Avaliação da capacidade antimicrobiana de extratos de frutos de Morinda citrifolia L. (Rubiaceae)

Abstract

Noni is the fruit of the plant Morinda citrifolia L. (Rubiaceae), of Asian origin, used for millennia by native peoples of Polynesia and Tahiti, as a source of food and alternative medicine. It is widely used for the treatment of diabetes, hypertension, as a pain reliever and used as a treatment for the prevention of cancer. Both the fruit and the leaves have antioxidant, anti-inflammatory, healing and antiparasitic potential. Noni has several bioactive substances such as anthraquinones and coumarins that confer antimicrobial capacity. The objectives of the work were to characterize physicochemically the noni pulp, perform extractions of antimicrobial compounds with different solvents and test the antimicrobial capacity of these extracts against six microorganisms: Candida albicans, Candida tropicalis, Salmonella entérica typhimurium, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The methodology of successive extractions of solid-liquid in a shaker, with solvent renewal was used. The antimicrobial activity was tested by the disk diffusion and broth microdilution method. The physicochemical analyzes were carried out according to the procedures of Instituto Adolfo Lutz. The results obtained were 86% moisture, 0.64% total mineral residue, 0,78% total protein, 0.88% lipid, 0.206% total titratable acidity and 13°Brix total soluble solids. The disk-diffusion result showed positive inhibition in acetone and alcohol extracts, and no inhibition in the aqueous extract. The microdilution test in broth showed that strains of C. tropicalis were resistant to both alcoholic extract and acetone. The fungus C. albicans was the most sensitive to the alcohol extract, being inhibited at concentrations up to 1:100. The acetonic extract inhibited all the other strains used, at the concentration tested. Through this study it can be concluded that the results of the physicochemical characterization are in agreement with data from the literature and that the fractions of the extract of Morinda citrifolia fruits showed in vitro inhibition capacity against most of the tested microorganisms. The extraction process proved to be efficient in extracting metabolites with inhibitory activity.