Reversed-phase High-performance Liquid Chromatography Research Articles

Features and Advantages of the Recurrent Approximation of Retention Times in Reversed-Phase High-Performance Liquid Chromatography

Background: Recurrent approximation of retention parameters in reversed-phase HPLC is effective for revealing anomalies that are otherwise difficult to detect, namely, the reversible hydration of analytes. This was demonstrated previously for restricted sets of analytes with acetonitrile–water eluents. Expanding the number of analytes and eluents seems to be a topical problem. Two kinds of derivatives of aromatic carbonyl compounds were characterized: unsubstituted hydrazones and oximes. Methods: If analyte demonstrates no anomalies in dependences of retention times vs. concentration of organic modifier, the recurrent approximations of these dependences are linear. To explain the features of recurrent approximations, the numerical experiments were proposed and considered. The artificial shifting of one, two, or more points allows for the modeling the different kinds of deviations of approximations from linearity. Results: It was shown that hydrazones are the class of analytes having no anomalies of retention parameters. On the contrary, several anomalies were detected for oximes. Downward deviations of points in the plots of recurrent approximations of retention times are the signs of reversible hydration. This effect for methanol–water eluents was detected for the first time. Some of oximes underwent hydrolysis. Conclusions: Recurrent approximation of retention times allows detecting chemical transformations of analytes during RP HPLC analysis.

The Oxidative Status and Na+/K+-ATPase Activity in Obsessive-Compulsive Disorder: A Case Control Study.

Oxidative stress is involved in pathogenesis of some psychiatric disorders. To examine the role of oxidative stress in the etiopathogenesis of obsessive-compulsive disorder (OCD), we aimed to determine oxidative stress indices, including malondialdehyde (MDA) levels in serum and red blood cells (RBC) membrane, total antioxidant capacity (TAC), serum glutathione (GSH) levels, serum antioxidant vitamins (A and E), and Na+/K+-ATPase activity, in patients with the mentioned disorder vs. healthy controls. 39 OCD patients diagnosed based on Diagnostic and Statistical Manual of Mental Disorders (DSM-V) and 39 volunteer healthy subjects were included in this study. MDA levels in serum and RBC membrane were measured using fluorometric method. Serum TAC level, serum GSH level, and Na+/K+-ATPase activity were also measured using spectrophotometric methods. Serum levels of vitamins were calculated by reversed-phase high-performance liquid chromatography (RP-HPLC). There was a significantly higher MDA level in serum (p < 0.0001) and RBC membrane (p = 0.002) of OCD patients compared with those in controls. A significant reduction in vitamin A (p = 0.001) and vitamin E (p = 0.024) levels was found in OCD patients vs. controls. There was significantly lower activity of erythrocyte membrane Na+/K+-ATPase in RBC membrane of OCD patients vs. controls (p < 0.0001). Our findings indicate significantly higher levels MDA in both serum and RBC membrane, lower levels of serum vitamins A and E, and lower activity of membrane Na+/K+-ATPase in OCD patients compared to controls. These suggest an imbalance between oxidant and antioxidant factors in OCD patients that might play a fundamental role in the etiopathogenesis of OCD.

Isolation and antioxidant activity of peptides from Chinese hairy tofu.

Hairy tofu is a famous Chinese snack that is made from soybeans and rich in various nutrients. In order to further explore the antioxidant peptides of hairy tofu hydrolysates, seven proteases were used to hydrolyze hairy tofu. The results of in vitro radical scavenging activity showed that hairy tofu hydrolysates obtained by pancreatin exhibited the highest antioxidant activity. After Sephadex G-25 gel filtration and reversed-phase high-performance liquid chromatography (RP-HPLC), 97 peptides were identified in the most antioxidant fraction using liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Among them, nine peptides were synthesized and their antioxidant activities were assessed using a H2O2-induced oxidative 293T cell model. Finally, four peptides (QCESHK, LAWNEGR, NLQGENEWDQK, and FTEMWR) at concentrations of < 50 μg/ml significantly decreased the malondialdehyde content compared with the model group, displaying in vivo antioxidant activity and low cytotoxicity. Overall, this research provided the choice of using hairy tofu peptides as antioxidant products in the pharmaceutical and food industries.

A novel Six Sigma approach and eco-friendly RP-HPLC technique for determination of pimavanserin and its degraded products: Application of Box–Behnken design

Abstract A green analytical chemistry study attempts to generate environmentally friendly alternatives to dangerous compounds while reducing waste output. The study thoroughly analyzed eight green tools to determine their greenness. Given its importance in treating hallucinations and delusions produced by Parkinson’s disease psychosis, it is critical to have a reliable and precise method for identifying pimavanserin (PVS) in both pure form and pharmaceutical formulations. The current study used a straightforward approach to forced degradation experiments to establish a novel reversed-phase high-performance liquid chromatography method for evaluating stability. The method was executed on the Agilent Zorbax Eclipse Plus C18 column (100 × 4.6 mm, 3.5 μm particle size) with ultraviolet detection at 226 nm. The Box–Behnken design is the ultimate solution for identifying optimal chromatographic conditions in a timely and efficient manner, with minimal trials required. The study investigated the impact of three factors: acetonitrile ratio, column oven temperature, and flow rate on various responses, namely, retention time, tailing factor, and theoretical plates. Desirability and overlay plots were utilized to forecast the best mobile phase containing a buffer solution: acetonitrile: tetrahydrofuran in a ratio of (65: 20: 15, v/v/v), which proved highly effective in the experiments. Linearity was conducted for PVS in the 3–50 µg·mL−1 range with an R 2 coefficient of determination of 0.9997. PVS had detection and quantification limits of 1.1 and 3.5 µg·mL−1, respectively, indicating a highly significant correlation between the variables studied. PVS’s recovery percentage was determined to be 101.30%. We also used the Six Sigma lean technique to ensure precision and productivity. PVS was tested for acid, base, oxidative hydrolysis, photodegradation, and heat, as per International Council for Harmonisation guidelines. The highest degradation was obtained from oxidative hydrolysis and thermal degradation.

Simultaneous Identification and Quantification of Phenylalanine, Glycine and Lysine amino acids and conjugated heterocyclic amines in Maillard chemical model system using RP-HPLC-DAD

In this study, we developed a simple reversed-phase high-performance liquid chromatography (RP-HPLC) methodology for simultaneous identification and quantification of three types of mix: (1) phenylalanine and PHIP; (2) glycine and MeIQx; (3) lysine and 4,8 DiMeIQx in Maillard chemical model systems. In addition, we investigated the effects of different conditions on decreasing amino acids and heterocyclic amines (HCA) formation in chemical model systems. The results show that the developed methods used to separate the proposed mixes gave a relative standard deviation (RSD)% of less than 2% of peak area and retention time, thus proving the robustness and high reproducibility of the proposed method. The relationship between concentration and peak areas is linear with high statistical significance (p&lt;0.001). The residual and slope of linear regression give a limit of detection LoD) and (LoQ) of phenylalanine and PHIP were (2.92- 0.029 ppm),(9.73- 0.098 ppm),respectively, which indicate the high sensitivity of the developed method. Moreover, the findings illustrate that a water ratio of 20% leads to a decrease in phenylalanine versus the largest amount of PHIP, and phenylalanine is the most active amino acid with a decreasing percentage up to 99%.

Simultaneous Analysis of Anti-Hypertensive Drugs by RP-HPLC: An Overview

High performance liquid chromatography (HPLC) is an important qualitative and quantitative technique, generally used for the estimation of pharmaceutical and biological samples. In now a day pharmaceutical market, many newer antihypertensive combination drugs are available to control hypertension as well as to keep society healthy and stress free. All presently available old drugs have frequent dosing produces various side effects. So, there is need to analyse such antihypertensive drugs. The aim of this review is to analysed such commonly used antihypertensive combination drugs by using reverse phase high performance liquid chromatography (RP-HPLC). Reversed-phase high-performance liquid chromatography (RP-HPLC) involves the separation of molecules on the basis of hydrophobicity. The separation depends on the hydrophobic binding of the solute molecule from the mobile phase to the immobilized hydrophobic ligands attached to the stationary phase. The drugs like Amlodipine besylate and Valsartan, Irbesartan and Hydrochlorothiazide, Atenolol and Chlorthalidone, Hydrochlorothiazide and Candesartan, Ramipril and Amlodipine, Hydrochlorothiazide and Enalapril, Quinapril and Hydrochlorothiazide etc. About fifteen combination drugs are analysed by using RP-HPLC. This review assists in appropriate selection of column, mobile phase, pH, flow rate, detector and form of such combination drugs.

Purification and Identification of Peptides from Hydrilla verticillata (Linn. f.) Royle with Cytoprotective and Antioxidative Effect against H2O2-Treated HepG2 Cells.

Antioxidant peptides were purified from Hydrilla verticillata (Linn. f.) Royle (HVR) protein hydrolysate by ultrafiltration, gel filtration chromatography, and semipreparative reversed-phase HPLC and identified by UPLC-ESI-MS/MS. Therein, TCLGPK and TCLGER were selected to be synthesized, and they displayed desirable radical-scavenging activity to ABTS (99.20 ± 0.56-99.20 ± 0.43%), DPPH (97.32 ± 0.59-97.56 ± 0.97%), hydroxyl radical (54.32 ± 1.27-70.42 ± 2.01%), and superoxide anion (42.93 ± 1.46-52.62 ± 1.11%) at a concentration of 0.96 μmol/mL. They possessed a cytoprotective effect against H2O2-induced oxidative stress in HepG2 cells in a dose-dependent manner. 1.6 μmol/mL of the two peptides could perfectly protect HepG2 cells from H2O2-induced injury. The TCLGPK exhibited higher antioxidant activity and cytoprotective effect than TCLGER. Western blot and molecular docking results indicated that the two peptides achieved antioxidant ability and cytoprotective effect by combining with Kelch-like ECH-associated protein 1 (Keap1) to activate the Keap1-nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response elements signaling pathway, leading to the activity and expression of the related antioxidases in the pathway significantly up-regulating and the intracellular reactive oxygen species level, lipid peroxidation, and cell apoptosis rate significantly down-regulating.

Quantification of Riboflavin and Thiamine in GI (Geographical Indication) Branded Yogurts Collected from Bogura, Bangladesh Using HPLC Equipped with a Fluorescence Detector

Thiamine (vitamin B1) and riboflavin (vitamin B2) are both essential vitamins for human health. Thiamine (vitamin B1) is essential for energy metabolism, nervous system function, carbohydrate metabolism, cardiovascular health, digestion, muscle function, etc. On the other hand, Riboflavin (vitamin B2), which acts as an antioxidant, is essential for energy production, healthy skin, hair and nails, eye health, red blood cell production, nervous system function, etc. Due to its specialty, Bogura's famous yogurt was recognized as a Geographical Indication (GI) on June 26, 2023 by the Directorate of Patents, Designs, and Trademarks (DPDT) under the Ministry of Industry, the Government of the People’s Republic of Bangladesh (Prothom Alo, 2023). The purpose of the study was the quantitative determination of two water-soluble vitamins, thiamine and riboflavin, in the GI branded yogurt and whey (Ghol), collected from Bogura, Bangladesh to ensure health benefits. The methods employed for the quantitative analysis of these vitamins were reversed-phase high performance liquid chromatography (RP-HPLC) equipped with a fluorescence detector. The extraction process involved acid hydrolysis followed by enzymatic hydrolysis with takadiastase enzyme. Chromatographic separation was achieved with a Shimadzu Prominence HPLC system using isocratic elution mode on a C18 column (4.6 mm × 250 mm, 5 μm). The correlation coefficients for thiamine and riboflavin were 0.9975 and 0.9974, respectively. The recovery rates for thiamine and riboflavin were found as 97.70% and 105.40%, respectively. Twenty-two samples were analyzed. Thiamine and riboflavin were found in the range of 0.0647 to 0.1396 mg/100 g and 0.0227 to 0.3749 mg/100 g, respectively. It can be concluded that these yogurts were rich in thiamine and riboflavin. Therefore, these yogurts are beneficial for health. Bangladesh Pharmaceutical Journal 27(1): 59-66, 2024 (January)

A comparative novel green reversed-phase high-performance liquid chromatography method for simultaneous determination of ivabradine and carvedilol in tablets and human plasma using UV and fluorescence detectors

A rapid, green, and sensitive dual detection technique method was applied using both UV and fluorimetric detection to determine ivabradine and carvedilol in their pure form, combined tablet formulation, and in the spiked human plasma. The method was achieved by using HyperClone™ MOS C8 column (150 × 4.6 mm, with particle size 5 μm), and a mixture composed of (70:10:20%v/v) ethanol: methanol: 0.02 M potassium phosphate buffer adjusted to pH = 3 b y using o-phosphoric acid. The dual detection technique was performed at 210 nm in the case of UV detection, and at 337 nm after excitation at 282 nm in the case of fluorimetric detection with a flow rate of 1 mL/min. The retention time in the proposed method was found to be 2.13 and 4.72 min for carvedilol and ivabradine respectively (UV detection) and 2.16 and 4.5 min for carvedilol and ivabradine respectively (fluorescence detection). It was found to be a rectilinear method (r > 0.999), precise (RSD <2 %), and accurate (recoveries 99.92 and 100.52). The method was simple, specific, sensitive, and robust. Calibration graphs were found to be rectilinear from 0.25 to 11.25 μg/mL and 0.50–16 μg/mL for carvedilol and ivabradine for UV detection, while from 30 to 210 ng/mL and 48–400 ng/mL for carvedilol and ivabradine for fluorimetric detection. A correlation coefficient (r) was 0.9999 for the two drugs in UV and fluorimetric detection approaches. Fixed–dose combination tablets containing both medications could be examined routinely by the validated method without interference from excipients. Moreover, the fluorimetric detection HPLC technique can be applied to determine the studied drugs in the human plasma with high accuracy and precision. Greenness of the method was assessed by using Eco-scale and AGREE metrics, and the method was found to be green.

Process optimization and identification of antioxidant peptides from enzymatic hydrolysate of bovine bone extract, a potential source in cultured meat

Bone protein is a significant secondary product of the meat industry, comprising a substantial quantity of protein. These proteins could be broken down through enzymatic hydrolysis to generate antioxidant peptides. This study aimed to produce antioxidant peptides from bovine bone extract by enzymatic hydrolysis utilizing Flavourzyme and Protamex by optimizing enzyme amounts and time using the Box–Behnken design. The final optimized conditions obtained through the model were as follows: The amount of Flavourzyme was 1,100 U, the amount of Protamex was 2,814 U, and the time was 3.77 (h). Bovine bone extract hydrolysate (BBEH) was purified stepwise using ultrafiltration membranes with molecular cutoffs of 5, 3, and 1 kDa. To assess the antioxidant capacity of the fractions, several methods were used, including radical scavenging activity “1,1-diphenyl-2-picrylhydrazyl (DPPH),” “2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS),” metal chelating activity (MCA), reducing power (RP), and thiobarbituric acid assay (TBA). The results indicated that the ultrafiltration fraction with a molecular weight of less than 1 kDa showed significant antioxidant activity, with 48, 42, and 50% inhibition rates for DPPH, ABTS, and metal chelating, respectively. Using size exclusion chromatography, the fraction with a molecular weight less than 1 kDa was further separated into five sub-fractions: Frac-I, Frac-II, Frac-III, Frac-IV, and Frac-V. Sub-Frac-III, which exhibits significant DPPH radical scavenging activity (55%) and a reducing power of 0.8 at 700 nm, was separated into six sub-sub-fractions using reversed-phase HPLC (RP-HPLC) based on molecular weight and hydrophobicity. The sub-sub-fraction with the highest value for DPPH radical scavenging activity was sub-Fra-III-6, which exhibited approximately 69.45% activity. The sub-Fra-III-6 was analyzed using LC–MS/MS, which identified two specific peptides: Ala-Pro-Phe with a mass of 333.12 Da and Asp-His-Val with a mass of 369.14 Da. These two peptides are likely the primary peptides that might have a crucial role in antioxidant capacity. It can be concluded that BBEH is a valuable source of natural antioxidants and has the potential to serve as a viable resource in the cultured meat industry.

Simple Determination of Bosentan in Plasma Samples by Reversed-Phase High-Performance Liquid Chromatography.

In order to measure the plasma levels of Losartan and Bosentan, a sensitive Reverse Phase-High Performance Liquid Chromatography (RP-HPLC) technique was developed. To compare bioavailability, the Area Under the Curve (AUC), peak plasma concentration (Cmax), and time to Cmax (Tmax) were employed. The standard curve (150-2400 ng/ml) was linear (R2=0.999), relative errors were between 2.4 to 10.05% and the coefficient of variation (CV%) ranged from 1.52 to 10.88. A single dosage (test and reference) was used for the in vivo investigation, which involved 16 healthy individuals. The AUC0-48, AUC0-, Cmax, and Tmax of the test and reference had no statistically significant differences. The Cmax and 95% confidence intervals of the ratio of Cmax of the two formulations were 0.93-0.96 and 97.6-135%, respectively. Therefore, it was established that generic Bosentan was equivalent to Bosentan from Actelion and that both medications could be regarded as equally effective in clinical settings. The blood level of Bosentan could be measured using this straightforward procedure in all hospital laboratories.

Optimisation of denaturing ion pair reversed phase HPLC for the purification of ssDNA in SELEX

Aptamers have shown great promise as oligonucleotide-based affinity ligands for various medicinal and industrial applications. A critical step in the production of DNA aptamers via selective enhancement of ligands by exponential enrichment (SELEX) is the generation of ssDNA from dsDNA. There are a number of caveats associated with current methods for ssDNA generation, which can lower success rates of SELEX experiments. They often result in low yields thereby decreasing diversity or fail to eliminate parasitic PCR by-products leading to accumulation of by-products from round to round. Both contribute to the failure of SELEX protocols and therefore potentially limit the impact of aptamers compared to their peptide-based antibody counterparts.We have developed a novel method using ion pair reversed phase HPLC (IP RP HPLC) employed under denaturing conditions for the ssDNA re-generation stage of SELEX following PCR. We have utilised a range of 5′ chemical modifications on PCR primers to amplify PCR fragments prior to separation and purification of the DNA strands using denaturing IP RP HPLC. We have optimised mobile phases to enable complete denaturation of the dsDNA at moderate temperatures that circumvents the requirement of high temperatures and results in separation of the ssDNA based on differences in their hydrophobicity. Validation of the ssDNA isolation and purity assessment was performed by interfacing the IP RP HPLC with mass spectrometry and fluorescence-based detection.The results show that using a 5′ Texas Red modification on the reverse primer in the PCR stage enabled purification of the ssDNA from its complimentary strand via IP RP HPLC under denaturing conditions. Additionally, we have confirmed the purity of the ssDNA generated as well as the complete denaturation of the PCR product via the use of mass-spectrometry and fluorescence analysis therefore proving the selective elimination of PCR by-products and the unwanted complementary strand. Following lyophilisation, ssDNA yields of up to 80% were obtained. In comparison the streptavidin biotin affinity chromatography also generates pure ssDNA with a yield of 55%. The application of this method to rapidly generate and purify ssDNA of the correct size, offers the opportunity to improve the development of new aptamers via SELEX.

Proteomic Analysis and Immunoprofiling of Persian Horned Viper Venom, Pseudocerastes Persicus, from Central Part of Iran.

Numerous species of venomous snakes of medical importance exist in Iran. Pseudocerastes persicus (P. persicus), one of the medically important snakes, also called the Persian horned viper, has a geographical spread that extends to the east, southwest, and central areas of Iran and is endemic across the wider region. As a result, this species is responsible for many snakebite occurrences. Venom from P. persicus found in the central province of Semnan contains phospholipase A2 and L-amino acid oxidase activities, and high toxic potency. The venom was fractionated by reverse-phase high-performance liquid chromatography (HPLC) and analyzed by Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), Western blotting and two-dimensional electrophoresis. Using liquid chromatography with tandem mass spectrometry (LC-MS/MS), a range of components were identified, consistent with the biochemical and toxicological properties of the venom. Proteins identified from 2D electrophoresis and shotgun methods included metallo- and serine proteases, phospholipases, oxidases, and Kunitz trypsin inhibitors, along with many other components at lower qualitative abundance. This study provides a more detailed understanding of the protein profile of Iranian P. persicus venom, which can be effective in the production of an effective antidote against it. The analysis of the resulting data shows that there is a wide range of proteins in the venom of the Persian horned viper. This information can provide a better understanding of how venom is neutralized by polyclonal antivenom. Considering the wide presence of this snake and its related species in Iran and surrounding countries, knowing the venom protein profile of this family can be of great support to antivenom producers such as Razi Vaccine & Serum Research Institute in the preparation of regional antivenoms.

Simultaneous quantification of 4-hydroxytamoxifen and hesperidin in liposomal formulations: Development and validation of a RP-HPLC method

Breast cancer treatment options are diverse, with tamoxifen commonly used as a selective estrogen receptor modulator (SERM) for hormone receptor-positive breast cancer. However, tamoxifen can have adverse systemic effects. Local transdermal therapy offers a potential solution by delivering the drug directly to the breast and minimizing systemic exposure. Hesperidin, a flavonoid, exerts synergistic effects when combined with anticancer agents. This combination therapy may be a more effective approach to breast cancer management. Analytical methods have been developed to quantify 4-Hydroxytamoxifen (4-HT) and hesperidin separately; however, no method currently exists for their simultaneous quantification in pharmaceutical formulations. This study aimed to develop and validate a reverse-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous quantification of 4-HT and hesperidin in liposomal formulations. A Design of Experiments (DoE) approach was employed using a Box-Behnken design (BBD) to optimize the RP-HPLC method. BBD allowed for a reduction in the number of required tests by creating a statistical model to estimate the significance of various factors and interactions. The methanol concentration, flow rate, and injection volume were considered as independent variables for optimization. A mobile phase (90:10 ratio of methanol: 0.1% v/v orthophosphoric acid) with a flow rate of 0.4 mL/min, and an injection volume of 10 μL was selected as optimized chromatographic condition. 4-HT showed a retention time (Rt) of 5.05 min and hesperidin showed an Rt of 7.11 min using an optimized analytical method and was detected at 275 nm. The developed RP-HPLC method was validated according to the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines, confirming its accuracy, precision, linearity, selectivity, and robustness. The validated method was then successfully applied to determine the entrapment efficiency and permeation of 4-HT and hesperidin into loaded liposomes. This study fills a gap in the literature by providing a simple and reliable RP-HPLC method for the simultaneous quantification of 4-HT and hesperidin in liposomal formulations.

Analytical Method Development and Validation: Quantitative Estimation for Assay of Revefenacin in Pharmaceutical Dosage form by RP-HPLC method

Revefenacin is a medication for the treatment of chronic obstructive pulmonary disease (COPD). A simple, accurate and precise reversed-phase high-performance-liquid-chromatography (RP-HPLC) method was developed and validated for Revefenacin in bulk and pharmaceutical dosage forms. The method was optimized by selecting chromatographic conditions of 30:70 v/v, 0.2% Perchloric acid solution: Acetonitrile used as a mobile-phase, Inertsil® column ODS-3V (4.6mm* 25 cm, 5μm), injection volume 20μL, flow-rate 1.0ml/min at an ambient temperature of column oven (25°C), auto-sampler temperature 15°C and λmax 242nm. A different column of C18-Kinetex F-5 (4.6mm* 25 cm, 5μm) was also examined, reporting no significant divergence in the results obtained. The method was further validated, giving good precision (%RSD/CV&lt;1.0) and acceptable linearity (r≥0.999) on both columns. The pharmaceutical revefenacin drug offers a high recovery rate of 99.77%. The proposed method is observed as simple, rapid and economical and can be employed for routine analysis in quality control laboratories.

Assessment of bioactive peptides derived from laminin-111 as prospective breast cancer-targeting agents

Breast cancer remains a pressing public health issue primarily affecting women. Recent research has spotlighted bioactive peptides derived from laminin-111, implicated in breast tumor development. Remarkably, the sequences IKVAV, YIGSR, and KAFDITYVRLKF from the α1, β1, and γ1 chains, respectively, have garnered significant attention. This study aims to assess the potential of these radiolabeled peptides as targeting agents for breast cancer. The three peptides were synthesized using the Fmoc strategy, purified via reversed-phase high-performance liquid chromatography (RP-HPLC), and characterized through mass spectrometry. Iodine-131 (131I) radiolabeling was performed using the chloramine T method, exhibiting high radiochemical yield and stability for [131I]I-YIKVAV and [131I]I-YIGSR. Conversely, [131I]I-KAFDITYVRLKF demonstrated low radiochemical yield and stability and was excluded from the biological studies. The lipophilicity of the compounds ranged from − 2.12 to − 1.10. Serum protein binding assay for [131I]I-YIKVAV and [131I]I-YIGSR reached ≅ 48% and ≅ 25%, respectively. Affinity for breast cancer cells was evaluated using MDA-MB-231 and MCF-7 tumor cell lines, indicating the affinity of the radiopeptides with these tumor cells. Ex vivo biodistribution profiles of the radiopeptides were assessed in the MDA-MB-231 breast tumor animal model, revealing tumor tissue accumulation, supported by a high tumor-to-contralateral muscle ratio and autoradiography. These results signify the effective penetration of YIKVAV and YIGSR into tumor tissue. Therefore, the synthesized α1 and β1 peptide fragments exhibit favorable characteristics as potential breast cancer-targeting agents, promising future exploration as radiopharmaceuticals for breast cancer.

Study of the Dynamics of Diflunisal Release from a Polymer Matrix

Introduction. The effectiveness of diflunisal in the treatment of cardiac amyloidosis has been clinically proven. Currently, only tablet forms of diflunisal are registered in the world, however, long-term use of NSAIDs leads to characteristic side effects. Therefore, delivery systems for diflunisal (including a form for external use) are now being actively developed to reduce side effects and improve its bioavailability.Aim. Research of the dynamics of release of the active substance diflunisal from the polymer matrix of hyaluronic acid.Materials and methods. The objects of the study are diflunisal gels in hyaluronic acid with a concentration of the main substance of 0.093, 0.14, 0.19 and 0.25 %. Quantitative determination was carried out by reverse-phase HPLC using a Prontosil C18, 120-5, 75 × 2 mm chromatographic column, thermostatically controlled at 40 °C. Eluent: phosphate buffer solution (PBS) with pH 3.0 and acetonitrile (30 : 70), flow rate 0.1 ml/min. Eluates were detected at wavelengths of 230, 270, 310 nm.Results and discussion. During the work, a method (HPLC) was selected and a method for determining diflunisal in a HA matrix was developed. The delivery system under study significantly increases the solubility of diflunisal in an aqueous solution compared to the dissolution of the substance. The release of the active substance from the matrices was carried out in a phosphate buffer solution with pH 7.6. The release rate for all samples exceeded 90 % after 3 hours after the start of the experiment, with most of the active substance released within an hour.Conclusion. The data obtained suggest that the release profile is characteristic of biodegradable matrices and diffusion-controlled delivery systems. Complete extraction of diflunisal from HA was achieved using PBS with pH 7.6 as a dissolution medium.

Validation of an Ion-Pair Reverse Phase High-Performance Liquid Chromatography Method for the Detection of Major Components and Related Substances in Diquafosol Sodium Eye Drops.

A simple, feasible, isocratic elution, and stable reversed-phase high performance liquid chromatography method was established and verified. The chromatographic conditions are as follows: EF-C18H, 4.6 × 250 mm, 5 μm column; column temperature 30 °C; for the mobile phase 27.2 g of KH2PO4 and 8.5 g of tetrabutylammonium hydrogen sulfate were taken, 2500 mL of water was added to dissolve, and the pH was adjusted to 6.7 with phosphoric acid:methanol solution with a ratio of 84:16 (V:V). The flow rate was 1.0 mL/min; the injection volume was 10 μL; and the wavelength was 262 nm. According to the current ICH guidelines, the developed method was verified, and the system suitability, specificity, LOD, LOQ, linearity, range, accuracy, repeatability, durability, and solution stability of the proposed method were verified. The validation results demonstrated that the LOQ for the method was 0.05% and the LOD was 0.02%. The content was detected within the concentration range of 300 to 900 μg/mL. The relationship between concentration and measurement was linear, with an r2 of >0.999. The concentration of impurities ranged from 0.3 to 4.5 μg/mL. A good linear correlation was observed within the range of g/mL, with a coefficient of determination r2 greater than 0.999. The accuracy and repeatability met the specified criteria.

“A Comprehensive Review on Selective Dual Inhibitor NSAID - Polmacoxib”

The review article provides extensive overview on the promising pharmaceutical compound, polmacoxib also known as CG100649, explaining its pharmacological properties, chemical and physical properties, clinical studies and analytical methods. Polmacoxib is a novel nonsteroidal anti-inflammatory drug (NSAID) that has shown significant interest in recent years for its potential therapeutic benefits in Osteoarthritis treatment and distinct analytical characteristics. The chemical and pharmacological section in this review depicts the choice of solvents to be used through its solubility profile and the mechanism of action which focuses on inhibition of both cyclooxygenase-2 (COX-2) and carbon anhydrase inhibition with subsequent modulation of prostaglandin synthesis. The clinical trial of polmacoxib shows especially the phase 3 trial explains majorly about the safety and efficacy of the drug and explains why it is the chosen one among other NSAIDs. Data from randomized controlled trials and observational studies provides understanding of its use in patient population, expressing its potential as an alternate NSAID. Analytical methods for polmacoxib, such as Reverse Phase High Performance Liquid Chromatography (RP-HPLC), Differential Scanning Calorimetry (DSC), and Powder X-Ray Diffraction (PXRD) are highlighted in this review. The RP-HPLC is developed for quantification of drug, while DSC and PXRD reveals about the solid-state property of CG100649 which will be useful in formulation and stability studies. In conclusion, this review article provides critical information regarding the drug Polmacoxib with its chemical and pharmacological properties, trials conducted as well as analytical procedures performed. It would clearly serve as a valuable resource for analysts, clinicians, researchers and pharmaceutical professionals in understanding its potential and performing further in-process manufacturing and drug product development

Self-Assembly of a Novel Pentapeptide into Hydrogelated Dendritic Architecture: Synthesis, Properties, Molecular Docking and Prospective Applications.

Currently, ultrashort oligopeptides consisting of fewer than eight amino acids represent a cutting-edge frontier in materials science, particularly in the realm of hydrogel formation. By employing solid-phase synthesis with the Fmoc/tBu approach, a novel pentapeptide, FEYNF-NH2, was designed, inspired by a previously studied sequence chosen from hen egg-white lysozyme (FESNF-NH2). Qualitative peptide analysis was based on reverse-phase high performance liquid chromatography (RP-HPLC), while further purification was accomplished using solid-phase extraction (SPE). Exact molecular ion confirmation was achieved by matrix-assisted laser desorption-ionization mass spectrometry (MALDI-ToF MS) using two different matrices (HCCA and DHB). Additionally, the molecular ion of interest was subjected to tandem mass spectrometry (MS/MS) employing collision-induced dissociation (CID) to confirm the synthesized peptide structure. A combination of research techniques, including Fourier-transform infrared spectroscopy (FTIR), fluorescence analysis, transmission electron microscopy, polarized light microscopy, and Congo red staining assay, were carefully employed to glean valuable insights into the self-assembly phenomena and gelation process of the modified FEYNF-NH2 peptide. Furthermore, molecular docking simulations were conducted to deepen our understanding of the mechanisms underlying the pentapeptide's supramolecular assembly formation and intermolecular interactions. Our study provides potential insights into amyloid research and proposes a novel peptide for advancements in materials science. In this regard, in silico studies were performed to explore the FEYNF peptide's ability to form polyplexes.