Sphingosine (d16:1), an unconventional sphingolipid, is synthesized through enzymatic reactions starting with the condensation of myristoyl-CoA and serine by serine palmitoyltransferase long-chain base subunit 3 (SPTLC3), which shows a preference for myristoyl-CoA. This compound is found in minute quantities in its free form in human plasma and as a component of various plasma sphingolipids, such as sphingosine-1-phosphate, ceramides, sphingomyelins, and in brain cerebrosides, albeit at lower concentrations than the more common d18:1 sphingoid base. Sphingosine (d16:1) acts as an inhibitor of PKC in mixed micelle assays and diminishes superoxide production triggered by phorbol 12-myristate 13-acetate in isolated human neutrophils, as well as inhibiting the growth of CHO cells with IC50 values of 1 and 3.2 µM, respectively. Additionally, the concentration of sphingolipids containing sphingosine (d16:1) in the plasma is linked to the dietary consumption of saturated fatty acids and protein among ethnic Chinese populations.
Sphingosine (d14:1) is a bioactive sphingolipid that has been found in B. mori (silkworm), P. clarkii (crayfish), and A. aurita (jellyfish) extracts. It increases the germination rate of N. rileyi, an entomopathogenic fungus, with an EC50 value of 10.2 nM. Sphingosine (d14:1) inhibits protein kinase C (PKC) in vitro (IC50 = 7.3 mol%) as well as superoxide generation induced by phorbol 12-myristate 13-acetate in neutrophils and reduces growth of CHO cells (IC50s = 19 and 8 μM, respectively).
HA-100 hydrochloride is a powerful protein kinase inhibitor, exhibiting IC50 values of 4 μM, 8 μM, 12 μM, and 240 μM for cGMP-dependent protein kinase (PKG), cAMP-dependent protein kinase (PKA), protein kinase C (PKC), and MLC-kinase, respectively. Additionally, HA-100 hydrochloride is utilized as a ROCK inhibitor.