Reversed-phase High-performance Chromatography Research Articles

Novel Stable Protease Inhibitor from Phoenix dactylifera(L.) Flowers with Antimicrobial and Antitumoral Activities.

A novel protease inhibitor isolated from date palm Phoenix dactylifera(L.) flowers (PIDF) was purified and characterized. A heat and acidic treatment step followed by ethanol precipitation and reverse-phase high-performance chromatography was applied to purify this natural protease inhibitor to homogeneity with a single band of about 19 kDa. The stability study depicted that PIDF was fully stable at 40 °C and retained 65% of its initial activity after heating at 50 °C for 24 h. Its thermal stability at 70 °C was markedly enhanced by adding calcium, bovine serum albumin, and sorbitol as well as by metal divalent cations, especially Mg2+ and Hg2+. This protease inhibitor showed high inhibitory activity against therapeutic proteases, including pepsin, trypsin, chymotrypsin, and collagenase, and acted as a potent inhibitor of some commercial microbial proteases from Aspergillus oryzae, Bacillus. sp, and Bacillus licheniformis. Moreover, a potent antibacterial spectrum against Gram (+) and Gram (-) bacterial strains and an efficient antifungal effect were observed. Its cytotoxicity toward human colorectal cancer cell LoVo and HCT-116 lines suggested that PIDF could serve as a new therapeutic target inhibiting human colorectal cancer.

In silico screening and characterization, inhibition mechanism on ACE, and stability of antihypertensive peptides with Zn-chelating capacity identified from millet bran albumin hydrolysates

To obtain Angiotensin-I-Converting Enzyme (ACE) inhibition peptides with Zn-chelating capacity, millet bran albumin hydrolysates (MBAH) were subjected to Sephadex G-15 gel and reverse phase-high liquid performance chromatography, and UPLC-ESI-MS/MS analysis. Five oligopeptides including Val-Gly-Ser-Asp-Gly-Leu (VGSDGL), Thr-Gly-His-Gly-Val-Ala (TGHGVA), Gly-Cys-His-His-Tyr (GCHHY), Leu-Val-Glu-Ala-Val-Pro-Arg-Gly (LVEAVPRG) and Val-Leu-Ala-Gln-Glu-Glu (VLAQEE) were identified in MBAH. Of these, only pentapeptide GCHHY showed both ACE-inhibitory activity (IC50: 134.78 μmol/L) and Zn-chelating capacity (14.16 mg/g). Molecular docking and inhibition kinetics showed that GCHHY was a competitive inhibitor of ACE, because it could bind with Lys511 of ACE which belongs to the central S2 pocket. Moreover, GCHHY can affect zinc tetrahedral coordination in ACE through binding with Glu411 and His383. The sulfhydryl, amino and carboxyl groups of GCHHY can bind with zinc ions. Under the gastrointestinal digestion, the ACE-inhibitory activity of GCHHY was relatively stable, and the zinc solubility of GCHHY-Zn complexes was more stable than zinc sulfate (P < 0.05). In addition, both GCHHY and GCHHY-Zn complexes lowered the diastolic blood pressure and systolic blood pressure of spontaneous hypertensive rats at dose of 50–200 mg/kg body weight. These results suggested the potential applications of millet albumin peptides as ingredients for antihypertension or zinc fortification.

A Stability Indicating Reverse Phase High Performance Liquid Chromatography Method for Related Substances of Sofosbuvir in Tablet Dosage Form

Sofosbuvir is an antiviral drug that is used to treat hepatitis C. A present investigation deals with simple, sensitive, rapid, precise and accurate reverse phase high-performance chromatography (RP-HPLC) method developed and validated for related substances of sofosbuvir in tablet dosage form. The chromatographic separation was achieved on a Kromasil 100 C18 (250 × 4.6 mm, 5 μ) column. A sofosbuvir and its impurities were extracted by composed mixture of Mobile Phase A: buffer solution: acetonitrile (97.5:2.5% v/v) and Mobile Phase B: acetonitrile, isopropyl alcohol, methanol and purified water (60:20:10:10 % v/v/v/v) using with flow rate was 1-mL/min, column temperature was 25°C, injection volume was 10 μL, Vial thermostat temperature was 10°C. The UV detection was carried out at 263 nm. The retention time of sofosbuvir, methyl ester and ethyl ester were 54.28, 36.31 and 43.77, respectively. The method shows linearity with correlation coefficient of sofosbuvir and its impurity was 0.999 over the 0.5–7.5 ppm range. The average recovery was found to be 90.2–113.9%. The LoD and LoQ for sofosbuvir and its impurities were found to be 0.1 and 0.5 μg/mL, respectively. The method was validated as per ICH guidelines. The developed method was precise, accurate, novel and detectable towards sofosbuvir and its impurity. This method is efficient in separating the sofosbuvir and its impurity. Hence, the proposed method can be utilized for the determination of related substances in routine analysis in quality control department of pharmaceutical Industry.

Selenocysteine Formation by Enterococcus faecium ABMC-05 Follows a Mechanism That Is Not Dependent on Genes selA and selD but on Gene cysK

Lactic acid bacteria (LAB) resist sodium selenite of concentrations greater than 100 mg/L in fermentation media. Selenium affects the growth rate, but once the microorganism absorbs selenium, this element is converted through a complex mechanism into selenocysteine and then into a selenoprotein structure. This study verified the presence of selenocysteine in Enterococcus faecium ABMC-05. The microorganism was cultivated in a medium enriched with a minimum inhibitory concentration of sodium selenite (184 mg/L). The concentration of selenium absorbed and the bioconversion into selenocysteine were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) and reverse-phase high-performance chromatography (RP-HPLC), respectively. The presence of the selD, selA, and cysK genes was determined by amplifying the 16S rDNA through polymerase chain reaction (PCR). The microorganism accumulated inorganic selenium, and part was transformed into selenocysteine. The growth curves were atypical for a lactic acid bacterium with a stationary phase greater than 70 h. Determining the genetic expression showed only the presence of the cysK gene and the absence of the selD and the selA genes. The results demonstrate that this microorganism produces selenocysteine through a mechanism independent of the SelA and SelD pathways in contrast to other LAB.

ACE-Inhibitory Peptides Identified from Quinoa Bran Glutelin-2 Hydrolysates: In Silico Screening and Characterization, Inhibition Mechanisms of ACE, Coordination with Zinc Ions, and Stability.

To obtain Angiotensin-I-Converting Enzyme (ACE) inhibition peptides with Zn-chelating capacity, quinoa bran glutelin-2 hydrolysates (QBGH) by Flavourzyme and Papain were subjected to Sephadex G-15 gel chromatography, reverse phase-high liquid performance chromatography and UPLC-ESI-MS/MS analysis. Four oligopeptides including GGGSGH, EAGAE, AGGGAGGG and AVPKPS were identified. Of these, only the hexapeptide AVPKPS had both ACE-inhibitory activity (IC50: 123.13μmol/L) and Zn-chelating ability (17.36mg/g). Molecular docking showed AVPKPS could bind with active residues Glu384 and Ala354 (both belong to the central S1 pocket of ACE including) through short hydrogen bond and hydrophobic interactions, respectively. Inhibition kinetics verified that AVPKPS was a competitive inhibitor of ACE. Moreover, AVPKPS can affect the zinc tetrahedral coordination in ACE through binding with residues His387 and His383. Fourier-transform infrared spectroscopy analysis demonstrated that the amino and carboxyl groups of AVPKPS were the main chelating sites for zinc ions. Under the gastrointestinal digestion, the ACE inhibition capacity of AVPKPS was relatively stable, and the zinc solubility of AVPKPS-zinc complexes was more stable than zinc sulfate (p < 0.05). These results suggest that quinoa peptides have potential applications as ingredients for antihypertension or zinc fortification.

Spiders’ digestive system as a source of trypsin inhibitors: functional activity of a member of atracotoxin structural family

Spiders are important predators of insects and their venoms play an essential role in prey capture. Spider venoms have several potential applications as pharmaceutical compounds and insecticides. However, transcriptomic and proteomic analyses of the digestive system (DS) of spiders show that DS is also a rich source of new peptidase inhibitor molecules. Biochemical, transcriptomic and proteomic data of crude DS extracts show the presence of molecules with peptidase inhibitor potential in the spider Nephilingis cruentata. Therefore, the aims of this work were to isolate and characterize molecules with trypsin inhibitory activity. The DS of fasting adult females was homogenized under acidic conditions and subjected to heat treatment. After that, samples were submitted to ion exchange batch and high-performance reverse-phase chromatography. The fractions with trypsin inhibitory activity were confirmed by mass spectrometry, identifying six molecules with inhibitory potential. The inhibitor NcTI (Nephilingis cruentata trypsin inhibitor) was kinetically characterized, showing a KD value of 30.25 nM ± 8.13. Analysis of the tertiary structure by molecular modeling using Alpha-Fold2 indicates that the inhibitor NcTI structurally belongs to the MIT1-like atracotoxin family. This is the first time that a serine peptidase inhibitory function is attributed to this structural family and the inhibitor reactive site residue is identified. Sequence analysis indicates that these molecules may be present in the DS of other spiders and could be associated to the inactivation of prey trypsin (serine peptidase) ingested by the spiders.

Analytical method for simultaneous estimation of voglibose and mitiglinide calcium hydrate by validated RP-HPLC method

A combination of Voglibose and Mitiglinide calcium hydrate is used in Type- 2 diabetes. The method was based on pre-column derivatization of Voglibose with 9-Fluorenylmethyloxycarbonyl chloride due to lack of chromophoric group it cannot directly estimated by UV detector in Reverse Phase High Performance Chromatography (RP-HPLC) method. The chromatographic separation was achieved using phosphate buffer (pH 4.0) and methanol (30:70) as mobile phase. Detection was carried out at 233 nm using UV detector. The retention time of Voglibose and Mitiglinide calcium hydrate were found to be 5.233 min and 3.580 min respectively. The RP-HPLC method for Voglibose and Mitiglinide calcium hydrate was found to be linear over the range of 0.5-1.50 µg/mL and 25-75 µg/mL respectively. Correlation coefficient for Voglibose and Mitiglinide calcium hydrate was found to be 0.998 and 0.999 respectively. Accuracy for Voglibose and Mitiglinide calcium hydrate was 99.79-100.94 % and 100.69-100.88 % respectively. A simple, specific, accurate and precise RP-HPLC method based on pre-column derivatization has been developed. There is a significant advantage in using 9- Fluorenylmethyloxycarbonyl chloride reagent, as the whole derivatization procedure is completed in a few minutes and easy to handle. All validation parameters lie within its acceptance criteria as per International Council for Harmonisation (ICH) guideline. The proposed RP-HPLC method can be highly suitable for analysis of Voglibose and Mitiglinide calcium hydrate without interference.

VALIDATION OF STABILITY INDICATING RP-HPLC METHOD FOR THE SIMULTANEOUS ESTIMATION OF JANUMET XR (SITAGLIPTIN/METFORMIN HCL EXTENDED-RELEASE FIXED DOSE COMBINATION (FDC) CONTENT IN BULK AND PHARMACEUTICAL DOSAGE FORM

A simple, accurate, precise and rapid stability indicating reverse phase High performance chromatography method was used for estimation of Sitagliptin/metformin HCl ER tablets in bulk and fixed-dose combination solid oral dosage form. The proposed analytical method has been validated for specificity, Linearity, Accuracy, Precision and Robustness. The chromatography was achieved in a Avantor, ACE C18 (Length 150 x Diameter 4.6mm Particle size 5µm) column with gradient flow. The optimal chromatographic condition consisted of mobile phase pH 3.5 at a flow rate of 1.2 mL/min, with a column temperature of 35°C, run time 17 minutes and detector wavelength of 210 nm (Sitagliptin&amp; Propyl gallate and Metformin HCl).

VALIDATION OF STABILITY INDICATING RP-HPLC METHOD FOR THE SIMULTANEOUS ESTIMATION OF TELMISARTAN AND HYDROCHLOROTHIAZIDE CONTENT IN BULK AND PHARMACEUTICAL DOSAGE FORM

A simple, accurate, precise and rapid stability indicating reverse phase High performance chromatography method was used for estimation of Telmisartan and Hydrochlorothiazide in bulk and fixed-dose combination solid oral dosage form. The proposed analytical method has been validated for specificity, Linearity, Accuracy, Precision and Robustness. The chromatography was achieved in a GL science, Inertsil C8 (Length 125x Diameter 4.0mm Particle size 5µm) column with gradient flow. The optimal chromatographic condition consisted of mobile phase pH 3.0 at a flow rate of 1.2mL/min, with a column temperature of 40°C, run time 14 minutes and detector wavelength of 270nm.

РАЗРАБОТКА И ВАЛИДАЦИЯ МЕТОДИКИ КОЛИЧЕСТВЕННОГО ОПРЕДЕЛЕНИЯ ПРИМЕСЕЙ В ТАБЛЕТКАХ «РАНОЛАЗИН-НАН»

The article presents the results of the research on the development of the procedure for determining related impurities by high-performance reversed-phase chromatography in the tablets “Ranolazin-NAN”. The conditions for samples preparation of ranolazine tablets, optimal conditions for the gradient mode of chromatography were selected using Zorbax Eclipse Plus C18 column: eluent A - 0,1% triethylamine buffer with pH 6,0 ± 0,1 (diluted with orthophosphoric acid) and acetonitrile in a ratio 70:30 v / v and eluent B - acetonitrile. The effect of pH medium (2,0, 6,0 and 9,0) on the efficiency of the column while studying the solutions of ranolazine and identified impurities was established. The suitability of the chromatographic system was proven and the specificity of the method for determining unidentified and identified impurities was proven. Linearity in the entire range of the procedure usage (from the quantitation limit to 125% (of the content of a single impurity)), correctness as well as precision at the level of reproductivity and intermediate precision, and the stability (robustness) of the method with small changes in the flow rate and column temperature were proven for the procedure of related impurities determination in Ranolazin-NAN tablets.

Validated RP-HPLC Method Development of Pazopanib in Bulk and its Pharmaceutical Dosage Form

Objectives: An accurate, sensitive, precise and rapid method for analysis and quantification of Pazopanib by Reverse Phase High Performance Chromatography (RP-HPLC) was developed and validated. Pazopanib in bulk and formulations were analyzed and quantification. Methods: Pazopanib in bulk and formulations were analyzed on Phenomenex enable C18 column (15x4.6mm, 5μm particle size) as stationary phase. Mobile phase was composed of acetonitrile and phosphate buffer (pH 5) in the ratio of 60:40%v/v at a flow rate of 1.2ml/min. elutes were analyzed using PDA detector at a detection wavelength of 290nm. The proposed method was validated by ICH guidelines, Validation of Analytical Procedures: Text and Methodology Q2 (R1). Results: In this study, the chromatographic peaks of Pazopanib showed good resolution with retention time of 2.190min. Pazopanib showed an excellent linearity with 0.998 of correlation coefficient. Other validation parameters including precision, specificity, accuracy and robustness demonstrated good reliability in the quantification of Pazopanib. Conclusion: Thus the newly developed and validated method can be conveniently used for the quantification of Pazopanib in bulk and formulation. The method can also be applied to multi-component drug analysis.

Quality analysis of raw and processed Schisandra chinensis fructus by simultaneous determination of eleven bioactive lignans using RP-HPLC method

A reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the simultaneous determination of eleven bioactive lignans, namely schisandrin, gomisin J, schisandrol B, angeloylgomisin H, gomisin G, schisantherin A, schisantherin B, deoxyschisandrin, γ-schisandrin, schisandrin B and schisandrin C in Schisandra chinensis with UV detection. An Elite ODS C18 column (250 mm × 4.6 mm, 5 μm) was used for chromatographic separation. The mobile phase consisted of acetonitrile and water under gradient elution. All the calibration curves of the eleven bioactive lignans showed excellent linearity (r ≥ 0.9995) within the ranges of 25.02-150.1 μg/mL for schisandrin, 5.20-31.20 μg/mL for gomisin J, 10.99-65.94 μg/mL for schisandrol B, 14.10-84.60 μg/mL for angeloylgomisin H, 2.55-15.30 μg/mL for gomisin G, 3.79-22.74 μg/mL for schisantherin A, 8.32-49.92 μg/mL for schisantherin B, 5.16-30.96 μg/mL for deoxyschisandrin, 9.10-54.60 μg/mL for γ-schisandrin, 20.70-124.2 μg/mL for schisandrin B and 4.56-27.36 μg/mL for schisandrin C. The average recoveries ranged from 97.74 to 102.71%. This analytical method was also validated with respect to precision, repeatability and accuracy; and it was proven to be sensitive and accurate to simultaneously determine the eleven lignans in S. chinensis. The developed method was further applied to quantify the contents of the eleven lignans in raw and processed S. chinensis. The results revealed that the contents of the eleven lignans increased after processing with vinegar and wine. The lignans profiles obtained by this newly established method provided valuable information for the differentiation of crude and processed S. chinensis and the different effects. These content ratio differences could provide a scientific basis for the selection of origins and clinical usage.

Hydrophobic interaction chromatography (HIC) method development and characterization of resolved drug-load variants in site-specifically conjugated pyrrolobenzodiazepine dimer-based antibody drug conjugates (PBD-ADCs)

Antibody drug conjugates (ADCs) are heterogeneous biopharmaceutical products that demand extensive characterization to ensure batch consistency, safety, and efficacy. Hydrophobic interaction chromatography (HIC) is the state-of-the-art analytical tool to monitor conjugation-related critical quality attributes (CQAs) e.g. drug-load distribution and Drug-to-Antibody Ratio (DAR). For the next generation site-specific PBD-ADCs (PBD: pyrrolobenzodiazepine dimer), denaturing RP-HPLC (reverse-phase high-performance chromatography) is the current method to determine average DAR. In this manuscript, we have utilized native HIC for the first time to understand conjugation related CQAs in PBD-ADCs. In terms of the method development, the type of stationary phase and salt, coupled with reduction of the reactive imine in the PBD drug-linker to an amine form in the sample preparation, have played a key role in achieving the best HIC resolution for the drug-load variants. The established HIC conditions resolved DAR 0, DAR 1, and two DAR 2 peaks for PBD-ADCs. Extended characterization of the DAR 2 peaks confirmed that they have retained characteristically distinct antibody Fc N-glycan distributions (Fc = Fragment crystallization region). Therefore, the results support that the HIC conditions established for PBD-ADCs is valuable in not only determining DAR values but also other important attributes including native drug-load distribution and unique DAR 2 conformations existed as a result of the N-glycan heterogeneity.

Advanced analytical tools for bovine lactoferrin identification and quantification in raw skim milk to finished lactoferrin powders

As the use of bovine lactoferrin (bLF) has increased, greater regulatory and commercial interest is being placed on bLF identification and quantitation and quality. Several methods can be used to quantitate bLF, but a robust accurate quantification method applicable as a standardised tool for feed milk, process monitoring, and evaluation of end products has been less of a concern. bLF concentrations increase through the bovine lactation cycle, so accurate and timely information is required that can increase both processing plant performance and product quality and output. In this article we evaluate analytical cation exchange, reverse phase high-performance chromatography and size exclusion chromatography methods for the analysis of bLF identification and quantification from whole milk, process intermediates, ingredients, milk and infant formula products. However, the methods described in this article to identify and quantify the bLF may not be directly assimilated to the biological activities of the bLF.

A VALIDATED STABILITY INDICATING RP-HPLC METHOD FOR ESTIMATION OF TOLFENAMIC ACID IN PRESENCE OF ITS PHARMACOPOEIAL IMPURITIES

Objective: The proposed research work was conducted to develop a single reverse-phase high-performance chromatography (RP-HPLC) method capable of separating two Pharmacopoeial related impurities as well as degradation product of Tolfenamic acid (TA). The drug was subjected to various stress conditions recommended under ICH Q1A (R2) guidelines.&#x0D; Methods: The desired separation of two Pharmacopoeial impurities and one degradant generated under oxidative stress was carried out using Sunfire ODS C-18 (250 x 4.6 mm, 5 µm) column maintained at 40 °C. Isocratic elution was carried out using acetonitrile and ammonium dihydrogen orthophosphate buffer (10 mmol, pH 2.5) in the ratio of 80:20 v/v. The detection was carried out at 205 nm using flow rate of 1 ml/min. The developed method was validated as per ICH Q2 (R1) guidelines for specificity, linearity, accuracy, precision, Limit of detection (LOD), Limit of Quantification (LOQ) and robustness.&#x0D; Results: Linearity response of TA was found at a concentration range of 10-100µg/ml, with a correlation coefficient of 0.9987. The Pharmacopoeial impurity A and impurity B showed linearity results at concentration of 0.1-1µg/ml, with correlation coefficient of 0.9984 for Impurity A and 0.9989 for Impurity B. The % recovery during accuracy studies for TA and the two impurities were within the acceptance range of 95-105%. LOD and LOQ for TA were found to be 4.561µg/ml and 133.771µg/ml respectively. For impurity A, LOD and LOQ were found to be 0.035 µg/ml and 0.106 µg/ml and for Impurity B, LOD and LOQ were 0.042 µg/ml and 0.128 µg/ml. With slight variation of organic phase in mobile phase and flow rate the method exhibited good robustness. Under forced degradation studies the drug was found stable under hydrolytic, photolytic and thermal stress conditions, but was found susceptible for degradation under oxidative stress with appearance of a degradant peak. From on the RRT values of Pharmacopoeial impurities and the formed degradant it was inferred that the developed method is selective for the drug in the presence of impurities or degradants.&#x0D; Conclusion: The developed stability-indicating method is found to be simple, rapid, accurate, precise and robust as compared to other proposed methods while determining TA in presence of its Pharmacopoeial impurities and degradation products. Hence the developed method can be used for analysis of stability samples of TA in presence of its related impurities.

WORKING OUT QUALITY STANDARDS OF MODEL COMPOSITION SAMPLES OF GRANULATED DOSAGE FORM WITH GLUTATHIONE RESTORED

Biologically active sulfur-containing compounds (BASC) exhibit pronounced antioxidant properties. Glutathione reduced (GSH) occupies a particular position among these compounds. It represents a key link in the 3 antioxidant systems of the body from the existing four. Based on the foregoing, a GSH-based dosage form with antioxidant properties was proposed. The aim of this study is to work out a model granulated dosage form based on GSH and methods of its analysis by means of pre-column derivatization with ortho-phthalic aldehyde.Materials and methods.GSH and granulated dosage form based on GSH obtained by wet granulation were used as the object of the study. Quantitative evaluation of GSH content in the obtained granules was carried out using pre-column derivatization by the method of reversed-phase high-performance chromatography (RP HPLC). Ortho-phthalic aldehyde was used as a derivatizing agent. A diode-array detector was used to detect the resulting derivative. Ortho-phthalic aldehyde was used as a derivatizing agent. A diode-matrix detector was used to find out the resulting derivative.Results.In the course of the work, a model dosage form was created – granules based on GSH. By reference to the recommendations on the dosage of the drug, the concentration of the active substance was selected. Lactose was chosen as an auxiliary component. Physical and technological characteristics of a model sample of granules with GSH and lactose as a filler were studied. A method of quantitative determination of GSH in granules using pre-column derivatization with ortho-phthalic aldehyde was developed and validated by HPLC. The method of quantitative determination of GSH in granules with the use of pre-column derivatization by ortho-phthalic aldehyde by HPLC was developed and validated.Conclusion.The developed granulated dosage form meets the requirements given in the pharmacopoeial item “Granules” according to the analyzed indicators. Using the validation evaluation it was established, that the developed methods for the quantitative determination of GSH in granules is correct, precise and specific.

Optimization and Validation of Reversed Phase High Performance Chromatography Method for Rapid Estimation of Theaflavin

The manuscript deals with the optimization of simple, rapid, sensitive and economic HPLC method for estimation of Theaflavin in Camellia sinensis extract and Theaflavin loaded nanoformulation. The preliminary screening was performed employing fractional factorial (25-1) design with mobile phase pH, flow rate, column temperature, injection volume, and acetonitrile concentration as independent variables while tailing factor as the dependent variable. The separation was achieved using the isocratic system as mobile phase, flow rate of 1 ml/min, and ultraviolet detection at 275 nm. Upon further evaluation, the method revealed a high degree of linearity, accuracy, precision, sensitivity and robustness, while, forced degradation studies indicated stability of Theaflavin at pH 3-6 in an air tight, light-protected container. The method when applied towards estimation of Theaflavin in C. sinensis extract and Theaflavin loaded nanoformulation, indicated no significant change in retention time. Thus, a HPLC method for rapid estimation of Theaflavin with an understanding of influencing variables for enhancing the method performance was developed.

DEVELOPMENT OF METHODS OF PRE-COLUMNAR DERIVATIZATION OF GLUTATHIONES RECOVERED BY 4-METHOXY-2-NITROPHENYLISOTHIOTOCIONATE FOR DETERMINATION BY METHOD OF HIGH-EFFECTIVE LIQUID CHROMATOGRAPHY

Nowadays the pharmacological role of glutathione in the therapy of carcinogenesis, neurodegenerative and ocular diseases, heart diseases, the immune system and aging of the organism is being actively investigated. Therefore, for the development of pharmaceutical medical forms on its basis, it is necessary to create an optimal analytical base. The aim of this study is to develop a methodology for the analysis of glutathione recovered by pre-columnar derivatization of 4-methoxy-2-nitrophenyl isothiocyanate. Materials and methods. Since glutathione does not have the necessary spectral characteristics for its direct analysis, a methodology for the determination of glutathione with the use of pre-columnar derivatization of 4-methoxy-2-nitrophenyl-isothiocyanate by reversed-phase high-performance chromatography (RP HPLC) has been developed on that basis. Detection of the resulting derivative has been carried out by absorption in UV light using a diode array detector. Results and discussion. In the course of the experiment described, chromatograms of a glulathione derivative with 4-methoxy-2-nitrophenyl isothiocyanate were obtained. This technique was also evaluated for the possibility of quantitative determination of glutathione. The sensitivity of the methods was 0.01% or 3.1*10-1 mol. The linear relationship between the analytical signal (peak area) and concentration was observed within the range of 0.01–0.08% and the correlation coefficient of 0.995. Conclusion. In the course of the studies, a methodology for the determination of glutathione has been developed with the use of pre-columnarderivatization of 4-methoxy-2-nitrophenyl-isothiocyanate by RP HPLC. In this case, the derivative is formed with the retention time of 22.3 minutes and the absorption maximum of 398 nm. This method also allows estimating the quantitative content of the object under study.

Complex of a new racemic thiourea substrate: Spectrophotometric study and separation of atropisomers

The activity of a chiral molecule can vary from one atropisomer to the other. In this study, the separation of racemic-N-(2-methylphenyl), N’-(2-chlorophenyl) thiourea (H 2 L 2 ), a hydrophobic heavy metal trap, has been studied using reversed-phase high-performance liquid chromatography (RP-HPLC) with hydroxypropyl-beta-cyclodextrin (HP-β-CD) as a complexing additive to the racemic mixture and hexane-isopropanol as a mobile phase. The stoichiometry and the overall association constant of the complex have been determined using the continuous variation (Job's plot) method and the Scott's method respectively.

Effect of tamoxifen on the sphingolipid biosynthetic pathway in the different intraerythrocytic stages of the apicomplexa Plasmodium falciparum

Parasites of the genus Plasmodium responsible for Malaria are obligate intracellular pathogens residing in mammalian red blood cells, hepatocytes, or mosquito midgut epithelial cells. Regarding that detailed knowledge on the sphingolipid biosynthetic pathway of the apicomplexan protozoan parasites is scarce, different stages of Plasmodium falciparum were treated with tamoxifen in order to evaluate the effects of this drug on the glycosphingolipid biosynthesis. Thin layer chromatography, High performance reverse phase chromatography and UV-MALDI-TOF mass spectrometry were the tools used for the analysis. In the ring forms, the increase of NBD-phosphatidyl inositol biosynthesis was notorious but differences at NBD-GlcCer levels were undetectable. In trophozoite forms, an abrupt decrease of NBD-acylated GlcDHCer and NBD-GlcDHCer in addition to an increase of NBD-PC biosynthesis was observed. On the contrary, in schizonts, tamoxifen seems not to be producing substantial changes in lipid biosynthesis. Our findings indicate that in this parasite, tamoxifen is exerting an inhibitory action on Glucosylceramidesynthase and sphingomyelin synthase levels. Moreover, regarding that Plasmodium does not biosynthesize inositolphosphoceramides, the accumulation of phosphatidylinositol should indicate an inhibitory action on glycosylinositol phospholipid synthesis.