Chromatographic Techniques Research Articles

Comparative study of stem bark and small branches of Streblus asper and anti-carcinogenic and anti-diabetic activity

Background: This study focuses on analyzing stigmasterol, a key compound found in Streblus asper lour., in both stem bark and small branches, and investigates its potential as an alternative source. Objective: To analyze the stigmasterol content in both stem bark and small branches of S. asper through High-Performance Liquid Chromatography (HPLC) techniques. In addition, molecular docking studies are conducted to assess the interaction of stigmasterol with selected anticancer and anti-diabetic target proteins. Materials and Methods: The study involved the comparative analysis of stigmasterol content in stem bark and small branches using HPLC techniques. Molecular docking simulations were performed to evaluate the binding affinity of stigmasterol with target proteins associated with anticancer and anti-diabetic activities. Results: HPLC analysis revealed stigmasterol content of 0.13298% in stem bark and 0.0373% in small branches. Molecular docking simulations demonstrated favorable binding energies (−9.0, −12.2, −9.8, −10.5, and −9.5 kcal/mol) of stigmasterol with selected target proteins. Conclusion: Both stem bark and small branches of S. asper contain stigmasterol, indicating their potential as a source of this compound with promising in silico anticancer and anti-diabetic activity. Utilizing small branches could offer a sustainable alternative while conserving the plant species and its ecological balance. Further validation through in vitro and in vivo studies is warranted to explore the therapeutic potential of stigmasterol fully.

Beltanol Sorption Modelling in the Soil Column using High Performance Liquid Chromatography Technique

Beltanol Sorption Modelling in the Soil Column using High Performance Liquid Chromatography Technique

Development and validation of stability-indicating method of etrasimod by HPLC/DAD/MS/MS technique with greenness profiling

Etrasimod, a novel selective sphingosine-1-phosphate receptor modulator, was recently approved by the U.S. Food and Drug Administration and the European Medicinal Agency for the treatment of moderately to severely active ulcerative colitis in adults. In this research, the forced degradation study as an integral part of drug product and packaging development, which generates data on degradation mechanisms, is published. The development and validation of the stability-indicating method using a superior high-performance liquid chromatography technique coupled with a diode array detector and tandem mass spectrometer was performed to support the forced degradation study and monitor the formation of degradation products. Etrasimod demonstrated good stability under elevated temperature and basic stress conditions, while acidic hydrolysis, oxidative, and photolytic degradation produced eight degradation products. The knowledge of degradation products will be useful in the long-term stability study for establishing the acceptance criteria of etrasimod as a drug substance and dosage form during quality control and stability assessment. The eco-friendliness of the developed forced degradation procedure was evaluated using various greenness appraisal tools. The green metric tools showed that the forced degradation procedure obeys eco-friendly conditions.

A review of food contamination with nitrated and oxygenated polycyclic aromatic hydrocarbons: toxicity, analysis, occurrence, and risk assessment.

Prolonged exposure to polycyclic aromatic hydrocarbons (PAHs) and their derivatives, particularly nitrated polycyclic aromatic hydrocarbons (NPAHs) and oxygenated polycyclic aromatic hydrocarbons (OPAHs), can result in adverse health effects and may carry higher toxicity risks compared to PAHs alone. Various extraction methods have been utilized for PAHs derivatives from food samples. The analytes are then analyzed using gas chromatography/mass spectrometry and high-performance liquid chromatography techniques. PAHs derivatives are increasingly being detected in the environment, prompting scrutiny from numerous researchers. Similarly, their presence in food is becoming a significant concern. The elevated levels of PAH derivatives found in smoked food may result in detrimental dietary exposure and pose potential health hazards. Furthermore, investigating the level of exposure to these contaminants in food is imperative, as their consumption by humans carries inherent risks. Consequently, this review concentrates on the toxicity, analysis, occurrence, and risk evaluation of NPAHs and OPAHs present in food sources.

Phytochemical analysis of Robinia pseudoacacia flowers and leaf: quantitative analysis of natural compounds and molecular docking application

Phenolic compounds are widely found and well-known secondary metabolites in plants. Identification, and quantification of phenolic compounds, and determination of their biological activities reveal the unknown secrets of plants. Robinia pseudoacacia (RP) is known as the white-flowered false acacia and is distributed in Northern Anatolia in Turkey. Spectrophotometric and chromatographic techniques are used to identify the presence and amount of phenolics. In this study, RP flowers and leaves were extracted with methanol and analyzed by LC-MS/MS to determine their phytochemical content. Salicylic acid and syringic acid were found as major products in leaves and flowers. RP extracts have been reported to have antibacterial activity and BChE inhibitory properties. Therefore, the BChE and DD peptidase enzyme inhibitory properties of the main components salicylic acid and syringic acid were investigated by molecule docking (MolDock). According to MolDock results, syringic acid interacted with BChE and DD peptidase and was calculated as a MolDock score of -79.38, and -71.25, with binding energies -5.90, and -5.40 kcal/mol respectively. Salicylic acid interacted with BChE and DD peptidase and was calculated as a MolDock score of -63.54, and -66.18, with binding energies of -6.10, and -5.70 kcal/mol respectively. As a result, salicylic acid had higher binding energy in its interactions with BChE and DD peptidase enzymes. In theory, salicylic acid can be used as a good BChE and DD peptidase inhibitor.

Validated Chromatography Method for Analysis of Formaldehyde Migration Levels in Bottled Drinking Water

Polyethylene terephthalate (PET) is utilized in the containment of potable water, nonetheless, it is susceptible to impairment due to temperature and duration of storage. Migration of formaldehyde from PET arises as a consequence of thermal deterioration. This study aims to ascertain the extent of formaldehyde transference in PET-contained drinking water of varying condition, subjected to diverse temperature setting and storage durations. An examination into the levels of formaldehyde migration in polyethylene terephthalate (PET) bottled drinking water was effectively carried out employing a validated high-performance liquid chromatography (HPLC) technique. A total of 162 water samples from three different PET bottled water brands sourced from supermarkets in Palu City, Central Sulawesi, Indonesia, underwent analysis. The formaldehyde assessment was executed utilizing a mobile phase composition of methanol:acetonitrile:water (48:12:40 v/v) for 12.97 minutes at a flow rate of 0.8 mL/minute on the 1st day, the 14th day, and the 42nd day while stored at room temperature and exposed to sunlight. Formaldehyde, lacking effective chromophoric entities and not readily ionizable, necessitated derivatization with 2,4-dinitrophenylhydrazine before HPLC analysis. The findings of the study demonstrated exceptional method linearity within the concentration span of 0.5 to 1321 µg/mL, exhibiting a commendable correlation coefficient of 0.999. The limit of detection (LOD) and quantification (LOQ) were determined to be 17.33 and 57.76 µg/mL, correspondingly. Precision evaluations displayed average intraday and interday values of 128.46±3.48% and 103.19±0.12%, respectively (%RSD < 2/3 CV Horwitz ratio). The intraday and interday %recovery values were computed at 97.22±3.48% and 96.83±0.14% (n = 6). The scrutiny of formaldehyde concentrations in the water samples unveiled the absence of formaldehyde migration.

Phytochemical analysis and the first report of decyl gallate and 4-ethoxycoumarin from marine seagrass Posidonia oceanica collected from Benghazi beach Libya

The goal of this research is to examine the chemical composition of the plant and identify the phytochemical constituents of the endemic seagrass species in the Mediterranean Sea, Posidonia oceanica, which has historically been used for a variety of purposes. After doing chemical screening, the existence of triterpenoid and phenolic proteins was discovered. Using preparative thin-layer chromatography and flash column chromatography techniques, seven phenolic compounds were isolated from the methanolic extracts of several plant parts. Namely decyl gallate, sinapinic acid, alpha-methyl cinnamic acid, acetosyringone, and chlorogenic acid from leaves, 4-ethoxycoumarin from rhizomes, and syringic acid from roots. The structures of these compounds were elucidated using spectroscopic methods such as ‘H and 13C-NMR. The spectra were analyzed and visualized using Mnova software and compared with standard spectra from the Willy spectra database, biological magnetic resonance data bank, and chemical book. This is the first report of decyl gallate and 4-ethoxycoumarin from the plant. This study contributes to the understanding of the phytochemical profile of Posidonia oceanica and provides valuable insights into its potential applications in various fields, including medicine, agriculture, and industry.

Development of Wound Gauze from Hylocereus undatus Dragon Fruit (Pigment) Peel Extract

The dragon fruit peels (Hylocereus undatus) are typically thrown away as agricultural waste. The disposal of bio-wastes, like peels from dragon fruit and microbiological contamination during their mass breakdown, all contribute to environmental degradation. Peel can be used to extract naturally occurring colour for pigments. The objective of this study is to investigate the feasibility of using the peel of Hylocereus undatus as a coating material for wound healing. The extraction method and potential uses of the pigments derived from the peel will be explored. The study aimed to determine the phytochemical components of Hylocereus undatus (peel) extract and the peel can be utilized as a raw material for pigment extraction due to the betalain content. With the use of a magnetic stirrer extraction, the peel of Hylocereus undatus was extracted with aqueous extraction. Thin layer chromatographic techniques are used to identify the pigment components. In the present study, we recorded both UV-VIS and FT-IR profile of peel extract to known the various phytoconstituents and determine the functional group present in Hylocereus undatus (white dragon fruit). The pigment needs to be applied to the wound gauze, and the stain resistance should be evaluated by determining how well the wound gauze can withstand contamination from the outside coating. Furthermore, the pharmaceutical and nutraceutical sectors are interested in Hylocereus undatus peel due to its components, which may have potential health applications such as anti-inflammatory, antioxidant, antibacterial, and anti-cancer characteristics

Health and Environmental Impact of Xenobiotics in Water Quality Evaluation: A Review

Study’s Novelty/Excerpt This review presents a comprehensive categorization and impact analysis of xenobiotics on humans, animals, and the environment, providing a novel synthesis of current knowledge in this field. It details the diverse sources of xenobiotics, such as microplastics and pesticides, and their pervasive presence in various environmental compartments, highlighting the significant issue of surface runoff contributing to pesticide residue in surface waters. Additionally, the review innovatively integrates a discussion on advanced detection and removal techniques, including cutting-edge chromatographic methods and bioremediation strategies, offering a holistic approach to understanding and managing xenobiotic pollutants. Full Abstract Xenobiotics are compounds or chemicals to which an organism is exposed, usually in large concentrations that are inessential to the regular pattern of metabolism of that organism. This review emphasised the categorization and impact of xenobiotics on people, animals, and the environment. It also gave a general overview of the process of discharging and detecting xenobiotics and their potential environmental fates. A chart of xenobiotic categories was also provided, including industrial products, insecticides, pharmaceuticals, personal care items, and radioactive waste. Microplastics and pesticides were discussed as xenobiotic chemicals commonly found in freshwater bodies; similarly, the impact of creating substances such as personal care products, medicinal chemicals, and insecticides through technology was discussed as the source of xenobiotics. Additionally, a thorough description of how pesticide pollution affects common environmental compartments such as soils, streambed sediment, groundwater, and surface water is provided since surface runoff accounts for more than 10% of pesticide residue in surface rivers. Effective techniques, including Fourier Transform Infrared (FTIR), High-Performance Liquid Chromatography (HPLC), Ultra-Performance Liquid Chromatography (UPLC), Gas Chromatography-Mass Spectrometry GC/MS, and Atomic Absorption Spectroscopy (AAS) along with diverse chromatographic techniques were also discussed as techniques for the analysis of xenobiotics. These techniques are often paired with state-of-the-art detection techniques like high-resolution mass spectrometry (HRMS). Highlighted as well were techniques for the removal of xenobiotics using membrane processes, improved oxidation processes, engineered wetlands, photocatalytic degradation, biotransformation, bioremediation, photo-remediation, adsorption, and bioremediation to decrease the side effects.

Pharmacological, Phytochemical and Computational Studies on Prenylated Flavonoids and Pterocarpans From Erythrina Fusca Lour.

In the present study, the dry powdered bark of Erythrina fusca was extracted with methanol. It was subjected to peripheral analgesic study using the acetic acid-induced writhing test in mice model and it demonstrated significant analgesic activity. The methanol extract was partitioned into n-hexane, chloroform and water-soluble fractions. Primarily, the chloroform fraction of the methanol extract was subjected to various chromatographic techniques and four major metabolites, Lupinifolin (1), Lupinifolin-4’-methyl ether (2), Sandwicensin (3) and Licoagrocarpin (4) were purified. Molecular docking studies of 1-4 against cyclooxygenase-2 (COX-2) enzyme suggest that they may interact with COX-2 at different levels. The pharmacokinetic and biological parameters of 1-4 were also checked through in silico tool to understand their drug-likeliness. Bangladesh J. Bot. 53(2): 305-311, 2024 (June)

In vitro and in silico assessment of antidiabetic and antioxidant potencies of secondary metabolites from Gymnema sylvestre

This study investigated the chemical constituents, antioxidant potential, and in vitro and in silico antidiabetic activity of Gymnema sylvestre. Column chromatography and spectroscopic techniques identified twelve compounds from the methanol extract, including 4 sterols (1–4), 5 triterpenoids (5–9), and 3 flavonoids (10–12). The chemophenetic significance of all compounds was also investigated. The antioxidant capacity of the extract and compounds (1–4) was evaluated using FRAP and DPPH assays. The extract exhibited strong free radical scavenging activity (IC50 = 48.34 µg/mL), while compounds (1–4) displayed varying degrees of efficacy (IC50 = 98.30–286.13 µg/mL). The FRAP assay indicated significant reducing power for both extract and compounds (58.54, 47.61, 56.61, and 49.11 mg Eq.VitC/g for extract and compounds 1 &2, 3, and 4, respectively). The antidiabetic potential was assessed through α-amylase and α-glucosidase enzyme inhibition assays. The crude extract demonstrated the most potent inhibition (IC50 = 218.46 and 57.42 µg/mL for α-glucosidase and α-amylase respectively) suggesting its potential for managing postprandial hyperglycaemia. In silico studies employed molecular docking and dynamics simulations to elucidate the interactions between identified compounds and α-amylase/α-glucosidase enzymes. The results revealed promising binding affinities between the compounds and target enzymes, with compound 6 demonstrating the highest predicted inhibitory activity with −10 kcal/mol and −9.1 kcal/mol for α-amylase and α-glucosidase, respectively. This study highlights the presence of diverse bioactive compounds in Gymnema sylvestre. The extract exhibits antioxidant properties and inhibits carbohydrate-digesting enzymes, suggesting its potential as a complementary therapeutic approach for managing hyperglycaemia associated with type 2 diabetes.

Measurement of volatile organic compounds using tethered balloons in a polluted industrial site in Catalonia (Spain).

Understanding the chemical composition of volatile organic compounds (VOCs) near emission sources and in the background atmosphere above the mixing layer height (MLH) provides insight into the fate of VOCs and is essential for developing effective air pollution control strategies. Unfortunately, knowledge of the qualitative and quantitative changes of VOCs and their vertical transport in the atmosphere is limited due to challenging experimental setups. In this study, an innovative method using tethered balloons was tested and implemented to sample 40 VOCs and O3 below and above the MLH at an industrial site in Spain. VOC and O3 samples were collected with different types of sorbent cartridges and analyzed using chromatographic techniques. Overall, a decrease in VOC concentration with altitude was observed along with a homogeneous chemical composition up to 300 m AGL. This decrease with altitude denoted the primary origin of these VOCs, which were strongly influenced by industrial processes and the traffic emissions in the area. Conversely, O3 concentrations were notably higher at balloon level and increased during nighttime temperature inversion episodes in those samples collected above the mixing layer. Ground samples contained freshly emitted pollutants of industrial origin, while balloon samples consisted of aged pollutants from traffic, other combustion sources, or from a secondary origin. This study is the first to assess the vertical composition of VOCs at a site of these characteristics and demonstrates that tethered balloons are a cost-effective method for studying air pollution dynamics from the ground to higher altitudes in the low troposphere.

Groundwater Contamination by Gas Stations in Two Eastern Amazonian Towns (Northern Brazil)

The present study analyzed the presence of the principal volatile compounds of the BTEX type (benzene, toluene, ethylbenzene, and xylene [o-, m- and p-xylene]) in samples of water from wells located at residences and gas stations in two Amazonian towns—Tracuateua and Augusto Corrêa—in the Amazon region of northern Brazil. This innovative study is extremely relevant to the Amazonian towns surveyed, given that they lack systematic policies for the environmental control of gas stations and any municipal regulations on the quality of water destined for human consumption. A combination of mass spectrometry (MS) and gas chromatography (CG) techniques was applied to analyze these contaminants in 150 samples of local groundwater collected between 2020 and 2024. One of the four BTEX compounds (toluene) was identified in seven of the samples collected (4.66% of the total) at concentrations of 0.14–2.10 µg L−1. The concentrations of contaminants were low, in general. None of the water samples analyzed here presented any critical loss of water quality for human consumption according to the Brazilian legislation concerning BTEX concentrations. Neither of the two towns surveyed in the present study has remediation programs for environmental contamination. The GC-MS approach produced satisfactory results for the assessment of the contamination of underground water reserves by gas stations in both study towns. Further research (e.g., geophysical methods) will be necessary to determine the source of the contamination and its connection with the levels of toluene identified in the underground water sampled in these Amazonian towns.

Hyphenation of supercritical fluid chromatography and trapped ion mobility-mass spectrometry for quantitative lipidomics

BackgroundLipidomics studies require rapid separations with accurate and reliable quantification results to further elucidate the role of lipids in biological processes and their biological functions. Supercritical fluid chromatography (SFC), in particular, can provide this rapid and high-resolution separation. The combination with trapped ion mobility spectrometry (TIMS) has not yet been applied, although the post-ionization separation method in combination with liquid chromatography or imaging techniques has already proven itself in resolving isomeric and isobaric lipids and preventing false identifications. However, a multidimensional separation method should not only allow confident identification but also provide quantitative results to substantiate studies with absolute concentrations. ResultsA SFC method was developed and the hyphenation of SFC and TIMS was further explored towards the separation of different isobaric overlaps. Furthermore, lipid identification was performed using mass spectrometry (MS) and parallel accumulation serial fragmentation (PASEF) MS/MS experiments in addition to retention time and collision cross section (CCS). Quantification was further investigated with short TIMS ramps and performed based on the ion mobility signal of lipids, since TIMS increases the sensitivity by noise filtering. The final method was, as an exemplary study, applied to investigate the function of different ceramide synthases (CerS) in the nematode and model organism Caenorhabditis elegans (C. elegans). Loss of three known CerS hyl-1, hyl-2 and lagr-1 demonstrated different influences on and alterations in the sphingolipidome. SignificanceThis method describes for the first time the combination of SFC and TIMS-MS/MS, which enables a fast and sensitive quantification of lipids. The results of the application to C. elegans samples prove the functionality of the method and support research on the metabolism of sphingolipids in nematodes.

Evaluation of Antiviral, Antibacterial and Antioxidant Activity of Morinda tinctoria Roxb., Abroma augusta L. Educes and Myristica fragrans Houtt. Ethereal Oil in Microcapsules

Viruses and bacteria can interfere with human functioning; scientists are always looking for new ways to harness the healing power of plants. There is potential for a new type of medicine to be developed from plant materials rich in biologically active chemicals. The purpose of this research was to create microcapsules and scrutinize the biological outcomes of a variation of plant educes and ethereal oils. Using chromatographic techniques, we identified the primary components of the educe and ethereal oil, measured the antioxidant activity spectrophotometrically, tracked the development of 09 different infectious agents, and calculated the antiviral result on coronavirus-contaminated avian cells. The extract of Abroma augusta L. demonstrated the highest levels of antioxidant and antiviral activity (27.28 – 0.32 and 642.54 – 9.12 g TE/g dw via DPPH and ABTS techniques, correspondingly). The FRAP assay found that Morinda tinctoria Roxb. extract had the highest antioxidant activity (685.72 – 4.65 mg FS/g dw) and showed antibacterial activity against gram-positive pathogens. Excipients and their quantities were crucial to the emulsion’s consistency. The diameter of the enlarged microcapsules containing educes and ethereal oil was greater than twice in intestinal media and less than half that in gastric media, with a starting diameter of 1.86 mm.

RP-HPLC Method for Estimation of Caspofungin in Bulk and in Parenteral Dosage Form

In order to more precisely and accurately estimate the antifungal medicine caspofungin and its parenteral dosage form, a new, straightforward, and cost-effective reverse-phase high-performance liquid chromatography (RP-HPLC) technique has been created. The accuracy, precision, linearity, specificity, and reproducibility of the method for the measurement of caspofungin in used equipment were determined during the present study’s validation according to the International Council of Harmonization (ICH) criteria. Elution was accomplished using a CHEMSIL ODS-C18 (5μm) column in isocratic mode with a mobile phase consisting of acetonitrile:ammonium acetate buffer at pH 4.8 (60:40%v/v). The mobile phase was pumped into the column at a flow rate of 1.0 mL/min, and the eluent was detected using a variable wavelength UV detector set at 210 nm. The column dimensions are 250 × 4.6 mm. The chromatogram for the optimized RP-HPLC method of caspofungin estimation had 28,99 theoretical plates (N) and a strong peak at a resolution time of 16,105 minutes. The thorough validation process led to the conclusion that the approach is stable and could be applied for the duration of the drug’s shelf life.

Investigation of the uterine modulating activities and mechanisms of Brachystegia eurycoma Harms (Leguminosae) methanol stem bark extract and fractions

Dysfunctional labour (DL) is a major cause of maternal and neonatal deaths worldwide. The only clinically available drug is oxytocin which is about 50% effective. Therefore, the development of new effective drugs for DL is a necessity. The medicinal plant Brachystegia eurycoma Harms (synonym B. spiceaformis) is used for labour management in ethnomedicine. In the search for new lead compounds for DL therapy, the stem bark of B. eurycoma was subjected to bioactivity-guided fractionation procedures to elucidate its uterine-modulating activities and active compounds. B. eurycoma stem bark extract (BE) was fractionated via vacuum liquid chromatographic techniques. The fractionation process was guided by ex vivo uterine contractility assays on the mouse uterus, performed using spontaneous, oxytocin, and high KCl-induced contractility assays. Furthermore, the characterization of the chemical constituents was performed using nuclear magnetic resonance (NMR) and mass spectrometry (MS). BE produced dual effects on uterine contractility which was dependent on the reconstitution period. The freshly prepared crude extract (BEF) inhibited uterine contractility (IC50 amplitude = 0.8 ± 0.1 mg/ml; IC50 frequency = 1.4 ± 0.2 mg/ml). However, contractility was augmented when the reconstituted extract was stored for 24 h and beyond (BES) (EC50 amplitude = 0.2 ± 1.2 mg/ml; EC50 frequency = 0.91 ± 1.2 mg/ml). In addition, the compounds caffeine, genistein, and prunetin were identified from the potent BE fractions via the different spectroscopic and spectrometric tools. This study demonstrated a storage-dependent dual effect of BE where BEF induced inhibition and BES augmented uterine contractility. Findings from this study also suggest that caffeine and phytoestrogens contributed to the uterine-modulating activities of BE. Thus, further investigation of these compounds in combination and as separate lead compounds is required for DL therapeutic management.

Twin Strep-Tag Modified CPT1A Mitochondrial Membrane Chromatography in Screening Lipid Metabolism Regulators.

Mitochondrial Membrane Chromatography (MMC) is a bioaffinity chromatography technique developed to study the interaction between target proteins embedded in the mitochondrial membrane and their ligand compounds. However, the MMC stationary phases (MMSP) prepared by chemical immobilization are prone to nonspecific binding in candidate agent screening inevitably. To address these challenges, Twin Strep-Tag/Strep Tactin was employed to establish a specific affinity system in the present study. We prepared a carnitine palmitoyltransferase 1A (CPT1A) MMSP by specifically linking Strep-tactin-modified silica gel with the Twin Strep-Tag on the CPT1A-oriented mitochondrial membrane. This Twin Strep-Tag/Strep Tactin modified CPT1A/MMC method exhibited remarkably better retention behavior, longer stationary phase lifespan, and higher screening specificity compared with previous MMC systems with glutaraldehyde immobilization. We adopted the CPT1A-specific MMC system in screening CPT1A ligands from traditional Chinese medicines, and successfully identified novel candidate ligands: ononin, isoliquiritigenin, and aloe-emodin, from Glycyrrhiza uralensis Fisch and Senna tora (L.) Roxb extracts. Biological assessments illustrated that the compounds screened promote CPT1A enzyme activity without affecting CPT1A protein expression, as well as effectively reduce the lipid droplets and triglyceride levels in the high fat induction HepG2 cells. The results suggest that we have developed an MMC system, which is promising for studying the bioaffinity of mitochondrial membrane proteins to candidate compounds. This system provides a platform for a key step in mitochondrial medicine discovery, especially for bioactive molecule screening from complex herbal extracts.

Catalyst- and chromatography-free multi-component domino synthesis of 5-alkyl barbituric acids at room temperature

5-Alkylated barbituric acids are an important class of compounds that constitute the basic moiety of several clinically used hypnotic drugs. Here we report a catalyst-free domino Knoevenagel-Michael addition involving barbituric acid, aldehyde, and N,N-disubstituted aniline in solvent acetonitrile to synthesize 5-alkylated barbituric acid derivatives (72–94% yield) without using any chromatographic separation techniques. The C-4 position of aniline acts as the Michael donor. All the reactions are successfully performed without catalysts, providing an environment-friendly and economical route for the synthesis. Moreover, catalyst-free reactions are less sensitive to air and moisture unlike many metal catalysts, with easy separation of products, and simple operating procedures as there is no need for catalyst weighing, recovery, and removal. A plausible mechanism is also proposed based on control experiments.

Development and validation of colorimetric-assisted chemometrics methods based on the localized gold nanoparticles surface plasmon resonance for fast simultaneous estimation of anti-hepatitis C virus drugs in their combined dosage form: A comparative study with HPLC method

The present work describes a developed analytical method based on a colorimetric assay using gold nanoparticles (AuNPs) along with chemometric techniques for the simultaneous estimation of sofosbuvir (SOF) and ledipasvir (LED) in their synthetic mixtures and tablet dosage form. The applied chemometric approaches were continuous wavelet transform (CWT) and least squares support vector machine (LS-SVM). Characterization of AuNPs and AuNPs in combination with the drug was performed by UV–vis spectrophotometer, transmission electron microscopy (TEM), dynamic light scattering (DLS), and Fourier transform infrared (FTIR) spectroscopy. In the CWT method, the zero amplitudes were determined at 427 nm with Daubechies wavelet family for SOF (zero crossing point of LED) and 440 nm with Symlet wavelet family for LED (zero crossing point of SOF) over the concentration range of 7.5–90.0 μg/L and 40.0–100.0 μg/L with coefficients of determination (R2) of 0.9974 and 0.9907 for SOF and LED, respectively. The limit of detection (LOD) and limit of quantification (LOQ) of this method were found to be 7.92, 9.96 μg/L and 12.02, 30.2 μg/L for SOF and LED, respectively. In the LS-SVM model, the mean percentage recovery of SOF and LED in synthetic mixtures was 98.29 % and 99.25 % with root mean square error of 2.392 and 1.034, which were obtained by the optimization of regularization parameter (γ) and width of the function (σ) based on the cross-validation method. The proposed methods were also applied for the determination concentration of SOF and LED in the combined dosage form, recoveries were higher than 95 %, and relative standard deviation (RSD) values were lower than 0.4 %. The achieved results were statistically compared with those obtained from the high-performance liquid chromatography (HPLC) technique for the concurrent estimation of components through one-way analysis of variance (ANOVA), and no significant difference was found between the suggested approaches and the reference one. According to these results, simplicity, high speed, lack of time-consuming process, and cost savings are considerable benefits of colorimetry along with chemometrics methods compared to other ways.