Investigation of the antibacterial and antifungal activity of thiolated naphthoquinones

Abstract

The WHO has stated that antibiotic resistance is escalating to perilously high levels globally and that traditional therapies of antimicrobial drugs are futile against infections caused by resistant microorganisms. Novel antimicrobial drugs are therefore required. We report in this study on the inhibitory activity of the 1,4-naphthoquinone-2,3-bis-sulfides and 1,4-naphthoquinone sulfides against two bacteria and a fungus to determine their antimicrobial properties. The 1,4-naphthoquinone sulfides have potent activity with a minimum inhibitory concentration (MIC) of 7.8 µg/mL against Staphylococcus aureus (Gram +ve), an MIC of 23.4µg/mL against the fungus, Candida albicans, which was better than that of Amphotericin B (MIC = 31.3 µg/mL), and against Escherichia coli (Gram -ve) an MIC of 31.3 µg/mL was obtained. The 1,4-naphthoquinone had an MIC of 11.7 µg/mL against S. aureus and the 1,4-naphthohydroquinone also had the same activity against E. coli.