Chemical identification and evaluation of the antimicrobial activity of fixed oil extracted from Rhinella jimi.

CONTEXT: The toad Rhinella jimi (Stevaux, 2002) (Bufonidae) is used in traditional medicine to treat a number of illnesses (inflammation, infections, and wounds) in humans as well as animals.

OBJECTIVES

The present work examined the antimicrobial actions of the extracted oils from the body fat of R. jimi (ORJ) against fungi and standard and multi-resistant lines of bacteria, as well as their effects when combined with aminoglycosides.

MATERIALS AND

METHODS

The toads were collected in the municipality of Exu in Pernambuco State, Brazil, and their body fat oils extracted in a Soxhlet apparatus using hexane. A gas chromatograph coupled to a mass spectrometer was used to identify the fatty acids, based on their methyl esters. The antimicrobial activities of the oil were analyzed against standard and multi-resistant lines of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa, as well as against fungal lines of Candida albicans and Candida krusei using the broth micro-dilution method.

RESULTS

The minimum inhibitory concentrations (MIC) of ORJ were 512 µg/mL for Candida krusei and ≥1024 µg/mL for the other microorganisms. When associated with amikacin, ORJ demonstrated an increase in its ability to inhibit E. coli growth (from 156.25 to 39.06 µg/mL), indicating synergistic interaction. In the same way, when allied with amikacin, gentamicin, and neomycin, the ORJ reduced the MICs meaningly, against P. aeruginosa.

CONCLUSIONS

These data will enable searches to be made to obtain new products in combination with antibiotics, enhancing the efficacy of these drugs against drug-resistant microorganisms.