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Drug Action II > Block 2: Vitamin Intro + Vitamin C > Flashcards

Block 2: Vitamin Intro + Vitamin C Flashcards

1
Q

Night blindness is caused by a deficiency in what vitamin?

A

A

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2
Q

What is a vitamin?

A

An essential organic compound required in small amounts important for the functions of the body

Not metabolic fuels or structural nutrients but rather regulators for energy metabolism

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3
Q

What vitamin is synthesized by most mammals except for humans?

A

C

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4
Q

What vitamin is synthesized by rumen bacteria?

A

B

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5
Q

Vitamins undergo a chemical change from ____?

A

Provitamins

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6
Q

What are some of the functions of vitamins?

A
  1. Hormones
  2. Antioxidants
  3. Mediators of cell signalling and regulators of cell and tissue growth and differentiation
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7
Q

Chemical name: Vitamin A

Deficiency?

A

Retinoid (retinol, retinoids, carotenoids)

Night blindness and keratomalacia

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8
Q

Chemical name: Vitamin B1

A

Thiamine

Beriberi

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9
Q

Chemical name: Vitamin B2

A

Riboflavin

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10
Q

Chemical name: Vitamin B3

Deficiency

A

Niacin

Pellagra

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11
Q

Chemical name: Vitamin B5

Deficiency?

A

Pantothenic acid

Paresthesia

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12
Q

Chemical name: Vitamin B6

Deficiency?

A

Pyridoxine, pyridoxamine, pyridoxal

Anemia

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13
Q

Chemical name: Vitamin B7

Deficiency?

A

Biotin

Dermatitis

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14
Q

Chemical name: Vitamin B9

Deficiency

A

Folic acid

Neural tube defect

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15
Q

Chemical name: Vitamin B12

Deficiency

A

Cyanocobalamin, Hydroxycobalamin, methylcobalamin

Megaloblastic anemia

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16
Q

Chemical name: Vitamin C

Deficiency?

A

Ascorbic acid

Scurvy

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17
Q

Chemical name: Vitamin D

Deficiency

A

Ergocalciferol, cholecalciferol

Rickets and osteomalacia

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18
Q

Chemical name: Vitamin E

A

Tocopherols, tocotrienols

19
Q

Chemical name: Vitamin K

Deficiency?

A

Phylloquinone, menaquinones

Bleeding diathesis

20
Q

What is the differnce between a primary and secondary vit def?

A

Primary: Occurs when an organism doesn’t get enough vitamins from food
Secondary: Due to an underlying disorder that prevents or limits absorption and use of vitamins

21
Q

What are the general ADRs of vitamin OD?

A

N/D/V

22
Q

How is vitamin manufacturing regulated?

A

FDA label them as Dietary Supplements not intended to treat only to supplement diet

23
Q

Why are mammals more susceptible to scurvy?

A

The liver’s inability to produce the active enzyme L-gulonolactone oxidase an enzyme required for Vit C synthesis

24
Q

What are the sx of scurvy?

A
  1. Liver spots on skin
  2. Spongy gums
  3. Bleeding
  4. Suppurating wounds
  5. Loss of teeth
  6. Death

Body soon depletes itself (20-40 days)

25
Q

How is vitmain C mass synthesized?

A

Redoxon: D-sorbitol undergoes several redox reactions (reichstein process) to become ascorbic acid

26
Q

What is the MOA of scurvey?

A

The liver’s inability to produce the active enzyme L-gulonolactone oxidase inhibiting the progresion of Vitamin C biosynthesis

27
Q

What is the active form of Vitamin C? How does this affect metals?

A

L-ascorbic acid is a stron reducing agent that reverses oxidation (anti-oxidant)

L-ascorbic can reduce metals to their pro-oxidant form for coenzymatic activity

28
Q

Why are free radicals and ROS bad? How are they resolved?

A

Attack phospholipids and proteins in the cell membrane via lipid peroxidation

Ascorbic acid reduces and deactivated ROS

29
Q

How can Vitamin C cause kidney stones?

A

Exccesive Vitamin C produces the metabolite Oxalic acid that promotes the formation of kidney stones

30
Q

Describe how the vitamin C contributes to collagen formation?

A
  1. Vit C requires to 2 hydroxylation reactions of proline or lysine (amino acids important for scurvy protection)
  2. Proline residue on collagen a-chains is hydrolyzed to aggregate into triple helix
  3. Fe3+ reduces to Fe2+ when converting ascorbate to dehydroascobate
31
Q

Why is hydroxylation reactions of proline and lysine important?

A

Hydroxylation stabilizes the exo-conformation for collagen structure enhancing H-bond stabilizing the triple helix

32
Q

What is carnitine synthesis?

A

Significant in fat metabolism where vitamin C undergoes 2 hydrolysis reactions:
1. tri-methyl lysine is catalyzed by iron containing TML dioxygenase to 3-hydroxyl TML
2. 4-butyrobetaine catalyzed by iron-containing 4BB hydroxylase to carnitine

Vitamin C maintains the enzymes iron reduced, active form

33
Q

Describe the mechanism of tyrosine biosynthesis and metabolism?

A

Vitamin C catalyzes the following reactions:
1. Tyrosine is formed from phenylalanine hydroxylation by phenylalanine monooxygenase
2. Used for Cu++ dependent p-hydroxyphenyl pyruvate hydroxylase metabolizing tyrosine

34
Q

What neurotransmitter and hormon is catalyzed by Vit C?

A

Vitamin C enhances the activity of 2 Cu2+ requiring enzymes for the biosynthesis of NE and adrenal hormone

1Tyrosine -> Dopamine -> NE

35
Q

How does vitamin C assist with serotonin synthesis?

A

Vit C, folic acid, and O2 assist with the hydroxylation of tryptophan for synthesizing serotonin in the brain

36
Q

Vitmain C enhances the absorption of what elements?

A
  1. Iron
  2. Copper
  3. Chromium
37
Q

How does vitamin C assist bile synthesis?

A

Hydroxylation/degradation of cholesterol steroid nucleus by cholesterol 7a hydroxylase (diminished action with vit C def)

38
Q

How is Vit C absorbed into the body?

A

Absorbed in the distal small intestine via active transport by a glucose transport protein

39
Q

Where is the highest concentration of vitamin C found?

A

Adrenal gland (30-40 mg/100g wet tissue)

40
Q

How can Vit C prevent cancer?

A

Vit C has antineoplastic properties against stomach and esophagus cancers when ingested with nitrates and nitrites preventing the formation of carcinogenic nitrosamines

41
Q

What are the sx of vitamin C toxicity?

A
  1. Kidney stones and gout due to increased uric acid
  2. Osmotic diarrhea
  3. Iron poisoning due to increased absoprtion
42
Q
A
43
Q

What are the important functions of vitamin C?

A
  1. Antioxidant
  2. Amino acid hydroxylation
  3. Tyrosine biosynthesis
  4. Biosynthesis of NE, adrenal hormone, serotonin

Drug Action II (28 decks)

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