Antimicrobial substances from Amazonian () species.

Extracts and six isolated substances from () Amazonian species , and were analysed to their antibacterial, antiparasitic and antiplasmodial activities. NMR and MS experiments led to the identification of three styrylpyrones (5,6-dihydrokawain [I], 4-methoxy-11,12-methylenedioxy-6--styryl-pyran-2-one [II] and -(6R,7S,8S,5'S)-4'-methoxy-8-(11,12-dimethoxyphenyl-7-[6-(4-methoxy-2-pyranyl)]-6-()-styryl-1'-oxabicyclo[4,2,0]oct-4'-en-2'-one [III]), a pyridine alkaloid (anibine [IV]) and two kavalactones (tetrahydroyangonin [V] and dihydromethysticin [VI]). The best antibacterial result was observed at the hexane fraction of (MIC 7.8 μg/mL against the three bacteria). Equal MIC were observed by the extract and dichloromethane fraction of against and ; and 15.62 μg/mL against MRSA. Similarly, only extracts showed activities against and parasites. In assay, 5,6-dihydrokawain was considered an active antimalarial (14.03 μM), and substances II (132.94 μM) and III (41.84 μM) presented moderate activities.