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A water-soluble B fraction was found in the 1920s to contain a yellow, fluorescent growth factor called Riboflavin in England and vitamin G in the United States.
In the early 1930s, several groups found the coenzyme forms of Riboflavin 50-phosphate (flavin mononucleotide) and the further conjugate with adenylic acid (flavin adenine dinucleotide).
Riboflavin in which the hydroxy group at position 5 is substituted by a 7,8-dimethyl-2,4-dioxo-3,4-dihydrobenzo[g]pteridin-10(2H)-yl moiety.
CAS: 83-88-5
MF: C17H20N4O6
MW: 376.36
EINECS: 201-507-1
Synonyms
vitasanb2;xypentyl)-;E 101;Riboflavin (1.07609);Riboflavin Vitamin B2;Vitamin B2 (Riboflavine);RIBOFLAVIN DC GRADE;RIBOFLAVIN USP (VITAMIN B-2)
Riboflavin is a nutritional factor found in milk, eggs, malted barley, liver, kidney, heart, and leafy vege ables, but the richest natural source is yeast.
The free form occurs only in the retina of the eye, in whey, and in urine; its principal forms in tissues and cells are as flavin mononucleotide and flavin-adenine dinucleotide.
The conflicting results were eventually found to be due,in part, to deficiencies in study animals not just of Riboflavin, but also vitamin B3 (niacin), the cause of human forms of pellagra,and/or vitamin B6 (pyridoxine), another cause of dermatitis.
Likewise, treatments with vitamin B2 were inconsistentbecause the early sources of this vitamin contained otherB vitamins.
Riboflavin was eventually isolated from eggwhites in 1933 and produced synthetically in 1935.
The name riboflavine was officially accepted in 1960; althoughthe term was in common use before then.
In 1966, IUPAC changed Riboflavin to riboflavin, which is in common use today.
Riboflavin is synthesized by all green plants and by mostbacteria and fungi.
Therefore, riboflavin is found, at least insmall amounts, in most foods.
Foods that are naturally highin riboflavin include milk and other dairy products, meat,eggs, fatty fish, and dark green vegetables.
Chemically, riboflavin is an N-glycoside of flavin, alsoknown as lumichrome, and the sugar, ribitol.
Flavin is derived from the Latin word flavus for “yellow”because of the yellow color of its crystals and yellow fluorescenceunder UV light.
Riboflavin is heat stable but easilydegraded by light.
Riboflavin's systematic names are 7,8-dimethyl-10-ribitylisoalloxazine and 7,8-dimethyl-10-(D-ribo-2,3,4,5-tetrahydroxypentyl)isoalloxazine.
Riboflavin, also known as vitamin B2, is a vitamin found in food and sold as a dietary supplement.
Riboflavin is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide.
These coenzymes are involved in energy metabolism, cellular respiration, and antibody production, as well as normal growth and development.
The coenzymes are also required for the metabolism of niacin, vitamin B6, and folate. Riboflavin is prescribed to treat corneal thinning, and taken orally, may reduce the incidence of migraine headaches in adults.
Riboflavin deficiency is rare and is usually accompanied by deficiencies of other vitamins and nutrients.
Riboflavin may be prevented or treated by oral supplements or by injections.
As a water-soluble vitamin, any riboflavin consumed in excess of nutritional requirements is not stored; Riboflavin is either not absorbed or is absorbed and quickly excreted in urine, causing the urine to have a bright yellow tint.
Natural sources of riboflavin include meat, fish and fowl, eggs, dairy products, green vegetables, mushrooms, and almonds.
Some countries require its addition to grains.
In its purified, solid form, Riboflavin is a water-soluble yellow-orange crystalline powder.
In addition to its function as a vitamin, Riboflavin is used as a food coloring agent.
Biosynthesis takes place in bacteria, fungi and plants, but not animals.
Industrial synthesis of riboflavin was initially achieved using a chemical process, but current commercial manufacturing relies on fermentation methods using strains of fungi and genetically modified bacteria.
In 2023, riboflavin was the 294th most commonly prescribed medication in the United States, with more than 400,000 prescriptions.
Riboflavin, also known as vitamin B2, is a water-soluble vitamin and is one of the B vitamins.
Unlike folate and vitamin B6, which occur in several chemically related forms known as vitamers, riboflavin is only one chemical compound.
Riboflavin is a starting compound in the synthesis of the coenzymes flavin mononucleotide (FMN, also known as riboflavin-5'-phosphate) and flavin adenine dinucleotide (FAD).
FAD is the more abundant form of flavin, reported to bind to 75% of the number of flavin-dependent protein encoded genes in the all-species genome (the flavoproteome) and serves as a co-enzyme for 84% of human-encoded flavoproteins.
In its purified, solid form, riboflavin is a yellow-orange crystalline powder with a slight odor and bitter taste.
Riboflavin is soluble in polar solvents, such as water and aqueous sodium chloride solutions, and slightly soluble in alcohols.
Riboflavin is not soluble in non-polar or weakly polar organic solvents such as chloroform, benzene or acetone.
In solution or during dry storage as a powder, riboflavin is heat stable if not exposed to light.
When heated to decompose, it releases toxic fumes containing nitric oxide.
Vitamin B2, or riboflavin, is the key building block for its co-enzymatic forms Flavin adenine dinucleotide (FAD) and Flavin mononucleotide (FMN).
These serve as electron carriers in various redox reactions in energy production and metabolic pathways, including carbohydrate, lipid, and protein metabolism; the electron transport chain and various antioxidant functions.
Riboflavin Chemical Properties
Melting point: 290 °C (dec.)(lit.)
alpha: -135 º (c=5, 0.05 M NaOH)
Boiling point: 504.93°C (rough estimate)
density: 1.2112 (rough estimate)
bulk density: 100kg/m3
refractive index: -135 ° (C=0.5, JP Method)
Fp: 9℃
storage temp.: 2-8°C
solubility: Very slightly soluble in water, practically insoluble in ethanol (96 per cent). Solutions deteriorate on exposure to light, especially in the presence of alkali. It shows polymorphism (5.9).
form: Powder
pka: 1.7(at 25℃)
color: Yellow to orange
PH: 5.5-7.2 (0.07g/l, H2O, 20°C)
Odor: Slight odour
PH Range: 6
biological source: synthetic
Optical Rotation: [α]/D -135.0 to -155.0°, c =0.5% in 0.05 M NaOH (dry basis)
Water Solubility: 0.07 g/L (20 ºC)
Sensitive: Light Sensitive
Merck: 14,8200
BRN: 97825
BCS Class: 1
Stability: Stable, but light-sensitive. Incompatible with strong oxidizing agents, reducing agents, bases, calcium, metallic salts. May be moisture sensitive.
Cosmetics Ingredients Functions SKIN CONDITIONING - MISCELLANEOUS
COLORANT
InChI: 1S/C17H20N4O6/c1-7-3-9-10(4-8(7)2)21(5-11(23)14(25)12(24)6-22)15-13(18-9)16(26)20-17(27)19-15/h3-4,11-12,14,22-25H,5-6H2,1-2H3,(H,20,26,27)/t11-,12+,14-/m0/s1
InChIKey: AUNGANRZJHBGPY-SCRDCRAPSA-N
LogP: -2.009 (est)
CAS DataBase Reference: 83-88-5(CAS DataBase Reference)
NIST Chemistry Reference: Riboflavine(83-88-5)
EPA Substance Registry System: Riboflavin (83-88-5)
VITAMIN B2 (Riboflavin).
Some earlier designations for this substance included vitamin G, lactoflavin, hepatoflavin, ovoflavin, verdoflavin.
The chemical name is 6,7-dimethyl-9-d-l’ribityl isolloxazine.
Riboflavin is a complex pigment with a green fluorescence.
Physical properties
Riboflavin is moderately soluble in water (10–13 mg/dl) and ethanol but insoluble in ether, chloroform, and acetone.
Riboflavin is soluble but unstable under alkaline conditions.
The catalytic functions of riboflavin are carried out primarily at positions N-1, N-5, and C-4 of the isoalloxazine nucleus.
In addition, the methyl group at C-8 participates in covalent bonding with enzyme proteins.
The flavin coenzymes are highly versatile redox cofactors because they can participate in either one- or two electron redox reactions
Riboflavin antagonists include analogs of the isoalloxazine ring (e.g., diethylri boflavin, dichlororiboflavin) and the ribityl side chain (e.g., d-araboflavin, d-galactoflavin, 7-ethylriboflavin).
Uses
Vitamin B2 (riboflavin) is produced by yeast from glucose, urea, and mineral salts in an aerobic fermentation.
Nutritional factor found in milk, eggs, malted barley, liver, kidney, heart, leafy vegetables.
Richest natural source is yeast.
Minute amounts present in all plant and animal cells.
Vitamin (enzyme cofactor).
Riboflavin (Vitamin B2) is used in skin care preparations as an emollient.
Riboflavin can be found in sun care products as a suntan enhancer.
Medicinally, Riboflavin is used for the treatment of skin lesions.
Riboflavin is the water-soluble vitamin b2 required for healthy skin and the building and maintaining of body tissues.
Riboflavin is a yellow to orange-yellow crystalline powder.
Riboflavin acts as a coenzyme and carrier of hydrogen.
Riboflavin is stable to heat but may dissolve and be lost in cooking water.
Riboflavin is relatively stable to storage. sources include leafy vegetables, cheese, eggs, and milk.
Uses
Treatment of corneal thinning
Keratoconus is the most common form of corneal ectasia, a progressive thinning of the cornea.
The condition is treated by corneal collagen cross-linking, which increases corneal stiffness.
Cross-linking is achieved by applying a topical riboflavin solution to the cornea, which is then exposed to ultraviolet A light.
Migraine prevention
In its 2012 guidelines, the American Academy of Neurology stated that high-dose riboflavin (400 mg) is "probably effective and should be considered for migraine prevention," a recommendation also provided by the UK National Migraine Centre.
A 2017 review reported that daily riboflavin taken at 400 mg per day for at least three months may reduce the frequency of migraine headaches in adults.
Research on high-dose riboflavin for migraine prevention or treatment in children and adolescents is inconclusive, and so supplements are not recommended.
Food coloring
Riboflavin is used as a food coloring (yellow-orange crystalline powder), and is designated with the E number, E101, in Europe for use as a food additive.
Clinical Use
Severe riboflavin deficiency is known as ariboflavinosis, andtreatment or prevention of this condition is the only provenuse of riboflavin.
Ariboflavinosis is most commonly associatedwith multiple vitamin deficiency as a result of alcoholismin developed countries.
Because of the large numberof enzymes requiring riboflavin as a coenzyme, deficienciescan lead to a wide range of abnormalities.
In adults seborrheicdermatitis, photophobia, peripheral neuropathy, anemia, andoropharyngeal changes including angular stomatitis, glossitis,and cheilosis, are often the first signs of riboflavin deficiency.
In children, cessation of growth can also occur.
As the deficiencyprogresses, more severe pathologies develop untildeath ensues.
Riboflavin deficiency may also produce teratogeniceffects and alter iron handling leading to anemia.
Manufacturing Process
100 g of riboflavin and 3 of potassium carbonate are suspended in 500 cc of the aqueous formaldehyde solution and the mixture is stirred at 30°C for 8 hours.
At the end of this period, 5 cc of glacial acetic acid and 1 liter of methanol are added, with stirring.
The solution is freed from undissolved material by filtration and the clear solution is poured slowly at about 20°C to 22°C with vigorous stirring into 8 liters of anhydrous acetone.
The resultant precipitate is filtered off, washed repeatedly with anhydrous acetone and with ether, and then dried at room temperature and with vacuum.
The resultant dried powder is dissolved in hot water at 95°C to give an aqueous solution of 20% by weight.
This solution is kept in the dark at room temperature for 3 to 4 weeks, after which time a large amount of material crystallizes out of the solution.
This crystallized material is removed by filtration and recrystallized from hot water.
A small amount of dark red insoluble material is filtered from the hot solution.
This recrystallization step is repeated four times.
The resultant end product is monomethylol riboflavin, which crystallized in small orange clusters.
Riboflavin has a melting point of 232°C to 234°C with decomposition, and it becomes dark when heated above 225°C.
Purification Methods
Riboflavin crystallises from H2O as a yellow-orange powder in three different forms with differing amounts of H2O.
Riboflavin melts if placed in an oil bath at 250o, but decomposes at 280o if heated at a rate of 5o/minute.
Riboflavin is also purified by crystallisation from 2M acetic acid, then extracted with CHCl3 to remove lumichrome impurity.
Riboflavin's solubility in H2O is 1g in 3-15L depending on the crystal structure.
Riboflavin's solubility in EtOH at 25o is 4.5mg in 100mL.
Store Riboflavin in the dark because it is decomposed to lumichrome by UV light.
Biochem/physiol Actions
Riboflavin serves as a precursor for the active enzyme cofactors riboflavin 5′-monophosphate (also called flavin mononucleotide or FMN) and flavin adenine dinucleotide (FAD).
Riboflavin deficiency in the diet results in a well-defined syndrome known as ariboflavinosis, Riboflavin exhibits protective effects against tumor development and cardiovascular disease.
Riboflavin's deficiency often affects metabolism involving redox reactions.
Riboflavin is found essential for iron absorption, gastrointestinal development, neurogenesis, corneal vascularization and corneal opacity.
