Viridicatumtoxin A

Viridicatumtoxin A is a tetracycline-type polyketide originally described as a metabolite of Penicillium viridicatum and structurally related to the tetracycline class of antibiotics. Subsequent studies demonstrated strong antibacterial activity against Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), with potency comparable to vancomycin in related analogues. Mutagenicity assays in Salmonella typhimurium revealed activity after metabolic activation, consistent with its classification among biologically active mycotoxins. Biosynthetic and genomic analyses identified the viridicatumtoxin biosynthetic gene cluster and suggested horizontal gene transfer events between Aspergillus and Penicillium species. These findings define viridicatumtoxin A as a structurally unique tetracycline-type fungal antibiotic with potent anti-MRSA activity.