Comparison of different extraction solvent mixtures for characterization of phenolic compounds in strawberries

Eight different solvent mixtures containing acetone or methanol pure or combined with an acid (acetic, formic, hydrochloric) were tested for their efficiency for extraction of phenolic compounds from strawberries belonging to five groups of polyphenols: anthocyanins, flavonols, flavan-3-ols, hydroxycinnamic acid derivatives and conjugated forms of ellagic acid. Twenty-eight compounds from these five groups have been detected and quantified using HPLC-DAD-ESI-MS(n). The yield of each phenolic compound and group was evaluated with regard to the extraction solvent composition. Acetone containing extraction mixtures were superior to the ones containing methanol for extraction yield of total phenolic compounds, which was especially pronounced for the groups of flavan-3-ols and conjugated forms of ellagic acid. The mixture acetone/acetic acid (99:1, v/v) gave the best results for the qualitative and quantitative assay of the polyphenols present in strawberries since all 28 compounds were detected only in these extracts in quantities higher or comparable to the other extraction solvents tested.     

不同提取方式对萱草花中酚类物质及抗氧化活性的影响

为了研究超声、酶解-超声以及发酵-超声3种不同提取方式对萱草花中酚类物质的含量、组成形态及抗氧化活性的影响,以明黄、桔黄、桔红、朱红、大红5种颜色的萱草花为原料,检测不同萱草花中总黄酮和总多酚含量以及1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）和2,2'-联氮-双-3-乙基苯并噻唑啉-6-磺酸（2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid,ABTS）自由基清除率;利用高效液相色谱对游离态、共轭态和结合态3种形态酚类化合物进行测定,并研究其与抗氧化活性的关系。结果表明,不同颜色的萱草花中总黄酮和总多酚含量各不相同,其含量从高到低排列为：\     

马铃薯茎叶挥发性成分的两种提取方法比较

应用水蒸气蒸馏-溶剂萃取法和微波辅助-溶剂萃取法提取了成熟期马铃薯茎叶挥发性成分。用乙醚为萃取溶剂的水蒸气蒸馏法提取时,以0.533%（m/m）得油率获得精油;以正己烷为溶剂的微波辅助萃取法的最适提取条件为：温度60℃,时间9 min,液料比10︰1（V/m）,在此条件下的得油率为0.528%（m/m）。用GC-MS分析检测出水蒸气蒸馏法获得的精油含有81个成分,解析鉴定出占精油相对含量79.386%的43种物质,醇类化合物（24.789%）为主要成分;微波法获得的精油检测出78个成分,解析鉴定出占总精油82.226%的36种成分,酯类化合物（44.482%）为主要成分。2种提取方法获得的精油成分有很大的差别。     

Soluble and bound phenolic compounds in different Bolivian purple corn ( Zea mays L.) cultivars

In nine Bolivian purple corn ( Zea mays L.) varieties the content of phenolic compounds as well as the anthocyanin composition has been determined. The phenotypes under investigation included four red and five blue varieties (Kulli, Ayzuma, Paru, Tuimuru, Oke, Huaca Songo, Colorado, Huillcaparu, and Checchi). In purple corn, phenolic compounds were highly concentrated in cell walls. Thus, simultaneous determination of soluble and bound-form phenolics is essential for analysis, extraction, and quantification. The present study reports the determination of soluble and insoluble-bound fraction of phenolic compounds by HPLC-DAD and HPLC-ESI-MS(n) in Bolivian purple corn varieties. Enzymatic, thermal, and alkaline hydrolyses were used to obtain the cell wall-linked phenolic compounds. Ferulic acid values ranged from 132.9 to 298.4 mg/100 g, and p-coumaric acid contents varied between 251.8 and 607.5 mg/100 g dry weight (DW), respectively, and were identified as the main nonanthocyanin phenolics. The total content of phenolic compounds ranged from 311.0 to 817.6 mg gallic acid equivalents (GAE)/100 g DW, and the percentage contribution of bound to total phenolics varied from 62.1 to 86.6%. The total monomeric anthocyanin content ranged from 1.9 to 71.7 mg cyanidin-3-glucoside equivalents/100 g DW. Anthocyanin profiles are almost the same among the different samples. Differences are observed only in the relative percentage of each anthocyanin. Cyanidin-3-glucoside and its malonated derivative were detected as major anthocyanins. Several dimalonylated monoglucosides of cyanidin, peonidin, and pelargonidin were present as minor constituents.     

Comparison of extraction methods for marker compounds in the essential oil of lemon grass by GC

A gas chromatography flame ionization detection method for the quantification of bioactive marker compounds (neral, geranial, geraniol, limonene, citronellal, and beta-myrcene) in the essential oil of Cymbopogon citratus (lemon grass) was developed. Four procedures for the extraction of essential oils from C. citratus were compared including solvent extraction, steam distillation extraction, accelerated solvent extraction, and supercritical fluid extraction. Solvent extraction by sonication with nonpolar solvents showed comparable results to the steam distillation method. Several commercial products prepared from C. citratus and Cymbopogon flexuosus were analyzed and compared.     

Effects of different organic farming methods on the concentration of phenolic compounds in sea buckthorn leaves

The effects of different cultivation methods on the amount of phenolic compounds in leaves of 1-year-old seedlings of two Finnish sea buckthorn (Hippophae rhamnoides L. ssp. rhamnoides) cultivars 'Terhi' and 'Tytti' were studied in a field experiment established at coastal area in Merikarvia, western Finland. The cultivation methods included different fertilizers (suitable for organic cultivation), mulches (organic and plastic), and land contours (flat vs low hill surface). Two experiments were conducted. The first allowed the estimation of the effects of cultivar, fertilizer, surface contour, and all their interactions, while the other allowed the estimation of the effects of mulches, land contours, and their interactions for the cultivar 'Tytti'. Eleven different hydrolyzable tannins, pentagalloylglucose, and 14 other phenolic compounds were detected by chemical analysis with high-performance liquid chromatography (HPLC). The amount of phenolic compounds varied between different land contours and mulches. The concentrations of gallic acid, pentagalloylglucose, quercetin-3-rhamnoside, monocoumaroyl astragalin A, total hydrolyzable tannins, and condensed tannins were significantly higher on the flat surface than on the low hill surface. The plastic mulch decreased the concentration of gallic acid, hydrolyzable tannins, and condensed tannins compared to the other mulches used. These results suggest ways to cultivate sea buckthorn to produce large amounts of valuable chemicals, especially tannins in the leaves.     

Optimization of extraction of phenolic compounds from flax shives by pressurized low-polarity water

Pressurized low-polarity water (PLPW) extraction of phenolic compounds from flax shive was investigated using statistically based optimization and the "one-factor-at-a-time" method. Extraction variables examined using central composite design (CCD) included temperature, flow rate, and NaOH concentration of the extracting water. Extraction of phenolic compounds including p-hydroxybenzaldehyde, vanillic acid, syringic acid, vanillin, acetovanillone, and feruric acid was affected by temperature and NaOH concentration; and extraction of all phenolic compounds, except ferulic acid, increased with temperature and NaOH concentration of the extracting water. Flow rate had little effect on concentration of phenolic compounds at equilibrium, but the extraction rate at the early phase was higher for higher flow rates. The mechanism of PLPW extraction of flax shive phenolics was also investigated using a two-site kinetic model and a thermodynamic model. To determine the extraction mechanism, flow rate was varied from 0.3 to 4.0 mL/min while temperature and NaOH concentration were fixed at 180 degrees C and 0.47 M, respectively. The flow rate tests showed the extraction rates of total phenolic (TP) compounds increased with flow rate and can be described by a thermodynamic model. The results from the thermodynamic model demonstrated that a K(D) value of 30 agreed with the experimental data in the flow rate range of 0.3-4.0 mL/min. When the effect of the three independent variables was evaluated simultaneously using CCD, a maximum TP concentration of 5.8 g/kg of dry flax shive (DFS) was predicted from the combination of a high temperature (230.5 degrees C), a high initial concentration of NaOH (0.63 M), and a low flow rate (0.7 mL/min). Maximum TP concentration of 5.7 g/kg of DFS was obtained from extraction conditions of 180 degrees C, 0.3 or 0.5 mL/min, and 0.47 M NaOH at equilibrium. A second-order regression model generated by CCD predicted a maximum TP concentration of 5.8 g/kg of DFS under the same extraction conditions, which is well matched with the results from experimental data.     

Comparison of several methods for the extraction of DNA from potatoes and potato-derived products

Eight methods were compared for the extraction of DNA from raw potato tubers, and nine methods were evaluated for the extraction of DNA from dehydrated potato slices, potato flakes, potato flour, potato starch, and two ready-to-eat potato snack foods. Extracts were assessed for yield using a fluorescence-based DNA quantification assay. Real-time amplification of an endogenous gene, sucrose synthase (sus), was used to assess extract and template quality. A CTAB-based method extracted the highest DNA yields from the tuber material. An in-house method, which utilized the Kingfisher magnetic particle processor, yielded the highest template quality from the tubers. For most of the tuber samples, the Kingfisher and CTAB methods recovered the highest levels of amplifiable sus. DNA yields for potato-derived foods generally decreased with the extent that the product had been processed. The methods that utilized the magnetic particle processor delivered the highest template quality from one of the snack products that was particularly high in fat. For most of the remaining processed products, the levels of amplifiable target DNA recovered were roughly correlated with total DNA recovery, indicating that overall yield had greater influence over sus amplification than template quality. The Wizard method was generally the best method for the extraction of DNA from most of the potato-derived foods.     

猪粪和土壤样品中微生物DNA提取方法的比较

猪粪施于土壤可能会对土壤微生物多样性造成影响,为选用同一种DNA提取方法用于土壤和猪粪微生物DNA的提取,该文采用了化学裂解法和试剂盒法同时从土壤和猪粪样品中提取微生物DNA,并对这两种方法的提取DNA的效果进行了比较。结果表明,试剂盒法不能用于提取土壤中的微生物DNA;可以从猪粪中提取到DNA,PCR扩增能得到目的产物,但重复性不高。化学裂解法提取的土壤微生物DNA浓度高但纯度低,纯化后纯度增加,但DNA有所损失,用于PCR扩增时结果不理想;处理猪粪样品,提取的DNA浓度较低但纯度较高,PCR扩增结果比较理想。由此可见,化学裂解法用来提取猪粪样品中的微生物DNA是可行的,但需寻求更好的土壤样品微生物DNA的提取方法。     

猪粪和土壤样品中微生物DNA提取方法的比较

猪粪施于土壤可能会对土壤微生物多样性造成影响，为选用同一种DNA提取方法用于土壤和猪粪微生物DNA的提取，该文采用了化学裂解法和试剂盒法同时从土壤和猪粪样品中提取微生物DNA，并对这两种方法的提取DNA的效果进行了比较。结果表明，试剂盒法不能用于提取土壤中的微生物DNA；可以从猪粪中提取到DNA，PCR扩增能得到目的产物，但重复性不高。化学裂解法提取的土壤微生物DNA浓度高但纯度低，纯化后纯度增加，但DNA有所损失，用于PCR扩增时结果不理想；处理猪粪样品，提取的DNA浓度较低但纯度较高，PCR扩增结果比较理想。由此可见，化学裂解法用来提取猪粪样品中的微生物DNA是可行的，但需寻求更好的土壤样品微生物DNA的提取方法。     

Influence of ethanol concentration on the extraction of color and phenolic compounds from the skin and seeds of Tempranillo grapes at different stages of ripening

The aim of this paper is to study how grape ripeness and ethanol concentration affect the extraction of color and phenolic compounds from skins and seeds during the maceration/fermentation process. Simulated maceration assays were carried out with the grapes at three stages of berry development (vitis vinifera cv. Tempranillo) and different percentages of ethanol in the maceration media. Both ripeness and ethanol content have a considerable effect on the extraction of color and phenolic compounds. Of these two factors, ripeness increases the extractability most. The presence of ethanol in the medium facilitates anthocyanin and especially proanthocyanidin extraction, but it also decreases copigmentation phenomena, which can decrease the color intensity. The higher the ethanol concentration is in the maceration media, the higher the astringency of proanthocyanidins.     

Comparison of methods for extraction of organic N monomers from soil microbial biomass

One way of investigating the function of soil is via the pool of low molecular weight organic compounds in the soil microbial biomass. This is because low molecular weight organic compounds have key roles in metabolism of soil microbes, can function in osmotic adjustment and other stress responses, and are intermediates in the breakdown of polymers to inorganic nutrients. Methods for measuring low molecular weight microbial metabolites in soil rely upon extracting total metabolites and then subtracting the contribution from metabolites in the soil extracellular matrix (i.e. microbial = total − extracellular). Recent studies have tested methods for extracting organic N monomers from the extracellular matrix of soil, but there has not been similar testing of methods for extracting total organic N monomers. The aims of this study were to examine methods for extracting total organic N monomers by a) contrasting chloroform gas fumigation with chloroform direct extraction, and b) examining whether it is possible to extract soil with two methods that combine quenching of metabolic activity with extraction, namely cold methanol/chloroform/water and hot aqueous ethanol. To evaluate methods, organic N compounds were extracted from soil and then capillary electrophoresis–mass spectrometry identified and quantified 42 organic N monomers including amino acids, quaternary ammonium compounds, nucleobases and nucleosides, amines and polyamines. Absolute concentrations of 32 out of the 42 quantified organic N monomers were significantly different between soil extracted by chloroform gas fumigation and chloroform direct extraction. These differences were probably a function of gains and losses of compounds due to oxidation, hydrolysis and deamidation during the two-day chloroform gas fumigation. Cold methanol/chloroform/water yielded large amounts of the extremely labile compound ergothioneine, probably because the extraction method rapidly quenched metabolic activity. The primary limitation of extraction with methanol/chloroform/water is that it was ineffective at extracting strongly cationic compounds (e.g. polyamines). Extraction with hot aqueous ethanol was unsuccessful with soil presumably because soil microbes are difficult to lyse. It is recommended that future studies examining organic N monomers in soil microbial biomass use chloroform direct extraction or cold methanol/chloroform/water rather than chloroform gas fumigation.     

In vitro bioavailability of phenolic compounds from five cultivars of frozen sweet cherries (Prunus avium L.)

The bioavailability of phenolic compounds from five cultivars of frozen sweet cherries was assessed by a digestion process involving pepsin-HCl digestion (to simulate gastric digestion) and pancreatin digestion with bile salts (to simulate small intestine conditions) and dialyzed to assess serum- and colon-available fractions. After pepsin digestion, the % recovery of total phenolics, relative to the original starting material, increased, whereas the % anthocyanins did not change. Following pancreatic digestion and dialysis, the total phenolics in the IN (serum-available) fraction was about 26-30% and the OUT (colon-available) fraction was about 77-101%. The anthocyanin content in the IN fraction was 15-21%, and in the OUT fraction, it was 52-67%. Skeena, Lapins, and Sweetheart cultivars contained higher levels of total phenolics and anthocyanins, which resulted in higher concentrations of these compounds in the IN and OUT fractions. The potential bioavailability of phenolic compounds was also assessed in Bing and Lapins cultivars at three ripening stages. Immature cherries had higher % total phenolics in the IN fraction than mature or overmature cherries. However, immature cherries had the lowest concentrations of these compounds, making the actual bioavailable amounts of these compounds lower than for mature and overmature fruit. High-performance liquid chromatography analysis of Lapins cherries at three maturity stages confirmed the results obtained using spectrophotometric methods for total phenolics and anthocyanins.     

Studies on the key aroma compounds in soy milk made from three different soybean cultivars

An investigation by aroma extract dilution analysis (AEDA) of the aroma concentrate of soy milk made from a major Japanese soybean cultivar, Fukuyutaka (FK), revealed 20 key aroma compounds having flavor dilution (FD) factors of not less than 64. Among them, 2-isopropyl-3-methoxypyrazine, cis-4,5-epoxy-(E)-2-decenal, trans-4,5-epoxy-(E)-2-decenal, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, and 2'-aminoacetophenone were identified as the key aroma compounds in soy milk for the first time. (E,E)-2,4-Decadienal exhibiting a fatty note and trans-4,5-epoxy-(E)-2-decenal exhibiting a metallic/sweet note were detected as having the highest FD factors of 4096, followed by hexanal (green), (E)-2-nonenal (fatty), and (E,E)-2,4-nonadienal (fatty) having FD factors of 1024. Although all of these compounds might be generated from lipids, various aroma components, which were thought to be generated from amino acids, sugars, and ferulic acid, were detected having FD factors of 64-256. Investigation by comparative AEDA experiments of the soy milk aroma concentrates of two cultivars for soybean curd and soy milk, FK and Vinton81 (VT), and one cultivar for boiled beans, Miyagishirome (MY), revealed that most of the key aroma compounds were common to all of them, but 2-isopropyl-3-methoxypyrazine, exhibiting a pea-like/earthy note, was detected only in FK and VT. In addition, a sensory experiment revealed that the pea-like/earthy notes in FK and VT were significantly stronger than that in MY. These results demonstrated that a pea-like/earthy note contributed by 2-isopropyl-3-methoxypyrazine might be one of the essential characteristics to describe soy milk aromas.     

Comparison of volatile compounds isolated from the skin and flesh of four potato cultivars after baking

Four potato cultivars, Cara, Nadine, Fianna, and Marfona, were selected. Potatoes were baked in their skins prior to separating the skin and flesh and preparing extracts of the volatile flavor compounds using a modified Likens--Nickerson apparatus. The concentrated extracts were analyzed by gas chromatography--mass spectrometry. Volatiles were identified and classified according to their origin, that is, lipid, sugar degradation and/or Maillard reaction not involving sulfur amino acids, sulfur compounds, methoxypyrazines, and other compounds. Quantitative and qualitative differences were observed between isolates from flesh and skins and among cultivars grown at different sites. Strongest isolates from skin were obtained for Nadine. For flesh, Cara gave isolates approximately 10-fold more concentrated than the other three cultivars. For skin, sugar degradation and/or the Maillard reaction was by far the most important source in all cultivars except Nadine, for which 62% of the volatiles were accounted for by the sesquiterpene solavetivone. Lipid and sugar degradation and/or the Maillard reaction were the main origins of volatiles in flesh. Calculated aroma values for a selection of the key potato volatiles identified reinforce the effects of cultivar and growing site on baked potato flavor.     

Microwave-assisted extraction of bound phenolic acids in bran and flour fractions from sorghum and maize cultivars varying in hardness

To release bound phenolic acids, a microwave-assisted extraction procedure was applied to bran and flour fractions obtained from eight sorghum and eight maize cultivars varying in hardness. The procedure was followed by HPLC analysis, and the identities of phenolic acids were confirmed by MS/MS spectra. The extraction of sorghum and maize bound phenolic acids was done for 90 s in 2 M NaOH to release ferulic acid and p-coumaric acid from bran and flour. Two diferulic acids, 8-O-4'- and 8-5'-benzofuran form, were identified and quantitated in sorghum bran, and only the former was found in maize bran. The contents of ferulic acid and diferulic acids in sorghum bran were 416-827 and 25-179 μg/g, respectively, compared to 2193-4779 and 271-819 μg/g in maize. Phenolic acid levels of sorghum were similar between hard and soft cultivars, whereas those of maize differed significantly (p < 0.05) except for ferulic acid in flour. Sorghum phenolic acids were not correlated with grain hardness as measured using a tangential abrasive decortication device. Maize ferulic acid (r = -0.601, p < 0.01), p-coumaric acid (r = -0.668, p < 0.01), and 8-O-4'-diferulic acid (r = -0.629, p < 0.01) were significantly correlated with hardness.     

提取方法对核桃青皮多酚提取效果的影响

为研究不同提取方法对核桃青皮多酚提取效果的影响,以乙醇为提取溶剂,分别采用溶剂提取法、微波辅助提取法、超声波辅助提取法、六偏磷酸钠（SHMP）辅助提取法提取核桃青皮多酚。研究结果表明：在试验条件下不同提取方法对核桃青皮的影响效果不同,其中SHMP辅助微波提取法效果最好,得率为4.01?mg/g,高于对照溶剂提取法的73.4%。因此,SHMP辅助微波提取方法是一种新型高效的核桃青皮多酚提取方法。     

Antioxidant properties of phenolic compounds from Pelargonium reniforme

Flavonoids and hydrolyzable tannins isolated from Pelargonium reniforme were evaluated for their antioxidant ability using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical generating system and a luminol-dependent chemiluminescence assay. In both assays, the polyphenols tested showed higher radical scavenging activities than the reference antioxidant, ascorbic acid (IC50 2.6-32.9 microM vs 40.9 microM in the DPPH test, and 2-25 times stronger effects in the chemiluminescence assay). A comparison of the flavonoids and the tannins showed that the latter have more potential than the former. Structural requirements for marked antioxidant activities of hydrolyzable tannins were the presence of galloyl and hexahydroxydiphenoyl groups, and apparently carbonyl (ester) functionalities in oxidatively modified dehydrohexa-hydroxydiphenoyl moieties. For flavonoids, it appeared that a catechol (3',4'-dihydroxy) element in the B-ring were important determinants and that O-glycosides were more effective than flavone-based C-glucosyls. Conspicuously, introduction of a galloyl group significantly enhanced their potentials. The demonstrated marked antioxidant effects of the polyphenols provide a clue for beneficial effects of P. reniforme in the treatment of liver disorders among several ethnic groups in areas of southern Africa.     

Comparison among soil Series and extraction methods for the analysis of trifluralin

Accurate analytical procedures are needed to improve understanding of the fate and transport of trifluralin, a chemical widely used as a herbicide. Analytical determination of trifluralin is challenging due to its hydrophobic, yet volatile, character and its tendency to degrade into numerous metabolites. In this research, efficient analytical methods for fortified and field-incurred soils were developed for simultaneous quantitation of trifluralin, I [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine, CAS Registry No. 1582-09-8; CAS Registry No. have been provided by the author], a trifluralin metabolite, II [2,6-dinitro-N-propyl-4-(trifluoromethyl)benzenamine, CAS Registry No. 2077-99-8], and a related trifluoromethyldinitroaniline isomer of trifluralin, III [2,4-dinitro-N,N-dipropyl-6-(trifluoromethyl)benzenamine, CAS Registry No. 23106-20-9]. Extractions of trifluralin (0.5 and 2.5 microg/g) from silt loam, sandy loam, and silty clay soils were compared. A method was developed for the supercritical fluid extraction of trifluralin from soil using modified supercritical carbon dioxide, and the effects of cosolvent, pressure, and flow rate on recovery were evaluated. Supercritical fluid extraction was compared to liquid vortex extraction and automated Soxhlet (soxtec) extraction. Solid-phase extraction was examined for purifying soil extracts. Protocols were developed for analysis of extracts by gas and/or liquid chromatography. Immunoassay was investigated but proven to be impractical for this analysis. Soil properties and extraction methods were observed to affect the level of coextracted background interferences. Trifluralin exhibited concentration-dependent recovery regardless of soil series or extraction method.     

Echinacea standardization: analytical methods for phenolic compounds and typical levels in medicinal species

A proposed standard extraction and HPLC analysis method has been used to measure typical levels of various phenolic compounds in the medicinally used Echinacea species. Chicoric acid was the main phenolic in E. purpurea roots (mean 2.27% summer, 1.68% autumn) and tops (2.02% summer, 0.52% autumn), and echinacoside was the main phenolic in E. angustifolia (1.04%) and E. pallida roots (0.34%). Caftaric acid was the other main phenolic compound in E. purpurea roots (0.40% summer, 0.35% autumn) and tops (0.82% summer, 0.18% autumn), and cynarin was a characteristic component of E. angustifolia roots (0.12%). Enzymatic browning during extraction could reduce the measured levels of phenolic compounds by >50%. Colorimetric analyses for total phenolics correlated well with the HPLC results for E. purpurea and E. angustifolia, but the colorimetric method gave higher values.