*3.3. Extraction and Isolation*

The sample of the sponge *Halichondria vansoesti* was immediately frozen after collection and kept at −20 ◦C. The biological materials (dry weight 13.7 g) were chopped into small pieces and extracted with EtOH (200 mL × 3). The combined EtOH solution was concentrated to obtain the crude ethanol extract (7.9 g), which was partitioned between *n*-hexane and aqueous EtOH (9:4). The aqueous ethanol-soluble materials (6.4 g) was concentrated and further fractionated by CC on YMC-GEL (2.5 × 15 cm) and eluted successively with H2O→EtOH:H2O (3:7)→EtOH:H2O (2:3)→EtOH:H2O (1:1)→EtOH:H2O (3:2). Each of the subfractions obtained by elution with EtOH:H2O (3:7) to EtOH:H2O (3:2) were then concentrated (243 mg, 213 mg, 120 mg, 153 mg, respectively) and subjected to repeated preparative HPLC (YMC-ODS-A, 65:35:1 EtOH/H2O/1M CH3COONH4 to give 1 (3.3 mg), 2 (2.3 mg), 7 (15.0 mg), 10 (13.5 mg) and mixtures of 4 + 5 + 6 (12.8 mg) and of 8 + 9 (11.0 mg). The subfraction eluted with H2O was further extracted with BuOH, after which the butanol extract was concentrated (691 mg) and subjected to preparative HPLC (YMC-ODS-A, 30:70:1 EtOH/H2O/1M CH3COONH4 to give **3** (4.7 mg).
