Avaliação da atividade antioxidante e antibacteriana do extrato bruto e frações das folhas de Tetradenia riparia Hochst. Codd (Lamiaceae)

Abstract

Since human being earliest days, plants is used to diseases treatment due their therapeutic properties, once they are a source of biologically active compounds with great scientific interest for pharmaceutical, cosmetic and food industries. Nowadays, the pursuit for beneficial products to human and to environment has increased the research on antioxidant and antimicrobial areas due to the toxicity and resistance reports. This work aimed to evaluate antioxidant and antimicrobial activities of crude extract and fractions of Tetradenia riparia. Antioxidant action was evaluated through the DPPH scavenging (2,2-diphenyl- 1-picrylhydrazyl), β-Carotene/ linoleic acid assay, ferric reducing (FRAP) and total reactive antioxidant potential (TRAP). Column chromatographic fractionation provided 10m fractions, where among them the fraction gotten by the elution with ethyl acetate: methanol (8:2) (FR-IX) present promising results in relation to its antioxidant potential with 181,67 μg of gallic acid mg-1, CI50 of 0,61 μg mL-1, 55,61% of protection, 4,59 μM ferrous sulfate mg-1 and 4,15 μM of trolox in 62,5 μg mL-1, respectively. By nuclear magnetic resonance (NMR) in the FR-IX was detected the presence of astragalin, luteolon and boronolide. Antimicrobial activity was evaluated by broth microdilution method with the determination of the minimum inhibitory concentration (MIC), fraction obtained by dichloromethane mobile phases: hexane 7:3 and 8:2 (FR-II); dichloromethane: hexane 9:1 and dichloromethane 100% (FR-III) presented an antibacterial potential on ATCC 29213 Staphylococcus aureus strains with MIC of 1,95 and 0,98 μg mL-1, respectively. In this way, chromatographic fractioning was utmost important to detect the presence of fractions with superior antioxidant and antibacterial activities to the myrrh crude extract.