Penicillic acid (PA) is a polyketide mycotoxin produced by several species of Aspergillus and Penicillium species showed antibacterial activity against various plant pathogenic bacteria and can be as a lead molecule for the development of synthetic agrochemicals to control plant bacterial diseases. In addition, PA induces single-strand DNA breaks and inhibits DNA synthesis, demonstrating mutagenic and cytotoxic effects. Penicillic acid irreversibly inhibits GDP-mannose dehydrogenase (DMG), an alginate synthesis enzyme, interrupting the committed step in alginate biosynthesis.