Midecamycin

Midecamycin (CAS No. 35457-80-8) is a 16-membered macrolide antibiotic derived from Streptomyces mycarofaciens, with its core target being the A2058 site of bacterial ribosomal 23S rRNA; it exerts antibacterial effects by binding to the nascent peptide exit tunnel and inhibiting protein synthesis, while its antibacterial activity can be blocked and inactivated by glycosylation modification (e.g., with glucose and xylose) at the 2''-OH site. Its MIC values are predominantly concentrated in Gram-positive bacteria: the MIC₉₀ is 0.2 μg/ml for Streptococcus pneumoniae, 1.6 μg/ml for both MIC₅₀ and MIC₉₀ of Staphylococcus aureus, 0.4 μg/ml for MIC₅₀ and 1.6 μg/ml for MIC₉₀ of Streptococcus pyogenes, 1 μg/ml for Bacillus subtilis, 0.5 μg/ml for Enterococcus strain T30, and 25 μg/ml for MIC₉₀ of Bacteroides fragilis; by contrast, the MIC values exceed 100 μg/ml (indicating resistance) for Gram-negative bacteria such as Enterobacteriaceae and Pseudomonas aeruginosa. The commonly used concentrations are 0.05–64 μg/ml for antibacterial activity assays (via serial dilution method) and 1 mM for glycosylation reactions and enzymatic experiments. For clinical application, it is administered orally, with effective therapeutic concentrations ranging within the MIC scope of susceptible bacteria (≥0.25–3.1 μg/ml); it is indicated for the treatment of respiratory tract infections and mycoplasma infections. This agent features favorable oral absorption, no bitter taste, and milder gastrointestinal adverse reactions compared with erythromycin, while cross-resistance is observed between midecamycin and erythromycin.

References:

[1] Bonang G, Surjawidjaja JE, Santoso US. The in vitro activity of Midecamycin against various Vibrio species. Jpn J Exp Med. 1975 Feb;45(1):43-5. PMID: 1228226.

[2] Lin R, Hong LL, Jiang ZK, Li KM, He WQ, Kong JQ. Midecamycin Is Inactivated by Several Different Sugar Moieties at Its Inactivation Site. Int J Mol Sci. 2021 Nov 23;22(23):12636. doi: 10.3390/ijms222312636. PMID: 34884439; PMCID: PMC8657839.