platensimycin

Platensimycin (PTM) is an antibiotic produced by S. platensis that inhibits Gram-positve bacteria by selectively inhibiting cellular lipid biosynthesis (IC50 = 0.1 μM). It targets the β-ketoacyl-acyl-carrier-protein synthase I/II, FabF/B, an enzyme that participates in the biosynthesis of fatty acids (IC50s = 48 and 160 nM for S. aureus and E. coli enzymes, respectively). By specifically targeting fatty acid synthesis in bacteria, PTM is thought to be a promising agent for overcoming antibiotic resistance. PTM is also a selective inhibitor of the mammalian fatty acid synthase and has been shown to reduce liver triglyceride levels and to improve insulin sensitivity in a diabetic mouse model after an oral dose of 30 mg/kg.

Antimycobacterial agent-12 (Compound Ec42) is a Platensimycin derivative and acts as a dual inhibitor of KasA and KasB. It demonstrates minimum inhibitory concentrations (MIC) of 2 μg/mL against Staphylococcus aureus ATCC 29213, 2 μg/mL against Mycobacterium smegmatis, and 4 μg/mL against its isoniazid-resistant strains. In a Mycobacterium smegmatis-infected mouse model, Antimycobacterial agent-12 exhibits excellent antimycobacterial activity, making it a valuable tool for tuberculosis research.

Platencin is a natural, broad-spectrum Gram-positive antibiotic isolated from *S. platensis*, which is also the source of platensimycin. Platencin inhibits two key enzymes in bacterial fatty acid synthesis, β-ketoacyl-ACP synthases II and III (FabF and FabH, respectively), unlike platensimycin which only targets FabF. The IC50 values for platencin against FabF and FabH are 1.95 and 3.91 μg/ml, respectively. It does not exhibit cross-resistance to antibiotic-resistant bacterial strains, including methicillin-resistant *S. aureus*, vancomycin-intermediate *S. aureus*, and vancomycin-resistant Enterococci. For these reasons, platencin has potential applications in fighting antibiotic-resistant bacteria.