Fusarins G-L with Inhibition of NO in RAW264.7 from Marine-Derived Fungus Fusarium solani 7227.

Six new fusarin derivatives, fusarins G-L (1-6), together with five known compounds (5-11) were isolated from the marine-derived fungus Fusarium solani 7227. The structures of the new compounds were elucidated by means of comprehensive spectroscopic methods (1D and 2D NMR, HRESIMS, ECD, and ORC) and X-ray crystallography. Compounds 5-11 exhibited potent anti-inflammatory activity by inhibiting the production of NO in RAW264.7 cells activated by lipopolysaccharide, with IC50 values ranging from 3.6 to 32.2 µM. The structure-activity relationships of the fusarins are discussed herein.

Three Genes Involved in Different Signaling Pathways, carS, wcoA, and acyA, Participate in the Regulation of Fusarin Biosynthesis in Fusarium fujikuroi.

The phytopathogenic fungus Fusarium fujikuroi has a rich secondary metabolism which includes the synthesis of very different metabolites in response to diverse environmental cues, such as light or nitrogen. Here, we focused our attention on fusarins, a class of mycotoxins whose synthesis is downregulated by nitrogen starvation. Previous data showed that mutants of genes involved in carotenoid regulation (carS, encoding a RING finger protein repressor), light detection (wcoA, White Collar photoreceptor), and cAMP signaling (AcyA, adenylate cyclase) affect the synthesis of different metabolites. We studied the effect of these mutations on fusarin production and the expression of the fus1 gene, which encodes the key polyketide synthase of the pathway. We found that the three proteins are positive regulators of fusarin synthesis, especially WcoA and AcyA, linking light regulation to cAMP signaling. Genes for two other photoreceptors, the cryptochrome CryD and the Vivid flavoprotein VvdA, were not involved in fusarin regulation. In most cases, there was a correspondence between fusarin production and fus1 mRNA, indicating that regulation is mainly exerted at the transcriptional level. We conclude that fusarin synthesis is subject to a complex control involving regulators from different signaling pathways.