Bixin[1]
IUPAC name	(2E,4E,6E,8E,10E,12E,14E,16Z,18E)-20-methoxy-4,8,13,17-tetramethyl-20-oxoicosa-2,4,6,8,10,12,14,16,18-nonaenoic acid
Other names	cis-Bixin; α-Bixin; 9-cis-6,6'-Diapo-ψ,ψ-carotenedioic acid, 6-methyl ester
Identifiers
CAS number	6983-79-5, 39937-23-0 (trans-Bixin)
PubChem	5281226
SMILES	O=C(O)\C=C\C(=C\C=C\C(=C\C=C\C=C(\C=C\C=C(/C=C/C(=O)OC)C)C)C)C
InChI	1/C25H30O4/c1-20(12-8-14-22(3)16-18-24(26)27)10-6-7-11-21(2)13-9-15-23(4)17-19-25(28)29-5/h6-19H,1-5H3,(H,26,27)/b7-6+,12-8+,13-9+,18-16+,19-17+,20-10+,21-11+,22-14+,23-15-
InChI key	RAFGELQLHMBRHD-SLEZCNMEBU
ChemSpider ID	4444638
Properties
Molecular formula	C25H30O4
Molar mass	394.5 g mol−1
Appearance	Orange crystals
Solubility in water	Insoluble
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Bixin is an apocarotenoid found in annatto, a natural food coloring obtained from the seeds of the achiote tree (Bixa orellana). Annatto seeds contain about 5% pigments, which consist of 70-80% bixin.^[2]

Bixin is chemically unstable when isolated and converts via isomerization into trans-bixin (β-bixin), the double-bond isomer.^[1]

Bixin is soluble in fats but insoluble in water. Upon exposure to alkali, the methyl ester is hydrolyzed to produce the dicarboxylic acid norbixin, a water-soluble derivative.

Chemical structure of trans-bixin

Chemical structure of norbixin

[edit] References