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A partir de la resina, obtenida de la corteza, de P. carana March (Burseraceae), se aisló una mezcla de a- y ß-amirina. Mediante acilación se obtuvo la mezcla de los respectivos derivados acetilados y por oxidación una mezcla de 3-oxo- a-amirina y 3-oxo-ß-amirina cuyas estructuras fueron determinadas mediante estudios espectroscópicos (IR, RMN- 1H y RMN-13C). Se determinó la actividad antibacteriana de los derivados contra Staphylococcus aureus (ATCC 25923), Klebsiella pneumoniae (ATCC 23357), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922) y Enterococcus faecalis (ATCC 19433). Encontrándose que poseen Concentración Inhibitoria Mínima (CIM) y Concentración Bactericida Mínima (CBM) superiores a 400 µg/mL. Un estudio de la actividad antioxidante mostró que los derivados son inactivos. La resina contiene una alta concentración de a/ß-amirinas. From P. carana March (Burseraceae) resin, a mixture of a-amyrin and ß-amyrin was obtained. Acylation of this mixture yielded the mixture of the acetylated derivatives; on the other hand, oxidation yielded a mixture of the 3-oxo-a- amyrin and 3-oxo-ß-amyrin. The molecular structures were confirmed by spectroscopic studies (IR, 1H and 13C NMR). The Antimicrobial activity of these compounds were determined against Staphylococcus aureus (ATCC 25923), Klebsiella pneumoniae (ATCC 23357), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922) and Enterococcus faecalis (ATCC 19433), it was found that Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were over 400 µg/mL. It was also determined that the derivatives did not show any anti-oxidant activity. The resin contains a high concentration of a/ß-amirinas. 9-15 rojasl@ula.ve usubilla@ula.ve jujar@ula.ve Semestral