Riboflavin

Riboflavin

Systematic name	Riboflavin
Chemical formula	C₁₇H₂₀N₄O₆
Molecular mass	376.369 g/mol
Density	? g/cm³
Melting point	290 °C (dec.)
CAS number	[83-88-5]
SMILES
Disclaimer and references

Riboflavin (E101), also known as vitamin B₂ or vitamin G, is an easily absorbed micronutrient with a key role in maintaining health in animals. Like the other B vitamins, it supports energy production by aiding in the metabolising of fats, carbohydrates, and proteins. Vitamin B₂ is also required for red blood cell formation and respiration, antibody production, and for regulating human growth and reproduction. It is essential for healthy skin, nails, hair growth and general good health, including regulating thyroid activity. Riboflavin also helps in the prevention or treatment of many types of eye disorders, including some cases of cataracts. It may assist bloodshot, itching or burning eyes and abnormal sensitivity to light.

Milk, cheese, leafy green vegetables, liver, yeast, almonds and mature soybeans are good sources of vitamin B₂, but exposure to light will destroy the riboflavin in these natural sources. Any excess is excreted in the urine, frequently imparting a bright yellow color. As the human body does not store riboflavin it is thought deficiency is common.

In processed foods it is very likely to have been produced synthetically using genetically modified Bacillus subtilis, altered to both increase the bacteria's production of riboflavin and to introduce an antibiotic (ampicillin) resistance marker.

Riboflavin is yellow or orange-yellow in colour and in addition to being used as a food colouring it is also used to fortify some foods. It can be found in baby foods, breakfast cereals, sauces, processed cheese, fruit drinks and vitamin-enriched milk products as well as being widely used in vitamin supplements. Riboflavin is responsible for the harmless side effect of coloring a vitamin taker's urine bright yellow.

It is difficult to incorporate riboflavin into many liquid products because it has poor solubility in water. Hence the requirement for E101a riboflavin-5'-phosphate, a more expensive but more soluble form of riboflavin.

Nutrition

Riboflavin Deficiency

A deficiency of riboflavin can be primary - due to not getting enough of the vitamin from the diet - or secondary, which may be a result of conditions that affect absorption in the intestine, the body not being able to use the vitamin, or an increase in the excretion of the vitamin from the body..

In humans, signs and symptoms of riboflavin deficiency (ariboflavinosis) include cracked and red lips, inflammation of the lining of mouth and tongue, mouth ulcers, cracks at the corners of the mouth (angular cheilitis), and a sore throat. A deficiency may also cause dry and scaling skin, fluid in the mucous membranes, and iron-deficiency anemia. The eyes may also become bloodshot, itchy, watery and sensitive to bright light.

In animals, riboflavin deficiency results in lack of growth, failure to thrive, and eventual death. Experimental riboflavin deficiency in dogs results in growth failure, weakness, ataxia, and inability to stand. The animals collapse, become comatose, and die. During the deficiency state, dermatitis develops together with hair-loss. Other signs include corneal opacity, lenticular cataracts, hemorrhagic adrenals, fatty degeneration of the kidney and liver, and inflammation of the mucus membrane of the gastrointestinal tract. Post-mortem studies in rhesus monkeys fed a riboflavin-deficient diet revealed that about one-third the normal amount of riboflavin was present in the liver, which is the main storage organ for riboflavin in mammals. These overt clinical signs of riboflavin deficiency are rarely seen among inhabitants of the developed countries. However, about 28 million Americans exhibit a common ‘sub-clinical’ stage, characterized by a change in biochemical indices (e.g. reduced plasma erythrocyte glutathione reductase levels). Although the effects of long-term sub-clinical riboflavin deficiency are unknown, in children this deficiency results in reduced growth. Subclinical riboflavin deficiency has also been observed in women taking oral contraceptives, in the elderly, in people with eating disorders, and in disease states such as HIV, inflammatory bowel disease, diabetes and chronic heart disease. The fact that riboflavin deficiency does not immediately lead to gross clinical manifestations indicates that the systemic levels of this essential vitamin are tightly regulated.

Diagnostic Testing of B2 Deficiency

A positive diagnostic test for measuring levels of riboflavin in serum is assertained by measuring erythrocyte levels of glutathione reductase.

Clinical Uses

Riboflavin has been used in several clinical and therapeutic situations. For over 30 years, riboflavin supplements have been used as part of the phototherapy treatment of neonatal jaundice. The light used to irradiate the infants breaks down not only the toxin causing the jaundice, but the naturally occurring riboflavin within the infant's blood as well.

More recently there has been growing evidence that supplemental riboflavin may be a useful additive along with beta-blockers in the treatment of migraine headaches.

Development is underway to use riboflavin to improve the safety of transfused blood by reducing pathogens found in collected blood. Riboflavin attaches itself to the nucleic acids (DNA and RNA) in cells, and when light is applied, the nucleic acids are broken, effectively killing those cells. The technology has been shown to be effective for inactivating pathogens in all three major blood components: (platelets, red blood cells, and plasma). It has been shown to inactivate a broad spectrum of pathogens, including known and emerging viruses, bacteria, and parasites.

Good sources

Riboflavin is found naturally in asparagus, okra, chard, cottage cheese, milk, yogurt, meat, eggs, and fish, each of which contain at least 0.1 mg of the vitamin per 3-10.5 oz (85-300 g) serving.

References

Jane Higdon, "Riboflavin", Micronutrient Information Center, Linus Pauling Institute, Oregon State University

Template:ChemicalSources

Mirasol PRT includes a brief description of riboflavin as an agent to inactivate pathogens.