Antimicrobial Activity and Chemical Constituents of <i>Siparuna guianensis</i> (Siparunaceae)

Siparuna guianensis (Siparunaceae) is an Amazonian plant known by the popular name of Negramina. There are several reports of the use of this plant in folk medicine. In the present work, we decided to study its extracts, aiming at the isolation of compounds and verifying their antimicrobial activities. After obtaining the extracts, the compounds were isolated through chromatographic methods and identified by nuclear magnetic resonance and mass spectrometry. The antimicrobial activities were performed through the microdilution method in 96-hole plates. Six compounds were isolated, two of which belong to the flavonoid class, kaempferol-3,7-dimethyl ether (1) and herbacetin 3,7-O-dimethyl ether (2), and four belong to the aporphine alkaloid class: isobulbocapnine (3), norlirioferine (4), liriodenine (5), and anonaine (6). Of the six compounds isolated from S. guianensis, compounds 3, 4, 5, and 6 are being reported for the first time in the species. The aporphine alkaloid compounds, isobulbocapnine (3) and norlirioferine (4) are being reported for the first time for the genus Siparuna. Compound 6 showed good activity against strains of phytopathogenic bacteria.