Dinoflagellate luciferin is a member of the class of bilenes that is 1,2,3,21-tetrahydro-5,7-ethanobilene-a-19(16H),5(2)-dione which is substituted at positions 2, 8, 13 and 18 by methyl groups and at positions 1, 3, 12 and 17 by carboxy, 2-carboxyethyl, ethyl and vinyl groups, respectively (the 1S,2S,3S diastereoisomer). It has a role as a luciferin. It is a member of bilenes, an oxo dicarboxylic acid, an amino dicarboxylic acid and a non-proteinogenic L-alpha-amino acid. It is a conjugate acid of a dinoflagellate luciferin(1-).