to drastic change of their biological effects. These effects are strongly dependent on cell type as well as test systems used. Extensive studies on structure-function relationship of flavonoids in different test systems could provide rational approach to drug and chemopreventive agent design.

Journal ArticleDOI
TL;DR: Allergy-preventive activity was demonstrated for an extract of resins from Xanthorrhoea hastilis R. BR.
Abstract: Allergy-preventive activity was demonstrated for an extract of resins from Xanthorrhoea hastilis R BR in a search for allergy-preventive substances from natural sources By bioassay-directed fractionation of this plant extract, a new flavanone, 3',5'-dihydroxy-7,4'-dimethoxyflavanone (1), and two new chalcones, 3,5,2'-trihydroxy-4,4'-dimethoxychalcone (2) and 5,2'-dihydroxy-3,4,4'-trimethoxychalcone (3), were isolated together with five known compounds, 5'-hydroxy-7,3',4'-trimethoxyflavanone (4), 3'-hydroxy-7,4'-dimethoxyflavanone (5), liquiritigenin 7-methyl ether (6), 4,2'-dihydroxy-4'-methoxychalcone (7) and sakuranetin (8) The structures of 1, 2 and 3 were elucidated by spectroscopic methods All of these compounds showed allergy-preventive effects

Journal ArticleDOI
TL;DR: Two new flavanone glucosides were isolated from the stems and leaves of Jasminum lanceolarium and screened for their in vitro antioxidant activity through DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging assay.
Abstract: Two new flavanone glucosides, (2S)-5,7,3′,5′-tetrahydroxy-flavanone 7-O-β-D-allopyranoside (1) and (2S)-5,7,3′,5′-tetrahydroxy-flavanone 7-O-β-D-glucopyranosie (2) were isolated from the stems and leaves of Jasminum lanceolarium, along with five known compounds: Betulinaldehyde (3), betulinic acid (4), betulin (5), syringin (6) and Liriodendrin (7). Their structures were determined on the basis of spectroscopic and chemical methods. The isolated compounds were screened for their in vitro antioxidant activity through DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging assay. Compounds 2 demonstrated significant radical scavenging activity.

Journal ArticleDOI
01 Apr 2007-Biologia
TL;DR: This simple method is adequate for unambiguous assessment of sensitivity of bacterial strains to flavonoids by measurement of generation times of bacteria in liquid cultures.
Abstract: Antibacterial activities of various flavonoids, a group of natural plant substances, have been reported previously, however, there are contradictory data, published by various authors, regarding sensitivity of particular bacterial species to these compounds. These problems arose apparently because of using different methods by various researchers. Here we tested sensitivity of several bacterial species (Gram-positive: Bacillus subtilis, Micrococcus luteus, Sarcina sp. and Staphylococcus aureus; and Gram-negative: Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella enterica, Serratia marcescens and Vibrio harveyi) to various flavonoids: genistein and daidzein (isoflavones), apigenin (a flavone), naringenin (a flavanone) and kaempferol (a flavonol) by measurement of generation times of bacteria in liquid cultures. The presented results indicate that this simple method is adequate for unambiguous assessment of sensitivity of bacterial strains to flavonoids.

Journal ArticleDOI
TL;DR: In this paper, four new flavanone oligoglycosides, theaflavanosides I, II, III, and IV, were isolated from the seeds of Camellia sinensis.
Abstract: Four new flavanone oligoglycosides, theaflavanosides I, II, III, and IV, were isolated from the seeds of Camellia sinensis. The structures of theaflavanosides were elucidated on the basis of chemical and physicochemical evidence. Among them, theaflavanoside III was found to show hepatoprotective effect on D-galactosamine-induced cytotoxicity in primary cultured mouse hepatocytes.

Journal ArticleDOI
TL;DR: Flavanone glycosides were successfully separated from the crude extract of Poncirus trifoliata by preparative centrifugal partition chromatography with a two-phase solvent system composed of ethyl acetate-acetonitrile-water.
Abstract: Flavanone glycosides were successfully separated from the crude extract of Poncirus trifoliata by preparative centrifugal partition chromatography with a two-phase solvent system composed of ethyl acetate-acetonitrile-water (3:2:5, v/v/v). Naringin (50.0 mg), neoponcirin (16.8 mg), and poncirin (71.9 mg) were purified from the 524 mg crude extract in only one step. The purities of the isolated compounds were determined to be over 90% by HPLC analysis and their structures were elucidated by (1)H NMR, (13)C NMR, and ESI-MS.

Journal ArticleDOI
TL;DR: Molasses of tangerine orange is a promising source of flavonoid glycosides and is isolated and identified its organic constituents to elucidate a use for this molasses waste.
Abstract: Molasses of tangerine orange (Citrus unshiu Markovich) is obtained as a waste product in the course of tangerine orange juice production. This molasses is expected to be a useful source of organic compounds such as flavonoids and limonoids. To elucidate a use for this molasses waste, we isolated and identified its organic constituents. Two new flavanonol glycosides were isolated from tangerine orange molasses, along with several flavonoids such as hesperidine, narirutin, eriodictyol, 3',4',5,6,7,8-hexamethoxy-3-O-beta-D-glucopyranosyloxyflavone, and 3',4',5,6,7,8-hexamethoxy- 3-beta-D-[4-O-(3-hydroxy-3-methylglutaloyl)]-glucopyranosyloxyflavone, and limonoids such as limonin, nomilin, and cyclic peptide, citrusin III. The structures of the new flavanonol glycosides were determined as (2R,3R)-7-O-(6-O-alpha-L-rahmnopyranosyl-beta-D-glucopyranosyl)-aromadendrin and 7-O-(6-O-alpha-L-rahmnopyranosyl-beta-D-glucopyranosyl)-3,3',5,7-tetrahydroxy-4'-methoxyflavanone by means of spectral analyses using (1)H-NMR, (13)C-NMR, and 2D-NMR. Of these compounds, flavanone glycoside, hesperidin and narirutin were isolated as the main constituents. Thus, molasses is a promising source of flavonoid glycosides.

Journal ArticleDOI
TL;DR: IT-MS operated in the positive mode was applied for the rapid characterization/quantification of the flavanones in extracts from Fructus aurantii and showed that the IT-MS is a powerful tool for the structural characterization and quantitative determination offlavanone aglycones.
Abstract: it-ms operated in the positive mode was applied for the rapid characterization/ quantification of the flavanones in extracts from fructus aurantii. apci-ms and cid ms/ms provide unequivocal molecular weight (mw) data of these compounds and useful information about their structures (diagnostic fragment ions). main fragment pathways include neutral losses of h,o-2, c2h2o, and b-ring as well as a retro-diels-alder (rda) fragment giving rise to [(1,3)a + h](+), [b-1,b-3 + h](+), and [b-1,b-4-h-2 + h](+) ions, which form the characteristic ms/ms "fingerprint" of flavanone aglycones. when screening extracts of f. aurantii for flavanone aglycones, eight target compounds were characterized using this fingerprint. meanwhile, esi-ms in full-scan mode was developed and validated for the quantification of the main flavanone aglycones in f. aurantii. this method is simple, accurate, fast and requires only 16 min per sample for direct detection and quantification of naringenin and hesperetin. all the results and these characteristic fragments showed that the it-ms is a powerful tool for the structural characterization and quantitative determination of flavanone aglycones.

Journal ArticleDOI
TL;DR: In this paper, two cyclized C-geranylated flavonoids, the dihydroflavonol bonanniol C (4a) and the flavanone bonannione B (6a), were isolated as minor compounds from the aerial parts of Bonannia graeca (Umbelliferae).


Journal Article
TL;DR: The 2,3-double bond in ring C, appropriate hydroxyls, ring B attached at position 2, hydroxys in position 3, ortho-substituting hydroxyyls in ring B may be key structural requirements of flavonoids for potent cytotoxicity to HL-60 cells.
Abstract: Background & objective Flavonoids, with some beneficial biological activities, exist extensively in foods and herbal products This study was to evaluate the effects of 23 flavonoids on the proliferation of leukemia cell line HL-60, and elucidate the structure-activity relationship (SAR) Methods HL-60 cells were treated with 23 flavonoids with high purity and definite structure Cell proliferation was detected by MTT assay The 50% inhibition concentrations (IC50) of the 23 flavonoids were calculated The effects of particular structures on IC50 were evaluated Results Most of the 23 flavonoids inhibited the proliferation of HL-60 cells distinctly, and the effects were enhanced along with increasing concentrations However, the intensity of their effects were different, which were arranged from strong to weak as follows:3,6-dihydroxyflavone > luteolin > geraldol > 2'-hydroxyflavanone > apigenin > 3,7-dihydroxyflavone > myricetin > fisetin > baicalein > quercetin > flavanone > chrysin > galangin > 4'-hydroxyflavanone > 6-hydroxyflavone > genistein > flavone >7-hydroxyflavone > daidzein > hesperetin > naringenin The 2,3-double bond in ring C, appropriate hydroxyls, ring B attached at position 2, hydroxyls in position 3, ortho-substituting hydroxyls in ring B were related to enhanced inhibitory effects of flavonoids on the proliferation of HL-60 cells, while the lack of 2,3-double bond, deficiency or redundancy of hydroxyl groups, hydroxyl group in position 5, 7 or meta-substituting hydroxyls in ring B, isoflavone structure were related to reduced inhibitory effects of flavonoids Conclusion The 2,3-double bond in ring C, appropriate hydroxyls, ring B attached at position 2, hydroxyls in position 3, ortho-substituting hydroxyls in ring B may be key structural requirements of flavonoids for potent cytotoxicity to HL-60 cells

Journal ArticleDOI
TL;DR: From the results, a kinetic model for the reaction of reduction of the DPPH* by the isolated p-catechol group in flavanone type structures is proposed, and two explicit kinetics equations have been derived that fit very well the experimental data points acquired from all assayed compounds, thus allowing an accurate determination of the corresponding rate and stoichiometric constants.
Abstract: The time evolution of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) concentration in four solvents (methanol, ethanol, propanol, and acetonitrile) during its reduction by three flavanones containing an isolated p-catechol group (taxifolin, eriodyctiol, and fustin) as well as the time evolution of the mass spectra of the reaction mixture has been determined by spectrophotometry and liquid mass spectrometry, respectively. In alcoholic solvents the reduction curves consisted of an initial short but fast kinetics step followed by a longer slow kinetics step; in contrast, in acetonitrile the reduction curves completely lacked the slow kinetics step. From the results, a kinetic model for the reaction of reduction of the DPPH• by the isolated p-catechol group in flavanone type structures is proposed. According to this model, the p-catechol group rapidly transfers two hydrogen atoms to DPPH•, through a fast rate constant k1, yielding the corresponding o-quinone. Then, the intermediate o-quinone forms an adduct wi...


Journal ArticleDOI
TL;DR: A new flavanone glycoside was isolated from the EtOAc extract of dried immature fruit of Poncirus trifoliata and exhibited considerable inhibitory activity against lipopolysaccharide (LPS)-induced prostaglandin E(2) (PGE) and interleukin-6 (IL-6) production, and mRNA expression in RAW 264.7 murine macrophage cells.
Abstract: A new flavanone glycoside, (2R)-5-hydroxy-4'-methoxyflavanone-7-O-{beta-glucopyranosyl-(1-->2)-beta-glucopyranoside} (1), was isolated from the EtOAc extract of dried immature fruit of Poncirus trifoliata, together with three known compounds, (2S)-poncirin (2), (2S)-naringin (3), and (2S)-poncirenin (4). The structure of compound 1 was elucidated by spectroscopic data analysis, including 1D and 2D NMR experiments. Among the isolates, compound 2 exhibited considerable inhibitory activity against lipopolysaccharide (LPS)-induced prostaglandin E(2) (PGE(2)) and interleukin-6 (IL-6) production, and mRNA expression in RAW 264.7 murine macrophage cells.

Journal ArticleDOI
TL;DR: In this article, two novel flavonoids, myrsininone A (1), an isoflavone and myrsINinone B (2), a flavanone with very strong antibacterial activities, were isolated from the stems of Myrsine africana L. Their structures were elucidated by extensive spectroscopic analyses.
Abstract: Two novel flavonoids, myrsininone A (1), an isoflavone and myrsininone B (2), a flavanone, with very strong antibacterial activities, were isolated from the stems of Myrsine africana L. Their structures were elucidated by extensive spectroscopic analyses. The antibacterial activities were determined by modified Resazuric MIC methods.

Journal ArticleDOI
TL;DR: In this paper, the kinetic energy of photosensitized oxidation of the flavanone naringin and its chalcone isomer (4′-rhamnoglucosyl-2′,6′,4-trihydroxychalcone, CH) in neutral and 1mM NaOH ethanol solutions was studied using Rose Bengal as photosensitizer.
Abstract: The kinetic of the O 2 ( 1 Δ g )-photosensitized oxidation of the flavanone naringin (7-rhamnoglucosyl-4′,5-dihydroxyflavanone, FL) and its chalcone isomer (4′-rhamnoglucosyl-2′,6′,4-trihydroxychalcone, CH) in neutral and 1 mM NaOH ethanol solutions was studied using Rose Bengal as photosensitizer. The rate constants for the chemical quenching of O 2 ( 1 Δ g ) by the flavonoids ( k r ) were determined using either UV–vis absorption spectroscopy or HPLC techniques, and for the total (physical + chemical) quenching ( k t ) were determined using time-resolved phosphorescence detection of O 2 ( 1 Δ g ) at 1270 nm. A larger reactivity towards O 2 ( 1 Δ g ) of CH than for FL in neutral ethanol solutions was observed, due to the extra conjugated double bond in CH. However, in alkaline media the reactivity of both isomers was larger than in neutral conditions. This behavior was associated to the increment of electron density by the formation of a carbanion in FL and to the presence of the extended conjugated π-system in the CH isomer by deprotonation of phenolic groups. In all cases, the formation of 4-hydroxybenzoic acid as ending product was detected by HPLC. Based on reported mechanisms of O 2 ( 1 Δ g )-mediated oxidation of flavonoids, the formation of 7-rhamnoglucosyl-5,4′-dihydroxyflavonol as primary photo-oxidation product was proposed. The reactivity towards O 2 ( 1 Δ g ) of the aglycone of naringin (5,7,4′-trihydroxyflavanone or naringenin, NG) in alkaline conditions was lower than for the parent naringin, due to incapability of NG to form a carbanion species. These results are expected to have significance in biosynthesis, antioxidant properties and stability of naturally occurring flavonoids.