Current Topics in Medicinal Chemistry - Volume 21, Issue 27, 2021

The increasing danger of methicillin-resistant Staphylococcus aureus (MRSA) and the limited therapeutic options for invasive MRSA infections make an urgent demand for the development of novel anti-MRSA agents. Oxazolidinone derivatives could inhibit protein synthesis by acting on the ribosomal 50S subunit of the bacteria and prevent the formation of a functional 70S initiation complex, so oxazolidinones are a novel class of antimicrobial agents with potential activity against a wide range of clinically significant multidrug-resistant Gram-positive pathogens. However, oxazolidinones such as linezolid are associated with significant adverse events, and myelosuppression represents the main unfavorable side effects. Moreover, MRSA isolates that are resistant to oxazolidinones have already emerged. Hybridization of oxazolidinone with other antibacterial pharmacophores has the potential to interact with multiple targets or to counterbalance the known side effects associated with each pharmacophore. Thus, oxazolidinone-containing hybrids are useful scaffolds for the development of novel anti-MRSA agents. This review covers the recent advances of oxazolidinonecontaining hybrids with anti-MRSA activity developed in the last decade to set up the direction for the design and development of oxazolidinone-containing hybrids with high efficiency and low toxicity.

Staphylococcus aureus (S. aureus), recognized as one of the deadliest pathogens responsible for nosocomial and community acquired infections, is highly contagious and associated with significant morbidity and mortality. The increasing emergency and rapid spread of various forms of drug-resistant S. aureus have already posed a heavy burden on the world health system, but newfangled antibiotics are right now being created at a much slower pace than our developing requirement. Macrolides could inhibit protein synthesis by targeting the bacterial ribosome and are a class of basic and widely used antibacterial agents in clinical practice to control infections caused by various bacteria, including S. aureus. However, the emergence of bacterial resistance to macrolide antibiotics, particularly in Gram-positive bacteria such as macrolide-resistant S. aureus, has already become one of the significant obstacles for effective chemotherapy. Therefore, there is a critical need for the development of novel macrolide candidates. This review provides an overview of macrolide hybrids with potential activity against S. aureus, including drug-resistant forms developed in the recent decade, with special emphasis on the structure-activity relationships and mechanism of actions.

Background: Methicillin-resistant S. aureus (MRSA) has already tormented humanity and the environment for a long time and is responsible for many difficult-to-treat infections. Unfortunately, there are limited therapeutic options, and MRSA isolates with complete resistance to vancomycin, the first-line drug for the treatment of MRSA infections, have already emerged in recent years. Moxifloxacin retained activity against mutant bacterial strains with various levels of fluoroquinolones resistance and had a lower potential to select for resistant mutants. Isatin is a versatile structure, and its derivatives are potent inhibitors of many enzymes and receptors. The fluoroquinolone- isatin derivatives demonstrated excellent antibacterial activity against both drug-sensitive and drug-resistant organisms. The structure-activity relationship elucidated that incorporation of 1,2,3-triazole moiety into the C-7 position of fluoroquinolone skeleton was favorable to the antibacterial activity. Accordingly, fluoroquinolone derivatives with isatin and 1,2,3-triazole fragments at the side chain on the C-7 position are promising candidates to fight against drug-resistant bacteria. Objective: To explore more active moxifloxacin derivatives to fight against MRSA and enrich the structure-activity relationships. Methods: The synthesized moxifloxacin derivatives 7a-i and 14a-f were evaluated for their antibacterial activity against a panel of MRSA strains by means of standard two-fold serial dilution method. Results: The majority of the synthesized moxifloxacin derivatives were active against most of the tested MRSA strains with MIC values in a range of 1 to 64 μg/mL. The mechanistic investigations revealed that topoisomerase IV was one of the targets for antibacterial activity. Conclusion: These derivatives are useful scaffolds for the development of novel topoisomerase IV inhibitors.

Methicillin-resistant Staphylococcus aureus (MRSA), a leading cause of infections in human being and is usually associated with a multidrug-resistant profile, represents a significant health threat and public burden globally. The limited options of effective antibiotics motivate the search for novel anti-MRSA agents. Aminoglycoside antibiotics have been extensively applied in the medical field due to their desirable broad-spectrum antibacterial activity, especially for systemic infections caused by Gram-negative organisms. Recent studies demonstrated that aminoglycosides also possessed potential activity against MRSA, so aminoglycosides may be useful weapons to fight against MRSA. The present work aims to summarize the current scenario of aminoglycosides with anti- MRSA potential, covering articles published between 2010 and 2020. The structure-activity relationship and the mechanism of action are also discussed for the further rational design of novel potential drug candidates.

Staphylococcus aureus (S. aureus) is one of the most common pathogens and implicated in a wide range of infections. It is responsible for a high rate of morbidity and mortality and has already posed a great burden on the healthcare system. S. aureus strains have already generated resistance to almost all available antibiotics, due to which the World Health Organization stratified S. aureus as a high tier priority II pathogen. Glycosides, the secondary metabolites of many plants in nature, possess a variety of pharmacological properties, including antibacterial activity against S. aureus. The structural and mechanistic diversity make glycosides useful weapons against S. aureus. This review summarizes the recent studies on naturally-derived glycosides and provides a comprehensive summary regarding the status of the resources and the anti-S. aureus potential.