New bioactive coumarins from Kielmeyera albopunctata

The CH(2)Cl(2) extract of the stem bark of Kielmeyera albopunctata was subjected to a bioassay-linked LC-MS dereplication procedure using the KB cell line to afford the new Coumarins 4-(1-methylpropyl)-5,7-dihydroxy-8-(4-hydroxy-3-methylbutyryl)-6-(3-methylbut-2-enyl)chromen-2-one (1), 9-(1-methylpropyl)-4-hydroxy-5-(4-hydroxy-3-methylbutyryl)-2-(1-hydroxy-1-methylethyl)-2,3-dihydrofuro[2,3-f]chromen-7-one (2), and 5,7-dihydroxy-8-(4-hydroxy-3-methylbutyryl)-6-(3-methylbut-2-enyl)-4-phenylchromen-2-one (3). Coumarins 1 and 3 showed moderate cytotoxicity, while 2 was inactive at 20 microg/mL. Compound 1was active in vitro against the trypomastigote form of the parasite Trypanosoma cruzi, killing 80% of the parasites after 24 h contact at 4 degrees C when added at 125 microg/mL to infected murine blood.