Abstract
The aim of the present study was to verify whether lipoic acid (LA) itself is a source of H2S and sulfane sulfur. It was investigated in vitro non-enzymatically and enzymatically (in the presence of rat tissue homogenate). The results indicate that both H2S and sulfane sulfur are formed from LA non-enzymatically in the presence of environmental light. These results suggest that H2S is the first product of non-enzymatic light-dependent decomposition of LA that is, probably, next oxidized to sulfane sulfur-containing compound(s). The study performed in the presence of rat liver and kidney homogenate revealed an increase of H2S level in samples containing LA and its reduced form dihydrolipoic acid (DHLA). It was accompanied by a decrease in sulfane sulfur level. It seems that, in these conditions, DHLA acts as a reducing agent that releases H2S from an endogenous pool of sulfane sulfur compounds present in tissues. Simultaneously, it means that exogenous LA cannot be a direct donor of H2S/sulfane sulfur in animal tissues. The present study is an initial approach to the question whether LA itself is a donor of H2S/sulfane sulfur.
Highlights
Lipoic acid (LA, 1,2-dithiolane-3-pentanoic acid) was first identified by Reed et al [1]
The results indicate that both H2S and sulfane sulfur are formed from lipoic acid (LA) non-enzymatically in
The results indicate that both H2 S and sulfane sulfur are formed from LA non-enzymatically in the the presence of environmental light
Summary
Lipoic acid (LA, 1,2-dithiolane-3-pentanoic acid) was first identified by Reed et al [1]. In mammals, it is synthesized in very small quantities in the liver and other tissues and is used as a cofactor of mitochondrial complexes catalyzing oxidative decarboxylation of alpha keto acids and glycine cleavage system (GCS) localized in mitochondria. It is synthesized in very small quantities in the liver and other tissues and is used as a cofactor of mitochondrial complexes catalyzing oxidative decarboxylation of alpha keto acids and glycine cleavage system (GCS) localized in mitochondria In these enzymatic complexes, LA is linked by an amide bound to the ε-amino group of a lysine residue of the protein. LA has become a common ingredient of different multivitamin formulas, dietary supplements and even pet food [2]
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