Produção de metabólitos e atividades biológicas de fungos endofíticos associados à Annona jahnii Saff. do lavrado de Roraima

Abstract

Endophytic fungi are microorganisms that can live in association with plant species, inhabiting the interior of tissues and organs without causing damage to the host. These microorganisms are considered an alternative and promising source in the discovery of new natural products, since they have high capacity to synthesize secondary metabolites with chemical properties and biological activities of biotechnological interest. The objective of this work was to evaluate the metabolic production and antioxidant and antimicrobial potential of the extracts of endophytic fungi isolated from Annona jahnii. From the collection of microorganisms from the GBQF group, three fungal isolates were selected. The strains were reactivated, purified and preserved. In addition, they were characterized morphologically and identified by molecular techniques. To obtain the extracts the strains were cultured in liquid medium BDL, ISP2 and AVEIA, and incubated in shaker at 130rpm at temperatures of 18 ° and 26 ° C for 15 days. After the period, the fermented liquid was extracted with ethyl acetate using the liquid-liquid extraction technique. The extracts were chemically characterized by CCD, mass spectrometry with atmospheric pressure chemical ionization (APCI-EM) and high performance liquid chromatography until MSn fragmentation (CLAE-APCI-MS / MS). The antioxidant potential of the extracts was evaluated by the sequestering action of the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and by inhibiting the auto-oxidation of the β-carotene / linoleic acid system. The antimicrobial activity was determined by means of the Minimum Inhibitory Concentration (MIC) in Elisa plaques against the clinical pathogens E. coli, P. aeruginosa, S. aureus, E. faecalis and C. albicans. The selected endophytes were identified as Trichoderma harzianum, Penicillium sp and Aspergillus sp. Regarding the extracts, it was observed that the isolates produced more biomass when cultivated in BDL medium under the temperature of 26 ° C, with the most promising extracts EFASP (390.2mg) and EFPEN (348.3mg) respectively. Preliminary CCD prospecting of crude extracts revealed the presence of alkaloid, terpene and flavonoid compounds in all extracts. Analysis of extracts by APCI-MS in [M-H] + mode revealed that the extracts had distinct profiles. The chromatographic and spectrometric analyzes of the FR4 and FR17 fractions obtained from the EFASP extract presented similar profiles characteristic of the mixture and suggest the presence of isomeric compounds belonging to the class of cytochalasins. Regarding antioxidant activity, the DPPH method showed that the extracts EFASP (0.005mg / mL) and EFPEN (0.012mg / mL) presented the best antioxidant action. While in the auto-oxidation method of the β-carotene / linoleic acid system, the best potential was observed in the EFPEN extract (45.94%). In relation to the antimicrobial activity, it was verified that the extracts were active against the pathogens tested. The data obtained in this study show the potentiality of fungal extracts and highlight the importance of the study of endophytic fungi, which may be the source of new bioactive substances. In addition, these results are unprecedented for A. jahnii species.