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α-Carotene is a precursor of vitamin A (Item No. 20241) that has been found in various fruits and vegetables. It inhibits proliferation of GOTO human neuroblastoma cells more potently than β-carotene (Item No. 16837) and halts the cell cycle at the G₀/G₁ phase concomitantly with a reduction in the mRNA expression of the protooncogene N-Myc. It is also more potent than β-carotene in mouse models of skin and lung carcinogenesis and decreases the number of hepatomas in mice with spontaneous liver carcinogenesis when administered in drinking water at a concentration of 0.05%. α-Carotene levels are increased in patients with coronary heart disease and are inversely correlated with the risk of estrogen receptor-negative breast cancer.

ChEBI: (6'R)-beta,epsilon-carotene is an alpha-carotene. It is an enantiomer of a (6'S)-beta,epsilon-carotene.

One of the primary isomers of carotene, enantiomerically pure form of metabolite in carotenoid biosynthesis, biosynthesis of plant secondary metabolites, biosynthesis of terpenoids and steroids and the biosynthesis of secondary metabolites.

Purify α-carotene by chromatography on columns of calcium hydroxide, alumina or magnesia. Crystallise it from CS2/MeOH, toluene/MeOH, diethyl ether/pet ether, or acetone/pet ether. Store it in the dark, under N2 or Ar at -20o. It gives a blue colour with max at 542nm when mixed with SbCl3 in CHCl3. [Karrer & Walker Helv Chim Acta 16 641 1933, Eugster et al. Helv Chim Acta 52 1729 1969, Eugster & Karrer Helv Chim Acta 38 610 1955, Strain J Biol Chem 105 523 1934, Beilstein 5 III 2457, 5 IV 2620.]