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).
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.
20-Deoxyingenol 3-angelate and ingenol 20-acetate 3-angelate are known as promoters of tumors of mouse skin. 20-Deoxyingenol 3-angelate can induce significant platelet aggregation accompanied by induction of phosphorylation of PKC substrates in platelets,