Induced production of the novel glycolipid ustilagic acid C in the plant pathogen Ustilago maydis

Glycolipids have attracted interest from the pharmaceutical, cosmetic, and food industries, due to their unique chemical properties and interesting biological activities. The phytopathogenic fungus Ustilago maydis, a well-known producer of glycolipids, reportedly secretes large amounts of the glycolipid biosurfactant ustilagic acid under special culture conditions. Thus, we utilized chemical epigenetic modifiers, DNA methyltransferase (DNMT) inhibitors and/or histone deacetylase (HDAC) inhibitors, to induce the expression of silent biosynthetic pathways for isolating novel glycolipids produced by this fungus. HPLC analyses revealed that supplementations of the DNMT inhibitor 5-azacytidine and the HDAC inhibitor SBHA to the liquid culture of U. maydis induced the production of the novel glycolipid ustilagic acid C (1), along with the known ustilagic acid B (2). Glycolipids 1 and 2 displayed weak antifungal activities against Aspergillus terreus and Candida albicans.