Abstract: In the field of agriculture, organisms that are harmful to vegetation are a major problem in relation to the productivity of harvests. The present invention relates to a fermentation product obtained from endophytic fungi of the Stemphylium solani family, which may comprise a novel compound of formula (I) and a second known compound of formula (II), and having biocidal activity simultaneously against more than one category of harmful organisms affecting plants, and which are preferably selected from insect-pests, fungi and nematodes. Both the fermentation product, and the compounds included in the scope of the invention, are used in the preparation of a broad-spectrum biocidal composition. Finally, the invention also includes the process for preparing of the fermentation product and the new compound of formula (I).