Anthocyanin (also anthocyans ; from Greek: ????? (< i> anthos ) "flowers" and ??????? / ??????? kyaneos/kyanous " dark blue ") is a water-soluble vacuolar pigment which, depending on their pH, may appear red, purple, or blue. Food plants rich in anthocyanins include blueberries, raspberries, black rice, and black soybeans, among many others that are red, blue, purple, or black. Some autumn leaf colors come from anthocyanins.
Anthocyanins belonging to the parent class of molecules called flavonoids are synthesized via phenylpropanoid pathways. They occur in all the higher plant tissues, including leaves, stems, roots, flowers, and fruits. Anthocyanins are derived from anthocyanidins by adding sugar. They are odorless and astringent enough. Although approved for food and beverage colors in the EU, anthocyanins are not approved for use as food additives because they have not been verified safe when used as foodstuffs or supplements. There is no evidence of high quality anthocyanins that have any effect on biology or human disease.
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In flowers, the colors provided by the anthocyanin accumulation can attract a wide variety of animal pollinators, while in fruits, the same color can help in seed dispersion by attracting herbivorous animals to edible fruits containing red, blue, or purple. color.
Physiological Role
Anthocyanins may have a protective role in plants against extreme temperatures. Plant tomatoes protect against cold pressure with anthocyanins that fight against reactive oxygen species, leading to lower cell death rates in leaves.
Light absorption
The absorbance pattern responsible for the anthocyanin red color may complement the green chlorophyll in photosynthetic active tissue such as the young leaf Quercus coccifera . It can protect the leaves from attacks by herbivores that may be attracted by the green color.
Maps Anthocyanin
Occurrence of anthocyanin
Anthocyanins are found in cell vacuoles, mostly in flowers and fruits, but also in leaves, stems, and roots. In this section, they are found mainly in the outer cell layer such as the epidermis and peripheral mesophyll cells.
Most common in nature are glycosides from cyanidin, delphinidin, malvidine, pelargonidine, peonidin, and petunidine. Approximately 2% of all hydrocarbons fixed in photosynthesis are converted to flavonoids and their derivatives, such as anthocyanins. Not all terrestrial plants contain anthocyanins; in Caryophyllales (including cacti, beets, and spinach), they are replaced by betalain. Anthocyanins and betalains have never been found in the same plant.
Sometimes cultured deliberately for high amounts of anthocyanin, ornamental plants such as peppers may have an unusual culinary and aesthetic appeal.
In flower
Anthocyanins occur in many plant flowers, such as the famous blue flowers of several species and the Meconopsis cultivars.
In food
The anthocyanin-rich plant is a species of Vaccinium, such as blueberries, cranberries, and bilberries; Rubus berries, including black raspberries, red raspberries, and blackberries; blackcurrant, cherry, eggplant (aubergine) peeled, black rice, ube, Okinawa sweet potato, Concord wine, muscadine wine, red cabbage, and violet petals. Red peaches and apples contain anthocyanins. Anthocyanins are less abundant in bananas, asparagus, nuts, fennel, pear, and potatoes, and may be absent in certain green gooseberry cultivars.
The highest recorded amount appears to be specifically in the black soybean seed layer ( Glycine max L. Merr.) Contains about 2 g per 100 g, in purple corn and chaff seed, and in chokeberry peel and black (< i> Aronia melanocarpa L.) (see table). Because of the important differences in sample origin, preparation, and extraction methods that determine anthocyanin content, the values ​​presented in adjacent tables can not be compared directly.
Natural, traditional farming methods, and plant breeding have produced a variety of unusual plants containing anthocyanins, including blue or red meat potatoes and purple or red broccoli, cabbage, cauliflower, carrots, and corn. Garden tomatoes have been subjected to breeding programs using an introgression line from genetically modified organisms (but not putting them in the last purple tomatoes) to determine the genetic base of purple in wild species originally from Chile and the Galapagos Islands. Varieties known as "Indigo Rose" become commercially available for agricultural industries and home gardeners in 2012. Tomato investments with high anthocyanin content double their shelf life and inhibit the growth of post-harvest fungal pathogens, Botrytis cinerea
Some tomatoes have also been genetically modified by transcription factors from snapdragons to produce high levels of anthocyanins in fruits. Anthocyanins can also be found in mature natural olives, and some are responsible for the red and purple colors of some olives.
In the plant-based leaf
The content of anthocyanins in the leaves of colorful vegetable food such as purple corn, blueberry, or lingonberi, is about ten times higher than in edible seeds or fruit.
The spectrum of grape berry grape color can be analyzed to evaluate the amount of anthocyanin. Fruit maturity, quality, and harvest time can be evaluated based on spectrum analysis.
Autumn leaf color
The red, purple, and mixed combinations they are responsible for fall foliage are derived from anthocyanins. Unlike carotenoids, anthocyanins are absent in leaves throughout the growing season, but are produced actively, towards the end of summer. They develop in the late summer in the sap of leaf cells, resulting from the complex interactions of factors inside and outside the plant. Their formation depends on breaking down sugar in the presence of light because the phosphate levels in the leaves are reduced. The orange leaves in autumn are produced from a combination of anthocyanins and carotenoids.
Anthocyanins present in about 10% of tree species in temperate climates, although in certain areas such as New England, up to 70% of tree species can produce anthocyanins.
Color security
Anthocyanins approved for use as food colorings in the EU, Australia and New Zealand, have a coloring code E 163. In 2013, a panel of scientific experts for the European Food Safety Authority concluded that anthocyanins from various fruits and vegetables were insufficiently characterized by safety and toxicology to approve its use as a food additive. Expanding from the safe history of using red grape skin extract and blackcurrant extract for color foods produced in Europe, the panel concluded that the source of this extract was an exception to the verdict and was reasonably proven safe.
Anthocyanin extracts are not specifically listed among color additives approved for food in the United States; However, grape juice, red wine skin and plenty of fruit and vegetable juices, which are approved for use as a dye, are rich in natural anthocyanins. No anthocyanin source is included among approved dyes for drugs or cosmetics.
Human research
Although anthocyanins have been shown to have antibacterial properties in vitro , there is no evidence for antioxidant antioxidant effects in the body after the plants are consumed. Unlike controlled test tube conditions, the fate of anthocyanin in vivo shows that they are not well preserved (less than 5%), with most of what is absorbed as existing as a chemically modified metabolite quickly excreted. Increased blood antioxidant capacity seen after consumption of anthocyanin-rich foods may not be directly caused by anthocyanins in the diet, but vice versa, may result from elevated levels of uric acid derived from the metabolism of flavonoids in the diet. It is possible that the swallowed anthocyanic catabolite is reabsorbed in the gastrointestinal tract from which they can enter the blood for systemic distribution to have biological effects.
By 2017, no substantial clinical trials have shown that the anthocyanin diet lowers the risk of human disease.
Chemical anthocyanin
Flavylium cation derivation
Lihat artikel Anthocyanidins .
Glikosida anthocyanidin
Anthocyanins, anthocyanidins with the sugar group, are mostly 3-glucosides of anthocyanidins. Anthocyanins are divided into sugar-free anthocyanidin aglikon and anthocyanin glycosides. In 2003, more than 400 anthocyanins have been reported, while literature in early 2006, mentioned the number of more than 550 different anthocyanins. The difference in chemical structure that occurs in response to pH changes, is the reason why anthocyanin is often used as a pH indicator, since they change from red in acid to blue in base.
Stability
Anthocyanins are considered to have physiochemical degradation in vivo and in vitro . Structure, pH, temperature, light, oxygen, metal ions, intramolecular associations, and intermolecular relationships with other compounds (copigments, sugars, proteins, degradation products, etc.) are generally known to affect the color and stability of anthocyanins. The hydroxylation status of b-ring and pH has been shown to mediate the degradation of anthocyanins to phenolic acids and aldehyde constituents. Indeed, most of the digested anthocyanins tend to be degraded into phenolic acids and aldehydes in vivo , after consumption. This characteristic disrupts the scientific isolation of the special anthocyanin mechanisms in vivo .
pH
Anthocyanins are generally degraded at higher pH, however, some anthocyanins, such as petanins (petunidine 3- [6- O - (4- O - ( E ) - p -coumaroyl- O -? - L -rhamnopyranosyl) -? - D - glucopyranoside] -5- O -? - D -glucopyranoside), resistant to degradation at pH 8 and can be used effectively as food coloring.
Use as pH environment indicator
Anthocyanins may be used as pH indicators because their color changes with pH; they are red or pink in an acid solution (pH & lt; 7), purple in neutral solution (pH ~ 7), greenish yellow in base solution (pH & gt; 7), and colorless in a very alkaline solution, at where pigments are actually reduced.
Biosynthesis
- Anthocyanin pigments are assembled like all other flavonoids from two different chemical streams in the cell:
- One stream involves a shikimate path to produce amino acid phenylalanine, (see phenylpropanoid)
- The other stream produces three molecules of malonyl-CoA, unit C3 of unit C2 (acetyl-CoA),
- These streams converge and are combined together by chalcone synthase enzymes, which form intermediate chalcone compounds through the polyketide folding mechanism commonly found in plants,
- Chalcone is further isomerized by chalcone isomerase enzyme to the prototype of naringenin pigment,
- Naringenin is then oxidized by enzymes such as flavanone hydroxylase, flavonoid 3 'hydroxylase, and 3' 5'-hydroxylase flavonoids,
- The oxidation product is further reduced by the 4-reductase dihydroflavoneol enzyme into inappropriate colorless leucoanthocyanidins,
- Leucoanthocyanidins were once believed to be direct precursors of subsequent enzymes, dioxygenases known as anthocyanidin synthase, or, leucoanthocyanidin dioxigenase; Flavan-3-ols, leucoanthocyanidin reductase (LAR) products, have recently proven to be their true substrate,
- The resulting unstable anthocyanidin is subsequently coupled to sugar molecules by enzymes such as UDP-3-O-glucosyltransferase, to produce relatively stable late anthocyanins.
Thus, more than five enzymes are needed to synthesize these pigments, each working in concert. Even a small disturbance in one of these enzyme mechanisms by genetic or environmental factors, will stop the production of anthocyanin. While biological loads produce relatively high anthocyanins, plants benefit significantly from environmental adaptation, disease tolerance, and pest tolerance provided by anthocyanins.
In the pathway of anthocyanin biosynthesis, L-phenylalanine is converted to naringenin by phenylalanine amonialiase (PAL), cinnamic 4-hydroxylase (C4H), coagulase Coasarate 4-coumarate (4CL), chalcone synthase (CHS), and chalcone isomerase (CHI). Then, the subsequent path is catalyzed, resulting in the formation of complex aglikons and anthocyanins by composition by 3-hydroxylase (F3H) flavanon 3, glucoside: flavonoids glucosyltransferase (UFGT), and methyl transferase (MT). Among them, UFGT is divided into UF3GT and UF5GT, which are responsible for anthocyanin glucosylation to produce stable molecules.
In Arabidopsis thaliana , two glycosyltransferases, UGT79B1 and UGT84A2, are involved in the anthocyanin biosynthesis pathway. The UGT79B1 protein converts cyanidin 3-O-glucoside into cyanidine 3-O-xylosyl glucoside (1-> 2). UGT84A2 encodes a sinapic acid: UDP-glucosyltransferase.
Genetic analysis
The path of phenolic metabolism and enzymes can be studied by the average of gene transgenesis. The Arabidopsis control gene in the production of anthocyanin pigment 1 ( AtPAP1 ) can be expressed in other plant species.
Sensitive solar cells
Anthocyanins have been used in organic solar cells because of their ability to convert light energy into electrical energy. Many of the benefits of using dye-sensitive solar cells are compared to traditional pn silicon cells, including lower purity requirements and abundance of component ingredients, as well as the fact that they can be produced on a bending substrate, allowing them to roll-roll printing process.
Visual bookmarks
Anthocyanin fluoresce, enables a tool for plant cell research to allow the imaging of living cells without the requirement for other fluorophores. The production of anthocyanins can be engineered into genetically modified materials to enable their identification visually.
See also
- Phenolic compounds in wine
- p -Coumaroylated anthocyanin
References
Further reading
- Andersen, O.M. (2006). Flavonoids: Chemistry, Biochemistry, and Applications . Boca Raton FL: Press CRC. ISBN: 978-0-8493-2021-7.
- Gould, K.; Davies, K.; Winefield, C., eds. (2008). Anthocyanins: Biosynthesis, Functions, and Applications . Jumper. ISBN 978-0-387-77334-6.
External links
- Antosianin FAQ MadSci Network
Source of the article : Wikipedia
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