Isolamento e quantificação de cercosporina em extrato de Cercospora brachiata

Abstract

In natural product chemistry, fungi are widely recognized for their role in the production of bioactive compounds with applications in various fields, such as health, agriculture, and industry. The Cercospora genus is known for its wide distribution and includes phytopathogenic species that produce important secondary metabolites, such as cercosporin. This compound, a perylenequinone with photodynamic properties, is responsible for causing necrosis in host plants and holds biotechnological potential, including applications in photodynamic therapies. Additionally, cercosporin exhibits atropoisomerism, interconverting into isocercosporin when in solution, a factor that complicates its isolation and characterization. In this study, the production of cercosporin by the fungus Cercospora brachiata, a species that has been scarcely explored scientifically, was investigated. Cercosporin was isolated from the fungal extract using chromatographic columns monitored by thin-layer chromatography (TLC). For improved isolation, high-performance liquid chromatography (HPLC) in semipreparative mode was employed to achieve better results. The compound was characterized by nuclear magnetic resonance (NMR) spectroscopy of 1H e 13C and subsequently quantified using analytical HPLC. Quantification was performed through analytical methods for constructing a calibration curve. The results demonstrated that approximately 20% of the extract consisted of cercosporin. This study not only highlights the relevance of Cercospora brachiata as a source of cercosporin and isocercosporin but also reinforces the importance of the genus Cercospora in natural product chemistry and the discovery of bioactive compounds with diverse applications.