L-Carnitine and  -Lipoic Acid Improve Age-Associated Decline in Mitochondrial Respiratory Chain Activity of Rat Heart Muscle

During aging, some of the free radical scavenging systems are decreased (5,6), so that more free radicals escape, increasing the level of oxidative stress within the organelle. L-Carnitine is a conditionally essential nutrient synthesized from the amino acids lysine and methionine in the human liver, brain, and kidney, and it functions in the transport of activated fatty acids over the mitochondrial inner membrane in eukaryotes. Furthermore, lipoic acid inhibits age-related alterations in the expression of genes involved in the extracellular matrix, cellular structure, and protein turnover, and it lowers the expression of genes encoding major histocompatibility complex components (14) evidencing that supplementation with lipoic acid results in transcriptional alterations consistent with a state of reduced oxidative stress in the heart.