Background: Antibacterial resistance is a serious public health problem infecting millions in
the global population. Currently, there are few antimicrobials on the market against resistant bacterial
infections. Therefore, there is an urgent need for new therapeutic options against these strains.
Objective: In this study, we synthesized and evaluated ten Bis(2-hydroxynaphthalene-1,4-dione) against
Gram-positive strains, including a hospital Methicillin-resistant (MRSA), and Gram-negative strains.
Methods: The compounds were prepared by condensation of aldehydes and lawsone in the presence of
different L-aminoacids as catalysts in very good yields. The compounds were submitted to antibacterial
analysis through disk diffusion and Minimal Inhibitory Concentration (MIC) assays.
Results: L-aminoacids have been shown to be efficient catalysts in the preparation of Bis(2-
hydroxynaphthalene-1,4-dione) from 2-hydroxy-1,4-naphthoquinones and arylaldehydes in excellent
yields of up to 96%. The evaluation of the antibacterial profile against Gram-positive strains (Enterococcus
faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, S. epidermidis ATCC 12228) also
including a hospital Methicillin-resistant S. aureus (MRSA) and Gram-negative strains (Escherichia coli
ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Klebsiella pneumoniae ATCC 4352), revealed
that seven compounds showed antibacterial activity within the Clinical and Laboratory Standards
Institute (CLSI) levels mainly against P. aeruginosa ATCC 27853 (MIC 8-128 µg/mL) and MRSA
(MIC 32-128 µg/mL). In addition, the in vitro toxicity showed all derivatives with no hemolytic effects
on healthy human erythrocytes. Furthermore, the derivatives showed satisfactory theoretical absorption,
distribution, metabolism, excretion, toxicity (ADMET) parameters, and a similar profile to antibiotics
currently in use. Finally, the in silico evaluation pointed to a structure-activity relationship related to
lipophilicity for these compounds. This feature may help them in acting against Gram-negative strains,
which present a rich lipid cell wall selective for several antibiotics.
Conclusion: Our data showed the potential of this series for exploring new and more effective antibacterial
activities in vivo against other resistant bacteria.