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Tabebuia avellanedae naphthoquinones: activity against methicillin-resistant staphylococcal strains, cytotoxic
Eliezer Menezes Pereira1, Thelma de Barros Machado, Ivana Correa Ramos Leal
1Instituto de Microbiologia Prof, Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. pereiraem@ufrj.br
Background:
Methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococcus infections are a worldwide concern. Currently, these isolates have also shown resistance to vancomycin, the last therapy used in these cases. It has been observed that quinones and other related compounds exhibit antibacterial activity. This study evaluated the antibacterial activity, toxicity and in vivo dermal irritability of lapachol extracted from Tabebuia avellanedae and derivatives against methicillin-resistant staphylococcal isolates. In addition, its mechanism of action was also analyzed.
Methods:
The compounds beta-lapachone, 3-hydroxy beta N lapachone and alpha-lapachone were tested to determine the MIC values against methicillin-resistant S. aureus, S. epidermidis and S. haemolyticus strains, being the two last ones hetero-resistant to vancomycin. Experiments of protein synthesis analysis to investigate the naphthoquinones action were assessed. In vitro toxicity to eukaryotic BSC-40 African Green Monkey Kidney cell cultures and in vivo primary dermal irritability in healthy rabbits were also performed.
Results:
The compounds tested showed antibacterial activity (MICs of 8, 4/8 and 64/128 microg/mL to beta-lapachone, 3-hydroxy beta N lapachone and alpha-lapachone, respectively), but no bactericidal activity was observed (MBC > 512 microg/mL for all compounds). Although it has been observed toxic effect in eukaryotic cells, the compounds were shown to be atoxic when applied as topic preparations in healthy rabbits. No inhibition of proteins synthesis was observed.
Conclusion:
Our results suggest that quinones could be used in topic preparations against wound infections caused by staphylococci, after major investigation of the pharmacological properties of the compounds. Studies about the use of these compounds on tumoral cells could be carried on, due to their effect in eukaryotic cells metabolism.
Insights
Lapachol derivatives show antibacterial activity against resistant staphylococci. These compounds are safe for topical use in rabbits, suggesting potential for wound infection treatments.
Area of Science:
- Natural product chemistry
- Microbiology
- Pharmacology
Background:
- Antibiotic resistance in Staphylococcus aureus (MRSA) and coagulase-negative staphylococci is a global health threat.
- Vancomycin resistance in these bacteria necessitates novel therapeutic strategies.
- Quinone compounds, including lapachol derivatives, exhibit potential antibacterial properties.
Purpose of the Study:
- To evaluate the antibacterial activity of lapachol and its derivatives against MRSA.
- To assess the toxicity and dermal irritability of these compounds in vivo.
- To investigate the mechanism of action of these naphthoquinones.
Main Methods:
- Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays were performed against resistant staphylococcal strains.
- Protein synthesis inhibition assays were conducted.
- In vitro cytotoxicity and in vivo dermal irritation tests in rabbits were assessed.
Main Results:
- Lapachol derivatives demonstrated antibacterial activity with MICs ranging from 8 to 128 µg/mL.
- No bactericidal activity was observed (MBC > 512 µg/mL).
- Compounds were non-toxic and non-irritating in vivo for topical application, despite in vitro cytotoxicity.
Conclusions:
- Lapachol derivatives show promise for topical preparations against staphylococcal wound infections.
- Further research into the pharmacological properties is warranted.
- Potential applications in targeting tumoral cells due to effects on eukaryotic cell metabolism warrant investigation.
