VITAMINB2[RIBOFLAVIN] MEDICINAL CHEMISTRY,BY P.RAVISANKAR [SOURCES OF VITAMIN B2,CHEMISTRY OF VITAMIN B2,PHYSIOLOGICAL IMPORTANCE,SYNTHESIS OF RIBOFLAVIN,REACTIONS, VITAMIN B2 DEFICIENCY SYMPTOMS,FUNCTIONS,USES OF RIBOFLAVIN. BY P.RAVISANKAR,VIGNAN PHARMACY COLLEGE, VADLAMUDI, GUNTUR, ANDHRA PRADESH, INDIA.

1. (Riboflavin) (lactoflavin)Vitamin B2 (lactoflavin)
N
N
NH
N
Me
Me
O
O
CH2OH
(HO-C-H)3
CH2
Ribose moiety
Vit B2 = Riboflavin
Isoalloxazine moiety
3
Prof. Ravisankar
Vignan Pharmacy college
Valdlamudi
Guntur Dist.
Andhra Pradesh
India.
banuman35@gmail.com
00919059994000

2. VITAMIN B2 (Riboflavin)
Vitamin B2, also known as riboflavin, is an organic compound you can find in
many plant and animal products.
It is water soluble vitamin. It aids in the metabolism of your fats, carbohydrates,
protein and ketone bodies.It is also important for your energy metabolism
The vitamin is water-soluble--your body can't store it--so you should be eating
foods rich in vitamin B2 every day to maintain your body's energy supply.
VitaminB2 is destroyed by exposure to light, therefore foods with riboflavin should
be keep in dark or opaque containers.
Vitamin B2 is closely related to the yellow water-soluble pigments known as
flavines(isoalloxazines), and since it was first isolated from milk, vitamin B2 is also
known as lactoflavin.
Riboflavin is a bright yellow powder,slight odour,bitter taste,slightly soluble in
water and alcohol but insoluble in acetone . It is heat stable with decomposition
occuring at 2800
C.
Riboflavin has a fluorescent property in aqueous solution which is yellow and
shows and shows yellowish-green fluorescence has a λ-max 565nm.This
property has been used as a means of determining riboflavin quantitatively.

3. sources of vitamin B2
Good sources of Riboflavin
include:
dietary sources:
Milk, cheese,
oily fish,
liver,kedney,
heart,
meat, fish, eggs,
cereal products,
green leafy vegetables,
whole grains, brewer's
yeast, wheat germ,
almonds,
sunflower seeds.
dairy products,
Red meats,
bread,cashews,
soybeans.millet,peppers,
Sources of vitamin B2 (riboflavin)
Sources of riboflavin include organ meats (liver, kidney, and heart)
certain plants such as almonds, mushrooms, whole grain, soybeans.
Flour and cereals are enriched with riboflavin.
Riboflavin is stable when heated but will leach into cooking water.

4. • avocado
• -banana
• -dates
• -grapes
• -pomegranate
• -artichoke
• -asparagus
• -broccoli
• -peas
• -sweet potatoes
almonds
milk
pomegranate
vegetables

5. chemistry:
The structure of Riboflavin consists of
6,7-dimethyl-isoalloxazine (heterocyclic three
ring system) to which a sugar alcohol group called
ribitoyl group is attached at 9th
position.
Urea
β-ketocarboxylic acid

6. • Stable to heat, oxidation, and acid,
riboflavin is somewhat soluble in water.
• Light and alkali destroy it.
• It should be noted that bottled milk
(which has a relatively large amount of
vitamin B2), loses a significant amount of
vitamin B2 if it is left in the sunlight.

7. • Physiological importance:
• Riboflavin is the component of two flavin enzymes the flavin
mononucleotide(FMN)
and the flavin adenine dinucleotide.
Both these flavin enzymes take part in various oxidation-reduction reactions.
The oxidized flavines are yellow in colour while upon reduction (one hydrogen
atom at 1 and other at 10 positions acquisition occurs) and they become
colourless.
N
N
N
N O
H
O
H3C
H3C
N
N
N
N O
H
O
H3C
H3C
H
H
FAD (oxidized form) FADH2 (reduced form)
hydrogen addition
occurs in 2 steps
(FMN or FAD) (FMNH2 or FADH2)
2H+
-2H+
This reaction can also proceed in the reverse direction.
1
10

9. • Both the coenzymes function with a group of proteins known as the
flavoproteins.
• These flavoproteins due to their diverse nature can act as
oxidases,dehydrogenases,hydroxylases,oxidative decorboxylases.
-Riboflavin and its coenzymes are also involved in
- Growth and tissue respiration
- Light adaptation.
-Conversion of pyridoxine to pyridoxal phosphate.
-cellular metabolism.
-Enzymatic oxidation of glucose,amino acids,fatty acids,purines etc.
Riboflavin or vitamin B2 is an essential nutrient in human nutrition and plays a
key role in the production of energy.
• Vitamin B2 is needed to process amino acids and fats, activate vitamin B6 and
folic acid, and help convert carbohydrates into the fuel the body runs on.
Under some conditions, vitamin B2 can act as an antioxidant.
• Vitamin B2 is an intermediary the transfer of electrons in the cellular
oxidation-reduction reactions which generate energy from protein,
carbohydrate and fat.

10. • 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.
• The riboflavin coenzymes are also important for the transformation of
vitamin B6 and folic acid into their respective active forms, and for the
conversion of tryptophan into niacin.
• Riboflavin is involved in energy production as part of the electron transport
chain that produces cellular energy.
• Adverse effects:
Riboflavin does not cause any adverse effects.
Infact excess of riboflavin therapy increases the urine colour to bright yellow
(flavinuria)which is harmless.

11. SYNTHESIS OF RIBOFLAVIN
Kuhn synthesis:

12. In alkaline solution of riboflavin,when irradiated yields
lumiflavin(6,7,9-trimethyl flavin).
Reactions:
when exposed
to light.
in NaOH solution
forms...
Exposure of neutral solution
of lactoflavin to light to produce
lumichrome.
The lumichrome is lumilactoflavin with a
hydrogen atom imstead of a methyl group at position9.

13. Lumichrome(6,7- dimethyl alloxazine)
isoalloxazine
The isoalloxazine is a tautomer of the alloxazine does not exist as such
but this structure is fixed when there is a substitution at position 9.
Alloxazine.

14. • VITAMIN B2 DEFICIENCY SYMPTOMS
• Symptoms can include:
• Cheilosis(fissues at the corners of the mouth and lips), swollen tongue
or gums.
Seborrhoeic dermatitis (secretion of sebum),glossitis(inflammation of
tongue)
lacrimation, patients suffering from pellagra and beriberi also suffring
from ariboflavinosis.(it is a vitamin B2 deficiency characterized by a
group of symptoms and almost symptoms of other vitamin B-complex
vitamins.
Inflammationmouth,pharynx,throat,keratitis,anaemia,neuropathy,photo
phobia,general weakness and growth reduction.
Cracked skin especially around the mouth, Scaly red skin on the sides
of the nose, Sensitivity to bright lights, Insomnia, Conjunctivitis,
Bloodshot/sore eyes (itchy eyes)Chronic fatigue.

15. • .
• In animals riboflavin deficiencies cause alopecia, anemia, neuropathy, corneal
vascularization (precataracts) and congenital malformations.
Some of the symptoms of deficiency of riboflavin are, cracked lips,
cracked corners of mouth, sores in the mouth, general debility, fatigue,
sore tongue and sore throat, eye fatigue, light sensitivity, inflamed
mucous membrane, dry and scaly skin and iron-deficiency anaemia.
.
Cracked corners of the mouth.
(Cheilosis)

16. • function:
• Riboflavin is involved with production of FMN and FAD, both of which are involved
in redox reactions.
• Riboflavin causes the activation of vitamin B6.
• Riboflavin is involved in the conversion of tryptophan to niacin.
• Riboflavin is involved in the conversion of folate to its coenzymes.
• Riboflavin aids in Beta oxidation in fat metabolism.
• Riboflavin is involved as a coenzyme component of the dehydrogenases in the first
step in glucose metabolism.
• Riboflavin is needed for the production of corticosteroids; erythropoiesis;
gluconeogenesis; and thyroid enzyme regulation.
• The functions of the B2 Vitamin are to aid in the metabolism of fats, proteins and
carbs, healthy skin, nails, and hair growth, convert your carbs into energy and tissue
respiration. These are all essential for a healthy body.
• There are also many benefits of this vitamin as well. It actually neutralizes the free
radicals in your body and can help prevent heart disease and cancer. It also helps to
keep the mucous membranes in your body healthy including those in your mouth.
And, believe it or not, it also aids in the prevention of headaches, vision problems
and even cataracts
• In the prevention and treatment of ariboflavinosis.(this deficiency can be treated with
an oral daily dose of 3-10mg.
A recent investigation has found that it is effective in treating migraine.
.

17. • Riboflavin is an integral component of the coenzymes that participate in many
energy-yielding metabolic pathways.
• riboflavin plays a crucial role in certain metabolic reactions, particularly the
conversion of carbohydrates into sugar, which is "burned" to produce energy.
They promote the first steps in the metabolism (breakdown and production) of
glucose and of fatty acids.
• The metabolism of some vitamins and minerals also require riboflavin.
• Riboflavin is essential for tissue respiration and the generation of energy from
the carbohydrates, acids and fats.
• It is important for body growth and red blood cell production and helps in
releasing energy from carbohydrates.
• Vitamin B2 helps prevent and is used to treat migraine headaches, cataracts,
rheumatoid arthritis, and a number of skin disorders such as acne (acne
rosacea), dermatitis, and eczema.
• In the treatment of anemia, adding Vitamin B2 to iron supplements has shown
to increase its effectiveness.
• Vital to maintaining a proper metabolism, riboflavin also helps to shore up the
immune system by reinforcing antibody reserves, the body's first line of
defense against infection.
•

18. • Along with iron, riboflavin is essential for producing the red blood cells that carry
oxygen throughout the body.
• In addition, the body uses extra riboflavin to keep tissue in good repair and speed
healing of wounds, burns and other injuries.
• Along with such B vitamins as vitamin B6 and niacin (which it helps the body convert
into active forms), riboflavin protects the nervous system.
• It may therefore have a role to play in treating nervous system conditions such
as numbness and tingling, Alzheimer's disease, epilepsy, multiple sclerosis,
and even anxiety, stress, and fatigue. Carpal tunnel syndrome may benefit from a
treatment program including this vitamin when combined with vitamin B6.
• The body needs vitamin B2 for reproduction and it also enhances the immune
system's ability to fight disease.
• .Riboflavin is vital for normal reproduction, growth, repair and development of
body tissues including the skin, hair, nails, connective tissue and immune
system.
• Riboflavin (vitamin B2) works with the other B vitamins. Dietary and supplemental
vitamin B2, along with other nutrients is important for normal vision and prevention
of cataracts.
• Riboflavin's ability to improve the skin's secretion of mucus may aid in clearing up
skin pustules associated with rosacea.
riboflavin facilitates absorption of iron from foods, mobilization of iron throughout the
body, and retention and utilization of iron within the body.

19. • RDA recommends 1.7 mg for males and 1.3 mg for females
• Vitamin B2 or riboflavin is important for body growth, reproduction and red
cell production.
It also helps in releasing energy from carbohydrates. Vitamin B2 (Riboflavin)
Vitamin B2 helps turn fats, sugars and protein into energy.
• Vitamin B2 is needed to repair and maintain healthy skin, inside and out, it
helps to regulate body acidity and is important for optimun health of hair nails
and eyes.
• Vitamin B2 is a water-soluble Vitamin needed to process amino acids and fats,
activate Vitamin B6 and folic acid, and help convert carbohydrates into the fuel
that the body runs on—adenosine triphosphate (ATP).
USES
OF RIBOFLAVIN

20. Uses:
It helps to convert food into energy.
It is also needed to convert an amino acid called tryptophan into niacin.
It works closely with other B vitamins.
It helps make red blood cells and it keeps body tissues healthy, especially the skin
and eyes.
It is key to healthy growth and development.
It helps the body make and control certain hormones.
Acne rosacea, anemia (rare), athletic performance, cataracts, depression, migraine
headaches.
Acts as a coenzyme in converting, proteins, fats and carbohydrates into energy,
Helps to counteract free radical damage, Aids vision and prevents cataract
formation, Maintains the integrity of mucous membrane, Promotes skin, hair and
nail health, Activates vitamin B6, protects against anaemia, Helps in the
prevention of migraine headaches.
It helps the normal functioning of the digestive system

21. • .
Riboflavin is believed to have an important function in the synthesis and transcription of DNA.
Riboflavin participates in redox (oxidation-reduction) reactions to metabolise fats, proteins and
carbohydrates to produce energy.
Riboflavin is one of the coenzymes responsible for the energy release in mitochondria from
the fatty acids and glucose.
Riboflavin also helps in the metabolism of toxins and drugs and protects the body from their
harmful effects.
In various ways vitamin B2 functions as an antioxidant neutralising the free radicals and
protects the body from their ill-effects.
Riboflavin helps in the growth and maintenance of red blood cells. It also supports the health
of white blood cells, which are responsible for immunity and protection from antigens.
Many biochemical processes are brought about by the vitamin B2.
Pantothenic acid and folate are converted into neurotransmitters by riboflavin for cognizance
and memory.
High serum levels of riboflavin are found to connect to excellent performances in memory tests.
Riboflavin is found to alleviate the conditions responsible for migraine.
Vitamin B2 is found to be important for the healthy eyes and also may help in prevention of
cataracts.
Riboflavin keeps the mucous membrane healthy and its role in the health of hair, nails and
skin is well-known.