Marrubiin is a natural product.

Tachyplesin I is a β-hairpin antimicrobial peptide that contains 17 amino acid residues. Tachyplesin I exhibits cytotoxic properties against various human tumor cell lines acting primarily by impairing the integrity of the outer cell membrane.

5-Hydroxytryptophan (5-HTP), also known as oxitriptan (INN), is a naturally occurring amino acid and chemical precursor for the treatment of depression.