A 1:1 mixture of
(4RS,4aSR)-4,4a-dihydro-3,4-methoxycarbonyl-9-(2-methoxy carbonylethyl)-4a,8,14,19-tetrametyl-18-vinyl-23H,25H-benzo[b]porphine-13-propionic acid and
(4RS,4aSR)-4,4a-dihydro-3,4-methoxycarbonyl-13-(2-methoxy carbonylethyl)-4a,8,14,19-tetrametyl-18-vinyl-23H,25H-benzo[b]porphine-9-propionic acid