Synthesis and antibacterial activity of novel 3-O-carbamoyl derivatives of clarithromycin and 11,12-cyclic carbonate azithromycin

Synthesis and Antibacterial Evaluation of a Series of 11,12-Cyclic Carbonate Azithromycin-3-O-descladinosyl-3-O-carbamoyl Glycosyl Derivatives

A novel series of 11,12-cyclic carbonate azithromycin-3-O-descladinosyl-3-O-carbamoyl glycosyl derivatives were designed, synthesized, and evaluated for their antibacterial activities in vitro. Most of these compounds had significant antibacterial activity against seven kinds of susceptible strains. In particular, compound G1 exhibited the most potent activity against methicillin-resistant Streptococcus pneumoniae 943 (MIC: 1 μg/mL), Staphylococcus pneumoniae 746 (MIC: 2 μg/mL), Streptococcus pyogenes 447 (MIC: 8 μg/mL), and Escherichia coli 236 (MIC: 32 μg/mL), which were two-, four-, four-, four-, and eight-fold stronger activity than azithromycin, respectively. Additionally, compound G2 exhibited improved activity against methicillin-resistant Staphylococcus aureus MRSA-1 (MIC: 8 μg/mL), Streptococcus pneumoniae 943 (MIC: 2 μg/mL), Staphylococcus pneumoniae 746 (MIC: 2 μg/mL), and Escherichia coli 236 (MIC: 32 μg/mL), which were two-, two-, four-, and eight-fold better activity than azithromycin, respectively. As for methicillin-resistant Staphylococcus aureus MRSA-1, compound G6 presented the most excellent activity (MIC: 4 μg/mL), showing four-fold higher activity than azithromycin (MIC: 16 μg/mL) and erythromycin (MIC: 16 μg/mL). However, compared with other compounds, compounds G7 and G8 with the disaccharide side chain were observed the lower activity against seven strains.

Synthesis and antibacterial activity of novel 3-O-descladinosylazithromycin derivatives

Novel series of novel 3-O-arylalkylcarbamoyl descladinosylazithromycin derivatives with the 2'-O-acetyl and 11,12-cyclic carbonate groups, the 11,12-cyclic carbonate group and the 11-O-arylalkylcarbamoyl side chain, and 2'-O-arylalkylcarbamoyl descladinosylazithromycin with the 11,12-cyclic carbonate group were designed, synthesized and evaluated for their antibacterial activity using broth microdilution method. The results showed that the majority of the target compounds showed moderate to favorable activity against six kinds of susceptible strains and almost all of them displayed significantly improved activity compared with references against three erythromycin-resistant strains of S. pneumoniae B1 expressing the ermB gene, S. pneumoniae AB11 expressing the ermB and mefA genes, and S. pyogenes R1. In particular, compound 6h exhibited the most potent activity against susceptible B. subtilis ATCC9372 (0.5 μg/mL), penicillin-resistant S. epidermidis (0.125 μg/mL), and erythromycin-resistant S. pneumoniae B1 (1 μg/mL) and S. pneumoniae AB11 (1 μg/mL), which were 2-, 2-, 256-, 256-fold better activity than azithromycin, respectively. Additionally, compounds 6f (0.5 μg/mL) and 6g (0.25 μg/mL) were the most active against S. pneumoniae A22072, which were 8- and 16-fold better activity than azithromycin (4 μg/mL). As for erythromycin-resistant S. pyogenes R1, compound 5a presented the most excellent activity (8 μg/mL), showing 32- and 32-fold higher activity than azithromycin (256 μg/mL) and clarithromycin (256 μg/mL).

Novel 3-O-carbamoyl erythromycin A derivatives (carbamolides) with activity against resistant staphylococcal and streptococcal isolates

A novel series of 3-O-carbamoyl erythromycin A derived analogs, labeled carbamolides, with activity versus resistant bacterial isolates of staphylococci (including macrolide and oxazolidinone resistant strains) and streptococci are reported. An (R)-2-aryl substituent on a pyrrolidine carbamate appeared to be critical for achieving potency against resistant strains. Crystal structures showed a distinct aromatic interaction between the (R)-2-aryl (3-pyridyl for 4d) substituent on the pyrrolidine and G2484 (G2505, Escherichia coli) of the Deinococcus radiodurans 50S ribosome (3.2Å resolution).

Structure-activity relationships of novel alkylides: 3-O-arylalkyl clarithromycin derivatives with improved antibacterial activities

A series of novel alkylides, possessing 3-O-arylalkyl group instead of 3-O-cladinose, were designed, synthesized and evaluated for in vitro antibacterial activities. The increased potency clearly ranked by the order of 3-O-(3-aryl-2-propargyl), 3-O-(3-aryl-E-prop-2-enyl), 3-O-(3-aryl-propyl), and 3-O-(3-aryl-Z-prop-1-enyl) groups. Some alkylides, exemplified by 7a, 10a, 21, 22, 26, 27 and 33, showed improved activities against inducible MLS(B) resistance and efflux resistance compared to the second-generation macrolides. Among them, 26 possessed comparable activities against erythromycin-susceptible Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes (MICs of 0.016-0.5 μg/mL). Moreover, 26 displayed dramatically enhanced potency against both efflux resistant and inducibly MLS(B) resistant strains (MICs of 0.125-0.5 μg/mL) resistant to clarithromycin and azithromycin (MICs of 1- >254 μg/mL), independent of methicillin-susceptible and methicillin-resistant phenotypes.