Browsing by Author "Ali, H.S."

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Analytical Techniques for Methyldopa and Metabolites: A Comprehensive Review
(Taylor and Francis Ltd., 2025) Barzani, H.A.H.; Sulaiman, S.H.; Omer, R.A.; Mer, A.H.; Ali, H.S.
Methyldopa, a centrally acting α2-adrenergic agonist, remains a key antihypertensive drug, particularly prescribed for pregnant and renal-impaired patients. Its clinical significance has led to extensive research aimed at developing reliable analytical methods for its accurate, sensitive, and selective determination in pharmaceutical formulations and biological matrices. Relevant literature was retrieved from Scopus, Web of Science, ScienceDirect, PubMed, and Google Scholar, restricted to English-language publications. This review critically examines the diverse analytical approaches used for Methyldopa quantification, outlining their principles, advantages, limitations, and applicability in both advanced and resource-limited settings. Chromatographic methods, especially high-performance liquid chromatography (HPLC) and liquid chromatography–mass spectrometry (LC-MS/MS), remain the most robust techniques, offering excellent sensitivity (LOD: 10–50 ng/mL for HPLC; as low as 0.7–15 ng/mL for LC-MS/MS) with rapid analysis times. While LC-MS/MS provides superior detection, it is limited by high costs and technical expertise requirements. Electrochemical methods, particularly voltammetry, stand out for their affordability, rapid analysis, and feasibility in decentralized laboratories, achieving LOD values as low as 0.01–0.05 µM. Spectrophotometric approaches, primarily UV-Vis, remain the simplest and most cost-effective options, making them useful for routine quality control, though with reduced selectivity and higher detection limits. Key analytical challenges include Methyldopa’s low concentration in biological fluids, chemical instability, and matrix interferences. This review provides a comparative evaluation of chromatographic, spectrophotometric, and electrochemical techniques, emphasizing the need for portable, low-cost platforms to expand accessibility in therapeutic monitoring. Overall, it offers critical insights for advancing Methyldopa analysis and improving clinical management in diverse healthcare settings. © 2025 Elsevier B.V., All rights reserved.
Electroanalytical Determination of Salbutamol in Pharmaceutical Formulations Using Cathodically Pretreated Boron-Doped Diamond Electrode
(Marmara University, 2018) Talay Pınar, P.; Ali, H.S.; Abdullah, A.A.; Yardim, Y.; Şentürk, Z.
This paper examined for the first time the possibilities of the usage of the cathodically pretreated boron-doped diamond (CPT-BDD) electrode for the redox behavior of salbutamol (SAL) using cyclic and adsorptive stripping voltammetry. The cyclic voltammograms showed an irreversible and adsorption-controlled oxidation peak at about +1.0 V in the Britton-Robinson (BR) buffer (pH 9.0) solution. Under the optimized experimental condition, using square-wave adsorptive stripping mode, the compound yielded a well-defined voltammetric response in BR buffer, pH 9.0 at +0.95 V (vs. Ag/AgCl) (after 30 s accumulation at an open circuit condition). A linear calibration graph was obtained in the concentration range of 4.15 to 83 μg mL-1 (1.73x10-5-3.47x10-4 M). A detection limit of 1.21 μg mL-1 (5.06x10-6 M) was observed. The suggested method was also applied to the determination of SAL in the drug formulations. © 2018 Elsevier B.V., All rights reserved.
The Rationale for Current Pharmacotherapy of Covid-19
(Yuzuncu Yil Universitesi Tip Fakultesi, 2020) Yunusoğlu, O.; Ali, H.S.
Severe acute respiratory syndrome (SARS-CoV), Middle East respiratory syndrome (MERS) and SARS-CoV-2 are related to the coronaviridae family. The worldwide pandemic of the new coronavirus disease 2019 (COVID-19) due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) broke out in Wuhan province of China, in December 2019, and spread rapidly throughout the world. More than 6 million cases and 370,000 deaths had been reported by 31 May 2020 in more than 200 countries. No data are available from any clinical trials supporting a proposed prophylactic therapy. More than 300 active clinical trials are currently underway. Many drugs have been studied against COVID-19, but there is no actual evidence from any randomized clinical trials with a potential therapy that can improve outcomes of a patient diagnosed with COVID-19. In some cases, many of the investigated drugs cause side effects, e.g. chloroquine, ribavirin. Besides its beneficial effects such as reducing disease progression and decreasing symptom duration, chloroquine can cause cardiac side effects. Ribavirin, on the other hand, is recognized as a teratogen and considered unsafe in pregnancy. No special effective antiviral therapy against COVID-19 is currently available. Although the course of the disease is mild and moderate in the majority of the COVID-19 patients, more than 5%-7% of the patients' life being under severely susceptible threats requires more effective medicinal products, urgently. © 2020, Yuzuncu Yil Universitesi Tip Fakultesi. All rights reserved.
Utilization of a Simple and Fast Electroanalytical Method with an Unmodified Boron-Doped Diamond Electrode for Taxifolin Sensing in Food Supplement Samples
(Springer, 2025) Ali, H.S.; Barzani, H.A.H.; Yardim, Y.
Using an unmodified boron-doped diamond electrode, an electrochemical sensor was established for the determination of taxifolin through square-wave voltammetry. Cyclic voltammetry measurements conducted in a 0.1 M HClO4 solution showed that taxifolin exhibits irreversible behavior with diffusion control, marked by distinct oxidation peaks at approximately + 1.04 V (PA1) and + 1.44 V (PA2) versus Ag/AgCl. Furthermore, the pH as well as the supporting electrolyte had an effect on the oxidation process. The quantification of taxifolin was based on its two anodic peaks. The optimized method yielded a current response that was linearly proportional to taxifolin concentration, ranging from 2.5 to 50.0 μg mL−1 (8.2 × 10–6 to 1.6 × 10–4 M), with detection limits of 0.72 μg mL−1 (2.4 × 10–6 M) for PA1 and 0.63 μg mL−1 (2.1 × 10–6 M) for PA2 in HClO4. The method was successfully applied for the evaluation of taxifolin in a food supplement, thereby demonstrating its practical applicability. This study is among the first to utilize both oxidation peaks of taxifolin in electroanalytical measurements. Comparisons between the results obtained using this technique and those from the UV–Vis spectrometry method confirmed the accuracy of the approach. © 2025 Elsevier B.V., All rights reserved.