Ceramides and steroids of the zoanthides Palythoa caribaeorum and Protopalythoa variabilis

The chemical investigation of the marine species Palythoa caribaeorum and Protopalythoa variabilis, both collected at Paracurú beach, state of Ceará – Brazil, resulted in the isolation of tetracyclic sterols possessing the ergostan skeleton: 24(R)-ergost-5-en-3β-ol; 5α,8α-epidioxy-24(R)-ergost-6-en-3β-ol; 24(R)-ergost-5-en-3β,7α-diol; 24(R)-7α-hydroperoxy-ergost-5-en-3β-ol; 24(R)-ergost-7-en-3β,5α,6β-triol and 24(R)-B-norergostan-3β-5β-diol-6β-carboxylic acid. In addition, four ceramides: N-(2S,3R,4E,8E,1,3-dihydroxy-4,8-octadecadienyl)hexadecanamide; N-(2S,3R,4E,1,3-dihydroxy-4-octadecenyl)hexadecanamide (N-[2S,3R,4E,8E,1-(2”-methylamino-ethanosulfonyl)-3-hydroxy-4,8-octadecaenyl]hexadecanamide and N-[2S,3R,4E,1-(2”-methylaminoethano-sulfonyl)-3-hydroxy-4-octadecenyl]hexadeca-namide, were also isolated. The cytotoxic and antifungal properties of all ceramides were evaluated, nevertheless none of them showed any activity. The structures of the isolated compounds were elucidated using spectrometric techniques, such as: GC/MS, HRESIMS, IR and NMR (¹H, ¹³C and ¹⁵N) through 1D and 2D pulse sequences and, whenever the case, comparison with literature data