Current Analytical Chemistry - Volume 20, Issue 8, 2024

Aims: Applicability of QbD-assisted analytical method for simultaneous detection of tetrahydrocurcumin and folic acid in developed nanostructured lipid carriers. Background: Diabetic foot ulcer (DFU) is a multifactorial disorder that involves chronic inflammation, oxidative stress and neuropathy. Current treatment therapies involving the use of growth factors and skin substitutes being costly, are out of reach for the majority of patients. The present research explored the usefulness of a combination of tetrahydrocurcumin and folic acid-loaded nanostructured lipidic carriers in DFU. Objectives: To develop and validate a QbD-assisted method for simultaneous analysis of tetrahydrocurcumin (THC) and folic acid (FA). Applicability of the above method to determine total drug content (TDC) and entrapment efficiency (EE) of nanostructured lipid carriers (NLCs) loaded with THC and FA. Methods: A high-performance liquid chromatographic (HPLC) method was developed, optimized and validated using Box-Behnken design for improved method performance. Chromatographic separation was conducted on a Supelco 250 x 4.6 mm (5 μm) column with optimized mobile phase composition containing tetrahydrofuran: citric acid buffer pH 3.5 (50:50) at a flow rate of 0.4 mL.min-1 and diode array detection between 210 and 360 nm. Results: The method developed in a concentration range of 1 to 100 μg.mL^-1 was found to be linear (R² 0.999, p≤0.001), accurate (99.10-101.70%) and precise with high recovery values in intra and inter-day results. The system adaptability and robustness evaluation revealed that the percent recovery ranged from 96.90 to 102.80%, and the percent relative standard deviation (%RSD) values were less than 2%. Moreover, the method was further applied for the determination of TDC (86±6% and 96±8%) and drug EE (81±21% and 73±13%) for THC and FA, respectively. Conclusion: The investigation indicated the applicability of the developed and validated method for the estimation of THC and FA in the developed nanostructured lipidic carriers.

Background: The zero-field splitting parameters of Mn²⁺gt; doped L-histidine-4- nitrophenolate 4-nitrophenol single crystals are evaluated. Methods: The superposition model and perturbation theory are used to obtain zero-field splitting parameters for Mn²⁺ ion-doped LHPP single crystals. The optical spectra of the system are computed using the crystal field parameters from the superposition model as input into the crystal field analysis program. Results: The evaluated zero field splitting parameters are in good match with the experimental values when local distortion is taken into account. The experimental finding that the Mn²⁺ ion enters the L-histidine-4-nitrophenolate 4-nitrophenol lattice at the interstitial position is supported by the theoretical result. Conclusion: It is found that the calculated and experimental band positions agree fairly well. Thus, the theoretical study supports the experimental observation.

Background: Polystyrene nanospheres are used as a substrate for the hydrothermal coating of tungsten trioxide (WO3 ) to form a core-shell composite of PS@WO3 . The core-shell structure is used for the next sintering step. This produces porous WO3 . The focus of this study is on the role of porous WO3 in enhancing photocatalytic performance. Methods: The hydrothermal method was employed for coating, and the surface morphology, as well as the structural properties of WO3 -coated PS spheres, were systematically investigated using SEM and XRD analyses. Additionally, the sintering process was introduced to enhance the material by inducing rupture in the PS sphere core, creating voids that significantly increased the material's surface area. Results: The evaluation of the effect of sintering temperature on photodegradation efficiency highlighted the crucial role of sintering temperature. Un-sintered and 300°C sintered WO3 , both having a hexagonal crystalline structure, exhibited superior degradation efficiencies compared to samples sintered at higher temperatures (400°C and 500°C). In particular, the 300°C sintered WO3 outperformed its un-sintered counterpart despite identical crystalline structures. The performance of the PS@WO3 composite was assessed to determine the enhanced role of porous WO3 . The porous WO3 obtained, in particular by the sintering of the core-shell PS@WO3 composites at 300°C, showed a remarkable improvement in the degradation efficiency. These composite demonstrated over 95% efficiency within 10 minutes and achieved near complete (100%) degradation for a further 10 minutes, surpassing the performance of pure WO3 . It is important to clarify that while the final product was predominantly WO3 after the sintering process, the inclusion of PS served a critical purpose in creating voids during sintering. The PS@WO3 composite structure used as a resource for the preparation of porous WO3 , even with a potentially reduced PS composition, has been found to play a significant role in influencing the surface area of the material, and consequently the photocatalytic performance. Conclusion: The study has highlighted the importance of crystalline structure and sintering conditions in optimizing the efficiency of photocatalytic materials. The porous WO3 obtained, in particular by the sintering of the core-shell PS@WO3 composites at 300°C, showed promising potential for applications under UV and visible LED light irradiation. These results provide valuable insights for the development of advanced photocatalytic materials with improved performance, highlighting WO3 as the key contributor to the observed improvements.

gt;Introduction: In this work, a polyacrylate polymer was synthesized into a pipette tip containing cotton fibers and used to extract carvedilol from water and urine samples. Methods: A high-performance liquid chromatography-ultraviolet detection method was developed, which demonstrated the suitability of the purposed pipette tip micro-solid-phase extraction device. Factors affecting the fabrication procedure and polymer quality were studied and optimized. In the next step, the sample preparation process (including extraction and desorption) was fully optimized, and the optimized method was validated. Results: A coating with suitable mechanical and chemical stability was achieved. Its structure was successfully characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Within-batch and between-batch fabrication reproducibility were obtained at 3.0 and 9.0%, respectively. The developed method displayed a limit of detection of 1.1 μg L^-1 when 1.5 mL of sample was processed, and it was linear in the concentration range of 3.3-350 μg L^-1 with LLOQ of 5 μg L^-1. The polyacrylate cotton-based pipette tip was finally used to extract carvedilol from aqueous media with acceptable recoveries of 92-106%. Conclusion: The proposed method is simple and fast and requires low sample volumes. In addition, this method has been evaluated in terms of greenness with three different tools, and the evaluation results with all three tools have shown that this method is one of the green and environmentally friendly methods.

Background: Chlorogenic acid, an ester of caffeic acid with quinic acid, also known as 5- O-caffeoylquinic acid (5-CQA), is a ubiquitous plant constituent that is an important intermediate in lignin biosynthesis. In some cases, it occurs at surprisingly high levels in the leaves and fruits of certain higher plants, such as coffee beans. Due to its catechol moiety and an extended side chain conjugation, it easily forms a resonance-stabilised phenoxy radical, accounting for its powerful antioxidant potential. Objective: The objective of this work was to determine if the esterification and methylation of 5- CQA would enhance its antioxidant activity. Methods: Two 5-CQA derivatives were prepared for this study. Chlorogenic acid was esterified with methanol over Amberlite IR120-H to obtain methyl chlorogenate, while methyl 3',4´-dimethyl chlorogenate was prepared from 5-CQA by treatment with diazomethane. Spectroscopic methods confirmed the structure of these derivatives. Their antioxidant properties were tested to establish a relationship between structure and antioxidant activity. Results: Antioxidant activity results were generated for 5-CQA and its ester analogues using eight different methods. Depending on the method applied, results were expressed as IC50/MCE50 values or as equivalents of the applied standard (ascorbic acid and Trolox). Conclusion: In most of these tests, 5-CQA showed the highest antioxidant activity compared to its derivatives. Nevertheless, due to their hydrophobic characteristics, their ester analogues remain promising antioxidant candidates in emulsifying systems.

Background: Hydrazine may induce gene abnormalities, cancer, and severe damage to the liver, lungs, kidneys, and central nervous system. Therefore, the development of reliable analytical techniques with high selectivity and sensitivity to detect hydrazine is required for the protection of human health and safety. Objectives: Traditional methods for detecting N2H4 are frequently time-consuming, less accurate, and unsuitable for the analysis of living systems. Numerous fluorescent probes for hydrazine have been produced and gained some valuable results recently. The creation of a simple fluorescent probe for hydrazine detection is the goal of this project. Method: In this study, 300 μL of probe 3-methyl-2-oxo-2H-chromen-7-yl propionate (MOCP) was mixed with an equivalent amount of the solution of each analyte to obtain the measurement solution. Following a 10-minute room temperature incubation period, the fluorescence spectra of the resultant solution were recorded. Results: The fluorescence intensity of the probe was noticeably enhanced when N2H4 was added to the probe, but almost no fluorescence enhancement was observed when other competitive ions were added. Conclusion: A hydrazine fluorescent probe based on 4-hydroxycoumarin fluorophore was developed. The probe MOCP displayed high sensitivity and selectivity for hydrazine, with a color change from colourless to blue for detection by the naked eye. Moreover, it demonstrated a low detection limit of 20 nM and a fast reaction time of 30 s.

Introduction: Camptothecin (CPT) is pivotal in cancer treatment, derived from various CPT-producing plant species, and is a fundamental component in synthesizing valuable cancer drugs like Irinotecan and Topotecan. Sourcing from nature poses conservation issues, fostering interest in the herbaceous Ophiorrhiza plant as a more sustainable alternative. Ophiorrhiza species in Sri Lanka lack comprehensive study, warranting exploration for echo-friendly anticancer compound production. Objectives: This study examines CPT and analog content in Ophiorrhiza mungos, O. pectinata, and O. rugosa across diverse Sri Lankan regions. Methods: The study employs Thin Layer Chromatography (TLC), High-Performance Liquid Chromatography- DAD (HPLC-DAD), and Liquid Chromatography-Mass Spectrometry (LC-MS) to quantify and confirm CPT and its analogs. Results: Significant variations in the content of CPT and its analogs were observed among plant parts and regions. O. mungos from Deraniyagala and Bibile regions notably exhibited elevated CPT levels in fruits and roots. O. rugosa var. Angustifolia and O. pectinata also exhibited a considerable content of CPT in their roots, though it was significantly lower (p < 0.005) than O. mungos. Conclusion: The study validates analytical methods for specificity, linearity, precision, accuracy, and sensitivity per ICH guidelines. The results indicate that Ophiorrhiza species, especially O. mungos and O. rugosa var. Angustifolia holds the potential to be a sustainable source of CPT. Optimizing cultivation practices offers an eco-friendly solution for anticancer compound production, alleviating species threats and conserving biodiversity.