Overcoming Mycobacterium tuberculosis Drug Resistance: Novel Medications and Repositioning Strategies.

Mycobacterium tuberculosis, the bacterium responsible for tuberculosis, is a global health concern, affecting millions worldwide. This bacterium has earned a reputation as a formidable adversary due to its multidrug-resistant nature, allowing it to withstand many antibiotics. The development of this drug resistance in Mycobacterium tuberculosis is attributed to innate and acquired mechanisms. In the past, rifampin was considered a potent medication for treating tuberculosis infections. However, the rapid development of resistance to this drug by the bacterium underscores the pressing need for new therapeutic agents. Fortunately, several other medications previously overlooked for tuberculosis treatment are already available in the market. Moreover, several innovative drugs are under clinical investigation, offering hope for more effective treatments. To enhance the effectiveness of these drugs, it is recommended that researchers concentrate on identifying unique target sites within the bacterium during the drug development process. This strategy could potentially circumvent the issues presented by Mycobacterium drug resistance. This review primarily focuses on the characteristics of novel drug resistance mechanisms in Mycobacterium tuberculosis. It also discusses potential medications being repositioned or sourced from novel origins. The ultimate objective of this review is to discover efficacious treatments for tuberculosis that can successfully tackle the hurdles posed by Mycobacterium drug resistance.

Ethyl Methane Sulfonate and Sodium Azide-Mediated Chemical and X-ray-Mediated Physical Mutagenesis Positively Regulate Peroxidase 1 Gene Activity and Biosynthesis of Antineoplastic Vinblastine in Catharanthus roseus.

Catharanthus roseus synthesizes bioactive therapeutic metabolites, known as monoterpenoid indole alkaloids (MIAs), including antineoplastic vinblastine and vincristine, which have high global demand, and antihypertensive ajmalicine, a serpentine. However, the in planta biosynthesis and accumulation of these phytopharmaceuticals are very low, attributed to their high cytotoxicity in the plant. Considering the low in planta concentration and over-harvesting of plant resources, biotechnological interventions have been undertaken to enhance the production of MIAs in plant systems. The present study was carried out to mutation through chemical and physical mutagenesis with sodium azide, ethyl methane sulfonate and X-rays, respectively, on C. roseus to determine their possible effects on the transcriptional modulation of MIA biosynthetic pathways in planta. The chemical mutagenesis resulted in delayed seed pod development in mutated C. roseus plants, with distinct leaf morphology and flower color. However, X-ray mutagenesis resulted in pollen-less sterile flowers. An HPLC analysis confirmed the higher catharanthine, vindoline and vinblastine content in sodium azide and X-ray mutants, and was further supported by higher PRX1 transcript levels estimated through real-time PCR analysis. The transcription factors WRKY1 and ORCA2 were found negatively regulated along with major MIA pathway genes in chemical mutants and their M1 generation, but showed positive regulation in X-ray M0 mutants. The induced mutagenesis of C. roseus provides a prospective strategy to modulate plant transcriptomes and enhance the biosynthesis of pharmaceutically important antineoplastic vinblastine in the plant.

Engineering Catharanthus roseus monoterpenoid indole alkaloid pathway in yeast.

Catharanthus roseus (Madagascar periwinkle), a medicinal plant possessing high pharmacological attributes, is widely recognized for the biosynthesis of anticancer monoterpenoid indole alkaloids (MIAs) - vinblastine and vincristine. The plant is known to biosynthesize more than 130 different bioactive MIAs, highly acclaimed in traditional and modern medicinal therapies. The MIA biosynthesis is strictly regulated at developmental and spatial-temporal stages and requires a well-defined cellular and sub-cellular compartmentation for completion of the entire MIAs biosynthesis. However, due to their cytotoxic nature, the production of vinblastine and vincristine occurs in low concentrations in planta and the absence of chemical synthesis alternatives projects a huge gap in demand and supply, leading to high market price. With research investigations spanning more than four decades, plant tissue culture and metabolic engineering (ME)-based studies were attempted to explore, understand, explain, improve and enhance the MIA biosynthesis using homologous and heterologous systems. Presently, metabolic engineering and synthetic biology are the two powerful tools that are contributing majorly in elucidating MIA biosynthesis. This review concentrates mainly on the efforts made through metabolic engineering of MIAs in heterologous microbial factories. KEY POINTS: • Yeast engineering provides alternative production source of phytomolecules • Yeast engineering also helps to discover missing plant pathway enzymes and genes.

Production of Effective Phyto-antimicrobials via Metabolic Engineering Strategies.

The emerging outbreak of infectious diseases poses a challenge and threatens human survival. The indiscriminate use and drying pipelines of antibiotic arsenals have led to the alarming rise of drug-resistant pathogens, projecting a serious concern. The rising antimicrobial resistance and redundancy of antibiotic discovery platforms (ADPs) have highlighted the growing concern to discover new antibiotics, necessitating exploring natural products as effective alternatives to counter drug resistance. Recently, plants have been extensively investigated in search of the "phytotherapeutics", attributed to their potential efficacy and tackling the majority of the drug-resistant mechanisms, including biofilms, efflux pumps, cell communication, and membrane proteins. However, major challenges in geographical fluctuations, low plant concentration, and over-harvestation of natural resources restrict availability and complete utilization of phyto-therapeutics as antimicrobials. Recent advances in scientific interventions have been instrumental in producing novel antimicrobials via metabolic engineering approaches in plant systems. The progress in plant genome editing, pathway reconstitution, and expression has defined new paradigms in the successful production of antimicrobials in the post-antibiotic era. The thematic review discusses the existing and emerging significance of phytotherapeutics in tackling antimicrobial resistance and employing metabolic engineering approaches. The prevailing scenario of antimicrobial resistance and the mechanisms, the traditional and modern drug-discovery approaches in addressing antimicrobial resistance, emphasizing advances in metabolic engineering approaches for antimicrobial production, and the plausible solutions for tackling drug-resistant pathogens, forms the key theme of the article.

Confirmation of "pre-plasmolysis mediated ex-osmosis hypothesis" to obtain shoot bud morphogenesis in Catharanthus roseus.

The antineoplastic herb, Catharanthus roseus is a classified high-value low-volume medicinal herb which is in global attention of scientific research for modulation of its monoterpenoid indole alkaloids (MIA) pathway through genetic engineering. These secondary metabolites are generally stored in specific types of structures/compartments due to their cytotoxic nature and designated roles in plant defense response. However, their presence can hinder the genetic engineering process used to develop transgenic plants through de novo morphogenesis and regeneration of plants from cultured cells/tissues and hence, it always remained a critical impediment in transgenic research in C. roseus. The pre-plasmolysis treatment of leaf explants can help to tackle the recalcitrant nature of leaf explant and can support the direct regeneration response by ex-osmosis that minimizes the concentration of alkaloids. Therefore, this study was performed to chase the effect of osmotic conditions on recalcitrant leaves of C. roseus engaged in vitro plant regeneration and hypothesis of alkaloids ex-osmosis is confirmed by HPLC analysis.

Publication rates after the first retraction for biomedical researchers with multiple retracted publications.

Retraction of scientific publications can unmask scientific misconduct. We undertook a survey of publication rates, for authors with multiple retractions in the biomedical literature, to determine whether they changed after authors' first retractions. We collected publication and citation data from Scopus for 100 authors with multiple retractions (either >10 retractions or 2-5 retractions) in the Retraction Watch database. Publication rates increased until the year of the first retraction and decreased rapidly thereafter. By 4 years after the first retraction, the proportion of authors actively publishing at least one paper/year was <50%, annual publication rates were <50% of the pre-retraction rate, and only 22% of authors had a publication rate >50% of their pre-retraction rate. There was no difference in the decline in publication rates between authors associated with a retraction for misconduct and those not associated with such a retraction. After the first retraction, citation rates of retracted papers declined whereas those of unretracted papers by the same authors remained unchanged. In summary, publication rates of authors with multiple retractions, most of whom were associated with scientific misconduct, declined rapidly after their first retraction but a small minority continued to publish regularly.