Octadecylsilyl Research Articles

Preparation of monolithic silica HPLC columns with truss-structured skeletons and embedded surfactant-templated mesopores

AbstractMonolithic macro/mesoporous silica gels have been prepared via a sol-gel process using triblock copolymer Pluronic P123 (EO20PO70EO20) as a structure-directing agent. In this synthesis, P123 not only induces phase separation to form macroporous structure but also acts as a supramolecular template to form mesopores with precisely controlled shape and size. Obtained was a monolithic silica composed of continuous truss-like columnar skeletons in which cylindrical mesopores are arranged in a 2D-hexagonal symmetry. These monolithic silica gels have extremely high porosity approaching 90% and exhibited high specific surface area and sharp pore size distribution as revealed by N2 sorption measurements. Combinations of the initial composition and the post-gelation treatment on wet gels allowed the control of physical properties of meso- and macropore structures. The monolithic HPLC columns prepared using these silica gels surface-modified by ODS (octadecylsilyl) ligands gave as many as 140,000 theoretical plates/m for the separation of alkylbenzenes in a reversed-phase mode. Very weak dependence of height equivalent to theoretical plate, H, on the mobile phase velocity was also recognized in comparison with conventional particle-packed columns. Graphical Abstract

Two new pinophol derivatives from endophytic fungus Penicillium herquei JX4 hosted in Ceriops tagal

An OSMAC strategy was used to study secondary metabolites and anti-inflammatory activities of the endophytic fungus Penicillium herquei JX4 hosted in Ceriops tagal. The PDB ferment of fungus P. herquei JX4 was isolated, purified, and identified by using silica gel column chromatography, gel column chromatography, octadecylsilyl(ODS) column chromatography, and semi-preparative high-performance liquid chromatography. Two new pinophol derivatives, pinophol H(1) and pinophol I(2) were isolated and identified, and they were evaluated in terms of the inhibitory activities against the nitric oxide(NO) production induced by lipopolysaccharide(LPS) in mouse macrophage RAW264.7 cells. The results showed that compound 1 had significant inhibitory activity on NO production, with an IC_(50) value of 8.12 μmol·L~(-1).

Chemical constituents from stems and leaves of Artocarpus tonkinensis and their inhibitory effects on proliferation of synovioblasts in vitro

The chemical constituents from the stems and leaves of Artocarpus tonkinensis in Artocarpus of Moraceae were systematically studied by means of silica gel, octadecylsilyl(ODS), and Sephadex LH-20 gel column chromatographies, as well as preparative high-performance liquid chromatography(Pre-HPLC) and a variety of chromatographic separation techniques. The spectral data and physicochemical properties of the compounds were obtained from separation and compared with those of the compounds reported in the literature. As a result, 11 compounds isolated from the 90% ethanol extract of the stems and leaves of A. tonkinensis were identified as artocatonkine(1), 5,6,7,4'-tetramethoxyflavone(2), apigenin-4'-O-β-D-glucoside(3), rayalinol(4), psorachalcone A(5), 4-ketopinoresinol(6), ficusesquilignan B(7), pinnatifidanin AI(8), pinnatifidanin A(9), O-methylmellein(10), and trans-4-hydroxymellein(11). Among these compounds, compound 1 was a new prenylated flavone, and compounds 2-11 were isolated from the plants belonging to the genus Artocarpus for the first time. Furthermore, all compounds 1-11 were evaluated for their anti-rheumatoid arthritis activities, and the MTS method was used to measure their inhibitory effects on the proliferation of synovioblasts in vitro. The results of activity evaluation showed that flavonoid compounds 1-3, 5, and lignan compounds 8 and 9 displayed significant anti-rheumatoid arthritis activities, showing the IC_(50) values in inhibiting the proliferation of synovioblasts MH7A from(6.38±0.06) μmol·L~(-1) to(168.58±0.28)μmol·L~(-1).

Development of an HPLC device with water/acetonitrile with NaCl mixed solution that induces a phase-separation multiphase flow as the eluent in the separation column.

We developed a novel HPLC device where the phase-separation multiphase flow worked as the eluent in the separation column by using a water/acetonitrile/ethyl acetate triple mixed solution as a dual-phase-separation solution. Dual-phase-separation solutions form a phase-separation multiphase flow in a microscopic space. The new separation mechanism in the HPLC is called phase-separation mode. In this study, we used water and acetonitrile with NaCl mixed solution as a dual-phase-separation solution instead of the triple mixed solution. Octadecylsilyl (ODS)-modified particle- and porous silica particle-packed separation columns were united with the HPLC device for phase-separation mode caused by phase-separation multiphase flow. NA (1-naphthol) and NDS (2,6-naphthalenedisulfonic acid) were analyzed by the device as model sample. Using the water and acetonitrile with NaCl mixed solution at the solvent volume ratio of 5:5, NA and NDS were not separated on either column at 25°C. On the other hand, they were separated with the order NDS and NA on the ODS column and separated with the order NA and NDS on the silica column in phase-separation mode at 0°C. We discuss the separation mechanism of phase-separation mode using the water and acetonitrile with NaCl mixed solution at 0°C.

Analysis of Urinary Amino Acids by High-Performance Liquid Chromatography with Fluorescence Detection Using 2,3-Naphthalenedicarboxaldehyde as Fluorescence Derivatization Reagent

Amino acids are involved in various chemical reactions in vivo, and changes in several amino acids in urine are related to certain disease states. Therefore, developing an efficient method to analyze the amino acids in urine is useful in the timely diagnosis of diseases. In this study, we developed a high-performance liquid chromatography (HPLC) fluorescence method for the quantitative analysis of urinary amino acids using the fluorescence derivatization reagent 2,3-naphthalenedicarboxaldehyde (NDA). NDA was selected because it does not require heating for the reaction and can react within a short time, rendering its use in clinical settings feasible. The reaction temperature, reaction time, and other derivatization conditions were optimized, and the reaction was found to be completed in 5 min at 25 °C. The separation of NDA–amino acids was investigated on an octadecylsilyl (ODS) column under gradient conditions. The mobile phase was a mixture of water–acetonitrile–trifluoroacetic acid. Eighteen NDA–amino acids (histidine (His), arginine (Arg), asparagine (Asn), glutamine (Gln), citrulline (Cit), serine (Ser), aspartic acid (Asp), threonine (Thr), glutamic acid (Glu), glycine (Gly), tyrosine (Tyr), alanine (Ala), tryptophan (Trp), valine (Val), phenylalanine (Phe), isoleucine (Ile), leucine (Leu), and 5-aminovaleric acid (internal standard)) were separated within 100 min under optimal conditions. The calibration curves showed good linearity in the range of 0.25–25 pmol per injection with correlation coefficients of >0.998. The limits of quantification for NDA–amino acids were 16.7–74.7 fmol. The developed analytical method was applied to a human urine sample and 16 amino acids (His, Arg, Asn, Gln, Cit, Ser, Thr, Glu, Gly, Tyr, Ala, Trp, Val, Phe, Ile, and Leu) were quantified. The urinary amino acid concentrations were 5–960 μM. Urinary amino acid analysis using this method is expected to be clinically applicable as a novel biomarker for diseases affecting the bladder, urinary tract, and kidneys.

Chemical constituents from fruits of Morinda citrifolia and their inhibitory effects on proliferation of synoviocytes in vitro

The chemical constituents from the fruits of Morinda citrifolia were systematically explored by chromatographic fractionation methods including silica gel, octadecylsilyl(ODS) gel, Sephadex LH-20 gel, and preparative high performance liquid chromatography(pre-HPLC). The chemical structures of all isolated compounds were identified on the basis of their physicochemical properties, spectroscopic analyses, as well as the comparisons of their physicochemical and spectroscopic data with the reported data in literature. As a result, 22 isolated compounds from the 90% ethanol extract of the fruits of M. citrifolia were identified, which were moricitritone(1), 2'-deoxythymidine(2), cyclo-(L-Pro-L-Tyr)(3), methyl-5-hydroxy-2-pyridinecarboxylate(4), methyl pyroglutamate(5), bisbenzopyran(6), epipinoresinol(7), 3, 3'-bisdemethyl pinoresinol(8), 3, 3'-bisdemethyltanegool(9), trimesic acid(10), crypticin B(11), kojic acid(12), vanillic acid(13), protocatechoic acid(14), 5-hydroxymethyl furfural(15), blumenol A(16), 1-O-(9Z, 12Z-octadecadienoyl) glycerol(17), mucic acid dimethylester(18), methyl 2-O-β-D-glucopyranosylbenzoate(19), 2-phenylethyl-O-β-D-glucoside(20), scopoletin(21), and quercetin(22). Among them, compound 1 was a new pyrone derivative, compounds 2, 4-7, 10-12, and 17 were isolated from the plants belonging to Morinda genus for the first time, and compound 18 was obtained from M. citrifolia for the first time. Moreover, on the basis of testing the activities of all isolated compounds on inhibiting the proliferation of synovial fibroblasts in vitro by MTS assay, the anti-rheumatoid arthritis activities of all isolated compounds were initially evaluated. The results showed that compounds 1-6, 9, 19, and 20 exhibited remarkable anti-rheumatoid arthritis activities, which displayed the inhibitory effects on the proliferation of MH7A synovial fibroblast cells with the IC_(50) values in the range of(3.69±0.08) to(168.96±0.98) μmol·L~(-1).

High-Purity Fucoxanthin Can Be Efficiently Prepared from Isochrysis zhangjiangensis by Ethanol-Based Green Method Coupled with Octadecylsilyl (ODS) Column Chromatography.

The exploitation of new economically valuable microalgae as a sustainable source of minor high-value products can effectively promote the full utilization of microalgae. The efficient preparation of minor products from microalgae remains the challenge, owing to the coexistence of various components with a similar polarity in the microalgae biomass. In this study, a novel approach based on the sustainable-oriented strategy for fucoxanthin (FX) production was proposed, which consisted of four steps, including the culture of microalga, ethanol extraction, ODS column chromatography, and ethanol precipitation. The high-purity FX (around 95%) was efficiently obtained in a total recovery efficiency of 84.28 ± 2.56%. This study reveals that I. zhangjiangensis is a potentially promising feedstock for FX production and firstly provides a potentially eco-friendly method for the scale-up preparation of FX from the microalga I. zhangjiangensis.

Weed Suppression and Molecular Mechanisms of Isochlorogenic Acid A Isolated from Artemisia argyi Extract via an Activity-Guided Method.

Allelopathy is considered an environmentally friendly and resource-conserving approach to weed control because allelochemicals degrade easily and cause less pollution than traditional chemical herbicides. In this study, the allelopathic active constituents of Artemisia argyi were elucidated by activity-guided isolation and ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). First, a crude extract prepared in water was fractionated using macroporous resin D101 to obtain three fractions (Fr.A-C). Combined with the allelopathic activity assay on Setaria viridis and Portulaca oleracea, Fr.C was determined to be the most active fraction. We identified 14 compounds in the active fraction (Fr.C) using UPLC-QTOF-MS, including 13 phenolic compounds. Accordingly, phenolic components have been suggested as the main allelochemicals in A. argyi. Thereafter, Fr.C was further isolated by octadecylsilyl (ODS) chromatography to obtain eight subfractions (Fr.C-1-Fr.C-8). Finally, isochlorogenic acid A (ICGAA) was purified from Fr.C-3 by semipreparative liquid chromatography, which was detected in the growth environment of A. argyi. Furthermore, we evaluated the allelopathic effects of ICGAA on six weeds from different families and genera for the first time. The results showed that ICGAA is a novel allelochemical with broad herbicidal activity. In addition, we analyzed the inhibitory effect and molecular mechanism of ICGAA on the growth of S. viridis seedlings. Optical microscopy and transmission electron microscopy (TEM) revealed the degradation of membrane structures and organelles after ICGAA treatment. Transcriptome and real-time polymerase chain reaction (RT-qPCR) analysis showed that ICGAA inhibited the growth of weeds mainly by inhibiting the diterpenoid biosynthesis pathway (especially gibberellins, GAs). The decrease of gibberellin (GA) contents after ICGAA treatment also confirmed these results. In brief, this study provides new material sources and theoretical support for developing biological herbicides for agroecosystems.

Rapid detection of α-amanitin and β-amanitin in rat plasma by ultra-performance liquid chromatography-tandem mass spectrometry and its application to the toxicokinetic study of Lepiota brunneoincarnata.

Lepiota brunneoincarnata is a well-known poisonous mushroom and is responsible for fatal mushroom poisoning cases worldwide. α-Amanitin and β-amanitin are the main amatoxin compounds of Lepiota brunneoincarnata. However, there are no published toxicokinetic studies of Lepiota brunneoincarnata. To study the toxicokinetics of Lepiota brunneoincarnata, we developed an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determination of α-amanitin and β-amanitin in rat plasma. UPLC-MS/MS analyses were performed with a triple quadrupole mass spectrometer in positive-ion mode. The sensitivity of α-amanitin and β-amanitin detection was increased by inhibiting the production of [M + Na]+ adducts. α-Amanitin and β-amanitin were separated and quantified on an UPLC octadecyl silyl column in only 2.5min. The linear ranges were 3.0-3000ng/mL for α-amanitin and 1.8-1800ng/mL for β-amanitin with a correlation coefficient r > 0.99 for both analytes. The lower limit of quantification of 3.0ng/mL for α-amanitin and 1.8ng/mL for β-amanitin was achieved using only 50 μL of rat plasma. The accuracy of α-amanitin and β-amanitin was between - 9.5 and 7.0% with the precision ranged from 2.2 to 12.5%. The developed method was then applied for Lepiota brunneoincarnata toxicokinetic study after intravenous administration of Lepiota brunneoincarnata extracts. Establishing UPLC-MS/MS method for quantifying amanitines in rat plasma successfully enabled toxicokinetic study of Lepiota brunneoincarnata extracts.

Isolation and Purification of Fucoxanthin from Brown Seaweed Sargassum horneri Using Open ODS Column Chromatography and Ethanol Precipitation.

As an abundant marine xanthophyll, fucoxanthin (FX) exhibits a broad range of biological activities. The preparation of high-purity FX is in great demand, however, most of the available methods require organic solvents which cannot meet the green chemistry standard. In the present study, a simple and efficient purification approach for the purification of FX from the brown seaweed Sargassum horneri was carried out. The FX-rich ethanol extract was isolated by octadecylsilyl (ODS) column chromatography using ethanol–water solvent as a gradient eluent. The overwhelming majority of FX was successfully eluted by the ethanol–water mixture (9:1, v/v), with a recovery rate of 95.36%. A parametric study was performed to optimize the aqueous ethanol precipitation process by investigating the effects on the purity and recovery of FX. Under the optimal conditions, the purity of FX was 91.07%, and the recovery rate was 74.98%. Collectively, the eco-friendly method was cost-efficient for the purification of FX. The developed method provides a potential approach for the large-scale production of fucoxanthin from the brown seaweed Sargassum horneri.

Predicting Pharmacokinetic Properties of Potential Anticancer Agents via Their Chromatographic Behavior on Different Reversed Phase Materials.

The Quantitative Structure-Activity Relationship (QSAR) methodology was used to predict biological properties, i.e., the blood–brain distribution (log BB), fraction unbounded in the brain (fu,brain), water-skin permeation (log Kp), binding to human plasma proteins (log Ka,HSA), and intestinal permeability (Caco-2), for three classes of fused azaisocytosine-containing congeners that were considered and tested as promising drug candidates. The compounds were characterized by lipophilic, structural, and electronic descriptors, i.e., chromatographic retention, topological polar surface area, polarizability, and molecular weight. Different reversed-phase liquid chromatography techniques were used to determine the chromatographic lipophilicity of the compounds that were tested, i.e., micellar liquid chromatography (MLC) with the ODS-2 column and polyoxyethylene lauryl ether (Brij 35) as the effluent component, an immobilized artificial membrane (IAM) chromatography with phosphatidylcholine column (IAM.PC.DD2) and chromatography with end-capped octadecylsilyl (ODS) column using aqueous solutions of acetonitrile as the mobile phases. Using multiple linear regression, we derived the statistically significant quantitative structure-activity relationships. All these QSAR equations were validated and were found to be very good. The investigations highlight the significance and possibilities of liquid chromatographic techniques with three different reversed-phase materials and QSARs methods in predicting the pharmacokinetic properties of our important organic compounds and reducing unethical animal testing.

Urinary free metanephrines measurement in dogs with adrenal gland diseases using a new simple liquid chromatography tandem mass spectrometry method.

Measurement of urinary metanephrines in spot samples is used for the diagnosis of canine pheochromocytoma (PC). We describe a simple analytical method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) for measuring free metanephrine (MN) and normetanephrine (NMN) in spot urine samples. Using the developed method, we evaluated the stability of urinary free-MN and free-NMN at various storing conditions. In addition, we assessed the feasibility of urinary free-MN and -NMN measurement for diagnosing PC. Urine samples were mixed with stable isotope internal standards and thereafter purified by ultrafiltration. The purified samples were analyzed by LC-MS/MS in the multiple reaction monitoring mode after separation on a multimode octa decyl silyl column. The coefficient of variation of free-MN and -NMN measurement was 7.6% and 5.5%, respectively. The linearity range was 0.5–10 µg/l for both analytes. Degradation was less than 10% for both analytes under any of the storage conditions. The median free-NMN ratio to creatinine of 9 PC dogs (595, range 144–47,961) was significantly higher (P<0.05) than that of 13 dogs with hypercortisolism (125, range 52–224) or 15 healthy dogs (85, range 50–117). The developed method is simple and may not require acidification of spot urine. The results of this preliminary retrospective study suggest that the measurement of urinary free metanephrines is a promising tool for diagnosing canine PC.

Effects of Residual Silanol on Solid Phase Extraction of Organic Compounds to Octadecylsilyl Silica.

Batchwise equilibrium study was carried out on the retention of nonpolar and polar organic compounds to octadecylsilyl (ODS) silicas of different properties at atmospheric pressure. While nonpolar compounds were retained only by distribution on the ODS phase, polar compounds were retained by both distribution and Langmuir-type adsorption on residual silanol. Retention on ODS silica with more silanol proceeded at a higher rate than retention on ODS silica with less silanol and was reversible on this solid phase extraction time-scale. An increase in surface density of ODS decreased the distribution constant, due to a decrease in fraction of ODS functioning as an extracting medium and also decreased the saturated adsorption amount, due to reductions of the residual silanol and the functioning ODS. The ODS silica with the lowest ODS density showed a distribution constant 31 times higher and a saturated adsorption amount 27 times higher than the ODS silica with the highest ODS density. On the other hand, because the interaction between the organic part and the ODS group introduced at higher density is strengthened, the adsorption constant is increased by about 5 times compared to the low density ODS silica. The electronic effects of substituents to nitrogen- and oxygen-containing compounds on retention were discussed. In conclusion, ODS silica with an appreciable amount of residual silanol is superior for solid phase extraction.

A Potential Anti-cancer Compound Separated from the Chloroform Extract of the Chinese Medicine Formula Shenqi San.

This study examined anti-cancer compounds present in the chloroform extract of the Chinese medicine formula Shenqi San (CE-SS). Silica gel column chromatography, Sephadex LH-20, octadecylsilyl (ODS) column chromatography, and high performance liquid chromatography (HPLC) were used to separate the compounds from CE-SS. The structural formulas of the separated compounds were determined using 1D 1H and 13C experiments as well as high resolution electrospray ionization mass spectroscopy (HRESIMS). The corresponding results were compared with the reported literature data. A total of six compounds were separated and their structures were identified on the basis of corresponding spectroscopic and physico-chemical properties. They were Saikogenin F (I), Prosaikogenin D (II), Prosaikogenin F (III), β-sitosterol (IV), 3β,16β,23-trihydroxy-13,28-epoxyurs-11-ene-3-O-β-D-glucopyranoside (V), and methyl ursolic acid (VI). The separated compounds were evaluated in vitro for their inhibitory ability against the proliferation of A549 cells via MTT assay. Apoptosis was investigated using Annexin V-FITC/propidium iodide (PI) by flow cytometry. Apoptosis-associated proteins were examined by Western blotting. All the compounds were observed to have inhibitory activities against the proliferation of A549 cells to different degrees. Flow cytometry showed that compound V increased the proportion of apoptotic A549 cells in a dose-dependent manner. Western blotting showed that compound V increased the expression of Bax, cleaved-caspase-3, cleaved-caspase-9 and cleaved-poly ADP-ribose polymerase (PARP), and decreased the expression of Bcl-2. These results indicated that compound V featured a significant inhibitory effect on A549 cells when compared with other compounds, and it may be considered a potential drug against cancers.

Roles of Residual Silanol in Solid Phase Extraction of Copper to Octadecylsilyl Silica in the Presence of Acetylacetone.

Batchwise studies have demonstrated that the retention of acetylacetone (Haa) from an aqueous phase in non-endcapped octadecylsilyl (ODS) silica with silanol intentionally left (NEC) is stronger than the retention in endcapped ODS silica under ambient pressure, due to the enhanced wettability and the contribution of adsorption to silanol (-SiOH) as well as of the distribution into the ODS phase. Equilibrium analysis on solid phase extraction (SPE) of copper ion with Haa to NEC has indicated the adsorption of 1:1 species by the proton replacement reaction with silanol to give [-SiOCu(aa)] at relatively low Haa concentrations and the adsorption of [Cu(aa)2] to silanol, as well as the distribution of [Cu(aa)2] into the ODS phase. These adsorbed and distributed species of the same composition could be differentiated by ESR spectroscopy. The advantages of residual silanol in SPE of metal ions are discussed.

Bioactive triterpenoid saponins from the tubers of Hemsleya amabilis Diels

Five new cucurbitane-type triterpenoid saponins Xuedanosides A-E (1–5) were isolated from the medicinal plant Hemsleya amabilis Diels by silica gel column, octadecylsilyl (ODS) column, and pre-HPLC techniques. Their structures were determined by spectroscopic analysis and examined alongside existing data from prior studies. Separated compounds were evaluated for their cytotoxic activity in HeLa, HCT-8, MCF-7 and HepG2 human cancer cell lines, and compounds 1 and 2 showed significant effects against HeLa cells with IC50 values of 3.21 and 8.57 μM, respectively.

Stability kinetics of fusidic acid: Development and validation of stability indicating analytical method by employing Analytical Quality by Design approach in medicinal product(s)

A simple, rapid, accurate, reproducible and sensitive reverse phase HPLC method for the estimation of fusidic acid (FA) by means of Analytical Quality by Design (AQbD) was the aim of the present study. Initially, the vital pre-requisites for AQbD like analytical method target profile and critical analytical attributes (CAAs) like theoretical plates, tailing factor and percent assay were defined. An octadecyl silyl silica C18 column with a packing size of 5 μm was employed and the detection was performed at 235 nm using UV-detector. The separation was performed with isocratic elution employing mixture of methanol: acetonitrile (5: 95, v/v) and an aqueous phase with pH of 2.8 containing 0.1% orthophosphoric acid in the ratio of 60: 40 (v/v). Ishikawa fish-bone diagram provided the basis of the variation in CAAs with various inputs. Taguchi Design was selected as the initial screening design to select critical method parameters (CMPs) affecting method development and Central Composite Design (CCD) was further applied for systematic optimization of chromatographic method by evaluating CAAs. Crucial parameters viz. limit of detection, limit of quantification, specificity, linearity and sensitivity were employed to validate the method in accordance with the ICH guidelines. Stress degradation studies were performed and the developed method was able to successfully differentiate the degraded products from the parent drug, that too in a topical gel. In conclusion, the findings of the present study validated the utility of AQbD in the systematic design of a liquid chromatographic method with fine sensitivity for FA estimation in medicinal products.

Determination of Short-Chain Fatty Acids in Mouse Feces by High-Performance Liquid Chromatography Using 2-Nitrophenylhydrazine as a Labeling Reagent.

It has been suggested that imbalances in gut microbiota are related to diseases associated with metabolism, the central nervous system, etc. Therefore, analysis of short-chain fatty acids (SCFAs) produced by gut microbiota is very important as an indicator of causation, demonstrating the effects on the host due to changes in the gut microbiota. We developed a HPLC method for the determination of SCFAs in mouse feces. After homogenization, the SCFAs in mouse feces and 2-ethylbutyric acid (internal standard) were derivatized with 2-nitrophenylhydrazine (2-NPH) in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. The 2-NPH derivatives of SCFAs and the internal standard were separated on a reversed-phase column (octadecyl silyl column) by gradient elution using phosphoric acid (pH 2.5)-acetonitrile at 50°C and detected by absorbance measurement at 400 nm. The recovery of the method was 90-115%, with a precision (relative standard deviation) of 1.3-7.7%. The determination of SCFAs by the present method can provide useful information for biological and clinical research.

Isolation of Sphingoid Bases from Starfish Asterias amurensis Glucosylceramides and Their Effects on Sphingolipid Production in Cultured Keratinocytes.

Starfish Asterias amurensis produces sphingoid bases d18:3, 9-methyl-d18:3 (9Me-d18:3), and d22:2, which possess unique structural features. In this study, sphingoid bases prepared from A. amurensis glucosylceramides displayed unexpected elution behaviors from a general octadecyl silyl high-performance liquid chromatography (HPLC) column. For separation and isolation, sphingoid bases were fractionated by octadecyl silyl HPLC after N-acetylation, yielding d18:3, 9Me-d18:3, and two d22:2 isomers. To compare the biological activities of individual sphingoid bases, their effects on sphingolipid production in normal human keratinocytes were evaluated. Treatment with sphingoid bases increased the content of ceramides, glucosylceramides, and sphingomyelins in keratinocytes. Moreover, ceramides, which contain saturated ultra-long-chain fatty acids (C30-34), were significantly increased by treatment with d18:3, but not with other A. amurensis sphingoid bases. The mRNA level of the early differentiation marker keratin 10 was markedly decreased and sphingolipid synthesis-related genes were slightly increased in keratinocytes exposed to A. amurensis-derived d18:3, 9Me-d18:3, and d22:2 isomers. These results suggest that A. amurensis-derived sphingoid bases induce differentiation to varying degrees, sphingolipid production depends on their chemical structures, and d18:3 is the most promising functional sphingoid base.

1,3,5-Triazine tetrad-aza cyclophanes coated silica as a novel stationary phase for high performance liquid chromatography

A new stationary phase (TTCPSP) has been prepared by covalently bonding 1,3,5-triazine tetrad-aza cyclophanes (TTCP) onto silica gel using 3-aminopropyl triethoxysilane as the coupling reagent. The stationary phase developed in this way was characterized by IR spectroscopy, elemental analysis and thermogravimetric analysis. The chromatographic performance and retention mechanisms of the new stationary phase were validated and compared with octadecylsilyl (ODS) stationary phases using a variety of compounds including monosubstituted benzenes, polycyclic aromatic hydrocarbons (PAHs) and flavonoids. The results indicate that the 1,3,5-triazine tetrad-aza cyclophanes (TTCPSP) stationary phase addresses solutes with multiple interactions, such as hydrophobic, hydrogen bonding, π-π, and inclusion interactions. TTCPSP, which shows strong retention ability to compounds containing OH, NH2 or phenyl conjugate groups, is promising as a type of solid phase extraction sorbent.