Neuroinflammation plays a central role in the pathogenesis and progression of various neurodegenerative disorders, including Alzheimer and Parkinson diseases, which affect millions worldwide. The brain’s innate immune cells, microglia, are critical regulators of neuroinflammatory responses (Adamu et al., 2024). Upon exposure to inflammatory stimuli such as bacterial endotoxins and microglia, they undergo activation and polarization toward a pro-inflammatory M1 phenotype, releasing cytokines as well as reactive oxygen species. This inflammatory environment disrupts neuronal homeostasis, promotes oxidative stress and accelerates neuronal apoptosis, contributing to neurodegeneration (Wendimu and Hooks, 2022).
       
Lipopolysaccharide (LPS), a major component of the outer membrane of gram-negative bacteria, is widely used for the induction of neuroinflammation. LPS triggers microglial activation and inflammatory mediator release, primarily through Toll-like receptor 4 (TLR4) signaling. This activation shifts microglia toward the M1 phenotype and this leads to suppressing M2, thereby making oxidative damage and apoptotic pathways (Batista et al., 2019).
       
Natural polyphenolic compounds, such as flavonoids, have demonstrated significant neuroprotective potential by modulating oxidative stress and inflammatory pathways. Galangin (3,5,7-trihydroxyflavone), a flavonoid derived from Alpinia officinarum, which has been utilized in China for centuries as a spice and in traditional medicine (Yao et al., 2024). This compound is recognized for its extensive variety of bioactivities, influencing multiple cellular functions. These consist of antioxidant, anti-inflammatory, antiulcer, antidiabetic, anticoagulant and anti-apoptotic effects observed in vitro and in animal studies (Supawat et al., 2024). Although its bioactivities are recognized, the effect of galangin on brain damage related to stroke has not been extensively researched. In this current research, the influence of galangin on brain infarct size, oxidative stress indicators, antioxidant defenses and the MAPK and Mfn2 pathways was investigated using an in vivo model of focal ischemic stroke (Palachai et al., 2025).
       
It also exhibits potent antioxidant and anti-inflammatory activities. It scavenges free radicals, inhibits NF-κB signaling and enhances endogenous cytoprotective mechanisms. These properties suggest galangin as a promising candidate for mitigating LPS-induced neurotoxicity (Scarlata et al., 2025).  However, despite these promising pharmacological properties, the potential of galangin to simultaneously modulate neuroinflammation, monoamine dysregulation, oxidative stress and apoptosis in LPS-induced brain injury remains insufficiently investigated.
       
The study’s main goals were to assess important variables and identify the processes underlying galangin protective effects, such as how it affects inflammation, oxidative stress and brain tissue apoptosis induced by LPS injection.

Study location and experimental period
 
The experimental work was conducted during 2025 at the Department of Zoology, Faculty of Science, Helwan University, Cairo, Egypt.
 
Chemicals and reagents
 
Galangin (≥98% purity) and lipopolysaccharide (LPS; Escherichia coli O111:B4) were obtained from Sigma-Aldrich (St. Louis, MO, USA). All reagents used were of analytical grade.
 
Animals
 
Forty adult male albino rat (120-125 g) were procured from VACSERA (Cairo, Egypt) and housed under standard laboratory conditions (12-hour light/dark cycle, 23±2°C, 50±10% humidity).
 
Experimental design
 
Induction of inflammation in rat and experimental design the inflammation was induced in rat by a single intraperitoneal injection (i.p.) of 2.5 mg/kg body weight of LPS (Boaru et al., 2012). Rats were randomly assigned to Four groups (n=10 each): Control group: Rats received saline. Galangin group: Rats received galangin (100 mg/kg/day, i.p.) for 21 days. The dosage of galangin was selected based on a previous study by Tomar et al., (2017). LPS group: Rats received a single dose of LPS (2.5 mg/kg, i.p.) on day 21. Galangin + LPS group: Rats pre-treated with galangin for 21 days then injected with one single dose of LPS (2.5 mg/kg, i.p.).
       
Twenty-four hours after lipopolysaccharide (LPS) administration, the rats were sacrificed by sudden decapitation. The brains were immediately removed and the hypothalamic region was carefully dissected, weighed, rinsed with ice-cold saline and homogenized in ice-cold 10 mM phosphate buffer (pH 7.4) to prepare a 10% (w/v) homogenate for subsequent biochemical analyses. The total protein concentration in the hypothalamic homogenate was determined using the Lowry method (Lowry et al., 1951).
 
Determination of monoamines and monoamine oxidase activity
 
Monoamines (dopamine and norepinephrine) were quantified in hypothalamic tissues using HPLC following Pagel et al., (2000), with CHROMABOND NH2 column (Cat. No. 730031) and AQUA C18 column (Phenomenex, USA). Monoamine oxidase (MAO) activity was determined fluorometrically following Dar et al., (2005).
 
Assessment of oxidative stress and antioxidant status
 
Lipid peroxidation (MDA) and nitric oxide (NO) levels were measured according to Ohkawa et al., (1979) and Green et al., (1982), respectively. 8-hydroxy-2-deoxyguanosine (8-OHdG) was measured as Lodovici et al., (1997). Antioxidant activities of glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) were evaluated according to Ellman (1959), Aebi (1984), Nishikimi et al., (1972), Paglia and Valentine (1967) and De Vega et al. (2002), respectively.
 
Determination of inflammatory and neurotrophic markers
 
Brain levels of TNF-α, IL-6 and IL-1β were assayed using ELISA kits (R and D Systems, Minneapolis, MN, USA) following the manufacturer instructions. Brain-Derived Neurotrophic Factor (BDNF) was also quantified by ELISA in accordance with the protocol described by Karege et al., (2002).
 
Determination of apoptotic markers
 
Apoptotic proteins including caspase-3 (colorimetric assay; Sigma-Aldrich, USA), Bcl-2 and Bax (ELISA kits; LifeSpan BioSciences, Seattle, WA, USA) were determined by manufacturer protocols. Results were normalized to tissue protein content (ng/mg).
 
Statistical analysis
 
Data were expressed as mean±SEM. Statistical comparisons between groups were carried out using one-way ANO VA followed by Duncan post hoc test using SPSS version 20.0 (IBM Corp.). A p value<0.05 was considered statistically significant.

Intraperitoneal administration of LPS (2.5 mg/kg, i.p.) to adult rats elicited significant neuroinflammatory and neurodegenerative alterations compared to the control group. These changes were evidenced by disturbances in neurotransmitter levels, enhanced oxidative stress, increased proinflammatory cytokine expression and activation of apoptotic pathways in brain tissue. Pretreatment with galangin (100 mg/kg/day, i.p.) for 21 days significantly attenuated these pathological alterations.
       
As shown in Fig (1), LPS administration resulted in a marked reduction in brain levels of dopamine (DA) and norepinephrine (NE) as compared to the control group (p<0.001). Additionally, a significant increase in monoamine oxidase (MAO) activity was observed. Treatment with galangin alone did not alter neurotransmitter levels significantly. However, pre-treatment of galangin in animals before LPS induction caused significantly restored DA and NE levels and reduced MAO activity as compared to the LPS group (p<0.01) (Fig 1).


       
The primary objectives of the study were to evaluate key variables and determine the mechanisms behind galangin protective effects, including its influence on neurotoxicity triggered by LPS injection. Through processes associated with neuroinflammation and oxidative stress, lipopolysaccharide (LPS) injection significantly alters the physiological and biochemical pathways of monoamine oxidase (MAO), dopamine (DA) and norepinephrine (NE) within neurons (Beucher et al., 2024). In neurons, MAO is found on the outer mitochondrial membrane in two isoforms, MAO-A and MAO-B. These enzymes control the synaptic levels and turnover of monoamine neurotransmitters, including DA and NE, by catalyzing their oxidative deamination.  LPS exposure has been shown to increase MAO activity. This elevation leads to enhanced catabolism of DA and NE, contributing to their decreased availability in the synaptic cleft. Furthermore, the oxidative deamination reaction by MAO produces hydrogen peroxide (H₂O₂), a reactive oxygen species (ROS) that can diffuse across membranes and trigger oxidative stress and neuroinflammation. Elevated levels of H₂O₂ serve as a signaling molecule but also lead to cellular damage, lipid peroxidation and the activation of inflammatory pathways (Wang et al., 2013).
       
Dopaminergic and noradrenergic neurons show sensitivity to neuroinflammatory damage caused by LPS. LPS triggers the activation of microglia and prompts the release of proinflammatory cytokines (such as TNF-α and IL-1β), which can impair dopamine production and contribute to neuronal dysfunction. The rising activity of MAO increases the breakdown of dopamine and norepinephrine, lowering their synaptic availability and disrupting neurotransmission. This decrease in DA and NE is associated with the behavioral and motor challenges found in neurodegenerative disorders (Beucher et al., 2024).
       
BDNF levels were significantly decreased in the LPS group compared to controls (p<0.001), reflecting impaired neuronal viability and function (Fig 2). Notably, galangin treatment significantly elevated BDNF expression in LPS + galangin groups, suggesting neuroprotective and trophic effects. Galangin, a natural flavonoid primarily found in Alpinia officinarum, has attracted considerable interest because of its diverse neuropharmacological properties. Its beneficial properties, characterized by strong antioxidant and anti-inflammatory actions, play an essential role in modulating brain neurotransmitter systems, especially dopamine and norepinephrine. Galangin affects key physiological and biochemical mechanisms in the central nervous system. It inhibits monoamine oxidase (MAO), the enzyme responsible for breaking down monoamines, maintaining synaptic levels of dopamine and norepinephrine, thereby supporting neuronal communication (Khawaja et al., 2024).


       
Furthermore, galangin capacity to scavenge reactive oxygen species and decrease the production of proinflammatory cytokines helps safeguard neuronal integrity against oxidative and inflammatory damage (Long et al., 2023; Palachai et al., 2025). Through these pathways, galangin not only stabilizes neurotransmitter levels but also mitigates the neurotoxic events linked to neuroinflammation, confirming its potential therapeutic applications in neurodegenerative conditions. In this study, administering galangin before LPS exposure led to a significant restoration of dopamine (DA) and norepinephrine (NE) concentrations in cerebral tissue (Chen et al., 2022).
       
LPS injection induced a significant elevation in malondialdehyde (MDA) levels, indicating enhanced lipid peroxidation (Fig 3), along with a marked reduction in antioxidant defenses, including GSH, SOD and CAT levels (Fig 4). These findings confirm oxidative damage in the brain tissue. Galangin treatment significantly ameliorated these oxidative disturbances by lowering MDA levels and restoring antioxidant enzyme activities close to normal values as compared to the LPS group (p<0.01). Galangin, a natural flavonoid primarily found in Alpinia officinarum, has attracted considerable interest because of its diverse neuropharmacological properties. Its beneficial properties, characterized by strong antioxidant and anti-inflammatory actions, play an essential role in modulating brain neurotransmitter systems, especially dopamine and norepinephrine. Galangin affects key physiological and biochemical mechanisms in the central nervous system. It inhibits monoamine oxidase (MAO), the enzyme responsible for breaking down monoamines, maintaining synaptic levels of dopamine and norepinephrine, thereby supporting neuronal communication (Khawaja et al., 2024).





In addition, LPS injections resulted in significant decrease in BDNF levels in brain tissue. The noted decrease in BDNF levels after LPS exposure aligns with earlier reported models of neuroinflammation triggered by endotoxins. BDNF is an essential neurotrophin that plays a key role in supporting neuronal survival, differentiation and synaptic plasticity. LPS-induced systemic inflammation interferes with this pathway by activating Toll-like receptor 4 (TLR4) on microglia, which triggers NF-κB activation and the following release of proinflammatory cytokines like IL-1β, IL-6 and TNF-α. These cytokines are known to inhibit BDNF gene expression and disrupt TrkB signaling, leading to synaptic dysfunction and neuronal apoptosis (Lee et al., 2020).
       
Galangin therapy significantly elevated BDNF levels in rats subjected to LPS, emphasizing its neurotrophic and neuroprotective abilities. The increase in BDNF levels due to galangin could be linked to its antioxidant and anti-inflammatory effects, which lessen neuroinflammation and facilitate the restoration of neurotrophic signaling. Additionally, galangin might directly stimulate CREB (cAMP response element-binding protein), which is a transcription factor that enhances BDNF gene expression. Increased BDNF availability aids neuronal recovery, boosts synaptic resilience and reduces the behavioral and cognitive impairments usually linked to neuroinflammatory disorders. These results are consistent with research showing that polyphenolic compounds can maintain or enhance BDNF signaling in neurodegeneration models, indicating a potential mechanism by which galangin provides neuroprotection (Abd El-Aal et al., 2022; Barua et al., 2022).
       
Oxidative stress is a key feature of neurotoxicity induced by LPS and is marked by overproduction of reactive oxygen species (ROS), resulting in lipid peroxidation, protein oxidation and fragmentation of DNA (Jain and Shakkarpude, 2024). In the present study, the treatment with LPS significantly increased malondialdehyde (MDA) levels, a product of lipid peroxidation, while greatly reducing endogenous antioxidants such as reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) (Dash et al., 2025). The disparity between ROS generation and antioxidant protection undermines neuronal integrity, encourages mitochondrial impairment and triggers the activation of redox-sensitive transcription factors like NF-κB and AP-1, which in turn intensify the inflammatory reaction. On the other hand, Galangin treatment successfully directed these oxidative imbalances (Schieber and Chandel, 2014).
       
The polyphenolic structure of the flavonoid allows for direct ROS scavenging by providing hydrogen atoms to free radicals, thereby neutralizing their reactivity. Additionally, galangin promotes the nuclear translocation of Nrf2 (nuclear factor erythroid 2-related factor 2), which is a key regulator of antioxidant defense. By activating Nrf2, galangin reestablishes redox balance and protects against ROS-induced damage to lipids, proteins and organelles. The recovery of antioxidant enzyme functions also aids in the preservation of mitochondria, since oxidative stress significantly promotes the decline of mitochondrial membrane potential and the discharge of pro-apoptotic elements (Zahra et al., 2024).
       
Brain tissue analysis showed a significant elevation in the levels of proinflammatory cytokines IL-1β, IL-6, TNF-α and the transcription factor NF-κB in the LPS-treated group (Fig 5) compared to control (p<0.001). Galangin treatment markedly suppressed the expression of these inflammatory mediators, indicating its potent anti-inflammatory potential in all studied parameters as compared to LPS treated group. LPS acts as a potent stimulator of innate immune responses in the brain, primarily through the activation of microglial cells. This activation triggers intracellular signaling cascades that include the mobilization of NF-κB, a key regulator of inflammatory responses. The activation of NF-κB leads to increased production and release of proinflammatory cytokines such as IL-1β, IL-6 and TNF-α. These mediators contribute to elevated oxidative stress, disruption of blood-brain barrier integrity, impaired synaptic function and neuronal damage. Collectively, these physiological alterations intensify neuroinflammation and promote neurotoxicity (Lively and Schlichter, 2018).


       
Galangin administration resulted in a marked suppression of neuroinflammatory responses, reflecting its potent anti-inflammatory and neuroprotective properties. These effects are largely attributed to its unique structure, particularly the presence of multiple hydroxyl groups, which confer strong antioxidant activity and enable modulation of intracellular signaling. The cascade begins with the inhibition of NF-κB activation, a central coordinator of inflammatory signaling (Palachai et al., 2025). By stabilizing intracellular pathways and preventing NF-κB translocation, galangin effectively reduced the activation of microglial cells. This was followed by a significant decrease in the production and release of key proinflammatory cytokines, including IL-1β, IL-6 and TNF-α. And this explains our present results (Shu et al., 2014).
       
Apoptotic indicators Bax and Caspase-3 levels (Fig 6) were significantly higher in the LPS group than in the control group. However, the Bcl2 levels were considerably lower (p<0.05). When compared to the LPS group, the intraperitoneal injection of galangin (100 mg/kg) returned the values of both apoptotic and antiapoptotic markers closer to the control group. Apoptosis is a crucial later event in neuroinflammatory damage, where the intrinsic (mitochondrial) pathway holds a primary significance. Our findings demonstrated that, LPS exposure markedly increased pro-apoptotic markers Bax and caspase-3 while reducing the anti-apoptotic protein Bcl-2, suggesting activation of the mitochondrial death pathway. Bax facilitates the permeabilization of the mitochondrial outer membrane (MOMP), leading to the release of cytochrome c and the formation of the apoptosome, which triggers the activation of caspase-9 and subsequent effector caspase-3. This sequence ultimately results in DNA fragmentation, collapse of the cytoskeleton and the death of neurons (Liu et al., 2023).


       
Galangin pre-treatment reestablished the Bax/Bcl-2 balance and inhibited caspase-3 activation, indicating a significant anti-apoptotic effect. Mechanistically, galangin may enhance the PI3K/Akt signaling pathway, which supports cell survival by blocking pro-apoptotic proteins and increasing Bcl-2 expression. Akt activation additionally phosphorylates and deactivates parts of the apoptotic machinery, such as Bad and caspase-9 (Xiong et al., 2020). Additionally, galangin antioxidant and anti-inflammatory characteristics provide indirect protection against apoptosis by decreasing oxidative stress and cytokine-induced mitochondrial impairment. Galangin supports neuronal survival against inflammatory damage by maintaining mitochondrial integrity and inhibiting apoptotic signalling (Palachai et al., 2025).

In summary, this current research shows that galangin has considerable neuroprotective properties against neuroinflammation and neurotoxicity triggered by LPS. These protective measures are facilitated by their capacity to influence critical neurochemical and molecular routes, which involve inhibiting monoamine oxidase activity, restoring levels of dopamine and norepinephrine, boosting antioxidant defenses, reducing proinflammatory cytokines and decreasing neuronal apoptosis. Additionally, the increased levels of brain-derived neurotrophic factor (BDNF) underscore its significance in enhancing neuronal survival and plasticity. These results establish galangin as a potentially effective natural treatment for preventing or alleviating neurodegenerative and neuropsychiatric conditions associated with systemic inflammation and oxidative stress.

The present study was supported by Princess Nourah bint Abdulrahman University Researchers Supporting Project number (PNURSP2026R39), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia.
 
Disclaimers
 
The views and conclusions expressed in this article are solely of the authors and do not necessarily represent the views of our affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.
 
Informed consent
 
All animal procedures of these experiments were approved by the Committee of Experimental Animal Care and handling techniques were approved by the University of Animal Care Committee. By the National Institutes of Health (NIH) Guidelines for the Care and Use of Laboratory Animals, 8th edition, all protocols and animal handling at the Department of Zoology, Faculty of Science, Helwan University were approved by the Committee on Research Ethics for Laboratory Animal Care (Cairo, Egypt; approval no. HU2021/Z/RKA0921-01).

There are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.