Alpha – lipoic acid is a nutritional coenzyme that participates in the energy metabolism of proteins, carbohydrates and fats, with a particular role in blood glucose disposal. † It is also able to scavenge a number of free radicals. As a fat and water – soluble, sulfur – containing coenzyme, alpha – lipoic acid functions in the body as part of several multi – enzyme complexes located in the mitochondria. Alpha – lipoic acid is essential f or metabolizing carbohydrates, proteins, and fats, for the conversion of their energy into ATP. Two of these enzyme complexes, pyruvate dehydrogenase (PDH) and alpha – ketoglutarate dehydrogenase (KGDH) are part of the citric acid cycle (Krebs cycle), and a s such assume a central role for general energy production. Another lipoic acid containing enzyme complex, branched – chain keto – acid dehydrogenase (BCKADH), is involved in deriving energy from the branched chain amino acids, leucine, isoleucine, and valine . A related metabolic function of alpha – lipoic acid is its role in blood glucose disposal. This important coenzyme appears to be necessary for the normal transport of blood glucose into the cell. † This may be explained by its functions in the glucose – met abolizing enzymes, PDH and alpha – KGDH, but some researchers suspect a more direct role in cellular glucose uptake at the cell membrane. Years of research show alpha – lipoic acid with antioxidant properties , since it could exten d the actions of vitamin C and vitamin E in animals. † In addition, alpha – lipoic acid can regenerate glutathione. †
It is only recently, however, that the specific actions of alpha – lipoic acid in free radical quenching, metal chelation, and antioxidant regeneration have been investigated. Body cells and tissues are threatened continuously by damage caused by toxic free radicals and reactive oxygen species (e.g., peroxides) which are produced during normal oxygen metabolism, and by toxic agents in the environment. Free radicals, once formed, are capable of disrupting metabolic function and cell structure. When this occurs, additional free radicals are produced which, in turn, can result in cellular dysfunction .
Alpha – lipoic acid is unique because it is soluble in both water and lipids. This allows it to neutralize free radicals just about everywhere in the body, inside an d outside the cells. Due to its unique sulfur – containing structure, alpha – lipoic acid can scavenge several types of free radicals, such as the highly reactive hydroxyl, and singlet oxygen free radicals. It is also capable of suppressing the generation of free radicals in the first place, since alpha – lipoic acid chelates transition metals, such as iron and copper. A lpha – lipoic acid is involved in many different antioxidant functions in virtually all body tissues .