RESUMEN
Four novel triterpenoid saponins, 1α,3ß,23-trihydroxy-olean-12-en-28-oic acid 28-O-ß-glycopyranoside ester (1), 1α,3ß,23-trihydroxy-urs-12-en-28-oic acid 28-O-ß-glycopyranoside ester (2), 3-O-ß-galloyl-1α,23-dihydroxy-olean-12-en-28-oic acid 28-O-ß-glycopyranoside ester (3) and 3-O-ß-galloyl-1α,23-dihydroxy-urs-12-en-28-oic acid 28-O-ß-glycopyranoside ester (4) and two new pentacyclic triterpenoids, 3-O-ß-trans-p-coumaroyl-1α-hydroxy-urs-12-en-28-oic acid (5) and 3-O-ß-cis-p-coumaroyl-1α-hydroxy-urs-12-en-28-oic acid (6), together with six known compounds were isolated from the ethanolic extracts of Miconia burchellii leaves and stem bark. Their structures were established by HR-MS, 1D and 2D NMR and comparison with literature data. Additionally, the antimicrobial activity of the leaves and stem bark extracts and fractions was evaluated using the micro broth dilution technique. The crude extract, the ethyl acetate and methanol fractions of the stem bark were the most active against the tested bacteria, showing growth inhibition of both Gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa). To the best of our knowledge, this is the first study to report on the antimicrobial activity of M. burchellii.
RESUMEN
In this work was described the phytochemical investigation of Machaerium opacum Vogel (Fabaceae) leaves as well as the insecticidal activity of its crude extract and fractions against Atta sexdens Linnaeus (Hymenoptera: Formicidae). The phytochemical study led to the identification of α-amyrin, ß-amyrin, lupeol, phytol, isomucronulatol and rutin, described for the first time in M. opacum and mucronulatol. Insecticidal activity was assessed by the ingestion of the crude extract and fractions incorporated into an artificial diet at three different concentrations (0.2, 1.0 and 2.0 mg mL-1). Statistical analysis revealed that all the samples of M. opacum at all concentrations tested showed significant results when compared to the pure diet control.