High-performance Size-exclusion Chromatography Analysis Research Articles

Molecular-level transformations of biomass burning-derived water-soluble organic carbon during dark aqueous OH oxidation: Insights from absorption, fluorescence, high-performance size exclusion chromatography and high-resolution mass spectrometry analysis

Biomass burning (BB) releases large amounts of water-soluble organic carbon (WSOC), which would undergo heterogenous oxidation processes that induce transformations in both molecular structures and compositions within BB WSOC. This study designed an aqueous oxidation initiated by OH radicals in the absence of light for WSOC extracted from smoke particles generated by burning of corn straw and fir wood. The BB WSOC was comprehensively characterized using a combination of UV–visible spectra, excitation-emission matrix fluorescence in conjunction with parallel factor analysis (EEM-PARAFAC), high-performance size exclusion chromatography (HPSEC), and high-resolution mass spectrometry (HRMS) analyses. Over the course of oxidation, both chromophores and fluorophores exhibited gradual decreases. Moreover, EEM-PARAFAC revealed a preferential degradation of larger-sized protein-like/phenol-like organic matters, accompanied by the accumulation and/or formation of humic-like substances in aged BB WSOC. HPSEC analysis showed notable changes in molecular weight (MW) distributions for both types of BB WSOC during oxidation. Specifically, high MW species (>1 kDa) displayed a tendency to form along with oxidation, possibly attributed to the formation of assemblies via intermolecular weak forces. After oxidation, evidence of CHO compound degradation and enrichment/formation of CHON compounds was observed for both types of BB WSOC. Remarkably, the resistant, degraded and produced molecules for BB WSOC were dominated by CHO (38–73 %) and lignin-like molecules (41–47 %), suggesting diverse responses to oxidation within these two groups. Furthermore, polyphenols experienced selective degradation, while CHON, aliphatic and poly-aromatic molecules tended to form during the oxidation process for both types of BB WSOC. In summary, this study provides a comprehensive understanding of the molecular-level transformations undergone by BB WSOC during dark aqueous OH oxidation. The findings significantly contribute to our insights into atmospheric evolution of BB WSOC, thereby playing a crucial role in accurately assessing their effects within climate models and informing policy decisions.

Mechanism and inhibition of abnormal chromatographic behavior of serotype type a inactivated foot and mouth disease virus in high-performance size-exclusion chromatography

High-performance size-exclusion chromatography (HPSEC) has been developed for the rapid and quantitative analysis of inactivated foot and mouth disease virus (FMDV) and adopted by regulatory agencies and vaccine manufacturers. However, strong non-specific adsorption of type A/AKT III FMDV was found on some batches of TSK G4000 SWXL column, which significantly affected the analysis accuracy. The adsorption mechanism was studied by investigating the charge and hydrophobicity of A/AKT III FMDV and another serotype O/Mya 98, as well as several model proteins, by zeta potential and hydrophobic interaction chromatography analysis. Adsorption was related to both the FMDV strain and column lots. Some specific amino acids residues on the A/AKT III FMDV surface may strongly interact with the column if the silica-based stationary phase was not completely diol-modified. Several amino acids and chaotropic salts were screened as additives in the mobile phase to suppress the non-specific adsorption of AKT III FMDV in HPSEC analysis. Results showed that adding 0.4 M of arginine (Arg), lysine (Lys), NaClO4, or NaSCN achieved 100% FMDV recovery and normal retention time. Suppression of interaction between FMDV and the backbone of the silica matrix through competitive binding with residues of FMDV or the matrix is considered as the main mechanism by which these four additives act as suppressors. The addition of Arg, NaClO4, or NaSCN led to an apparent decrease in the thermal dissociation temperature Tm of FMDV, whereas Lys slightly increased viral stability. Finally, the mobile phase comprising 0.4 M Lys was screened as optimum that allowed accurate quantification of both two serotypes of FMDV according to method validation; particularly, a relative standard deviation (RSD) < 5% was achieved for AKT III FMDV using three different lots of columns.

Acetylation modification improved the physicochemical properties of xyloglucan from tamarind seeds

Acetylation modification was conducted to improve the water-solubility and solution properties of xyloglucan from tamarind seeds (TSX). Three acetylated TSX with different degree of substitution (DS) were successfully prepared, and their structure and molecular parameters were investigated by FT-IR, NMR, and high-performance size exclusion chromatography (HPSEC). Further, the effects of acetylation on the thermal stability, solubility, and rheological properties of TSX were studied. Results showed that acetyl groups were mainly substituted at the O-6 position of terminal galactose with DS of 0.2, 0.47, and 0.36 for AC-2, AC-5, and AC-10, respectively. HPSEC analysis indicated that molecular weight of acetylated derivatives decreased slightly, and the solution conformation became more flexible as the DS increase. By comparing with TSX, the thermal stability, water-solubility, solution transmittance, and ζ-potential of acetylated TSX were significantly improved as the DS increase. In addition, rheological studies demonstrated that acetylation reduced the shear viscosity, but high DS of acetylation could induce the weak gelling property of TSX. In conclusion, acetylation modification could be applied to improve the physicochemical properties of TSX and promote its further application in food and pharmaceutical industries.

Physicochemical, rheological properties and in vitro hypoglycemic activities of polysaccharide fractions from peach gum

In this study, peach gum was sequentially extracted by water at 25 °C, 95 °C and 0.1 M NaOH, obtaining room temperature water-soluble (PG-WE), hot water-soluble (PG-HWE), and alkali-soluble (PG-AE) polysaccharide fractions. These three kinds of polysaccharide fractions exhibited a similar arabinogalactan structure according to FTIR spectrum and monosaccharide composition. However, their molecular weight and chain conformation were different based on high-performance size exclusion chromatography analysis, which resulted in different rheological behavior. PG-WE and PG-HWE presented non-Newtonian behavior, and the apparent viscosity of PG-WE was higher than that of PG-HWE at concentrations of 2.0 % and 3.0 % (w/w). Dynamic sweep tests showed that PG-HWE solutions behaved as viscous fluids, while PG-WE solutions tended to form gel-like structures at concentrations higher than 2 % (w/w). Furthermore, PG-WE showed significant in vitro inhibition against α-glucosidase activity in a dose-dependent manner and reduced the fluorescence of α-glucosidase through dynamic quenching mechanism.

Size exclusion chromatography using large pore size media induces adverse conformational changes of inactivated foot-and-mouth disease virus particles

Size exclusion chromatography (SEC) of biomacromolecules using large pore size media and long column are usually necessary to obtain a satisfactory separation. However, the SEC separation of inactivated foot and mouth disease virus (FMDV) was found to induce some subtle but important conformational changes of FMDV in a pore-size and column length dependent manner. Here three Sephacryl media including S-300 HR, S-400 HR, and S-500 HR were tested, whose pore sizes were smaller than, similar to, and larger than the FMDV particles, respectively. High performance size exclusion chromatography (HPSEC) analyses showed that the FMDV after all these three SEC processes had earlier retention time, compared with that before SEC, but had no detectable difference in particle integrity. Longer SEC column led to more significant peak shifting in subsequent HPSEC analysis of FMDV. Further analyses indicated the SEC using larger pore size media induced more remarkable conformational changes and decrease in thermostability of FMDV, as well as decrease in immunogenicity in animal test. Fluorescence probe diffusion study suggested compared to SEC by S300, the compactness of the viral capsid after SEC by S400 and S500 was decreased, possibly due to more shear-induced FMDV particle rotation and inter-particle collision inside the media pores, as well as their interactions with the pore walls of the media during flowing through the column. Finally, a stabilization strategy by appending 5 mM CaCl2 in mobile phase of SEC separation was proposed and proved to efficiently maintain the conformation of the FMDV.

Lignin/Carbohydrate Complex Isolated from Posidonia oceanica Sea Balls (Egagropili): Characterization and Antioxidant Reinforcement of Protein-Based Films.

A lignin fraction (LF) was extracted from the sea balls of Posidonia oceanica (egagropili) and extensively dialyzed and characterized by FT-IR and NMR analyses. LF resulted water soluble and exhibited a brownish-to-black color with the highest absorbance in the range of 250–400 nm, attributed to the chromophore functional groups present in the phenylpropane-based polymer. LF high-performance size exclusion chromatography analysis showed a highly represented (98.77%) species of 34.75 kDa molecular weight with a polydispersity index of 1.10 and an intrinsic viscosity of 0.15. Quantitative analysis of carbohydrates indicated that they represented 28.3% of the dry weight of the untreated egagropili fibers and 72.5% of that of LF. In particular, eight different monosaccharides were detected (fucose, arabinose, rhamnose, galactose, glucose, xylose, glucosamine and glucuronic acid), glucuronic acid (46.6%) and rhamnose (29.6%) being the most present monosaccharides in the LF. Almost all the phenol content of LF (113.85 ± 5.87 mg gallic acid eq/g of extract) was water soluble, whereas around 22% of it consisted of flavonoids and only 10% of the flavonoids consisted of anthocyanins. Therefore, LF isolated from egagropili lignocellulosic material could be defined as a water-soluble lignin/carbohydrate complex (LCC) formed by a phenol polymeric chain covalently bound to hemicellulose fragments. LCC exhibited a remarkable antioxidant activity that remained quite stable during 6 months and could be easily incorporated into a protein-based film and released from the latter overtime. These findings suggest egagropili LCC as a suitable candidate as an antioxidant additive for the reinforcement of packaging of foods with high susceptibility to be deteriorated in aerobic conditions.

Novel insights into impacts of the COVID-19 pandemic on aquatic environment of Beijing-Hangzhou Grand Canal in southern Jiangsu region

In 2020, a sudden COVID-19 pandemic unprecedentedly weakened anthropogenic activities and as results minified the pollution discharge to aquatic environment. In this study, the impacts of the COVID-19 pandemic on aquatic environment of the southern Jiangsu (SJ) segment of Beijing-Hangzhou Grand Canal (SJ-BHGC) were explored. Fluorescent component similarity and high-performance size exclusion chromatography analyses indicated that the textile printing and dyeing wastewater might be one of the main pollution sources in SJ-BHGC. The water quality parameters and intensities of fluorescent components (WT-C1(20) and WT-C2(20)) decreased to low level due to the collective shutdown of all industries in SJ region during the Spring Festival holiday and the outbreak of the domestic COVID-19 pandemic in China (January 24th to late February, 2020). Then, they presented a gradual upward trend after the domestic epidemic was under control. In mid-March, the outbreak of the international COVID-19 pandemic hit the garment export trade of China and consequently inhibited the production activities of textile printing and dyeing industry (TPDI) in SJ region. After peaking on March 26th, the intensities of WT-C1(20) and WT-C2(20) decreased again with changed intensity ratio until April 12th. During the study period (135 days), correlation analysis revealed that WT-C1 and WT-C2 possessed homology and their fluorescence intensities were highly positively correlated with conductivity and CODMn. With fluorescence fingerprint (FF) technique, this study not only excavated the characteristics and pollution causes of water body in SJ-BHGC, but also provided novel insights into impacts of the COVID-19 pandemic on production activities of TPDI and aquatic environment of SJ-BHGC. The results of this study indicated that FF technique was an effective tool for precise supervision of water environment.

Identification of textile wastewater in water bodies by fluorescence excitation emission matrix-parallel factor analysis and high-performance size exclusion chromatography

Identifying the causes of water body pollution is critical because of the serious water contamination in developing countries. The textile industry is a major contributor to severe water pollution due to its high discharge of wastewater with high concentrations of organic and inorganic pollutants. In this study, fluorescence excitation emission matrix-parallel factor (EEM-PARAFAC) analysis was applied to characterize textile industry wastewater and trace its presence in water bodies. The EEM spectra of textile wastewater samples collected from 12 wastewater treatment plants (WWTPs) revealed two characteristic peaks: Peak T1 (tryptophan-like region) and Peak B (tyrosine-like region). Two protein-like components (C1 and C2) were identified in the textile wastewater by PARAFAC analysis. The components identified from different textile WWTPs were considered identical (similarity >0.95). C1 and C2 were not sensitive to changes in pH, ionic strength, or low humic acid concentration (TOC < 4 mg/L). Therefore, C1 combined with C2 was proposed as a source-specific indicator of textile wastewater, which was further demonstrated by conducting high-performance size exclusion chromatography analysis. These results suggested that EEM-PARAFAC analysis is a reliable means of identifying textile wastewater pollution in water bodies and may also enable the identification of other industrial wastewater.

The Pro-oxidant Activity and Composition of Polar Compound Fractions in Used Deep-frying Camellia Seed Oil

We aimed to investigate the pro-oxidant activity of polar compounds in deep-frying camellia seed oil (CO) using the accelerated oxidation test, and also to analyze the fractions and distribution of its polar compounds using high performance size exclusion chromatography (HPSEC). Our results indicated that the addition of previously isolated polar compounds to four types of CO (purified refined, unpurified refined, purified crude, and unpurified crude) reduced the oxidation induction time, which suggested that these compounds were actively pro-oxidant. This result is critical for the safe storage of refined oil, and for the quality monitoring of frying oil. Our HPSEC analysis showed that used CO contained polar compounds (TGO, TGD, ox-TGM, DG, and FFA). After 40 h of deep frying, the polymerization products (TGO and TGD), oxidative products (ox-TGM), and hydrolytic products (DG and FFA) comprised 54.63%, 33.54%, and 15.14% of the total polar content, respectively, suggesting that the hydrolysis reaction during the deep frying was weak compared to thermal oxidation polymerization. Based on this result, in combination with our measurement of the concentration of total polar compounds (TPC, 27%) and triacylglycerol polymers (TGP, 10-16%), we postulate that the frying life of CO is 32 h.

Polysaccharides isolated from Hedyotis diffusa inhibits the aggressive phenotypes of laryngeal squamous carcinoma cells via inhibition of Bcl-2, MMP-2, and μPA

Hedyotis diffusa, a traditional Chinese herbal medicine, possesses anti-cancer, anti-oxidative, and anti-inflammatory effects. The aim of this study is to explore the anti-tumor potential of Hedyotis diffusa polysaccharides (HDP) in human larynx squamous carcinoma. High performance size-exclusion chromatography analysis indicated the homogeneous nature of HDP. Total carbohydrate content in HDP was 97.3%, without contamination of protein and nucleic acid. HDP suppressed the proliferation of Hep2 human larynx squamous carcinoma cells in a time- and dose-dependent manner. Cell cycle analysis revealed that exposure to HDP (400μg/ml) caused a G0/G1 cell cycle arrest. Moreover, treatment with HDP for 24h induced a significant apoptosis of Hep2 cells, which was accompanied by increased cleavage of caspase-3, caspase-8, and caspase-9 and reduced expression of Bcl-2 protein. Additionally, HDP inhibited cell migration and suppressed the expression of MMP-2 and μPA. In conclusion, HDP shows suppressive effects against the aggressive phenotypes of human larynx squamous carcinoma cells and may have therapeutic potential for this malignancy.

Unraveling the size‐dependent optical properties of dissolved organic matter

AbstractThe size‐dependent optical properties of dissolved organic matter (DOM) from four Swedish lakes were investigated using High Performance Size Exclusion Chromatography (HPSEC) in conjunction with online characterization of absorbance (240–600 nm) and fluorescence (excitation: 275 nm, emission: 300–600 nm). The molecular size of chromophoric DOM (CDOM) was consistently higher than that of fluorescent DOM (FDOM), with an average difference of 0.37 kDa. The relative abundance of FDOM vs. CDOM ranged from 0.3 to 0.7 across lakes, and increased with decreasing average molecular size. Across sites, the CDOM spectral slopes of the large molecular size fraction were highly similar while the low molecular size fraction differed and contributed to different bulk spectral slopes. Our results indicate structural congruence of high molecular size DOM across systems while lake trophic status determined the characteristics of the low size range. Furthermore, the combination of HPSEC and parallel factor analysis (HPSEC‐PARAFAC2) allowed the decomposition of DOM fluorescence chromatograms. Three humic‐like components and one protein‐like component with broadly overlapping molecular size distributions were identified. This overlap provides further evidence for the supramolecular assembly hypothesis since fluorophores, as revealed by PARAFAC2, occur in aggregates of overlapping molecular size. Our results further suggest a link between the molecular size of these fluorophores and the associated supramolecular assemblies. This study demonstrates the potential for HPSEC and novel mathematical approaches to provide unprecedented insights into the relationship between optical and chemical properties of DOM in aquatic systems.

Elucidating Adsorptive Fractions of Natural Organic Matter on Carbon Nanotubes.

Natural organic matter (NOM) is a heterogeneous mixture of organic compounds that is omnipresent in natural waters. To date, the understanding of the adsorption of NOM components by carbon nanotubes (CNTs) is limited because of the limited number of comprehensive studies in the literature examining the adsorption of NOM by CNTs. In this study, 11 standard NOM samples from various sources were characterized, and their adsorption behaviors on four different CNTs were examined side-by-side using total organic carbon, fluorescence, UV-visible spectroscopy, and high-performance size-exclusion chromatography (HPSEC) analysis. Adsorption was influenced by the chemical properties of the NOM, including aromaticity, degree of oxidation, and carboxylic acidity. Fluorescence excitation-emission matrix (EEM) analysis showed preferential adsorption of decomposed and terrestrial-derived NOM compared to freshly produced and microbial-derived NOM. HPSEC analysis revealed preferential adsorption of fractions in the molecular weight range of 0.5-2 kDa for humic acids but in the molecular weight range of 1-3 kDa for all fulvic acids and reverse-osmosis isolates. However, the smallest characterized fraction (MW < 0.4 kDa) in all samples did not adsorb on the CNTs.

Tetra-detector size exclusion chromatography characterization of molecular and solution properties of soluble microbial polysaccharides from an anaerobic membrane bioreactor

Characterization of the molecular properties of soluble microbial products (SMP) is critical for understanding the membrane filtration and fouling mechanisms in anaerobic and aerobic membrane bioreactors (AnMBR & MBR). In this study, the distributions of the absolute molecular weight and intrinsic viscosity of SMP polysaccharides from an AnMBR were effectively determined by a high performance size exclusion chromatography (HPSEC) that was coupled with the refractive index (RI), diode array UV (DAUV), right and low angle light scattering (LS), and viscometer (Vis) detectors. Based on the tetra-detector HPSEC determined absolute molecular weights and intrinsic viscosity, a universal calibration relationship for the SMP polysaccharides was developed and the molecular conformations, average molecular weights, and hydrodynamic sizes of the SMP polysaccharides were also explored. Two factors which can be derived from the tetra-detector HPSEC analysis were proposed for the characterization of the viscous and osmotic pressure properties of the SMP polysaccharides. In addition, it was also extrapolated how to analyze the resistance characteristics of the concentration polarization layers formed in membrane filtration based on the molecular properties determined by the tetra-detector HPSEC analysis.

Identification of fouling materials in the microfiltration of seawater laden with marine algae

AbstractIn this study, fouling materials were identified in the microfiltration (MF) of seawater laden with marine algae. To this end, raw seawater spiked with either the dinoflagellate species without cell walls (Heterosigma akashiwo) or with cell walls (Prorocentrum micans) was filtered through a laboratory-scale MF system. Based on the results, polysaccharides, which were excreted by the marine algae, accumulated within the MF system and subsequently resulted in membrane fouling. Cell walls are closely related with polysaccharide excretion. The dinoflagellate species without cell walls released more polysaccharides than those with cell walls based on the unit surface area of the species. High-performance size exclusion chromatography analysis revealed that organic substances (1.1 and 22 kDa, molecular weight) were accumulated in the MF system. These organic substances could be the biofouling agents in MF systems during marine algal blooms.

High-performance size exclusion chromatography with a multi-wavelength absorbance detector study on dissolved organic matter characterisation along a water distribution system

This study examined the associations between dissolved organic matter (DOM) characteristics and potential nitrification occurrence in the presence of chloramine along a drinking water distribution system. High-performance size exclusion chromatography (HPSEC) coupled with a multiple wavelength detector (200–280nm) was employed to characterise DOM by molecular weight distribution, bacterial activity was analysed using flow cytometry, and a package of simple analytical tools, such as dissolved organic carbon, absorbance at 254nm, nitrate, nitrite, ammonia and total disinfectant residual were also applied and their applicability to indicate water quality changes in distribution systems were also evaluated. Results showed that multi-wavelength HPSEC analysis was useful to provide information about DOM character while changes in molecule weight profiles at wavelengths less than 230nm were also able to be related to other water quality parameters. Correct selection of the UV wavelengths can be an important factor for providing appropriate indicators associated with different DOM compositions. DOM molecular weight in the range of 0.2–0.5kDa measured at 210nm correlated positively with oxidised nitrogen concentration (r=0.99), and the concentrations of active bacterial cells in the distribution system (r=0.85). Our study also showed that the changes of DOM character and bacterial cells were significant in those sampling points that had decreases in total disinfectant residual. HPSEC-UV measured at 210nm and flow cytometry can detect the changes of low molecular weight of DOM and bacterial levels, respectively, when nitrification occurred within the chloraminated distribution system.

Combined use of resin fractionation and high performance size exclusion chromatography for characterization of natural organic matter

The number and complexity of natural organic matter (NOM) species limits identification of individual NOM compounds. The objective of this study was to employ several characterization techniques (resin fractionation, high performance size exclusion chromatography (HPSEC), and strategic UV254 absorbance) to samples from seven surface water sites in North America, and overcome the shortfalls of each tool. Resin fractionation indicated the samples were all high in hydrophobic acids (HOA), hydrophilic neutrals (HIN) and hydrophilic acids (HIA). Site B was the only site where HIAs were the highest NOM contributors. In the HPSEC analysis, each fraction exhibited a particular molecular weight (MW) range: 100–300 Da (HIN), 1-2 kDa (HOA), and the HIA fractions exhibited MWs between these two ranges. Strategic UV254 measurements were taken at two sites to supplement the HPSEC results, and determine the difference in UV absorbance per unit dissolved organic carbon (SUVA value). Most fractions showed SUVA values of approximately 5 L/mg-m; however, the hydrophilic bases and hydrophobic neutral fractions could not be accurately evaluated due to the very low DOC concentrations for these two fractions (< 0.2 mg/L). These methods are complimentary NOM characterization techniques, and the combined methodology addresses the analytical limits of each tool.

HPAEC-PAD quantification of Haemophilus influenzae type b polysaccharide in upstream and downstream samples

Due to the rapidly increasing introduction of Haemophilus influenzae type b (Hib) and other conjugate vaccines worldwide during the last decade, reliable and robust analytical methods are needed for the quantitative monitoring of intermediate samples generated during fermentation (upstream processing, USP) and purification (downstream processing, DSP) of polysaccharide vaccine components. This study describes the quantitative characterization of in-process control (IPC) samples generated during the fermentation and purification of the capsular polysaccharide (CPS), polyribosyl-ribitol-phosphate (PRP), derived from Hib. Reliable quantitative methods are necessary for all stages of production; otherwise accurate process monitoring and validation is not possible. Prior to the availability of high performance anion exchange chromatography methods, this polysaccharide was predominantly quantified either with immunochemical methods, or with the colorimetric orcinol method, which shows interference from fermentation medium components and reagents used during purification. Next to an improved high performance anion exchange chromatography-pulsed amperometric detection (HPAEC-PAD) method, using a modified gradient elution, both the orcinol assay and high performance size exclusion chromatography (HPSEC) analyses were evaluated. For DSP samples, it was found that the correlation between the results obtained by HPAEC-PAD specific quantification of the PRP monomeric repeat unit released by alkaline hydrolysis, and those from the orcinol method was high (R2=0.8762), and that it was lower between HPAEC-PAD and HPSEC results. Additionally, HPSEC analysis of USP samples yielded surprisingly comparable results to those obtained by HPAEC-PAD. In the early part of the fermentation, medium components interfered with the different types of analysis, but quantitative HPSEC data could still be obtained, although lacking the specificity of the HPAEC-PAD method. Thus, the HPAEC-PAD method has the advantage of giving a specific response compared to the orcinol assay and HPSEC, and does not show interference from various components that can be present in intermediate and purified PRP samples.

Polysaccharide of Boschniakia rossica induces apoptosis on laryngeal carcinoma Hep2 cells

The aim of this study was to explore the anti-tumor potential of a polysaccharide isolated from Boschniakia rossica (BRP) in Hep2 human larynx squamous carcinoma cells. High performance size-exclusion chromatography analysis showed that BRP was a homogeneous polysaccharide and had a molecular weight of 22kDa. Total carbohydrate content in BRP was determined to be 96.9%, without the presence of protein and nucleic acid. BRP suppressed the proliferation of Hep2 cells in a time- and dose-dependent manner. Cell cycle analysis revealed that exposure to BRP (200μg/ml) caused a G0/G1 cell cycle arrest in Hep2 cells. Moreover, treatment with BRP at 100–400μg/ml for 24h induced a significant apoptosis Hep2 cells compared to untreated control cells, as determined by flow cytometry with annexin-V/propidium iodide double staining. Additionally, BRP treatment promoted the cleavage of pro-caspase-3, pro-caspase-8, and pro-caspase-9, coupled with increased expression of death receptor DR5 and Bax and reduced expression of Bcl-2. Taken together, our data demonstrate that BRP shows potent anti-tumor activity in human larynx squamous carcinoma, largely through induction of G0/G1 cell cycle arrest and apoptosis. Activation of both mitochondria-mediated and death receptor-mediated apoptosis pathways is involved in the cytotoxicity of BRP.

Challenges in analysis of high-molar mass dextrans: Comparison of HPSEC, AsFlFFF and DOSY NMR spectroscopy

Dilute solutions of various dextran standards, a high-molar mass (HMM) commercial dextran from Leuconostoc spp., and HMM dextrans isolated from Weissella confusa and Leuconostoc citreum were analyzed with high-performance size-exclusion chromatography (HPSEC), asymmetric flow field-flow fractionation (AsFlFFF), and diffusion-ordered NMR spectroscopy (DOSY). HPSEC analyses were performed in aqueous and dimethyl sulfoxide (DMSO) solutions, while only aqueous solutions were utilized in AsFlFFF and DOSY. The study showed that all methods were applicable to dextran analysis, but differences between the aqueous and DMSO-based solutions were obtained for HMM samples. These differences were attributed to the presence of aggregates in aqueous solution that were less prevalent in DMSO. The study showed that DOSY provides an estimate of the size of HMM dextrans, though calibration standards may be required for each experimental set-up. To our knowledge, this is the first study utilizing these three methods in analyzing HMM dextrans.

A polysaccharide from Boschniakia rossica induces apoptosis in Hep2 human laryngeal squamous carcinoma cells

The aim of this study was to explore the anti-tumor potential of a polysaccharide isolated from Boschniakia rossica (BRP) in Hep2 human larynx squamous carcinoma cells. High performance size-exclusion chromatography analysis showed that BRP was a homogeneous polysaccharide and had a molecular weight of 22kDa. BRP suppressed the proliferation of Hep2 cells in a time- and dose-dependent manner. Cell cycle analysis revealed that exposure to BRP (200μg/ml) caused a G0/G1 cell cycle arrest in Hep2 cells. Moreover, treatment with BRP at 100-400μg/ml for 24h induced a significant apoptosis compared to untreated control cells. BRP treatment promoted the cleavage of pro-caspase-3, pro-caspase-8, and pro-caspase-9, coupled with increased expression of death receptor DR5 and Bax and reduced expression of Bcl-2. Taken together, our data demonstrate that BRP shows potent anti-tumor activity in human larynx squamous carcinoma, largely through induction of G0/G1 cell cycle arrest and apoptosis