An overview of experimental designs in HPLC method development and validation

Application of experimental design as a statistical approach to recover bioactive peptides from different food sources

Bioactive peptides (BAPs) derived from samples of animals and plants have been widely recommended and consumed for their beneficial properties to human health and to control several diseases. This work presents the applications of experimental designs (DoE) used to perform factor screening and/or optimization focused on finding the ideal hydrolysis condition to obtain BAPs with specific biological activities. The collection and discussion of articles revealed that Box Behnken Desing and Central Composite Design were the most used. The main parameters evaluated were pH, time, temperature and enzyme/substrate ratio. Among vegetable protein sources, soy was the most used in the generation of BAPs, and among animal proteins, milk and shrimp stood out as the most explored sources. The degree of hydrolysis and antioxidant activity were the most investigated responses in obtaining BAPs. This review brings new information that helps researchers apply these DoE to obtain high-quality BAPs with the desired biological activities.

Establishment and application of a screening method for α-glucosidase inhibitors based on dual sensing and affinity chromatography

α-Glucosidase plays a direct role in the metabolic pathways of starch and glycogen, any dysfunction in its activity could result in metabolic disease. Concurrently, this enzyme serves as a target for diverse drugs and inhibitors, contributing to the regulation of glucose metabolism in the human body. Here, an integrated analytical method was established to screen inhibitors of α-glucosidase. This step-by-step screening model was accomplished through the biosensing and affinity chromatography techniques. The newly proposed sensing program had a good linear relationship within the enzyme activity range of 0.25 U mL-1 to 1.25 U mL-1, which can quickly identify active ingredients in complex samples. Then the potential active ingredients can be captured, separated, and identified by an affinity chromatography model. The combination of the two parts was achieved by an immobilized enzyme technology and a microdevice for reaction, and the combination not only ensured efficiency and accuracy for inhibitor screening but also eliminated the occurrence of false positive results in the past. The emodin, with a notable inhibitory effect on α-glucosidase, was successfully screened from five traditional Chinese medicines using this method. The molecular docking results also demonstrated that emodin was well embedded into the active pocket of α-glucosidase. In summary, the strategy provided an efficient method for developing new enzyme inhibitors from natural products.

Design of experiment-oriented development and validation of novel bioanalytical reverse phase high performance liquid chromatography method of palbociclib in rat plasma and tissues, and its application in pharmacokinetic studies

The current research involved the development and validation of an easy, cost-effective, and sensitive bioanalytical reverse-phase high-performance liquid chromatography method for the assessment of palbociclib (PAL) in rat plasma and kidney, liver, spleen and heart. A response surface methodology-based Box-Behnken design was used to optimize critical chromatographic conditions such as buffer pH, organic phase concentration and flow rate to attain good sensitivity, tailing factor and retention time. The conditions were: pH of buffer, 4.5; organic phase concentration, 40%; Shimpac column with 1.0 ml/min flow rate. The responses were: tailing factor, 1.29 ± 0.03, sensitivity, 366,593 ± 8,592; and retention time, 4.5 ± 0.05 min. The samples were extracted by a protein precipitation method, and absolute recoveries were in the range of 88.99-95.08%. The linearity of the developed method was validated over the range 100-2,000 ng/ml (r2  ≥ 0.994) in all tested matrices. The developed bioanalytical method showed greater accuracy (0.98 and 4.01%) and precision (<4.88%). The method was optimized for the sensitive analysis of the PAL in rat plasma, and the kidney, liver, spleen and heart were effectively applied to pharmacokinetic studies.

Analyzing Alkyl Bromide Genotoxic Impurities in Febuxostat Based on Static Headspace Sampling and GC-ECD

Herein, a sensitive and selective gas chromatography-electron capture detector (GC-ECD) method was developed and validated for the quantification of trace levels of five bromo-containing genotoxic impurities in Febuxostat active pharmaceutical ingredient (API) after headspace sampling (HS). Multivariate experimental designs for the optimization of static headspace parameters were conducted in two stages using fractional factorial design (FFD) and central composite design (CCD). The optimum headspace conditions were 5 min of extraction time and a 120 °C extraction temperature. Baseline separation on the analytes against halogenated solvents was carried out using an Agilent DB-624 (30 m × 0.32 mm I.D., 1.8 μm film thickness) stationary phase under isothermal conditions. The method was validated according to ICH guidelines in terms of specificity, linearity, the limits of detection and quantification, precision and accuracy. The linearity was assessed in the range of 5-150% with respect to the specification limit. The achieved LOD and LOQ values ranged between 0.003 and 0.009 and 0.01 and 0.03 μg mL-1, respectively. The accuracy of the method (expressed as relative recovery) was in the range of 81.5-118.2%, while the precision (repeatability, inter-day) was less than 9.9% in all cases. The validated analytical protocol has been successfully applied to the determination of the impurities in various Febuxostat API batch samples.

LC-MS/MS method for simultaneous estimation of raloxifene, cladrin in rat plasma: application in pharmacokinetic studies

Aim: A newer LC-MS/MS method was developed and validated for the simultaneous quantification of raloxifene (RL) and cladrin (CL). Methodology: Both drugs were resolved in RP-18 (4.6 × 50 mm, 5 μ) Xbridge Shield column using acetonitrile and 0.1% aqueous solution of formic acid (FA) (70:30% v/v) as mobile phase by using biological matrices in female Sprague-Dawley rats using-MS/MS. Results: The developed method was found to be linear over the concentration ranges of 1-600 ng/ml, and lower limit of quantification was 1 ng/ml for RL and CL, respectively. Pharmacokinetic results of RL+CL showed Cmax = 4.23 ± 0.61, 26.97 ± 1.14 ng/ml, at Tmax(h) 5.5 ± 1.00 and 3.5 ± 1.00, respectively. Conclusion: Pharmacokinetic study results will be useful in the future for the combined delivery of RL and CL for osteoporosis treatment.

Optimization and validation of a bioanalytical HPLC-UV technique for simultaneous determination of underivatized phenylalanine and tyrosine in the blood for phenylketonuria diagnosis and monitoring

This study aimed to develop a fast, accurate, and precise high-performance liquid chromatography with UV detection method for simultaneous analysis of underivatized phenylalanine (Phe) and tyrosine (Tyr) in biological samples. Separation of the analytes was accomplished using a Discovery HS F5-3 column, which offered better retention and peak symmetry for the tested analytes. Chromatographic conditions were optimized using central composite experimental design, and three factors were investigated: the concentration of ammonium acetate (A), the acetonitrile proportion in the mobile phase (B) and the column oven temperature (C). The approach was verified using β-expectation tolerance intervals for total error measurement that did not exceed 15%. Optimal settings were A = 50 mm, B = 24% and C = 28°C. The method applicability was determined using human plasma from 75 volunteers. The limits of detection and quantification of the technique were satisfactory at 9 and 29 μm for Phe and 4 and 13 μm for Tyr. The mean analytical bias in spiking levels was acceptable, ranging from -1.649 to +1.659% for both substances, with RSD <5% in all instances. The suggested approach was successfully used to analyze Phe and Tyr in human blood samples and calculate the Phe/Tyr ratio.

Retention Time Prediction through Learning from a Small Training Data Set with a Pretrained Graph Neural Network

Graph neural networks (GNNs) have shown remarkable performance in predicting the retention time (RT) for small molecules. However, the training data set for a particular target chromatographic system tends to exhibit scarcity, which poses a challenge because the experimental process for measuring RT is costly. To address this challenge, transfer learning has been used to leverage an abundant training data set from a related source task. In this study, we present an improved transfer learning method to better predict the RT of molecules for a target chromatographic system by learning from a small training data set with a pretrained GNN. We use a graph isomorphism network as the architecture of the GNN. The GNN is pretrained on the METLIN-SMRT data set and is then fine-tuned on the target training data set for a fixed number of training iterations using the limited-memory Broyden-Fletcher-Goldfarb-Shanno optimizer with a learning rate decay. We demonstrate that the proposed method achieves superior predictive performance on various chromatographic systems compared with that of the existing transfer learning methods, especially when only a small training data set is available for use. A potential avenue for future research is to leverage multiple small training data sets from different chromatographic systems to further enhance the generalization performance.

Exquisite integration of quality-by-design and green analytical approaches for simultaneous determination of xylometazoline and antazoline in eye drops and rabbit aqueous humor, application to stability study

This work implements a stability indicating HPLC method developed to simultaneously determine xylometazoline (XYLO) and antazoline (ANT) in their binary mixture, rabbit aqueous humor and cited drug's degradates by applying analytical quality-by-design (AQbD) combined with green analytical chemistry (GAC) experiment for the first time. This integration was designed to maximize efficiency and minimize environmental impacts, as well as energy and solvent consumption. Analytical quality-by-design was applied to achieve our aim starting with evaluation of quality risk and scouting analysis, tracked via five parameters chromatographic screening using Placket-Burman design namely: pH, temperature, organic solvent percentage, flow rate, and wavelength detection. Recognizing the critical method parameters was done followed by optimization employing central composite design and Derringer's desirability toward assess optimum conditions that attained best resolution with satisfactory peak symmetry with short run time. Optimal chromatographic separation was attained by means of an XBridge® C18 (4.6 × 250 mm, 5 µm) column through isocratic elution using a mobile phase consists of phosphate buffer (pH 3.0): ethanol (60:40, by volume) at a 1.6 mL/min flow rate and 230.0 nm UV detection. Linearity acquired over a concentration range of 1.0-100.0 µg/mL and 0.5-100.0 µg/mL for XYLO and ANT, respectively. Furthermore, imperiling cited drugs' stock solutions to stress various conditions and satisfactory peaks of degradation products were obtained indicating that cited drugs are vulnerable to oxidative degradation and basic hydrolysis. Degradates' structures were elucidated using mass spectrometry. Applying various assessment tools; namely: analytical greenness (AGREE), green analytical procedure index (GAPI), analytical eco-scale, and national environmental method index (NEMI), Greenness method's evaluation was applied and proved to be green. In fact, the developed method is established to be perceptive, accurate, and selective to assess cited drugs for routine analysis.

Plackett-Burman and face-centered composite designs for development and optimization of chromatographic method for the simultaneous determination of glycopyrronium, indacaterol and mometasone in their fixed dose combination inhaler - Green profile assessment

A novel simple, specific, sensitive, accurate and precise reversed phase high performance liquid chromatographic method (RP-HPLC/UV) was developed and validated for the simultaneous estimation of Glycopyrronium bromide (GLY), Indacaterol acetate (IND) and Mometasone furoate (MOF) in pure form, in laboratory prepared mixtures and in pharmaceutical dosage form. Experimental design methodology was applied by using Plackett-Burman and face-centered composite designs to achieve the best resolution with minimum experimental trials. The designed model was statistically analyzed, graphically presented by surface plots and the relationships between coefficients of the derived polynomial equations were interpreted. Chromatographic separation was achieved on Inertsil ODS C18 column (250 ×4.6 mm, 5 µm) at ambient temperature using a mobile phase composed of methanol: 0.1% glacial acetic acid (pH4) in a gradient elution at a flow rate 1 mL /min. UV detection was carried out at 233 nm. Response was found to be linear in the concentration range of 20-120 µg /mL with regression coefficient (r2 = 0.999) for GLY, 50-300 µg /mL with regression coefficient (r2 = 0.9995) for IND and 50-300 µg /mL with regression coefficient (r2 = 0.9998) for MOF. The method was validated as per ICH guidelines and satisfactory results were achieved. The method was successfully applied for the analysis of the cited drugs in their fixed dose combination (FDC) pharmaceutical formulation. Statistical comparison between the results obtained by the proposed method and the reference methods for GLY, IND and MOF showed no significant difference. The developed method could be implemented in quality control aspects of the cited drugs. Four green metrics were used to evaluate the new RP-HPLC/UV method's greenness and compare it to other published techniques.

Drilling into "Quality by Design" Approach for Analytical Methods

The need for consistency in analytical method development reinforces the dependence of pharmaceutical product development and manufacturing on robust analytical data. The Analytical Quality by Design (AQbD), akin to the product Quality by Design (QbD) endows a high degree of confidence to the method quality developed. AQbD involves the definition of the analytical target profile as starting point, followed by the identification of critical method variables and critical analytical attributes, supported on risk assessment and design of experiment tools for the establishment of a method operable design region and control strategy of the method. This systematic approach moves away from reactive troubleshooting to proactive failure reduction. The objective of this review is to highlight the elements of the AQbD framework and provide an overview of their implementation status in various analytical methods used in the pharmaceutical field. These methodologies include but are not limited to, high-performance liquid chromatography, UV-Vis spectrophotometry, capillary electrophoresis, supercritical fluid chromatography, and high-performance thin-layer chromatography. Finally, a critical appraisal is provided to highlight how regulators have encouraged AQbD principles application to boost the prevention of method failures and a better understanding of the method operable design region (MODR) and control strategy, ultimately resulting in cost-effectiveness and regulatory flexibility.

Enrichment Extraction and Activity Study of the Different Varieties of Hericium erinaceus against HCT-8 Colon Cancer Cells

Hericium erinaceus (HE), a widely utilized natural remedy and dietary source, has garnered significant attention for its therapeutic potential in various diseases. In this study, we employed supercritical fluid extraction (SFE) technology to isolate the bioactive compounds from HE's fruiting body. Comprehensive assessments of the antioxidant and antibacterial activities were conducted, along with in vitro investigations on the human colon cancer cell line (HCT-8). The SFE rate served as the evaluation metric, while the variables of extraction time, pressure, and temperature were systematically examined. By integrating the response surface center composite design, we successfully optimized the extraction process, yielding optimal parameters of 80 min, 30 MPa, and 35 °C, thus resulting in an extraction rate of 2.51%. These optimized conditions exhibited considerable antioxidant capacity, anticancer activity, and antibacterial potential. Furthermore, we employed graded alcohol extraction to refine the crude extracts, thereby confirming superior anticancer effects under a 70% alcohol precipitation. To elucidate the composition, Fourier-transform infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC-MS) were employed to analyze the crude extracts and isolates of HE, facilitating a comparative analysis of six HE varieties. Our findings suggest that sterol derivatives hold promise as the active component against the colon cancer HCT-8 cell line. In conclusion, this study underscores the potential of HE SFE in the development of functional foods or alternative drugs for colon cancer treatment, thus opening new avenues for therapeutic interventions.

Investigating Perampanel Antiepileptic Drug by DFT Calculations and SERS with Custom Spinning Cell

SERS, a clinical practice where medical doctors can monitor the drug concentration in biological fluids, has been proposed as a viable approach to therapeutic drug monitoring (TDM) of the antiepileptic drug Perampanel. The adoption of an acidic environment during the SERS experiments was found to be effective in enhancing the spectroscopic signal. In this work, we combine SERS experiments, conducted with a custom spinning cell in controlled acidic conditions, with DFT calculations aimed at investigating the possible protonated forms of Perampanel. The DFT-simulated Raman spectra of protonated Perampanel accounts for most of the observed SERS signals, thus explaining the effective role of protonation of the analyte. Our results suggest protonation as a viable approach to fostering SERS of alkaline drugs.

Development and validation of simultaneous quantification method for gemcitabine and betulinic acid: augmenting industrial application

Combinatorial treatment utilizing a nucleoside analogue gemcitabine (GEM), with a characteristic pentacyclic triterpenoid betulinic acid (BET), has exhibited empowering adequacy in the therapy of cancer. It lessens the advancement of collagen and upgrades the saturation of tumour medicines. With the advancement in nanotechnology, the co-loaded formulation urges for a validated method of estimation. The purposed work entails a robust, simple, and economical analytical method for the simultaneous estimation of GEM and BET through RP-HPLC. Orthophosphoric acid (0.1%)-acetonitrile was considered as the mobile phase for the detection of GEM and BET at 248 nm and 210 nm with retention times of 5 min and 13 min, respectively. The method was further validated as per the regulatory guidelines with all the parameters found within the limit. The developed method with adequate resolution and quantification was found to be linear, accurate, precise, robust, and stable with an intra- and inter-day variability of less than 2%. The method was found specific for GEM and BET with no matrix interference of drug-spiked FBS samples. To demonstrate the applicability of the developed method, a nano-formulation containing GEM and BET was prepared and assessed for various parameters including encapsulation efficiency, loading efficiency, drug release, and drug stability. The method developed can be a possible tool for the simultaneous quantification of GEM-BET in analytical and biological samples.

Amazonia Phytotherapy Reduces Ischemia and Reperfusion Injury in the Kidneys

Acute kidney injury (AKI) is defined as a sudden decrease in kidney function. Phytomedicines have shown positive effects in the treatment of AKI worldwide. The aim of this study was to evaluate the effect of Abuta grandifolia on the renal function of rats submitted to AKI. A phytochemical study of the plant was performed through liquid chromatography coupled with mass spectrometry (CL-EM) and DPPH and ABTS antioxidant tests. Renal function tests were performed in 20 male adult Wistar rats weighing from 250 to 300 g distributed in the following groups: SHAM (submitted to laparotomy with simulation of renal ischemia); ABUTA (animals that received 400 mg/kg of AG, orally-VO, once a day, for 5 days, with simulation of renal ischemia); I/N (animals submitted to laparotomy for clamping of bilateral renal pedicles for 30 min, followed by reperfusion); ABUTA + I/R (animals that received AG-400 mg/kg, 1× per day, VO, for 5 days, submitted to renal ischemia after treatment with herbal medicine). The results suggest that the consumption of Abuta grandifolia promoted renoprotection, preventing the reduction of renal function induced by ischemia, oxidizing activity, and deleterious effects on the renal tissue, confirmed by the decrease of oxidative metabolites and increase of antioxidants in the animals' organisms.

Phytobioactive compounds as therapeutic agents for human diseases: A review

Phytobioactive compounds are plant secondary metabolites and bioactive compounds abundantly present in medicinal plants and have remarkable therapeutic potential. Oxidative stress and antibiotic resistance are major causes of present-day ailments such as diabetes, atherosclerosis, cardiovascular disorders, cancer, and inflammation. The data for this review were collected from Google Scholar, PubMed, Directory of Open Access Journals (DOAJ), and Science Direct by using keywords: "Medicinal plants, Phytobioactive compounds, Polyphenols, Alkaloids, Carotenoids etc." Several studies have reported the pharmacological and therapeutic potential of the phytobioactives. Polyphenols, alkaloids, terpenes, and polysaccharides isolated from medicinal plants showed remarkable antioxidant, anticancer, cytotoxic, anti-inflammatory, cardioprotective, hepatoprotective, immunomodulatory, neuroprotective, and antidiabetic activities. This literature review was planned to provide comprehensive insight into the biopharmacological and therapeutic potential of phytobioactive compounds. The techniques used for the extraction and isolation of phytobioactive compounds, and bioassays required for their biological activities such as antioxidant, antimicrobial, anti-inflammatory, and cytotoxic activities, have been discussed. Characterization techniques for the structural elucidation of phytobioactive compounds such as HPLC, TLC, FTIR, GC-MS/MS, and NMR have also been discussed. This review concludes that phytobioactive compounds may be used as potential alternative to synthetic compounds as therapeutic agents for the treatment of various diseases.

Optimization of silver nanoparticles synthesis by chemical reduction to enhance SERS quantitative performances: Early characterization using the quality by design approach

Surface-enhanced Raman scattering (SERS) is a vibrational widely used technique thanks to its multiple advantages such as its high specificity and sensitivity. The Raman signal exaltation comes from the use of metallic nanoparticles (Nps) acting as antennas by amplifying the Raman scattering. Controlling the Nps synthesis is a major point for the implementation of SERS in routine analysis and especially in quantitative applications. Effectively, nature, size and shape of these Nps considerably influence the SERS response intensity and repeatability. The Lee-Meisel protocol is the most common synthesis route used by the SERS community due to the low cost, rapidity and ease of manufacturing. However, this process leads to a significant heterogeneity in terms of particle size and shape. In this context, this study aimed to synthesize repeatable and homogeneous silver nanoparticles (AgNps) by chemical reduction. The Quality by Design strategy from quality target product profile to early characterization design was considered to optimize this reaction. The first step of this strategy aimed to highlight critical parameters by the means of an early characterization design. Based on an Ishikawa diagram, five process parameters were studied: the reaction volume as categorical variable and the temperature, the time of reaction, the trisodium citrate concentration and pH as continuous variables. A D-Optimal design of 35 conditions was performed. Three critical quality attributes were selected to maximize the SERS intensity, minimize the variation coefficient on SERS intensities and the polydispersity index of the AgNps. Considering these factors, it appeared that concentration, pH and time of reaction were identified as having a critical impact on the Nps formation and can then be considered for the further optimization step.

Fabrication of porous cobalt oxide/carbon nanopolks on electrospun hollow carbon nanofibers for microextraction by packed sorbent of parabens from human blood

In this work, electrospinning and hydrothermal methods were employed to synthesize an innovative 3D Co₃O₄/C@HCNFs nanocomposite as the sorbent. It was then used in a packed sorbent microextraction system for parabens analysis in human blood samples, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The coaxial electrospun core-shell nanofibers mat was stabilized and carbonized to produce the hollow carbon nanofibers (HCNFs) substrate. A coating of cobalt carbonate hydroxide nanopolks was then grown on the HCNFs through hydrothermal synthesis. Ultimately, some of the nanopolks were converted to ZIF-67 by pouring the mat into a warm solution of 2-methyl imidazole and heat-treated into porous Co₃O₄/C afterward. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analyses were used to characterize the produced nanocomposite. The effective parameters of the adsorption and desorption steps were optimized by a central composite design. The figures of merit were evaluated under optimal conditions. The linear range of parabens was obtained between 0.5-500.0 ng ml^-1 with R² ≥ 0.9980. The detection limits of the method were between 0.1 and 0.2 ng ml^-1. The intra-day and inter-day precisions were less than 4.3%. Relative recoveries between 92.0% and 109.3% were achieved. The findings demonstrated the eligible performance of the method.

Chromatographic method development using multivariate approaches for organic solvents optimized analysis in [18F]fluorocholine

A fast and simple method using Gas Chromatography combined with Flame Ionization Detection (GC-FID) was developed for the determination of ethanol, acetonitrile, dibromomethane, dimethylaminoethanol, and dimethyl sulfoxide in [¹⁸F]fluorocholine. The combination of fractional factorial design, Doehlert design, and Desirability function was used to evaluate the operational parameters and to establish the best working condition. The validation results revealed that the proposed method has good recovery (85.1-104.1%) and repeatability (RSD ≤8.1%). Correlation coefficients (R ≥ 0.983) indicated good linearity over a wide range. The limit of detection (≤2.5 ppm) and the limit of quantification (≤7.5 ppm) were satisfactory. The proposed method is based on minimum manual operation, sample preparation free, direct injection technique, and short chromatographic separation time. This method is useful for routine analysis of organic solvents in [¹⁸F]fluorocholine, feasible for the modernization of specific monograph, and was therefore successfully implemented to assess samples manufactured by Nuclear Technology Development Center (CDTN).

Green analytical chemistry and experimental design: a combined approach for the analysis of zonisamide

Green analytical chemistry principles, as well as experimental design, are a combined approach adopted to develop sensitive reproducible stability indicating HPLC method for Zonisamide (ZNS) determination. The optimal conditions for three chromatographic parameters were determined using a central composite design of the response surface. Kromasil C₁₈ column (150 mm × 4.6 mm, 5 µm) was utilized with ethanol, H₂O (30:70 v/v) as a mobile phase at a flow rate of 1 mL/min at 35 °C. Good reproducibility and high sensitivity were achieved along (0.5-10 µg/mL) concentration range. In contrast, the TLC-densitometric method was performed on aluminum plates precoated with silica gel 60F₂₅₄ as a stationary phase and chloroform: methanol: acetic acid (8:1.5:0.5 by volume) as a developing system. Reproducible results were obtained in the range of (2-10 μg/band). The chromatograms of HPLC and TLC were scanned at 280 nm and 240 nm, respectively. The suggested methods have been validated following ICH guidelines, and no statistically significant differences were detected between the results of the current study and the official USP method. It was also found that using experimental design implements the green concept by reducing the environmental impact. Finally, Eco-Scale, GAPI and AGREE were used to assess the environmental impacts of the suggested methods.

Metabolomics and transcriptomics strategies to reveal the mechanism of diversity of maize kernel color and quality

BACKGROUND

Maize has many kernel colors, from white to dark black. However, research on the color and nutritional quality of the different varieties is limited. The color of the maize grain is an important characteristic. Colored maize is rich in nutrients, which have received attention for their role in diet-related chronic diseases and have different degrees of anti-stress protection for animal and human health.

METHODS

A comprehensive metabolome (LC-MS/MS) and transcriptome analysis was performed in this study to compare different colored maize varieties from the perspective of multiple recombination in order to study the nutritional value of maize with different colors and the molecular mechanism of color formation.

RESULTS

Maize kernels with diverse colors contain different types of health-promoting compounds, highlighting that different maize varieties can be used as functional foods according to human needs. Among them, red-purple and purple-black maize contain more flavonoids than white and yellow kernels. Purple-black kernels have a high content of amino acids and nucleotides, while red-purple kernels significantly accumulate sugar alcohols and lipids.

CONCLUSION

Our study can provide insights for improving people's diets and provide a theoretical basis for the study of food structure for chronic diseases.

Exploring the use of the desirability function to optimize the separation of oligonucleotide impurities by ion pair-RP LCMS

The use of small alkyl amines as ion pair reagents permits enhanced separation of impurities of phosphate diester oligonucleotides, which can be beneficial to quality control applications, and aid elucidation of the mechanisms of impurity formation. In general, however, separation of the individual components that comprise the majority of oligonucleotide impurities requires development of several independent chromatographic methods. Ideally, a single method capable of separating the individual components of all impurity classes would be developed. The mathematical concept of the desirability function has been explored here for its ability to determine the combination of experimental factors that result in a single, globally optimized chromatographic method. The optimized mobile phase, consisting of 1 mM propylamine (PA), 30 mM ammonium bicarbonate (ABC), and 1 mM octanoic acid (C8A), produced excellent agreement between measured and predicted peak resolution values for a set of n - 1 impurities. The relative importance of the mobile phase constituents on the mechanism of separation has been discussed. The approach holds great promise for the improved separation of components in complex chromatographic systems.

Establishment of Male and Female Eucommia Fingerprints by UPLC Combined with OPLS-DA Model and Its Application

Eucommia ulmoides Oliver is a dioecious plant, which plays an important role in traditional Chinese medicine. However, there has not yet been any research on male and female E. ulmoides. The UPLC fingerprints and OPLS-DA approach were able to quickly and easily identify and quantify E. ulmoides and differentiate between the male and female fingerprints. In this study, we optimized the UPLC conditions and analyzed them to investigate fingerprints of twenty-four extracts of Eucommiae Cortex (EC) and twenty-four extracts of Eucommiae Folium (EF) under optimal conditions. It was demonstrated that thirteen and twelve substances were possible chemical markers for EC and EF male and female discrimination and that the level of these markers - chlorogenic acid and protocatechuic acid - was many times higher in male than in female. This approach offered a reference for quality control and precise treatment of male and female E. ulmoides in the clinic.

Overview of Analytical Methods for Evaluating Tinidazole

BACKGROUND

Tinidazole (TIN) has amoebicidal, giardicidal, antifungal, and antimicrobial activities. It is marketed in the form of tablets. Analytical methods to assess the quality of TIN-based products are essential for correct pharmacotherapy.

OBJECTIVE

The objective of this review is to show an overview of the existing analytical methods for evaluating TIN, according to the quality control (QC) analysis routine and green analytical chemistry (GAC).

RESULTS

Official compendia show a method for evaluating TIN in tablets by nonaqueous titration, which has limitations (materials on the mg scale using solvents considered not recommended and harmful). The literature shows some analytical methods for evaluating TIN, both physicochemical and microbiological. The most used physicochemical method is UV (41%), and second is HPLC (28%). Among the microbiological methods, agar diffusion and turbidimetric methods are equally divided. The most studied matrix is TIN tablets (73%), and the most used solvent is methanol.

CONCLUSIONS

The literature shows space for the development of analytical methods according to GAC for evaluating TIN, optimizing time, resources, and materials, reducing waste generation, and opting for less aggressive reagents, solvents, and diluents.

HIGHLIGHTS

This review shows the status of analytical methods, both physicochemical and microbiological, for the analysis of TIN in pharmaceutical matrix, in the context of routine analysis of the chemical-pharmaceutical industries and of GAC.

Validation of a New HPLC-DAD Method to Quantify 3-Deoxyanthocyanidins Based on Carajurin in Medicinal Plants and for Chemical Ecology Studies

Anthocyanidins are found in nature mainly as pelargonidin, cyanidin, peonidin, delphinidin, petunidin, and malvidin derivatives. These compounds are found free or as glycoside derivatives which are responsible for the color (red, blue, and violet) of some foods and are responsible for attracting seed dispersers. They are grouped into 3-hydroxyanthocyanidins, 3-deoxyanthocyanidins (3D-anth), and O-methylated anthocyanidins. A new method was developed and validated to quantify 3D-anth in plant-rich extracts. To test the new method, Arrabidaea chica Verlot was selected as it is widely used in folk medicine, and it is rich in 3D-anth. The new method was developed by HPLC-DAD and expressed 3D-anth as carajurin content. Carajurin was chosen as the reference standard due to its role as a biological marker for the antileishmanial activity for A. chica. The selected method used a silica-based phenyl column, a mobile phase composed of potassium dihydrogen phosphate buffer, acetonitrile, and methanol, in a gradient elution mode and detection at 480 nm. The method reliability was confirmed by verifying selectivity, linearity, precision, recovery, and robustness. This method contributes to quality control and development of a possible active pharmaceutical ingredient from A. chica as well as it can be used to evaluate 3D-anth in plant extracts with chemical ecology interest.

The secret of reversed-phase/weak cation exchange retention mechanisms in mixed-mode liquid chromatography applied for small drug molecule analysis

Resolving complex sample mixtures by liquid chromatography in a single run is challenging. The so-called mixed-mode liquid chromatography (MMLC) which combines several retention mechanisms within a single column, can provide resource-efficient separation of solutes of diverse nature. The Acclaim Mixed-Mode WCX-1 column, encompassing hydrophobic and weak cation exchange interactions, was employed for the analysis of small drug molecules. The stationary phase's interaction abilities were assessed by analysing molecules of different ionisation potentials. Mixed Quantitative Structure-Retention Relationship (QSRR) models were developed for revealing significant experimental parameters (EPs) and molecular features governing molecular retention. According to the plan of Face-Centred Central Composite Design, EPs (column temperature, acetonitrile content, pH and buffer concentration of aqueous mobile phase) variations were included in QSRR modelling. QSRRs were developed upon the whole data set (global model) and upon discrete parts, related to similarly ionized analytes (local models) by applying gradient boosted trees as a regression tool. Root mean squared errors of prediction for global and local QSRR models for cations, anions and neutrals were respectively 0.131; 0.105; 0.102 and 0.042 with the coefficient of determination 0.947; 0.872; 0.954 and 0.996, indicating satisfactory performances of all models, with slightly better accuracy of local ones. The research showed that influences of EPs were dependant on the molecule's ionisation potential. The molecular descriptors highlighted by models pointed out that electrostatic and hydrophobic interactions and hydrogen bonds participate in the retention process. The molecule's conformation significance was evaluated along with the topological relationship between the interaction centres, explicitly determined for each molecular species through local models. All models showed good molecular retention predictability thus showing potential for facilitating the method development.

Developing an improved UHPLC method for impurity profile analysis of ceftriaxone using analytical quality by design

In this study, we developed a new reversed-phase ultra-high-performance liquid chromatography (UHPLC) method for comprehensively measuring impurities in ceftriaxone. The method was developed based on the Chinese Pharmacopoeia (ChP) HPLC method, which is limited by the lack of selectivity to potential impurities and a long running time. Screening experiments showed that octylamine concentration, mobile phase pH, and organic phase ratio were critical method parameters. Further optimisation and Monte-Carlo simulations were performed to map out the design space. The selected working conditions resulted in a complete separation of the impurity profile in approximately 10 min. A multivariate approach confirmed that the method was robust, and the proportion of acetonitrile should be carefully controlled. Additionally, the developed UHPLC method could be transferred back to HPLC in a single step using a Columns Calculator, providing a new approach for the rapid and effective development of the HPLC method. Our findings could serve as a reference for developing the next version of the ChP.

Progress and prediction of multicomponent quantification in complex systems with practical LC-UV methods

Complex systems exist widely, including medicines from natural products, functional foods, and biological samples. The biological activity of complex systems is often the result of the synergistic effect of multiple components. In the quality evaluation of complex samples, multicomponent quantitative analysis (MCQA) is usually needed. To overcome the difficulty in obtaining standard products, scholars have proposed achieving MCQA through the "single standard to determine multiple components (SSDMC)" approach. This method has been used in the determination of multicomponent content in natural source drugs and the analysis of impurities in chemical drugs and has been included in the Chinese Pharmacopoeia. Depending on a convenient (ultra) high-performance liquid chromatography method, how can the repeatability and robustness of the MCQA method be improved? How can the chromatography conditions be optimized to improve the number of quantitative components? How can computer software technology be introduced to improve the efficiency of multicomponent analysis (MCA)? These are the key problems that remain to be solved in practical MCQA. First, this review article summarizes the calculation methods of relative correction factors in the SSDMC approach in the past five years, as well as the method robustness and accuracy evaluation. Second, it also summarizes methods to improve peak capacity and quantitative accuracy in MCA, including column selection and two-dimensional chromatographic analysis technology. Finally, computer software technologies for predicting chromatographic conditions and analytical parameters are introduced, which provides an idea for intelligent method development in MCA. This paper aims to provide methodological ideas for the improvement of complex system analysis, especially MCQA.

Structural and antimicrobial property changes of veterinary antibiotics in thermal treatment

Agricultural application contributes major consumption of antibiotics worldwide. As veterinary antibiotics are poorly metabolized by animals, most of them end up in agricultural waste, which is increasingly subject to thermal treatment, such as torrefaction, pyrolysis, etc. However, there is a lack of research on their thermal decomposition mechanisms and products elucidation. Therefore, this study investigated the thermal decomposition of four major veterinary antibiotics groups (β-lactams, tetracyclines, fluoroquinolones, sulfonamides) with emphasis on their thermal stability, structural transformation and antibacterial activity. Results show that thermal treatment can remove the parent antibiotics with their antibacterial activity except for gatifloxacin (GAT). Although the parent form of GAT was fully removed at 200 °C, its products showed significant antibacterial activity against E. coli. We present novel evidence that the PhO-CH₃ chemical bond on GAT preferentially brake to generate methyl radical, which underwent a substitution reaction at the para position of phenol. This reaction also occurred during the thermal decomposition of antibiotic analogues, balofloxacin and moxifloxacin, whose thermolysis products also showed significant antibacterial activity. Furthermore, these thermolysis products may present potentially cardiotoxic and pose higher risks to human health than their parent forms, based on the comparison with a group of drugs withdrawn from the market.

Potential of a novel flagellin epitope as a broad-spectrum vaccine candidate against enteric fever

Relentless emergence of antibiotic resistant Salmonella strains, coupled with the drawbacks associated with currently available vaccines against enteric fever, warrants an urgent need to look for new vaccine candidates. Out of the multiple virulence factors harbored by Salmonella, flagella are regarded as one of the most important targets of innate as well as adaptive immune response. Individual Salmonella serotypes alternate between expression of two different antigenic forms encoded by fliC and fljB genes, respectively thereby employing this as a strategy to escape the host immune response. In the present study, using various immunoinformatic approaches, a flagellin epitope, present in both antigenic forms of typhoidal Salmonellae has been targeted. Following B-cell epitope and B-cell derived T-cell epitope prediction and interaction studies with major histocompatibility complexes using molecular docking, a peptide epitope was selected. Further, it was screened for its presence in majority of typhoidal serovars along with other useful attributes, in silico. Thereafter, safety studies were performed with the synthesized peptide. Subsequently, immunization studies were carried out using S. Typhi as well as S. Paratyphi A induced murine peritonitis model. Active immunization with peptide-BSA conjugate resulted in 75% and 80% mice survival following lethal challenge with S. Typhi and S. Paratyphi A respectively, along with a significant IgG antibody titer, thereby highlighting its immunogenic potential. Reduced bacterial burden in vital organs along with improved histoarchitecture and cytokine levels further substantiated the protective efficacy of the proposed candidate. Passive immunization studies with the candidate verified the protective efficacy of the generated antibodies against lethal challenge of bacteria in mice. Given the endemic nature of enteric fever and the antigenic variability observed in Salmonella serotypes, present study highlights the importance of using a vaccine candidate, which, along with generating a strong immune response, also exhibits a broad coverage against both, S. Typhi as well as S. Paratyphi A strains.

Optimising cell-based bioassays via integrated design of experiments (ixDoE) - A practical guide

For process optimisation Design of Experiments (DoE) has long been established as a more powerful strategy than a One Factor at a Time approach. Nevertheless, DoE is not widely used especially in the field of cell-based bioassay development although it is known that complex interactions often exist. We believe that biopharmaceutical manufacturers are reluctant to move beyond standard practices due to the perceived costs, efforts, and complexity. We therefore introduce the integrated DoE (ixDoE) approach to target a smarter use of DoEs in the bioassay setting, specifically in optimising resources and time. Where in a standard practice 3 to 4 separate DoEs would be performed, our ixDoE approach includes the necessary statistical inference from only a single experimental set. Hence, we advocate for an innovative, ixDoE approach accompanied by a suitable statistical analysis strategy and present this as a practical guide for a typical bioassay development from basic research to biopharmaceutical industry.

The Paradox of Sustainability in Separation Science

In this extended special feature to celebrate the 35th anniversary edition of LCGC Europe, leading figures from the separation science community explore contemporary trends in separation science and identify possible future developments.

Application of experimental design in HPLC method optimisation for the simultaneous determination of multiple bioactive cannabinoids

The scientific interest in Cannabis sativa L. analysis has been rapidly increasing in recent years, especially for what concerns cannabinoids, plant secondary metabolites which are well known for having many biological properties. High-performance liquid chromatography (HPLC) is frequently used for both the qualitative and quantitative analysis of cannabinoids in plant extracts from C. sativa and its derived products. Many studies have been focused on the main cannabinoids, such as ∆⁹-tetrahydrocannabinolic acid (∆⁹-THCA), cannabidiolic acid (CBDA), cannabigerolic acid (CBGA) and their decarboxylated derivatives, such as ∆⁹-tetrahydrocannabinol (∆⁹-THC), cannabidiol (CBD) and cannabigerol (CBG). In addition to the abovementioned compounds, the plant produces other metabolites of the same chemical class, and some of them have shown interesting biological activities. In the light of this, it is important to have efficient analytical methods for the simultaneous separation of cannabinoids, which is quite complex since they present similar chemical-physical characteristics. The present work is focused on the use of the Design of Experiments technique (DoE) to develop and optimise an HPLC method for the simultaneous separation of 14 cannabinoids. Experimental design optimisation was applied by using a Central Composite Face-Centered design to achieve the best resolution with minimum experimental trials. Five significant variables affecting the chromatographic separation, including ammonium formate concentration, gradient elution, run time and flow rate, were studied. A multivariate strategy, based on Principal Component Analysis (PCA) and Partial Least Squared (PLS) regression, was used to define the best operative conditions. The developed method allowed for the separation of 12 out of 14 cannabinoids. Due to co-elution phenomena, HPLC coupled with a triple quadrupole mass analyser (HPLC-ESI-MS/MS) was applied, monitoring the specific transitions of each compound in the multiple reaction monitoring (MRM) mode. Finally, the optimised method was applied to C. sativa extracts having a different cannabinoid profile to demonstrate its efficiency to real samples. The methodology applied in this study can be useful for the separation of other cannabinoid mixtures, by means of appropriate optimisation of the experimental conditions.

Phytochemicals as Potential Inhibitors of Advanced Glycation End Products: Health Aspects and Patent Survey

BACKGROUND

The glycation of proteins and lipids synthesizes the advanced glycation end products (AGEs), i.e., substances that irreversibly damage macromolecules present in tissues and organs, which contribute to the impairment of biological functions. For instance, the accumulation of AGEs induces oxidative stress, the inflammatory responses, and consequently the on set/worsening of diseases, including obesity, asthma, cognitive impairment, and cancer. There is a current demand on natural and low-cost sources of anti-AGE agents. As a result, food phytochemicals presented promising results to inhibit glycation and consequently, the formation of AGEs.

OBJECTIVE

Here we describe how the AGEs are present in food via Maillard reaction and in organs via natural aging, as well as the effects of AGEs on the worsening of diseases. Also we described the methods used to detect AGEs in samples, and the current findings on the use of phytochemicals (phenolic compounds, phytosterols, carotenoids, terpenes and vitamins) as natural therapeuticals to inhibit health damages via inhibition of AGEs in vitro and in vivo.

METHODS

This manuscript reviewed publications available in the PubMed and Science Direct databases dated from the last 20 years on the uses of phytochemicals for the inhibition of AGEs. Recent patents on the use of anti-AGEs drugs were reviewed with the use of Google Advanced Patents database.

RESULTS AND DISCUSSION

There is no consensus about which concentration of AGEs in blood serum should not be hazardous to the health of individuals. Food phytochemicals derived from agroindustry wastes, including peanut skins, and the bagasses derived from citrus and grapes are promising anti-AGEs agents via scavenging of free radicals, metal ions, the suppression of metabolic pathways that induces inflammation, the activation of pathways that promote antioxidant defense, and the blocking of AGE connection with the receptor for advanced glycation endproducts (RAGE).

CONCLUSION

Phytochemicals derived from agroindustry are promising anti-AGEs, which can be included to replace synthetic drugs to inhibit AGE formation, and consequently to act as therapeutical strategy to prevent and treat diseases caused by AGEs, including diabetes, ovarian cancer, osteoporosis, and Alzheimer's disease.

Analytical Quality by Design (AQbD) Approach to the Development of Analytical Procedures for Medicinal Plants

Scientific regulatory systems with suitable analytical methods for monitoring quality, safety, and efficacy are essential in medicinal plant drug discovery. There have been only few attempts to adopt the analytical quality by design (AQbD) strategy in medicinal plants analysis over the last few years. AQbD is a holistic method and development approach that understands analytical procedure, from risk assessment to lifecycle management. The enhanced AQbD approach reduces the time and effort necessary to develop reliable analytical methods, leads to flexible change control through the method operable design region (MODR), and lowers the out-of-specification (OOS) results. However, it is difficult to follow all the AQbD workflow steps in the field of medicinal plants analysis, such as defining the analytical target profiles (ATPs), identifying critical analytical procedure parameters (CAPPs), among others, because the complexity of chemical and biological properties in medicinal plants acts as a barrier. In this review, various applications of AQbD to medicinal plant analytical procedures are discussed. Unlike the analysis of a single compound, medicinal plant analysis is characterized by analyzing multiple components contained in biological materials, so it will be summarized by focusing on the following points: Analytical methods showing correlations within analysis parameters for the specific medicinal plant analysis, plant raw material diversity, one or more analysis targets defined for multiple phytochemicals, key analysis attributes, and analysis control strategies. In addition, the opportunities available through the use of design-based quality management techniques and the challenges that coexist are also discussed.

Design of experiment techniques for the optimization of chromatographic analysis conditions: A review

Design of experiment (DoE) techniques have been widely used in the field of chromatographic parameters optimization as a valuable tool. A systematic literature review of the available DoE techniques applied to the development of a chromatographic analysis method is presented in this paper. First, the most common available designs and the implementation steps of DoE are comprehensively introduced. Then the studies in recent 10 years for the application of DoE techniques in various chromatographic techniques are discussed, such as capillary electrophoresis, liquid chromatography, gas chromatography, thin-layer chromatography, and high-speed countercurrent chromatography. Current problems and future outlooks are finally given to provide a certain inspiration of research in the application of DoE techniques to the different chromatographic techniques field. This review contributes to a better understanding of the DoE techniques for the efficient optimization of chromatographic analysis conditions, especially for the analysis of complex systems, such as multicomponent drugs and natural products.

DoE-assisted development and validation of a stability-indicating HPLC-DAD method for simultaneous determination of five cannabinoids in Cannabis sativa L. based on analytical quality by design (AQbD) concept

INTRODUCTION

Medical uses of Cannabis sativa L. have gained interest in recent decades, which highlights the need for defining appropriate quality specifications for Cannabis-based products. However, the complexity of plant matrices and structural similarity between cannabinoids make analytical development a challenging task. Thus, the application of analytical quality by design (AQbD)-driven approaches can favour the development of fit-for-purpose methods.

OBJECTIVES

To develop a high-performance liquid chromatography diode array detector (HPLC-DAD) method for simultaneous quantification of cannabidiol, Δ⁹ -tetrahydrocannabinol, cannabidiolic acid, tetrahydrocannabinolic acid, and cannabinol in C. sativa by applying an AQbD-driven approach.

MATERIALS AND METHODS

Critical method attributes (CMA) were established following the analytical target profile. Critical method variables (CMV) were categorised based on risk assessment and literature review. Selected CMV regarding sample preparation and chromatographic conditions were optimised using response surface methodology (RSM). The working point was estimated by multiple response optimisation using Deringer's desirability function. The validity of the optimal conditions was confirmed experimentally. Method validation was performed according to ANVISA and ICH guidelines. Relative response factors (RRFs) were also determined.

RESULTS AND DISCUSSION

Baseline resolution of 12 major cannabinoids was achieved in a 35 min chromatographic analysis. All experimental responses obtained during confirmatory analyses were within the prediction intervals (PI_95% ). Method's selectivity, linearity (10-100 μg/mL), precision, bias, extraction recovery, and ruggedness were satisfactorily demonstrated.

CONCLUSIONS

The application of an AQbD-driven approach allowed for a better understanding of the effects of the ensemble of CMV on the analyte's behaviour, enabling the definition of appropriate conditions to ensure consistent achievement of the intended method's performance.

Implementation of QbD Approach to the Development of Chromatographic Methods for the Determination of Complete Impurity Profile of Substance on the Preclinical and Clinical Step of Drug Discovery Studies

The purpose of this work was to demonstrate the use of the AQbD with the DOE approach to the methodical step-by-step development of a UHPLC method for the quantitative determination of the impurity profile of new CPL409116 substance (JAK/ROCK inhibitor) on the preclinical and clinical step of drug discovery studies. The critical method parameters (CMPs) have been tested extensively: the kind of stationary phase (8 different columns), pH of the aqueous mobile phase (2.6, 3.2, 4.0, 6.8), and start (20–25%) and stop (85–90%) percentage of organic mobile phase (ACN). The critical method attributes (CMAs) are the resolution between the peaks (≥2.0) and peak symmetry of analytes (≥0.8 and ≤1.8). In the screening step, the effects of different levels of CMPs on the CMAs were evaluated based on a full fractional design 22. The robustness tests were established from the knowledge space of the screening step and performed by application fractional factorial design 2(4−1). Method operable design region (MODR) was generated. The probability of meeting the specifications for the CMAs was calculated by Monte-Carlo simulations. In relation to literature such a complete AQbD approach including screening, optimization, and validation steps for the development of a new method for the quantitative determination of the full profile of nine impurities of an innovative pharmaceutical substance with the structure-based pre-development pointed out the novelty of our work. The final working conditions were as follows: column Zorbax Eclipse Plus C18, aqueous mobile phase 10 mM ± 1 mM aqueous solution of HCOOH, pH 2.6, 20% ± 1% of ACN at the start and 85% ± 1% of ACN at the end of the gradient, and column temperature 30 °C ± 2 °C. The method was validated in compliance with ICH guideline Q2(R1). The optimized method is specified, linear, precise, and robust. LOQ is on the reporting threshold level of 0.05% and LOD at 0.02% for all impurities.

Quality assessment of African herbal medicine: A systematic review and the way forward

BACKGROUND

In Africa, herbalism supplements allopathic medicine's efforts to ensure Universal Health Coverage attainment. This review was conducted to identify and to summarise current literature on methodological approaches used for quality control of herbal medicines in Africa, to evaluate the gaps associated with existing strategies within context of best practices, and make recommendations for future improvements.

METHODS

A systematic search was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Articles were screened and assessed for eligibility.

RESULTS

118 articles were included into the study. There was a high preference for impurity profiling tests (77%) indicating the prioritization for tests that guarantee safety despite the limited analytical resources available. Other classes of tests reported included identification tests (29%), physicochemical tests (18%), and content assays (12%). Although standard methods exist in preparing samples for impurity tests, different techniques were observed in different studies, and this could lead to differences in analytical outcomes. Content assays focused on single marker assessments, which may be inadequate to comprehensively assess the quality of products.

CONCLUSION

This review provides knowledge of existing strengths and challenges for herbal medicine quality assessments in Africa. For future it is recommended to implement more studies on contaminants (e.g. mycotoxins) and pharmaceutical adulterants. The use of chemometrics to develop analytical methods should be promoted. Also, stakeholders in the medicine quality industry in Africa need to effectively collaborate to establish a well co-ordinated and harmonized system to provide a sustainable framework for the GACP and GMP guided production and quality assurance of herbal medicines.

Solvent strength of organic phase for two biphasic solvent systems in high speed countercurrent chromatography

In this work, relationships between solvent strength of organic phase (ψ) for two biphasic solvent systems in high speed countercurrent chromatography, hexane-ethyl-acetate-methanol-water (HEMWat) and ethyl acetate-n-butanol-water (EBuWat), and partition coefficient (K) were investigated using four retention models, including Jandera's model (ABM), Neue-Kuss model (NK), linear-solvent-strength model (LSS) and quadratic-solvent-strength model (QSS). Experimental results showed that ABM model had the best fitting results for HEMWat system while NK model and QSS model had good fitting results in EBuWat system. Thus, a mathematical relationship between partition coefficient (K) and solvent strength of organic phase (ψ) could be obtained by measurement of partition coefficients of the target compounds with three different volume ratios of organic phase. At the same time, a functional map was proposed to construct to get a maneuverable region so that an optimal two-phase solvent system for separation of a target compound could be selected easily, which saved a lot of manpower for high speed countercurrent chromatographic separation. The application of this new method was declared by successful separation of two components, apigenin-6-C-β-D-xylopyranosyl-8-C-α-L-arabinopyranoside and vicenin-3, from dried leaves of Dendrobium officinale Kimura et Migo using high speed countercurrent chromatography.

The Antimicrobial Activity and Characterization of Bioactive Compounds in Peganum harmala L. Based on HPLC and HS-SPME-GC-MS

Peganum harmala L. is a perennial herb of the Tribulus family and its aerial parts and seeds can be used as medicine in the traditional medicine of China. However, the differences in chemical components and antibacterial activity between different parts have not been reported. In this study, the chemical composition of the different parts of P. harmala was characterized by high-performance liquid chromatography (HPLC) and headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The antimicrobial activities of the different parts and some isolated components were also carried out on 12 bacterial strains and phytopathogenic fungi. The HPLC results revealed that the contents of harmine and harmaline in the seeds were higher than that in the aerial parts. A total of 94 volatile organic compounds (VOCs) were tentatively identified by HS-SPME-GC-MS for the first time. The major components were methyl hexadecanoate, p-xylene, octane, (Z)-9-octadecanoate, ethylbenzene, methyl octadecanoate, ethyl hexadecanoate, and methyl tetradecanoate. At the concentration of 800 μg·mL⁻¹, the methanol extracts of seeds showed stronger antimicrobial activities with a wide antimicrobial spectrum, inhibiting Escherichia coli (ATCC 24433), Xanthomonas oryzae (ACCC 11602), and Xanthomonas axonopodis with inhibitory rates of more than 90%. Furthermore, harmine and harmaline showed better antibacterial activities against all the bacteria. These findings indicated that alkaloids from P. harmala could account for antimicrobial activity, which could be used as lead molecules in the development of new antimicrobial drugs.

Procedure to explore a ternary mixture diagram to find the appropriate gradient profile in liquid chromatography with fluorescence detector. Application to determine four primary aromatic amines in napkins

The purpose of this work is to develop a tool to search for a gradient profile with ternary or binary mixtures in liquid chromatography, that can provide well-resolved chromatograms in the shortest time for multianalyte analysis. This approach is based exclusively on experimental data and does not require a retention time model of the compounds to be separated. The methodology has been applied for the quantification of four primary aromatic amines (PAAs) using HPLC with fluorescence detector (FLD). Aniline (ANL), 2,4-diaminotoluene (TDA), 4,4'-methylenedianiline (MDA) and 2-aminobiphenyl (ABP) have been selected since their importance in food contact materials (FCM). In order to achieve that, partial least squares (PLS) models have been fitted to relate CMP (control method parameters) and CQA (critical quality attributes). Specifically, PLS models have been fitted using 30 experiments for each one of the four CQA (resolution between peaks and total elution time), considering 33 predictor variables (the composition of the methanol and acetonitrile in the mobile phase and the time of each one of the 11 isocratic segments of the gradient). These models have been used to predict new candidate gradients, and then, some of those predictions (the ones with resolutions above 1.5, in absolute value, and final time lower than 20 min) have been experimentally validated. Detection capability of the method has been evaluated obtaining 1.8, 189.4, 28.8 and 3.0 µg L^-1 for ANL, TDA, MDA and ABP, respectively. Finally, the application of chemometric tools like PARAFAC2 allowed the accurate quantification of ANL, TDA, MDA and ABP in paper napkins in the presence of other interfering substances coextracted in the sample preparation process. ANL has been detected in the three napkins analysed in quantities between 33.5 and 619.3 µg L^-1, while TDA is present in only two napkins in quantities between 725.9 and 1908 µg L^-1. In every case, the amount of PAAs found, exceeded the migration limits established in European regulations.

An Experimental Design Approach to Quantitative Expression for Quality Control of a Multicomponent Antidiabetic Formulation by the HILIC Method

A rapid and reproducible hydrophilic liquid chromatography (HILIC) process was established for concomitant determination of remogliflozin etabonate (RE), vildagliptin (VD), and metformin (MF) in a formulation. A face-centered central composite experimental design was employed to optimize and predict the chromatographic condition by statistically studying the surface response model and design space with desirability close to one. A HILIC column with a simple mobile phase of acetonitrile (65% v/v) and 20 mM phosphate buffer (35% v/v, pH 6, controlled with orthophosphoric acid) was used to separate RE, VD, and MF. RE, VD, and MF were separated in 3.6 min using an isocratic mode mobile phase flow at a flow rate of 1.4 mL at room temperature, and the analytes were examined by recording the absorption at 210 nm. The developed HILIC method was thoroughly validated for all parameters recommended by ICH, and linearity was observed in the ranges 20−150 µg/mL, 10−75 µg/mL, and 50−750 µg/mL for RE, VD, and MF, respectively, along with excellent regression coefficients (r2 > 0.999). The calculated percentage relative deviation and relative error ascertained the precision and accuracy of the method. The selectivity and accuracy were further confirmed by the high percentage recovery of added standard drugs to the formulation using the standard addition technique. The robustness of the HILIC processes was confirmed by developing a half-normal probability plot and Pareto chart, as the slight variation of a single factor had no significant influence on the assay outcomes. Utilization of the optimized HILIC procedure for concurrent quantification of RE, VD, and MF in solid dosage forms showed accurate and reproducible results. Hence, the fast HILIC method can be regularly employed for the quality assurance of pharmaceutical preparations comprising RE, VD, and MF.

Quality by design approach for green HPLC method development for simultaneous analysis of two thalassemia drugs in biological fluid with pharmacokinetic study

This work implements a combined experimental approach of analytical quality-by-design (AQbD) and green analytical chemistry (GAC) to develop an HPLC method for simultaneous determination of the two thalassemia drugs, deferasirox (DFX) and deferiprone (DFP), in biological fluid for the first time. This integration was designed to maximize efficiency and minimize environmental impacts, as well as energy and solvent consumption. To accomplish this goal, an analytical quality-by-design approach was performed, beginning with quality risk assessment and scouting analysis, followed by Placket-Burman design screening for five chromatographic parameters. Critical method parameters were thoroughly recognized and then optimized by using a two levels-three factors custom experimental design to evaluate the optimum conditions that achieved the highest resolution with acceptable peak symmetry within the shortest run time. The desirability function was used to define the optimal chromatographic conditions, and the optimal separation was achieved using an XBridge® HPLC RP-C18 (4.6 × 250 mm, 5 μm) column with ethanol : acidic water at pH 3.0 adjusted by phosphoric acid in the ratio of (70 : 30, v/v) as the mobile phase at a flow rate of 1 mL min^-1 with UV detection at 225 nm at a temperature of 25 °C. Linearity was obtained over the concentration range of 0.30-20.00 μg mL^-1 and 0.20-20.00 μg mL^-1 for DFX and DFP, respectively, using 20.00 μg mL^-1 ibuprofen (IBF) as an internal standard. The established method's greenness profile was evaluated and measured using various assessment tools, and the developed method was green. For the validation of the developed method, FDA recommendations were followed, and all the results obtained met the acceptance criteria. The suggested method was successfully used to study the pharmacokinetic parameters of DFX and DFP in rat plasma. Due to the substantial increase in bioavailability of the two iron chelating drugs, the results from this study strongly recommend their co-administration.