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PubMed1998

Stereochemistry and putative origins of flavanones found in post-administration urine of the traditional Chinese remedies shosaiko-to and daisaiko-to.

Optically active flavanones, dihydrowogonin and dihydrooroxylin A, were found in the urine of healthy volunteers who orally received the traditional Chinese remedies Shosaiko-to and Daisaiko-to on separate occasions. These remedies, which consisted of dried extracts of Scutellariae Radix and other herbs, contained the metabolic precursors of the flavanones, but not the flavanones themselves, in stoichiometrically sufficient amounts. Structures and stereochemistry of the flavanones were elucidated by UV, circular dichroism (CD), electron impact (EI)-MS and 1H-NMR analyses, showing that the biotransformations from the corresponding flavones, wogonin and oroxylin A, were stereoselective with a preference for the S-enantiomers. The putative origins of the flavanones were confirmed in terms of pharmacokinetics. Renal excretion-time data of the flavanones and the flavones suggested that the stereoselective transformations might have occurred in the intestinal tract as a result of microfloral metabolism before absorption.

Adult↗

PubMed2003

Chiral separation of diastereomeric flavanone-7-O-glycosides in citrus by capillary electrophoresis.

The 2S- and 2R-diastereomers of major flavanone-7-O-glycosides found in sweet orange (Citrus sinensis), mandarine (Citrus deliciosa), grapefruit (Citrus paradisi), lemon (Citrus limon), and sour or bitter orange juice (Citrus aurantium) were separated for the first time by chiral capillary electrophoresis (CE) employing various buffers with combined chiral selectors. Native cyclodextrins (CDs), neutral and charged CD derivatives were examined as chiral additives to the background electrolyte (BGE). Separation efficiency has not proved satisfactory with one single CD as chiral selector in the buffer, a full and simultaneous separation could often be achieved only by using combined buffer with two different CDs. Chiral separation of major flavanones in sweet orange, mandarine and grapefruit juices raised more difficulties than in lemon and sour orange juices as narirutin will not readily build complexes with most CDs. Diastereomeric flavanones of mature and immature grapefruits were compared and some differences were found: naringin showed different diastereomeric ratio and 2S-prunin appeared only in immature grapefruit. Marmalade was also examined by chiral CE. Its major flavanones corresponded to flavanone pattern of mixed sour and sweet oranges.

Citrus↗

PubMed2003

Separation of some chiral flavanones by micellar electrokinetic chromatography.

Micellar electrokinetic chromatography (MEKC) was applied for enantioseparation of selected flavanones, including naringin, hesperidin, neohesperidin, naringenin, hesperetin, pinostrobin, isosakuranetin, eriodictyol, and homoeriodictyol. gamma-Cyclodextrin (gamma-CD) and sodium cholate (SCh) were used as chiral modifiers inducing enantioselectivity to the background electrolyte. From among many investigated selectors only these two appeared to possess the best enantioselective properties in respect to studied flavanones. The mechanisms of their action are a little different; SCh used above critical micelle point concentration forms chiral micelles itself while gamma-CD is deprived of this property and requires addition of surfactants as, e.g., sodium dodecyl sulfate. It was found that SCh enables separation of flavanone glycosides diastereomers while separation of enantiomers of flavanone aglycones may be achieved with gamma-CD. Consideration of structural relation led to the suggestion that interaction of sugar moiety of glycosides with SCh micelles give rise to chiral recognition. MEKC appeared to be a suitable and efficient analytical tool to follow enantiomeric composition of flavanones.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed2003

Flavanone 3-hydroxylase expression in Citrus paradisi and Petunia hybrida seedlings.

Petunia hybrida and Citrus paradisi have significantly different flavonoid accumulation patterns. Petunia sp. tend to accumulate flavonol glycosides and anthocyanins while Citrus paradisi is known for its accumulation of flavanone diglycosides. One possible point of regulation of flavanone metabolism is flavanone 3-hydroxylase (F3H) expression. To test whether this is a key factor in the different flavanone usage by Petunia hybrida and Citrus paradisi, F3H mRNA expression in seedlings of different developmental stages was measured using semi-quantitative RT-PCR. Primers were designed to conserved regions of F3H and used to amplify an approximately 350 bp segment for quantitation by PhosphorImaging. Primary leaves of 32 day old grapefruit seedlings and a grapefruit flower bud had the highest levels of F3H mRNA expression. Petunia seedlings had much lower levels of F3H mRNA expression relative to grapefruit. The highest expression in petunia was in primary leaves and roots of 65 day old seedlings. These results indicate that preferential use of naringenin for production of high levels of flavanone glycosides in young grapefruit leaves cannot be attributed to decreased F3H mRNA expression.

Amino Acid Sequence↗

PubMed2003

Antitumor agents. 221.1 buceracidins A and B, two new flavanones from Bucida buceras.

As part of a study on antitumor agents from rainforest plants, two new flavanones, buceracidin A (1), 5,2'-dihydroxy-3-methoxy-6,7-(2' ',2' '-dimethylchromene)flavanone, and buceracidin B (2), 5,2'-dihydroxy-6,7-(2' ',2' '-dimethylchromene)flavanone, were isolated together with four known prenylated flavanones, minimiflorin (3), 3-hydroxyminimiflorin (4), 3-methoxyminimiflorin (5), and mundulinol (6), from Bucida buceras. The structures of buceracidins A and B were elucidated from detailed 2D NMR analyses. Among the six flavanones, 3, 5, and 6 were marginally cytotoxic in a human tumor cell line panel.

Antineoplastic Agents, Phytogenic↗

PubMed2006

Pharmacokinetics of the citrus flavanone aglycones hesperetin and naringenin after single oral administration in human subjects.

BACKGROUND AND OBJECTIVE: 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. DESIGN: 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 C(max), T(max), AUC(0-t), AUC(0-infinity), CL/F, V/F, t(1/2), MRT, A(e), A(e)((0-24)), and R(max) were calculated from their plasma or urine concentrations. RESULTS: 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 (C(max)) 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 AUC(0-infinity) 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. CONCLUSIONS: 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.

Administration, Oral↗

PubMed2025

Targeting the "bitterness gene" by genome editing abolishes synthesis of bitter flavanones in citrus; prospects for new varieties and extended climates for cultivation.

Bitterness in citrus fruit is conferred by flavanone-neohesperidosides, whose accumulation is catalyzed by a single enzyme flavanone-7-O-glucosides-1,2-rhamnosyltransferase (1,2RhaT), expressed in both leaves and fruit. To eliminate citrus bitterness, we used CRISPR/Cas9 genome editing to inactivate the 1,2RhaT gene in grapefruit (Citrus paradisi) and "Carrizo" citrange (Citrus sinensis × Citrus trifoliata). Edited lines displayed frameshift mutations that introduced premature stop codons, effectively abolishing the synthesis of the bitter neohesperidosides naringin, neohesperidin, and poncirin. Metabolomic analyses in leaves from 1,2RhaT-mutant lines confirmed the absence of bitter flavanone-neohesperidosides and a compensatory increase in the tasteless flavanone-rutinosides hesperidin, didymin, and narirutin. Since 1,2RhaT is encoded by a single gene, our findings in leaves are expected to be identical for fruit and thus demonstrate a strategy for developing non-bitter citrus cultivars while retaining health-benefitting flavonoid levels. Furthermore, cold-hardy citrus species that are currently unacceptably bitter due to high flavanone-neohesperidoside levels may become useful sources for introduction of cold-hardiness following inactivation of the 1,2RhaT gene. This approach thus paves the way for expanding grapefruit markets and breeding cold-hardy, palatable citrus varieties that are better suited to a wider range of climates.

Flavanones↗

PubMed2000

Bioavailability of the flavanone naringenin and its glycosides in rats.

Naringenin, the predominant flavanone in grapefruit, mainly occurs as glycosides such as naringenin-7- rhamnoglucoside or naringenin-7-glucoside. This study compared kinetics of absorption of naringenin and its glycosides in rats either after a single flavanone-containing meal or after adaptation to a diet for 14 days. Regardless of the diet, circulating metabolites were glucurono- and sulfoconjugated derivatives of naringenin. The kinetics of absorption of naringenin and naringenin-7-glucoside were similar, whereas naringenin-7-rhamnoglucoside exhibited a delay in its intestinal absorption, resulting in decreased bioavailability. After naringenin-7-glucoside feeding, no glucoside was found in the cecum. However, after feeding naringenin-7-rhamnoglucoside, some naringenin-7-rhamnoglucoside accumulated in cecum before being hydrolyzed by intestinal microflora. Adaptation to flavanone diets did not induce accumulation of plasma naringenin. Moreover, flavanone cecal content markedly decreased after adaptation, and almost no naringenin-7-rhamnoglucoside was recovered after naringenin-7-rhamnoglucoside feeding, suggesting that an adaptation of cecal microflora had occurred. Overall, these data indicate that flavanones are efficiently absorbed after feeding to rats and that their bioavailability is related to their glycosidic moiety.

Absorption↗

PubMed2006

[The extraction and identification of total flavanone from longan pericarp].

OBJECTIVE: In order to make use of the resources of total flavanone in pericarp of longan. METHODS: The flavonids were extracted with ethanol. Used spectrophotometry to check the flavanone. RESULTS: The total flavanone in the pericarp was 1.101 mg/ml and the rate of recovery was 99.98%. CONCLUSION: The extraction and purifying methods in this experiment can get the outcome and the purity of the flavanone very high. This method is a purely physical process and has not any pollution. It is an ideal way to extract the flavanone of longan skin.

Drugs, Chinese Herbal↗

PubMed2000

The monomeric polypeptide comprises the functional flavanone 3beta-hydroxylase from Petunia hybrida.

Flavanone 3beta-hydroxylase catalyzes the Fe(II)/oxoglutarate-dependent hydroxylation of (2S)-flavanones to (2R,3R)-dihydroflavonols in the biosynthesis of flavonoids, catechins and anthocyanidins. The enzyme had been partially purified from Petunia hybrida and proposed to be active as a dimer of roughly 75 kDa in size. More recently, the Petunia 3beta-hydroxylase was cloned and shown to be encoded in a 41655 Da polypeptide. In order to characterize the molecular composition, the enzyme was expressed in a highly active state in Escherichia coli and purified to apparent homogeneity. Size exclusion chromatographies of the pure, recombinant enzyme revealed that this flavanone 3beta-hydroxylase exists in functional monomeric and oligomeric forms. Protein cross-linking experiments employing a specific homobifunctional sulfhydryl group reagent or the photochemical activation of tryptophan residues confirmed the tendency of the enzyme to aggregate to oligomeric complexes in solution. Thorough equilibrium sedimentation analyses, however, revealed a molecular mass of 39. 2+/-12 kDa for the recombinant flavanone 3beta-hydroxylase. The result implies that the monomeric polypeptide comprises the catalytically active flavanone 3beta-hydroxylase of P. hybrida, which may readily associate in vivo with other proteins.

Chromatography, Gel↗

PubMed1999

Antibacterial and antifungal flavanones from Eysenhardtia texana.

An activity-guided fractionation of a methanol-dichloromethane extract obtained from the aerial parts of Eysenhardtia texana led to the isolation of two novel antibacterial and antifungal flavanones together with a known flavanone. Their structures were established as 4',5,7-trihydroxy-8-methyl-6-(3-methyl-[2-butenyl])-(2S)-flavanone, 4',5,7-trihydroxy-6-methyl-8-(3-methyl-[2-butenyl])-(2S)-flavanone and 4',5-dihydroxy-7-methoxy-6-(3-methyl-[2-butenyl])-(2S)-flavanone on the basis of their UV, 1D and 2D-NMR spectra.

Anti-Bacterial Agents↗

PubMed1979

Flavanone synthase from Petroselinum hortense. Molecular weight, subunit composition, size of messenger RNA, and absence of pantetheinyl residue.

Flavanone synthase from irradiated cell suspension cultures of parsley was purified to apparent homogeneity. Molecular weights of about 77 000 for the enzyme and about 42 000 for the subunits were determined respectively by sedimentation-equilibrium measurements and disc-gel electrophoresis in the presence of dodecyl sulfate. A specific antiserum was prepared for the enzyme and was used in an assay for flavanone synthase mRNA activity in partially purified RNA preparations. The apparent molecular size of flavanone synthase mRNA was estimated by sucrose gradient centrifugation and gel electrophoresis under partially denaturing conditions. Values of about 17 S and Mr = 0.62 X 10(6) were obtained. The fractionation patterns suggested that flavanone synthase mRNA was homogeneous in size. All together, the results support the idea that the enzyme is composed of two subunits which are probably identical. Amino acid analysis and a microbial assay were carried out to test the possible occurrence of cysteamine, beta-alanine, and pantothenate in the enzyme. The results were negative, indicating the absence of pantetheine or a similar residue. The possible similarity in mechanism between flavanone synthase and 3-oxoacyl-(acyl carrier protein) synthase is discussed.

Acyltransferases↗

PubMed1979

The bilary excretion of flavanones in the rat.

1. The major biliary metabolites of flavanones in the rat have been identified by chromatographic and spectral methods. 2. Evidence is presented that flavanones and flavanone glycosides, following oral or parenteral administration, undergo glucuronylation and are selectively excreted via the bile. 3. Flavanone glycosides but not unconjugated aglycones may be excreted to a significant extent in bile. 4. The percentage of parenterally administered flavanones excreted in bile varies inversely with the amount administered.

Animals↗

PubMedDate not supplied

Antiproliferative and cytotoxic effects of N,N-diethylaminoethyl ethers of flavanone oximes: a comparison with anthracycline(s), anthraquinone and nitroxides action.

Since flavanone oximes derivatives (ethers) have been shown to modulate the growth of Yoshida Sarcoma cells in vivo and to induce apoptosis, the effects of these substances on immortalized cell lines growth were examined. Cell viability and sensitivity to investigated substances was measured by the modified tetrazolium salt (MTT) assay. The antiproliferative effects were expressed as IC50 and IC90, respectively. There were very substantial differences in the dose-dependency of the observed antiproliferative and cytotoxic effects. The structure-activity relationship was evident and revealed that the substitution at B-ring of molecule seems to be an important factor in flavanone oxime (ether) potency. Compared to anticancer drugs (doxorubicin, aclarubicin and mitoxantrone) flavanone oximes displayed cytotoxicity at considerably higher concentrations. The antiproliferative action of the investigated model nitroxides depended on the free radical part of the molecule. N-hydroxy derivative (reduced cation form) did not influence cells proliferation and nor display any cytotoxicity at the applied range about 60 times higher than those of flavanone derivatives. Taken together it seems reasonable to suggest that flavanone oxime(s) (ethers) as compared with antracycline(s), anthraquinone and nitroxides might be especially good candidates for in the future development of new therapeutic techniques.

3T3 Cells↗

PubMed2005

Efficient production of (2S)-flavanones by Escherichia coli containing an artificial biosynthetic gene cluster.

For the fermentative production of plant-specific flavanones (naringenin, pinocembrin) by Escherichia coli, a plasmid was constructed which carried an artificial biosynthetic gene cluster, including PAL encoding a phenylalanine ammonia-lyase from a yeast, ScCCL encoding a cinnamate/coumarate:CoA ligase from the actinomycete Streptomyces coelicolor A3(2), CHS encoding a chalcone synthase from a licorice plant and CHI encoding a chalcone isomerase from the Pueraria plant. The recombinant E. coli cells produced (2S)-naringenin from tyrosine and (2S)-pinocembrin from phenylalanine. When the two subunit genes of acetyl-CoA carboxylase from Corynebacterium glutamicum were expressed under the control of the T7 promoter and the ribosome-binding sequence in the recombinant E. coli cells, the flavanone yields were greatly increased, probably because enhanced expression of acetyl-CoA carboxylase increased a pool of malonyl-CoA that was available for flavanone synthesis. Under cultural conditions where E. coli at a cell density of 50 g/l was incubated in the presence of 3 mM tyrosine or phenylalanine, the yields of naringenin and pinocembrin reached about 60 mg/l. The fermentative production of flavanones in E. coli is the first step in the construction of a library of flavonoid compounds and un-natural flavonoids in bacteria.

Escherichia coli↗

PubMed2005

Analysis of flavanone-7-O-glycosides in citrus juices by short-end capillary electrochromatography.

The separation of the major flavanone-7-O-glycoside constituents of Citrus was carried out by isocratic reversed phase capillary electrochromatography using a 75 microm i.d. silica fused column packed with 5 microm ODS silica gel. In comparison to HPLC mode, capillary electrochromatography resolution of flavanone glycosides was obtained with a high selectivity factor. Optimum separation conditions were found using a mixture of ammonium formate (pH 2.5)--acetonitrile (8:2, v/v) as the mobile phase by the short-end injection mode. Under these conditions all the investigated flavanones were baseline-resolved within short analysis time (i.e. between 5 and 10 min). A study, evaluating the intra- and inter-day repeatability as well as limit of detection and method linearity, was developed in accordance with the analytical procedures for method validation. The developed method was applied for the quantitative analysis of flavanone glycosides in commercial fruit juices (sweet orange, lemon and grapefruit).

Acetonitriles↗

PubMed2006

Identification of O-diglycosyl flavanones in Fructus aurantii by liquid chromatography with electrospray ionization and collision-induced dissociation mass spectrometry.

This study reported the application of LC-ESI/MS method to characterize O-diglycosyl flavanones of traditional Chinese medicine Fructus aurantii(Zhiqiao) and UPLC retention parameters method to expatiate the structure-retention relationship of these O-diglycosyl flavanones. The extract of F. aurantii was found containing neoeriocitrin, isonaringin, naringin, hesperidin, neohesperidin and neoponcirin. Tandem mass spectrometric method has been utilized to elucidate structure and differentiate the interglycosidic linkage of isomeric O-diglycosyl flavanones. Based on the relative abundance of fragments formed by fragmentation at glycosidic bonds in positive ion mode and CID MS spectra of deprotonated molecule [M-H](-) in negative ion mode, the interglycosidic linkage of O-diglycosyl flavanones (flavonoid O-neohesperidosides and O-rutinosides, 1,2- and 1,6-) can be unambiguously differentiated. UPLC and a CSASS software were performed to obtain the retention parameters a, c and k values of these compounds. The Deltaa, Deltac and alpha values within compound pair naringin to neoriocitrin, neoponcirin to neohesperidin, naringin to isonaringin, neohesperidin to hesperidin, hesperidin to isonaringin, neohesperidin to naringin were calculated. We found there were some relationship between structure and retention parameters.

Chromatography, Liquid↗

PubMed2003

A rapid screening assay for inhibitors of 11beta-hydroxysteroid dehydrogenases (11beta-HSD): flavanone selectively inhibits 11beta-HSD1 reductase activity.

A rapid screening assay for chemicals inhibiting 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1 or type 2 using lysates from stably transfected cells was developed. Here, we tested a series of environmental chemicals for anti-11beta-HSD activities. Inhibition of 11beta-HSD2, which may cause cortisol-dependent activation of the mineralocorticoid receptor with sodium retention and hypertension, was observed for several compounds, with diethylcarbamate being the most potent inhibitor (IC50 6.3 microM). Abietic acid inhibited both 11beta-HSD1 (IC50 27 microM for reduction and 2.8 microM for oxidation) and 11beta-HSD2 (IC50 12 microM). Our results demonstrate for the first time that flavanone selectively inhibits 11beta-HSD1 reductase activity: this enzyme being considered as essential for the local activation of glucocorticoids and representing a potential target for the therapeutic treatment of diabetes type 2. Flavanone and 2'-hydroxyflavanone efficiently inhibited reductive (IC50 18 and 10 microM) but not oxidative activity. We observed a reduced inhibitory effect of hydroxylated flavanone derivatives and of flavones containing a double-bond between atom C2 and C3. Flavanone was specific for 11beta-HSD1 and did not inhibit 11beta-HSD2. Our results reveal that a variety of environmental compounds exert distinct inhibitory effects on 11beta-HSD1 and 11beta-HSD2, opening the possibility for selectively modulating local cortisone/cortisol availability in vivo.

11-beta-Hydroxysteroid Dehydrogenase Type 1↗