Beta-carboline alkaloids derived from the ascidian Synoicum sp.

Six beta-carboline alkaloids (1-6) of the eudistomin Y class were isolated from the Korean ascidian Synoicum sp. These compounds were chemically converted to a known compound, eudistomin Y-1 (7) and six new derivatives, designated eudistomins Y-8-Y-13 (8-13). Several of these natural and synthetic compounds exhibited moderate to significant antimicrobial activity, weak cytotoxic activity, and inhibitory activities toward sortase A, isocitrate lyase, and Na+/K+-ATPase. Structure-activity relationships were also deduced. (C) 2012 Elsevier Ltd. All rights reserved.