Water-soluble Flavonoids Research Articles

Antioxidant and Pro-Oxidant Properties of Carthamus Tinctorius, Hydroxy Safflor Yellow A, and Safflor Yellow A.

(1) Carthamus Tinctorius L. (safflower) is extensively used in traditional herbal medicine. (2) The aim of this study was to investigate the bioactive properties of polyphenol extracts from flowers of Carthamus Tinctorius (CT) cultivated in Italy. We also evaluated the properties of two bioactive water-soluble flavonoid compounds, hydroxy safflor yellow A (HSYA) and safflor yellow A (SYA), contained in Carthamus Tinctorius petals. (3) The total polyphenol content was 3.5 ± 0.2 g gallic acid equivalent (GAE)/100 g, flavonoids content was 330 ± 23 mg catechin equivalent (CE)/100 g in the flowers. The extract showed a high antioxidant activity evaluated by oxygen radical absorbance capacity (ORAC) and 2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assays. In addition, flower extract, SYA, and HSYA were able to reduce the susceptibility of low-density lipoprotein to copper-induced lipid peroxidation. In order to investigate the bioactive properties of flower extract, SYA, and HSYA we also studied their modulatory effect of oxidative stress on human dermal fibroblasts (HuDe) oxidized by tert-butyl hydroperoxide (t-BOOH). The CT extract at concentrations ranging from 0.01–20 μg GAE/mL of polyphenols, exerted a protective effect against t-BOOH triggered oxidative stress. At higher concentration the extract exerted a pro-oxidant effect. Similar results have been obtained using HSYA and SYA. (4) These results demonstrate a biphasic effect exerted by HSYA, SYA, and flower extracts on oxidative stress.

Improvement strategies for the oral bioavailability of poorly water-soluble flavonoids: An overview.

Although flavonoid compounds have various pharmacological applications, they generally exhibit low oral bioavailability due to their poor aqueous solubility. To address this problem, numerous promising strategies, such as the use of an absorption enhancer, structural transformation (e.g., prodrugs, glycosylation), and pharmaceutical technologies (e.g., carrier complexes, nanotechnology, cocrystals), have been developed and applied to deliver poorly water-soluble flavonoids. These formulation approaches can effectively improve the oral bioavailability of flavonoids by enhancing their solubility, dissolution rate and permeability; preventing their degradation or metabolism in the gastrointestinal tract; and/or delivering them directly to their physiological targets. This review comprehensively summarizes the viable oral delivery systems for insoluble flavonoids to date and discusses their design principles, potential advantages, possible limitations, and oral delivery efficiency, which will provide some useful clues and references to overcome the absorption barrier of these insoluble flavonoids.

Phenolic Compound Profile and Functionality of Aqueous Overripe Tempe Extracts

Tempe is a soy fermentation product and has been associated with many health benefits. It is usually consumed after 48 hours of fermentation; however extended fermentation is sometimes favoured. Since cooking involves water, it is of interest to study the health benefits of tempe water extract. In this study, we focused our study on total phenols, total flavonoids, DPPH free radical scavenging activity, cytotoxic activity, and identification of the main flavonoids. Our findings demonstrated that concentration of water-soluble flavonoids in tempe increased as fermentation time was prolonged. Fermentation for 60 hr resulted in extracts with very noticeable cytotoxic activity against MCF-7 cancer cell line (IC50 of 8.70 µg/ml). The cytotoxic activity of the extracts was fermentation time-dependent following non-linear relationship. The activity showed strong inverse correlation with total phenols and flavonoids in the extracts. LC-MS/MS data suggested that extracts from control and 24-hr fermented tempe demonstrated the highest responses for genistein, genistin, daidzein, daidzin, and glycitein, compared to those of other treatments and therefore suggested that excessive amount of the isoflavones, particularly genistein, induced cancer cell proliferation but lesser yet optimum concentration (observed at 60 hr-fermentation) contributed to otherwise effect.

Evaluation of antimicrobial activity of water-soluble flavonoids extract from Vaccinium bracteatum Thunb. leaves

Aqueous extract of Vaccinium bracteatum Thunb. leaves (VWFE) is traditionally used for food preservation in China, which is rich in flavonoids compounds. VWFE could effectively inhibit the growth of both Gram negative (Escherichia coli) and positive bacteria (Staphylococcus aureus and Bacillus subtilis), however, no inhibition effects were observed on mold and yeast. The minimum inhibitory concentration of VWFE were 2.06mg/ml, 1.03mg/ml, and 4.11mg/ml for E. coli, S. aureus and B. subtilis, respectively, which were 13%, 13%, and 26% of sodium benzoate and 23%, 11%, and 46% of potassium sorbate. Cell membrane permeability assays indicated that cell membrane disruption was one of the antibacterial mechanisms of VWFE. VWFE showed a good thermal stability. The expiration date of VWFE was 6months at 25°C, which was predicted using the accelerated aging method. This present work indicated VWFE is a potential natural antibacterial preservative.

Preparation and characterization of luteolin nanoparticles for enhance bioavailability and inhibit liver microsomal peroxidation in rats

Abstract Luteolin (LUT, 3′,4′,5,7-tetrahydroxyflavon) is a low water-soluble flavonoid with multiple biogicially activities. In this study, high water-soluble LUT nanoparticle was prepared by liquid anti-solvent precipitation and vacuum freeze-dry technology to enhance bioavailability and inhibit liver microsomal peroxidation in rats. When the concentration of LUT in the nanoparticles was 10.7 ± 0.3% (w/w), the size of LUT nanoparticles in water was successfully decreased to 127.5 ± 23.1 nm, and the amorphous state was reached. Meanwhile, the saturated solubility of LUT nanoparticles in deionized water (149.69 ± 12.6 µg) increased by 132.74 times. On the basis of the abovementioned results, LUT nanoparticles achieved excellent results in dissolution rates, lipid oxidation in vitro and bioavailability. Finally, results showed that the small particle size and amorphous state of LUT nanoparticles considerably improved their solubility in the solution medium, thereby enhancing their antioxidant ability and bioavailability.

Efficient biosynthesis, analysis, solubility and anti-bacterial activities of succinylglycosylated naringenin

A novel water-soluble flavonoid with good anti-bacterial activities, naringenin-6″-succl-7-O-glucoside (7-SGN), was synthesised. It was biotransformed from naringenin by Bacillus amyloliquefaciens FJ18 in aqueous miscible organic media, and characterised by LC-MS and NMR analysis. The solubility of 7-SGN in water was approximately 102 times higher than that of naringenin. These results demonstrated that both the water solubility and the anti-bacterial activity of 7-SGN were significantly improved.

Tailoring Properties of Acidic Types of Natural Deep Eutectics Solvents (NADES): Enhanced Solubility of Curcuminoids from Curcuma zeodaria

Recently Natural Deep Eutectic Solvents (NADES) show their potential as a promising green solvents at 21th century for extraction of natural products. Rutin, a poorly water soluble flavonoid, was reported better solubilized in NADES than in water as well as a paclitaxel and ginkgolide B, a completely water-insoluble compound. In case of curcuminoids, phenolic compounds from powder of Curcuma Zeodaria shown better solubilized in acidic type of NADES such malic acid-sucrose-water (MAS-H2O = 1:1:11, mole ratio) and citric acid-sucrose-water (CAS-H2O = 1:2:15, mole ratio) compare to water and ethanol. Indicating that NADES, a water-based solvent, appropriate for extracting curcuminoids. However, the inherent high viscosity of NADES hamper the process extraction. Lowering the viscosity, water content of NADES is varied, adding a certain amount of water up to 60% of water content. All the varied water content of both CAS-H2O and MAS-H2O were successfully extracted curcuminoids. Yielded 0.06-0.16 mg curcuminoids/g dry weight. However, 60% of water content of both CAS-H2O and MAS-H2O gave more or less similar value of curcuminoids to CAS-H2O (20% of water) and MAS-H2O (30% of water). Curcuminoids is more stable in CAS-H2O compare to MAS-H2O for 96 h of time duration.

Anticancer effects of morin-7-sulphate sodium, a flavonoid derivative, in mouse melanoma cells.

Increasing evidence supports the anticancer effects of morin in vitro and in vivo. However, the role of morin-7-sulphate sodium (NaMoS), a water-soluble flavonoid derivative synthesized from morin remains unclear. The present study investigated the tumor suppression by NaMoS in mouse melanoma cells. We synthesized the flavonoid derivative morin-7-sulphate sodium according to the method described for quercetin-sulphate derivative, and further isolated, purified and identified the compound. Cell proliferation in vitro was assessed using a CCK-8 assay. The wound healing assay was performed to evaluate cell motility, and flow cytometry was used to detect cellular apoptosis. Protein levels of vimentin, matrix metalloproteinase 9 (MMP9), phosphorylation of Akt1/2/3 (p-Akt1/2/3), extracellular signal-regulated kinase 1/2 (p-ERK1/2) and Caspase3 in B16F10 cells were detected by immunohistochemistry and Western blot. The results suggest that cell proliferation was markedly decreased in NaMoS-treated groups (1, 10, 25, 50, 100, 500, 1000μM) in a dose-dependent manner compared with the Control group and the IC50 was 221.67μM at 48h. NaMoS at 200μM concentration significantly inhibited the invasion and promoted apoptosis of B16F10 cells. Moreover, protein level of Caspase3 increased significantly in B16F10 cells treated by NaMoS. Immunohistochemistry and Western blot further confirmed that NaMoS decreased the expression of vimentin, MMP9, p-Akt1/2/3 and p-ERK1/2 in B16F10 cells. This study provides robust evidence that NaMoS, a water-soluble flavonoid, manifests anticancer properties and may act as a signal transduction inhibitor in melanoma cells.

A new mechanism for increasing the oral bioavailability of scutellarin with Cremophor EL: Activation of MRP3 with concurrent inhibition of MRP2 and BCRP

Efflux transporters are extensively distributed and expressed in the intestinal epithelium and contribute to the low oral bioavailability of flavonoids and flavonoid glucuronides by pumping these compounds back into intestinal lumen. Our previous study has shown the inhibitory effect of Cremophor EL, a non-ionic surfactant, on efflux transporter multidrug resistance-associated protein (MRP) 2. In the current study, by using membranes overexpressing several common ATP-binding cassette (ABC) transporters including P-glycoprotein (P-gp), MRP1, MRP2, MRP3 and breast cancer resistance protein (BCRP), scutellarin, a poorly water-soluble flavonoid, was identified as the substrate of MPR2, MRP3 and BCRP. The effects of Cremophor EL on the transmembrane transportation of scutellarin by MRP2, BCRP, and MRP3 were investigated with inside-out Sf9 vesicles. Results showed that at nontoxic concentrations, Cremophor EL enhanced the transportation of scutellarin by MRP3 and inhibited the efflux transportation of scutellarin by MRP2 and BCRP concurrently. The relations between Cremophor EL and these transporters were explored using MDCK II-MRP2, MDCK II-BCRP, and MDCK II-MRP3 cell models. Compared with the control group, 5μg/ml Cremophor EL decreased the Papp(BL-AP) of scutellarin in MDCK II-MRP2 cell monolayers by >4 fold (from 13.57±0.76×10−7 to 2.90±0.14×10−7cm/s), and the Papp(BL-AP) in MDCK II-BCRP cell monolayers decreased from 9.12±0.15×10−7 to 6.34±0.08×10−7cm/s. On MDCK II-MRP3 cell monolayers, 5μg/ml Cremophor EL increased the Papp(AP-BL) of scutellarin by 3.5 fold (from 7.88±0.43×10−7 to 2.79±1.61×10−6cm/s), and caused an over 5-fold increase in Papp(AP-BL)/Papp(BL-AP). These findings suggested that Cremophor EL possesses the potent ability of inhibiting MRP2 and BCRP, as well as activating MRP3 effectively. In vivo pharmacokinetic research in rats further confirmed the improvement of oral absorption of scutellarin by Cremophor EL. In summary, our present study has identified a new mechanism for increasing the oral absorption and bioavailability of poorly absorbed drugs in which Cremophor EL increased MRP3 mediated transport but reduced MRP2 and BCRP mediated efflux concurrently, thereby enhancing the entry of drugs from enterocytes into the blood circulation.

Combined process of reaction, extraction, and purification of lutein in marigold flower by isopropanol–KOH aqueous two-phase system

ABSTRACTThis paper established a viable process for the simultaneous reaction, extraction, and primary purification of lutein in marigold flower by the isopropanol–KOH aqueous two-phase system (ATPS). In this process, the liposoluble lutein esters were translated into water-soluble lutein by saponification reaction in ATPS and distributed to the top phase. Meanwhile, the water-soluble flavonoids in marigold were also extracted and distributed to the bottom phase. The concentrations of phase-forming isopropanol and KOH, the added mass of marigold flower powder, temperature, and time were investigated to evaluate their effects on the extraction and partition behaviour of lutein and flavoniods in ATPS. Under the optimal conditions (38% isopropanol, 18% KOH, 0.05 g of marigold flower powder, 500°C and 1.5 h extraction time), the leaching efficiency, extraction efficiency, and partition coefficient of lutein were 84.64%, 86.73%, and 5.115, respectively, and at this point, the saponification rate of lutein reached 93.98%. Meanwhile, the leaching efficiency, extraction efficiency, and partition coefficient of flavoniods were 96.68%, 78.31%, and 0.2167, respectively. This method shows the superiority to the conventional one for it can not only efficiently extract lutein in marigold flower, but also achieve a high saponification rate of lutein esters and simultaneously separate two major pigments.

Radio protective effects of the Ayurvedic medicinal plant Ocimum sanctum Linn. (Holy Basil): A memoir.

The use of compounds which can selectively protect normal tissues against radiation injury is of immense use because in addition to it protecting the normal tissue, will also permits use of higher doses of radiation to obtain better cancer control and possible cure. However, most of the radio protective compounds investigated possess inadequate clinical application principally due to their inherent systemic toxicity at their optimal protective concentrations. Plants commonly used as medicinal and dietary agents have recently been the focus of attention and studies have shown that Ocimum sanctum Linn. commonly known as the Holy Basil and its water soluble flavonoids, orientin and vicenin protects experimental animals against the radiation-induced sickness and mortality at nontoxic concentrations. Studies with tumor bearing mice have also shown that both Tulsi extract and its flavonoids selectively protect the normal tissues against the tumoricidal effects of radiation. Preclinical studies have also shown that the aqueous extract of the Tulsi leaves; its flavanoids orientin and vicenin, and eugenol, the principal nonpolar constituent present in Tulsi prevent radiation-induced clastogenesis. Mechanistic studies have indicated that free radical scavenging, antioxidant, metal chelating and anti-inflammatory effects may contribute toward the observed protection. In addition, clinical studies with a small number of patients have shown that Tulsi was effective as a radio protective agent. This review summarizes the results related to the radio protective properties of Tulsi and its phytochemicals and also emphasizes the aspects that warrant future research to establish its use as a radio protective agent.

Determination of six C-Glycoside flavones and antitumor activity of water-soluble total flavonoids from Isodon lophanthoides var. gerardianus

This research established an HPLC method for determination of six C-Glycoside flavones of warer-soluble total flavonoids from Isodon lophanthoides var. gerardianus (Benth.) H. Hara, and studied the antitumor activity of the warer-soluble total flavonoids. The HPLC system consisted of Kromasil 100-5 C18 (4.6 mm x 250 mm, 5 microm) column and a solution system of methanol, acetonitrile and 0.5% formic acid gradient elution at a flow rate of 0. 8 mL x min(-1) and the wavelength of detector was at 334 nm. The column temperature was 25 degrees C. The antitumor activity of water-soluble flavonoids was assayed using HepG2 cell as the tested cell. The linear ranges of vicenin II, vicenin III, isoschaftoside, schaftoside, vitexin, 6, 8-di-C-a-L-arabinosylapigenin were 0.25-2.53, 0.12-1.20, 0.37-3.69, 0.16-1.63, 0.19-1.92, 0.14-1.42 microg, respectively. The average recoveries (n = 6) were 99.6% (RSD 0.87%), 100.2% (RSD 2.0%), 99.6% (RSD 1.8%), 97.9% (RSD 1.5%), 98.8% (RSD 1.2%), 98.6% (RSD 1.2%), respectively. After exposure in 24, 48, 72 h, the total flavonoids showed inhibitory effect on the proliferation of HepG2 cells with IC50 as the evaluation index, the IC50 values of 1.89, 1.71, 1.51 g x L(-1), respectively. The method is quick, simple and accurate with good re- producibility, and can be used for determination of vicenin II, vicenin III, isoschaftoside, schaftoside, vitexin, 6, 8-di-C-a-L-arabino- sylapigenin in the warer-soluble total flavonoids from L lophanthoides var. gerardianus. The warer-soluble total flavonoids from L lophanthoides have inhibitory effect on the proliferation of HepG2 cells.

Anthocyanins During Baking: Their Degradation Kinetics and Impacts on Color and Antioxidant Capacity of Bread

Anthocyanins, a subgroup of water-soluble flavonoids which occur naturally in the plant kingdom, are responsible for many of the colors observed in nature. Studies have demonstrated that anthocyanins can help in the prevention of cardiovascular and neurological diseases, cancer, and inflammation (Konczak and Zhang in J Biomed Biotechnol 5:239–240, 2004).

Measurement and correlation of solubility of diosmin in four pure solvents and β-cyclodextrin solution at 298.15 K to 333.15 K

The aim of present study was to measure and correlate the solubility of poorly water-soluble flavonoid diosmin in water, ethanol, isopropyl alcohol (IPA), polyethylene glycol-400 (PEG-400) and β-cyclodextrin (β-CD) aqueous solution (0.02mol·L−1). The solubility of diosmin was measured using the shake flask method from (298.15 to 333.15)K at atmospheric pressure. The experimental solubilities of diosmin were regressed by the modified Apelblat model with a relative deviation in the range of 0.048% to 5.940%. The correlation coefficients were observed in the range of 0.9957 to 0.9995. The solubility of diosmin was found to be increased with temperature in all sample matrices investigated. The mole fraction solubility of diosmin was found to be higher in β-CD aqueous solution and PEG-400 as compared to water, ethanol and IPA. Based on solubility data of present study, diosmin was considered as practically insoluble in water, insoluble in ethanol & IPA and soluble in PEG-400 and β-CD aqueous solution.

The Antioxidant Flavonoids, Orientin and Vicenin Enhance Repair of Radiation-Induced Damage

A B S T R A C T Orientin (Ot) and vicenin (Vc), two water soluble flavonoids isolated from the Indian Holy Basil, are potent radioprotectants, but the mechanisms of protection are not fully understood. In the present study, we investigated the effects of these flavonoids as antioxidants in chemical systems and plasmid DNA and radioprotectants in bacterial and mammalian cells. The radical scavenging activities of Ot and Vc were assessed in two chemical systems, dipehnylpicrylhydrazyl (DPPH) and 2,2´-azino-bis(3-thylbenz-thiazoline-6sulfonic acid) (ABTS) by estimating absorbance at 517 and 734 nm, respectively. Protection by the flavonoids against H 2 O 2 (30 mM) damage to plasmid pGEM7Zf was assessed by DNA electrophoresis. Effect of flavonoid pre-treatment on survival of irradiated (30-150 Gy γ-rays) repair proficient (AB1157) and repair deficient (MD2130) E.coli cells was assayed. Furthermore, induction and repair of DNA damage to 4 Gy irradiated mouse splenocytes was analyzed using the comet assay. Ot and Vc significantly scavenged DPPH and ABTS. Both flavonoids protected plasmid pGEM-7Zf in the nicked circular form following H 2 O 2 treatment. Pretreatment with 200 µM of either flavonoid significantly increased clonogenic survival of repair proficient cells at all radiation (RT) doses; in repair deficient strain, protection was significant at the lower RT doses (30 and 50 Gy, p<0.01). Ot and Vc significantly reduced 4 Gy-induced DNA damage and allowed for faster repair of ex-vivo irradiated mouse splenocytes.

Human plasma protein binding of water soluble flavonoids extracted from citrus peels

The human plasma protein binding of water soluble flavonoids in the peels of five spices of citrus fruits was studied by ultrafiltration combined with HPLC. The flavonoids were extracted separately by hot and cold water, and higher total flavonoid contents were detected in the former extracts than the latter ones. All the extracts show significant scavenging abilities to both ABTS and DPPH free radicals, which indicates the health benefits of the water extracts of citrus fruits peels. For DPPH radical, the IC50 values of hot extract follow as Navel orange (NO)≈Mandarin orange (MO)< Lemon (LE)< Lo tangerine (LO)< Pomelo (PO), while the rank is NO< PO<LE≈MO<LO for ABTS radical. The HPLC results reveal that the kinds and contents of the flavonoids detected in the extracts are different among the species. MO extract has the most neohesperidin dihydrochalcone of 118.76 μmol/L and quercetrin of 211.81 μmol/L of which are much more than the rest extracts. Pomelo extract has the most plentiful flavonoids of naringin with a concentration of 303.28 μmol/L. The high contents of myricetrin and dihydromyricetin which both are potent free radical scavengers may explain the highest free radical scavenging activity of the NO extract. The plasma binding rates decrease with the increasing concentrations of flavonoids, and the flavonoids having plenty hydroxyl groups on both A ring and B ring of the molecular skeleton have relative higher plasma binding rates. In addition, the plasma binding rates of flavonoids with saturated C3–C4 bond decrease significantly with the increasing concentrations.

The novel water soluble flavonoid dihydroquercetin monosuccinate: A cyclic voltammetry

A novel water soluble antioxidant, dihydroquercetin monosuccinate electrochemical transformations have been studied on the graphite electrode in a wide range of pH. In contrast to acidic solutions, in basic media dihydroquercetin monosuccinate redox transformations have a weak diffusion control, and occur in the close to electrode surface layer. The number of protons transferred per one electron for different conditions has been elucidated.

Biochemistry and biosynthesis of insect pigments

The functional role and commercial importance of insect pigments have been studied for well over a century. They are classified into those synthesized by insects, which include anthraquinones, aphins, pterins, tetrapyrroles, ommochromes, melanins and papiliochromes, and those sequestered from their host plants, the antioxidative carotenoids and water-soluble flavonoids. They can also be categorized into those that are produced by cyclization of linear precursors, e.g. anthraquinones, aphins and tetrapyrroles and those derived from cyclic precursors such as pterins, ommochromes, melanins and anthocyanins. Anthraquinones and aphins are derived by cyclization of linear polyketides via successive condensation of simple carboxylic acid metabolites and occur in two major Superfamilies of Hemiptera, the Coccoidea and Aphidoidae, respectively. Ommochromes, tetrapyrroles and melanins are derived from different amino acid precursors, tryptophan, glycine and tyrosine, respectively. Apart from providing body colouration, ommochromes are visual pigments, melanins act as a protectant against UV and tetrapyrroles facilitate oxygen transport to cells. Papiliochromes are synthesized using both, the essential amino acids tyrosine and tryptophan. Pterins are derived from guanosine triphosphate (GTP) and are also present in ommatidia of eyes. The sequestered pigments, anthocyanins and carotenoids, are synthesized from phenylalanine and by condensation of two isoprene units, respectively, in plants. The biosyntheses of chemochromes in insects are governed by a complex set of enzymes, pathways and genetics. This review provides a comprehensive understanding of the molecules that are not only responsible for the striking colours but also provide functional benefits for insects. The commercially important pigments are also discussed.

β-cyclodextrin assistant flavonoid glycosides enzymatic hydrolysis

Background:The content of icaritin and genistein in herba is very low, preparation with relatively large quantities is an important issue for extensive pharmacological studies.Objective:This study focuses on preparing and enzymic hydrolysis of flavonoid glycosides /β-cyclodextrin inclusion complex to increase the hydrolysis rate.Materials and Methods:The physical property of newly prepared inclusion complex was tested by differential scanning calorimetry (DSC). The conditions of enzymatic hydrolysis were optimized for the bioconversion of flavonoid glycosides /β-cyclodextrin inclusion complex by mono-factor experimental design. The experiments are using the icariin and genistein as the model drugs.Results:The solubility of icariin and genistein were increased almost 17 times from 29.2 μg/ml to 513.5 μg/ml at 60°C and 28 times from 7.78 μg/ml to 221.46 μg/ml at 50°C, respectively, demonstrating that the inclusion complex could significantly increase the solubility of flavonoid glycosides. Under the optimal conditions, the reaction time of icariin and genistin decreased by 68% and 145%, when compared with that without β-CD inclusion. By using this enzymatic condition, 473 mg icaritin (with the purity of 99.34%) and 567 mg genistein(with the purity of 99.46%), which was finally determined by melt point, ESI-MS, UV, IR, 1H NMR and 13C NMR, was obtained eventually by transforming the inclusion complex(contains 1.0 g substrates).Conclusion:This study can clearly indicate a new attempt to improve the speed of enzyme-hydrolysis of poorly water-soluble flavonoid glycosides and find a more superior condition which is used to prepare icaritin and genistein.

Solubilities of quercetin in three β‐cyclodextrin derivative solutions at different temperatures

The solubilities of quercetin, a slightly water-soluble flavonoid drug, as a function of different concentrations of cyclodextrins (hydroxypropyl-β-cyclodextrin, HP-βCD; sulfobutyl ether-β-cyclodextrin, SBE-βCD; and methylated-β-cyclodextrin, M-βCD) in Tris–HCl buffer solutions of pH7.4 at different temperatures (from 298.15K to 313.15K) were investigated. The results showed a linear increase in the solubility of quercetin with the increasing molality of CDs at the same temperature. The solubility of quercetin determined with the three CDs followed the rank order SBE-βCD>HP-βCD>M-βCD. Solubilities of quercetin increase in the three CD solutions with an increase in temperature. The experimental solubility data were well-correlated as a function of molalities of CDs and temperature.