Phytotoxic and antifungal compounds for agriculture are interestingly produced by the endophytic fungus Fusarium sp. (Ascomycota) isolated from Piper sp. (Piperaceae).

Abstract

Our study focused on the phytotoxic and antifungal activities of metabolites isolated from Fusarium sp., an endophyte associated with the medicinal plant Piper sp. Chromatographic separations of the Fusarium sp. crude extract led to the isolation of three analogous compounds: anhydrofusarubin (1), 5,10-dihydroxy-1,7-dimethoxy-3-methyl-1H-benzo[g]isochromene-6,9-dione (2), and javanicin (3). The structures of the isolated compounds were determined by high-resolution mass spectrometry (HRMS) analysis and direct comparison of 13C NMR data with that reported in the literature. The isolated compounds were evaluated for phytotoxic activity against Lactuca sativa and Agrostis stolonifera. All compounds exhibited strong phytotoxic activity on both plant species, completely inhibiting seed germination at a concentration of 1 mg mL-1. Additionally, the isolated compounds were evaluated against Lemna paucicostata, achieving a 50% growth inhibition (IC50) at concentration of 64, 28, and 31 μM for compounds 1, 2, and 3, respectively. The antifungal activity of these compounds was evaluated using a bioautography assay targeting the agricultural pathogen Colletotrichum fragariae. Among them, compound 2 demonstrated significant antifungal activity. Our results showed that tropical medicinal plants harbor an interesting endophyte that has a potential reservoir of bioactive compounds. Moreover, the structures of these compounds could serve as scaffold for the development of new pesticides.