Bioatividade dos extratos de folhas de Echinodorus scaber Rataj e bioatividade e estudo químico de seus fungos endofíticos

Abstract

Echinodorus scaber Rataj (Synonymy Echinodorus macrophyllus), commonly known as a leather hat is a perennial herb found only in the wetlands of South America. Endophytic fungi represent a promising alternative to research of natural bioactive substances, as can biosynthesize metabolites with similar structures that was detected in their host. In popular medicine, the leaves of E. scaber Rataj are used for infusion mainly as anti-inflammatory, diuretic, to treatment of uric acid and rheumatism. The present work characterized the community of endophytic fungi cultivable from leaves of E. scaber by prepare leaf extracts and isolated fungi to evaluate the antimicrobial, antioxidant activities and obtain the phytochemical profile of these extracts, as well as isolating the active/potentially active compounds from the fungal extracts. A total of 138 strains were isolated from E. scaber leaves and separated into 19 morphotypes based on macro and microscopic characteristics. Colletotrichum gloeosporioides and Colletotrichum brevisporum were the most abundant species. The ethyl acetate extracts of these strains showed antioxidant and antibacterial activity. Among the 43 extracts tested, 20% demonstrated antibacterial activity and 88% antioxidant activity. For antibacterial activity, the Bipolaris oryzae-G15 and Curvularia geniculata-G8A extracts, showed activity at concentrations of 0.125 mg/mL and 0.03 mg/mL, respectively. Best results for antioxidant activity were obtained with Phoma sp.- G23 and Chaetomella raphigera-G13 extracts, both with 95% inhibition in the DPPH assay. 1H NMR spectra of extracts from E. scaber leaves and their fungi had characteristic signs alkyl groups, terpenoids and steroids and unsaturated compounds. Through the analysis of extracts of fungi by chromatographic techniques was possible isolated ten special metabolites. From Phoma sp.-G23, a triglyceride, (E)-2-(non-7-enoyloxy)propane-1,3-diyl dinonanoate, from Chaetomella raphigera-G28, the new substances 5-hydroxy-5-(methoxymethyl)- 2-oxo-4-phenyl-2,5-dihydrofuran-3-yl butyrate and 5,5-di((E)-hept-2-en-1-yl)-4- (4-hydroxyphenyl)-3-(methoxymethyl)furan-2(5H)-one, from Chaetomella raphigera-G13, 3-(4-hydroxy-5-oxo-3-phenyl-2,5-dihydrofuran-2-yl) propanoic acid, from Corynespora cassiicola-G2B, the naphthoquinone 7-Omethylspinochrome B (2,3,5-trihydroxy-7-methoxynaphthalene-1,4-dione), The unpublished naphthoquinone 3-butoxy-2,5,7-trihydroxy-6-methoxynaphthalene1,4-dione, determined as a casinone and decalactone (+)-1,3,9-trihydroxy-2- methoxy-11-methyl-4,8,10,13-tetrahydro-1H-benzo[d]oxecine-7,12-dione. Their structures were proposed by 1H, 13C, COSY, HMQC, HMBC NMR and mass spectrometry. Therefore, the leaves of E. scaber have a diversity of endophytic fungi, and these biosynthesize compounds with antioxidant and antibacterial activities.