Docsity
Log inSign up
Docsity
Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity

Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan

Guidelines and tips
Guidelines and tips
Sell on Docsity
Sell on Docsity
Log inSign up

Prepare for your exams

Study with the several resources on Docsity

Find documents

Prepare for your exams with the study notes shared by other students like you on Docsity

Search Store documents

The best documents sold by students who completed their studies

Search through all study resources
Docsity AINEW

Summarize your documents, ask them questions, convert them into quizzes and concept maps

Explore questions

Clear up your doubts by reading the answers to questions asked by your fellow students

Earn points to download

Earn points by helping other students or get them with a premium plan

Share documents
download point icon20 Points

For each uploaded document

Answer questions
download point icon5 Points

For each given answer (max 1 per day)

All the ways to get free points
Get points immediately

Choose a premium plan with all the points you need

Study Opportunities

Choose your next study program

Get in touch with the best universities in the world. Search through thousands of universities and official partners

Community

Ask the community

Ask the community for help and clear up your study doubts

University Rankings

Discover the best universities in your country according to Docsity users

Free resources

Our save-the-student-ebooks!

Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors

From our blog

Exams and Study
Go to the blog

Chemistry, Sources, RDA, Functions, and Deficiency Manifestations of Vitamins A, D, and C, Summaries of Bioorganic Chemistry

Rajiv Gandhi UniversityBioorganic Chemistry

Detailed information about the chemistry, sources, recommended dietary allowance (rda), functions, and deficiency manifestations of three essential vitamins: vitamin a, vitamin d, and vitamin c. It explains the different compounds that make up each vitamin, their dietary sources, the roles they play in the body, and the symptoms of deficiency. It also discusses the absorption, storage, and metabolism of each vitamin.

Typology: Summaries

2021/2022

Uploaded on 03/08/2024

jaya-vel
jaya-vel 🇮🇳

2 documents

1 / 13

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
BIOCHEMISTRY PROJECT - VITAMINS
Q1) Describe the Chemistry , Sources , RDA , Functions and Deficiency Manifestations of
Vitamin - A
Ans1) VITAMIN-A
CHEMISTRY
• Two groups of compounds have Vitamin A activity :- 1) Retinoids comprising of Retinal,
Retinol and Retinoic acid
2) Carotenoids comprising of Carotenes & related compounds.
• Beta carotene has two beta ionone rings connected to a Polyprenoid chain.
• One molecule of beta Carotene can theoretically give rise to two molecules of Vitamin A, But
may produce only one in Biological System.
• All compounds with Vitamin A activity are reffered to as Retinoids.
• Three different compounds with Vitamin A activity are :-
1) Retinal (Vit. A Aldehyde)
2) Retinol (Vit. A Alcohol)
3) Retinoic Acid(Vit. A Acid)
• The Retinal may be reduced to Retinol by Retinal Reductase, It is Reversible.
• Retinoic acid is formed on oxidation of Retinal, Irreversible reaction.
• Retinoic acid cannot give rise to the formation of Retinal or Retinol.
•Most Common -> Vitamin A1 (All-trans variety of Retinal)
•Biologically Most Important -> 11-Cis-Retinal
DIETARY SOURCE
•Animal sources - Milk , Butter , Cream , Egg Yolk.
pf3
pf4
pf5
pf8
pf9
pfa
pfd

Partial preview of the text

Download Chemistry, Sources, RDA, Functions, and Deficiency Manifestations of Vitamins A, D, and C and more Summaries Bioorganic Chemistry in PDF only on Docsity!

BIOCHEMISTRY PROJECT - VITAMINS

Q1) Describe the Chemistry , Sources , RDA , Functions and Deficiency Manifestations of Vitamin - A

Ans1) VITAMIN-A

CHEMISTRY

  • Two groups of compounds have Vitamin A activity :- 1) Retinoids comprising of Retinal, Retinol and Retinoic acid
  1. Carotenoids comprising of Carotenes & related compounds.
  • Beta carotene has two beta ionone rings connected to a Polyprenoid chain.
  • One molecule of beta Carotene can theoretically give rise to two molecules of Vitamin A, But may produce only one in Biological System.
  • All compounds with Vitamin A activity are reffered to as Retinoids.
  • Three different compounds with Vitamin A activity are :-
    1. Retinal (Vit. A Aldehyde)
    2. Retinol (Vit. A Alcohol)
    3. Retinoic Acid (Vit. A Acid)
  • The Retinal may be reduced to Retinol by Retinal Reductase, It is Reversible.
  • Retinoic acid is formed on oxidation of Retinal, Irreversible reaction.
  • Retinoic acid cannot give rise to the formation of Retinal or Retinol.
  • Most Common -> Vitamin A1 (All-trans variety of Retinal)
  • Biologically Most Important -> 11-Cis-Retinal DIETARY SOURCE
  • Animal sources - Milk , Butter , Cream , Egg Yolk.
  • Vegetable sources - Contain Yellow pigment beta Carotene , Pumpkins, Carrot, Green leafy vegetables, Papaya, Mango etc
  • Fish Liver oils are very rich sources of Vitamin A. RECOMMENDED DIETARY ALLOWANCE (RDA)
  1. Children -> 400-600 μg/day
  2. Men -> 750-1000 μg/day
  3. Women -> 750 μg/day
  4. Pregnancy -> 1000 μg/day. ABSORPTION
    • Vitamin A is absorbed in the small intestine.
  • Vitamin E [Tocopherols] & other antioxidants protect them against oxidation and destruction in Intestinal Lumen.
  • Beta carotene is cleaved by a di-oxygenase, to form Retinal.
  • The Retinol is reduced to retinal by an NADH dependent retinal reductase present in the Intestinal Lumen.
  • Absorption is along with other fats & requires Bile salts.
  • Within Mucosal cell, the retinol is re-esterefied with fatty acids, incorporated into Chylomicrons and transported to Liver. STORAGE
  • In Liver Stellate cells, Vitamin is stored as Retinol Palmitate. TRANSPORT
  • Vitamin A from liver is transported to Peripheral tissues as Trans-Retinal by the Retinal Binding Protein (RBP). BIOCHEMICAL FUNCTIONS
  1. Vitamin A is necessary for a variety of functions such as :- a) Vision
  • This leads to a conformational change in Opsin which is responsible for the generation of Nerve impulse
  • The All-trans-retinal is immediately isomerized by retinal isomerase (of retinal epithelium) to 11- cis-retinal.
  • This combines with opsin to regenerate rhodopsin and complete the visual cycle.
  • However, the conversion of all-trans-retinal to 11-cis-retinal is incomplete.
  • Therefore, most of the all-trans-retinal is transported to the Liver and converted to all-trans-retino l by Alcohol dehydrogenase.
  • The All-trans-retinol undergoes isomerization to 11- cis retinol which is then oxidised to 11-cis-retinal to participate in the Visual Cycle. DEFICIENCY MANIFESTATIONS OF VITAMIN A
  1. Nyctalopia/Night Blindness
  • Visual activity is diminished in dim light.
  • The patient cannot read or drive a car in poor light. •The dark adaptation time is increased.
  1. Xerophthalmia
  • The conjunctiva becomes dry, thick & wrinkled . • The conjonctiva gets Keratinized & loses its normal transparency. Dryness spreads to cornea.
  1. Bitet's Spots
    • Seen as grayish-white Triangular plaques firmly adherent to the conjunctiva, due to increased thickness of conjunctiva
  2. Keratomalacia When the Xerophthalmia persists for a long time, it progresses to Keratomalacia (softening of the Cornea). Degeneration of Corneal epithelium may lead to total blindness. VITAMIN A TOXICITY / HYPERVITAMINOSIS A
  • Excessive consumption of Vitamin A leads to Toxicity.
  • Symptoms include :-
  1. Loss of Weight
  2. Irritability
  3. Loss hair
  4. Joint pain s) Dermatitis
  5. Enlargement of Liver.
  6. Skeletal Decalcification. Q2) Describe the Chemistry , Sources , RDA , Functions and Deficiency Manifestations of Vitamin - D

Ans2) VITAMIN-D

CHEMISTRY

  • Vitamin D is a fat soluble Vitamin.
  • Resembles steroids in structure & functions like a Hormone.
  • Vitamin D is derived either from 7- Dehydrocholestrol or Ergosterol by the action of UV radiations.
  • In the skin, UV light breaks the bond b/w position 9 & 10 of the steroid ring.
  • So, the ring B is opened, to form the provitamin, Secosterol.
  • The cis double bond b/w 5th & 6th Carbon atoms, is then Isomerized to trans double bond to give rise to Vitamin D3 or Cholecalciferol
  • So, Vitamin D is called the " Sun- Shine Vitamin ".
  1. Ergocalciferol [Vit D2] -> formed from ergosterol, present in plants.
  2. Cholecalciferol [Vit D3] -> found in Animals.
  • They are metabolized identically in the body and converted to Active forms.
  • Cholecalciferol is first hydroxylated at 25th position to 25- Hydroxy cholecalciferal (25-OH D3) by a specific hydroxylase present in Liver
  • 25-OH D3 is the major storage & circulatory form of Vit·D.
  • 25-Hydroxy cholecalciferal is hydroxylated at 1st position to produce 1,25-Dihydroxycholecalciferal (1,25-DHCC) by a specific enzyme present in the kidney called 25-Hydroxycholecalciferal (calcidiol) 1- Hydroxylase.
  • 1,25-DHCC contains 3 Hydroxyl groups (1,3 & 25) Hence referred to as Calcitriol. BIOCHEMICAL FUNCTIONS
  1. Calcitriol [1,25-DHCC) is the biologically active form of Vitamin D
  2. It regulates the plasma levels of Calcium & Phosphate.
  3. Calcitriol acts at 3 different levels [Intestine, Kidney & Bone] to Maintain plasma calcium [Normal range -> 9-11 mg/dl].
  4. Action of Calcitriol the Intestine :-
  • Calcitriol increases the Intestinal absorption of Calcium & Phosphate
  • In the intestinal cells, Calcitriol binds with a cytosolic receptor to form a Calcitriol-receptor complex.
  • This complex approaches the Nucleus & interacts with a specific DNA leading to the synthesis of a specific Calcium Binding protein.
  • This protein increases the Calcium uptake by the Intestine.
  1. Action of Calcitriol on the Bones :-
  • In Osteoblasts of Bone, Calcitriol stimulates calcium uptake for deposition as calcium phosphate. Thus Calcitriol is essential for Bone Formation.
  • Bone is important reservoir of Calcium & Phosphate.
  1. Action of Calcitriol on the Kidney :-
  • Calcitriol conserves Calcium & Phosphorous by minimizing their excretion through Kidneys & stimulating their reabsorption.
    • Acts in co-operatiion with PTH. DEFICIENCY MANIFESTATIONS
  1. Rickets
  • Rickets in Children is characterized by Bone deformities due to incomplete mineralization, resulting in soft & pliable bones & delay in teeth formation.
  • In rickets, the plasma level of Calcitriol is decreased & Alkaline Phosphatale activity is elevated.
  • The weight-bearing bones are bent to form:-
  1. Bow-legs
  2. Knock knees,
  3. Pigeon Chest
  4. Osteomalacia
  • The bones are softened due to insufficient mineralization & increased Osteoporosis.
  • Patients are more prone to get fractures.
    1. Renal Rickets [Renal Osteodystrophy].
  • Seen in patients with Chronic renal failure.
  • Mainly due to decreased synthesis cef Calcitriol in Kidney,
  • Can be treated by administration of Calcitriol.
  • The acidic property of Vit. C is due to the enolic hydroxyl groups.
  • It is a Strong Reducing agent.
  • L-ascorbic acid undergoes oxidation to form dehydroascorbic acid, Reversible reaction.
  • Biologically active -> Ascorbic acid & Dehydroalcorbic acid.
    • Biologically inactive -> D-ascorbic acid. DIETARY SOURCES
  • Good sources -> Citrous fruits - Orange / Lemon, other fruits -> Banana, Strawberry, Papaya, Pineapple. •Vegetables -> Green leafy vegetables -> Cabbage, Cauliflower, Green peas, Potatoes, Tomatoes. RECOMMENDED DIETARY ALLOWANCE
  • RDA is -> 75mg/day
  • During Pregnancy , Lactation and Aged People -> 100mg/day METABOLISM OF ASCORBIC ACID
  • Ascorbic acid is readily absorbed from gastrointestinal tract. The Vitamin is excreted in urine.
  • Since Vitamin C is a strong reducing agent, the Benedict's test will be positive in urine sample after the Vitamin administration.
  • Oxidation of ascorbic acid yields dehydro ascorbic acid, which is oxidized further to oxalic acid through diketo-L-gulonic acid.
  • Ascorbic acid is partly excreted unchanged and partly as oxalic acid. Most of the oxalates in urine are derived from ascorbic acid, and the rest from glycine metabolism. BIOCHEMICAL FUNCTIONS
  1. Ascorbic acid is Water soluble antioxidant. [Ascorbic acid is a strong reducing agent & acts as an antioxidant]
  1. It reduces oxidized Vitamin E & [ Tocopherol] to regenerate functional Vit·E.
  2. Prevents Atherosclerosis & coronary heart disease by preventing oxidation of LDL.
  3. Antioxditant Property of Vit C is also associated with prevention of cancer by inhibiting Nitrosamine formation from naturally occurring Nitrates during digestion.
  4. Vitamin C concentrated in the lens of eye. Regular intake of Vitamin C reduces risks of Cataract.
  5. Action on certain Enzymes - Activation/ Inhibition.
  • Vit.C is capable of both activating & inhibiting different groups of enzymes.
  • Arginase & papain are activated.
  • Urease & Beta-Amylase are inhibited.
  1. Collagen Synthesis
  • Vitamin C is required for formation of Collagen , where it is needed for the Hydroxylation of Proline & Lysine residues of Protocol lagen.
  • Hydroxyproline & Hydroxylysine are essential for the collagen cross-linking & Stability.
  • Vitamin C is also involved in Bone & Dentin formation as well as Wound Healing Process.
  1. Steroid Synthesis
    • In Adrenal cortex, Vit C is involved in the Hydroxylation reactions of Steroids.
    1. Adrenaline Synthesis
    • In Adrenal medulla it serves as a reducing agent in Hydroxylation reactions in the synthesis of Adrenaline & Noradrenaline from Tyrosine.
  2. Immunological function
    • Vit C enhances the synthesis of Immunoglobulins [Antibodies] & Increases the Phagocytic action of Leucocytes
  3. Carnitine Synthesis
  1. Easy bruising & bleeding due to fragile capillaries.
  2. Wound Healing is delayed due to deficient collagen formation.
  3. Capillaries are fragile & there is tendency to Hemorrhage Petechial, subcutaneous, subperiosteal & even internal Haemorrhage can Occur.