Role of Flavonoids in Mitigating the Pathological Complexities and Treatment Hurdles in Alzheimer's Disease

The Role of Selected Flavonoids in Modulating Neuroinflammation in Alzheimer's Disease: Mechanisms and Therapeutic Potential

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, amyloid-β (Aβ) deposition, tau hyperphosphorylation, oxidative stress, and chronic neuroinflammation. Growing evidence highlights neuroinflammation-driven by microglial activation and pro-inflammatory cytokine release-as a key contributor to AD pathogenesis and progression. In the absence of effective disease-modifying therapies, attention has turned to natural compounds with multi-target potential. Flavonoids, a diverse class of plant-derived polyphenols, have demonstrated neuroprotective properties through antioxidant activity, modulation of neuroinflammatory pathways, and interference with both Aβ aggregation and tau pathology. This narrative review provides an integrative overview of current findings on the mechanisms of action of key flavonoids-such as quercetin, luteolin, and apigenin-in both preclinical and clinical models. Emphasis is placed on their effects on microglial polarization, oxidative stress reduction, mitochondrial support, and synaptic function enhancement. Moreover, flavonoids show synergistic potential when combined with standard pharmacotherapies, such as acetylcholinesterase inhibitors, and may offer broader cognitive benefits in patients with mild cognitive impairment (MCI). Despite these promising findings, significant challenges persist, including poor bioavailability, inter-individual variability, and limited long-term clinical data. This review identifies critical gaps in knowledge and outlines future directions, including targeted drug delivery systems, biomarker-guided personalization, and long-duration trials. Flavonoids thus emerge not only as promising neuroprotective agents but also as complementary candidates in the development of future multi-modal strategies for AD treatment.

Targeting dopaminergic neuronal death: Luteolin as a therapeutic modulator in Parkinson's disease

Understanding the convoluted roles of dopamine in brain function is supreme for elucidating the pathophysiology and the therapeutic approach of movement disorders. Of which, Parkinson's disease (PD) is a progressive neurological ailment characterized by disturbed motor and non-motor functions. Luteolin, a plant-derived flavonoid, exhibits neuroprotective properties through its antioxidant and anti-inflammatory effects. In this study, we evaluated the therapeutic potential of luteolin in a rotenone-induced Wistar rat model of PD. Results of behavior assessment showed that luteolin (25 mg/kg and 50 mg/kg i.p.) treatment for 28 days significantly and dose-dependently improved motor functions. Furthermore, biochemical analysis demonstrated that luteolin restored oxidative balance by elevating glutathione (GSH) levels and reducing nitrate content. Additionally, ELISA results indicated that luteolin modulated level of tumor necrosis factor-alpha (TNF-α) and Bax, thereby reducing inflammation and neuronal apoptosis. Moreover, dopamine levels were significantly increased in rat brain homogenate, corroborating the neuroprotective effects of luteolin. Histopathological analysis further confirmed dopaminergic neuronal preservation in the cortex. These findings suggest that luteolin may serve as a potential therapeutic candidate for PD by mitigating oxidative stress, neuroinflammation, and apoptosis.

3',4',7-trihydroxyflavone activates the CREB-BDNF axis and restores scopolamine-induced memory deficit in mice

Alzheimer's disease is a major neurodegenerative disorder that leads to dementia, yet specific treatments remain elusive. Although Albizzia julibrissin has been used in traditional oriental medicine to treat insomnia and disorientation by its anti-inflammatory properties, there are currently no studies in animal models. This study aims to identify potential therapeutic candidates for Alzheimer's disease by examining how 3',4',7-trihydroxyflavone (THF), isolated from Albizzia julibrissin stem bark, as a potential therapeutic candidate for Alzheimer's disease by examining memory recovery in a scopolamine-induced memory deficit mouse model. THF administration both orally and centrally in scopolamine-induced AD mice led to significant improvements in cognitive performance. Biochemical assays revealed restoration of cholinergic markers (ACh, AChE, ChAT) and an increase in BDNF levels in the hippocampus. Electrophysiological recordings confirmed that THF restored LTP reduced by scopolamine, indicating improved synaptic plasticity. These findings suggest that THF has the potential neuropharmacological agent to protect the brain from memory loss induced by Alzheimer's disease through enhancing cholinergic system activity and activating the CREB-BDNF signaling pathway in the hippocampus.

Unraveling the role of brain renin angiotensin system in vascular dementia: mechanisms and therapeutic perspectives

Dementia is a heterogeneous syndrome characterized by the progressive deterioration of various brain functions, severely impacting cognitive, emotional, and social abilities. According to a World Health Organization (WHO) report, dementia represents a pressing global health concern, with the number of affected individuals projected to triple by 2050. Among its various subtypes, vascular dementia (VD) stands as the second most common form, following Alzheimer's disease (AD). Despite ongoing efforts in drug development, no pharmaceutical entity has yet received approval from the U.S. Food and Drug Administration (FDA) for the treatment of VD. Emerging evidence underscores the critical involvement of the brain's Renin-Angiotensin System (RAS) in the pathogenesis of multiple neurodegenerative disorders, including VD. The intricate roles of RAS components include regulating vascular tone, neuronal growth and survival, regulating cerebral blood flow and endothelial dysfunction, increasing neuroinflammation (by increasing release of IL-1, IL-6, TNF-α, microglial activation), oxidative stress and destruction of BBB integrity, mainly through Angiotensin II type 1 (AT1) and type 2 (AT2) receptors, are of significant interest in the pathophysiology of VD. However, disruptions in these signaling pathways are believed to contribute substantially to the progression of VD. This review addresses the limitations of current therapeutic approaches for VD while emphasizing the untapped potential of RAS-targeted interventions. We systematically explore the neurophysiological mechanisms of brain RAS, their role in promoting neuronal health, and the factors that compromise these pathways, ultimately leading to cognitive decline. By elucidating these mechanisms and challenges, the review offers novel insights into designing innovative RAS-based therapeutic strategies, paving the way for effective clinical management of VD. This work aspires to stimulate further research and development in this underexplored yet promising domain.

Electronic States of Epigallocatechin-3-Gallate in Water and in 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (Sodium Salt) Liposomes

In this work, the spectroscopy of epigallocatechin-3-gallate (EGCG) and EGCG bonded to 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (sodium salt) (DPPG) lipid is studied both experimentally by combining high-resolution vacuum ultraviolet (VUV) photo-absorption measurements in the 4.0-9.0 eV energy range and by theoretical calculations using density functional theory (DFT) methodology. There is a good agreement between the experimental and theoretical data, and the inclusion of the solvent both implicitly and explicitly further improves this agreement. For all experimentally measured absorption bands observed in the VUV spectra of EGCG in water, assignments to the calculated electronic transitions are provided. The calculations reveal that the spectrum of DPPG-EGCG has an intense peak around 150 nm, which is in accordance with experimental data, and it is assigned to an electron transfer transition from resorcinol-pyrogallol groups to different smaller groups of the EGCG molecule. Finally, the increase in absorbance observed experimentally in the DPPG-EGCG spectrum can be associated with the interaction between the molecules.