[2-[(7Z,9Z,11Z,13Z,15Z)-octadeca-7,9,11,13,15-pentaenoyl]oxy-3-[(9Z,11Z,13Z,15Z)-octadeca-9,11,13,15-tetraenoyl]oxypropyl] (9Z,11Z,13Z)-henicosa-9,11,13-trienoate