Table 4.
Terpenoid phytochemicals exerting neuroprotective activities in Alzheimer’s disease models.
| Phytochemical tested | Plant | Concentration/Dose tested | Disease model | NRF2-related mechanism | Other observed AD-related effects | Reference |
|---|---|---|---|---|---|---|
| Cycloastragenol | Astragalus mongolica or Astragalus membranaceus | • 20 mg/kg/day (p.o.) | • Aβ-induced AD mouse model | • Upregulation of NRF2 | • Upregulation of HO-1, p-TrKB, BDNF, NeuN, p-JNK, p-P-38 and p-ERK | (118) |
| Androghrapholide | Andrographis paniculata | • 1.25, 2.5, 5, 10, 20 and 40 μM | • Al(Mal)3-induced PC12 cells | • Increase of NRF2 expression and nuclear translocation | • Increase of p62 levels and nuclear translocation | (119) |
| Quinovic acid | Mitragyna rotundifolia | • 50 mg/kg in a saline solution (i.p.) • 0.5, 10, 30, 55, 70, 85, 100 and 115 μM |
• Aβ-induced AD mouse model • SH-SY5Y cells |
• Upregulation of NRF2/HO-1 pathway | • Decrease of p53 expression and cholesterol accumulation • Downregulation of gliosis, IL-1, NF-kB, BAX, cleaved caspase-3 and cytochrome C • Improvement of spatial learning and memory behaviors |
(120) |
| Astaxanthin |
Haematococcus pluvialis
Xanthophyllomyces dendrorhous Honeybee propolis Red-colored marine organisms |
• 5, 10, 15 mg/kg in DMSO for 6 weeks (p.o.) | • AlCl3.6H2O solution-induced AD rat model | • Upregulation of NRF2 | • Decreased Aβ1-42, BACE1, AChE, MAO, MDA • Increased miRNA-124, ACh, serotonin • Improved cognitive dysfunction |
(121) |
| 2-Butoxytetrahydrofuran and Palmitic acid | Holothuria scabra | • 1, 5 and 10 μg/ml | • C. elegans | • Upregulation of SKN-1/NRF2 pathway | • Upregulation of DAF-16/FOXO pathway | (123) |
p.o., per os; Aβ, β-amyloid; AD, Alzheimer’s disease; NRF2, nuclear factor erythroid 2-related factor 2; HO-1, heme oxygenase-1; p-TrKB, phosphorylated tropomyosin receptor kinase B; BDNF, brain derived neurotrophic factor; NeuN, Fox-3, Rbfox3, or Hexaribonucleotide Binding Protein-3; p-JNK, phosphorylated C-Jun terminal kinase; p-ERK, phosphorylated extracellular signal-related kinase; Al(Mal)3, aluminum maltolate; i.p., intraperitoneally; IL-1, interleukin-1; NF-kB, nuclear factor kappa B; BAX, bcl-2 associated X protein; DMSO, dimethyl sulfoxide; AlCl3, aluminum chloride; BACE1, beta-secretase 1; AChE, acetylcholinesterase; MAO, monoamine oxidase; MDA, malondialdehyde; ACh, acetylcholine; C. elegans, Caenorhabditis elegans; SKN-1, protein skinhead-1; FOXO, forkhead box protein O.