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

Four new indole--mannopyranoside alkaloids, neopetrosins A-D (-), together with one new diamine alkaloid, haliclorensin D (), were isolated from the marine sponge 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 , , and exhibited in vivo hepatoprotective activity in a zebrafish model at a concentration of 20 μM.