Marine natural products are naturally occurring chemical substances isolated from marine organisms, marine-associated microorganisms, or biological material collected from marine and intertidal environments. They comprise structurally characterized primary and, more commonly, specialized (secondary) metabolites produced by, accumulated in, or biotransformed within marine biological systems ^[1][2]. The term encompasses compounds associated with marine bacteria, archaea, fungi, microalgae and macroalgae, as well as marine invertebrates and other marine eukaryotes; in host-associated specimens, the immediate biosynthetic producer may be a symbiotic or otherwise associated microorganism rather than the macroscopic host ^[1]. Marine natural products are defined principally by their natural marine source and biosynthetic origin, rather than by a single chemical scaffold, molecular target, or biological activity. Accordingly, the category includes chemically diverse metabolite classes, such as terpenoids, polyketides, non-ribosomal peptides, alkaloids, and lipids, including members for which bioactivity has been experimentally characterized ^[1][2]. It excludes fully synthetic compounds and substances of non-marine origin merely detected or used in marine contexts.