Synthesis and Antibacterial Activity of Novel Pleuromutilin Derivatives

Antibacterial and Antifungal Activity of Metabolites from Basidiomycetes: A Review

Background/Objectives: The search for new antimicrobial molecules is important to expand the range of available drugs, as well as to overcome the drug resistance of pathogens. One of the promising sources of antibacterial and antifungal metabolites is basidial fungi, which have wide biosynthetic capabilities. Methods: The review summarized the results of studying the antimicrobial activity of extracts and metabolites from basidiomycetes published from 2018-2023. Results: In all studies, testing for antibacterial and antifungal activity was carried out in in vitro experiments. To obtain the extracts, mainly the fruiting bodies of basidiomycetes, as well as their mycelia and culture liquid were used. Antimicrobial activity was found in aqueous, methanol, and ethanol extracts. Antimicrobial metabolites of basidiomycetes were isolated mainly from the submerged culture of basidiomycetes. Metabolites active against Gram-positive and Gram-negative bacteria and mycelial and yeast-like fungi were identified. Conclusions: Basidiomycete extracts and metabolites have shown activity against collectible strains of bacteria and fungi and multi-resistant and clinical strains of pathogenic bacteria. The minimum inhibitory concentration (MIC) values of the most active metabolites ranged from 1 to 16.7 µg/mL.

Synthesis and Antibacterial Activity of Alkylamine-Linked Pleuromutilin Derivatives

In an effort to expand the spectrum of the antibacterial activity of pleuromutilin, a series of amine- and polyamine-linked analogues were prepared and evaluated for activities against a panel of microorganisms. Simple C-22-substituted amino esters or diamines 16, 17, 18, and 22, as well as two unusual amine-linked bis-pleuromutilin examples 20 and 23, displayed variable levels of activity towards Staphylococcus aureus ATCC 25923 and methicillin-resistant S. aureus, but with no detectable activities towards Gram-negative bacteria. Fortunately, the incorporation of a longer-chain triamine or polyamine (spermine) at C-22 did afford analogues (30, 31) that exhibited activity towards both S. aureus ATCC 25923 and Escherichia coli ATCC 25922 with MIC 6.1-13.4 µM. Spermine-pleuromutilin analogue 31 was also able to enhance the action of doxycycline towards Pseudomonas aeruginosa ATCC 27853 by eight-fold, highlighting it as a useful scaffold for the development of new antibacterial pleuromutilin analogues that exhibit a broader spectrum of activity.

Design and Synthesis of Pleuromutilin Derivatives as Antibacterial Agents Using Quantitative Structure-Activity Relationship Model

The quantitative structure-activity relationship (QSAR) is one of the most popular methods for the virtual screening of new drug leads and optimization. Herein, we collected a dataset of 955 MIC values of pleuromutilin derivatives to construct a 2D-QSAR model with an accuracy of 80% and a 3D-QSAR model with a non-cross-validated correlation coefficient (r2) of 0.9836 and a cross-validated correlation coefficient (q2) of 0.7986. Based on the obtained QSAR models, we designed and synthesized pleuromutilin compounds 1 and 2 with thiol-functionalized side chains. Compound 1 displayed the highest antimicrobial activity against both Staphylococcus aureus ATCC 29213 (S. aureus) and Methicillin-resistant Staphylococcus aureus (MRSA), with minimum inhibitory concentrations (MICs) < 0.0625 μg/mL. These experimental results confirmed that the 2D and 3D-QSAR models displayed a high accuracy of the prediction function for the discovery of lead compounds from pleuromutilin derivatives.

Design, synthesis and antibacterial activity evaluation of pleuromutilin derivatives according to twin drug theory

A series of novel pleuromutilin derivatives were designed and synthesized based on the twin drugs theory. Piperazinyl and thioether were used as the linkage to connect the pleuromutilin nuclear and sulfonamide to improve the biological activity and water solubility of derivatives. The in vitro antibacterial activities against drug-sensitive and drug-resistance bacteria were evaluated by agar dilution method. Most of the 25 compounds displayed excellent antibacterial activities against drug-sensitive bacteria, particularly, five compounds (9, 10, 11, 14a and 14b) exerted the excellent antibacterial activities against drug-resistance bacteria.

Piperazine skeleton in the structural modification of natural products: a review

Piperazine moiety is a cyclic molecule containing two nitrogen atoms in positions 1 and 4, as well as four carbon atoms. Piperazine is one of the most sought heterocyclics for the development of new drug candidates with a wide range of applications. Over 100 molecules with a broad range of bioactivities, including antitumor, antibacterial, anti-inflammatory, antioxidant, and other activities, were reviewed. This article reviewed investigations regarding piperazine groups for the modification of natural product derivatives in the last decade, highlighting parameters that affect their biological activity.

Antibacterial Activity and Pharmacokinetic Profile of a Promising Antibacterial Agent: 22-(2-Amino-phenylsulfanyl)-22-Deoxypleuromutilin

A new pleuromutilin derivative, 22-(2-amino-phenylsulfanyl)-22-deoxypleuromutilin (amphenmulin), has been synthesized and proved excellent in vitro and in vivo efficacy than that of tiamulin against methicillin-resistant Staphylococcus aureus (MRSA), suggesting this compound may lead to a promising antibacterial agent to treat MRSA infections. In this study, the effectiveness and safety of amphenmulin were further investigated. Amphenmulin showed excellent antibacterial activity against MRSA (minimal inhibitory concentration = 0.0156~8 µg/mL) and performed time-dependent growth inhibition and a concentration-dependent postantibiotic effect (PAE). Acute oral toxicity test in mice showed that amphenmulin was a practical non-toxic drug and possessed high security as a new drug with the 50% lethal dose (LD50) above 5000 mg/kg. The pharmacokinetic properties of amphenmulin were then measured. After intravenous administration, the elimination half-life (T1/2), total body clearance (Clβ), and area under curve to infinite time (AUC0→∞) were 1.92 ± 0.28 h, 0.82 ± 0.09 L/h/kg, and 12.23 ± 1.35 μg·h/mL, respectively. After intraperitoneal administration, the T1/2, Clβ/F and AUC0→∞ were 2.64 ± 0.72 h, 4.08 ± 1.14 L/h/kg, and 2.52 ± 0.81 μg·h/mL, respectively, while for the oral route were 2.91 ± 0.81 h, 6.31 ± 2.26 L/h/kg, 1.67 ± 0.66 μg·h/mL, respectively. Furthermore, we evaluated the antimicrobial activity of amphenmulin in an experimental model of MRSA wound infection. Amphenmulin enhanced wound closure and promoted the healing of wound, which inhibited MRSA bacterial counts in the wound and decreased serum levels of the pro-inflammatory cytokines TNF-α, IL-6, and MCP-1.

Antibacterial properties and clinical potential of pleuromutilins

Covering: up to 2018Pleuromutilins are a clinically validated class of antibiotics derived from the fungal diterpene (+)-pleuromutilin (1). Pleuromutilins inhibit bacterial protein synthesis by binding to the peptidyl transferase center (PTC) of the ribosome. In this review we summarize the biosynthesis and recent total syntheses of (+)-pleuromutilin (1). We review the mode of interaction of pleuromutilins with the bacterial ribosome, which involves binding of the C14 extension and the tricyclic core to the P and A sites of the PTC, respectively. We provide an overview of existing clinical agents, and discuss the three primary modes of bacterial resistance (mutations in ribosomal protein L3, Cfr methylation, and efflux). Finally we collect structure-activity relationships from publicly available reports, and close with some forward looking statements regarding future development.

Design, synthesis and antibacterial evaluation of novel pleuromutilin derivatives possessing piperazine linker

A series of pleuromutilin derivatives bearing piperazine ring have been reported. The in vitro antibacterial activities of the synthetic derivatives against MRSA (ATCC 43300), Staphylococcus aureus (ATCC 29213), Enterococcus faecalis (ATCC 29212), Enterococcus faecium (ATCC35667) and Escherichia coli (ATCC25922) were evaluated by the broth dilution method. Most of the synthesized derivatives displayed potent activities. Compounds 11c, 12a and 12c were found to be the most active antibacterial derivatives against MRSA (minimum inhibitory concentration = 0.015 μg/mL). The binding of compounds 11c, 12a and 12c to the 50s ribosome were investigated by molecular modeling. Compound 11c possessed lower binding free energy compared with compounds 12a and 12c. Compound 11c was further evaluated in MRSA systemic infection model and displayed superior in vivo efficacy to that of tiamulin.

Mutations Associated with Decreased Susceptibility to Seven Antimicrobial Families in Field and Laboratory-Derived Mycoplasma bovis Strains

The molecular mechanisms of resistance to fluoroquinolones, tetracyclines, an aminocyclitol, macrolides, a lincosamide, a phenicol, and pleuromutilins were investigated in Mycoplasma bovis For the identification of mutations responsible for the high MICs of certain antibiotics, whole-genome sequencing of 35 M. bovis field isolates and 36 laboratory-derived antibiotic-resistant mutants was performed. In vitro resistant mutants were selected by serial passages of M. bovis in broth medium containing subinhibitory concentrations of the antibiotics. Mutations associated with high fluoroquinolones MICs were found at positions 244 to 260 and at positions 232 to 250 (according to Escherichia coli numbering) of the quinolone resistance-determining regions of the gyrA and parC genes, respectively. Alterations related to elevated tetracycline MICs were described at positions 962 to 967, 1058, 1195, 1196, and 1199 of genes encoding the 16S rRNA and forming the primary tetracycline binding site. Single transversion at position 1192 of the rrs1 gene resulted in a spectinomycin MIC of 256 μg/ml. Mutations responsible for high macrolide, lincomycin, florfenicol, and pleuromutilin antibiotic MICs were identified in genes encoding 23S rRNA. Understanding antibiotic resistance mechanisms is an important tool for future developments of genetic-based diagnostic assays for the rapid detection of resistant M. bovis strains.