TY - BOOK

T1 - Synthesis of siderophore-based conjugates to detect and treat bacterial infections

AU - Ferreira, Kevin

N1 - Doctoral thesis

PY - 2018

Y1 - 2018

N2 - Infections caused by multidrug-resistant Gram-negative bacteria result in significant mortality and morbidity worldwide despite the development of new anti-infective drugs.[1] The need for novel antibiotics is currently not met by R&D efforts, in particular in the area of infections caused by Gram-negative bacteria. One of the scientific needs is to understand how to assure a sufficient translocation of bioactive molecules across the Gram-negative cell wall. Another limitation is the lack of reliable and sensitive methods that permit the detection of bacteria at early stages of infections where antibiotic treatments would still be effective.[2] One possibility to improve bacterial penetration is to generate conjugates and facilitate compound delivery through specific bacterial transport systems.[2] For example, iron is an essential actively transported nutrient: ferric siderophore complexes are internalized via recognition from the outer membrane and actively transported inside of Gram-positive and Gram-negative bacteria. Such stable, internalized complexes can be exploited with a so-called Trojan horse strategy. A series of agents comprising siderophores that actively target bacteria, inhibit bacterial growth and demonstrate efficacy to visualize bacterial infections were synthesized. This thesis shows the synthesis and structural characterization of various siderophores and conjugates, followed by an investigation of the siderophoric, labelling and antibiotic properties of the molecules. Designed conjugates were characterized as Fe(III) chelating agents. Among a list of 20 tested molecules on E. coli and P. aeruginosa, the DOTAM/catechol scaffolds showed high siderophoric effects. To quantify the intracellular accumulation of such conjugates, a fluorogen activating protein-based approach (FAP) that allows the determination of the subcellular localization of malachite green dye-coupled small molecules was pursued. This system served to validate the efficiency of vehicles for bacterial penetration.[3] The use of active targeting principles attached to the described DOTAM/Metal platform is expected to be appropriate for the development of new drug conjugates that have different cellular targets and modes of action against Gram-negative bacteria. The design and synthesis of novel BODIPY but also ampicillin, ciprofloxacin and sorangicin siderophore conjugates with a crucial demonstration of internalization described in this thesis represents a milestone towards improved theranostics against bacteria of the ESKAPE panel.

AB - Infections caused by multidrug-resistant Gram-negative bacteria result in significant mortality and morbidity worldwide despite the development of new anti-infective drugs.[1] The need for novel antibiotics is currently not met by R&D efforts, in particular in the area of infections caused by Gram-negative bacteria. One of the scientific needs is to understand how to assure a sufficient translocation of bioactive molecules across the Gram-negative cell wall. Another limitation is the lack of reliable and sensitive methods that permit the detection of bacteria at early stages of infections where antibiotic treatments would still be effective.[2] One possibility to improve bacterial penetration is to generate conjugates and facilitate compound delivery through specific bacterial transport systems.[2] For example, iron is an essential actively transported nutrient: ferric siderophore complexes are internalized via recognition from the outer membrane and actively transported inside of Gram-positive and Gram-negative bacteria. Such stable, internalized complexes can be exploited with a so-called Trojan horse strategy. A series of agents comprising siderophores that actively target bacteria, inhibit bacterial growth and demonstrate efficacy to visualize bacterial infections were synthesized. This thesis shows the synthesis and structural characterization of various siderophores and conjugates, followed by an investigation of the siderophoric, labelling and antibiotic properties of the molecules. Designed conjugates were characterized as Fe(III) chelating agents. Among a list of 20 tested molecules on E. coli and P. aeruginosa, the DOTAM/catechol scaffolds showed high siderophoric effects. To quantify the intracellular accumulation of such conjugates, a fluorogen activating protein-based approach (FAP) that allows the determination of the subcellular localization of malachite green dye-coupled small molecules was pursued. This system served to validate the efficiency of vehicles for bacterial penetration.[3] The use of active targeting principles attached to the described DOTAM/Metal platform is expected to be appropriate for the development of new drug conjugates that have different cellular targets and modes of action against Gram-negative bacteria. The design and synthesis of novel BODIPY but also ampicillin, ciprofloxacin and sorangicin siderophore conjugates with a crucial demonstration of internalization described in this thesis represents a milestone towards improved theranostics against bacteria of the ESKAPE panel.

U2 - 10.15488/3571

DO - 10.15488/3571

M3 - Doctoral thesis

CY - Hannover

ER -