Myriocin, also known as antibiotic ISP-1 and thermozymocidin, is a non-proteinogenic amino acid derived from the entomopathogenic fungus, Isaria sinclairii.

[1] Myriocin is a very potent inhibitor of serine palmitoyltransferase, the first step in sphingosine biosynthesis.

[1] Due to this property, it is used in biochemical research as a tool for depleting cells of sphingolipids.

Myriocin was shown to inhibit the proliferation of an IL-2-dependent mouse cytotoxic T cell line.

[citation needed] The multiple sclerosis drug fingolimod was derived from myriocin by using structure–activity relationship studies to determine the parts of the molecule important to its activity.