Atividade antimicrobiana do extrato bruto hidroalcoólico seco de folhas maduras de Psidium guajava L.

Abstract

The Psidium guajava L. ("guava") is popularly used in the treatment of various diseases. It is common to use teas from young leaves (sprouts) to combat the symptoms of gastrointestinal infection, already mature leaves and dry leaves are less cited. However, the sprouts are in small amount in the trees. The study of mature leaves is important to prove that they have enough active substances to keep antimicrobial activity found in sprouts. The objective of this study was to evaluate the antimicrobial activity and modulating of dry raw hydroalcoholic extract (EBHSPg) obtained from the mature leaves of Psidium guajava L. The material was collected in the garden of medicinal plants José de Abreu Matos and used for obtaining EBHSPg 10%. Through phytochemical tests, it was verified the presence of flavonoids, pirogálicos tannins, saponins and triterpenoids. The antimicrobial potential was determined by agar diffusion method, the Minimum Inhibitory Concentration (MIC) by the microdilution broth method and the Minimum Lethal Concentration (MLC) by counting technique microdrop on microbial strains reference Staphylococcus aureus ATCC 6538P, E. coli ATCC 10536, Pseudomonas aeruginosa ATCC 9027 , Salmonella cholerae-suis ATCC 10708 subespécie cholerae-suis ATCC 10231 and Candida albicans ATCC 10231. The modulating activity of the extract in action in clinical use antibiotics (Gentamicin 30μg, Cefoxitin 30μg, Ciprofloxacin 5μg and Ampicillin 10mg) was tested by disk diffusion method modified on P. aeruginosa, S. cholerae-suis and S. aureus, strains that showed higher sensitivity EBHSPg. The diffusion technique in agar, the S. cholerae-suis strain showed higher sensitivity, with the diameter of the inhibition zones 19-23 mm, followed by P. aeruginosa (7 to 11.5mm), S. aureus (7 to 10.5mm) and E. coli (7.5mm). But the EBHSPg at the tested concentrations showed no inhibition on C. albicans. The lowest concentration at which there was formation of HI was 25 mg / mL of extract, inhibiting the growth of S. cholerae-suis strains and P. aeruginosa. In the microdilution tests, the lowest CIM of EBHSPg was found to be 5 mg / ml for P. aeruginosa, and S. cholerae-suis. Could not determine the CLM in EBHSPg concentrations tested. The EBHSPg showed synergism only when associated with ampicillin on P. aeruginosa strains and S. cholerae-suis. The associations of other antibiotics used and EBHSPg have 77.8% and 22.20% of indifferent and antagonistic effect, respectively, on the strains tested. The results show that mature leaves of P. guajava L. have substances with antimicrobial activity, are able to positively modulate the activity of ampicillin on P. aeruginosa and S. cholerae-suis and may replace the use of young leaves. However, it isnecessary to do further research to determine the mechanism of action of this plant product, as well as new toxicity tests that provide the basis for the safe use of this plant by the population.