Secondary Metabolites


A very intriguing aspect of J. funebris biology is the production of secondary metabolites. Secondary metabolites are derived from undigested remains of organisms that were fed on. The undigested remains are sequested and accumulated, and then can be used to biosynthesise secondary metabolites (Cimino et al. 1999, Fontana et al. 2001).    

The main secondary metabolite produced in dotted nudibranchs is an isoquinoline alkaloid called jorumycin (Fontana 2011). Jorumycin can be found in the mucus of dotted nudibranchs, suggesting that it plays a role in defence for the animal. The origin of this metabolite remains unclear, but is thought to be related to the sponge Xestospongia sp., an associated prey item of dotted nudibranchs (MeKee and Ireland 1987). Jorumycin was first isolated from the skin and mucus of J. funebris in 2000 (Fontana et al. 2000). This alkaloid has subsequently been shown to have cytotoxicity effects on various tumor cell lines, and compares well with drugs currently used to fight human cancers (Fontana et al. 2000, Fontana et al. 2001, Charupant et al. 2007).

A problem with jorumycin is that it degenerates very easily once extracted from an animal (Fontana et al. 2000). This instability is thought to be reducing the alkaloid’s effectiveness as a cytotoxic molecule, and the quest to continually refine the extraction process is on. Researchers are now using potassium cyanide (KCN) to stabilise jorumycin before isolation and extraction (Charupant et al. 2007). More sufficient quantities of unstable alkoloid with retention of bioactivity should be possible, and with it improved effectiveness against cancer cell lines (Charupant et al. 2007).