Neeta Thapliyal

Electroanalysis of antitubercular drugs in pharmaceutical dosage forms and biological fluids: A review

Tuberculosis remains a major global public health problem. Given the need for extensive analysis of antitubercular drugs, the development of sensitive, reliable and facile analytical methods to determine these compounds becomes necessary. Electrochemical techniques have inherent advantages over other well-established analytical methods, this review aiming to provide an updated overview of the latest trends (from 2006 till date) in the voltammetric determination of antitubercular drugs. Furthermore, the advantages and limitations of these methods are critically discussed. The review reveals that in spite of using a variety of chemically modified electrodes to determine antitubercular drugs, there is still a dearth of applicability of the voltammetric methods to quantify these compounds in human body fluids, especially in blood plasma.

An insight on synthetic and medicinal aspects of pyrazolo[1,5-a]pyrimidine scaffold.

Pyrazolo[1,5-a]pyrimidine scaffold is one of the privileged hetrocycles in drug discovery. Its application as a buliding block for developing drug-like candidates has displayed broad range of medicinal properties such as anticancer, CNS agents, anti-infectious, anti-inflammatory, CRF1 antagonists and radio diagnostics. The structure-activity relationship (SAR) studies have acquired greater attention amid medicinal chemists, and many of the lead compounds were derived for various disease targets. However, there is plenty of room for the medicinal chemists to further exploit this privileged scaffold in developing potential drug candidates. The present review briefly outlines relevant synthetic strategies employed for pyrazolo[1,5-a]pyrimidine derivatives. It also extensively reveals significant biological properties along with SAR studies. To the best of our understanding current review is the first attempt made towards the compilation of significant advances made on pyrazolo[1,5-a]pyrimidines reported since 1980s.

Conducting polymer-based electrochemical biosensors for neurotransmitters: A review

Neurotransmitters are important biochemical molecules that control behavioral and physiological functions in central and peripheral nervous system. Therefore, the analysis of neurotransmitters in biological samples has a great clinical and pharmaceutical importance. To date, various methods have been developed for their assay. Of the various methods, the electrochemical sensors demonstrated the potential of being robust, selective, sensitive, and real time measurements. Recently, conducting polymers (CPs) and their composites have been widely employed in the fabrication of various electrochemical sensors for the determination of neurotransmitters. Hence, this review presents a brief introduction to the electrochemical biosensors, with the detailed discussion on recent trends in the development and applications of electrochemical neurotransmitter sensors based on CPs and their composites. The review covers the sensing principle of prime neurotransmitters, including glutamate, aspartate, tyrosine, epinephrine, norepinephrine, dopamine, serotonin, histamine, choline, acetylcholine, nitrogen monoxide, and hydrogen sulfide. In addition, the combination with other analytical techniques was also highlighted. Detection challenges and future prospective of the neurotransmitter sensors were discussed for the development of biomedical and healthcare applications.

Design and synthesis of VEGFR-2 tyrosine kinase inhibitors as potential anticancer agents by virtual based screening

Vascular endothelial growth factor receptor-2 (VEGFR-2) plays a crucial role in cancer angiogenesis. A library of 6,7-dimethoxy quinazoline was prepared using a ligand based drug design approach and passed through different filters of virtual screening such as a docking study and Lipinskis rule. Twenty virtually screened compounds were synthesized and investigated against VEGFR-2 kinase and human umbilical vein endothelial cells (HUVEC) in vitro. Virtually screened compound 47 having 4-chlorophenyl-1,3,4-thiadiazole substitution at 3rd position of 6,7-dimethoxy-2-phenylquinazolin-4-(3H)-one exhibited the most promising activity, with IC50 values of 3.8 nm and 5.5 nm against VEGFR-2 tyrosine kinase and the HUVEC cell line. Docking simulation supported the initial pharmacophoric hypothesis and suggested a common mode of interaction at the ATP-binding site of VEGFR-2 demonstrating that compound 47 is a potential agent for cancer therapy that deserves further research.

Fabrication of highly sensitive gold nanourchins based electrochemical sensor for nanomolar determination of primaquine

A gold nanourchins modified glassy carbon electrode (AuNu/GCE) was developed for the determination of antimalarial drug, primaquine (PQ). The surface of AuNu/GCE was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and cyclic voltammetry (CV). EIS results indicated that the electron transfer process at AuNu/GCE was faster as compared to the bare electrode. The SEM and TEM image confirmed the presence and uniform dispersion of gold nanourchins on the GCE surface. Upon investigating the electrochemical behavior of PQ at AuNu/GCE, the developed sensor was found to exhibit high electrocatalytic activity towards the oxidation of PQ. Under optimal experimental conditions, the sensor showed fast and sensitive current response to PQ over a linear concentration range of 0.01-1μM and 0.001-1μM with a detection limit of 3.5nM and 0.9nM using differential pulse voltammetry (DPV) and square wave voltammetry (SWV), respectively. The AuNu/GCE showed good selectivity, reproducibility and stability. Further, the developed sensor was successfully applied to determine the drug in human urine samples and pharmaceutical formulations demonstrating its analytical applicability in clinical analysis as well as quality control. The proposed method thus provides a promising alternative in routine sensing of PQ as well as promotes the application of gold nanourchins in electrochemical sensors.

NiO–ZrO2 nanocomposite modified electrode for the sensitive and selective determination of efavirenz, an anti-HIV drug

The present study reports the synthesis of NiO–ZrO2 nanocomposites followed by their characterization using X-ray powder diffraction, high-resolution scanning electron microscopy, high-resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. A new chemically modified glassy carbon electrode was fabricated based on the synthesized nanocomposite and used as a highly sensitive electrochemical sensor for the determination of efavirenz, an anti-HIV drug. The modification increased the effective surface area of the sensor ten times in comparison to the bare glassy carbon electrode. Cyclic voltammograms revealed that the modified electrode exhibits excellent electrocatalytic activity towards oxidation of the drug. The current displayed a wide linear response ranging from 0.01 to 10 μM with a detection limit of 1.36 nM. The effect of interferents on the peak current response was studied. The electrode displayed advantages such as simple preparation, appreciable stability, reproducibility and high sensitivity. The feasibility of the proposed method was successfully demonstrated by determining efavirenz in commercial pharmaceutical formulations and human urine samples.

Electrochemically reduced graphene oxide/Poly-Glycine composite modified electrode for sensitive determination of l-dopa

A facile preparation strategy based on electrochemical technique for the fabrication of glycine (Poly-Gly) and electrochemically reduced graphene oxide (ERGO) composite modified electrode was developed. The morphology of the developed composite (ERGO/Poly-Gly) was investigated using field emission scanning electron microscope (FE-SEM). The composite modified glassy carbon electrode (GCE) was characterized using fourier transform-infrared (FT-IR) spectroscopy, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The electrochemical characterization results revealed that ERGO/Poly-Gly modified GCE has excellent electrocatalytic activity. Further, it was employed for sensing of l-dopa in pH5.5. Differential pulse voltammetry (DPV) was used for the quantification of l-dopa as well as for the simultaneous resolution of l-dopa and uric acid (UA). The LOD (S/N=3) was found to be 0.15μM at the proposed composite modified electrode. Determination of l-dopa could also be achieved in the presence of potentially interfering substances. The sensor showed high sensitivity and selectivity with appreciable reliability and precision. The proposed sensor was also successfully applied for real sample analysis.

A categorical review on electroanalytical determination of non-narcotic over-the-counter abused antitussive drugs

Dextromethorphan (DXM) and diphenhydramine (DPH) are two commonly used over-the-counter non-narcotic antitussive drugs. Recent reports reveal the widespread abuse of DXM and DPH due to their euphoric and alcohol-like effects. Due to their medicinal importance as well as the apparent increase in their use as abused drugs, it has become critical to determine them in samples of biological, clinical and pharmaceutical interest. The electrochemical techniques for drug analysis have gathered considerable attention due to their pronounced selectivity, sensitivity and simplicity. The given review presents a compilation of published voltammetric and potentiometric methods developed for determination of DXM and DPH. It critically highlights the analytical performances, revealing the recent trends and progress in the specified approach for their analysis. The review forms a basis for further progress in this field and development of improved electrochemical sensors to determine the drug.

Investigation of magnetic and electrochemical sensing properties of novel Ba1/3Mn1/3Co1/3Fe2O4 nanoparticles

Novel Ba1/3Mn1/3Co1/3Fe2O4 nanoparticles were successfully synthesized using the glycol thermal route. The X-ray diffraction study confirmed a well defined spinel phase structure of the sample. The microstrain was investigated based on the Williamson–Hall plot. Crystallinity, shape and size of the nanoparticles were studied using high resolution transmission electron microscopy and high resolution scanning electron microscopy. Brunauer–Emmet–Teller measurement revealed that the sample has a high surface area of 116 m2 g−1. The Barrett–Joyner–Halenda test showed that the sample is mesoporous. The magnetization was found to increase from 66.5 ± 0.3 emu g−1 at 300 K to 84.4 ± 0.5 emu g−1 at 4 K. Furthermore, the electrochemical sensing properties of Ba1/3Mn1/3Co1/3Fe2O4 nanoparticles were investigated using cyclic voltammetry. A glassy carbon electrode was modified using the synthesized Ba1/3Mn1/3Co1/3Fe2O4 nanoparticles. The modified electrode demonstrated excellent electrocatalytic activity towards didanosine, an anti-HIV drug. A linear response to the drug concentration was obtained in the range from 0.001 to 5.0 μM with a detection limit of 1.0 nM. The electrode was highly stable, reproducible and was successfully used to determine trace amounts of didanosine in human urine samples.

Research progress in electroanalytical techniques for determination of antimalarial drugs in pharmaceutical and biological samples

Antimalarial drugs play a crucial role in the treatment and cure of malaria. Electrochemical sensors have been the subject of extensive research in the field of drug analysis since many decades, and yet seem to project great potential for the future. The present review explores the basic strategies and recent developments in the electroanalysis of antimalarial drugs in various matrices. A discussion of the commonly used electroanalytical methods for drug assays is briefly discussed. The methods have been critically analysed highlighting their analytical performance and limitations. Nanomaterials, conducting polymers and presence of surfactants made significant contributions to voltammetric determination of antimalarial drugs suggesting promising future for use of chemically-modified electrode based sensors for the detection. Future progress in quantification of these drugs in biological fluids is expected to drastically improve the applicability of electrochemical methods for routine clinical analysis.