Investigations of two Flacourtiaceae plants, Bennettiodendron leprosipes and Flacourtia ramontchi, resulted in the isolation and structural elucidation of six new constituents including two phenolic glycosides ( 1 and 2), one lignan ( 3), two lignan glycosides ( 4 and 5), and a monoterpene glycoside ( 6), together with 22 known compounds ( 7- 28). The structures of the new compounds were elucidated by spectroscopic analysis and chemical methods. The selected isolates 1, 2, 8- 10, 22- 26, and some phenolic glycosides 29- 42 previously isolated from another Flacourtiaceae plant, Itoa orientalis, were tested against snake venom phosphodiesterase I (PDE I) activity. The result indicated that 22, 30, 32, 34, and 40 exhibited moderate inhibitory activities against PDE I with the values ranging from 13.15 to 20.86 %, and 1, 8, 10, 25, 31, 33, 35, 38, 39, and 41 showed weak inhibitory activity.