Fucoxanthin is a xanthophyll, with formula C₄₂H₅₈O₆. It is found as an

accessory pigment Accessory pigments are light-absorbing compounds, found in photosynthetic organisms, that work in conjunction with chlorophyll ''a''. They include other forms of this pigment, such as chlorophyll ''b'' in green algal and vascular ("higher") plan ...

in the

chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

s of

brown algae Brown algae (: alga) are a large group of multicellular algae comprising the class (biology), class Phaeophyceae. They include many seaweeds located in colder waters of the Northern Hemisphere. Brown algae are the major seaweeds of the temperate ...

and most other

heterokont The stramenopiles, also called heterokonts, are protists distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular surface, an ...

s, giving them a brown or olive-green color. Fucoxanthin absorbs light primarily in the blue-green to yellow-green part of the

visible spectrum The visible spectrum is the spectral band, band of the electromagnetic spectrum that is visual perception, visible to the human eye. Electromagnetic radiation in this range of wavelengths is called ''visible light'' (or simply light). The optica ...

, peaking at around 510–525 nm by various estimates and absorbing significantly in the range of 450 to 540 nm.

Function

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 ...

s are pigments produced by plants and algae and play a role in light harvesting as part of the

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 ...

process. Xanthophylls are a subset of carotenoids, identified by the fact that they are oxygenated either as hydroxyl groups or as epoxide bridges. This makes them more water soluble than carotenes such as beta-carotene. Fucoxanthin is a xanthophyll that contributes more than 10% of the estimated total production of carotenoids in nature. It is an accessory pigment found in the chloroplasts of many brown macroalgae, such as ''

Fucus ''Fucus'' is a genus of brown algae found in the intertidal zones of rocky seashores almost throughout the world. Description and life cycle The thallus is perennial with an irregular or disc-shaped holdfast or with haptera. The erect portion ...

'' , and the golden-brown unicellular microalgae, the

diatom A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...

s. It absorbs blue and green light at bandwidth 450–540 nm, imparting a brownish-olive color to algae. Fucoxanthin has a highly unique structure that contains both an epoxide bond and hydroxyl groups along with an allenic bond (two adjacent carbon-carbon double bonds) and a conjugated carbonyl group (carbon-oxygen double bond) in the polyene chain. All of these features provide fucoxanthin with powerful antioxidant activity. In macroalgal plastids, fucoxanthin acts like an antenna for light harvesting and energy transfer in the photosystem light harvesting complexes. In diatoms like '' Phaeodactylum tricornutum'', fucoxanthin is protein-bound along with chlorophyll to form a light harvesting protein complex. Fucoxanthin is the dominant carotenoid, responsible for up to 60% of the energy transfer to chlorophyll a in diatoms. When bound to protein, the absorption spectrum of fucoxanthin expands from 450–540 nm to 390–580 nm, a range that is useful in aquatic environments.

Sources

Fucoxanthin is present in brown seaweeds and

s and was first isolated from ''

'', '' Dictyota'', and '' Laminaria'' by Willstätter and Page in 1914. Seaweeds are commonly consumed in south-east Asia and certain countries in Europe, while diatoms are single-cell planktonic microalgae characterized by a golden-brown color, due to their high content of fucoxanthin. Generally, diatoms contain up to four times more fucoxanthin than seaweed, making diatoms a viable source for fucoxanthin industrially. Diatoms can be grown in controlled environments (such as photobioreactors).

Bioavailability

Limited studies of fucoxanthin in humans indicate low bioavailability.

References

{{Carotenoids Carotenoids Epoxides Brown algae Diatom biology Cumulated dienes

Function

Sources

Bioavailability

See also

References