A comparison of melatonin and α-lipoic acid in the reduction of oxidative stress in L6 rat skeletal muscle cells

Aging is an universal, inevitable and multifactorial biological process, which causes progressive loss of function and an increased risk of death. Free radicals have been implicated in aging process, causing cumulative oxidative damage to crucial macromolecules and are responsible for failure of multiple physiological mechanisms [1]. Muscle mass and function are gradually lost during aging leading to neuromuscular disorders (such as fibromyalgia, sarcopenia, etc.). The indoleamine melatonin is able to prevent oxidative stress both through its free radical scavenging effect and by increasing endogenous antioxidant activity and so protecting against oxidative damage induced by drugs, toxins and different diseases [2]. Herein, we evaluated the susceptibility of rat L6 skeletal muscle cells to induced oxidative stress due to the exposure of cells to hydrogen peroxide and the potential protective effects of the pre-treatment with melatonin (MelapureTM by Flamma S.p.A.), compared to the known beneficial effect of alpha-lipoic acid. Our results showed that hydrogen peroxide-induced obvious oxidative stress, increasing the expression of tumour necrosis-alpha and in turn of nuclear factor kappa-B, overriding the endogenous defence mechanisms and alterating the mitochondrial structure. In contrast, the pre-treatment with melatonin of the hydrogen peroxide-exposed cells increased endogenous antioxidant enzymes, including superoxide dismutase-2 and heme oxygenase-1, and ameliorated significantly both the oxidative stress damage and the mitochondrial alterations, that are known to be involved in aging and aging related diseases. In conclusion, melatonin had important anti-oxidant and anti-aging effects at the level of skeletal muscle in vitro.