Alquilcatecóis derivados do piperonal e orto-vanilina: síntese e avaliação da atividade antimicrobiana

Abstract

Phenolic lipids or alkylphenols comprise a broad class of natural products isolated from plants, bacteria, fungi, and some animals, and have many biological activities, such as antimicrobial and antiproliferative. These activities are mainly due to the ability of alkylphenols to interact with the phospholipids in biological membranes, which can result in biological events that lead to cell death. In this sense, this work aimed to synthesize alkylcatechols, specifically 3-(1-hydroxyalkyl)catechols with variable size of the alkyl side chain from ortho-vanillin, and 4-(1-hydroxyalkyl)catechols from the hydrolysis of the 1,3-dioxolane moiety of 5-(1-hydroxyalkyl)-1,3-benzodioxoles previously synthesized from piperonal. The structural analyzes were conducted by 1H and 13C NMR spectroscopy. The hydrolysis reactions, carried out by treating the starting materials with AlCl3, BF3 and p-TsOH, did not lead to the expected products, where the first promoted not only the removal of the acetal group, but also of the alkyl side chain, and the reaction with p-TsOH resulted in the formation of dimers. On the other hand, the synthesis of alkylcatechols from o-vanillin was successfully conducted through Grignard reactions, where three derivatives were synthesized from hexyl, octyl and decylmagnesium. These products were evaluated for antimicrobial activity against Staphylococcus aureus, Escherichia coli and Candida parapsilosis, and were found to be not active against bacteria, but moderately active against C. parapsilosis.