Extraction and isolation of aaptamine

The marine sponge A. suberitoides was collected from the South China Sea in October 2012. The specimen was identified by Dr. Nicole J. de Voogd (National Museum of Natural History, Leiden, Netherlands). The voucher specimen (NO. XS-2012-30) was deposited at State Key Laboratory of Marine Drugs, Ocean University of China, Qingdao, Shandong, China. The isolation of aaptamine was described in our previous work (Gong et al. 2020). Briefly, the MeOH extract of A. suberitoides was subjected to column chromatography (CC) on silica gel using petroleum ether/acetone (from 100:1 to 1:1, v/v) and dichloromethane/methanol (from 20:1 to 0:1, v/v) as eluent to obtain nine fractions (Fr.1–Fr.9). Fr.6 was separated by silica gel CC and Sephadex LH-20 to yield Fr.6.6.1–Fr.6.6.3. Fr.6.6.2 was further purified by semi-preparative RP-HPLC (C18, MeOH/H₂O, 40:60, v/v, 1.5 mL/min) to yield compound aaptamine (62.5 mg) (Figure 1). The spectroscopic data was consistent with data previously reported for aaptamine.

Chemical structure of aaptamine.

Aaptamine: C₁₃H₁₂N₂O₂, yellow oil, ¹H NMR (500 MHz, DMSO-d₆) δ_H: 12.82 (1H, s, NH-1), 12.30 (1H, s, NH-4), 7.85 (1H, d, J = 6.8 Hz, H-2), 7.39 (1H, d, J = 6.6 Hz, H-5), 7.10 (1H, s, H-7), 6.86 (1H, d, J = 7.0 Hz, H-6), 6.39 (1H, d, J = 6.8 Hz, H-3), 3.97 (3H, s, OMe-8), 3.81 (3H, s, OMe-9); ¹³C NMR (125 MHz, DMSO-d₆); δ_C: 156.9 (C-8), 149.7 (C-3a), 141.9 (C-2), 133.7 (C-9a), 132.6 (C-6a), 131.4 (C-9), 139.9 (C-5), 116.3 (C-9b), 112.6 (C-6), 100.9 (C-7), 98.1 (C-3), 60.3 (OMe-9) and 56.5 (OMe-8).