Fucoxanthin is a

xanthophyll Xanthophylls (originally phylloxanthins) are yellow pigments that occur widely in nature and form one of two major divisions of the carotenoid group; the other division is formed by the carotenes. The name is from Greek (, "yellow") and (, "lea ...

, with formula C₄₂H₅₈O₆. It is found as an accessory

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compou ...

in the

chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it i ...

s of

brown algae Brown algae (singular: alga), comprising the class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and p ...

and most other

heterokont Heterokonts are a group of protists (formally referred to as Heterokonta, Heterokontae or Heterokontophyta). The group is a major line of eukaryotes. Most are algae, ranging from the giant multicellular kelp to the unicellular diatoms, which a ...

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 portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called '' visible light'' or simply light. A typical human eye will respond to ...

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

Function

Carotenoids are pigments produced by plants and algae and play a role in light harvesting as part of the photosynthesis 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 spp''., and the golden-brown unicellular microalgae, the diatoms. 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 seaweed Brown algae (singular: alga), comprising the class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and p ...

s and

diatom A diatom ( Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising se ...

s and was first isolated from ''

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 o ...

'', ''

Dictyota ''Dictyota'' is a genus of brown seaweed in the family Dictyotaceae. Species are predominantly found in tropical and subtropical seas, and are known to contain numerous chemicals (diterpenes) which have potential medicinal value. As at the end of ...

'', and ''

Laminaria ''Laminaria'' is a genus of brown seaweed in the order Laminariales (kelp), comprising 31 species native to the north Atlantic and northern Pacific Oceans. This economically important genus is characterized by long, leathery laminae and relati ...

'' 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 4 times more Fucoxanthin than seaweed, making diatoms a viable source for fucoxanthin industrially. Diatoms can be grown in controlled environments (such as

photobioreactor Moss photobioreactor to cultivate Physcomitrella_patens.html"_;"title="mosses_like_''Physcomitrella_patens">mosses_like_''Physcomitrella_patens''_at_the_laboratory_scale A_photobioreactor_(PBR)_refers_to_any_cultivation_system_designed_for_growin ...

s). Brown seaweeds are mostly grown in the open sea, often exposed to metals and metalloids.

Potential therapeutic applications

Fucoxanthin has been shown to induce G1 cell-cycle arrest and

apoptosis Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes ( morphology) and death. These changes in ...

in various cancer cell lines and tumor growth in

animal model An animal model (short for animal disease model) is a living, non-human, often genetic-engineered animal used during the research and investigation of human disease, for the purpose of better understanding the disease process without the risk of ha ...

s of cancer. Fucoxanthin also reduces weight, improves blood

lipid profile A lipid profile or lipid panel is a panel of blood tests used to find abnormalities in lipids, such as cholesterol and triglycerides. The results of this test can identify certain genetic diseases and can determine approximate risks for cardiovas ...

s, and decreased

insulin resistance Insulin resistance (IR) is a pathological condition in which cells fail to respond normally to the hormone insulin. Insulin is a hormone that facilitates the transport of glucose from blood into cells, thereby reducing blood glucose (blood sugar ...

in animal models of

obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's ...

. In a human

clinical trial Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, diet ...

Fucoxanthin was shown to improve weight parameters in slightly obese Japanese subjects. Applications regarding diabetes are suggested by some research. In nonclinical assessments, fucoxanthin showed the capacity to notably inhibit the growth of Mycobacterium tuberculosis. Its mechanism of action was found to be correlated to the ability to inactivate two vital enzymes that play a significant role in mycobacterial cell wall biosynthesis namely UDP-galactopyranose mutase (UGM) and arylamine-N-acetyltransferase (TBNAT).

Bioavailability and safety

Limited studies of the

bioavailability In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its bioavailability is 100%. Ho ...

of fucoxanthin in humans suggest that it is low but might be improved through

formulation Formulation is a term used in various senses in various applications, both the material and the abstract or formal. Its fundamental meaning is the putting together of components in appropriate relationships or structures, according to a formul ...

. In rodents, fucoxanthin displays low toxicity when administered orally. While human safety data is limited, the FDA has acknowledged the use of Fucoxanthin as a dietary supplement and filled a New Dietary Ingredient (NDI) notification of Fucoxanthin derived from the microalgae ''

Phaeodactylum tricornutum ''Phaeodactylum tricornutum'' is a diatom. It is the only species in the genus ''Phaeodactylum''. Unlike other diatoms, ''P. tricornutum'' can exist in different morphotypes (fusiform, triradiate, and oval) and changes in cell shape can be stimul ...

''.

References

Other studies