Catalysis of the reaction: an N-acyl-(4R)-4-hydroxysphinganine + 2 Fe(II)- + 2 H+ + O2 = a (4R,8E)-4-hydroxysphingenine ceramide + 2 Fe(III)- + 2 H2O or an N-acyl-(4R)-4-hydroxysphinganine + 2 Fe(II)- + 2 H+ + O2 = (4R,8Z)-4-hydroxysphing-8-enine ceramide + 2 Fe(III)- + 2 H2O. This results in the formation of a double bond between C8 and C9 of the long chain base of a sphingolipid.
sphingolipid delta-8 desaturase activity