Marine alkaloids as the chemical marker for the prey-predator relationship of the sponge Xestospongia sp. and the nudibranch Jorunna funebris

The dietary relationship study between marine sponge Xestospongia sp. and its nudibranch predators Jorunna funebris based on the discovery of isoquinolinequinones has long been studied. In this study, chemical investigation of the sponge Xestospongia sp. and nudibranch J. funebris from the South China Sea yielded a new marine alkaloid neopetroside C (1), together with nine known alkaloids (2-10). The chemical structures of all the compounds were elucidated by extensive spectroscopic analysis. Neopetroside C (1) featured a riboside of nicotinic acid with a rare alpha-N glycosildic linkage and an acyl residue of (Z)-2-methylbut-2-enoic acid attached to C-5 '. The plausible chemical ecology relationship between sponge Xestospongia sp. and its nudibranch predator J. funebris was proposed based on the biogenetic relationship of the common marine alkaloids. The observation of two structural fragments, (Z)-2-methylbut-2-enoyloxy and trigonelline groups in both sponge and nudibranch, indicated that nudibranch might uptake chemicals from sponge and then modify and transform them into chemical weapons to defend against predators.

Automated summary

This study investigated the chemical relationship between marine sponge Xestospongia sp. and its nudibranch predators Jorunna funebris, identifying a new marine alkaloid and proposing a chemical ecology relationship between the two organisms based on biogenetic similarities. The observation of common structural fragments in both sponge and nudibranch suggests that nudibranch may acquire and modify chemical compounds from the sponge to use as defense mechanisms against predators.