Chemically, crocin is the diester formed from the disaccharide gentiobiose and the 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.[4
Physiological effects on mammalian tissues and organisms
Crocin has been shown to be an antioxidant, and neural protective agent. The antioxidant behavior of crocin is related to the sugar moiety in crocin molecule which has a vital role in its chemical reactivity. It has also been shown to have an antiproliferative action against cancer cells in vitro. Limited evidence suggests possible antidepressant properties of crocin in mice and humans. One study reports aphrodisiac properties in male rats at very high doses.
^ Abdullaev, F. I. (2002), “Cancer Chemopreventive and Tumoricidal Properties of Saffron (Crocus sativus L.)”, Experimental Biology and Medicine, 227 (1), pp. 20–5, doi:10.1177/153537020222700104, PMID 11788779, archived from the original on 3 December 2008, retrieved 11 September 2011
^ Li, Na; Lin, Ge; Kwan, Yiu-Wa; Min, Zhi-Da (July 1999). “Simultaneous quantification of five major biologically active ingredients of saffron by high-performance liquid chromatography”. Journal of Chromatography A. 849 (2): 349–355. doi:10.1016/S0021-9673(99)00600-7. PMID 10457433.
^ Papandreou MA, Kanakis CD, Polissiou MG, Efthimiopoulos S, Cordopatis P, Margarity M, Lamari FN (2006). “Inhibitory activity on amyloid-beta aggregation and antioxidant properties of Crocus sativus stigmas extract and its crocin constituents”. J Agric Food Chem. 54 (23): 8762–8. doi:10.1021/jf061932a. PMID 17090119.
^ Jump up to:a b Akhtari K; Hassanzadeh K; Fakhraei B; Fakhraei N; Hassanzadeh H; Zarei S A (2013). “A density functional theory study of the reactivity descriptors and antioxidant behavior of Crocin”. Computational and Theoretical Chemistry. 1013: 123–129. doi:10.1016/j.comptc.2013.03.015.
^ Ochiai T, et al. (2006). “Protective effects of carotenoids from saffron on neuronal injury in vitro and in vivo”. Biochim Biophys Acta. 1770 (4): 578–584. doi:10.1016/j.bbagen.2006.11.012. PMID 17215084.
^ Zheng YQ, Liu JX, Wang JN, Xu L (2006). “Effects of crocin on reperfusion-induced oxidative/nitrative injury to cerebral microvessels after global cerebral ischemia”. Brain Res. 1138: 86–94. doi:10.1016/j.brainres.2006.12.064. PMID 17274961.
^ Escribano J, Alonso GL, Coca-Prados M, Fernandez JA (1996). “Crocin, safranal and picrocrocin from saffron (Crocus sativus L.) inhibit the growth of human cancer cells in vitro”. Cancer Letters. 100 (1–2): 22–30. doi:10.1016/0304-3835(95)04067-6. PMID 8620447.
^ Chryssanthi DG, Lamari FN, Iatrou G, Pylara A, Karamanos NK, Cordopatis P (2007). “Inhibition of breast cancer cell proliferation by style constituents of different Crocus species”. Anticancer Research. 27 (1A): 357–62. PMID 17352254.
^ Abdullaev Jafarova F, Caballero-Ortega H, Riverón-Negrete L, Pereda-Miranda R, Rivera-Luna R, Manuel Hernández J, Pérez-López I, Espinosa-Aguirre JJ (2002). “In vitro evaluation of the chemopreventive potential of saffron”. Rev. Invest. Clin. 54 (5): 430–6. PMID 12587418.
^ Hosseinzadeh, H; Jahanian, Z (2010). “Effect of Crocus sativus L. (saffron) stigma and its constituents, crocin and safranal, on morphine withdrawal syndrome in mice”. Phytotherapy Research. 24 (5): 726–30. doi:10.1002/ptr.3011. PMID 19827024.
^ Akhondzadeh, S; Fallah-Pour, H; Afkham, K; Jamshidi, AH; Khalighi-Cigaroudi, F (2004). “Comparison of Crocus sativus L. And imipramine in the treatment of mild to moderate depression: A pilot double-blind randomized trial ISRCTN45683816”. BMC Complementary and Alternative Medicine. 4: 12. doi:10.1186/1472-6882-4-12. PMC 517724. PMID 15341662.
^ Hosseinzadeh H, Ziaee T, Sadeghi A (June 2008). “The effect of saffron, Crocus sativus stigma, extract and its constituents, safranal and crocin on sexual behaviors in normal male rats”. Phytomedicine. 15 (6–7): 491–5. doi:10.1016/j.phymed.2007.09.020. PMID 17962007.