Quasi vitamins, lipoic acid

1. Quasi vitamins: Lipoic acid
Domina Petric, MD

2. Coenzyme
• Lipoic acid (6-thiocytic acid) is an
essential cofactor for the
oxidative decarboxylations of
α-keto acids where, linked to the
ε-amino group of a lysine residue
of the enzyme dihydrolipoyl
transacetylase, it is one of several
prosthetic groups in the
multienzyme, lactate
dehydrogenase complex.
28.4.2018. Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.

3. Coenzyme
• In that catalysis, the amide
form, lipoamide, undergoes
reversible
acylation/deacylation to
transfer acyl groups to CoA
as well as reversible redox
ring opening/closing, which
is coupled with the oxidation
of the α-keto acid.
28.4.2018. Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.

4. Coenzyme
Lipoic acid occupies a
critical position in
energy metabolism,
regulating the flow of
carbon into the
tricarboxylic acid
cycle.
28.4.2018. Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.

5. Antioxidant
• The ability to undergo
interconversion between
disulfide (lipoic acid) and
sulfhydryl (dihydrolipoic
acid) forms enables lipoic acid
to function as a metabolic
antioxidant, quenching reactive
oxygen species and other free
radicals and chelating
prooxidant metal ions.
28.4.2018. Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.

6. Dietary sources
Lipoic acid is present in a wide
variety of foods at low levels.
The best sources are tissues
rich in mitochrondia (heart, kidney)
or chloroplasts (dark green leafy
vegetables such as spinach).
In these foods, most of the
factor appears to occur bound
to lysyl residues in proteins.
28.4.2018. Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.

7. Health effects
28.4.2018. Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.

8. Diabetes
Clinical trials with type II diabetic
subjects have found lipoic
acid treatment to:
• increase glucose clearance
• reduce blood glucose levels
and lipid peroxidation products
• reduce the severity of
cardiovascular neuropathy
28.4.2018. Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.

9. Multiple sclerosis
• A trial with patients with
multiple sclerosis indicated
that lipoic acid may be
useful in treatment by
reducing serum matrix
metalloproteinase-9 and
reducing T-cell migration
into the central nervous
system.
28.4.2018. Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.

10. Literature
• Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.
28.4.2018.