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

UNLABELLED

The dietary relationship study between marine sponge sp. and its nudibranch predators based on the discovery of isoquinolinequinones has long been studied. In this study, chemical investigation of the sponge sp. and nudibranch from the South China Sea yielded a new marine alkaloid neopetroside C (), together with nine known alkaloids (-). The chemical structures of all the compounds were elucidated by extensive spectroscopic analysis. Neopetroside C () featured a riboside of nicotinic acid with a rare - glycosildic linkage and an acyl residue of ()-2-methylbut-2-enoic acid attached to C-5'. The plausible chemical ecology relationship between sponge sp. and its nudibranch predator was proposed based on the biogenetic relationship of the common marine alkaloids. The observation of two structural fragments, ()-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.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s42995-021-00096-w.