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PubMed2003

Juice components of a new pigmented citrus hybrid Citrus sinensis (L.) Osbeck x Citrus clementina Hort. ex Tan.

Fruit juice of a new pigmented citrus hybrid named Omo-31 and those of its parents clementine cv. Oroval (Citrus clementina Hort. ex Tan.) and Moro orange [Citrus sinensis (L.) Osbeck] were analyzed during fruit maturation to determine juice yield, total soluble solids (TSS), total acidity (TA), TSS/TA ratio (classical parameters of quality), and potential health beneficial components, such as vitamin C, flavanones, anthocyanins, and phenolic acids. Results showed that juice yield, TA, TSS, and TSS/TA ratio values of Omo-31 were similar to those of the Moro orange. Vitamin C content of the new hybrid was slightly higher than that of clementine and lower than that of the Moro orange, but at maturity stage no differences were observed among the three genotypes. The phenolic compounds content of the new hybrid and those of the parents and their evolution during maturation were studied. At maturity stage the amount of anthocyanins, flavanones, and hydroxycinnamic acids in Omo-31 was found to be notably higher than those of the parents. The high level of antioxidant substances makes this new fruit important for its nutritional benefits.

Anthocyanins↗
PubMed2003

Dihydrochalcones: evaluation as novel radical scavenging antioxidants.

Dihydrochalcones are a family of bicyclic flavonoids, defined by the presence of two benzene rings joined by a saturated three carbon bridge. In the present study, we systematically examined the antioxidant activities of dihydrochalcones against the stable free radical (1,1-diphenyl-2-picrylhydrazyl) and lipid peroxidation in the erythrocyte membrane. All dihydrochalcones exhibited higher antioxidant activities than the corresponding flavanones. The (1)H NMR analysis indicated that the active dihydrochalcone has a time-averaged conformation in which the aromatic A ring is orthogonal to the carbonyl group, while the inactive dihydrochalcone such as 2'-O-methyl-phloretin has a strongly hydrogen-bonded phenolic hydroxyl group, suggestive of a coplanar conformation. A hydroxyl group at the 2'-position of the dihydrochalcone A ring, newly formed by reduction of the flavanone C ring, is an essential pharmacophore for its radical scavenging potential.

Antioxidants↗
PubMed2005

Varietal and interspecific influence on micronutrient contents in citrus from the Mediterranean area.

To specify the genotypic variation of Mediterranean Citrus juices, the contents of carotenoids, flavonoids, and vitamin C were determined by high-performance liquid chromatography. A selection of orange varieties and Mandarin species from the Mediterranean area (Citrus sinensis, Citrus deliciosa Ten, and Citrus clementina Hort. ex Tan) was evaluated using carotenoid profiles and flavanones contents. Among the eight varieties of orange (Salustiana, Hamlin, Shamouti, Pera, Valencia, Maltaise, Sanguinelli, and Cara-cara) and two Mandarin species, only three cultivars (Pera, Sanguinelli, and Shamouti) and the two Mandarin species displayed a high content of vitamin A (374, 381, and 272 ER L(-1) for the three orange cultivars and 1156 and 960 retinol equivalent (RE) L(-1) for the Mandarins) due to a high content of beta-cryptoxanthin. These same Citrus were also rich in hesperidin (502, 537, 552, 767, and 754 mg L(-1), respectively). Principal component analysis allowed the Mediterranean orange varieties and Mandarin species to be differentiated on the basis of nutritional criteria. Strong correlations were observed between beta-cryptoxanthin and hesperidin (r = 0.92) and between beta-cryptoxanthin and beta-carotene (r = 0.98). In contrast, vitamin C content was not correlated with carotenoids and flavanone glycosides. The Mandarin and orange group was quite distinct. The orange varieties could be divided in two groups. In addition, a diversity tree allowed a genetic approach to differentiating Citrus cultivars on the basis of Euclidian distances. This representation showed that the hybrid Clementine was nearer to its parent Mandarin than to its parent orange, suggesting that beta-cryptoxanthin was a dominant genetic factor. With regard to vitamin A, Mandarin and its hybrid Clementine appeared to be the best Citrus species.

Ascorbic Acid↗
PubMed2001

Aromatase inhibitors from Broussonetia papyrifera.

Bioassay-guided fractionation of an ethyl acetate-soluble extract from the whole plants of Broussonetia papyrifera, using an in vitro aromatase inhibition assay, led to the isolation of five new active compounds, 5,7,2',4'-tetrahydroxy-3-geranylflavone (1), isogemichalcone C (8), 3'-[gamma-hydroxymethyl-(E)-gamma-methylallyl]-2,4,2',4'-tetrahydroxychalcone 11'-O-coumarate (9), demethylmoracin I (10), and (2S)-2',4'-dihydroxy-2' '-(1-hydroxy-1-methylethyl)dihydrofuro[2,3-h]flavanone (11), and 10 known (12-21) compounds which were also found to be active. Of these compounds, the most potent were 9 (IC(50) 0.5 microM), 11 (IC(50) 0.1 microM), isolicoflavonol (12, IC(50) 0.1 microM), and (2S)-abyssinone II (13, IC(50) 0.4 microM). Additionally, six new compounds, 5,7,3',4'-tetrahydroxy-6-geranylflavonol (2), 5,7,3',4'-tetrahydroxy-3-methoxy-6-geranylflavone (3), (2S)-7,4'-dihydroxy-3'-prenylflavan (4), 1-(2,4-dihydroxyphenyl)-3-(4-hydroxyphenyl)propane (5), 1-(2,4-dihydroxy-3-prenylphenyl)-3-(4-hydroxyphenyl)propane (6), and 1-(4-hydroxy-2-methoxyphenyl)-3-(4-hydroxy-3-prenylphenyl)propane (7), were isolated and characterized, but proved to be inactive as aromatase inhibitors, as were an additional 21 known compounds. The structures of the new compounds (1-11) were elucidated by spectroscopic methods. Structure-activity relationships in the aromatase assay were determined for the benzofurans, biphenylpropanoids, coumarins, and various types of flavonoids (chalcones, flavans, flavanones, and flavones) obtained among a total of 42 constituents of B. papyrifera.

Algorithms↗
PubMed1996

Isolation of two new antiinflammatory biflavanoids from Sarcophyte piriei.

Two new flavano flavanone glycosides, diinsininol (1) and diinsinin (2), have been isolated from the rhizome of Sarcophyte piriei, together with one known flavanone glycoside, naringenin 5-glucoside. Their structures were elucidated on spectroscopic evidence as 5,7,3',4'-tetrahydroxyflavanyl-7-O-beta-glucosyl-(4beta-8; 2beta-O-7)-eriodietyol (1) and 5,7,3',4'-tetrahydroxyflavanyl 7-O-beta-glucosyl-(4beta-8;2beta-O-7)-naringenin (2), respectively. The compounds were tested for their ability to inhibit prostaglandin synthesis, with 1 and 2 giving IC50 values of 9.20 microM and 13.14 microM, respectively, and in the inhibition of platelet-activating-factor-induced exocytosis, IC50 values of 49 and 39 microM.

Animals↗
PubMed2006

Cytotoxic compounds of Physena madagascariensis from the Madagascar rain forest paragraph sign.

Two new flavanones, remangiflavanones D and E (1 and 2), were isolated from an extract of the twigs, leaves, and flowers of Physena madagascariensis together with three known flavanones, remangiflavanones A-C (3-5), and (E)-N-feruloyltyramine (6). The structures of the new compounds 1 and 2 were established on the basis of one-dimensional and two-dimensional NMR spectroscopic data interpretation. All compounds were evaluated for their cytotoxicity in the A2780 human ovarian cancer cell line. Compound 5 was the most active with an IC50 value of 2.5 microg mL-1.

Antineoplastic Agents, Phytogenic↗
PubMed1992

Dietary modification of drug-metabolizing enzyme activities: dose-response effect of flavonoids.

The induction of drug-metabolizing enzymes for different dietary flavonoids has been shown previously. The purpose of this study was to determine the threshold effect of these components. Rats were fed diets containing flavone, flavanone, or tangeretin at different levels (20, 50, 200, 500, and 200 ppm). Flavone induced ethoxyresorufin and pentoxyresorufin dealkylase activities at 500 ppm and arylhydrocarbon hydroxylase at 200 ppm. Epoxide hydrolase and glutathion transferase were increased at 200 ppm. UDP-glucuronyl transferases were enhanced at 20 ppm. Flavanone induced pentoxyresorufin dealkylase and arylhydrocarbon hydroxylase at the greatest level. In contrast, epoxide hydrolase and conjugating enzymes were increased at the lowest dose. Significant induction was seen only for ethoxyresorufin deethylase and UDP-glucuronyl transferase with diets containing 2000 ppm tangeretin. We conclude that the threshold effect depends on the chemical structure of the flavonoid and the enzyme activity. Low threshold doses for conjugating enzymes may be important for the anticarcinogenicity properties of these compounds.

Animals↗
PubMed2004

Metabolism of 8-prenylnaringenin, a potent phytoestrogen from hops (Humulus lupulus), by human liver microsomes.

The female flowers of hops are used throughout the world as a flavoring agent for beer. Recently, there has been increasing interest in the potential estrogenic properties of hop extracts. Among the possible estrogenic compounds in hops, 8-prenylnaringenin is perhaps most significant due to its high in vitro potency exceeding that of other known phytoestrogens. Since data regarding the pharmacokinetic properties of this compound are lacking, we investigated the in vitro metabolism of 8-prenylnaringenin by human liver microsomes. A total of 12 metabolites were identified, and biotransformation occurred on the prenyl group and the flavanone skeleton. The major site of oxidation was on the terminal methyl groups, and of the two possible isomers, the transisomer was more abundant. The double bond on the prenyl group was also oxidized to an epoxide that was opened by intramolecular reaction with the neighboring hydroxyl group. On the flavanone skeleton, the major site of oxidation was at 3'position on the B ring. Other metabolites included oxidation at carbon-3 as well as desaturation of the C ring to produce 8-prenylapigenin. An unusual hydroxy quinone product formed by ipso hydroxylation of the B ring of 8-prenylnaringenin was also detected. This product was probably an intermediate for the B ring cleavage product, 8-prenylchromone.

Chromatography, Liquid↗
PubMed2004

Toxicity and cell cycle effects of synthetic 8-prenylnaringenin and derivatives in human cells.

The estrogenic flavanone rac-8-prenylnaringenin (8-PN) and 3 derivatives (rac-7-(O-prenyl)naringenin-4'-acetate (7-O-PN), rac-5-(O-prenyl)naringenin-4',7-diacetate (5-O-PN), and rac-6-(1,1-dimethylallyl)naringenin (6-DMAN) were prepared by chemical synthesis and analyzed with respect to their toxicity and possible cell cycle effects in human acute myeloid leukemia (HL-60) cells. With the exception of 5-O-PN, all the other naringenins showed only weak toxic effects at concentrations below 50 micromol/l. A cell cycle analysis over several cell generations up to 4 days was carried out using the fluorescent dye carboxyfluorescein diacetate N-succinimidyl ester (CFSE) followed by propidium iodide (PI) staining at the end of the experiment. The well-studied flavonol quercetin was included in the analysis as a reference substance. All flavonoids affected cell proliferation, but the extent and the resulting changes in the proliferation pattern were specific for each substance. In contrast to the radical scavenging activity of quercetin, the tested flavanones showed no anti-oxidative properties using several different test systems. Similarly, the mitochondrial membrane potential (DeltaPsim) was hardly effected by these compounds, while both menadione and quercetin strongly reduced the potential after 1 h of treatment. The reported chemical modification of interesting lead substances (like the strongly estrogenic 8-PN) presents a promising approach to modulate the properties of a relevant substance in a pharmacologically desirable way. The low toxicity and weak cytostatic properties of the tested naringenin derivatives is encouraging for further studies on known naringenin target molecules.

Benzimidazoles↗
PubMed2004

Flavonoid intake in relation to lung cancer risk: case-control study among women in Greece.

We have examined the role of three classes of flavonoids that are relatively common in the Greek diet (flavanones, flavan-3-ols, and flavonols) in the etiology of lung cancer using data from a case-control study among women, which was undertaken in Athens, Greece, in the late 1980s. Study subjects were 154 women with lung cancer and 145 control women with orthopedic conditions. Women reported their life-long smoking histories and average frequency of consumption, before onset of present disease, of 47 food items or beverages that collectively covered >80% of the intake of each of the energy-providing nutrients. Intakes of flavonoids were calculated using the recently published U.S. Department of Agriculture database. The data were modeled through logistic regression, controlling for energy intake and smoking. There was no indication that intake of any of the studied flavonoid categories reduces the risk of lung cancer; indeed, for flavonols there was an unexpected positive association. Thus, our study does not indicate a protective effect of flavanones, flavan-3-ols, or flavonols on lung cancer risk and indicates that the factors responsible for the protective effect of vegetables and fruits against the risk of this cancer are unlikely to belong to these flavonoid categories.

Case-Control Studies↗
PubMed2005

Screening for tyrosinase inhibitors among extracts of seashore plants and identification of potent inhibitors from Garcinia subelliptica.

The tyrosinase inhibitory activity of methanol extracts of the leaves of 39 plant species growing on the seashore of Iriomote island (Okinawa, Japan) was investigated. The extracts of Hibiscus tiliaceus, Carex pumila, and Garcinia subelliptica showed potent activity among them. The inhibitors in the extract of Garcinia subelliptica were purified by assay-guided fractionation to give two biflavonoids. These were known compounds (2R,3S-5,7,4',5'',7'',3''',4'''-heptahydroxy flavanone[3-8''] flavone and 5,7,4',5'',7'',3''',4'''-heptahydroxy[3-8''] biflavanone), although their strong inhibitory activity toward tyrosinase is revealed for the first time in this work. One of these biflavonoids (2R,3S-5,7,4',5'',7'',3''',4'''-heptahydroxy flavanone[3-8''] flavone) showed much stronger activity (IC50 2.5 microM) than that of kojic acid (IC50 9.1 microM) when L-tyrosine was used as the substrate.

Flavanones↗
PubMed1999

[Flavonoids from Beijing propolis].

OBJECTIVE: To separate and identify the active flavonoids from Beijing Propolis. METHOD: The flavonoids were isolated by column chromatography with silica gel and polyamide, purified with Sephadex LH-20, and elucidated on the basis of NMR, MS, UV, IR and CD spectra. RESULT: Six kinds of flavonoids were obtained and elucidated as I: pinostrobin, 5-hydroxy-7-methoxy-flavanone; II: pinocembrin, 5, 7-dihydroxy-flavanone; III: tectochrysin, 5-hydroxy-7-methoxy-flavone; IV: chrysin, 5, 7-dihydroxy-flavone; V: izalpinin, 5-hydroxy-7-methoxy-flavonol and VI: galangin, 5, 7-dihydroxy-flavonol. CONCLUSION: Compounds I, II, III and V were found for the first time from Beijing Propolis.

Flavanones↗
PubMed2004

[History and therapeutic evaluation of Citrus hassaku HORT. Tanaka].

The original plant of Citrus hassaku HORT. Tanaka was found at Jyoudo-Temple in Inno-shima, Hiroshima Prefecture, Japan by Ekei Shounin in the Edo Era. Today, the fresh raw fruits of C. hassaku are cultivated as a seasonal food, and the most famous producing district of the C. hassaku fruit is Wakayama Prefecture, representing about 60% of the Japanese output. The immature fruits of C. hassaku and its three main flavanone glycosides (naringin, neohesperidin and narirutin) have shown inhibitory activities on a compound 48/80-induced histamine release from mast cells, and anti-allergic effects on dinitrofluorobenzen (DNFB)-induced triphasic skin reaction in mice. The contents of the three flavanone glycosides in the immature fruits were higher than those in mature fruits of C. hassaku to skin care for patients with atopitic dermatitis showed improving effects in 76% of the patients. Similar efficacy was obtained for patients with pollinosis.

Animals↗
PubMedDate not supplied

Simultaneous quantification of adrenergic amines and flavonoids in C. aurantium, various Citrus species, and dietary supplements by liquid chromatography.

An analytical method was developed for the simultaneous quantitative analysis of 6 amines and 20 flavonoids in fruits and extracts of 30 Citrus species, including C. aurantium, near-Citrus relatives, and dietary supplements by liquid chromatography with photodiode array detection. The separation was achieved with a Phenomenex Synergi Hydro reversed-phase column using gradient mobile phase of sodium acetate buffer (pH 5.5) and acetonitrile. Elution was run at a flow rate of 1.0 mL/min and UV at 254, 280, and 330 nm. Among the amines analyzed, synephrine, the main component, was present in the levels from 0.11 to 2.0 mg/g dry weight in 21 Citrus species and 0.07 to 18.62% in dietary supplements claiming to contain C. aurantium. The flavanones and flavones were analyzed in the same Citrus samples and were species-specific. The levels of flavones were very low compared with those of flavanones. The method facilitated the simultaneous quantification of 6 amines and 20 flavonoids in various Citrus species, the distinction between the different Citrus species, and the analysis of dietary supplements containing C. aurantium.

Acetonitriles↗
PubMed2006

[Isolation and structure identification of chemical constituents from Patrinia villosa].

AIM: To study the chemical constituents of Patrinia villosa Juss. METHODS: Solvent extraction, silica gel column and preparative liquid chromatography were used to separate the chemical constituents, and the chemical structures were elucidated by physico-chemical properties and spectra data. RESULTS: Eight compounds were isolated and identified as bolusanthol B (1), (2S)-5, 7, 2', 6'-tetrahydroxy-6,8-di (gamma,gamma-dimethylallyl) flavanone (2), orotinin (3), (2S)-5, 7, 2', 6'-tetrahydroxy-6-lavandulylated flavanone (4), 3'-prenyl-apigenine (5), luteolin (6), quercetin (7) and apigenin (8). CONCLUSION: Compound 2 and 4 are new compounds, compounds 1, 3 and 5 were separated from Patrinia genius for the first time, compounds 6, 7 and 8 were isolated from Patrinia vollosa Juss for the first time.

Apigenin↗
PubMed1996

Time course of induction of rat hepatic drug-metabolizing enzyme activities following dietary administration of flavonoids.

Effects of continuous feeding flavonoids (flavone, flavanone, and tangeretin) on drug-metabolizing enzymes in rat liver were investigated to ascertain how long feeding is required to reach maximal induction and to determine whether maximal induction is maintained for a long period of feeding. In the first experiment rats received a diet containing 10 mmol flavonoid/kg dry matter for 4, 8, 16, or 32 d. The second experiment was designed to examine the time course for induction during the first 4 d. The kinetics of induction depended on the chemical structure of the flavonoid and was different from one enzyme to another. Flavone increased P450 1A and P450 2B apoproteins and stimulated many enzyme activities. A significant increase of P450 1A1/2 proteins, ethoxyresorufin O-deethylase (EROD), and methoxyresorufin O-demethylase (MROD) activities occurred as early as 6 h after the first administration, and a gradual increase was observed up to 4 d of feeding. P450 2B1/2 proteins and pentoxyresorufin O-depentylase (PROD) activity were also increased but after a lag period when compared with P450 1A1/2 proteins. EROD and MROD activities declined after 4 d, whereas PROD activity remained steady during 32 d of flavone feeding. Glutathione transferase (GST) and p-nitrophenol UDP-glucuronosyl transferase (UGT) activities were also increased. The maximal induction was reached by 4 d of feeding for UGT and after a longer duration of feeding (16 d) for GST. Flavanone treatment induced mostly P450 2B1/2 proteins and PROD, GST, and UGT activites. After 4 d of feeding, P450 2B1/2 proteins and PROD activity declined whereas GST and UGT activities remained steady. Tangeretin treatment produced changes similar to flavone but of lesser magnitude and after a longer delay.

Animals↗
PubMed2005

Analysis of antioxidant compounds in sweet orange peel by HPLC-diode array detection-electrospray ionization mass spectrometry.

HPLC-diode array detection-electrospray ionization mass spectrometry was used to determine qualitatively and quantitatively the flavonoid content of several fractions and residues of extracts of Greek navel sweet orange peel (Citrus sinensis) from the region of southern Greece (Leonidi-Tripoli). The main groups of flavonoids found according to HPLC retention times, spectral data and literature references were polymethoxylated flavones, C-glycosylated flavones, O-glycosylated flavones, O-glycosylated flavanones, flavonols and phenolic acids and their derivatives. The ethyl acetate fraction which has been shown in previous work to possess the best radical scavenging activity among the others was found to contain C-glycosylated flavones, polymethoxylated flavones, O-glycosylated flavones, O-glycosylated flavanones, two phenolic acid derivatives and two unknown compounds, all in low concentrations. The group of C-glycosylated flavones was reported for the first time in the peel of Navel sweet orange. The C-glycosylated flavones found according to their spectral characteristics and literature were 6-C-beta-glucosyldiosmin, 6,8-di-C-glucopyranosylapigenin, 6,8-di-C-beta-glucosyldiosmin and two unknown. The results suggest that the ethyl acetate fraction of navel Citrus sinensis peel consists of significant antioxidant compounds and can be used as a food additive of natural origin or a pharmaceutical supplement using as a source of peel the byproducts of the orange juice industry.

Acetates↗
PubMed2002

Activation of bone sialoprotein gene transcription by flavonoids is mediated through an inverted CCAAT box in ROS 17/2.8 cells.

Bone sialoprotein (BSP) is a major noncollagenous protein of the mineralized bone extracellular matrix that has been implicated in the nucleation of hydroxyapatite. Recent studies have shown that BSP is also expressed by osteotropic cancers suggesting BSP might play a role in the pathogenesis of bone metastases. The present study investigates regulation of BSP transcription in rat osteosarcoma ROS 17/2.8 cells by flavonoids: genistein (an inhibitor of protein tyrosine kinases), daidzein (an inactive compound of genistein), flavone, and flavanone. Genistein, daidzein, and flavone (50 microM) increased steady state levels of BSP mRNA about 1.7-fold at 12 h. From transient transfection assays using various sized BSP promoter-luciferase constructs, genistein increased luciferase activities within 12 h. Constructs including the promoter sequence nucleotides (nts) -116 to -43 (pLUC3) were found to enhance transcriptional activity approximately 2.6-fold in ROS 17/2.8 cells treated with genistein (50 microM). Daidzein, flavone, and flavanone (50 microM) also increased luciferase activities. In contrast, the tyrosine kinase inhibitors, herbimycin A and lavendustin A, which do not have a flavonoid structure, did not stimulate BSP transcription. Transcriptional stimulation by genistein was almost completely abrogated in a construct that included 2 bp mutations in the inverted CCAAT box. A monoclonal antibody against NF-YA, a CCAAT box-binding transcription factor, inhibited formation of DNA-NF-Y protein complex in gel shift assays formed by nuclear extracts of ROS 17/2.8 cells. These data suggest that the inverted CCAAT box is required for flavonoid-induced BSP expression and that the stimulatory action is dependent on the flavone structure and does not involve an inhibitory action on protein tyrosine kinase.

Animals↗