In vitro antimicrobial activity of a new series of 1,4-naphthoquinones.
The antibacterial activity of a series of 1,4-naphthoquinones was demonstrated. Disk diffusion tests were carried out against several Gram-positive and Gram-negative bacteria. The compound 5-amino-8-hydroxy-1,4-naphthoquinone was the most effective, presenting inhibition zones measuring 20 mm against staphylococci, streptococci and bacilli at 50 microg/ml. Methicillin-resistant Staphylococcus aureus and several clinical isolates of this bacterium were also inhibited. Naphthazarin, 5-acetamido-8-hydroxy-1,4-naphthoquinone, and 2,3-diamino-1,4-naphthoquinone were the next most active compounds. The minimal inhibitory concentration of the active compounds was determined against S. aureus, ranging from 30 to 125 microg/ml. All compounds presented a minimal bactericidal concentration higher than 500 microg/ml, indicating that their effect was bacteriostatic. The EC50, defined as the drug concentration that produces 50% of maximal effect, was 8 microg/ml for 5-amino-8-hydroxy-1,4-naphthoquinone against S. aureus, S. intermedius, and S. epidermidis. These results indicate an effective in vitro activity of 5-amino-8-hydroxy-1,4-naphthoquinone and encourage further studies for its application in antibiotic therapy.
Departamento de Ciências dos Alimentos, Instituto de Ciências e Tecnologia de Alimentos, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
A
A
Riffel
L F
LF
Medina
V
V
Stefani
R C
RC
Santos
D
D
Bizani
A
A
Brandelli
D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D008087:Listeria / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D009285:Naphthoquinones / Q000737:chemistry / Q000494:pharmacology*; D012756:Sheep; D013211:Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification; D013291:Streptococcus / Q000187:drug effects
D000900:Anti-Bacterial Agents; D009285:Naphthoquinones; C005503:naphthazarin; C035342:1,4-naphthoquinone