Compostos majoritários presentes em óleos essenciais: caracterização antimicrobiana, toxicológica e antioxidante

Abstract

Each year, several essential oils and plant extracts are reported in the literature for presenting antimicrobial, anti-inflammatory, antioxidant, antimutagenic and even anticarcinogenic activities, and this action potential is mainly attributed to their major compounds. In this context, the present work aimed to evaluate the major compounds carvacrol, cinnamaldehyde and alpha-phellandrene regarding their potential antimicrobial, antioxidant in vivo and in vitro, cytotoxic effects and the toxicity profile in in vivo assays. The research was carried out in the research laboratories of the Universidade Tecnológica Federal do Paraná, Toledo campus and the compounds under evaluation were obtained by Sigma-Aldrich Brazil. The antimicrobial effect was evaluated through the Disco-diffusion tests, microdilution in broth to determine the Minimum Inhibitory Concentration (MIC) and Spot test to determine the Minimum Bactericidal and Fungicidal Concentration (CBM/CFM) against microorganisms of clinical interest. The antioxidant potential was determined through the in vivo test using mutant strains of Saccharomyces cerevisiae and in vitro tests using free radical scavenging techniques (DPPH and ABTS) and reducing power via FRAP. The toxicity of the compounds was evaluated by the lethality test using brine shrimp larvae and the cytotoxicity evaluated using fibroblast L929 strains and Vero cells. The compound that showed the best antimicrobial activity on the strains tested was carvacrol, with values between 0.02 and 1.82 mg.mL-1, followed by cinnamaldehyde with values between 0.20 and 0.98 mg.mL-1, whereas the compound alpha-phellandrene did not show antimicrobial potential at the concentrations tested. All compounds showed antioxidant potential in at least one of the in vitro tests, with the best antioxidant activity also being presented by carvacrol, which stood out in the three tests, mainly by the ABTS method, with a value of 8404.54 µmol ET/g of compound. In the evaluation of in vivo antioxidant activity, concentrations between 1 and 32 µg.mL-1 were not enough to verify the antioxidant potential of the compounds, and concentrations above this range showed an inhibitory effect against the strain used. The lethality test in Artemias indicated that all compounds showed 100% lethality, that is, in the tested concentrations between 0.06 and 1 mg.mL-1, the compounds showed an extremely toxic effect on the organisms. The cytotoxicity test showed that the compounds carvacrol and cinnamaldehyde are cytotoxic against the cell lines used. According to the results, the compounds carvacrol and cinnamaldehyde showed excellent antimicrobial potential against nine microorganisms of clinical interest, in addition to a great antioxidant potential, which was not observed with alpha-phelandrene. The lethality and cytotoxicity test bring some limitation in the application of compounds as herbal medicines or in foods, due to their toxicity.