Antifungal secondary metabolites of an endophytic fungus of Picea abies

Botrytis cinerea is one of the most common agricultural pathogens which imposes significant economic loss of between 10 to 100 billion dollars annually [ 1 ]. Recent studies indicate that B. cinerea can develop resistance against conventionally used fungicides. Therefore, there is an increased demand for discovery of new potential fungicides to combat B. cinerea. An alternative approach for discovery of new antifungal agents against this emerging pathogen is utilizing the natural products derived from fungal endophytes. These symbiotic microbes are underexplored sources of bioactive substances and therefore hold a great potential for discovery of novel antifungals [ 2 ]. In this study, we aimed for isolation and identification of the bioactive metabolites of Paraleptosphaeria sp., an endophytic fungus isolated from the needles of Picea abies , and assessment of their antifungal activities against B. cinerea . The fungus was upscaled on a rice medium, then extracted using ethyl acetate. Subsequently, the extract was systematically separated by various chromatography techniques using silicagel, Sephadex LH-20, and C18, which ultimately yielded seven compounds. The structures of the compounds isolated were identified by 1&2-D NMR spectroscopy methods and LC-ESI-HRMS, resulting in three new (1-3) and three known (4-6) chromophilones, and a new versiol-like terpenoid (7). The absolute configuration of the compounds was established by comparison of experimental and calculated circular dichroism spectra. Ultimately, pure compounds were evaluated for their bioactivities against B. cinerea, among which compound 7 displayed promising antifungal activity. According to the results obtained, Paraleptosphaeria sp. can be considered as a promising source of unexplored secondary metabolites with potential antifungal activities. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany