Materials and methods
Marine samples
Marine sponges and tunicates were collected by SCUBA diving at depths ranging from 20 to 50 ft in Baler, Aurora, Davao Oriental, and Davao Gulf, Davao, Philippines. The sample were properly documented and stored in the freezer. Vouchers for bioassay were prepared by soaking a small piece of the organism in 100% methanol. Aliquots of the methanol extracts were dried and redissolved in normal saline solution (NSS, 0.9% NaCl). A 50 mg/ml stock solution of each sample was prepared for preliminary screening.