Table 1.
Antioxidant mechanisms and effects of natural compounds or extracts on SCI models.
| Compound or extract | Plant species | Origin | Effects on SCI models | Antioxidant mechanisms | References |
|---|---|---|---|---|---|
| From leaves | |||||
| Asiatic acid (AA) | Centella asiatica | China | Improves scores in locomotion tests Anti-inflammatory and antioxidant properties |
Increases SOD activity and GSH content | [41–44] |
| Ligustilide (LIG) |
Radix angelicae sinensis
Ligusticum chuanxiong |
China | Neuroprotective, cardiovascular, anti-inflammatory, and antioxidant effects | Scavenger, significantly suppresses iROS and iNOS expression Inhibits PLCγ and increases PI levels |
[49, 50] |
| Tetramethylpyrazine (TMP) | Ligusticum wallichii Franchat | China | Neuroprotective effects Anti-inflammatory properties |
Increases GSH levels and SOD activity, activates the Akt/Nrf2/HO-1 pathway | [55–60] |
| Epigallocatechin-3-gallate (EGCG) | Camellia sinensis (green tea) | China Japan Korea |
Improves motor function Relieves neuropathic pain Anti-inflammatory and antioxidant properties |
Increases GR and MDA levels and reduces myeloperoxidase and iNOS activity | [67, 68, 70, 77] |
| Ginsenosides | Panax ginseng C.A. Meyer | Asia | Neuroprotective effects Antioxidant properties |
Enhances the Nrf2/Ho-1 pathway and antioxidant proteins, decreases COX-2 and iNOS expression | [80–85] |
| Panax notoginsenoside (PNS) | Panax notoginseng (sachi ginseng) | China Burma Nepal |
Anti-inflammatory, antioxidant, neuroprotective, and antiapoptotic effects | Activation of Nrf2 and upregulation of downstream antioxidant systems, including HO-1 and GSTP1 | [93, 96, 99, 100] |
| Ginkgo biloba extract 761 (EGb-761) | Ginkgo biloba | China | Neuroprotective effects Anti-inflammatory and antioxidant properties |
Scavenger, inhibits xanthine oxidase and iNOS activity, reduces superoxide anion with SOD activity | [112–129] |
| Hyperforin | Hypericum perforatum (St. John's wort) | Europe Asia Africa |
Antioxidant properties Antiapoptotic effects |
Decreases G-Px values, inhibits NADPH-dependent lipid peroxidation, and attenuates nonenzymatic Fe2+/ascorbate-dependent lipid peroxidation | [133–139] |
| Rosmarinic acid (RA) | Lamiaceae family (rosemary, sage, lemon balm, and thyme) | India | Anti-inflammatory and antioxidant properties | Scavenger, upregulation in Nrf-2 levels with the concomitant increase in antioxidant enzymes (SOD, CAT, G-Px, GST, and GSH) | [140–143] |
| Carnosol | Rosmarinus officinalis L | Worldwide | Anti-inflammatory and antioxidant properties | Upregulates p-AKT and Nrf-2 expression | [144] |
| Silymarin (SM), silybin | Silybum marianum (milk thistle) | Mediterranean diet North Africa |
Induce effective functional, recovery Antioxidant properties |
Scavenger, inhibits ROS production enzymes, activates antioxidant enzymes via transcription factors (Nrf2 and NF-κB) | [146, 147] |
| From roots or bulbs | |||||
| Plumbagin | Plumbago zeylanica L | India and Ceylon | Anti-inflammatory and antioxidant properties | Activates the Nrf2/ARE pathway by which antioxidant enzymes are increased | [150, 151] |
| Tetrandrine (TET) | Stephania tetrandrae S | China | Protection against hypoxic/ischemic injury | Scavenger, blocks iNOS and COX-2 expression | [154–157] |
| Puerarin | Radix Puerariae lobata | China Worldwide |
Anti-inflammation and antiapoptotic properties | Increases TRX-1/TRX-2 mRNA levels and the activity of the PI3K/Akt signaling pathway | [159–164] |
| Allicin | Allium sativum (garlic) | Asia | Improves scores in locomotion tests Inhibition of oxidative stress |
Reduces iNOS protein expression levels, enhances NADH levels | [167–170] |
| Curcumin | Curcuma longa (turmeric) | India China Southeast Asia |
Antioxidant and anti-inflammatoryproperties | Scavenger, restores mitochondrial membrane potential, upregulates Cu-Zn SOD, improves GSH levels, inhibits iNOS expression by suppressing NF-κB signaling pathway, and activates transcription factors AP-1 and Nrf2 | [171–173] |
| From fruits | |||||
| Quercetin | Apples, berries, onions, broccoli, red grapes, and caper | America Europe Asia Africa |
Exerts neuroprotection Promotes locomotor function recovery Axonal regeneration |
Scavenger of ROS and reactive nitrogen species | [177–184] |
| Tocotrienols | Certain cereals, palm oil, rice bran oil, coconut oil, barley germ, wheat germ and annatto, grape seed oil, oat, hazelnuts, maize, olive oil | America Europe Asia Africa Oceania |
Improves scores in locomotion tests Anti-inflammatory and antioxidant properties |
Scavenger, inhibits iNOS protein expression and activity | [38, 193, 194] |
| Resveratrol | Polygonum cuspidatum, red wine, red grape skins, berries, blueberries, and peanuts | China Japan Korea America Europe Africa |
Improved scores in locomotion tests Increased number of neurons Antioxidant properties Antiapoptotic effects |
Increases activation of antioxidant enzymes such as SOD and antioxidant compounds such as GSH, induces HO-1 expression | [196–199] |
| Other extracts | |||||
| Sesquiterpenoids, flavonoids, phenols | Tithonia diversifolia | Africa Asia |
Neuroprotection Antioxidant properties |
Scavenger | [216] |
| Salvianolic acid B (Sal B), 3,4-dihydroxyphenyl lactic acid (DLA), tanshinone IIA (TIIA) | Salvia miltiorrhiza Bunge (Danshen) | China | Neuroprotection Antioxidant properties Antiapoptotic effects BSCB integrity regulation |
Increases SOD expression, upregulates the expression of HO-1, decreases myeloperoxidase activity | [220–227] |
SOD: superoxide dismutase; GSH: glutathione; iROS: intracellular reactive oxygen species; iNOS: inducible nitric oxide synthase; PLCγ: phospholipase Cγ; PI: phosphoinositol; GR: glutathione reductase; MDA: malondialdehyde; HO-1: heme oxygenase-1; GSTP1: glutathione S-transferase P1; G-Px: glutathione peroxidase; CAT: catalase; GST: glutathione transferase; TRX: thioredoxin; BSCB: blood-spinal cord barrier.