Weak Cation Research Articles

High-throughput liquid chromatography tandem mass spectrometry assay as initial testing procedure for analysis of total urinary fraction.

In the recent years, a lot of effort was put into the development of multiclass initial testing procedures (ITP) to streamline analytical workflow in antidoping laboratories. Here, a high-throughput assay based on liquid chromatography-triple quadrupole mass spectrometry suitable for use as initial testing procedure covering multiple classes of compounds prohibited in sports is described. Employing a 96-well plate packed with 10 mg of weak cation exchange polymeric sorbent, up to 94 urine samples and their associated positive and negative controls can be processed in less than 3 h with minimal labor. The assay requires a 0.5-ml urine aliquot, which is subjected to enzymatic hydrolysis followed by solid phase extraction, evaporation, and reconstitution in a 96-well collection plate. With a 10-min run time, more than 100 analytes can be detected using electrospray ionization with polarity switching. The assay can be run nearly 24/7 with minimal downtime for instrument maintenance while detecting picogram amounts for the majority of analytes. Having analyzed approximately 28,000 samples, nearly 400 adverse analytical findings were found of which only one tenth were at or above 50% of the minimum required performance level established by the World Anti-Doping Agency. Compounds most often identified were stanozolol, GW1516, ostarine, LGD4033, and clomiphene, with median estimated concentrations in the range of 0.02-0.09 ng/ml (either as parent drug or a metabolite). Our data demonstrate the importance of using a highly sensitive ITP to ensure efficient antidoping testing.

Isoform 1 of Fibrinogen Alpha Chain Precursor is a Potential Biomarker for Steroid-Induced Osteonecrosis of the Femoral Head.

Early diagnosis is crucial to increase the chances of conservation treatment for patients with steroid-induced osteonecrosis of the femoral head (SIONFH). This study aimed to identify serum peptides as potential biomarkers to diagnose SIONFH. The serum proteome of 32 SIONFH patients and 24 healthy controls are analyzed using magnetic bead-based weak cation exchange (MB-WCX) and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS). Next, candidate biomarkers are identified using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Candidate biomarkers are then validated using ELISA and western blotting. 39 peaks are identified and the expression fold changes of seven peaks in the two groups are greater than 1.5. Three peaks (m/z: 1077.84Da; m/z: 1061.78Da; m/z: 1099.56Da) tend to be upregulated, while four peaks (m/z: 3973.92Da; m/z: 7766.53Da; m/z: 3957.31Da; m/z: 4212.02Da) tend to be down-regulated in SIONFH patients. The peak for a 1077.84Da peptide is identified as Isoform 1 of the Fibrinogen alpha chain precursor (FGA). ELISAs and western blot analyses reveal that the expression of FGA is significantly higher in SIONFH patients than healthy controls. FGA is overexpressed in SIONFH patients, and thus, is a novel potential biomarker for SIONFH.

Novel serum peptide model revealed by MALDI-TOF-MS and its diagnostic value in early bladder cancer.

Bladder cancer is the ninth most common cancer worldwide and has high morbidity and mortality. We aimed to search for potential serum peptide biomarkers and establish a diagnostic model for early bladder cancer. A total of 67 bladder cancer patients and 64 healthy volunteers were randomly divided into a training set and testing set 1. There were 30 hematuria patients used as testing set 2. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry based on weak cation exchange magnetic beads was used to obtain and analyze the serum peptide profiles between bladder cancer patients and healthy volunteers in the training set. Serum peptide diagnostic model through a k-nearest neighbor algorithm, was established and validated, and significantly differentially expressed protein biomarkers were ultimately identified. We constructed a diagnostic model containing five peptides (m/z 1954.9, m/z 2081.0, m/z 3938.3, m/z 3946.5, and m/z 4268.8). In the training set, the area under the curve (AUC) value of the five-peptide model was 0.923, and the sensitivity and specificity was 93.75% and 96.77%, respectively. In testing set 1, the sensitivity and specificity was 91.43% and 90.91%, respectively, and the specificity of testing set 2 was 73.33%. For early-stage bladder cancer, the sensitivity and specificity was 92.31% and 93.75%, respectively; the sensitivity of early low-grade bladder cancer was 90.00%; and the AUC value was 0.944. The five-peptide diagnostic model established in this study had high sensitivity and specificity, especially in the diagnosis of early bladder cancer, and could differentiate between healthy volunteers and hematuria patients.

Quantification of phenolic compounds in vegetable oils by mixed-mode solid-phase extraction isotope chemical labeling coupled with UHPLC-MS/MS

In the present work, a rapid, accurate and cost-effective method has been developed for the simultaneous quantification of phenolic compounds in oil using mixed-mode solid-phase extraction (SPE) coupled with chemical labeling UHPLC-MS/MS. Mix-mode SPE weak cation cartridges were selected to enrich and purify phenolic compounds in oil, and hydroxyl moiety was dansylation as stable-isotope internal standard. The major parameters that affected the extraction and chemical labeling efficiency were investigated, and the method was fully validated. The limit of quantifications and the limit of detections were 0.002 µg kg−1 ~ 0.10 µg kg−1 and 0.006 µg kg−1 ~ 0.30 µg kg−1, respectively. The recoveries were 61.2% ~ 129.3% with intra-day and inter-day precision less than 12%. The results for 38 rapeseed oils revealed that 14 phenolic compounds, including canolol, phenolic acids, phenolic alcohols, tyrosol and vanillin from trace levels to relatively high content.

Swelling deformation of Na-bentonite in solutions containing different cations

Investigation of the effect of salt solution on the swelling properties of compacted bentonite is of great importance for evaluation of the properties of behavior of engineering barrier in deep geological repository for disposal of high-level radioactive waste. In the present work, a multitude of swelling deformation tests were performed on sodic bentonite using NaCl, KCl, and CaCl2 solutions. It is revealed from the results that the swelling strains of the tested samples in variety of saline solutions follow the order of NaCl > KCl > CaCl2 at the concentration of 0.1 mol/L (M), whereas the order was NaCl > CaCl2 > KCl at 1.0 M concentration. The fractal em–pe relations for swelling deformation of Na-bentonite in different solutions were estimated, where em is the smectite void ratio at saturation, pe is effective stress incorporating osmotic suction depicting the effects of ionic concentration on swelling. In addition, the effect of the cation exchange is described using the smectite swelling coefficient K. The estimation values fit well with the experimental data. In NaCl solutions, the coefficient K is basically unchanged due to the weak cation exchange reaction. On the contrary, Ca2+ can much easily replace Na+ even at low concentrations and the CaCl2 solution exhibits the highest values of osmotic suction, the swelling coefficient and swelling deformation of the samples in the 0.1 M CaCl2 solution are smaller than that of samples in other 0.1 M solutions. However, at high concentrations, Na+ can be fully replaced by both Ca2+ and K+. The hydration energy of K+ is comparatively lower due to which the swelling coefficient of the samples in the 1.0 M KCl solution significantly decreased thereby resulting in least swelling deformation.

Electro-assisted regeneration of pH-sensitive ion exchangers for sustainable phosphate removal and recovery

Removal and recovery of phosphate from wastewater can minimize deleterious environmental impacts and supplement fertilizer supply. Hybrid anion exchangers (HAIX, with doped ferric oxide nanoparticles (FeOnp)) can remove phosphate from complex wastewaters and recover concentrated phosphate solutions. In this study, we integrate HAIX with a weak acid cation exchanger (WAC) to enrich phosphate and calcium in mild regenerants and precipitate both elements for recovery. We demonstrated an electro-assisted regeneration approach to avoid strong acid and base input. Based on demonstrated pH sensitivities of both materials, electrochemically produced mild electrolytes (pH 3 and pH 11), which are 100–1000 times less concentrated than typical regenerants, preserved 80% WAC and 50% HAIX capacities over five batch adsorption-regeneration cycles. FeOnp in HAIX facilitated regeneration due to pH sensitivity and their likely distribution on the resin particle surface, which reduced intraparticle diffusion path length. In column tests, repeatable phosphate removal (> 95%) from synthetic wastewater (3 mg P/L) was achieved with 20 kWh/kg P specific energy consumption. After removal, a similar 50% HAIX regeneration efficiency as batch experiments was achieved. In spent regenerant, more than 95% phosphorus was recovered as hydroxyapatite. This novel approach enhances ion exchange by minimizing chemical inputs.

Field validation of multifunctional ion exchange process for reverse osmosis pretreatment and phosphate recovery during impaired water reuse

Conventional reverse osmosis (RO) pretreatment hardly achieves multifunctionality for simultaneous membrane scaling prevention and nutrient recovery during impaired water reuse. To address the challenge, we probed a multifunctional ion exchange pretreatment process achieving pH adjustment, calcium and organic compound removal, and phosphate recovery using real impaired surface water. Three types of ion exchangers were integrated in train including a polystyrene strong base anion exchanger (psSBA), a shallow-shell weak acid cation exchanger (SSWAC), and a hybrid anion exchanger (HAIX). The novelty is that SSWAC, which decreased aqueous pH from neutral to ∼ 5 and removed > 70 % calcium, was regenerated by recovered waste CO2 (> 80 % regeneration efficiency) to avoid strong acid regenerants and achieve CO2 utilization and sequestration. The front-positioned psSBA selectively pre-removed hydrophobic ionizable organic compound (HIOC) such as diclofenac at > 80 % removal to reduce HIOC interference on the latter-positioned HAIX. HAIX doped with ferric oxide nanoparticles (FeOnp) enabled selective phosphate removal from complex real impaired water. Over 70 % removal of phosphate and calcium by HAIX and SSWAC reduced calcium phosphate scaling risk and facilitated phosphate recovery as hydroxyapatite from spent regenerants that enriched with calcium and phosphate. We envision this study to facilitate resource recovery in water-nutrient-carbon nexus via engineered multifunctional ion exchange processes.

P1615IDENTIFICATION OF URINARY PROTEOMIC PROFILE OF PATIENTS WITH CHRONIC ALLOGRAFT NEPHROPATHY

Abstract Background and Aims Chronic allograft nephropathy (CAN) is a major complication that occurs post-transplantation. At present, the diagnosis of chronic allograft nephropathy (CAN) is based on renal biopsy. Therefore, there is an ultimate need to identify more specific and sensitive noninvasive methods for the early diagnosis of CAN. Recently, proteomic-based modalities have been developed to discover biomarkers of CAN. Method Urine samples from 75 participants were collected. Participants were divided into 3 groups: Group I: 25 patients with chronic allograft nephropathy, group II: 25transplanted patients with stable renal functions, and group III: 25 healthy control subjects matched for age and sex. Each group was divided into training set and test set. Specimens were purified with magnetic beads-based weak cation exchange chromatography and analyzed in a MALDI-TOF MS. Results A Genetic Algorithm (GA) was used to set up the classification models. Five peaks represented the proteomic profile that differentiates between the CAN patients and the control group with sensitivity of 100%, specificity of 100%, recognition capability of 100 % and cross-validation91.7 % and five peaks differentiate between the transplant patients with normal renal functions and the control groups with sensitivity of96.8 %, specificity of 95.5 %, recognition capability of 98 % and cross-validation of 100 %. Conclusion We identified a pattern for CAN and transplant patients with normal renal functions by proteomic profiling using MALDI-TOF-MS and magnetic beads.

Comparative evaluation of peptidome and microbiota in different types of saliva samples

BackgroundClinical and research interest in salivary peptidome and microbiota is ever-growing owing to its great value for diagnosis, risk assessment and prediction of prognosis in oral and systemic diseases. Saliva can be stimulated for the purpose of rapid collection, but currently there are no studies systematically addressing the similarities and differences of salivary peptidome and microbiota in different types of samples. The purpose of this study was to investigate the variations of salivary peptidome and microbial profiles in response to different stimulating conditions.MethodsUnstimulated saliva and three types of stimulated saliva samples (olfaction, gustation, and mastication stimulated saliva) were collected from 10 systematically and orally healthy donors. The peptidome profiles were detected by weak cation exchange magnetic beads and analyzed through matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF MS), while their microbial profiles were analyzed by 16S rDNA V3-V4 hypervariable region amplicon sequencing utilizing the Illumina MiSeq PE300 platform. The distance matrixes of salivary peptidome and microbial profiles were generated and the intra-individual distances were extracted, then the variations brought by different sampling conditions and repeated collections were compared.ResultsBy comparisons of the overall salivary peptidome and microbial profiles, olfactory stimulation led to minimal variations comparing with that of unstimulated saliva, but appreciable variations were observed between saliva samples collected with gustatory/masticatory stimulation and unstimulated saliva. The three types of stimulated saliva exhibited significantly different peptidome and microbial profiles.ConclusionsStimulated saliva collected in response to olfactory stimulation is an appropriate alternative to unstimulated saliva, whereas gustatory/masticatory stimulation introduced appreciable variations. It is suggested that only one type of stimulating method should be used throughout one peptidome/microbiome research, which provides comprehensive insight into the optimization of sampling methods for salivaomic studies in the future.

Interaction of a Weak Acid Cation Exchange Resin (Dowex Mac 3H) with the Belousov‐Zhabotinsky Reaction and Estimation of Metal Ions

AbstractThe work pertains to the study on direct and indirect interaction of a macroporous weak acid cation exchange resin‐Dowex Mac 3H form with Belousov‐Zhabotinsky (BZ) reaction based on malonic acid‐cerium‐bromate‐sulfuric acid system. In the direct mode, the above reaction was perturbed by adding 10% (w/w) of Dowex Mac 3H at three different time intervals, i. e., before the start of induction period, during the induction period and after the commencement of oscillations. This mode of interaction was studied to investigate the effect of heterogeneity on the dynamics of BZ reaction. The indirect interaction of the resin was studied by interacting the resin individually with the optimized metal catalyst for a particular period of time after which the supernatant was used as initial reagent in the otherwise optimized BZ system. The interaction was monitored with respect to the change in oscillatory parameters before and after loading the resin with metal catalyst. The selectivity of the resin towards cerium and iron (ferroin) was studied through the said BZ reaction using potentiometry as the main technique. It was found that resin is more selective towards ferroin. The selectivity of the resin towards the various metal ions was followed by their estimation using UV‐Visible spectrophotometry. The effect of solvents on the ion exchange capacity (IEC) of the resin was also studied through the BZ reaction. Some solvents increased its IEC while others decreased it. The potentiometric results obtained were validated by spectroscopic findings and electrochemical studies.

Multifunctional ion exchange pretreatment driven by carbon dioxide for enhancing reverse osmosis recovery during impaired water reuse

Reverse osmosis (RO) has been increasingly applied for impaired water reuse in arid areas. However, enhancing RO recovery from scarce water resources is limited by energy demand for overcoming elevated brine osmotic pressure, and membrane scaling caused by concentrated poorly soluble salts. In this study, we present a hybrid ion exchange desalination process (HIX-Desal) as multifunctional RO pretreatment to enhance RO recovery by simultaneously desalinating feed water and removing multiple scale-forming ions (calcium, sulfate, and phosphate). The novelty of HIX-Desal is that carbon dioxide was the sole regenerant for a two-column train containing a hybrid anion exchanger (HAIX, with doped ferric oxide nanoparticles) and a shallow shell weak acid cation exchanger (SSWAC). We probed the desalination abilities of HIX-Desal at both lab and pilot scales using impaired water sources with varying total dissolved solids (TDS), where consistent desalination was achieved at 50–60% TDS reduction. Field tests demonstrated >80% removal of calcium, sulfate, and phosphate simultaneously. System configuration and SSWAC structure, i.e., intraparticle diffusion path length, were demonstrated to govern the HIX-Desal process during desalination and CO2 regeneration cycle. We envision this study to facilitate RO recovery enhancement and upcycling industrial carbon emission.

Preparation of suppressor column for capillary ion chromatography with conductivity detection

A capillary suppressor column was prepared by packed column and monolith columns. The packed column prepared using HyperSep SCX as packing material. The sulfonate group was introduced from benzenesulfunic acid that could be used as a suppressor material. The slurry of packing material was packed to capillary fused silica 0.53 mm I.D x 0.66 mm O.D with 30 mm of length. Monolith suppressor column was prepared from methacrylate based modified with Na2SO3 for strong cation exchanger and iminodiacetic acid for weak cation exchanger. A suppressor column was connected to a capillary chromatography system for separating 5 inorganic anions (Cl−, NO2 −, Br−, NO3 − and SO4 2-) using conductivity detection. The suppression system could reduce the background conductivity of the mobile phase sodium bicarbonate and sodium carbonate properly up to 67.72% using packed suppressor column with size 0.53 mm I.D x 0.66 mm O.D with 30 mm length. It column could be used about 1.5 hours before breakthrough.

A weak cation exchanger by encapsulating silica with maleic anhydride-modified polyvinyl alcohol.

A novel weak cation exchanger is described by encapsulating silica with a (or multiple) layer(s) of maleic anhydride-modified polyvinyl alcohol coating(s). The preparation method is facile and fast, which is simply performed by dipping silica particles into maleic anhydride-modified polyvinyl alcohol solution as-synthesized, then filtering and curing thermally, and finally generating a thin coating onto silica particles. Multiple layers of maleic anhydride-modified polyvinyl alcohol coatings can be generated by repeating above steps, offering an easy way to manipulate the capacity. The obtained weak cation exchanger demonstrated high separation efficiency and good selectivity toward common inorganic cations, for example, high plate count of 81000 per meter was obtained for NH4 + . Simultaneous separation of alkali and alkaline earth metals could be achieved within 14 min under isocratic conditions.

Fluoride removal from groundwater using Zirconium Impregnated Anion Exchange Resin

Drinking water containing excess fluoride is a major health concern across the globe. The present study reports the feasibility of zirconium impregnated hybrid anion exchange resin (HAIX-Zr) for treating fluoride contaminated groundwater. The HAIX-Zr resin was prepared by impregnating ZrO2 nanoparticles on polymeric anion exchanger resin. Fluoride uptake by HAIX-Zr was quite rapid, 60% removal was obtained within 30 min. Kinetics of fluoride uptake by HAIX-Zr resin followed the pseudo-second-order kinetic model and adsorption data fitted best to Freundlich adsorption isotherm model. Maximum fluoride uptake capacity was observed as 12.0 mg/g. The defluoridation capacity of the resin decreases with increase in solution pH. The co-existing anions like chloride, phosphate, bicarbonate, nitrate, and sulphate at 100 mg/L concentration significantly affected fluoride removal and bicarbonate showed the highest interference. Continuous flow packed bed experiments were performed with real groundwater. To maintain a lower pH, weak acid cation exchange resin (INDION-236) was used before HAIX-Zr. It was observed that reducing the pH of the sample water to 4–4.5, increased the number of treated bed volumes fifteen times. Regeneration of fluoride-containing resin was done by passing 3% NaOH and 3% NaCl solution through an exhausted resin bed. The results revealed that HAIX-Zr can effectively remove fluoride from groundwater.

Bullet points to evaluate the performance of the middle-down proteomics workflow for histone modification analysis.

Middle-down proteomics has emerged as the method of choice to study combinatorial histone post translational modifications (PTMs). In the common bottom-up workflow, histones are digested into relatively short peptides (4-20 aa), separated using reversed-phase chromatography and analyzed using typical proteomics methods in mass spectrometry. In middle-down, histones are cleaved into longer polypeptides (50-60 aa) mostly corresponding to their N-terminal tails, resolved using weak cation exchange-hydrophilic interaction liquid chromatography (WCX-HILIC) and analyzed with less conventional mass spectrometry, i.e. using Electron Transfer Dissociation (ETD) for analyte fragmentation. Middle-down is not nearly as utilized as bottom-up for PTM analysis, partially due to its limited reproducibility and robustness. This has also limited the establishment of rigorous benchmarks to discriminate good vs poor quality experiments. Here, we describe critical aspects of the middle-down workflow to assist the user in evaluating the presence of biased and misleading results. Specifically, we tested the use of porous graphitic carbon (PGC) during the desalting step, demonstrating that desalting using only C18 material leads to sample loss. We also tested different salts in the WCX-HILIC buffers for their effect on retention, selectivity, and reproducibility of analysis of variants of histone tail fragments, in particular replacing ammonium ion with ethylenediammonium ion in buffer A. These substitutions had marked effects on selectivity and retention. Our results provide a streamlined way to evaluate middle-down performance to identify and quantify combinatorial histone PTMs.

Determination of picomolar levels of methylmercury complexes with low molecular mass thiols by liquid chromatography tandem mass spectrometry and online preconcentration

Methylmercury (MeHg) is one of the most potent neurotoxins. It is produced in nature through the methylation of inorganic divalent mercury (HgII) by phylogenetically diverse anaerobic microbes. The mechanistic understanding of the processes that govern the extent of bacterial export of MeHg, its bioaccumulation, and bio-toxicity depends on accurate quantification of its species, especially its complexation with low molecular mass thiols; organometallic complexes that are difficult to detect and measure in natural conditions. Here, we report the development of a novel analytical method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine 13 MeHg complexes with important thiol compounds which have been observed in the environment and in biological systems. By using online preconcentration via solid phase extraction (SPE), the method offers picomolar (12–530 pM) detection limits, the lowest reported so far for the determination of MeHg compounds. Among three different SPE materials, a weak cation exchange phase showed the best efficiency at a low pH of 2.5. We further report the presence of MeHg-cysteine, MeHg-cysteamine, MeHg-penicillamine, MeHg-cysteinylglycine, and MeHg-glutamylcysteine as the predominant MeHg–thiol complexes in the extracellular milieu of an important HgII methylating bacterium, Geobacter sulfurreducens PCA, exposed to 100 nM of HgII.

Preparation and evaluation of a molybdenum disulfide quantum dots embedded C18 mixed-mode chromatographic stationary phase.

Molybdenum disulfide quantum dots (MoS2 QDs) were chosen as a functional two-dimensional material to improve the separation performance of a traditional C18 column. In this work, MoS2 QDs were synthesized by the combination of sonication and solvothermal treatment of bulk MoS2. The prepared MoS2 QDs were characterized by transmission electron microscope (TEM), Zeta potential measurement, UV-visible absorption and fluorescence spectroscopy. Then, a novel MoS2 QDs embedded C18 (Sil-MoS2-C18) stationary phase was prepared for performing mixed-mode liquid chromatography. The results of elemental analysis (EA), thermogravimetric analysis (TGA), Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Brunauer-Emmett-Teller (BET) measurements indicated the stationary phase was prepared successfully. Five types of compounds including alkylbenzenes, polycyclic aromatic hydrocarbons (PAHs), nucleosides and nucleobases, anilines and flavonoids were utilized to evaluate reversed phase, weak cation exchange and hydrophilic interaction of the new column. To a certain extent, the column could achieve separation for different properties of samples on one column, with less organic solvent and shorter time than conventional alkyl and amino columns. Furthermore, the mechanism for separation was studied by investigating effects of mobile phase composition and pH on retentions. In summary, the Sil-MoS2-C18 stationary phase was deemed able to serve the performance of various types of phases, which revealed the prepared mixed-mode column could be potentially applied for the analysis of complex samples. Graphical abstract.

Identification of urinary proteomic profile of patients with chronic allograft nephropathy

ABSTRACT Background and objectives Chronic allograft nephropathy (CAN) is a major complication that occurs post-transplantation. At present, the diagnosis of CAN is based on renal biopsy. Therefore, there is an ultimate need to identify more specific and sensitive noninvasive methods for the early diagnosis of CAN. Recently, proteomic-based modalities have been developed to discover biomarkers of CAN. Methods Urine samples from 75 participants were collected. Participants were divided into three groups: Group I: 25 patients with CAN, Group II: 25 transplanted patients with stable renal functions, and Group III: 25 healthy control subjects matched for age and sex. Each group was divided into training set and test set. Specimens were purified with magnetic beads-based weak cation exchange chromatography and analyzed using MALDI-TOF MS. Results A Genetic Algorithm (GA) was used to set up the classification models. Five peaks represented the proteomic profile that differentiates between the CAN patients and the control group with sensitivity of 100%, specificity of 100%, recognition capability of 100%, and cross-validation of 91.7% and five peaks differentiate between the transplant patients with normal renal functions and the control groups with sensitivity of 96.8%, specificity of 95.5%, recognition capability of 98%, and cross-validation of 100%. Interpretation and conclusions We identified a pattern for CAN and transplant patients with normal renal functions by proteomic profiling using MALDI-TOF-MS and magnetic beads.

Design, evaluation and optimization of taste masked clarithromycin powder.

Clarithromycin (CLA) is an extremely bitter macrolide antibiotic used to treat paediatric and adult infections. The bitter taste affects patient adherence and may compromise therapy. This research developed a taste masked CLA resinate using Indion® 234, a weak acidic cation exchange resin. The factors affecting formation of the CLA-resin complex were assessed. Design of experiments was used to optimize response while evaluating input variables such as temperature, CLA-resin ratio,stirring time and pH. CLA loading efficiency was determined spectrophotometrically and CLA release using USP Apparatus II. Differential Scanning Calorimetry (DSC), Scanning Electron Microscop (SEM), Fourier Transform Infrared (FT-IR) Spectroscopy and X-ray Diffraction (XRD) were used to confirm complex formation. A spectrophotometric method was used to assess taste evaluation. The optimum CLA-resin ratio, temperature, and stirring time were 1:4, 80 °C, 3 hours, respectively, at pH 8. Characterization techniques revealed that CLA was crystalline and the complex amorphous in nature. FT-IR spectra of resinate revealed the absence of resonance due to the tertiary amine functional group that is responsible for the bitter taste of CLA. CLA was stable in simulated salivary fluid and was released within 3 hours in gastric fluid. All CLAresin batches revealed complete taste masking. Taste analysis highlighted the improvement of taste masking properties of the resinate as the CLA to resin ratio, increased.

Studies on active aromatic constituents from rhizomes of Sophora tonkinensis

Aromatic constituents from rhizomes of Sophora tonkinensis were purified by extensive chromatographic techniques including column chromatography over macroporous resin,MCI,silica gel,weak acid cation exchange resin,Sephadex LH-20,ODS,and semi-preparative HPLC. Twelve aromatic compounds were isolated and identified from the water aqueous extract of the rhizomes of S.tonkinensis. Their structures were elucidated as 4-( 3-hydroxypropyl) phenol( 1),( ±)-4-( 2-hydroxypropyl) phenol( 2),benzamide( 3),( ±)-3-( p-methoxyphenyl)-1,2-propanediol( 4),4-methoxybenzamide( 5),3-hydroxy-1-( 4-hydroxy-3-methoxyphenyl) propan-1-one( 6),tyrosol( 7),( ±)-2,3-dihydroxypropyl benzoate( 8),vanillin alcohol( 9),7,3'-dihydroxy-8,4'-dimethoxyisoflavone( 10),7,4'-dihydroxy-3'-methoxyisoflavone( 11),and 7,3'-dihydroxy-5'-methoxyisoflavone( 12). Compounds 1-9 were firstly isolated from the Sophora genus. Compounds 4,5,10 and 11 can remarkably protect Hep G2 cell against APAP-induced damage at the concentration of 10 μmol·L-1. Compounds 1-12 exhibited no significant activities on the assays of inhibition of LPS-induced NO production in RAW cell lines and NF-κB inhibition.