Catalysis of the reaction: an (11Z,14Z)-icosadienoyl-containing glycerolipid + 2 Fe(II)- + 2 H+ + O2 = an (8Z,11Z,14Z)-icosatrienoyl-containing glycerolipid + 2 Fe(III)- + 2 H2O or an (11Z,14Z,17Z)-icosatrienoyl-containing glycerolipid + 2 Fe(II)- + 2 H+ + O2 = an (8Z,11Z,14Z,17Z)-eicosatetraenoyl-containing glycerolipid + 2 Fe(III)- + 2 H2O.
Delta8-sphingolipid desaturase activity