Contribuição para o conhecimento fitoquímico de Sida rhombifolia L. (Malvaceae) e avaliação da atividade antimicrobiana do seu óleo essencial ANDERSON ANGEL VIEIRA PINHEIRO JOÃO PESSOA – PB 2016

Abstract

Natural products are considered an extremely valuable source for the discovery of bioactive molecules. Thus, the objective was to make the phytochemical study of Sida rhombifolia L., characterize its fatty acids, determine the chemical composition and ethe antimicrobial activity of its essential oil. To the phytochemical study from the aerial parts of S. rhombifolia, the ethanol extract gross was obtained and, after the completion of phytochemical prospecting, underwent part of the extract of alkaloid march, acid chloroform phase was applied to a silica gel column. A partition was performed with the other portion of the extract and after obtaining the hydroalcoholic phase, this was applied to Amberlite XAD-2 column and then on Sephadex LH-20.Characterization of isolated compounds was given by Nuclear Magnetic Resonance (¹H and ¹³C). After extraction of fatty acids from S. rhombifolia, they were separated and quantified using a gas chromatograph with flame ionization detector. The compounds were identified by comparison with standards methyl ester (Sigma). To obtain the essential oil of S. rhombifolia, the plant leaves and flowers was submitted to hydrodistillation using a Clevenger apparatus (100 °C). The chemical analysis of the oil composition is made by a gas chromatograph coupled with mass spectrometry. The compounds were identified by comparing the mass spectrum obtained from the system database (NIST. 62 lib) and retention index (RI). Evaluation of the antimicrobial activity was due to the microdilution technique, using the essential oil of S. rhombifolia against Staphylococcus aureus (ATCC 15656), Escherichia coli (ATCC 25922), Streptococcus mutans (ATCC 25175), Pseudomonas aeruginosa (ATCC 27853) and Candida albicans (ATCC 1106). The phytochemical study allowed the isolation of ethoxy-ferulate (Sr- 1) and kaempferol (Sr-2). The analysis of fatty acids identified a percentage of 87.36%, of which palmitic acid (27.97%), linolenic acid (26.81%), and oleic acid (25.09%) were the most abundant in different percentages. The essential oil of S. rhombifolia presented as major constituents the octadecyl aldehyde (44.1%), p-vinyl guaiacol (19.4%) and linalool (15.1%). The evaluation of the antimicrobial activity of essential oil of S. rhombifolia showed activity moderate against Staphylococcus aureus (MIC - Minimum inhibitory Concentration 400 μg / ml) and Escherichia coli (MIC 350 μg / ml).