Complex sentence: Closely related molecules were reported in the marine sponge "Dysidea arenaria", which were first given the name "arenastatins"; study of the structure-activity relationships between the two subgroups of molecules led to improved understanding of their cytotoxic effects.
Split into simpler sentences: Closely related molecules were reported in the marine sponge "Dysidea arenaria", which were first given the name "arenastatins". Nevertheless, study of the structure-activity relationships between the two subgroups of molecules led to improved understanding of their cytotoxic effects.