An octanoic acid bridged with two sulfurs so that it is sometimes also called a pentanoic acid in some naming schemes. It is biosynthesized by cleavage of LINOLEIC ACID and is a coenzyme of oxoglutarate dehydrogenase (KETOGLUTARATE DEHYDROGENASE COMPLEX). It is used in DIETARY SUPPLEMENTS.
Lipoic acid is a vitamin-like antioxidant that acts as a free-radical scavenger. Alpha-lipoic acid is also known as thioctic acid. It is a naturally occurring compound that is synthesized by both plants and animals. Lipoic acid contains two thiol groups which may be either oxidized or reduced. The reduced form is known as dihydrolipoic acid (DHLA). Lipoic acid (Delta E= -0.288) is therefore capable of thiol-disulfide exchange, giving it antioxidant activity. Lipoate is a critical cofactor for aerobic metabolism, participating in the transfer of acyl or methylamine groups via the 2-Oxoacid dehydrogenase (2-OADH) or alpha-ketoglutarate dehydrogenase complex. This enzyme catalyzes the conversion of alpha-ketoglutarate to succinyl CoA. This activity results in the catabolism of the branched chain amino acids (leucine, isoleucine and valine). Lipoic acid also participates in the glycine cleavage system(GCV). The glycine cleavage system is a multi-enzyme complex that catalyzes the oxidation of glycine to form 5,10 methylene tetrahydrofolate, an important cofactor in nucleic acid synthesis. Since Lipoic acid is an essential cofactor for many enzyme complexes, it is essential for aerobic life as we know it. This system is used by many organisms and plays a crucial role in the photosynthetic carbon cycle. Lipoic acid was first postulated to be an effective antioxidant when it was found it prevented vitamin C and vitamin E deficiency. It is able to scavenge reactive oxygen species and reduce other metabolites, such as glutathione or vitamins, maintaining a healthy cellular redox state. Lipoic acid has been shown in cell culture experiments to increase cellular uptake of glucose by recruiting the glucose transporter GLUT4 to the cell membrane, suggesting its use in diabetes. Studies of rat aging have suggested that the use of L-carnitine and lipoic acid results in improved memory performance and delayed structural mitochondrial decay. As a result, it may be helpful for people with Alzheimer's disease or Parkinson's disease.
Top Gene Interactions
Paraoxonase (PON1) is a key enzyme in the metabolism of organophosphates. PON1 can inactivate some organophosphates through hydrolysis. PON1 hydrolyzes the active metabolites in several organophosphates insecticides as well as, nerve agents such as soman, sarin, and VX. The presence of PON1 polymorphisms causes there to be different enzyme levels and catalytic efficiency of this esterase, which in turn suggests that different individuals may be more susceptible to the toxic effect of OP exposure.
For nutritional supplementation, also for treating dietary shortage or imbalance.
- Health Effects: Acute exposure to cholinesterase inhibitors can cause a cholinergic crisis characterized by severe nausea/vomiting, salivation, sweating, bradycardia, hypotension, collapse, and convulsions. Increasing muscle weakness is a possibility and may result in death if respiratory muscles are involved. Accumulation of ACh at motor nerves causes overstimulation of nicotinic expression at the neuromuscular junction. When this occurs symptoms such as muscle weakness, fatigue, muscle cramps, fasciculation, and paralysis can be seen. When there is an accumulation of ACh at autonomic ganglia this causes overstimulation of nicotinic expression in the sympathetic system. Symptoms associated with this are hypertension, and hypoglycemia. Overstimulation of nicotinic acetylcholine receptors in the central nervous system, due to accumulation of ACh, results in anxiety, headache, convulsions, ataxia, depression of respiration and circulation, tremor, general weakness, and potentially coma. When there is expression of muscarinic overstimulation due to excess acetylcholine at muscarinic acetylcholine receptors symptoms of visual disturbances, tightness in chest, wheezing due to bronchoconstriction, increased bronchial secretions, increased salivation, lacrimation, sweating, peristalsis, and urination can occur. Certain reproductive effects in fertility, growth, and development for males and females have been linked specifically to organophosphate pesticide exposure. Most of the research on reproductive effects has been conducted on farmers working with pesticides and insecticdes in rural areas. In females menstrual cycle disturbances, longer pregnancies, spontaneous abortions, stillbirths, and some developmental effects in offspring have been linked to organophosphate pesticide exposure. Prenatal exposure has been linked to impaired fetal growth and development. Neurotoxic effects have also been linked to poisoning with OP pesticides causing four neurotoxic effects in humans: cholinergic syndrome, intermediate syndrome, organophosphate-induced delayed polyneuropathy (OPIDP), and chronic organophosphate-induced neuropsychiatric disorder (COPIND). These syndromes result after acute and chronic exposure to OP pesticides.
Symptoms of low dose exposure include excessive salivation and eye-watering. Acute dose symptoms include severe nausea/vomiting, salivation, sweating, bradycardia, hypotension, collapse, and convulsions. Increasing muscle weakness is a possibility and may result in death if respiratory muscles are involved. Hypertension, hypoglycemia, anxiety, headache, tremor and ataxia may also result.
If the compound has been ingested, rapid gastric lavage should be performed using 5% sodium bicarbonate. For skin contact, the skin should be washed with soap and water. If the compound has entered the eyes, they should be washed with large quantities of isotonic saline or water. In serious cases, atropine and/or pralidoxime should be administered. Anti-cholinergic drugs work to counteract the effects of excess acetylcholine and reactivate AChE. Atropine can be used as an antidote in conjunction with pralidoxime or other pyridinium oximes (such as trimedoxime or obidoxime), though the use of '-oximes' has been found to be of no benefit, or possibly harmful, in at least two meta-analyses. Atropine is a muscarinic antagonist, and thus blocks the action of acetylcholine peripherally.
Mechanism of Action
|Target Name||Mechanism of Action||References|
Eukaryotic translation initiation factor 4 gamma 1
SUMO-activating enzyme subunit 1
Sodium-dependent multivitamin transporter
Lipoyltransferase 1, mitochondrial
Lipoyl synthase, mitochondrial
|Lipoic Acid is generally involved in oxidative decarboxylations of keto acids and is presented as a growth factor for some organisms. Lipoic acid exists as two enantiomers, the R-enantiomer and the S-enantiomer. Normally only the R-enantiomer of an amino acid is biologically active, but for lipoic acid the S-enantiomer assists in the reduction of the R-enantiomer when a racemic mixture is given. Some recent studies have suggested that the S-enantiomer in fact has an inhibiting effect on the R-enantiomer, reducing its biological activity substantially and actually adding to oxidative stress rather than reducing it. Furthermore, the S-enantiomer has been found to reduce the expression of GLUT-4s in cells, responsible for glucose uptake, and hence reduce insulin sensitivity.||