Flavonoids as Therapeutic Agents in Alzheimer’s and Parkinson’s Diseases: A Systematic Review of Preclinical Evidences

Table 1

Characteristics of studies inserted in the review.

Authors, year, country	Substance(s)	Disease	Animals, (strain/sex) n (per group)	Doses, route, administration, period	Preclinical models	Evaluated parameters
						Behavior	Biochemical/molecular
Wei et al., 2013 [36], China	(2S)-5, 2, 5-trihydroxy-7-methoxyflavanone (TMF)	Alzheimer’s	Mice (Kunming/NR) ()	4 or 8 mg/kg, i.p., 1 week	D-galactose	(i) Spatial learning and memory (Morris water maze test)	(i) Colorimetric assay: GSH and GSSG; (ii) ELISA: AP-1 and BDNF; (iii) Western blot: CREB and p-CREB
Mani et al., 2013 [37], India	Naringin	Alzheimer’s	Rats (W/M),	100 mg/kg, p.o., 21 days	Deltamethrin	(i) NR	(i) Agarose gel electrophoresis: DNA fragmentation; (ii) Biochemical: LDH, CK, AChE, SOD, CAT, GPx, GR, GSH, vitamin C, vitamin E, and lipid peroxidation level; (iii) Histological analysis; (iv) Native gel electrophoresis: SOD and CAT
Nakajima et al., 2013 [38], Japan	Nobiletin	Alzheimer’s	Rats (SAMP8/M)	10 or 50 mg/kg, i.p., unclear	Senescence-accelerated prone mouse (SAMP8) model	(i) Nonspatial memory (novel object test); (ii) Contextual and auditory fear memory (fear conditioning test); (iii) Emotional reactivity, anxiety (elevated plus maze test)	(i) Biochemical: MDA, protein carbonyl level, SOD, and GPx; (ii) HPLC: GSH and GSSG; (iii) Real-time RT-PCR: GPx1 and GPx4; (iv) Western blot: Aβ1–42, tau, p-tau, GPx1, and GPx4
Moghbelinejad et al., 2014 [39], Iran	Rutin	Alzheimer’s	Rats (W/M)	100 mg/kg, i.p., 3 weeks	Amyloid beta (Aβ1–42)	(i) Memory retrieval (passive avoidance apparatus test)	(i) Biochemical: MDA and total SH groups; (ii) Real-time RT-PCR: BDNF, ERK1, ERK2, and CREB1
Li et al., 2014 [40], Germany	Hesperidin	Alzheimer’s	Mice (APP/PS1–21/M),	100 mg/kg, p.o., NR	Transgenic APP/PS1–21 mouse model	(ii) Nesting behavior (nest building assay); (iii) Social behavior, degree of interaction (social interaction assay)	(i) Double immunostaining; (ii) Immunohistochemistry: Aβ, GFAP, TGF-β1, and Alzheimer precursor protein A4
Javed et al., 2014 [41], India	Hesperidin	Alzheimer’s	Mice (S/M), or	100 and 200 mg/kg, i.p, 15 days	Streptozotocin	(i) Spatial learning and memory (Morris water maze test)	(i) Biochemical: TBARS, GSH, AChE, ganglioside, and phospholipids; (ii) Immunohistochemistry: GFAP, NF-κB, iNOS, and COX-2
Walker et al., 2015 [42], USA	Epigallocatechin gallate	Alzheimer’s	Mice (TgCRND8 (Tg) and wild type (nTg)/M and F), , , or	50 mg/kg, p.o., 4 months	TgCRND8 amyloid precursor protein transgenic mice	(i) Acquisition experience (nest building); (ii) Locomotor activity and exploratory (open field test); (iii) Novelty-seeking and anxiety-like behaviors (light-dark box); (iii) Learning (Barnes maze)	(i) ELISA: Aβ1–42
Kou et al., 2016 [43], China	Dihydromyricetin	Alzheimer’s	Rats (SD/M),	100 and 200 mg/kg, p.o., 6 weeks	D-galactose	(i) Spatial learning and memory (Morris water maze test)	(i) Histological analysis; (ii) Real-time PCR: miR-34a; (iii) SA-β-gal staining; (iv) Western blot: caspase-3, Bcl-2, SIRT1, p53, p21, Atg7, LC3-II/LC3-I, GFAP, and mTOR
Ali et al., 2016 [44], Republic of Korea	Anthocyanins and anthocyanin-loadedPEG-AuNPs	Alzheimer’s	Mice (C57BL/M),	12 μg/g/day, p.o., 14 days	Amyloid beta (Aβ1–42)	(i) Spatial learning and memory (Morris water maze and Y-maze tests)	(i) Immunohistochemical Nissl and FJB staining; (ii) Immunofluorescence; (iii) Western blot: Aβ, BACE-1, SNAP23, synaptophysin, p-AMPARs, p-PI3K, p-Akt, p-GSK3β, p-tau, PSD95, caspase-3, Cyt c, Bax, Bcl2, and poly (ADP-ribose) polymerase-(PARP-1)
Ramalingayya et al., 2016 [45], India	Naringin and Rutin	Alzheimer’s	Rats (W/F),	50 and 100 mg/kg, p.o., 15 days	Donepezil and scopolamine	(i) Locomotor activity and time spent in the center zone (open field test); (ii) Nonspatial memory (object recognition task)	(i) Hematological
Chen et al., 2016 [46], China	Quercetin	Alzheimer’s	Mice (C57BL/6J/M), NR	30 mg/kg, p.o., NR	Cognitive disorders per high-fat diet (HFD)	(i) Spatial learning and memory (Morris water maze test)	(i) Immunohistochemisty: p-PERK, p-IRE1α, NLRP3, and p-tau; (ii) Light microscopy: CA1; (iii) Western blot: AMPK, p-AMPK, IRE1α, p-IRE1α, eIF-2α, p-IF-2α, TXNIP, NLRP3, GSK-3β, p-GSK-3βser9, tau, and p-tau
Song et al., 2017 [47], China	Silibinin	Alzheimer’s	Rats (SD/M), NR	25, 50, and 100 mg/kg, p.o., 28 days	Amyloid beta (Aβ25–35)	(i) Anxiety and locomotor activity (Elevated plus maze test); (ii) Spatial learning and memory ability (Morris water maze test); (iii) Learning and memory (novel object-recognition test); (iv) Memory (memory flexibility test)	(i) Biochemical: MDA and GSH; (ii) ELISA: IL-1β, IL-4; (iii) Flow cytometric analysis; (iv) Transmission electron microscopy; (v) Western blot: NF-κB, COX-2, iNOS, p53, and p-p53
Moreno et al., 2017 [48], Spain	Quercetin and quercetin-loadednanoparticles	Alzheimer’s	Rats (SAMP8/M),	Quercetin (25 mg/kg, p.o., 2 months); Quercetin-loaded nanoparticles (25 mg/kg every 48 hours, p.o., 2 months)	Senescence-accelerated prone mouse (SAMP8) model	(i) Locomotor activity (open field test); (ii) Motor coordination and balance (rotarod test); (ii) Exploratory motivation (marble burying test); (iii) Spatial memory and both the working and reference memory functions (Morris water maze test)	(i) Western blot: GFAP and CD11b
Godoy et al., 2016 [49], Chile	Quercetin	Alzheimer’s	Rats (B6.129S7-Sod2tm1Leb/J/NR), NR	50 mg/kg, two times a week, p.o., 4 weeks	Amyloid beta (Aβ25–35)	(i) NR	(i) Electrophysiology
Palle and Neerati, 2016 [50], India	Quercetin and quercetin nanoparticles	Alzheimer’s	Rats (W/M),	30 mg/kg, i.p., 8 days	Scopolamine	(i) Conditioning, avoidance responses (conditioned avoidance test); (ii) Learning, memory (rectangular maze test)	(i) Biochemical: MDA, GPx, AChE, and CAT; (ii) Histological analysis
Ahmad et al., 2016 [51], Republic of Korea	Fisetin	Alzheimer’s	Mice (C57BL/6N/M),	20 mg/kg, i.p., 2 weeks	Amyloid beta Aβ1–42	(i) Spatial memory and both the working and reference memory functions (Morris water maze test)	(i) FJB staining; (ii) Immunofluorescence: Aβ (B4), synaptophysin, PSD95, p-tau, GFAP, and Iba-1; (iii) Immunohistochemistry: caspase-3; (iv) Western blot: caspase-9, SYN, p-AMPAR1, p-CREB, p-CAMKII, p-PI3K, and p-Akt
Rehman et al., 2017 [52], Republic of Korea	Anthocyanins	Alzheimer’s	Rats (SD/M),	100 mg/kg, i.p., 7 weeks	D-galactose	(i) Spatial learning and memory (Morris water maze and Y-maze tests)	(i) Biochemical: ROS, MDA; (ii) Immunofluorescence: Aβ, 8-OxoG, p-JNK, GFAP, and Iba-1; (iii) Western blot: Aβ, BACE-1, RAGE, 8-OxoG, TNF-α, iNOS, p-JNK, Bax, Bcl2, PARP-1, syntaxin, synaptophysin, SNAP-23, p-CREB, GFAP, and Iba-1
Kim et al., 2017 [53], Republic of Korea	Anthocyanins alone and anthocyanin-loaded poly (ethylene glycol) gold nanoparticles (PEG-AuNPs)	Alzheimer’s	Mice (C57BL/6N/M),	10 mg/kg, i.v., 14 days	Amyloid β (Aβ1–42)	(i) NR	(i) ICP-AES; (ii) Immunofluorescence: GFAP, Iba-1, and RAGE; (iii) Nissl staining; (iv) TEM; (v) Western blot: Aβ, BACE-1, GSK3β, CDK5, tau, NF-κB, iNOS, p-JNK, Bcl2, Bax, Cyt c, FJB, COX-2, NOS3, IL-1β, and TNF-α
Sharma et al., 2016 [54], India	Quercetin	Alzheimer’s and Parkinson’s	Rats (W/M),	10 mg/kg, p.o., 12 weeks	Aluminum	(i) NR	(i) Biochemical: ROS, MnSOD; (ii) DNA isolation for DNA fragmentation; (iii) Electron microscopy analysis; (iv) Histological analysis; (v) Immunohistochemistry: MnSOD, c-c, and caspase-3; (vi) RT-PCR: MnSOD; (vi) Western blot: MnSOD, Cyt c, Bax, Bcl-2, p53, and caspase-3
Jeong et al., 2015 [55], Republic of Korea	Naringin	Epilepsy, Parkinson’s, and Alzheimer’s	Mice (C57BL/6/M) NR	80 mg/kg, i.p., 7 days	Kainic acid	(i) NR	(i) Immunohistochemical: NeuN and Iba-1; (ii) Light microscopy: CA1; (iii) Western blot: LC3B and TNFα
Lee et al., 2014 [56], Republic of Korea	Baicalein	Parkinson’s	Mice (C57B/6/M),	1 and 10 mg/kg (i.p.), 7 days	MPTP	(i) Motor coordination and balance (rotarod test)	(i) DAB immunostaining: TH; (ii) Double label immunostaining: TH, GFAP, and Iba-1; (iii) Histological analysis; (iv) Western blot: GFAP
Antunes et al., 2014 [57], Brazil	Hesperidin	Parkinson’s	Mice (C57 BL/6/F),	50 mg/kg, p.o., 28 days	6-OHDA	(i) Depression (Tail-suspension test); (ii) Spatial learning and memory (Morris water maze); (iii) Locomotor activity and time spent in the center zone (open field test)	(i) Biochemical: GSH, ROS, TRAP, SOD, CAT, GR, GPx, GST, DA, DOPAC, and HVA
Lou et al., 2014 [58], China	Naringenin	Parkinson’s	Mice (C57BL/6/F),	70 mg/kg, p.o., 4 days	6-OHDA	(i) Rotational behavior—numbers of rotations (apomorphine-induced circling behavior)	(i) HPLC-MS: DA, DOPAC, and HVA; (ii) Immunohistochemistry: TH; (iii) Western blot: Nrf2, HO-1, GCLM, GCLC, Lamin A, cleaved caspase-3, p-JNK, JNK, p-p38, and p38
Wang et al., 2015 [59], China	Tanshinone I	Parkinson’s	Mice (C57BL/6/M), NR	5, 10 mg/kg, p.o., 7 days	MPTP	(i) Motor coordination and balance (rotarod test)	(i) Biochemical: ALT, AST, and ALP; (ii) ELISA: TNF-α and IL-10; (iii) HPLC: DA, DOPAC, HVA, and MPP+; (iv) Immunohistochemistry: TH and Iba-1
Chen et al., 2015 [60], China	Silibilin	Parkinson’s	Rats (M and F), NR	25 and 50 mg/kg, p.o. in second day	Increased neonatal iron intake	(i) Locomotor activity and time spent in the center zone (open field test); (ii) Motor coordination and balance (rotarod test)	(i) Biochemical: MDA and GSH; (ii) HPLC-ECD: DA and 5-HT
Mu et al., 2016 [61], China	Quercetin	Parkinson’s	Rats (SD/M), NR	100, 200, and 400 mg/kg, i.g., NR	6-OHDA	(i) Rotational behavior—numbers of rotations (apomorphine-induced circling behavior)	(i) HPLC-ECD: DA, DOPAC, HVA, 5-HT, and 5-HIAA
Lee et al., 2015 [62], Korea	Silibinin	Parkinson’s	Mice (C57B/6/M), or 12	1 or 10 mg/kg, i.p., 5 days	MPTP	(i) Motor coordination and balance (rotarod test)	(i) DAB immunostaining: TH; (ii) Double label immunostaining: GFAP and Iba-1
Hu et al., 2016 [63], China	Baicalein	Parkinson’s	Mice (C57BL/6/M), NR	100 mg/kg, i.p., 7 weeks to 12 weeks	Rotenone	(i) Motor coordination and balance (rotarod test); (ii) Motor dysfunctions (grid test)	(i) HPLC: DA, DOPAC, and HVA; (ii) Immunofluorescence: α-syn, TH, and ChAT; (iii) Real-time PCR: α-syn; (iv) TEM; (v) Western blot: α-synuclein and GAPDH
Zhang et al., 2017 [64], China	Baicalein	Parkinson’s	Rats (SD/M), , or 10	100, 200, and 400 mg/kg, p.o., 28 days	Rotenone	(i) Locomotor activity (open field test); (ii) Motor coordination and balance (rotarod test); (iii) The inclined plane assessment	(i) Immunohistochemistry: TH; (ii) TEM; (iii) TUNEL staining; (iv) Western blot: caspase-3, PGC-1α, NRF-1, and TFAM
Goes et al., 2017 [65], Brazil	Chrysin	Parkinson’s	Mice (C57B/6J/M),	10 mg/kg, p.o., 28 days	6-OHDA	(i) Motor coordination and balance (rotarod test); (ii) Rotational behavior—numbers of rotations (apomorphine-induced circling behavior)	(i) ELISA: IFN-γ, TNF-α, IL-6, IL-10, NF-κB, S100B, BDNF, GDNF, and NGF; (ii) HPLC: DA, DOPAC, and HVA; (iii) TRAP and TAR; (iv) Immunohistochemistry: TH^+ neurons
Ay et al., 2017 [66], USA	Quercetin and quercetin-containingformulation (QB3C)	Parkinson’s	Mice (MitoPark and C57BL/6/M/F), or	Quercetin (25 mg/kg, p.o., 6 weeks); QB3C comprising quercetin (175 mg/kg, p.o., 8 weeks)	MitoPark transgenic mouse models	(i) Locomotor activity (open field test); (ii) Motor coordination and balance (rotarod test)	(i) HPLC: DA, DOPAC, and HVA; (ii) DAB immunostaining: TH

Animals: SD: Sprague-Dawley; W: Wistar; S: Swiss; SAMP8: senescence-accelerated prone mouse 8; NR: not reported. Parameters assessed: DPPH: 2,2-diphenyl-1-picrylhydrazyl radical; MDA: malonaldehyde; TBARS: thiobarbituric acid reactive substances; AAPH: 2,2-azobis(2-methylpropionamidine) dihydrochloride; FeSO4: ferrous sulphate; 6-OHDA: 6-hydroxydopamine; MPTP: 1-methyl-4-phenyl-1,2,3,4-tetrahydropyridine; FJB: Fluoro-Jade B; GSH: reduced glutathione; GSSG: oxidized glutathione; AP-1: activator protein-1; BDNF: brain-derived neurotrophic factor; CREB: cAMP response element-binding protein; p-CREB: phosphorylated; SOD: superoxide dismutase; CAT: catalase; GPx: glutathione peroxidase; GR: glutathione reductase; GSH: reduced glutathione; LDH: lactate dehydrogenase; CK: creatine kinase; AChE: acetylcholinesterase; MDA: malondialdehyde; p-tau: phosphorylated tau; TGF-β1: transforming growth factor beta 1; SYN: synaptophysin; p-AMPAR1: phospho-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors; p-CRE: phosphorylated cAMP response element binding protein; p-CAMKII: phosphorylated calcium/calmodulin-dependent protein kinase II; p-PI3K: phosphorylated phosphatidylinositol-4,5-bisphosphate 3-kinase; p-Akt: phosphorylated protein kinase B; GFAP: antiglial fibrillary acidic protein; Iba-1: anti-ionized calcium-binding adapter molecule 1; 8-OxoG: 8-oxoguanine; p-JNK: C-jun N-terminal kinase; ICP-AES: inductively coupled plasma-atomic emission spectrometer; TEM: transmission electron microscopy; Aβ: brain expression levels of amyloid beta; BACE-1: beta-site APP cleaving enzyme 1; GSK3β: glycogen synthase kinase-3β; CDK5: cyclin-dependent kinase 5; GFAP: glial fibrillary acidic protein; NF-κB: nuclear factor kappa B; iNOS: inducible nitric oxide synthase; COX-2; NOS3; IL-1β; TNF-α; p-JNK: phospho-JNK; Bcl2; Bax; Cyt c: cytochrome c; FJB. RAGE receptor for advanced glycation end products; MnSOD: mitochondrial superoxide dismutase; NeuN: neuronal nuclei; LC3B: microtubule-associated protein light chain 3 isoform B; MS: mass spectrometry; DA: dopamine; DOPAC: dihydroxyphenylacetic acid; HVA: homovanillic acid; HO-1: hemeoxygenase; Nrf2: nuclear factor E2-related factor 2; GCLC: glutathione cysteine ligase regulatory subunit; GCLM: glutathione cysteine ligase modulatory subunit; JNK: c-Jun N-terminal kinase; MPP+: 1-methyl-4-phenylpyridinium; ALT: alanine aminotransferase; AST: aspartate aminotransferase; ALP: alkaline phosphatase; HPLC: high-performance liquid chromatography; ECD: equipped with electro chemical detector; TRAP: total reactive antioxidant potential; TAR: total antioxidant reactivity; S100B: calcium-binding protein B; GDNF: glial cell line-derived neurotrophic factor; NGF: nerve growth factor; DAB: diaminobenzidine; SA-β-Gal: senescence-associated β-galactosidase.