Neopetrosins A-D and Haliclorensin D, Indole- C -Mannopyranosides and a Diamine Alkaloid Isolated from the South China Sea Marine Sponge Neopetrosia chaliniformis .

Four new indole- C -mannopyranoside alkaloids, neopetrosins A-D ( 1 - 4 ), together with one new diamine alkaloid, haliclorensin D ( 6 ), were isolated from the marine sponge Neopetrosia chaliniformis collected off Xisha Island in the South China Sea. Their structures and absolute configurations were determined by spectroscopic analysis, single-crystal X-ray diffraction, calculated electronic circular dichroism (ECD), and DP4+ probability analyses. Compounds 1 , 2 , and 4 exhibited in vivo hepatoprotective activity in a zebrafish model at a concentration of 20 μM.