The antimicrobial activity of the myrsinoic acid A isolated from Myrsine coriacea (Sw.) R.Br. ex Roem. & Schult., Primulaceae, and a two semi-synthetics derivatives was tested against Bacillus subtilis, Escherichia coli, Salmonella enterica subsp. enterica serovar typhi, Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Micrococcus luteus, Candida albicans, Candida krusei and Candida tropicalis. The microdilution method was used for the determination of the minimum inhibitory concentration during evaluation of the antimicrobial activity. The myrsinoic acid A showed no activity against the selected microorganisms but the hydrogenated and acetylated derivatives were active against B. subtilis, E. coli, S. aureus and P. aeruginosa.