Mutagenicity of lichen constituents

Area of Science:

• Pharmacology and Toxicology
• Natural Products Chemistry
• Microbiology

Background:

• Lichens are a symbiotic association of fungi and algae, known to produce a diverse array of secondary metabolites.
• Usnic acid, physodic acid, and physodalic acid are common lichen compounds with potential biological activities.
• Assessing the genotoxicity of natural products is crucial for understanding their safety and potential applications.

Purpose of the Study:

• To evaluate the mutagenic potential of usnic acid, physodic acid, and physodalic acid.
• To investigate the mutagenicity of these compounds using the Ames Salmonella/microsome assay.

Main Methods:

• Compounds were isolated from the lichen Hypogymnia enteromorph.
• Mutagenicity testing was performed using the Ames Salmonella/microsome assay with Salmonella typhimurium strain TA 100.
• Tests were conducted with and without the addition of S9 mix, a metabolic activation system, using both plate-incorporation and preincubation methods.

Main Results:

• Physodalic acid demonstrated clear, dose-related mutagenicity against Salmonella typhimurium TA 100.
• Mutagenic effects of physodalic acid were observed both with and without S9 mix.
• The presence of S9 mix significantly increased the number of revertants, approximately threefold in preincubation and fourfold in plate-incorporation assays.

Conclusions:

• Physodalic acid isolated from Hypogymnia enteromorph exhibits mutagenic properties.
• The mutagenicity of physodalic acid is confirmed in the Ames test, suggesting potential genotoxic risks.
• Metabolic activation via S9 mix enhances the mutagenic activity of physodalic acid.