1 An Update on the Biomedical Prospects of Marine-derived Small Molecules with Fascinating Atom and Stereochemical Diversity

In this chapter we discuss a selection of structurally diverse marine-derived small molecules (MDSMs) with potent and/or specific bioactivity and analyze their biomedical applications. The compounds included have been isolated either from marine macroorganisms, including sponges, ascidians (tunicates), bryozoans, and molluscs, or from microorganisms, such as bacteria and fungi. Our inquiry begins with a look back in time at a selection of important marine natural products, with particular focus on compounds in the clinical pipeline. The chapter continues with an analysis of a biosynthetically diverse assortment of 22 MDSMs and their structural elements of atom and stereochemical diversity. Entries have been divided into five biosynthetic classes: terpene, polyketide, alkaloid, depsipeptide, and polyketide–peptide. Enormous structural variety is represented by the marine natural products treated herein. The compounds selected can be considered to represent case examples of significant biomolecules with positivity and, in some cases, potent bioactivity accompanied by an unusual mechanism of action.