Actions of melatonin in the reduction of oxidative stress

Abstract

Melatonin was discovered to be a direct free radical scavenger less than 10 years ago. Besides its ability to directly neutralize a number of free radicals and reactive oxygen and nitrogen species, it stimulates several antioxidative enzymes which increase its efficiency as an antioxidant. In terms of direct free radical scavenging, melatonin interacts with the highly toxic hydroxyl radical with a rate constant equivalent to that of other highly efficient hydroxyl radical scavengers. Additionally, melatonin reportedly neutralizes hydrogen peroxide, singlet oxygen, peroxynitrite anion, nitric oxide and hypochlorous acid. The following antioxidative enzymes are also stimulated by melatonin: superoxide dismutase, glutathione peroxidase and glutathione reductase. Melatonin has been widely used as a protective agent against a wide variety of processes and agents that damage tissues via free radical mechanisms.

Combination therapy with melatonin and dexamethasone in a mouse model of traumatic brain injury

“…The protective effects of melatonin were not limited to an overall anti-inflammatory effect, but included significant protection of injury, as well as the inhibition of key pro-inflammatory mediators (Reiter et al 1997). As an antioxidant, melatonin can directly scavenge free radicals while also acting indirectly to increase the expression of endogenous antioxidant enzymes (Reiter et al 2000), and may be superior to glutathione, mannitol, and vitamin E (Reiter et al 1997). Additionally, due to its amphiphilic structure, melatonin has no barriers to its distribution and may have the advantages of having a lower-side effect profile and producing fewer pharmacokinetic or pharmacodynamic interactions compared with xenobiotic antioxidants.…”

Protective effect of oat bran extracts on human dermal fibroblast injury induced by hydrogen peroxide

“…5c). It is well known that SOD serves as the first gatekeeper in the antioxidant defense system designed to scavenge superoxide anions (Reiter et al, 2000), while GSH-Px is a catalyzer that activates the reaction of lipid hydroperoxides with reduced glutathione to form glutathione disulfide (Venukumar and Latha, 2002). An avenanthramides (AVE)-enriched mixture extracted from oat was reported to increase human plasma GSH-Px activity by 30%-35% (Chen et al, 2007).…”

Prospects of N-Acetylcysteine and Melatonin as Treatments for Tramadol-Induced Renal Toxicity in Albino Rats

“…9 Studies have reported lipid peroxidation, mitochondria damage, inhibition of protein synthesis and decrease in antioxidants in the kidneys of TD-treated rats [10][11][12] Melatonin (MT), a hormone produced by the pineal gland, is a potent scavenger of reactive oxidative radicals. 13 Thus, MT can prevent free radicalinduced cellular oxidative damage and can contribute to the physiological functions of the antioxidant defensive system. 14 Also, it can stimulate several antioxidant systems, thereby facilitating more antioxidant activities and stabilizing cell membranes.…”