Evaluation of the cytotoxicity and antibacterial activity of a synthetic tunicamycin derivative against Mycobacterium avium complex

Two synthetic derivatives of the tunicamycin antibiotic, TunR1 and TunR2, were previously developed that significantly reduced toxicity in eukaryotes but remained potent against Gram positive prokaryotes. TunR2 has been demonstrated to be non-toxic and effective in a zebrafish model of mycobacterial...

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Main Authors: Maria A. Colombatti Olivieri, Neil P. J. Price, Michael A. Jackson, John P. Bannantine
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-05-01
Series:Frontiers in Microbiology
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Online Access:https://www.frontiersin.org/articles/10.3389/fmicb.2025.1604400/full
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author Maria A. Colombatti Olivieri
Maria A. Colombatti Olivieri
Maria A. Colombatti Olivieri
Neil P. J. Price
Michael A. Jackson
John P. Bannantine
author_facet Maria A. Colombatti Olivieri
Maria A. Colombatti Olivieri
Maria A. Colombatti Olivieri
Neil P. J. Price
Michael A. Jackson
John P. Bannantine
author_sort Maria A. Colombatti Olivieri
collection DOAJ
description Two synthetic derivatives of the tunicamycin antibiotic, TunR1 and TunR2, were previously developed that significantly reduced toxicity in eukaryotes but remained potent against Gram positive prokaryotes. TunR2 has been demonstrated to be non-toxic and effective in a zebrafish model of mycobacterial infection. In this study, we evaluated the cytotoxicity in bovine cells and the antibacterial effect of natural Tun as well as two synthetic derivatives of Tun, designated TunR1 and TunR2, on Mycobacterium avium complex. The average minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) for TunR2 ranged from 16 to 32 μg/mL when tested on seven Mycobacterium avium subspecies paratuberculosis (Map) strains. MICs were higher for the closely related Mycobacterium avium subspecies hominissuis (>32 μg/mL), and lower for Mycobacterium marinum (0.025 μg/mL) and Mycobacterium smegmatis (3.2 μg/mL). Effects on the Map cell wall could be detected by electron microscopy at TunR2 concentrations above 128 μg/mL. The toxicity of TunR2 in eukaryotes was evaluated in vitro by hemolysis of bovine red blood cells (RBCs) and by MTT viability assay on a bovine epithelial cell line, cultured bovine peripheral blood mononuclear cells (PBMCs), and bovine monocyte-derived macrophages (bMDMs). The concentrations of the drug that produce 50% of inhibition (IC50) in each of these three cell types was lower than the MIC for Map. Hemolytic activity was demonstrated in 91% of RBCs when exposed to 31 μg/mL of TunR2. Also, low-dose TunR2 treatment of infected macrophages did not significantly decrease Map survival after 48 h of infection. These results suggest that TunR2 is not a good candidate to treat Map infections.
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spelling doaj-art-c7e24c2f858c4dca979bb8b55f06d74f2025-08-20T02:31:27ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2025-05-011610.3389/fmicb.2025.16044001604400Evaluation of the cytotoxicity and antibacterial activity of a synthetic tunicamycin derivative against Mycobacterium avium complexMaria A. Colombatti Olivieri0Maria A. Colombatti Olivieri1Maria A. Colombatti Olivieri2Neil P. J. Price3Michael A. Jackson4John P. Bannantine5National Animal Disease Center, USDA-Agricultural Research Service, Ames, IA, United StatesARS Participation Program, Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN, United StatesConsejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, ArgentinaNational Center for Agricultural Utilization Research, USDA-Agricultural Research Service, Peoria, IL, United StatesNational Center for Agricultural Utilization Research, USDA-Agricultural Research Service, Peoria, IL, United StatesNational Animal Disease Center, USDA-Agricultural Research Service, Ames, IA, United StatesTwo synthetic derivatives of the tunicamycin antibiotic, TunR1 and TunR2, were previously developed that significantly reduced toxicity in eukaryotes but remained potent against Gram positive prokaryotes. TunR2 has been demonstrated to be non-toxic and effective in a zebrafish model of mycobacterial infection. In this study, we evaluated the cytotoxicity in bovine cells and the antibacterial effect of natural Tun as well as two synthetic derivatives of Tun, designated TunR1 and TunR2, on Mycobacterium avium complex. The average minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) for TunR2 ranged from 16 to 32 μg/mL when tested on seven Mycobacterium avium subspecies paratuberculosis (Map) strains. MICs were higher for the closely related Mycobacterium avium subspecies hominissuis (>32 μg/mL), and lower for Mycobacterium marinum (0.025 μg/mL) and Mycobacterium smegmatis (3.2 μg/mL). Effects on the Map cell wall could be detected by electron microscopy at TunR2 concentrations above 128 μg/mL. The toxicity of TunR2 in eukaryotes was evaluated in vitro by hemolysis of bovine red blood cells (RBCs) and by MTT viability assay on a bovine epithelial cell line, cultured bovine peripheral blood mononuclear cells (PBMCs), and bovine monocyte-derived macrophages (bMDMs). The concentrations of the drug that produce 50% of inhibition (IC50) in each of these three cell types was lower than the MIC for Map. Hemolytic activity was demonstrated in 91% of RBCs when exposed to 31 μg/mL of TunR2. Also, low-dose TunR2 treatment of infected macrophages did not significantly decrease Map survival after 48 h of infection. These results suggest that TunR2 is not a good candidate to treat Map infections.https://www.frontiersin.org/articles/10.3389/fmicb.2025.1604400/fulltunicamycinMycobacterium avium complex (MAC)Mycobacterium paratuberculosis (MAP)cytotocixicityminimal inhibition concentration (MIC)
spellingShingle Maria A. Colombatti Olivieri
Maria A. Colombatti Olivieri
Maria A. Colombatti Olivieri
Neil P. J. Price
Michael A. Jackson
John P. Bannantine
Evaluation of the cytotoxicity and antibacterial activity of a synthetic tunicamycin derivative against Mycobacterium avium complex
Frontiers in Microbiology
tunicamycin
Mycobacterium avium complex (MAC)
Mycobacterium paratuberculosis (MAP)
cytotocixicity
minimal inhibition concentration (MIC)
title Evaluation of the cytotoxicity and antibacterial activity of a synthetic tunicamycin derivative against Mycobacterium avium complex
title_full Evaluation of the cytotoxicity and antibacterial activity of a synthetic tunicamycin derivative against Mycobacterium avium complex
title_fullStr Evaluation of the cytotoxicity and antibacterial activity of a synthetic tunicamycin derivative against Mycobacterium avium complex
title_full_unstemmed Evaluation of the cytotoxicity and antibacterial activity of a synthetic tunicamycin derivative against Mycobacterium avium complex
title_short Evaluation of the cytotoxicity and antibacterial activity of a synthetic tunicamycin derivative against Mycobacterium avium complex
title_sort evaluation of the cytotoxicity and antibacterial activity of a synthetic tunicamycin derivative against mycobacterium avium complex
topic tunicamycin
Mycobacterium avium complex (MAC)
Mycobacterium paratuberculosis (MAP)
cytotocixicity
minimal inhibition concentration (MIC)
url https://www.frontiersin.org/articles/10.3389/fmicb.2025.1604400/full
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