C25-modified rifamycin derivatives with improved activity against Mycobacterium abscessus

Abstract

Infections caused by Mycobacterium abscessus are difficult to treat due to its intrinsic resistance to most antibiotics. Formation of biofilms and the capacity of M. abscessus to survive inside host phagocytes further complicate eradication. Herein, we explored whether addition of a carbamate-linked group at the C25 position of rifamycin SV blocks enzymatic inactivation by ArrMab, an ADP-ribosyltransferase conferring resistance to rifampicin. Unlike rifampicin, 5j, a benzyl piperidine rifamycin derivative with a morpholino substituted C3 position and a naphthoquinone core, is not modified by purified ArrMab. Additionally, we show that the ArrMab D82 residue is essential for catalytic activity. Thermal profiling of ArrMab in the presence of 5j, rifampicin or rifabutin shows that 5j does not bind to ArrMab. We found that the activity of 5j is comparable to amikacin against M. abscessus planktonic cultures and pellicles. Critically, 5j also exerts potent antimicrobial activity against M. abscessus in human macrophages and shows synergistic activity with amikacin and azithromycin.

Redesign of Rifamycin Antibiotics to Overcome ADP‐Ribosylation‐Mediated Resistance

“…In the work by Combrink and co‐workers, various carbamates were installed on 3‐morpholino rifamycin S to evade ADP‐ribosylation and increase potency against Mycobacterium smegmatis and M. abscessus . [ 16 , 17 , 18 ] Two C‐25 malonates from 3‐morpholino rifamycin S were also reported by us [7] and other groups [19] to exhibit improved activity against a panel of different bacteria including M. abscessus . However, most of the reported C25‐modified analogs were demonstrated with only micromolar activity, which is not better than current anti‐ M. abscessus drugs such as amikacin.…”

Redesign of Rifamycin Antibiotics to Overcome ADP‐Ribosylation‐Mediated Resistance

“…In the work by Combrink and co-workers, various carbamates were installed on 3-morpholino rifamycin S to evade ADP-ribosylation and increase potency against Mycobacterium smegmatis and M. abscessus. [16][17][18] Two C-25 malonates from 3-morpholino rifamycin S were also reported by us [7] and other groups [19] to exhibit improved activity against a panel of different bacteria including M. abscessus. However, most of the reported C25modified analogs were demonstrated with only micromolar activity, which is not better than current anti-M. abscessus drugs such as amikacin.…”

“…The modification of rifamycin C25 position was previously explored. In the work by Combrink and co‐workers, various carbamates were installed on 3‐morpholino rifamycin S to evade ADP‐ribosylation and increase potency against Mycobacterium smegmatis and M. abscessus [16–18] . Two C‐25 malonates from 3‐morpholino rifamycin S were also reported by us [7] and other groups [19] to exhibit improved activity against a panel of different bacteria including M. abscessus .…”

Exploring antibiotic resistance mechanisms in Mycobacterium abscessus for enhanced therapeutic approaches

“…RFB-5 m also had strong enhanced potency against all members of the Mab complex, other clinically relevant rapidly and slowly growing NTM, all of which encode Arr and block ADP-ribosylation (Ganapathy et al, 2023b). Recently, Paulowski et al reported that benzyl piperidine rifamycin derivative known as 5j, which possesses a morpholino substituted C3 position and a naphthoquinone core, does not undergo any modifications when exposed to pure Arr (Paulowski et al, 2022).…”