Extraction and isolation. The air-dried red alga Symphyocladia latiuscula (4.3 kg) was extracted with 95% EtOH at room temperature (3 × 72 h). After the solvent was removed under reduced pressure at <40 °C, a dark residue (610 g) was obtained. The residue was partitioned between EtOAc and H2O, and the EtOAc-soluble partition (320 g) was chromatographed over silica gel, eluting with a gradient of 0–100% Me2CO/petroleum ether to yield 85 fractions (F1–F85) (see Supporting Information Scheme S1 for the fractionation scheme). Fraction F54 was further fractionated over Sephadex LH-20 using CHCl3–MeOH (2:1) to afford 21 fractions.