Silica Gel Fractionation Research Articles

The Self-Disproportionation of Enantiomers (SDE) of α-Pinene via Evaporation off Silica Gel and Foam Fractionation—Validation of the Plausibility of SDE via Gas Chromatography (GC) for α-Pinene

α-Pinene is an intriguing monoterpene as it has been reported to undergo the self-disproportionation of enantiomers (SDE) phenomenon via gas chromatography (GC), the only compound to decisively demonstrate this. Examples of the SDE involving the gaseous phase—sublimation aside—are extremely rare. Attempts to replicate the GC results were unsuccessful, though the authors argued convincingly for the difficulty of observing the phenomenon. However, we could effect for α-pinene SDE via evaporation off silica gel and by foam fractionation—albeit the SDE magnitude for both was only very slight—to confirm that α-pinene can undergo the SDE for processes involving a gaseous phase and thus validate the plausibility of the GC report. The indications are that the molecular associations responsible for the various SDE observations of α-pinene occur not in the gaseous phase or the bulk phase but rather in two-dimensional (2D) adsorbed monolayers and are not based on conventional functional group-based intermolecular interactions and instead are, most likely, as a result of homo- and heterochiral packing differences in the 2D monolayers—a well-known 2D chiral-based association packing effect. These are also the first reports of the occurrence of the SDE using an adsorptive bubble separation process (foam fractionation) and involving a gaseous phase other than sublimation, GC, and distillation.

Evaluation of antioxidant, antimicrobial and antitumor compounds production potential of Streptomyces antioxidans PU-12M

Streptomycetes are prolific producers of biologically active secondary metabolites with great structural and functional diversity, which are widely used as pharmaceutical products. The strain Streptomyces sp. PU-12M was investigated for its potential to produce antioxidant, antimicrobial and antitumor compounds. For this purpose, the laboratory scale fermentation (10 liters working volume) of the strain was performed followed by cell separation, solvent extraction and partial purification of biologically active compounds by silica gel fractionation column chromatography and preparative TLC. The antioxidant activity was determined by DPPH radical scavenging assay, antimicrobial activity by agar well diffusion assay while in vitro antitumor activity was determined by MTT and SRB assays. Altogether 24 partially purified compounds or fractions were retrieved from the extract of strain Streptomyces Sp. PU-12M and were subsequently investigated for biological activity. Among them, three fractions were found to have potent antioxidant activity. The crude extracts and the partially purified fractions were found to have promising antimicrobial activity with MIC up to 3.2mg/ml. The partially purified fractions exhibited varied cytotoxicity ranging from 40% to 100% mortality against brine shrimp (Artemia salina) larvae and 22% to 67% growth inhibition of HCT 116 colorectal cancer cell lines. The study reveals that Streptomyces antioxidans PU-12M is a proliferent producer of bioactive secondary metabolites and can be exploited further to produce the commercially useful bioactive molecules.

Stabilization of Refined Olive Oil with Phenolic Monomers Fraction and Purified Hydroxytyrosol from Olive Mill Wastewater

The aim of this study was to enhance the refined olive oil (ROO) quality stabilization during storage with phenolic compound fractions obtained from C18 silica gel fractionation of olive mill waste (OMW) ethyl acetate extract. HPLC–DAD–ESI/MS analysis was used to identify the main phenolic compounds present in the obtained fractions. 16 compounds were identified belonged to four classes: simple phenols, secoiridoids, flavonoids, and lignans. In this study, Diosmetin was identified for the first time in OMW and the major compound was hydroxytyrsol. On the other hand OMW extract and its related fractions conserved their antioxidant activity until 110 min heating at 185 °C. In addition, physicochemical characteristics such as peroxide value as well as conjugated dienes (CD) and conjugated trienes (CT) were determined to evaluate the oxidation of OMW polyphenols-enriched ROO during storage. Results demonstrated that OMW monomeric fraction and hydroxytyrosol improved the quality of ROO by decreasing peroxide value and absorptions at specified wave lengths at 232 and 270 nm related to conjugated dienes and trienes formation, respectively. This study suggests that the enrichment of ROO with phenolic compounds from OMW mainly hydroxytyrosol makes the oil more functional with a higher stability. Phenolic compounds from OMW with antioxidant activity improve the stability of ROO during storage and hence would be used as a natural alternative for chemical additives.

Protective effect of Coleus forskohlii leaf-extract compound on progression of cataract against Fructose-Induced experimental cataract in rats

The present study was designed to determine protective effects of Coleus forskohlii hydroalcoholic leaf-extract along with its fractions against fructose-induced cataract rat model. The Coleus forskolii leaf extract was subjected to silica gel column chromatography and fractions were collected. A major high yielding fraction of the leaf extract, designated as fraction B6 was pharmacologically evaluated in Sprague Dawley albino rats at three doses 0.1, 1 and 10 mg/kg respectively. Compound B2; isolated from B6 fraction, identified as ‘gallic acid’ was also pharmacologically evaluated at three different doses. Cataract was induced by concurrent administration of fructose solution (10% w/v, per oral, dissolved in drinking water) for eight consecutive weeks. Mean arterial pressure, blood glucose level and lenticular opacity were determined. At the end of eight weeks, C. forskohlii leaf extract fraction and gallic acid reduced mean arterial pressure and glucose level in a dose dependent manner. In addition, C. forskohlii led to significant restoration of lens antioxidants enzyme level and reduced cataract formation in rats. These results showed the concentration dependent protective effect by C. forskohlii leaf extract against cataract formation due to restoration of oxidative stress markers.

Compositional and Structural Analysis of Silica Gel Fractions from Municipal Waste Pyrolysis Oils

Hydrocarbon-rich pyrolysis oils produced from landfill waste and recycled plastics are potential sources for fuels and chemicals. It is well established that feedstock composition significantly affects pyrolysis oil composition and, hence, its potential uses. For example, plastics waste pyrolysis oils contain a high concentration of hydrocarbons, whereas biomass pyrolysis oils have high oxygen content. Previous studies have shown that the addition of plastics to a biomass feedstock increases the hydrocarbon content; however, a detailed analysis of hydrocarbons and polar species from pyrolysis oils produced from “real world” mixed municipal waste materials has not yet been done. Here, the silica gel fractions from unsorted landfill waste and mixed recycled plastics pyrolysis oils are analyzed by two-dimensional gas chromatography (GC × GC), field ionization mass spectrometry (FI-MS), Fourier transform infrared spectroscopy (FT-IR), and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS)...

Environmental mixture with estrogenic activity increases Hsd3b1 expression through estrogen receptors in immature rat granulosa cells.

Humans are exposed not only to single endocrine disruptors, but also to chemical mixtures that can adversely affect their reproductive health. Steroidogenesis in reproductive tissues is emerging as the key target of endocrine disruptor action. Here, we analyzed the effect of environmental chemical mixtures with estrogenic activity on steroidogenic processes in immature rat granulosa cells and whether the observed steroidogenic effects were mediated through estrogen receptors. Extracts from untreated wastewater were prepared by solid-phase extraction and silica gel fractionation. ER-CALUX assay showed that the polar fractions of wastewater exerted different levels of estrogenic activity. Exposure of immature granulosa cells to the polar fraction exerting 9ng of 17β-estradiol equivalents per liter of water of estrogenic activity increased mRNA expression of the key enzymes of progesterone biosynthetic pathway Star and Hsd3b1, but did not alter the level of Cyp19a1 and Lhr. Addition of estrogen receptor inhibitor ICI 182 780 prevented the estrogenic mixture-induced increase in Hsd3b1, but not Star mRNA level in immature granulosa cells. These results indicate that the environmental chemical mixtures with estrogenic activity exert endocrine disrupting effects by augmenting the progesterone biosynthetic pathway in immature rat granulosa cells, which is an effect achieved in part through activation of the estrogen receptors.

Combined cluster and discriminant analysis: An efficient chemometric approach in diesel fuel characterization

Combined cluster and discriminant analysis (CCDA) as a chemometric tool in compound specific isotope analysis of diesel fuels was studied. The stable carbon isotope ratios (δ13C) of n-alkanes in diesel fuel can be used to characterize or differentiate diesels originating from different sources. We investigated 25 diesel fuel samples representing 20 different brands. The samples were collected from 25 different service stations in 11 European countries over a 2 year period. The n-alkane fraction of diesel fuels was separated using solid-state urea clathrate formation combined with silica gel fractionation. The stable carbon isotope ratios of C10–C24 n-alkanes were measured with gas chromatography–isotope ratio mass spectrometry (GC–IRMS) using perdeuterated n-alkanes as internal standards. Beside the 25 samples one additional diesel fuel was prepared and measured three times to get totally homogenous samples in order to test the performance of our analytical and statistical routine.Stable isotope ratio data were evaluated with hierarchical cluster analysis (HCA), principal component analysis (PCA) and CCDA. CCDA combines two multivariate data analysis methods hierarchical cluster analysis with linear discriminant analysis (LDA). The main idea behind CCDA is to compare the goodness of preconceived (based on the sample origins) and random groupings. In CCDA all the samples were compared pairwise.The results for the parallel sample preparations showed that the analytical procedure does not have any significant effect on the δ13C values of n-alkanes. The three parallels proved to be totally homogenous with CCDA.HCA and PCA can be useful tools when the examining of the relationship among several samples is in question. However, these two techniques cannot be always decisive on the origin of similar samples. The initial hypothesis that all diesel fuel samples are considered chemically unique was verified by CCDA. The main advantage of CCDA is that it gives an objective index number about the level of similarity among the investigated samples. Thus the application of CCDA supplemented by the traditionally used multivariate methods greatly improves the efficiency of statistical analysis in the CSIA of diesel fuel samples.

Toxicological and chemical investigation of untreated municipal wastewater: Fraction- and species-specific toxicity

Absence of a municipal wastewater (WW) treatment plant results in the untreated WW discharge into the recipient. The present study investigated toxic effects and chemical composition of water extracts and fractions from untreated WW and recipient Danube River (DR). Samples were prepared by solid-phase extraction and silica gel fractionation and screened for EROD activity and cytotoxicity using aquatic models, comprising of fish liver cells (PLHC-1) and a model of the early development of zebrafish embryos, while rat (H4IIE) and human (HepG2) hepatoma cells served as mammalian models. Polar fraction caused cytotoxicity and increased the EROD activity in PLHC-1 cells, and increased mortality and developmental abnormalities in developing zebrafish embryos. In H4IIE, polar fraction induced inhibition of cell growth and increased EROD activity, whereas HepG2 exerted low or no response to the exposure. Non-polar and medium-polar fractions were ineffective. Tentative identification by GC/MS showed that WW is characterized by the hydrocarbons, alkylphenols, plasticizers, and a certain number of benzene derivatives and organic acids. In DR, smaller number of organic compounds was identified and toxicity was less pronounced than in WW treatments. The present study revealed the potent toxic effect of polar fraction of untreated WW, with biological responses varying in sensitivity across organisms. Obtained results confirmed that fraction- and species-specific toxicity should be considered when assessing health risk of environmental pollution.

Gallic acid as the major antioxidant in pequi (Caryocar brasiliense Camb.) fruit peel

ABSTRACTIn this study, ethanol-water extracts of pequi fruit peel were fractionated in order to identify and quantify the major antioxidant present in it. The fractions were subjected to liquid-liquid phase extraction and silica-gel column chromatography, and antioxidant activity was monitored using the 2,2-diphenyl-1-picrylhydrazyl radical-scavenging assay. The purity of the fractions was evaluated using thin-layer chromatography and high-performance liquid chromatography (HPLC). The substance with antioxidant property was identified through the analysis in a liquid chromatography-mass spectroscopy fragmentation and was quantified using HPLC. After the Silica-gel fractionation, it was identified a fraction with high antioxidant activity and purity, which contained gallic acid as the main compound. The gallic acid was found at the amount of 26.54 ± 1.13 mg/g of the dry mass of the pequi fruit peel. Because the quantifications were performed using crude ethanol-water extract, it was suspected that gallic acid was present in a free form. Thus, pequi fruit peel may serve as an attractive alternative of feedstock for natural antioxidant production. Moreover, the results obtained in this study emphasize the value of the pequi plant, and suggests improved opportunities for families that use this fruit`s products.

Toxicological profiles assessment of the water and sediments from the Krivaja and Jegrička Rivers, Serbia

This study utilizes a combinatorial bio/chemical approach to assess the toxicological profiles of organic pollutants in water and sediment samples from two watercourses that are under significant anthropogenic pressure—the Krivaja and Jegrička rivers in Serbia. Sample preparation by solid-phase extraction and silica-gel fractionation followed by GC/MS analysis, allowed the tentative identification of a variety of non-target contaminants, divided into non-polar, medium-polar and polar fractions. The instrumental analysis revealed slightly different toxicological profiles for the water and sediment from both rivers, and confirmed the presence of various classes of organic contaminants, from non-polar hydrocarbons, to more polar compounds such as aldehydes, ketones and phenols. Polycyclic aromatic hydrocarbons and pesticides were identified, but below toxicologically relevant concentrations. The results of bioanalyses on H4IIE and PLHC-1 cells indicated that cytotoxic potential was pronounced in Jegrička water and sediment samples, and CYP1A inducing potential was observed in both Krivaja and Jegrička sediment samples, although they did not reflect high levels of contamination. Based on the overall data, the sediments of the Krivaja and Jegrička rivers are a more toxicologically relevant matrix than the water.

THE MOLECULAR PROPERTIES OF GHATTI GUM: A NATURALLY OCCURRING POLYELECTROLYTE.

Abstract An authenticated sample of ghatti gum from Anogeissus latifolia has been fractionated by ethanolic precipitation (Fraction I), and chromatography on silica gel (Fractions 2 and 3). The equivalent weights found were 1,750, 1,800 and 2,040 respectively. The sodium salts of the fractions have been studied in various salt solutions by viscosity and light scattering methods. From the latter the molecular weights (= 2·1, 2·7, and 2·6 ± 106 respectively), radii of gyration, and some idea of molecular shape have been obtained. The molecule appears to be rod shaped. The expansion factors of the molecules calculated from the light scattering and the viscosity data agree with each other. Reasons for the difference in the values of the calculated and observed second virial coefficients are discussed.

An analytical and theoretical approach for the profiling of the antioxidant activity of essential oils: The case of Rosmarinus officinalis L.

The antioxidant constituents of essential oils (EOs) of Rosmarinus officinalis L. (α-pinene chemotype) were isolated at the flowering (A), post-flowering (B), and vegetative stages (C). GC–MS was used to analyze total chemical composition, Folin–Ciocalteau and Prussian blue methods for reducing substances. Radical scavenging capacity (DPPH test, IC 50 36.78 ± 0.38, 79.69 ± 1.54, 111.94 ± 2.56 μL) and anti-lipoperoxidant activity (TBARS, IC 50 0.42 ± 0.04, 1.20 ± 0.06 μL, 4.07 ± 0.05 μL) differed widely in the three stages. Antioxidant activity, identified after silica gel fractionation chromatography, was closely related ( R 2 = 0.9959) to each EO's content of hydroxilated derivatives, (containing alcohols, phenols and 1,8 cineole): 15.26 ± 0.12%, 7.22 ± 0.06%, and 5.09 ± 0.10% in EOs from A, B, and C. Modeling the C, H, O terpenes in a simulated phospholipid bilayer indicated that anti-lipoperoxidant activity depended on the stability and rapidity of their interactions with the membrane bilayer components, and their positioning over its surface.

Assessment of toxicological profiles of the municipal wastewater effluents using chemical analyses and bioassays

The hazardous chemical contamination of untreated wastewater and secondary effluent from the wastewater treatment plant (WWTP) of the city of Zagreb, Croatia was comprehensively characterized using large-volume solid-phase extraction (SPE) and silica gel fractionation, followed by a detailed analysis of the resulting extracts by a combination of chemical and bioassay methods. Over 100 individual contaminants or closely related-contaminant groups were identified by high-resolution gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/quadrupole time-of-flight mass spectrometry (LC-QTOF). Ecotoxicity profiling of the investigated samples, including cytotoxicity, chronic toxicity and EROD activity; inhibition of the multixenobiotic resistance (MXR), genotoxicicity and estrogenic potential, revealed the most significant contribution of toxic compounds to be present in polar fractions. Wastewater treatment using conventional activated sludge process reduced the initial toxicity of raw wastewater to various extents, ranging from 28% for algal toxicity to 73.2% for an estrogenic activity. The most efficient toxicity removal was observed for the polar compounds.

Characterization of military fog oil by comprehensive two-dimensional gas chromatography

The most commonly used military fog oil is characterized by comprehensive two-dimensional gas chromatography (GC×GC) coupled to either Flame Ionization Detection (FID) or Time-of-Flight Mass Spectrometric Detection (TOFMS) to advance the knowledge regarding the complete chemical makeup of this complex matrix. Two different GC×GC column sets were investigated, one employing a non-polar column combined with a shape selective column and the other an inverse column set (medium-polar/non-polar). The inverse set maximizes the use of the two-dimensional separation space and segregates aliphatic from aromatic fractions. The shape selective column best separates individual polycyclic aromatic hydrocarbons (PAHs) from the bulk oil. The results reveal that fog oil (FO) is composed mainly of aliphatic compounds ranging from C 10 to C 30, where naphthenes comprise the major fraction. Although many different species of aromatics are present, they constitute only a minor fraction in this oil, and no conjugated PAHs are found. The composition of chemically similar aliphatic constituents limits the analytical power of silica gel fractionation and GC–MS analysis to characterize FO. Among the aliphatic compounds identified are alkanes, cyclohexanes, hexahydroindanes, decalins, adamantanes, and bicyclohexane. The aromatic fraction is composed of alkylbenzene compounds, indanes, tetrahydronaphthalenes, partially hydrogenated PAHs, biphenyls, dibenzofurans and dibenzothiophenes. This work represents the best characterization of military fog oil to date. As the characterization process shows, information on such complex samples can only be parsed using a combination of sample preprocessing steps, multiple detection schemes, and an intelligent selection of column chemistries.

The Adjuvant Effect of Ambient Particulate Matter Is Closely Reflected by the Particulate Oxidant Potential

The Adjuvant Effect of Ambient Particulate Matter Is Closely Reflected by the Particulate Oxidant Potential

Isolation and Identification of Insecticidal Components from Citrus aurantium Fruit Peel Extract

Three active components were identified by bioassay-guided fractionation of bitter orange ( Citrus aurantium L.) fruit peel petroleum ether extract. Silica gel fractionation of the extract yielded a fraction that inflicted up to 96% mortality to adults of the olive fruit fly Bactrocera oleae (Gmelin) three days post-treatment. Subsequent HPLC purification of the active fraction resulted in the isolation of three components, eluted in fractions F 222, F 224, and F 226, that induced adult mortality. Considering the data obtained from UV, FTIR, MS, and (1)H NMR spectra, they were identified as 7-methoxy-8-(3'-methyl-2'-butenyl)-2 H-1-benzopyran-2-one (osthol), 4-methoxy-7 H-furo[3,2- g]benzopyran-7-one (bergapten), and 4-(( E)-3'-methyl-5'-(3'',3''-dimethyloxiran-2''-yl)pent-2'-enyloxy)-7 H-furo[3,2- g][1]benzopyran-7-one (6',7'-epoxybergamottin). Our results are in concordance with those reported in the literature and were further verified by direct comparison to authentic components. 6',7'-Epoxybergamottin was toxic when tested individually, while bergapten and osthol were found to act synergistically to 6',7'-epoxybergamottin.

Effect of bioactive fractions of Citrullus vulgaris Schrad. leaf extract against Anopheles stephensi and Aedes aegypti

The benzene extract of Citrullus vulgaris was tested against Anopheles stephensi and Aedes aegypti for the larvicidal activity and ovicidal properties. The crude benzene extract was found to be more effective against A. stephensi than A. aegypti. The LC50 values were 18.56 and 42.76 ppm respectively. The LC50 values for silica gel fractions (bioactive fractions I, II, III and IV) were 11.32, 14.12, 14.53 and 16.02 ppm respectively. The mean per cent hatchability of the egg rafts were observed after 48 h post treatment. The crude extract of benzene exerted 100% mortality at 250 ppm against A. stephensi and at 300 ppm against A. aegypti. The silica gel fractions I and II afforded 100% mortality at 100 ppm and III and IV exerted the hatchability rate of 4.9 and 5.3% at the same concentration against A. stephensi.

Fate of oestrogenic compounds and identification of oestrogenicity in a wastewater treatment process

Understanding of the fate of oestrogen and oestrogenic compounds is important in improving the removal efficiency for oestrogens in wastewater treatment plants (WWTPs). In this study an attempt was made to clarify the fate of oestrogen, oestrogen sulphates, and oestrogenic compounds (synthetic oestrogen, nonylphenol and its relatives) by an instrumental analysis, and the fate of oestrogenicity by an in vitro assay. The investigation was conducted in an activated sludge WWTP in winter and summer, focusing on identification of the primary substances that induce oestrogenicity. Wastewater samples were analysed by employing the silica-gel fractionation technique in conjunction with two-step column chromatography. The results revealed that, in winter, the WWTP efficiencies for the removal of nitrogen and oestrogens decreased and the oestrone level increased with the progress of the treatment. Oestrone and oestrogenic substances are likely to circulate between the aeration tank and the final sedimentation tank. In summer, however, these compounds were effectively removed in the WWTP. The results of the column chromatography coupled with the bioassay suggested that E1 and E2 are the predominant contributors to the oestrogenicity in the influent, return sludge and effluent of the WWTP. The measurement by the instrumental analysis supported these findings.

Simultaneous determination of endocrine-disrupting phenols and steroid estrogens in sediment by gas chromatography–mass spectrometry

A simple and effective method has been developed to simultaneously determine endocrine-disrupting phenolic xenoestrogens and steroid estrogens in sediment by using ultra-sonicated extraction in combination with silica gel fractionation, derivatization with pentafluropropionic anhydride, and gas chromatography–mass spectrometry (GC–MS) in selected ion monitoring mode (SIM). Satisfactory recoveries have been obtained for phenolic xenoestrogens and steroid estrogens. The method enables the determination of targets at concentrations of lower nanogram-per-gram in sediments. The method has been successfully applied to the sediments collected from Pearl River Estuary (PRE), South China Sea, China. Nonylphenol and bisphenol-A (BPA) were detected in the range from 204.2 to 664.5 ng/g and 0.6 to 4.0 ng/g, respectively. None of the estrogens were found in the sediment samples.

Chemopreventive Activity of Polyphenolics from Black Jamapa Bean (Phaseolus vulgaris L.) on HeLa and HaCaT Cells

The antiproliferative effects of 100% methanol crude extract and of Toyopearl and silica gel fractions from the seed coats of black Jamapa beans (Phaseolus vulgaris L.) were evaluated using HeLa, human adenocarcinoma cells, and HaCaT, human premalignant keratinocytes. The 100% methanol crude extract [172.2 microM equiv of (+)-catechin] increased adhesion of HeLa cells; however, 3- and 5-fold higher concentrations decreased the number of cells attached as a function of the treatment time. The highest concentration tested diminished the cell adhesion until 40% (after 24 h) to almost 80% (after 72 h). The IC50 values showed that the 100% methanol crude extract was the most effective inhibitor of HeLa cell proliferation, even when it was dissolved in dimethylsulfoxide (DMSO) [34.5 microM equiv of (+)-catechin] or in medium [97.7 microM equiv of (+)-catechin]. The Toyopearl 5 (TP5) fraction and silica gel 2 (SG2) fraction inhibited 60% of the HeLa cell proliferation. The IC50 was 154 microM equiv of (+)-catechin of the 100% methanol crude extract on HaCaT cells. Toyopearl fractions TP4 and TP6 significantly inhibited HaCaT cell proliferation, but the silica gel fractions did not have a significant effect. The 100% methanol crude extract (35 microg of dry material/mL) decreased the number of HeLa cells in the G0/G1 phase from 68.9% (for control cells) to 51.4% (for treated cells) and increased apoptosis (2.9 and 21.2% for control and treated cells, respectively). The results indicated that black Jamapa beans could be a source of polyphenolic compounds, which have an inhibitory effect toward HeLa cancer cells but are less aggressive on HaCaT premalignant cells.