Optimized Solvent System Research Articles

Superinsulating Polyisocyanate Based Aerogels: A Targeted Search for the Optimum Solvent System.

Polyisocyanate based aerogels combine ultralow thermal conductivities with better mechanical properties than silica aerogel, but these properties critically depend on the nature of the gelation solvent, perhaps more so than on any other parameter. Here, we present a systematic study of the relationship between the polyurethane-polyisocyanurate (PUR-PIR) aerogel microstructure, surface area, thermal conductivity, and density and the gelation solvent's Hansen solubility parameters for an industrially relevant PUR-PIR rigid foam formulation. We first investigated aerogels prepared in acetone-dimethyl sulfoxide (DMSO) blends and observed a minimum in thermal conductivity (λ) and maximum in specific surface area for an acetone:DMSO ratio of 85:15 v/v. We then prepared PUR-PIR aerogels in 32 different solvent blends, divided into three series with δDispersion, δPolarity, and δH-bonding fixed at 15.94, 11.30, and 7.48 MPa1/2, respectively, corresponding to the optimum parameters for the acetone:DMSO series. The aerogel properties display distinct dependencies on the various solubility parameters: aerogels with low thermal conductivity can be synthesized in solvents with a high δH-bonding parameter (above 7.2) and δDispersion around 16.3 MPa1/2. In contrast, the δPolarity parameter is of lesser importance. Our study highlights the importance of the gelation solvent, clarifies the influence of the different solvent properties, and provides a methodology for a targeted search across the solvent chemical space based on the Hansen solubility parameters.

An in depth study of solvent effects on yield and average molecular weight in poly(3-hexylthiophene)

Poly(3-hexylthiophene) was synthesized by chemical oxidation using FeCl3 in chloroform, dichloromethane, acetonitrile, nitromethane, nitrobenzene and mixtures of these solvents. Comparative reactions for 1 day at room temperature were carried out to investigate solvent effects. Polymer samples and the remaining reaction solutions were analyzed by MALDI-MS and LDI-MS to determine Mw and reaction completeness, respectively. Solubilities of FeCl3, FeCl2, and P3HT in each pure solvent were measured and correlated to the results. Open circuit potentials of FeCl3 and mixtures of FeCl3 and FeCl2 in pure solvents were measured and compared to the experimentally determined oxidation potential of 3-hexylthiophene. An optimized solvent system for reproducible synthesis of high Mw P3HT with quantitative yields is proposed based on MS analysis results.

HIGH-PERFORMANCE THIN LAYER CHROMATOGRAPHY (HPTLC) FINGERPRINTING PATTERN OF MANGROVE AVICENNIA MARINA

Objective: An attempt has been made to study phytoconstituents and High-Performance Thin Layer Chromatography (HPTLC) fingerprinting pattern of leaf/stem/root methanol extracts of Avicennia marina.Methods: The phytochemical screening was done by standard biochemical methods and standard optimized HPTLC densitometry determination was performed under two different energy zones [under UV-254 nm and under 540 nm after derivatization at sample size-10 µl, temperature = 25.8±0.3 °C (constant) and relative humidity = 86±1% (constant) in optimized solvent system].Results: Phytochemical analysis confirmed the presence of phytochemicals in the leaf, stem, and root of the plant. Under UV–254 nm energy range, the leaf, stem and root extract showed the presence of 8, 6 and 5 components respectively and under 540 nm energy zone after derivatization, the leaf, stem and root extract revealed the presence of 7, 5 and 5 components, respectively and specific marker components with very high concentration (under UV-254 nm; 3, 2, 2 in leaf, stem, and root respectively and under 540 nm after ASR treatment; 2, 1, 2 in leaf, stem, and root respectively) were detected among them.Conclusion: The preliminary phytochemical test results elucidated Avicennia marina leaf, stem, and root as a hug reservoir of various class of phytochemicals and metabolites. The results obtained by HPTLC fingerprinting method found to be acceptable as a quick, reliable, accurate and economical for identification and authentication of Avicennia marina mangrove plant and useful to differentiate this mangrove species from other similar mangroves, in a single TLC plate run. This serves as a biochemical marker pattern for leaf, stem and root parts of this mangrove and for its diverse phytoconstituents.

Development of gel composition and technology based on pyrimidine substance

Background: This work was conducted in the framework of quality by design project involving the production of a pharmaceutical gel. Preliminary work included the identification of the quality target product profiles from historical values for previously laboratory batches, which were used to construct a D-optimal experimental design. Fungal disease of mycoses has long been known, since the days of antiquity. Our research gel high pharmacological effect (antifungal) in comparison with the drugs “Flucytosine” and “Fucis”. Aims and Objectives: The purpose of this study is to develop the optimal composition and rational gel technology under the conventional name “Antiсandid” on the basis of the substance piperidinylethanone with an antifungal effect. Materials and Methods: Thermogravimetric analysis and rotational viscometry, which affect the process of the formation of carbopol, were taken. Based on the physicochemical properties and technological properties of the gel, an optimal solvent system is selected that corresponds to the maximum solubility of the drug substances and ensures polymer swelling. At the same time, the materials dimexide (DMSO), propylene glycol (PG), carbol-floor, and triethanol were taken into account, which improve the process of solubility and gelling. Results: The results were obtained, which, when the active substance is administered in the dissolved state, is the most therapeutic effect on the gel base. At the same time, active pharmaceutical ingredients (APIs) were dissolved in different solvents with gradual heating. The ratio of solvents DMSO-PG-water (1:4:1) at which the developed dosage form will be more structured, stable, and thixotropic is established. Conclusion: Fungal skin diseases are one of the most frequently discussed problems in various dermatological forums and in the pages of scientific journals. The relevance of this topic is determined by the high prevalence of this pathology, which, according to the literature, accounts for 37-42% of all skin diseases. The results of the studies on the study of the microbiological, physicochemical properties of APIs, and carbopol Ultrez 20 for the development of optimal composition are taken into account. It was found that the gel model with an active substance content of 3% is more effective and has high antifungal activity.

Efficient, Baseline Separation of Pyrethrins by Centrifugal Partition Chromatography

Pyrethrins are natural pesticides present in the oil extracted from the flowers of Chrysanthemum cinerariaefolium. They are potent ion-channel neurotoxins which have higher selective toxicity for insects compared to mammals. These phytochemicals have an exceptionally safe environmental profile and are an attractive natural alternative to organophosphate insecticides currently used in agriculture. The oil extract contains six pyrethrins compounds, which are structurally related esters. Isolation of reference standards for pyrethrins and their derivatives in multi-gram quantities is a prerequisite for studying toxicity and soil degradation for these natural pyrethrins. Chromatography is difficult because of the high hydrophobicity and close structural similarity. The isolated pyrethrin compounds also have poor stability because they are photosensitive. To facilitate these studies, we have developed a twostep purification process, in which the two groups were first separated by normal phase liquid chromatography on silica gel. The separation of pyrethrin, cinerin, and jasmolin within each group was achieved by centrifugal partition chromatography (CPC). We explored and successfully optimized solvent systems that were subsequently applied to achieve multi-gram scale separation. The pyrethrins I group compounds were separated using a solvent system containing heptane-methanol-acetonitrile (6:1:2, v/v) in ascending mode. The pyrethrins II group compounds were separated using a solvent system containing heptane-terbutylmethyl ether-acetonitrile-water (8:1:5:1.5, v/v) also in ascending mode. In both cases, gram quantities of individual pyrethrins with purity exceeding 99% were produced.

Preparative separation of cacao bean procyanidins by high-speed counter-current chromatography.

In this work, an efficient method for preparative separation of procyanidins from raw cacao bean extract by high-speed counter-current chromatography (HSCCC) was developed. Under the optimized solvent system of n-hexane-ethyl acetate-water (1:50:50, v/v/v) with a combination of head-tail and tail-head elution modes, various procyanidins fractions with different polymerization degrees were successfully separated. UPLC, QTOF-MS and 1H NMR analysis verified that these fractions contained monomer up to pentamer respectively. Dimeric procyanidin B2 (purity>86%) could be isolated by HSCCC in a single run. Other individual procyanidins in these fractions could be further isolated and purified by preparative HPLC. The developed HSCCC together with preparative HPLC techniques appeared to be a useful tool for large preparation of different procyanidins from cacao beans. Furthermore, by antioxidant activity assays, it was proved that both fractions and individual procyanidins possessed greater antioxidant activities compared to standard trolox. The antioxidant activities of procyanidins increase as the increase of their polymerization degree.

A New Method for the Isolation of Ergosterol and Peroxyergosterol as Active Compounds of Hygrophoropsis aurantiaca and in Vitro Antiproliferative Activity of Isolated Ergosterol Peroxide.

In the present study, ergosterol peroxide and ergosterol were isolated for the first time from fresh fruit bodies of Hygrophoropsis aurantiaca (False Chanterelle). The substances were characterized mainly by spectroscopic methods (1H-NMR, 13C-NMR, DEPT-45, DEPT-90, DEPT-135, 2D-NMR). In our study, a new specific thin layer chromatographic method was developed for determination of ergosterol and ergosterol peroxide in H. aurantiaca extract. The method is based on the separation of n-hexane extract on silica gel (Silica Gel G) TLC plates using the optimized solvent system toluene/ethyl acetate (3:1; v/v). The main advantages of the developed method are the simplicity of operation and the low cost. The in vitro study results revealed the antiproliferative properties of ergosterol peroxide against LS180 human colon cancer cells. The described effect was attributed both to altered mitochondrial activity and decreased DNA synthesis. Additionally, in the same concentration range the investigated compound was not toxic to CCD 841 CoTr human colon epithelial cells. The present study suggests that fruit bodies of H. aurantiaca have great potential for producing substances and extracts with potential applications in medicine.

HPTLC fingerprint profile of antibacterial compound produced from forest soil <i>Streptomyces</i> SFA5

<p>The present study investigates the presence of antimicrobial compounds from potent isolate <em>Streptomyces </em><em>sp. SFA5</em> from the Sabarimala forest ecosystem, Western Ghats, Kerala, India. Preliminary screening revealed <em>Streptomyces sp</em>. SFA5 isolate shows significant inhibition against the bacterial and fungal pathogens. The antibacterial compound from isolate SFA5 was produced by submerged fermentation using yeast extract malt extract broth and extracted using different solvents. Among the different solvent extracts tested, the ethyl acetate extract of SFA5 shows maximum zone of inhibition against <em>Staphylococcus aureus</em> (23mm) and<em> Bacillus cereus </em>(24mm). A simple, sensitive and accurate HPTLC method has been performed for the quantitative estimation of bioactive compounds from ethyl acetate extract of <em>Streptomyces sp.</em> SFA5. The optimized solvent system for mobile phase in HPTLC Chromatogram is toluene: ethyl acetate: methanol: acetic acid (5:3:1:0.5, v/v/v/v). Results of HPTLC finger printing of ethyl acetate extract of the strain SFA5 at UV 254 and 366 with corresponding R<sub>f </sub>values substantiate the presence of bioactive compounds.</p><p><strong>Video clip: </strong></p><p><strong></strong><a href="https://youtube.com/v/SssUrhxJ6qg">Production and extraction of bioactive compounds</a>: 5 min 43 sec</p><p> </p><p> </p>

A combination strategy for extraction and isolation of multi-component natural products by systematic two-phase solvent extraction-13C nuclear magnetic resonance pattern recognition and following conical counter-current chromatography separation: Podophyllotoxins and flavonoids from Dysosma versipellis (Hance) as examples

Despite of substantial developments of extraction and separation techniques, isolation of natural products from natural resources is still a challenging task. In this work, an efficient strategy for extraction and isolation of multi-component natural products has been successfully developed by combination of systematic two-phase liquid–liquid extraction-13C NMR pattern recognition and following conical counter-current chromatography separation. A small-scale crude sample was first distributed into 9 systematic hexane-ethyl acetate-methanol-water (HEMWat) two-phase solvent systems for determination of the optimum extraction solvents and partition coefficients of the prominent components. Then, the optimized solvent systems were used in succession to enrich the hydrophilic and lipophilic components from the large-scale crude sample. At last, the enriched components samples were further purified by a new conical counter-current chromatography (CCC). Due to the use of 13C NMR pattern recognition, the kinds and structures of major components in the solvent extracts could be predicted. Therefore, the method could collect simultaneously the partition coefficients and the structural information of components in the selected two-phase solvents. As an example, a cytotoxic extract of podophyllotoxins and flavonoids from Dysosma versipellis (Hance) was selected. After the systematic HEMWat system solvent extraction and 13C NMR pattern recognition analyses, the crude extract of D. versipellis was first degreased by the upper phase of HEMWat system (9:1:9:1, v/v), and then distributed in the two phases of the system of HEMWat (2:8:2:8, v/v) to obtain the hydrophilic lower phase extract and lipophilic upper phase extract, respectively. These extracts were further separated by conical CCC with the HEMWat systems (1:9:1:9 and 4:6:4:6, v/v). As results, total 17 cytotoxic compounds were isolated and identified. In general, whole results suggested that the strategy was very efficient for the systematic extraction and isolation of biological active components from the complex biomaterials.

Separation and purification of four flavonol diglucosides from the flower of Meconopsis integrifolia by high-speed counter-current chromatography.

Flavonoids are the main components of Meconopsis integrifolia (Maxim.) Franch, which is a traditional Tibetan medicine. However, traditional chromatography separation requires a large quantity of raw M. integrifolia and is very time consuming. Herein, we applied high-speed counter-current chromatography in the separation and purification of flavonoids from the ethanol extracts of M. integrifolia flower. Ethyl acetate/n-butanol/water (2:3:5, v/v/v) was selected as the optimum solvent system to purify the four components, namely quercetin-3-O-β-d-glucopyrannosy-(1→6)-β-d-glucopyranoside (compound 1, 60 mg), quercetin 3-O-[2'''-O-acetyl-β-d-glucopyranosyl-(1→6)-β-d-glucopyranoside (compound 2, 40 mg), quercetin 3-O-[3'''-O-acetyl-β-d-glucopyranosyl-(1→6)-β-d-glucopyranoside (compound 3, 11 mg), and quercetin 3-O-[6'''-O-acetyl-β-d-glucopyranosyl-(1→6)-β-d-glucopyranoside (compound 4, 16 mg). Among the four compounds, 3 and 4 were new acetylated flavonol diglucosides. After the high-speed counter-current chromatography separation, the purities of the four flavonol diglucosides were 98, 95, 90, and 92%, respectively. The structures of these compounds were identified by mass spectrometry and NMR spectroscopy.

Synthesis of BACE Inhibitor LY2886721. Part II. Isoxazolidines as Precursors to Chiral Aminothiazines, Selective Peptide Coupling, and a Controlled Reactive Crystallization

An efficient synthesis of LY2886721 (1) in five steps and 46% overall yield from the chiral nitrone cycloadduct 2 is presented. Minimizing formation of a des-fluoro impurity during hydrogenolysis to cleave the isoxazolidine ring and remove the benzyl chiral auxiliary was a key challenge. Installation of the aminothiazine moiety required careful stoichiometry control of the reagents BzNCS and CDI, including in situ conversion monitoring, to minimize byproduct formation. A remarkably regioselective peptide coupling afforded 1 without competing acylation at the aminothiazine nitrogen or bis-acylation. Consideration of the combined chemistry and crystallization process identified an optimal solvent system for the peptide coupling and a reactive crystallization that afforded 1 in high purity and with physical property control. A slurry milling operation near the end of the crystallization, followed by “pH cycles” to digest fines formed during milling, significantly reduced the crystal aspect ratio and provided...

Optimization of Solvent System and Polymer Concentration for Synthesis of Polyvinyl Alcohol (PVA) Fiber Using Rotary Forcespinning Technique

Rotary forcespinning is one of techniques used for fabrication of polymer fiber. In this paper optimization of several parameters for synthesis of Polyvinyl Alcohol (PVA) fiber using rotary forcespinning technique was described. In order to obtain PVA fiber with smallest diameter the optimization parameters of solvent system and polymer concentration were performed. The results show that PVA dissolved in water as a single solvent produced fiber with high wettability. A mixture of water and ethanol as a solvent system was developed with variation in ethanol content. The effects of ethanol content on fiber diameter were investigated. Rotary forcespinning using solvent with ethanol content below 30% resulted in PVA fiber with high wettability, while solvent ethanol content of more than 70% was unable to dissolve PVA completely. The effect of PVA concentration on the fiber morphology was investigated by adjusting PVA concentration in the range of 9 to 13 weight %. The diameter of the PVA fiber was uniform and could be controlled by adjusting the PVA concentration.

Preparation and characterization of polyphenylsulfone nanofibrous membranes for the potential use in liquid filtration

In the present study, polyphenylsulfone (PPSU) nanofibrous membranes were prepared and their potential use in liquid filtration was investigated. The optimum polymer concentration and solvent system for producing beadless fibers were found as 24 wt.% PPSU in N-methyl-2-pyrrolidone/dimethylformamide binary solvent system at a 30:70 volume ratio. The nanofibrous membrane was then heat treated in an oven which resulted in fusion of the fibers at their junction points and also along their length. The untreated and heat-treated membranes were characterized by water contact angle measurement, porosity determination, and tensile tests. Furthermore, performance of the untreated and heat-treated membranes was evaluated by determination of pure water flux and filtration of canned beans production wastewater. The remarkable pure water flux of 7323 L/m2 h was observed for the heat-treated membrane as a result of high porosity, improved mechanical stability, and low compaction imposed by the applied heat treatment. The untreated and heat-treated membranes showed 100% turbidity rejection, while chemical oxygen demand and total dissolved solids rejections were 30 and 29% for the untreated membrane and 27 and 25% for the heat-treated one, respectively.

Application of HPCCC, UHPLC-PDA-ESI-MS3 and HPLC-PDA methods for rapid, one-step preparative separation and quantification of rutin in Forsythia flowers

In this study, the flowers of Forsythia × intermedia, Forsythia suspensa and Forsythia ovata are presented as valued raw materials for isolation of rutin, an industrial and pharmacologically active flavonoid. An efficient strategy based on three high-performance chromatographic techniques was established to screen and purify the target compound from the plant matrices. In the first step, an UHPLC-PDA-ESI-MS3 assay documented the relatively simple phytochemical profiles of the flower extracts and led to the identification of ten polyphenols classified as caffeoyl acid derivatives, flavonoids, phenylethanoids and lignans, with rutin as the major constituent. Significant levels of rutin (20.0–57.6mg/g dw) were found in the flowers by the validated HPLC-PDA method, with the highest values observed for F. suspensa. Finally, a novel, fast, single-step HPCCC method was developed and successfully applied for the separation of rutin from the plant samples. The ethyl acetate-n-butanol-water (4:1:5, v/v/v) was selected as the optimum two-phase solvent system for both analytical and preparative normal (NP) and reversed-phase (RP) HPCCC separations. Under optimal RP-HPCCC conditions, 155 mg of the crude methanol extract was separated in a single 50min run, yielding 14.6mg of rutin with 97.2% HPLC purity and 95.9% recovery. The process efficiency of the HPCCC rutin isolation was demonstrated to be superior to the existing HSCCC methods. The results indicated the usefulness of Forsythia flowers and the developed RP-HPCCC methodology for practical and commercial applications.

TLC-bioautography linked with guess: A truely targeted active compound isolation process

In order to optimize the isolation procedure of anti-TB lead compounds, a truly targeted isolation approach was developed, which aligns (HP)TLC-bioautography with GUESS1 based countercurrent separation (CCS). (HP)TLC-bioautography was specifically developed for Mycobacterium tuberculosis, using the mc2 7000 lux ABCDE strain, while the GUESS method is used to rapidly determine the optimal CCS solvent system. Optimal CCS conditions target the separation of the inhibition zones within a range of optimal CCS partition coefficients referred to as the “CCS sweet spot”, with a corresponding TLC Rf-value ˜0.5. Hereby, the CCS solvent system is chosen on the basis of the Rf-value of the bioactive component(s) rather than the fraction as a whole. This approach accelerates the isolation process and prevents the isolation of non-active metabolites and byproducts. The new TLC-bioautography-GUESS-CCS workflow is demonstrated with the fractionation of an extract from an anti-TB active actinomycete strain. [Funding: NIH R21 AI093919 – 02] 1Friesen & Pauli, G.U.E.S.S. – A Generally Useful Estimate of Solvent Systems for CCC, Journal of Liquid Chromatography & Related Technologies, 2005, Volume 28, Issue17, 2777 – 2806 *Equal contributors

On-line two-dimensional countercurrent chromatography × high performance liquid chromatography system with a novel fragmentary dilution and turbulent mixing interface for preparation of coumarins from Cnidium monnieri

This study describes a novel on-line two-dimensional countercurrent chromatography×high performance liquid chromatography (2D CCC×HPLC) system for one-step preparative isolation of coumarins from the fruits of Cnidium monnieri. An optimal biphasic solvent system composed of n-heptane/acetone/water (31:50:19, v/v) with suitable Kd values and a higher retention of the stationary phase was chosen to separate target compounds. In order to address the solvent incompatibility problem between CCC and RP-HPLC, a novel fragmentary dilution and turbulent mixing (FD-TM) interface was successfully developed. In detail, the eluent from the first dimensional CCC column was divided into fractions to form ‘sample-dilution’ stripes in the two switching sample loops, by the dilution water from the makeup pump. Following this, a long, thin tube was applied to mix the CCC eluent with water by in-tube turbulence, to reduce the solvent effect. Each CCC fraction was alternately trapped on the two holding columns for further preparative HPLC separation. This nationally designed FD-TM strategy effectively reduced post-column pressure and allowed a higher water dilution ratio at the post end of CCC, leading to improved sample recovery and a robust 2D CCC×HPLC isolation system. As a result, in a single 2D separation run (6.5h), eight target compounds (1–8) were isolated from 0.5g crude extract of C. monnieri, in overall yields of 1.3, 2.0, 0.5, 0.5, 0.8, 1.5, 8.2, and 15.0%, with HPLC purity of 90.1, 91.1, 94.7, 99.1, 99.2, 98.2, 97.9, and 91.9%, respectively. We anticipate that this improved 2D CCC×HPLC system, based on the novel FD-TM interface, has broad application for simultaneous isolation and purification of multiple components from other complex plant-derived natural products.

Preparative HSCCC isolation of phloroglucinolysis products from grape seed polymeric proanthocyanidins as new powerful antioxidants

Polymeric proanthocyanidins isolated from a grape seed phenolic extract were hydrolysed in the presence of phloroglucinol into monomer catechins and their nucleophile derivatives. Each of the phloroglucinolysis products was successfully separated and isolated in large amount by semi-preparative HSCCC technique under the optimized conditions based on a selection of suitable solvent system. The optimized solvent system consisted of n-hexane–ethyl acetate–water (1:80:80, v/v/v) with a combination of head–tail and tail–head elution modes. By only one-step HSCCC separation, the purity of each obtained phloroglucinolysis product, including monomer catechins and their nucleophile derivatives was above 76%, verified by UPLC. The structures of these products were tentatively identified by UPLC based on their retention time and further confirmed by MS and 1H NMR analysis. Furthermore, by DPPH, ABTS and FRAP assays, it was verified that all these phloroglucinolysis products possessed strong antioxidant activities, being catechin-nucleophile derivatives more powerful than free catechins.

Separation and Purification of Gardecin from Gardenia jasminoides Ellis by High-Speed Countercurrent Chromatography

In the present study, a high-speed counter-current chromatography (HSCCC) was investigated for separation and purification of gardecin on a preparative scale. Hexane–ethyl acetate–methanol–water (0.3:1:0.3:1, v/v) was selected as the optimum solvent system to purify gardecin from a fraction obtained from HPD100 column chromatography fractionation of gardenia. After HSCCC isolation, 20.1 mg of gardecin with purity of 97.4% was obtained from 322 g of dry gardenia fruits. Chemical structure identification of this pigment was carried out by MS, 1H NMR, and 13C NMR. Additionally, antioxidant activity of gardecin in comparison with crocin-1 was investigated. The present results demonstrated that gardecin could be efficiently obtained using HSCCC from this herb and this compound features strong antioxidant activity.

Dissolution and utilization of chitosan in a 1‐carboxymethyl‐3‐methylimidazolium hydrochloride ionic salt aqueous solution

ABSTRACT1‐Carboxymethyl‐3‐methylimidazolium hydrochloride ([IMIM–COOH]Cl), a new ionic salt, is proposed as a green, promising solvent for dissolving chitosan. However, because of the optimal dosage of chitosan dissolved in [IMIM–COOH]Cl, a 12 wt % [IMIM–COOH]Cl aqueous solution was selected as an optimum solvent system for dissolving chitosan. The structures of the original and regenerated chitosan were characterized by Fourier transform infrared spectroscopy and X‐ray diffraction analysis. Scanning electron microscopy was used to visualize the morphological features of the reconstituted chitosan membranes. Meanwhile, the absorbance, tensile strength, and breaking elongation of the chitosan membranes were measured. The results reveal that 10–11 wt % was an optimal chitosan concentration for preparing membranes. Furthermore, the adsorption capacity for Cu(II) ion of the chitosan membranes was increased with the chitosan concentration decreased from 12 to 8 wt %. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41965.

Separation and purification of 9,10-dihydrophenanthrenes and bibenzyls from Pholidota chinensis by high-speed countercurrent chromatography.

Stilbenoids are the main components of leaves and stems of Pholidota chinensis. In the present investigation, high-speed counter-current chromatography was used for the separation and purification of two classes of stilbenoids, namely, bibenzyls and 9,10-dihydrophenanthrenes, on a preparative scale from whole plants of P. chinensis with different solvent systems after silica gel column chromatography fractionation. n-Hexane/ethyl acetate/methanol/water (1.2:1:1:0.8, v/v/v/v) was selected as the optimum solvent system to purify 1-(3,4,5-trimethoxyphenyl)-1',2'-ethanediol (1), coelonin (2), 3,4'-dihydroxy-5,5'-dimethoxybibenzyl (3), and 2,​7-​dihydroxy-​3,​4,​6-​trimethoxy-​9,​10-​dihydrophenanthrene (4). While 2,7-dihydroxy-3,4,6-trimethoxy-​9,​10-​dihydrophenanthrene (5), batatasin III (6), orchinol (7), and 3'-O-methylbatatasin III (8) were purified by n-hexane/ethyl acetate/methanol/water (1.6:0.8:1.2:0.4, v/v/v/v). After the high-speed counter-current chromatography isolation procedure, the purity of all compounds was over 94% assayed by ultra high performance liquid chromatography. The chemical structure identification of all compounds was carried out by mass spectrometry and (1)H and (13)C NMR spectroscopy. To the best of our knowledge, the current investigation is the first study for the separation and purification of bibenzyls and 9,10-dihydrophenanthrenes by high-speed counter-current chromatography from natural resources.