*3.1. General Methods*

Optical rotations were measured on a Perkin-Elmer 343 digital polarimeter (Perkin Elmer, Waltham, MA, USA). The 1H and 13C NMR spectra were recorded in CDCl3 using Bruker Avance III 500 (Bruker BioSpin GmbH, Rheinstetten, Germany) (500.13/125.77 MHz) or Avance III 700 Bruker FT-NMR (Bruker BioSpin GmbH, Rheinstetten, Germany) (700.13/176.04 MHz) spectrometers. HRESI and ESI mass spectra were recorded on an Agilent 6510 Q-TOF LC/MS mass spectrometer (Agilent Technologies, Santa Clara, CA, USA), and samples were dissolved in methanol (*c* 0.01 mg/mL). TLC was carried out on silica gel plates (CTX-1A, 5-17 μm, Sorbfil, Russia) and spots were visualized by spraying with aqueous 10% H2SO4 followed by heating. Column chromatography (CC) was performed on silica gel (KSK, 50−160 mesh, Sorbfil, Russia) and YMC ODS-A (12 nm, S-75 um, YMC Co., Ishikawa, Japan). HPLC was performed using an Agilent 1100 Series chromatograph with a differential refractometer (Agilent Technologies, Santa Clara, CA, USA). The reversed-phase columns (YMC-Pack ODS-A, YMC Co., Ishikawa, Japan, 10 mm × 250 mm, 5 μm and 4.6 mm × 250 mm, 5 μm) and normal-phase column (Ultrashere-Si, Beckman Instruments, Inc., Berkeley, CA, USA, 10 mm × 250 mm, 5 μm) were used for HPLC. Yields are based on dry weight of the sponge.
