Five known cardenolides, digitoxigenin (1), oleandrigenin (2), digitoxigenin alpha-L-cymaroside (3), digitoxigenin beta-gentiobiosyl-alpha-L-cymaroside (4), and delta 16-digitoxigenin beta-D-glucosyl-alpha-L-cymaroside (5), were isolated from the stems of Beaumontia brevituba Oliver by