Biologically active alkylated coumarins from Kayea assamica

Four coumarin derivatives, theraphins A ( 1), B ( 2), C ( 3), and D ( 4), along with three known xanthones, 2-hydroxyxanthone, 1,7-dihydroxyxanthone, and 5-hydroxy-1-methoxyxanthone, were isolated from the bark of Kayea assamica (Clusiaceae) native to Myanmar. Their structures were determined using spectroscopic and chemical techniques. The absolute configuration of 1 was established by the modified Mosher ester method. Theraphins A ( 1), B ( 2), and C ( 3) exhibited good cytotoxicity against Col2, KB, and LNCaP human cancer cell lines. Theraphin D ( 4) showed mild activity only against the KB cell line. The coumarins also exhibited mild antimalarial activities. Theraphins A, B, C, and D, were isolated as cytotoxic principles from the bark of Kayea assamica (Clusiaceae) native to Myanmar.