ζ-Carotene (''zeta''-carotene) is a

carotenoid Carotenoids () are yellow, orange, and red organic pigments that are produced by plants and algae, as well as several bacteria, archaea, and fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips, corn, tomatoes, cana ...

. It is different from α-carotene and β-carotene because it is acyclic. ζ-Carotene is similar in structure to

lycopene Lycopene is an organic compound classified as a tetraterpene and a carotene. Lycopene (from the Neo-Latin '' Lycopersicon'', the name of a former tomato genus) is a bright red carotenoid hydrocarbon found in tomatoes and other red fruits and ve ...

, but has an additional 4

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

atoms. ζ-carotene can be used as an intermediate in forming β-carotene. A

dehydrogenation In chemistry, dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule. It is the reverse of hydrogenation. Dehydrogenation is important, both as a useful reaction and a serious problem. At ...

reaction converts ζ-carotene into lycopene, which then can be transformed into β-carotene through the action of lycopene beta-cyclase. ζ-Carotene is a natural product found in ''

Lonicera japonica ''Lonicera japonica'', known as Japanese honeysuckle and golden-and-silver honeysuckle, is a species of honeysuckle native to East Asia, including many parts of China. It is often grown as an ornamental plant, but has become an invasive species i ...

'' and ''

Rhodospirillum rubrum ''Rhodospirillum rubrum'' (''R. rubrum'') is a Gram-negative, pink-coloured bacterium, with a size of 0.8-1 μm. It is a facultative anaerobe with a large set of possible metabolisms depending on the conditions of its environment. It's capable ...

''.

Biosynthesis and role

ζ-carotene is formed in plants as an intermediate in the carotenoid

biosynthetic pathway In biochemistry, a metabolic pathway is a linked series of chemical reactions occurring within a cell. The reactants, products, and intermediates of an enzymatic reaction are known as metabolites, which are modified by a sequence of chemical re ...

. It is produced through sequential desaturation of

phytoene Phytoene () is a 40-carbon intermediate in the biosynthesis of carotenoids. The synthesis of phytoene is the first committed step in the synthesis of carotenoids in plants. Phytoene is produced from two molecules of geranylgeranyl pyrophosphate ( ...

by phytoene desaturase and ζ-carotene desaturase enzymes ζ-Carotene occupies a key position in the pathway, serving as a precursor to

, which is further converted into essential

carotenoids Carotenoids () are yellow, orange, and red organic compound, organic pigments that are produced by plants and algae, as well as several bacteria, archaea, and Fungus, fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips ...

such as β-carotene. These downstream carotenoids are vital for plant functions, including

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

photoprotection Photoprotection is the biochemical process that helps organisms cope with molecular damage caused by sunlight. Plants and other oxygenic phototrophs have developed a suite of photoprotective mechanisms to prevent photoinhibition and oxidative str ...

, and hormone synthesis. Thus, ζ-carotene plays an important regulatory and biosynthetic role in plant metabolism.

Research and applications

Zeta-carotene has gained attention in plant

biotechnology Biotechnology is a multidisciplinary field that involves the integration of natural sciences and Engineering Science, engineering sciences in order to achieve the application of organisms and parts thereof for products and services. Specialists ...

due to its role as an intermediate in carotenoid biosynthesis. Advances in synthetic biology have enabled targeted manipulation of carotenoid pathways, with zeta-carotene serving as a key point for regulating the production of downstream compounds such as lycopene and β-carotene. These strategies aim to optimize carotenoid composition in plants to enhance

nutritional value Nutritional value or nutritive value as part of food quality is the measure of a well-balanced ratio of the essential nutrients carbohydrates, fat, protein, minerals, and vitamins in items of food or diet concerning the nutrient requirements of ...

, improve stress tolerance, and increase

pigment A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...

content for industrial uses. As such, zeta-carotene has become an important focus in efforts to engineer plant metabolism for agricultural and commercial benefits.

References

Carotenoids {{Biochem-stub