DMSO enhances the biosynthesis of epoxyquinols in Pestalotiopsis sp. (strain IQ-011) and yields new [4 + 2] cycloaddition dimers

Pestalotiopsis sp. (strain IQ-011) produces cuautepestalorin (10), a 7,8-dihydrochromene-oxoisochromane adduct featuring a spiro-polycyclic (6/6/6/6/6/6) ring system. Additionally, it yields its proposed biosynthetic precursors: cytosporin M (1) and oxopestalochromane (11) when cultured under standard conditions (fermentation in solid media). Following an OSMAC approach guided by metabolomic studies (PCA and molecular networks), it was established that the epigenetic modulator DMSO dramatically increases the production of 1 up to 50 times according to feature-based molecular networking (FBMN) analysis, and triggers the production of other derivatives from the epoxyquinol family. Chemo-targeted isolation resulted in the discovery of four new compounds: 19-hydroxycytosporin M (2) and three [4 + 2] cycloaddition products: ent-eutyscoparol J (4), ent-pestaloquinol A (6) and ent-pestaloquinol B (8). The structures of all isolates were established based on spectroscopic, spectrometric, chiroptical, and X-ray diffraction analyses. This study demonstrates the potential of combining metabolomic tools with DMSO as an epigenetic modulator to enhance fungal metabolite diversity and highlights the importance of chiroptical methods for accurate compound identification.