Beta carotene is a type of carotenoid and pigment found naturally in carrots, beets, plants, algae and photosynthetic bacteria.

The name "beta-carotene" comes from the Greek "beta" and the Latin "carota" (carrot). It is a member of carotenes, which are unsaturated hydrocarbon pigments, with their structure composed of two linked retinyl groups. These are derived from isoprene, with their carbon skeleton consisting of 40 carbon atoms, usually in the form of eight isoprene units. The term carotene is used for several unsaturated hydrocarbon substances related to the formula C₄₀Hx,  synthesized by plants and cannot be produced by animals.

The synthesis of beta-carotene in plants occurs in plastids (including chloroplasts) and involves the action of several enzymes. Here is a simplified version of the process:

• The process begins with the formation of geranygeranyl pyrophosphate (GGPP), a 20-carbon molecule formed by the 5-carbon molecule isopentenyl pyrophosphate (IPP), produced through the pathway of mevalonate or methylleritritol phosphate.
• Two molecules of GGPP are then condensed by the enzyme GGPP synthase to form carbon 40 phytoene, the first carotenoid in the pathway.
• Phytoene is then desaturated and isomerized by phytoene desaturase and zeta-carotene isomerase to form lycopene.
• Lycopene is then cyclized by lycopene cyclase to form alpha-carotene or beta-carotene, depending on the specific enzyme cyclase involved.

The industrial synthesis of beta-carotene is carried out chemically or through the use of microorganisms.

• Chemical synthesis. This involves a series of reactions beginning with the condensation of two isoprene molecules to form a compound with ten carbon atoms. This compound undergoes a series of reactions, including isomerisation, cyclization and dehydrogenation, to form beta-carotene. This process requires precise control of reaction conditions and the use of various catalysts. The end product is often a mixture of different carotenoids that must be separated and purified.
• Microbial synthesis. Microbial synthesis of beta-carotene involves the use of microorganisms such as fungi, yeasts or genetically modified bacteria to produce beta-carotene. The microorganisms are grown in a controlled environment where they convert simple sugars into beta-carotene. The beta-carotene is then extracted and purified. This method is more environmentally friendly and sustainable than chemical synthesis, but can be more expensive and the yield may be lower.
• One of the most common industrial methods for producing beta-carotene is the fermentation of the fungus Blakeslea trispora. This fungus naturally produces beta-carotene and, through selection and optimisation of growth conditions, may be able to produce large quantities of beta-carotene.
• Another method is the use of genetically modified bacteria or yeasts. For example, the yeast Saccharomyces cerevisiae has been genetically modified to produce beta-carotene by introducing genes for the enzymes needed to convert acetyl-CoA, a common metabolite, into beta-carotene.

What it is for and where

Medical

Taken in the human body, it turns into vitamin A (retinol) and helps protect the eyes and the immune system in general, with particular reference to the skin and mucous membranes.

It has an antioxidant function and protects the body from harmful molecules called "free radicals" that damage cells by oxidizing them and producing premature aging.

Food

Ingredient included in the list of European food additives as colouring E160a (ii): beta carotene obtained from the fermentation of the fungus Blakeslea trispora, palm oil, carrots and algae.

Cosmetics

It is a restricted ingredient as IV/111 a Relevant Item in the Annexes of the European Cosmetics Regulation 1223/2009. Ingredient or substance at risk: 

Skin conditioning agent. It is the mainstay of topical skin treatment as it has the function of restoring, increasing or improving skin tolerance to external factors, including melanocyte tolerance. The most important function of the conditioning agent is to prevent skin dehydration, but the subject is rather complex and involves emollients and humectants that can be added in the formulation.

Safety

However, it should be noted that indiscriminate assumptions of vitamin A can be toxic, so it is useless to exaggerate as the body provides for superfluous quantities, but not excessive doses.

• Molecular Formula: C₄₀H₅₆
• Molecular Weight: 536.888 g/mol
• CAS: 7235-40-7
• EC Number: 230-636-6
• UNII: 01YAE03M7J
• PubChem Substance ID 329748926
• MDL number MFCD00001556
• Beilstein Registry Number 1917416

• beta Carotene
• Serlabo
• beta,beta-Carotene
• Natural Yellow 26
• Provitamin A
• Karotin
• Betacarotene
• Solatene
• Food orange 5
• Carotaben
• Lucaratin
• Provatene
• C.I. 75130
• CI 40800
• (all-E)-1,1'-(3,7,12,16-Tetramethyl-1,3,5,7,9,11,13,15,17-octadecanonaene-1,18-diyl)bis(2,6,6-trimethylcyclohexene)
• 2,2'-((1E,3E,5E,7E,9E,11E,13E,15E,17E)-3,7,12,16-tetramethyloctadeca-1,3,5,7,9,11,13,15,17-nonaene-1,18-diyl)bis(1,3,3-trimethylcyclohex-1-ene)
• 1,1'-(3,7,12,16-Tetramethyl-1,3,5,7,9,11,13,15,17-octadecanonaene-1,18-diyl)bis(2,6,6-trimethylcyclohexene), (all E)-
• Cyclohexene, 1,1'-(3,7,12,16-tetramethyl-1,3,5,7,9,11,13,15,17-octadecanonaene-1,18-diyl)bis(2,6,6-trimethyl-, (all-E)-
• 1,3,3-trimethyl-2-[(1E,3E,5E,7E,9E,11E,13E,15E,17E)-3,7,12,16-tetramethyl-18-(2,6,6-trimethylcyclohexen-1-yl)octadeca-1,3,5,7,9,11,13,15,17-nonaenyl]cyclohexene