Synthesis and antimycobacterial activity of capuramycin analogues. Part 1: substitution of the azepan-2-one moiety of capuramycin

A biocatalytic approach to capuramycin analogues by exploiting a substrate permissive N-transacylase CapW

“…12 CapW, which was previously identified as the enzyme catalyst responsible for this N-acylation, 14 was shown here to efficiently incorporate a variety of amine-containing substrates using mild, aqueous conditions and without the need for protection/deprotection of the hydroxyl groups within the acyl donor 8 . Unlike past semisynthetic efforts that relied on the precursor 6 , 13 which is produced in relatively low yields as the fifth most abundant congener when feeding the wild-type strain with AEC, our biocatalytic strategy took advantage of a recently reported ΔcapV mutant strain that produces predominantly the de- l -ACL capuramycin 7 with a relatively superior yield (17 mg/L compared to 2.9 mg/L for 6 ). 15 Not only did this provide a means to obtain ample precursor for the chemoenzymatic synthesis, it also enabled the establishment of a mutasynthetic platform, whose proof of concept was demonstrated with 10a .…”

“…7-11,13,21 What was not known prior to this effort, however, was whether substituting for the l -ACL had any effect on the activity of the hexuronic acid phosphotransferase, which we previously established is a mechanism of self-resistance by the producing strain. 16,17 A similar phenomenon is found within aminoglycoside producing strains that often encode for phosphotransferases to covalently modify and inactivate the self-made antibacterial product, and it has been established that identical mechanisms—often acquired through horizontal gene transfer—are employed by pathogens to render these antibiotics inactive.…”

“…Despite the relatively low yields (compared with 472 mg/L for 1 and 2 combined from nonsupplemented media), 6 has been used as a semisynthetic precursor to prepare a library of l -ACL-substituted capuramycins. 13 The synthesis utilized either a single-step substitution with excess amine and heat or a four-step procedure with protection, saponification, aminolysis, and deprotection. In contrast to the 1 and 2 producer, the de- l -ACL variants A-503083 F ( 7 ) and A-503083 E ( 8 ) are produced during standard fermentations (~3 mg/L and 1 mg/L, respectively, compared to 5 mg/L for 3 and 4 , combined).…”

Phospho-MurNAc-Pentapeptide Translocase (MraY) as a Target for Antibacterial Agents and Antibacterial Proteins

“…Researchers at Sankyo have carried out structure/function studies in the capuramycin family, by chemical modification of 46 [103]. A wide variety of amides were formed, of which a number of substituted phenylamino amides and phenylethylamino amides showed potent translocase I inhibition (IC 50 10-40 ng/ml) and anti-mycobacterial activity (MIC 6.25-12.5 µg/ml).…”

“…A wide variety of amides were formed, of which a number of substituted phenylamino amides and phenylethylamino amides showed potent translocase I inhibition (IC 50 10-40 ng/ml) and anti-mycobacterial activity (MIC 6.25-12.5 µg/ml). Most active was difluorophenyl amide (47), which showed activity against a range of Mycobacterium strains at MIC 0.5-2 µg/ml, with similar or better activity than isoniazid [103]. Acylation of capuramycin and 45 on the 2' hydroxyl group gave a further series of active compounds, of which the decanoyl derivative 48 showed very potent activity (MIC 0.06 µg/ml) against several Mycobacterium strains [104].…”