Perfil químico e atividade fungicida dos extratos de Fusarium equiseti: abordagem metabolômica e quimiométrica

Abstract

Fusarium equiseti is a phytopathogen responsible for several diseases in plants. This work reports a metabolomic study of F. equiseti through its cultivation in different nutritional media: BD (potato dextrose), BDL (potato dextrose-yeast), MPD (malt-peptone-dextrose) and MnTPL (mannitol- yeast); and variation in culture time: 7, 14, 21, 28 and 35 days. A preliminary analysis by CCD and HPLC of the extracts obtained showed that, in all nutritional media, the culture period of 14 days proved to be the most promising in the production of secondary metabolites. Thus, these extracts were selected for analysis by UPLC-QTOF-MSE, and the data of mass fragmentation were submitted to a comparative analysis in database. This procedure resulted in an attempt to identify 10 different secondary metabolites, of which the equisetin and cyclo-L-proliglicin compounds have reports in the literature for F. equiseti, whereas the compounds cis - 9,10 - epoxy stearic acid, capsenone, , cryptocine, phenyl acetaldehyde, fusapirone, fusarielin B, maculosin and glycooxycholic acid are being reported for the first time for the species. These extracts were subsequently tested for fungicidal activity against Colletotrichum musae, where the BDL extract (14 days) showed a greater inhibition in the growth of the pathogen. For this extract (BDL) new tests of antifungal activity were carried out, through the analysis of the extracts (7, 14, 21, 28 and 35 days), which showed the BDL extract to be the most active, corroborating the preliminary data. From these results, statistical analyzes were performed using the mass spectrometry data obtained for the extracts BD, BDL, MPD and MnTPL. The main components analysis (PCA) allowed to differentiate efficiently the metabolic profile of each of the extracts, which presented some similarities, but the BDL extract showed to be the most distinct. Thus, from the analysis of orthogonal partial least squares discrimination (OPLS-DA) together with the S-Plot and VIP graphs of the BDL extracts 14 days (more active) and BDL 28 days (less active) was possible to detect nine biomarkers present only in the active extract BDL (14 days), and consequently, possibly associated with the observed fungicidal activity. The results obtained demonstrated the chemical potential of F. equiseti in the biosynthesis of secondary metabolites through the influence of nutritional media and culture time, as well as the efficiency of the use of the UPLC-QTOF-MSE technique and chemometry in the identification of bioactive organic compounds.