Extraction of fatty acids from grape seed by superheated hexane

Superheated hexane extraction has been tested for obtaining fatty acids from grape seed and compared with conventional Soxhlet and hot hexane extractions. Seeds from grape residues from a winery were dried for 46 h at 105 °C, milled and sieved by particle size (d < 0.42 mm, 0.42 < d < 0.84 mm and d > 0.84 mm). An optimization study of influential variables on superheated hexane extraction (namely extraction time, temperature, pression, particle size and sample amount) was carried out by a multivariate approach. All the extracts were concentrated in a rotary evaporator and dried by adding 1 g of Na₂SO₄. Then, 2 ml of the dried extract were subjected to reaction with 1 ml of a 0.5 M solution of sodium methylate in methanol to obtain fatty acid methyl esters (FAMEs). After derivatization, FAMEs were quantified by GC-FID. The results show that the optimal conditions for superheated hexane extraction are: time extraction, 10 min; temperature, 80 °C; pressure, 40 bar; particle size, d < 0.42 mm; amount of sample, 0.4 g. Under these conditions, around 84% of the fatty acids (out of the amount obtained by Soxhlet extraction) is extracted. Comparison with Soxhlet and hot hexane extractions showed that the percentages of FAMEs are similar in all the extracts and they agree with the data in the bibliography.     

An Extraction Method for Obtaining the Maximum Non-Anthocyanin Phenolics from Grape Berry Skins

To obtain maximum non-anthocyanin phenolics from grape skins, various extraction conditions were evaluated according to the amounts of 8 non-anthocyanin phenolics. The result showed that the optimal extraction was performed in ethyl acetate solution at 25°C, with liquid/solid ratio of 10:1 (ml/g) and for 30 min. On this basis, the non-anthocyanin extracts from two red and two white grape cultivars were analyzed using high performance liquid chromatography coupled with tandem mass spectrometry (HPLC- MS/MS), and twenty-four compounds were qualified and simultaneously quantified, which indicated that the present extraction method was suitable for the study of non-anthocyanin in grape skins.     

Separation of eight selected flavan-3-ols on cellulose thin-layer chromatographic plates

The potential of microcristaline cellulose as sorbent in the separation of eight compounds: (+)-catechin (C), (-)-epicatechin (EC), (-)-gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), (-)-epigallocatechin gallate (EGCg), procyanidin B1 and procyanidin B2 was studied. Cellulose HPTLC plates prewashed in water (not necessary, when water was used as developing solvent) and dried with a hair dryer, bandwise application and development in horizontal developing chamber (sandwich configuration) gave the best results. Detection was performed using vanillin-H3PO4 reagent. Four new developing solvent systems were proposed: water, 1-propanol-water (20:80, v/v), 1-propanol-water-acetic acid (4:2:1, v/v) and 1-propanol-water-acetic acid (20:80:1, v/v), and at least two of them were needed for the differentiation between all eight compounds. Surprisingly, water enabled the separation of epimers C from EC and GC from EGC, as well as the dimers procianidin B1 and B2. Additionally, C, EGC, B1 and B2 were separated from all the other compounds. The best choice for developing solvent is given for each of the studied compounds. The best separation of the five main catechins (EC, GC, EGC, ECg, EGCg) present in green tea extract was achieved using 1-propanol-water-acetic acid (20:80:1, v/v). The chromatograms of oak bark extract developed in solvents with higher water content (1-propanol-water (1:4, v/v) and 1-propanol-water-acetic acid (20:80:1, v/v)) showed less bands than chromatograms developed in solvents with higher organic modifier content (e.g. 1-propanol-water-acetic acid (4:2:1, v/v)). It was proved that such behavior was due to the presence of procyanidins beside the main component catechin.     

Antioxidant activity of grape skin aqueous extracts from pressurized hot water extraction combined with electron paramagnetic resonance spectroscopy

Pressurized hot water extraction (PHWE) was employed to prepare extracts from dried grape skin of two wine grape varieties (St. Laurent and Alibernet) at various temperatures (from 40 up to 120 °C) and amounts of sample (0.5, 1.0 and 1.5 g). To assess the antioxidant activity of the extracts, electron paramagnetic resonance (EPR) spectroscopy was applied involving DPPH and ABTS⁺ assays. Other extract characteristics including HPLC profile of anthocyanins and total phenolic compound content were obtained as well. PHWE has also been compared with earlier results of extractions of the same grape skin samples with compressed methanol and compressed ethanol under the conditions of pressurized fluid extraction (PFE). From this comparison, PHWE emerges as the more benign and efficient extraction method to recover valuable phenolic antioxidants from grape skins for the prospective use in functional food supplements.     

Anomalous electrophoretic behavior of a chitinase isoform from grape berries and wine in glycol chitin-containing sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels

An anomalous electrophoretic behavior of a chitinase isoform present in both grape (Vitis vinifera L.) berries and wine was observed in glycol chitin-containing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels. A progressive shift of the relative molecular mass M(r) of the enzyme (from approximately 30,500 up to approximately 57,700) with increasing glycol chitin concentration in the gels up to 0.1% was revealed when samples were electrophoresed under nonreducing conditions, whereas the presence of glycol chitin had no effects when samples were reduced before SDS-PAGE separation. The M(r) of other grape and wine chitinase isoforms as well as that of the chitinase from pomegranate (Punica granatum L.) fruit was unaffected by the presence of the substrate in the gel under both reducing and nonreducing conditions. Since the enzymes were inactive during the electrophoretic separation, it is likely that the retarding effect of glycol chitin observed specifically for the unreduced chitinase band from grape and wine was due to an interaction between the substrate and a chitin-binding domain different from the catalytic site, such as that typical of class I and class IV chitinases.     

多取代1,4-戊二烯-3-醇的合成及其在螺环四氢喹啉衍生物合成中的应用

以取代邻氨基苯甲酸为起始原料,经6步反应合成了7个多取代1,4-戊二烯-3-醇（7a~7g）;以7a~7g为原料,5 mol%FeCl₃为催化剂,CH₂Cl₂为溶剂,于室温反应合成了7个螺环四氢喹啉衍生物（8a~8g）,其结构经¹H NMR, ¹³C NMR, IR和HR-MS(ESI)表征。采用X-射线单晶衍射研究了8d的晶体结构。结果表明：8d的晶胞参数a=14.001(3) , b=12.335(2) , c=11.587(3) , α=90°, β=95.497(2)°, γ=90°, V=1 991.9(7) ³, Z=4, μ=0.182 mm^-1, F(000)=816.0, R[F²>2σ(F²)］=0.053 7, wR(F²)=0.132 5。     

Supercritical fluid extraction and HPLC determination of relevant polyphenolic compounds in grape skin

The polyphenols determined are: (+)-catechin, (-)-epicatechin, rutin, quercetin and trans-resveratrol. Suitable conditions of supercritical fluid extraction were established using ethanol as a modifier of the polarity solvent (supercritical carbon dioxide). Final extraction conditions were: 20% v/v ethanol, 60degreesC, 250 bars and flow rate 2 mL/min. Static step time and dynamic step time were established using a selected grape skin sample. The extract was collected in water; the more polar polyphenols ((+)-catechin and (-)-epicatechin) remain in solution but rutin, quercetin and trans-resveratrol precipitate in this medium, thereby the solution of the extracted polyphenols was filtered. (+)-Catechin and (-)-epicatechin were determined in the liquid fraction, while the solid fraction, containing rutin, quercetin and trans-resveratrol, was solved with ethanol/H20 (40:60). HPLC determination was carried out at C18 stationary phase, with ethanol/water/acetic acid as mobile phases and UV-visible diode array detection. Due to the significant differences between the polarity of the polyphenols, two different mobile phases were used. An ethanol/water/acetic acid (5:93:2) mobile phase was used to determine (+)-catechin (280 nm) and (-)-epicatechin (280 nm). On the other hand, rutin (254 nm), quercetin (254 nm) and trans-resveratrol (306 nm) were resolved using ethanol/water/acetic acid (40:58:2) as mobile phase. Instrumental parameters were optimised and analytical parameters obtained. The analytical method was validated and applied to five different varieties of Vitis vinifera from the geographical area of Valencia.     

Syntheses of tetrahydropyridin-3-ol and tetrahydroazepin-3-ol from a chiral aziridine-2-carboxylate

A method for the stereoselective preparation of 1,2,3,6-tetrahydropyridin-3-ols and 2,3,4,7-tetrahydro-1H-azepin-3-ols, potentially versatile intermediates in the asymmetric synthesis of various piperidine alkaloids and azasugars, has been developed. The routes start with a readily available optically pure aziridine-2-carboxylate. The design strategy relies on four key transformations involving (1) stereoselective reduction of an acyl-aziridine intermediate derived from the aziridine-2-carboxylate, (2) regioselective aziridine ring opening, (3) N-allylation, and (4) ring-closing metathesis. The method developed in this investigation provides ready access to stereochemically defined and highly functionalized 3-hydroxy-substituted tetrahydropyridines and tetrahydroazepines.     

Synthesis of Drim-9(11)-en-8α- and -8β-ols from Drimenol

Drim-9(11)-en-8α-ol and drim-9(11)-en-8β-ol were synthesized in six steps from drimenol. Drimenol was oxidized by P₂O₅ and DMSO to drimenal, which isomerized with p-TsOH into isodrimenal. Isodrimenal was reduced by NaBH₄ into isodrimenol, epoxidation of which by m-CPBA gave a mixture (3.4:1) of α- and β-epoxyisodrimenols. These reacted with tosyl chloride in Py to give a mixture of α- and β-epoxyisodrimenol tosylates. Treatment of the tosylate mixture with KI and then Ph₃P produced a mixture of drim-9(11)-en-8α- and -8β-ols that was separated chromatographically. The overall yield was ∼26%.__________Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 152–155, March–April, 2005.     

Application of Fourier transform infrared spectroscopy and orthogonal projections to latent structures/partial least squares regression for estimation of procyanidins average degree of polymerisation

Fourier transform infrared (FTIR) spectroscopy has being emphasised as a widespread technique in the quick assess of food components. In this work, procyanidins were extracted with methanol and acetone/water from the seeds of white and red grape varieties. A fractionation by graded methanol/chloroform precipitations allowed to obtain 26 samples that were characterised using thiolysis as pre-treatment followed by HPLC-UV and MS detection. The average degree of polymerisation (DPn) of the procyanidins in the samples ranged from 2 to 11 flavan-3-ol residues. FTIR spectroscopy within the wavenumbers region of 1800-700 cm⁻¹ allowed to build a partial least squares (PLS1) regression model with 8 latent variables (LVs) for the estimation of the DPn, giving a RMSECV of 11.7%, with a R² of 0.91 and a RMSEP of 2.58. The application of orthogonal projection to latent structures (O-PLS1) clarifies the interpretation of the regression model vectors. Moreover, the O-PLS procedure has removed 88% of non-correlated variations with the DPn, allowing to relate the increase of the absorbance peaks at 1203 and 1099 cm⁻¹ with the increase of the DPn due to the higher proportion of substitutions in the aromatic ring of the polymerised procyanidin molecules.     

Separation and purification of both tea seed polysaccharide and saponin from camellia cake extract using macroporous resin

A novel method to separate and purify tea seed polysaccharide and tea seed saponin from camellia cake extract by macroporous resin was developed. Among four kinds of resins (AB‐8, NKA‐9, XDA‐6, and D4020) tested, AB‐8 macroporous resin possessed optimal separating capacity for the two substances and thus was selected for the separation, in which deionized water was used to elute tea seed polysaccharide, 0.25% NaOH solution to remove the undesired pigments, and 90% ethanol to elute tea seed saponin. Further dynamic adsorption/desorption experiments on AB‐8 resin‐based column chromatography were conducted to obtain the optimal parameters. Under optimal dynamic adsorption and desorption conditions, 18.7 and 11.8% yield of tea seed polysaccharide and tea seed saponin were obtained with purities of 89.2 and 96.0%, respectively. The developed method provides a potential approach for the large‐scale production of tea seed polysaccharide and tea seed saponin from camellia cake.     

高速逆流色谱结合制备液相色谱法分离制备葡萄籽中的多酚

采用高速逆流色谱结合制备液相色谱法从葡萄籽乙醇提取物中分离得到了8种多酚。高速逆流色谱以上相为固定相,下相为流动相,主机转速为900 r/min,流速为2 mL/min,分离温度为25℃,检测波长为280 nm,利用正向和反向洗脱相结合的模式,在正丁醇-乙酸乙酯-水（1∶14∶15,v/v/v）和正己烷-乙酸乙酯-水（1∶10∶10,v/v/v）溶剂系统下从葡萄籽提取物中分离得到了5种多酚。原花青素B₁、原花青素B₂、没食子酸、表儿茶素没食子酸酯和儿茶素的纯度分别为98.5%、97.2%、98.3%、98.9%和96.7%。利用制备液相色谱法对高速逆流色谱分离成分进一步分离纯化,获得了表儿茶素、表没食子儿茶素没食子酸酯和没食子儿茶素没食子酸酯,纯度分别99.2%、99.3%和99.2%。该方法单次制备量均达到毫克级,简便、快速、分离纯度高,适合于葡萄籽中多酚的分离制备。     

双金属改性MCM-41催化甲醛与异丁烯Prins缩合反应

通过研磨法制备了一系列不同金属负载的MCM-41催化剂,考察了单一金属及双金属负载催化剂对甲醛与异丁烯Prins缩合制备3-甲基-3-丁烯-1-醇(MBO)反应性能的影响,筛选出最佳的双金属Cu-Al负载催化剂.利用XRD、 NH_3-TPD、 N_2吸附、 UV-vis等表征手段对双金属改性前后催化剂的结构和酸性进行了深入分析,探究了其物质的量比例和协同作用对Prins反应性能的影响.结果表明,在温度200℃, n(异丁烯)/n(甲醛)=7,反应4 h的适宜条件下, Cu-Al(1∶1)/MCM-41对甲醛的转化率为100%, MBO产率高达98%,高于单一金属负载的催化剂. NH_3-TPD表征发现Cu-Al双金属负载催化剂具有适当的酸量和适宜的酸强度,可以提高MBO的产率.Cu-Al(1∶1)/MCM-41催化剂具有一定的再生性能,连续3次再生后催化剂的比表面积和孔容明显降低,催化剂活性中心聚集导致酸量尤其是中强酸和强酸量减少是反应活性下降的主要原因.     

Asymmetric reduction of prochiral ketones using in situ generated oxazaborolidine derived from (1S,2S,3R,4R)-3-amino-7,7-dimethoxynorbornan-2-ol. An efficient synthesis of enantiopure (R)-tomoxetine

Catalytic asymmetric reduction of prochiral ketones was examined in the presence of chiral oxazaborolidine catalyst 2 prepared in situ from (1S,2S,3R,4R)-3-amino-7,7-dimethoxynorbornan-2-ol (1). The optically active secondary alcohols were generally obtained in moderate to high enantiomeric excesses (ee 43-95%) and good yields (75-94%), except for ketones bearing electron-withdrawing groups. The methodology was applied to the synthesis of enantiopure (R)-tomoxetine, a potent anti-depressant drug.     

Efficient Room-Temperature Synthesis and Antimicrobial Study of Novel 2-Aroylbenzofuran-3-ols from Substituted Methyl Salicylates and Phenacyl Bromides

The article describes a convenient and efficient synthetic route for the construction of 2-aroylbenzofuran-3-ols from readily available diverse methyl salicylates and phenacyl bromides using K₂CO₃ as catalyst in dimethylformamide as solvent at room temperature. The reaction involves two steps, which occur in quick succession within 1 h to deliver the product with reasonably high yields. All the synthesized 2-aroylbenzofuran-3-ols (4a–u) were subjected for their antimicrobial studies, and some of these have shown prominent activity.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

A new methylene bisflavan-3-ol from the branches and leaves of Potentilla fruticosa

Abstract

Dasiphora fruticosa L. (Rosaceae), also known as Potentilla fruticosa L. (syn.), is a hardy deciduous shrub widely distributed in the north temperate regions of the world. Three methylene bisflavan-3-ols (1-3), together with a procyanidin dimer, (-)-afzelechin-(4α→8)-(-)-afzelechin (4) were isolated for the first time from the branches and leaves of the titled plant, in addition to 11 known compounds (5-15). Their structures were elucidated by means of extensive spectroscopic analysis and by comparison with data reported in the literatures. Methylene 6,8-bis(7-O-glucosyl) catechin (1) was determined to be a new dimeric flavan-3-ol glycoside through a methylene linkage between C-8 and C-8 of two units. At a concentration of 128?μg/mL, the known compounds 9 – 13 exhibited antibacterial activities on Escherichia coli, Staphylococcus aureus subsp. aureus, Salmonella enterica subsp. enterica, and Pseudomonas aeruginosa. Compound 12 also showed certain glucose uptake stimulating activity.     

Synthesis, structural and crystallographic study of some carbamates derived from 9-methyl-9-azabicyclo[3.3.1]nonan-3α-ol

A series of benzimidazole, thiazole and benzothiazole carbamates derived from 9-methyl-9-azabicyclo[3.3.1]nonan-3α-ol was synthesized and studied by ¹H, ¹³C, 2D NMR and IR spectroscopy. To assist in the interpretation of the spectroscopic data, the crystal structure of 3 (9-methyl-9-azabicyclo[3.3.1]nonan-3α-yl 2-amino-1H-benzimidazole-1-carboxilate) was determined by X-ray diffraction. It has been found that 1-carbamates and 2-carbamates can be obtained in the case of the benzimidazole derivatives. The benzimidazole-1-carbamates are obtained in higher yields (41, 38%) than the benzimidazole-2-carbamates (3, 9%). The compounds studied displayed in CDCl₃ solution a preferred chair–boat conformation with the substituted ring in a distorted boat form and the N–CH₃ substituent in an axial position with respect to the chair piperidine ring. This conformation is similar to that determined by X-Ray diffraction for compound 3.     

Samarium diiodide induced asymmetric synthesis of γ-butyrolactone using chiral auxiliaries derived from isosorbide and isomannide

The asymmetric reductive coupling reaction of various acrylates derived from D-isosorbide and D-isomannide with acetophenone mediated by samarium diiodide to give both enan-tiomers of the optically active γ-butyrolactone was described.The best enantiomeric excess of the products was 60%.     

Kinetics and equilibrium studies of adsorption of chromium(VI) ion from industrial wastewater using Chrysophyllum albidum (Sapotaceae) seed shells

A new biosorbent has been prepared by coating Chrysophyllum albidum (Sapotaceae) seed shells with chitosan and/or oxidizing agents such as sulfuric acid. This study investigated the technical feasibility of activated and modified activated C. albidum seed shells carbons for the adsorption of chromium(VI) from aqueous solution. The sorption process with respect to its equilibria and kinetics as well as the effects of pH, contact time, adsorbent mass, adsorbate concentration and particle size on adsorption was also studied. The most effective pH range was found to be between 4.5 and 5 for the sorption of the metal ion. The pseudo-first-order rate equation by Lagergren and pseudo-second-order rate equation were tested on the kinetic data, the adsorption process followed pseudo-second-order rate kinetics, also, isotherm data was analyzed for possible agreement with the Langmuir and Freundlich adsorption isotherms, the Freundlich and Langmuir models for dynamics of metal ion uptake proposed in this work fitted the experimental data reasonably well. However, equilibrium sorption data were better represented by Langmuir model than Freundlich. The adsorption capacity calculated from Langmuir isotherm was 84.31, 76.23 and 59.63 mg Cr(VI)/g at initial pH of 3.0 at 30 °C for the particle size of 1.00–1.25 mm with the use of 12.5, 16.5 and 2.1 g/L of CACASC, CCASC and ACASC adsorbent mass, respectively. This readily available adsorbent is efficient in the uptake of Cr(VI) ion in aqueous solution, thus, it could be an excellent alternative for the removal of heavy metals and organic matter from water and wastewater.     

Chemoselective Reduction of Some Condensates derived from Chromone-3-carbaldehyde using Sm and Zn

Condensates 4–6 undergo reductive dimerization with Sm in THF containing aqueous NH₄Cl to produce 7–9, whereas with Zn under similar reaction condition 3–5 produce 10–12.