Evaluation of triterpenes isolated from stems of Pouteria macahensis T. D. Penn. against Proteus mirabilis

This article presents the results from a phytochemical study on an acetonic extract from the stems of Pouteria macahensis T.D. Penn., an endemic species of the Brazilian Atlantic Rainforest. By means of the bioautography method, this extract was evaluated against Acinetobacter baummanii, Proteus mirabilis, Escherichia coli and Staphylococcus epidermidis bacteria, of which only the P. mirabilis was found to be susceptible. The acetonic extract was chromatographed on a silica gel column, eluted with hexane and ethanol, producing 14 groups, allowing the isolation of the following compounds: friedelin, 3β-friedelinol and 3β-erythrodiol linoleate, arachidate and linolenate. Their structures were elucidated based on data of IR, 1H NMR, 13C NMR, including DEPT-135, HSQC and HMBC techniques. The minimum inhibitory concentrations of the compounds tested against P. mirabilis growth, were 500.0 μg mL^-1 for friedelin and erythrodiol and 600.0 μg mL^-1 for 3β-friedelinol and esterified 3β-erythrodiol. Based on these results, the potential of these compounds to inhibit the growth of this bacterium was confirmed.