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Objectives: The Biopharmaceutics Classification System (BCS) categorizes active pharmaceutical ingredients according to their solubility and permeability properties, which are susceptible to matrix or formulation effects. The aim of this research was to evaluate the matrix effects of a hydroethanolic extract of calyces from Physalis peruviana L. (HEE) and its butanol fraction (BF), on the biopharmaceutics classification of their major compound, quercetin-3-O-rutinoside (rutin, RU)., Methods: Rutin was quantified by HPLC-UV, and Caco-2 cell monolayer transport studies were performed to obtain the apparent permeability values (P app ). Aqueous solubility was determined at pH 6.8 and 7.4., Key Findings: The P app values followed this order: BF > HEE > RU (1.77 ± 0.02 > 1.53 ± 0.07 > 0.90 ± 0.03 × 10 -5  cm/s). The lowest solubility values followed this order: HEE > RU > BF (2.988 ± 0.07 > 0.205 ± 0.002 > 0.189 ± 0.005 mg/ml)., Conclusions: According to these results, rutin could be classified as BCS classes III (high solubility/low permeability) and IV (low solubility/low permeability), depending on the plant matrix. Further work needs to be done in order to establish how apply the BCS for research and development of new botanical drugs or for bioequivalence purposes., (© 2020 Royal Pharmaceutical Society.)

Rutin, one of the metabolites of the flavonoid pathway, shows great potential in industrial applications as a key component in pharmaceutical medicines and biological pesticides. Although the genetic manipulation of transcription factors (TFs) could increase rutin levels in plants, the accompanying accumulation of structurally similar chemicals complicates industrial rutin extraction. In this study, we demonstrated remarkably elevated rutin content (3.5-4.4-fold relative to controls) in transgenic tobacco plants by overexpressing NtFLS2. The levels of other intermediates in the branch pathway did not change much except for a moderate increase of kaempferol-3-O-rutinoside. Furthermore, the transcript levels of pathway genes in transgenic lines were comparable with controls, indicating genetic engineering did not significantly alter the branch pathway. Additionally, the transgenic tobacco plants appeared normal except for a flower color change from light red to white suggesting that it could be a valuable material for industrial extraction of rutin.

Unlabelled: Quercetin is a flavonol believed to have beneficial effects on human health. Rutin, found in many plants, fruits and vegetables, is metabolized by human intestinal bacteria and converted to quercetin, where it is absorbed through the intestinal epithelium. This study aimed to isolate and characterize human intestinal bacteria capable of converting rutin to quercetin. A bacterium that can metabolize rutin was isolated from human faecal samples and identified by 16S rRNA gene sequencing. The whole-cell enzymatic activities on flavonoid glycoside and the conversion profiles of the isolate were also analysed. The bacterium was identified as Enterococcus avium EFEL009 and was shown to convert rutin to isoquercetin and then to quercetin under anaerobic conditions. Microscopic analysis revealed short chains of cocci with diameters of approx. 1 μm. β-Glucosidase was shown to be constitutively expressed in Ent. avium, while α-rhamnosidase was expressed following induction by rutin. Both enzymes were mainly localized to the cell surface. This study is the first report on the isolation of a quercetin-producing Ent. avium FEEL009, which could be a potential industrial starter bacterium., Significance and Impact of the Study: Quercetin is a member of the flavonoids family reported to have better cytoprotective abilities, stronger inhibition of lipopolysaccharide-induced nitric oxide production, and better chemoprevention than rutin. This is the first report on the isolation and characterization of Enterococcus avium EFEL009 from the human intestine which is capable of converting rutin to quercetin., (© 2015 The Society for Applied Microbiology.)

Flavonoids, the potent antioxidant and anti-inflammatory plant compounds, require deglycosylation for absorption across the intestine. Intestinal bacteria are indispensable for the hydrolysis of flavonoid diglycosides. We isolated, for the first time, three anaerobic Lactobacillus-like strains designated as MF-01, MF-02 and MF-03 from the cecum of chicken capable of converting flavonoid diglycosides into bioactive aglycones. All the isolated strains were found to be active in the conversion of quercetin-3-rhamnoglucoside (rutin) and hesperetin-7-rhamnoglucoside (hesperidin) into their aglyconic forms. No metabolites were detected after the fermentation tests with naringenin-7-rhamnoglucoside (naringin). The degradation rates of flavonoids and influence of different carbon sources, following incubation with isolated strains, were also monitored. Overall maltose resulted in rapid degradation of flavonoids. However, when organic acids (lactate, acetate, butyrate or propionate) were added to the basal medium as carbon source, flavonoid degradation was completely inhibited. Using consortium of three isolated strains, fructooligosaccharide (10 g L(-1)) supplementation was found to be imperative for preserving aglycone hesperitin while organic acids supplementation (10 g L(-1)) to the fermentation medium resulted in rapid degradation of hesperitin indicating that the metabolic fate of flavonoids may be related to the gut metabolic behavior. Butyrate and propionate also suppressed rutin deglycosylation by the consortium.

The nuclear localization of blue-staining flavanols was investigated histochemically throughout microsporogenesis in yellow cypress (Callitropsis nootkatensis (D. Don) Oerst., formerly Cupressus nootkatensis), juniper (Juniperus communis L.) and yew (Taxus baccata L.). During meiotic development, both the cytoplasm and nuclei of microspores of all species contained varying amounts of flavanols; however, the flavanols were largely confined to the nuclei in microspores just released from tetrads. Quantification by HPLC analysis indicated that, in all species, catechin and epicatechin were the dominant nuclear flavanols. At the early free microspore stage, the nuclear flavanols were barely detectable in all species, but they increased fivefold on incubation in the presence of 0.1 mM benzylaminopurine (BA) or zeatin. Histochemical studies revealed that, in addition to non-fluorescing flavanols, microspores contained yellow-fluorescing flavonoids, which yielded a distinct HPLC flavonoid profile for each species. In yellow cypress, the hydrolyzed flavonoids were identified as quercetin, apigenin, kaempferol and luteolin, whereas only quercetin and myricetin were found in microspores of juniper and in anthers of yew. Application of a UV-VIS titration technique revealed that the aglycone quercetin seems to interact more strongly with histone H3 than either glycoside rutin or kaempferol.

Quercetin, rutin, the extract of white radish sprout rich in kaempferol glycosides, and their combination were intragastrically administered to Wistar rats to investigate the interactive metabolism of these flavonoids. The combined administration of these flavonoids changed the concentrations of the metabolites in plasma as compared with the concentrations after the administration of a single compound.

Quercetinase is produced by various filamentous fungi when grown on rutin as sole carbon and energy source. We investigated on the effect of 10 phenolics and two sugars, structurally related to substrates and products of the rutin catabolic pathway, on the induction of a quercetinase activity in Penicillium olsonii. Neither the sugars (glucose and rhamnose, two constituents of rutin), nor phenolics such as protocatechuic acid, salicylic acid, 4-hydroxy-benzoic acid and phloroglucinol were inducers. Rutin (maximum activity 150 nmol/min/mL after 5 days), quercetin (70 nmol/min/mL, 3 days), phloroglucinol carboxylic acid (60 nmol/min/mL, 3 days), 2-protocatechuoylphloroglucinolcarboxylic acid (50 nmol/min/mL, 5 days), 2,6-dihydroxy-carboxylic acid (90 nmol/min/mL, 7 days) and 2,4-dihydroxy-carboxylic acid (30 nmol/min/mL, 7 days) were demonstrated to be quercetinase inducers. We propose that rutin, quercetin and 2-protocatechuoyl-phloroglucinol carboxylic acid, the product of the reaction catalysed by quercetinase, act as inducers after their catabolic transformation in phloroglucinol carboxylic acid.

The aim of this study was to explore potential transport mechanisms of rutin deca (H-) sulfonate sodium (RDS) across Caco-2 cell monolayers. As an in-vitro model of human intestinal epithelial membrane, Caco-2 cells were utilized to evaluate the transepithelial transport characteristics of this hydrophilic macromolecular compound. Bi-directional transport study of RDS demonstrated that the apparent permeability (P(app)) in the secretory direction was 1.4 approximately 4.5-fold greater than the corresponding absorptive P(app) at concentrations in the range 50.0 approximately 2,000 microM. The transport of RDS was shown to be concentration, temperature and pH dependent. In the presence of ciclosporin and verapamil, potent inhibitors of P-glycoprotein (P-gp)/MRP2, the absorptive transport was enhanced and secretory efflux was diminished. RDS significantly reduced the efflux ratio of the P-gp substrate rhodamine-123 in a fashion indicative of P-gp activity suppression, while rhodamine-123 competitively inhibited the polarized transport of the compound. In conclusion, the results indicated that RDS was likely a substrate of P-gp. Several efflux transporters, including P-gp, participated in the absorption and efflux of RDS and they might play significant roles in limiting the oral absorption of the compound. These observations offered important information for the pharmacokinetics of RDS.

In vivo expression of cell survival factors protein kinase C (PKC), nuclear factor kappaB (NFkappaB), and extracellular signal-regulated kinase (Erk), which may contribute to the development of radioresistance following radiotherapy, was looked for. Their modulation with natural compounds (curcumin, rutin or nicotinamide) was attempted in mice bearing a serially transplanted fibrosarcoma. Expression of protein kinase C was isoform specific. No translocation of any of the isozymes was noticed following gamma-irradiation as has been reported elsewhere. None of the isoforms could be significantly inhibited by the modulators. However, significant inhibition of radiation-induced ERK and NFkappaB was observed with both curcumin and nicotinamide. Therefore we conclude that use of inhibitors of MAP kinases or NFkappaB may be a more promising strategy to enhance tumour cell killing or to prevent the development of radioresistance during radiotherapy.

We investigated the absorption and metabolism of the highly soluble quercetin glycoside alphaG-rutin, a glucose adduct of insoluble rutin, using the isolated mucosa of the rat stomach and intestines equipped with the Ussing chamber. alphaG-rutin and rutin appeared in the serosal sides of the gastric body and all the intestinal mucosa after the addition of alphaG-rutin (1 mM) to the mucosal fluid. The degree of alphaG-rutin appearance was much lower in the gastric fundus than in the other parts. Quercetin was not found in the mucosal fluid of any mucosal specimen. The concentrations (microM) of alphaG-rutin and rutin in the serosal fluid as a result of transport from the mucosal side increased time-dependently and linearly with mucosal alphaG-rutin concentration (1, 10 or 100 mM). The highest transport was shown in the ileal mucosa. These results indicate that alphaG-rutin is partly hydrolyzed to rutin through the intestine and absorbed as such.

An enzyme with alpha-L-rhamnosidase activity was purified by anion exchange chromatography from an Aspergillus niger commercial preparation. The alpha-L-rhamnosidase was shown to be N-glycosylated, and had a molecular mass of 85 kD on sodium dodecylsulfate-polyacrylamide gel electrophoresis of which approximately 12% was contributed by carbohydrate. The enzyme was optimally active at pH 4.5 and 65 degrees C. When tested towards p-nitrophenyl-alpha-L-rhamnopyranoside it showed Km and Vmax values of 2.9 mM and 20.6 U mg-1, respectively whereas it was inhibited competitively by L-rhamnose (Ki 3.5 mM). Substrate specificity studies showed alpha-L-rhamnosidase to be active both on alpha-1,2 and alpha-1,6 linkages to beta-D-glucose. Moreover, the enzyme was able to release L-rhamnose from geranyl-beta-D-rutinoside and 2-phenylethyl-beta-D-rutinoside.

The mutagenicity of 13 flavonoids has been investigated with the L-arabinose forward mutation assay of Salmonella typhimurium. Each flavonoid was tested by both plate incorporation and preincubation mutagenesis protocols in the presence or the absence of mammalian metabolic activation (S9 mixture). All flavonoids gave a dose-response relationship and induced a number of AraR mutants considered statistically significant. Their minimum mutagenic doses (MMD) differed markedly in the Ara test, covering a 400-fold range: from 4 nmol for quercetin to 1626 nmol for taxifolin. Flavonols were the strongest mutagens, with mutagenic potencies (MMD-1) representing from 27 to approximately 2% that of quercetin. Comparatively, the mutagenicities of other flavonoids represented only less than or equal to 1%. The data reported in this paper for the Ara forward mutation test suggest structural requirements for mutagenicity of bioflavonoids like those previously reported for the His reverse mutation assay: (i) flavonols with a free hydroxyl at position 3 are the strongest mutagenic flavonoids, (ii) saturation of the 2,3 double bond diminishes the mutagenic potency, and (iii) free hydroxyl groups at positions 3' and 4' influence the non-requirement for metabolic activation. The mutagenic properties of quercetin and rutin in the Ara test support the idea that these flavonols are not the major putative mutagens in complex mixtures such as wine.

Oral streptococci are described that hydrolyze the dietary glycoside rutin (CAS: 153-18-4), resulting in mutagenic activity. Bacteria that hydrolyze rutin were isolated from the mouth of each of 10 healthy volunteers. The activity was inducible, and the product was mutagenic in the Salmonella mutagenicity assay. These bacteria were present in the greatest proportion on the dorsum of the tongue where they formed 1.5% of the total cultivable microflora. The appearance of the colonies, cell morphology, and biochemical characteristics were those of Streptococcus milleri. However, rutin hydrolysis did not occur with any of 30 isolates of this species from blood of patients with bacteremia, with any of 4 stock strains, or with any of 14 strains of streptococci from the other 4 major oral species. Therefore, activation of rutin to a mutagen is not a universal function of the normal oral flora, but it can be accomplished by some strains of S. milleri.