Potencial antifúngico da oleorresina de Copaifera arenicola do Ceará contra Fusarium spp. agentes causais da podridão da coroa em bananas

Abstract

Crown rot caused by a complex of fungi, including species of the genus Fusarium, is one of the most destructive postharvest diseases, responsible for significant economic losses in tropical fruits of high socioeconomic importance, such as Musa spp. (banana). The application of synthetic fungicides is the main method used to manage this disease; however, despite their effectiveness, their continuous use is associated with adverse environmental impacts. In this context, the oleoresin (OR) of Copaifera (copaiba) stands out as an effective and environmentally friendly alternative. The present study aimed, for the first time, to chemically characterize the OR of Copaifera arenicola using spectroscopic techniques, as well as to investigate the antifungal potential of the crude compound and its fractions against Fusarium triseptatum (BAN23), Fusarium sulawesiense (BAN119), and Fusarium fredkrugeri (BAN129), which cause crown rot in bananas. Botanical identification of the copaiba tree from Icapuí-CE was carried out, followed by OR collection. The material was fractionated into volatile (VOL) and non-volatile (NON) fractions by hydrodistillation. From the non-volatile fraction, adsorption chromatography was employed to obtain the precipitate (PPT) and the purified fraction containing hardwickiic and colavenic acids (HA). The OR and its fractions were characterized by Proton Nuclear Magnetic Resonance (¹H NMR) and Gas Chromatography coupled with Mass Spectrometry (GC-MS). Mycelial growth inhibition (MGI) and disk diffusion assays were performed to evaluate antifungal activity. Based on ¹H NMR and GC-MS analyses, the major compounds identified in the OR were hardwickiic and colavenic acids, along with the sesquiterpenes α-copaene (35.15%) and β-caryophyllene (15.91%). In the MGI assay, the highest mean inhibition values at a concentration of 16 mg·mL⁻¹ of OR were 29.00%, 25.30%, and 20.65% for BAN119, BAN129, and BAN23, respectively. These results are consistent with the degree of pathogenicity of the fungi and demonstrate the inhibitory potential of the OR even against more pathogenic species. In the disk diffusion assay, it was observed that the largest inhibition zone for each culture was produced by a different treatment, and the fungi showed greater sensitivity to less purified fractions due to the synergistic effect among the compounds. Thus, this study contributes to elucidating the chemical composition of copaiba oleoresin from Ceará and supports its use as an alternative control method for postharvest diseases in bananas.