The Alternative Voltammetric Method for the Determination of Nicotine and Its Metabolite Nicotine N-Oxide

In the present paper, for the first time, the electrochemical behaviour of nicotine metabolite nicotine N-oxide (NNO) on static mercury dropping electrode (SMDE) and mercury meniscus modified silver solid amalgam electrode (m-AgSAE) has been reported. Nicotine N-oxide is reduced forming one peak at the potential -0.78 V on SDME and -0.86 V on m-AgSAE in Britton-Robinson buffer medium at pH 4.5 using cyclic voltammetry (CV). One electron and one proton take part in the reaction of NNO reduction. Calibration graphs for NNO determination using linear sweep voltammetry (LSV) on SDME and square-wave voltammetry (SWV) and differential pulse voltammetry (DPV) on m-AgSAE were obtained. Limit of detection (LOD) is 0.13 μM on SDME, and 0.16 μM (SWV) and 0.29 μM (DPV) on m-AgSAE. Since NNO can be used as an analytical form for nicotine voltammetric determination, so the developed methods were applied for the analysis of pharmaceutical preparations, and the recoveries from 97.3 to 104.6 % were achieved. Also, the elaborated methods were used in the analysis of biological fluids, and tobacco products. The obtained results were compared to those indicated in the certificates of drugs analysis, and to the results, obtained by reference methods (HPLC and GC).

Transmission of Multidrug/Rifampicin-Resistant Mycobacterium Tuberculosis in Chongqing, China: A Retrospective Observational Study Using Whole-Genome Sequencing

Background: Multidrug/rifampicin-resistant tuberculosis (MDR/RR-TB) is a global barrel for ‘Stop TB plan’. China has the second highest MDR/RR-TB burden in whole world wide. Understanding the transmission dynamic is facilitated for disease control. Methods: Whole genome sequencing (WGS) data from patients of Chongqing tuberculosis control institute were used for phylogenetic classifications, resistance predictions, and cluster analysis as indicator for recent transmission (RT). Factors associated with MDR/RR-TB were defined by a logistic regression model. Results: A total of 223 cases of MDR/RR-TB were recorded between Jan 1, 2018 and Dec 31, 2020, and 200 cases obtained relevant treatment information. The patients who are older than 55 year old were more likely to suffering from death. 178 MDR/RR strains were obtained WGS data, 152 were classified as lineage 2 strains. 80 (44.9%, 80 of 178) strains were in 20 genomic clusters that differed by 12 or fewer single nucleotide polymorphisms (SNPs), indicating RT. Patients who were infected with lineage 2 strains is a significant factor driving the epidemic towards MDR/RR-TB. Resistance mutations of first-line tuberculosis drugs analysis found that 79 (98.8%) of all 80 strains defined as RT have same mutations among each clusters totally. 55% (44 of 80) of the MDR/RR-TB strains accumulated additional drug resistance mutations along the transmission chain, especially fluoroquinolones (FQs) (63.6%, 28 of 44). Conclusions: The age is the most significant factor that causes death of MDR/RR-TB patients. RT of MDR/RR strains is not only drove the MDR/RR-TB epidemic, but also accumulated more serious resistance along the transmission chains.

A chemoinformatic analysis of atoms, scaffolds and functional groups in natural products

In the quest to know why natural products (NPs) have often been considered as privileged scaffolds for drug discovery purposes, many investigations into the differences between NPs and synthetic compounds have been carried out. Several attempts to answer this question have led to the investigation of the atomic composition, scaffolds and functional groups (FGs) of NPs, in comparison with synthetic drugs analysis. This chapter briefly describes an atomic enumeration method for chemical libraries that has been applied for the analysis of NP libraries, followed by a description of the main differences between NPs of marine and terrestrial origin in terms of their general physicochemical properties, most common scaffolds and “drug-likeness” properties. The last parts of the work describe an analysis of scaffolds and FGs common in NP libraries, focusing on huge NP databases, e.g. those in the Dictionary of Natural Products (DNP), NPs from cyanobacteria and the largest chemical class of NP – terpenoids.

The study of NMR spectroscopy use in pharmaceutical analysis

Drug products are specific goods. A customer cannot determine quality and authenticity of any tablet, ointment or ampule content himself. As number of registered drugs has been increasing the actuality of quality assurance and standardization of drugs becomes much important. At the same time highly active substances belonging to new natural and synthetic drugs classes has been coming in medicinal practice. NMR spectroscopy approach has wide opportunities in increasing number of drugs analysis which must meet constantly increasing demands.