BMC Chemistry最新文献

Shilajit, a natural substance used in traditional and modern medicine, has gained prominence as a vital component in dietary supplements. Concerns regarding its use in complementary medicine have arisen due to limited information regarding its composition. Considering thallium’s well-known toxicity, this study employs flow - injection differential-pulse anodic stripping voltammetry to accurately quantify thallium in natural Shilajit and Shilajit-based commercial supplements from various regions. The limit of detection and limit of quantification were determined as 6.58 × 10^− 3 µg.mL^− 1 and 1.98 × 10^− 2 µg.mL^− 1, respectively. Thallium contents were detected up to 0.226 µg.g^− 1 in natural Shilajit, but mainly in the range of a few tenths of µg.g^− 1. Thallium contents were found up to 0.5 µg.g^− 1 in the supplements studied. Consumption of one pill of supplement, introduces up to 0.095 µg of Tl to the body. Notably, the concentration of thallium in some supplements was higher than in crude Shilajit, raising concerns about the potential health risks associated with long-term consumption. This study underscores potential health risks associated with thallium in both Shilajit and supplements. Regular monitoring and standardized testing are essential to ensure compliance with safe thallium limits, protecting consumers against potential thallium poisoning.

White and Green Analytical Chemistry are innovative approaches in analytical chemistry that prioritize both sustainability and efficiency. Together, these approaches aim to advance scientific research while minimizing environmental impact and enhancing safety. This integration of environmental consciousness into analytical practices represents a significant step forward in achieving sustainable scientific progress. In the present study, a sensitive eco-friendly HPLC-DAD method was carried out and validated to allow concurrent determination of Donepezil HCl (DPZ) and Curcumin (CUR) in their pure form and laboratory made nano-liposome formulation. Optimum seperation was accomplished by utilising Zobrax Eclipse Plus C18 column (4.6*100 mm,5 μm) with gradient elution of the mobile phase composed of 0.02 M phosphate buffer at pH 3.2 and ethanol at flow rate of 1.5 ml/min. A diode array detector (DAD) was implemented for detection at 273 nm and 435 nm for DPZ and CUR, respectively, with the column oven set at 40 °C. The method was validated according to ICH specifications in terms of accuracy, precision, linearity range, detection and quantification limit. The calibration plots were linear with correlation coefficients (r2) = 0.999 over the range (0.1–100 µg/ml) and (0.1–100 µg/ml) for DPZ and CUR, successively. The validated HPLC-DAD approach was adopted to analyse both medications in laboratory prepared nano-liposomal formulation in which the analytes were successfully quantified with good recovery values and no disrubtion from the added excipients. The investigation of whiteness, blueness, and greenness metrics revealed a major benefit of the suggested approach over previous reported ones.

Malaria is the extensive health concern in sub-Saharan Africa, with Plasmodium falciparum being the most lethal strain. The continued emergence of drug-resistant P. falciparum advocates for the development of new antimalarials. Our current study aimed to effectively explore the interaction capabilities of iso-mukaadial acetate (IMA) and betulinic acid (BA) against two essential P. falciparum glycolytic pathway proteins, PfLDH and PfHk. Recombinant PfLDH and PfHk were independently expressed in E. coli BL21 (DE3) cells and subsequently purified using affinity chromatography. Protein–ligand interaction studies probed in silico and in vitro approaches. Parasite inhibition studies confirmed potent antimalarial activity against the P. falciparum NF54 strains, with BA and IMA showing IC₅₀ values of 1.27 µg/ml and 1.03 µg/ml against the asexual stage of P. falciparum, respectively. FTIR experiments confirmed interactions between the compounds and the secondary structure of the proteins. Direct protein–ligand interaction studies analysis using microscale thermophoresis (MST) showed a K_D value of 0.1036 ± 0.6001 µM for the PfLDH-BA complex and 0.7473 ± 0.3554 µM K_D value for PfLDH-IMA. Meanwhile, PfHk-IMA had 0.39701 ± 0.16298 µM K_D value, while the PfHk-BA complex had no interaction detected. Molecular docking and molecular dynamics simulation studies were used to measure and confirm the interactive strength of complexes. Molecular docking reported a binding score of − 1.155 kcal/mol for the PfLDH-BA complex and a binding score of − 3.200 kcal/mol for PfLDH-IMA. The PfHk-BA complex had − 2.871 kcal/mol and PfHk-IMA complex had − 4.225 kcal/mol binding score. In conclusion, BA and IMA compounds had better interactions and remained bound within the binding sites of the glycolytic pathway proteins (PfLDH and PfHk).

Background

As the common antibacterial drugs in folic acid oral liquid, parabens are listed as mandatory substances in the quality standard. Both the Chinese Pharmacopoeia and the United States Pharmacopoeia use high performance liquid chromatography for the determination of folic acid, but the quantitative methods of parabens are different. Pharmacopoeias use different instruments to quantify folic acid and parabens, resulting in cumbersome and cumbersome detection methods.

Objective

Without changing the type of instrument and mobile phase, two methods were established for the determination of folic acid and parabens (methyl paraben; ethyl paraben; propyl paraben) using respective wavelengths and flow comparisons Propyl benzoate) high performance liquid chromatography method.

Method

Chromatographic separation was achieved on an Agilent 5 TC-C₁₈ HPLC column (5 μm; 250 μm × 4.6 mm) maintained at 25 °C (column temperature). The mobile phase consisted of phosphate buffer (pH 4.0)-methanol. When the ratio is 99:1, it is used to determine the content of folic acid, and when the ratio is 79:21, it is used to determine the content of antimicrobial agents. The flow rate used was 1.2 mL/min, the injection volume of folic acid was 20 µL, and the injection volume of bacteriostatic agent was 50 µL. In addition, the blue applicability grade index (BAGI) and analytical greenness (AGREE) metric tools were used to evaluate the greenness and environmental friendliness of the developed methods.

Results

The method has a good linear relationship with R² ≥ 0.9995, the average recovery rate of the two methods is ≥ 95%, and the relative standard deviation (RSD%) accuracy is less than 0.21%. The BAGI tool characterizes the developed method as green. The AGREE score is around 0.5, and the method is also largely consistent with the principles of green analytical chemistry.

Conclusions

The HPLC method was established for the rapid determination of folic acid and antibacterial agent of parabens in folic acid. The method has high accuracy, strong specificity, high recovery rate, good stability and environmental friendliness. Compared with the method in the pharmacopoeia, it has strong resistance to complex matrix interference, greatly shortens the detection time, and has little damage to the instrument and chromatographic column. It can be used for the quality standard of folic acid oral liquid.

Lidocaine poses challenges when it comes to direct spectrophotometric measurement due to the lack of sharp peak within its spectra in zero-order. This lack of a distinct peak makes it difficult to accurately quantify lidocaine using traditional direct spectrophotometric methods. In our study, different univariate and multivariate spectrophotometric techniques have been established and their validity has been assessed for the determination of the mixture of Lidocaine HCl (LD), Oxytetracycline HCl (OTC) together with LD carcinogenic impurity [2,6- dimethylaniline] DMA. LD was resolved from the other two components using ratio difference and derivative ratio methods. OTC was determined in zero- order at 360 nm and by using constant value and concentration value methods, while DMA was determined by using constant multiplication at 237 nm as well as by using constant value and concentration value methods after elimination of OTC by ratio subtraction technique. Moreover, Partial Least Squares and Principal Component Regression multivariate approaches were applied to quantify and evaluate the mixture. The developed methods underwent validation following International Council for Harmonization guidelines. The validation process demonstrated that all suggested methods are accurate and selective in their measurements. Additionally, statistical analysis was conducted to compare the developed and reported methods. Furthermore, one-way analysis of variance was performed to compare both proposed and reported spectrophotometric methods.

A simple, rapid, and reproducible high-performance liquid chromatography (HPLC) method has been developed and validated for the determination of β-sitosterol in the pharmaceutical dosage form of moist exposed burn ointment (MEBO). This method involved an effective sample procedure for extraction of β-sitosterol from MEBO using an alkali saponification agent composed of 0.8 N ethanolic NaOH and diethyl ether. The chromatographic separation was achieved on a C18 column (50 × 3.0 mm, 2.5 μm), using a mobile phase composed of methanol and acetonitrile (70:30 v/v) pumped in an isocratic mode at a flow rate of 0.7 mL/min. The column temperature was maintained at 40 °C, the injection volume was 10 µL, and the detection wavelength was 203 nm. Employing these conditions, the retention time was found to be 2.10 min. The developed method was validated for its specificity, linearity, accuracy, precision, the limit of detection, the limit of quantification, robustness, and solution stability based on International Council for Harmonisation (ICH) guidelines Q2 (R1). Our proposed method demonstrated superior performance compared to other reported methods. It exhibited a linearity range of 30 to 500 µg/mL and improved detectability with a limit of detection (LOD) of 4.65 µg/mL, highlighting its high sensitivity. Additionally, the separation was achieved in a remarkably short analysis time of just 2.1 min, which not only enhanced throughput but also significantly minimized waste and solvent consumption, thereby making it a more sustainable and effective alternative for β-sitosterol extraction. Moreover, in the light of green and white analytical chemistry, a comprehensive ecological and sustainable tri-color coded assessment protocol was established. The proposed method has been successfully applied to quantify β-sitosterol in commercial products (MEBO^®, Avomeb^® and BISTROl^®) demonstrating its suitability for routine quality control analysis of β-sitosterol in pharmaceutical ointment dosage forms.

Ethers are high value organic compounds widely applied in chemical industry, natural products, material, pharmaceuticals, argochemicals, as well as modern organic synthesis. Herein, we report an adaptive TFA-catalyzed cross-coupling of alcohols with various oxygen nucleophiles (nitro-, halogen-, sulfur-, nitrogen-, aryl-, and alkynyl-substituted aliphatic alcohols), delivering diverse unsymmetrical ethers under mild conditions and simple operation. This protocol features a broad range of substrate scope and high catalytic efficiency (54 examples, up to 99% yield). The decagram scale performance and one-step synthesis of drug molecules evidenced the potential industrial production and practicability of this protocol.

Graphical Abstract

Surfactant-modified biochar is a viable adsorbent for eliminating Cr(VI) from synthetic wastewater. The biochar obtained from the zea mays plant (BC) was tailored with sodium dodecyl sulfate (SDS) as an anionic surfactant forming SDS-BC adsorbent. Different controlling conditions have been evaluated including pH of the solution, biomass concentration, primary Cr(VI) concentration, time of adsorption, and temperature. Under the best controlling circumstances, the percentage of removal has attained 99%. The pseudo-second-order kinetic model best described the removal process, according to the kinetic data, while the Temkin model, one of the applicable adsorption isotherm models, well expressed the adsorption process. The thermodynamic parameters were computed, which disclosed the spontaneity and exothermic character of the Cr(VI) elimination. According to the regeneration cycles, SDS-BC was cost-effective and had a good removal capability.

Graphical Abstract

In this work, selenium (IV) ions were adsorbed from aqueous solutions by the strongly basic anion exchange resin Amberlite IRA-400. The morphology of the resin before and after Se(IV) sorption was investigated using different techniques such as energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). To determine the ideal sorption conditions, a batch approach was used to examine the variables affecting Se(IV) sorption performance, including pH, shaking time, adsorbent dosage, initial metal ion concentration, and temperature. The results showed the optimal parameters for the highest percentage of selenium (80.25%) at an initial concentration of 100.0 mg L⁻¹, pH 3.0, the adsorbent dosage of 10.0 mg, and the shaking time of 60.0 min. According to the experimental findings, the sorption process was satisfactorily explained by the pseudo-second-order kinetic model. The maximum adsorption capacity at pH 3.0 was 18.52 mg g⁻¹, and the adsorption rather well followed the Langmuir adsorption isotherm. Moreover, exothermic and spontaneous sorption reaction was the result of thermodynamic properties (negativity of both ΔG° and ΔH°). The adsorption phase's random distribution of the resin-solution interface is indicated by the positive value of ΔS^o. Finally, the desorption study was performed using different concentrations of desorbing agents; HNO₃, HCl, and sodium acetate. The results illustrated that the effective desorbing agent was 1.0 mol L^-1 HNO₃, with desorption efficiency reaching about 96.4%. Finally, the Amberlite IRA-400 demonstrated excellent adsorption–desorption behavior over five times, suggesting that the Amberlite IRA-400 could be an effective candidate for the sorption of Se(IV) from several metal ions that occur in fission products.