Browsing by Author "Flaherty, Daniel P."

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    Dithiocarbamates effectively inhibit the alpha-carbonic anhydrase from Neisseria gonorrhoeae
    Giovannuzzi, Simone; Abutaleb, Nader S.; Hewitt, Chad S.; Carta, Fabrizio; Nocentini, Alessio; Seleem, Mohamed N.; Flaherty, Daniel P.; Supuran, Claudiu T. (Taylor & Francis, 2022-01-01)
    Recently, inorganic anions and sulphonamides, two of the main classes of zinc-binding carbonic anhydrase inhibitors (CAIs), were investigated for inhibition of the alpha-class carbonic anhydrase (CA, EC 4.2.1.1) from Neisseria gonorrhoeae, NgCA. As an extension to our previous studies, we report that dithiocarbamates (DTCs) derived from primary or secondary amines constitute a class of efficient inhibitors of NgCA. K(I)s ranging between 83.7 and 827 nM were measured for a series of 31 DTCs that incorporated various aliphatic, aromatic, and heterocyclic scaffolds. A subset of DTCs were selected for antimicrobial testing against N. gonorrhoeae, and three molecules displayed minimum inhibitory concentration (MIC) values less than or equal to 8 mu g/mL. As NgCA was recently validated as an antibacterial drug target, the DTCs may lead to development of novel antigonococcal agents.
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    In vitro and in vivo activities of the carbonic anhydrase inhibitor, dorzolamide, against vancomycin-resistant enterococci
    Abutaleb, Nader S.; Elhassanny, Ahmed E. M.; Flaherty, Daniel P.; Seleem, Mohamed N. (PeerJ, 2021-03-30)
    Vancomycin-resistant enterococci (VRE) are a serious public health threat and a leading cause of healthcare-associated infections. Bacterial resistance to antibiotics recommended for the treatment of enterococcal infections complicates the management of these infections. Hence, there is a critical need for the discovery of new anti-VRE agents. We previously reported carbonic anhydrase inhibitors (CAIs) as new potent VRE inhibitors. In the present study, the activity of the CAI, dorzolamide was evaluated against VRE both in vitro and in vivo. Dorzolamide exhibited potent activity against a panel of clinical VRE isolates, with minimum inhibitory concentration (MIC) values ranging from 1 µg/mL to 8 µg/mL. A killing kinetics experiment determined that dorzolamide exhibited a bacteriostatic effect against VRE, which was similar to the drug of choice (linezolid). Dorzolamide interacted synergistically with gentamicin against four strains of VRE, and exhibited an additive interaction with gentamicin against six VRE strains, reducing gentamicin’s MIC by several folds. Moreover, dorzolamide outperformed linezolid in an in vivo VRE colonization reduction mouse model. Dorzolamide significantly reduced the VRE burden in fecal samples of mice by 2.9-log10 (99.9%) and 3.86-log10 (99.99%) after 3 and 5 days of treatment, respectively. Furthermore, dorzolamide reduced the VRE count in the cecal (1.74-log10 (98.2%) reduction) and ileal contents (1.5-log10 (96.3%)) of mice, which was superior to linezolid. Collectively, these results indicate that dorzolamide represents a promising treatment option that warrants consideration as a supplement to current therapeutics used for VRE infections.
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    Structure-activity relationship studies for inhibitors for vancomycin-resistant Enterococcus and human carbonic anhydrases
    An, Weiwei; Holly, Katrina J.; Nocentini, Alessio; Imhoff, Ryan D.; Hewitt, Chad. S.; Abutaleb, Nader S.; Cao, Xufeng; Seleem, Mohamed N.; Supuran, Claudiu T.; Flaherty, Daniel P. (Taylor & Francis, 2022-12-31)
    Vancomycin-resistant enterococci (VRE), consisting of pathogenic Enterococcus faecalis and E. faecium, is a leading cause of hospital-acquired infections (HAIs). We recently repurposed the FDA-approved human carbonic anhydrase (CA) inhibitor acetazolamide (AZM) against VRE agent with the likely mechanism of action for the molecules being inhibition of one, or both, of the bacterial CA isoforms expressed in VRE. To elucidate how inhibitor binding to the enzymes relates to MIC, we further characterised the inhibition constants (K (i)) against the E. faecium alpha-CA (Ef alpha-CA) and gamma-CA (Ef gamma-CA), as well as against human CA I (hCAI) and human CA II (hCAII) to assess selectivity. We have also utilised homology modelling and molecular dynamics (MD) simulations to gain a better understanding of the potential interactions the molecules are making with the targets. In this paper, we elaborate on the SAR for the AZM analogs as it pertains to MIC and K (i) for each CA.