Is Ceramide 4 natural?

Ceramide 4 (retired name; now Ceramide AS) is synthesized by coupling a sphingoid base, commercially derived via yeast fermentation (tetraacetylphytosphingosine route), with a natural fatty acid via an amide bond. Some suppliers may use alternative synthetic sphingoid-base routes.

A skin-conditioning lipid that mimics ceramides naturally found in skin. It is produced by joining a fermentation-derived building block with a natural fatty acid, replicating the skin's own barrier lipids.

CosIng definition: Ceramide 4 (Retired) is the N-acylated sphingolipid having the erythro structure that conforms generally to the formula, where m has a value ranging from 13 to 27 in which the acyl moiety may be saturated or mono-unsataurated and n has a value ranging from 10 to 16. Ceramide 4 is similar to Ceramide 5, however, the acylating hydroxy acids are generally shorter in Ceramide 4 than in Ceramide 5. The INCI Name, Ceramide 4, originally developed in 1997, was designated with a retired status in 2014. For an interim period of time, trade name assignments formerly published with the INCI Name Ceramide 4 will be retained in the retired monograph, and also published with the new name assignment, Ceramide AS.