28. Lipotropic factors (choline, inositol).

Question 1

Choline structure:

Answer 1

-

Question 2

Choline dietary form:

Answer 2

Lecithin mainly, free base or sphingomyelin

Question 3

Where do you find choline:

Answer 3

Feeds with vitamin B family, egg yolk, liver, soybean, wheat germ.

Question 4

Where is choline stored?

Answer 4

Liver, kidney, brain, as lecithin or sphingomyelin

Question 5

Excretion route of choline?

Answer 5

With urine as trimethylamine (2/3 are metabolized by intestinal microorganims to this form) The rest is absorbed.

Question 6

Is there an other way of getting choline?

Answer 6

From phospholipids, catabolized from the membrane and the liver can also synthesize it de novo.

Question 7

Synthesis of choline in liver:

Answer 7

Serine –> (out CO2) ethanolamine –>(in CH3) methylethanolamine –> (in CH3) dimethyletanolamine –>(in CH3) Choline.

Question 8

Biochemical function of choline:

Answer 8

1. The formation from choline to lecithin and sphinomyelin , important for the cell mem. 2.Precursor of acetylcholine, needs acyltransferase. (synthesis) 3.Source of methyl groups for transmethylation. (synthesis) 4. As an lipotropic agent: removal of liver fat, fat and cholesterol accumulate in the liver very fast if choline is absent.

Question 9

What is a lipotropic agent?

Answer 9

Compounds that help catalyse the breakdown of fat during metabolism in the body.

Question 10

Deficiency of choline:

Answer 10

• Fatty liver -makes it hard for liver to function -Hemorragic kidney degradation, because of impairment in the phospholipid function of lysosomal membranes. -Most seen in poultry and pigs. When intake of other precursors or accessory factors, such as methionine, vit B12 or folic aci is insufficient, they require more choline. The microflora cannot synthesize.

Question 11

Inositol, structure:

Answer 11

Question 12

Characteristics of inositol:

Answer 12

-Water soluble -inactive -sweet -crystalline product -Myo-inositol is the only one with biological function.

Question 13

Metabolism of inositol

Answer 13

-Phytic acid is the dietary form. -Phytase splits inositol and phosphate, for absorption -can be produced by gut flora -In the liver of young animals glucose can be changed into inositol. -It can be metabolized as carbohydrates because it acts antiketogenically (inhibit fromation of ketones), it can be converted to glucose and the CO2 through PPP.

Question 14

Biochemical function of inositol:

Answer 14

• it is essential for fish, but not for mammals.(not a vitamin) -Lipotropic factors under special conditions with choline. -Phospholipid component in membranes. -Binds to hormones, releases Ca2+, neurotransmitters. -Inositol phosphatides is unsual, contains stearic acid and arachidonic acid, serves as a resevoir.

Question 15

Inositol deficiency:

Answer 15

Not for farm animals, get it from diet and bacteria. Rats in the lab can decrease their growth and get a fatty liver.

Question 16

Where do you find inositol?

Answer 16

Meat, whole grain, nuts, fruits, yeasts, bacteria. Often bound to phosphate as phytin.