R-(+)-alpha-Lipoic acid
[CAS# 1200-22-2]

Identification

• Classification: Chemical reagent >> Organic reagent >> Aromatic acid
• Name: R-(+)-alpha-Lipoic acid
• Synonyms: (R)-(+)-1,2-Dithiolane-3-pentanoic acid
• Molecular Formula: C₈H₁₄O₂S₂
• Molecular Weight: 206.33
• CAS Registry Number: 1200-22-2
• EC Number: 638-752-2
• SMILES: C1CSS[C@@H]1CCCCC(=O)O

Properties

• Solubility: 100 mM (DMSO), 100mM (ethanol) (Expl.)
• Density: 1.2±0.1 g/cm³, Calc.^*
• Melting point: 60-62 °C (Expl.)
• Index of Refraction: 1.562, Calc.^*
• Boiling Point: 362.5±11.0 °C (760 mmHg), Calc.^*, 160-165 °C (Expl.)
• Flash Point: 173.0±19.3 °C, Calc.^*

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319-H335
• Safety Statements: P261-P305+P351+P338

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Acute toxicity	Acute Tox.	4	H302
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2A	H319
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Skin sensitization	Skin Sens.	1	H317

Discovery and Applications

R-(+)-alpha-lipoic acid, also known as R-alpha-lipoic acid, is the naturally occurring isomer of alpha-lipoic acid, a compound that plays a crucial role in mitochondrial bioenergetics. It is an organosulfur compound that acts as both a cofactor for mitochondrial enzymes and as a potent antioxidant. R-(+)-alpha-lipoic acid is distinct from the synthetic form of alpha-lipoic acid, which contains both R- and S-enantiomers (racemic mixture), with R-(+)-alpha-lipoic acid being considered the more bioactive form.

The discovery of alpha-lipoic acid dates back to the 1950s when it was identified as a cofactor in the mitochondrial pyruvate dehydrogenase complex. This complex is essential for energy production, as it converts pyruvate into acetyl-CoA, a crucial molecule for the Krebs cycle. Initially, alpha-lipoic acid was studied for its role in mitochondrial energy metabolism and its ability to support cellular respiration.

Over time, the antioxidant properties of R-(+)-alpha-lipoic acid became more widely recognized. It is capable of neutralizing reactive oxygen species (ROS) and regenerating other antioxidants, such as vitamins C and E, in the body. This has made R-(+)-alpha-lipoic acid of particular interest in the context of oxidative stress-related diseases and aging.

R-(+)-alpha-lipoic acid has been applied in various therapeutic contexts, particularly for the management of conditions associated with oxidative stress. One of its primary uses is in the treatment of diabetic neuropathy, a common complication of diabetes that involves nerve damage caused by high blood sugar levels. Clinical studies have shown that R-(+)-alpha-lipoic acid can improve symptoms of diabetic neuropathy, including pain, tingling, and numbness. This has led to its inclusion in the treatment protocols for this condition.

Beyond its use in diabetic neuropathy, R-(+)-alpha-lipoic acid has also been investigated for its potential in the treatment of neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease. Its antioxidant properties suggest it may help reduce oxidative damage in the brain, though more research is needed to fully understand its role in these conditions.

R-(+)-alpha-lipoic acid is also used in the field of dermatology, where it is sometimes included in skincare products for its antioxidant effects. It is believed to help protect the skin from oxidative damage caused by UV radiation and environmental pollutants, contributing to its potential in anti-aging formulations.

In conclusion, R-(+)-alpha-lipoic acid is a naturally occurring compound with significant biological activity, particularly as a cofactor in mitochondrial energy production and as a potent antioxidant. Its applications are well-established in the treatment of diabetic neuropathy and have been explored in the context of neurodegenerative diseases and dermatology. As a bioactive molecule, R-(+)-alpha-lipoic acid continues to be an important subject of research in the fields of medicine and health.

References

2000. Synthesis and characterization of selenotrisulfide-derivatives of lipoic acid and lipoamide. Proceedings of the National Academy of Sciences of the United States of America.
DOI: 10.1073/pnas.220426897

1998. From lipoic acid to multi-enzyme complexes. Protein Science: A Publication of the Protein Society.
DOI: 10.1002/pro.5560070125

2003. Effect of iron-sulfur cluster assembly proteins on the expression of Escherichia coli lipoic acid synthase. Protein Expression and Purification.
DOI: 10.1016/s1046-5928(02)00680-0