Scheme 1.

Structures of 10 ceramide subfamilies included in this study. Designation in (*Parenthesis) is nomenclature of Motta et al.[29], expanded by Robson et al [30] and Masukawa et al [30]. In this system, the initial letter of the sphingoid base: S, dS, P, and H represent sphingosine, dihydrosphingosine, phytosphingosine, and 6-hydroxysphingosine, respectively; the fatty acid residues: N, A, O, and B represent nonhydroxylated acyl, a-hydroxyacyl, b-hydroxyacyl, and w-hydroxyacyl, respectively. As shown are ceramides with C18-LCB. More cermide structures please see Table 1.