Antibacterial and Antibiofilm Activities of β-Lapachone by Modulating the Catalase Enzyme

Abstract

Background: Bacterial infections constantly have a large impact on public health, because of increased rates of resistance and reduced frequency of development of novel antibiotics. The utility of conventional antibiotics for treating bacterial infections has become increasingly challenging. The aim of the study was to assess the antibacterial effect of β-Lapachone (β-Lap), a novel synthetic compound. Methods: The antibacterial activity of the β-Lap compound was examined against laboratory strains by agar well diffusion method and broth dilution assay. Growth kinetics in presence of β-Lap on Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa (ATCC 27853) were assessed by microplate alamarBlue assay. Crystal violet blue assay was used for biofilm inhibition and biofilm eradication. P. aeruginosa catalase (KatA) complexed with β-Lap was modeled using molecular docking approach. Results: β-Lap exhibited potent antimicrobial activity against laboratory strains of bacteria with MIC of 0.2 mM for S. saprophyticus and Staphylococcus aureus, and 0.04 mM for Staphylococcus epidermidis and Pseudomonas aeruginosa ATCC 27853. The inhibition of catalase enzyme was found to be the cause for its antibacterial activity. Bioinformatics analysis suggests that β-Lap can inhibit KatA activity by interacting with catalase proximal active site and heme binding site. The activity of some commercial antibiotics was enhanced in association with β-Lap. In addition, β-Lap inhibited the biofilm formation and eradicated the already formed and ultra-mature biofilms of aforesaid bacterial strains. Conclusion: These observations indicated that β-Lap could be a promising antibacterial agent for the treatment and prevention of infectious diseases.

Design, synthesis, and unraveling the antibacterial and antibiofilm potential of 2-azidobenzothiazoles: insights from a comprehensive in vitro study

“…To ascertain if the compounds are bactericidal, the MBC assay was performed as per CSLI, 2016 guidelines ( Mir et al, 2023 ). MBC is the lowest concentration of compound that leads to a 3 log10-fold decrease in CFU units or the lowest drug concentration that results in 99.9% killing of bacterial cells in initial inoculums.…”

“…To determine whether compound 2d can inhibit the formation of biofilms, the Microtiter Plate Biofilm Assay was utilized as per described procedure ( O’Toole, 2011 ; Mir et al, 2023 ). Firstly, the compound was prepared as a working stock (200 µL of compound in first well) and was serially diluted two-fold to obtain a concentration ranging from 0.25 to 128 μg/mL in 8 individual 96-well plates (1 plate for inoculation of each bacterium) already containing 100 µL MHB (final volume of 200 µL).…”

Antimycobacterial and anticancer properties of Myrtus communis leaf extract

“…Agar well diffusion method is widely used to evaluate the antimicrobial activity of plant extracts. The zone of inhibition was determined as described [23] with slight modifications. Wells of 6 mm diameter were punched aseptically on TSA plates with a sterile tip.…”

“…MIC was determined by the broth dilution method as described [23] with slight modifications. In brief, 0.5 McFarland bacterial cultures in normal saline were 100-fold diluted in OADC-supplemented Middlebrook 7H9 media containing 1x alamarBlue.…”

“…The Microplate AlamarBlue ® assay (MABA) is a sensitive, rapid, and nonradiometric method that evaluates cellular health and offers the potential for screening large numbers of antimicrobial compounds. MABA was performed as described [23] with a slight modification. In brief, 190 μL of the 100-fold diluted culture of a bacterial strain in 2% glucose supplemented TSB containing 1× alamarBlue were dispensed into the wells of a 96-well plate.…”