Síntese e avaliação antimicrobiana de novos ésteres derivados de timol, carvacrol e sais cinâmicos

Abstract

The wide applicability associated with the use of essential oils is based on its structural formulation that presents forms of modifications through various chemical reactions such as organic synthesis, this factor implies increasing the amount of synthetic products on an industrial scale. Thus, derivatives of thymol, carvacrol and cinnamic salts act as potential drugs for the most diverse biological applications. Both compounds and their derivatives have aromatic rings susceptible to chain substitution and elongation reactions, producing various physicochemical characteristics and even an effective bioactive potentiation for the treatment of bacterial, fungal and viral diseases. Thus, this work aimed to synthesize, characterize and evaluate the in vitro antimicrobial activity of new esters derived from thymol, carvacrol and cinnamic salts. Representing a series of sixteen final compounds, twelve of which unpublished, the compounds were prepared from four intermediates; 5-methyl-2-(1-methylethyl)-phenol or 2-methyl-5-(1-methylethyl)-phenol with potassium cinnamate, 3,4,5-trimethoxy cinnamic, 3-nitro cinnamic and 4-chloro cinnamic . After the proper characterizations by means of infrared spectroscopic techniques - IR, nuclear magnetic resonance - hydrogen (1H) and carbon (13C) NMR, it was possible to successfully conclude obtaining the final products in yields between 79 - 91%.Regarding the in vitro bacterial and fungal activities, of the 20 substances tested, 13 showed activities for both variations of microorganisms, minimizing growth with a Maximum Inhibitory Concentration - MIC that varied from 256 to 1024 μg mL-1 in all molecules. It is possible to infer that, for bacteria of the type S. aureus ATCC-25923 and S. epidermidis ATCC-12228, they presented the best for the final compounds 2-(2-isopropyl-5-methylphenoxy)-2-oxoethyl, (E) -2-isopropyl-5-methylphenyl 4-((3-(3,4,5 trimethoxyphenyl)acryloyl)oxy)butanoate, (E)-2-(2-isopropyl-5-methylphenoxy)-2-oxoethyl 3-(3-nitrophenyl)acrylate, (E)-2-isopropyl-5-methylphenyl 4-((3-(3 nitrophenyl)acryloyl)oxy)butanoate, (E)-5-isopropyl-2-methylphenyl 4-(cinnamoyloxy)butanoate , (E)-2-(5-isopropyl-2-methylphenoxy)-2-oxoethyl 3-(3-nitrophenyl) acrylate, (E)-5-isopropyl-2-methylphenyl 4-((3-(3-nitrophenyl) )acryloyl)oxy)butanoate, (E)-5-isopropyl-2-methylphenyl 4-((3-(4-chlorophenyl)acryloyl)oxy)butanoate and the intermediate 2-isopropyl-5-methylphenyl 4-chlorobutanoate. For fungi, C. parapsilosis ATCC-22019, C. albicans ATCC-90028 and C. albicans LM-22, the same cited compounds also showed the best potentials, with the exception of (E)-5-isopropyl-2-methylphenyl 4-((3-(4-chlorophenyl)acryloyl)oxy)butanoate which maintained high concentrations of 1024 μg mL-1. It is possible to prioritize the best results for the 3-NO2 group as a substituent on the aromatic ring, which was determinant regardless of the chain and the isomer, being effective for all microbiological strains tested.