Cyclo(Pro-Pro) tasted bitter.Verpacamides A-D, a sequence of C11N5 diketopiperazines relating cyclo(Pro-Pro) to cyclo(Pro-Arg), from the marine sponge Axinella vaceleti is possible biogenetic precursors of pyrrole-2-aminoimidazole alkaloids.

3-Mercaptopropionic acid (3-Sulfanylpropanoic acid) is an intermediate in the metabolism of organosulfur in the natural environment and is commonly used in nanoparticles.

2,2'-Bipyridine is a unique bioactive natural product molecular scaffold commonly used in the core structure of many chelating ligands.