The immunomodulatory activity of extract from Styela clava was studied systematically based on activity tracking in vitro in order to find out novel-structured secondary metabolite. The proliferation rates of mouse splenic lymphocytes and peritoneal macrophages were used as screening index, as well as NO release promoting activities. The crude extract (CE) and its different polar fractions from S. clava all exhibited proliferative activity of splenolymphocytes and mouse macrophages, as well as NO release promoting activities, among which petroleum ether fraction (PE) showed the strongest effect. The antioxidant experiment in vitro showed that CE demonstrated antioxidant ability in 1,1-diphenyl-2-picrylhydrazyl (DPPH) system and the beta carotene-linoleic acid system; the activity of ethyl acetate fraction (ET) was much stronger than that of the others. Further isolated by silica gel column chromatography, ET was classified into seven sub-components (E1∼E7) listed in the order of activity as E5 > E6 > E4 > E3 > E7 > E2 > E1. Five compounds were separated as (1) cholesteric-7-en-3 -ol, (2) cholesteric-4-en-3 ,6 -diol, (3) cholesterol, (4) batilol, and (5) ceramide, among which (1), (2), and (4) were isolated for the first time from S. clava
