Crocin

Crocin is a carotenoid chemical compound that is found in the flowers of crocus, gardenia and Buddleja (butterfly bush) Crocin is the chemical primarily responsible for the color of saffron. Chemically, crocin is the diester formed from the disaccharide gentiobiose and the branched-chain dicarboxylic acid crocetin. When isolated as a pure chemical compound, it has a deep red color and forms crystals with a melting point of 186 °C. When dissolved in water, it forms an orange solution. The term crocins may also refer to members of a series of related hydrophilic carotenoids that are either monoglycosyl or diglycosyl polyene esters of crocetin. The crocin underlying saffron's aroma is α-crocin (a carotenoid pigment that may compose more than 10% of dry saffron's mass): trans-crocetin di-(β-D-gentiobiosyl) ester; it bears the systematic (IUPAC) name 8,8-diapo-8,8-carotenoic acid. The major active component of saffron is the yellow pigment crocin 2 (three other derivatives with different glycosylations are known) containing a gentiobiose (disaccharide) group at each end of the molecule. The five major biologically active components of saffron, namely the four crocins and crocetin, can be measured with HPLC-UV.