Diseases and pests constitute a major problem in agriculture. The present invention proposes a novel compound of formula (I) with biocidal activity, isolated from the fermentation product of endophytic fungi of the genus Guignardia sp. The invention also relates to the method of obtaining the compound of formula (I), to a fermentation product comprising it together with other known compounds that share structure and biocidal activity with the compound of formula (I), and to the use of said compounds as biocides, and especially as nematicides, either directly or through a composition, thereby constituting an effective method of controlling phytopathogens and pest organisms that affect plants.