Table 1.
Non-enzymatic antioxidant factors.
| Name | Type | Selected Comments/Examples | |
|---|---|---|---|
| Endogenous | GSH | H | Major cell ChAO (1–10 mM concentration) |
| α-Lipoic acid | H, L |
ROS scavenging Transition metal chelation |
|
| CoQ | L |
Inhibits lipid peroxidation Stabilizes ETC |
|
| Bilirubin | H |
From heme degradation Potent against peroxyl radicals |
|
| Uric acid | H |
From purine metabolism 2/3rd of plasma ROS scavenging |
|
| Melanins |
Family of pigment (photoprotective AO) Eyes, skin |
||
| Melatonin |
“Sleep hormone” (pineal gland) Inhibits lipid peroxidation. Increase AO enzymes In mitochondria: increases ETC and reduces electron leakage |
||
| Exogenous | Vit C * | H | L-Ascorbate Very low standard 1st reduction (−282 mV) |
| Vit A * | L |
Retinol, retinoic acid Membrane–bound. Inhibits lipid peroxidation (Scavenge peroxyl radicals, LOO°). |
|
| Vit E * | L |
α
-tocopherol Powerful membrane-bound AO Inhibits lipid peroxidation. Regenerated by ascorbic acid or CoQ. |
|
| Carotenoids | L |
Plant origin (e.g., Lycopene). Inhibits lipid peroxidation. (scavenge peroxyl radicals, LOO°) |
|
| Polyphenols | H, L |
Plant origin Flavonoids (e.g., Quercitin), Anthocyanins Strong inhibitors of lipid peroxidation |
|
|
Oligo-elements (Zn, Se) |
Na |
Competes with Fe and Cu (reduce OH° from H2O2) Protects SH groups from oxidation. Reduces the activities of iNOS and NADPH oxidase. Inhibits lipid peroxidation. |
*, as vitamins (related vitamin-type compounds showing similar biological activity). AO: antioxidant; H: hydrophilic; L: lipophilic; A: amphipathic; ETC: electron transfer chain; Na: not applicable.