Experimental and Computational Studies to Characterize and Evaluate the Therapeutic Effect of Albizia lebbeck (L.) Seeds in Alzheimer's Disease

Protective effect of a hydromethanolic extract from Fraxinus excelsior L. bark against a rat model of aluminum chloride-induced Alzheimer's disease: Relevance to its anti-inflammatory and antioxidant effects

ETHNOPHARMACOLOGICAL RELEVANCE

Fraxinus excelsior L. (FE), commonly known as the ash, belongs to the Oleaceae family and has shown several pharmacological and biological properties, such as antioxidant, immunomodulatory, neuroprotective, and anti-inflammatory effects. It has also attracted the most attention toward neuroinflammation. Moreover, FE bark and leaves have been used to treat neurological disorders, aging, neuropathic pain, urinary complaints, and articular pain in traditional and ethnomedicine. Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder resulting from the involvement of amyloid-beta, metal-induced oxidative stress, and neuroinflammation.

AIM OF THE STUDY

The objective of the current study was to assess the neuroprotective effects of hydromethanolic extract from FE bark in an AlCl3-induced rat model of AD.

MATERIALS AND METHODS

The maceration process was utilized to prepare the hydromethanolic extract of FE bark, and characterized by LC-MS/MS. To assess the anti-AD effects of the FE extract, rats were categorized into five different groups, AlCl3; normal control; FE-treated groups at 50, 100, and 200 mg/kg. Passive avoidance learning test, Y-maze, open field, and elevated plus maze behavioral tests were evaluated on days 7 and 14 to analyze the cognitive impairments. Zymography analysis, biochemical tests, and histopathological changes were also followed in different groups.

RESULTS

LC-MS/MS analysis indicated the presence of coumarins, including isofraxidin7-O-diglucoside in the methanolic extract of FE as a new isofraxidin derivative in this genus. FE significantly improved memory and cognitive function, maintained weight, prevented neuronal damages, and preserved the hippocampus's histological features, as demonstrated by behavioral tests and histopathological analysis. FE increased anti-inflammatory MMP-2 activity, whereas it decreased that of inflammatory MMP-9. Moreover, FE increased plasma antioxidant capacity by enhancing CAT and GSH while decreasing nitrite levels in the serum of treated groups. In comparison between the treated groups, the rats that received high doses of the FE extract (200 mg/kg) showed the highest therapeutic effect.

CONCLUSION

FE rich in coumarins could be an effective anti-AD adjunct agent, passing through antioxidant and anti-inflammatory pathways. These results encourage further studies for the development of this extract as a promising agent in preventing, managing, or treating AD and related diseases.

Parkinson's disease model in zebrafish using intraperitoneal MPTP injection

Introduction

Parkinson's disease (PD) is the second most common neurodegenerative disease that severely affects the quality of life of patients and their family members. Exposure to 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been shown to reflect behavioral, molecular, and proteomic features of PD. This study aimed to assess the protocol for inducing PD following MPTP injection in adult zebrafish.

Methods

Fish were injected with 100 μg/g of MPTP intraperitoneally once or twice and then assessed on days 1 to 30 post-injection.

Results

Between one-time and two-time injections, there was no significant difference in most locomotor parameters, expressions of tyrosine hydroxylase-2 (th2) and dopamine transporter (dat) genes, and dopaminergic neurons (tyrosine hydroxylase positive, TH+ cells) counts. However, caspase-3 levels significantly differed between one- and two-time injections on the day 1 assessment.

Discussion

Over a 30-day period, the parameters showed significant differences in swimming speed, total distance traveled, tyrosine hydroxylase-1 (th1) and dat gene expressions, caspase-3 and glutathione protein levels, and TH+ cell counts. Days 3 and 5 showed the most changes compared to the control. In conclusion, a one-time injection of MPTP with delayed assessment on days 3 to 5 is a good PD model for animal studies.

Neuroprotective Effects of Albizia lebbeck (L.) Benth. Leaf Extract against Glutamate-Induced Endoplasmic Reticulum Stress and Apoptosis in Human Microglial Cells

Endoplasmic reticulum (ER) stress caused by excessive glutamate in the central nervous system leads to neurodegeneration. Albizia lebbeck (L.) Benth. has been reported to possess neuroprotective properties. We aimed to investigate the effect and mechanism of A. lebbeck leaf extracts on glutamate-induced neurotoxicity and apoptosis linked to ER stress using human microglial HMC3 cells. A. lebbeck leaves were extracted using hexane (AHE), mixed solvents, and ethanol. Each different extract was evaluated for cytotoxic effects on HMC3 cells, and then non-cytotoxic concentrations of the extracts were pretreated with the cells, followed by glutamate. Our results showed that AHE treatment exhibited the highest protective effect and was thus selected for finding the mechanistic approach. AHE inhibited the specific ER stress proteins (calpain1 and caspase-12). AHE also suppressed the apoptotic proteins (Bax, cytochrome c, cleaved caspase-9, and cleaved caspase-3); however, it also increased the antiapoptotic Bcl-2 protein. Remarkably, AHE increased cellular antioxidant activities (SOD, CAT, and GPx). To support the activation of antioxidant defense and inhibition of apoptosis in our HMC3 cell model, the bioactive phytochemicals within AHE were identified by HPLC analysis. We found that AHE had high levels of carotenoids (α-carotene, β-carotene, and lutein) and flavonoids (quercetin, luteolin, and kaempferol). Our novel findings indicate that AHE can inhibit glutamate-induced neurotoxicity via ER stress and apoptosis signaling pathways by activating cellular antioxidant enzymes in HMC3 cells, suggesting a potential mechanism for neuroprotection. As such, A. lebbeck leaf might potentially represent a promising source and novel alternative approach for preventing neurodegenerative diseases.

Extract of Aster koraiensis Nakai Leaf Ameliorates Memory Dysfunction via Anti-inflammatory Action

Aster koraiensis Nakai (AK) leaf reportedly ameliorates health problems, such as diabetes. However, the effects of AK on cognitive dysfunction or memory impairment remain unclear. This study investigated whether AK leaf extract could attenuate cognitive impairment. We found that AK extract reduced the production of nitric oxide (NO), tumour necrosis factor (TNF)-α, phosphorylated-tau (p-tau), and the expression of inflammatory proteins in lipopolysaccharide- or amyloid-β-treated cells. AK extract exhibited inhibitory activity of control specific binding on N-methyl-D-aspartate (NMDA) receptors. Scopolamine-induced AD models were used chronically in rats and acutely in mice. Relative to negative controls (NC), hippocampal choline acetyltransferase (ChAT) and B-cell lymphoma 2 (Bcl2) activity was increased in rats chronically treated with scopolamine and fed an AK extract-containing diet. In the Y-maze test, spontaneous alterations were increased in the AK extract-fed groups compared to NC. Rats administered AK extract showed increased escape latency in the passive avoidance test. In the hippocampus of rats fed a high-AK extract diet (AKH), the expression of neuroactive ligand–receptor interaction-related genes, including Npy2r, Htr2c, and Rxfp1, was significantly altered. In the Morris water maze assay of mice acutely treated with scopolamine, the swimming times in the target quadrant of AK extract-treated groups increased significantly to the levels of the Donepezil and normal groups. We used Tg6799 Aβ-overexpressing 5XFAD transgenic mice to investigate Aβ accumulation in animals. In the AD model using 5XFAD, the administration of AK extract decreased amyloid-β (Aβ) accumulation and increased the number of NeuN antibody-reactive cells in the subiculum relative to the control group. In conclusion, AK extract ameliorated memory dysfunction by modulating ChAT activity and Bcl2-related anti-apoptotic pathways, affecting the expression of neuroactive ligand–receptor interaction-related genes and inhibiting Aβ accumulation. Therefore, AK extract could be a functional material improving cognition and memory.

Anticholinesterase Activity of Budmunchiamine Alkaloids Revealed by Comparative Chemical Profiling of Two Albizia spp., Molecular Docking and Dynamic Studies

Alzheimer's disease remains a global health challenge and an unmet need requiring innovative approaches to discover new drugs. The current study aimed to investigate the inhibitory activity of Albizia lucidior and Albizia procera leaves against acetylcholinesterase enzyme in vitro and explore their chemical compositions. Metabolic profiling of the bioactive plant, A. lucidior, via UHPLC/MS/MS-based Molecular Networking highlighted the richness of its ethanolic extract with budmunchiamine alkaloids, fourteen budmunchiamine alkaloids as well as four new putative ones were tentatively identified for the first time in A. lucidior. Pursuing these alkaloids in the fractions of A. lucidior extract via molecular networking revealed that alkaloids were mainly concentrated in the ethyl acetate fraction. In agreement, the alkaloid-rich fraction showed the most promising anticholinesterase activity (IC₅₀ 5.26 µg/mL) versus the ethanolic extract and ethyl acetate fraction of A. lucidior (IC₅₀ 24.89 and 6.90 µg/mL, respectively), compared to donepezil (IC₅₀ 3.90 µg/mL). Furthermore, deep in silico studies of tentatively identified alkaloids of A. lucidior were performed. Notably, normethyl budmunchiamine K revealed superior stability and receptor binding affinity compared to the two used references: donepezil and the co-crystallized inhibitor (MF2 700). This was concluded based on molecular docking, molecular dynamics simulations and molecular mechanics generalized born/solvent accessibility (MM-GBSA) calculations.

The curative and mechanistic acumen of curcuminoids formulations against haloperidol induced Parkinson's disease animal model

Parkinson's disease (PD) is slowly developing neurodegenerative disorder associated with gradual decline in cerebration and laboriousness to perform routine piece of work. PD imposed a social burden on society through higher medical cost and by loss of social productivity in current era. The available treatment options are expensive and associated with serious adverse effect after long term use. Therefore, there is a critical clinical need to develop alternative pharmacotherapies from natural sources to prevent and cure the pathological hall marks of PD with minimal cost. Our study aimed to scrutinize the antiparkinsonian potential of curcuminoids-rich extract and its binary and ternary inclusion complexes. In healthy rats, 1 mg/kg haloperidol daily intraperitoneally, for 3 weeks was used to provoke Parkinsonism like symptoms except control group. Curcuminoids rich extract, binary and ternary inclusion complexes formulations 15-30 mg/kg, L-dopa and carbidopa (100 + 25 mg/kg) were orally administered on each day for 3 weeks. Biochemical, histopathological and RT-qPCR analyses were conducted after neurobehavioral observations. Findings of current study indicated that all curcuminoids formulations markedly mitigated the behavioral abnormalities, recovered the level of antioxidant enzymes, acetylcholinesterase inhibitory activity and neurotransmitters. Histological analysis revealed that curcuminoids supplements stabilized the neuronal loss, pigmentation and Lewy bodies' formation. The mRNA expressions of neuro-inflammatory and specific PD pathological biomarkers were downregulated by treatment with curcuminoids formulations. Therefore, it is suggested that these curcuminoids rich extract, binary and ternary supplements should be considered as promising therapeutic agents in development of modern anti-Parkinson's disease medications.

Pharmacological Potential of the Standardized Methanolic Extract of Prunus armeniaca L. in the Haloperidol-Induced Parkinsonism Rat Model

Parkinson's disease (PD) is a complex, age-related neurodegenerative disease that causes neuronal loss and dysfunction over time. An imbalance of redox potential of oxidative stress in the cell causes neurodegenerative diseases and dysfunction of neurons. Plants are a rich source of bioactive substances that attenuate oxidative stress in a variety of neurological disorders. The aim of the present study was to evaluate the Prunus armeniaca L. methanolic extract (PAME) for anti-Parkinson activity in rats. PD was induced with haloperidol (1 mg/kg, IP). The PAME was administered orally at 100, 300, and 800 mg/kg dose levels for 21 days. Behavioral studies (catalepsy test, hang test, open-field test, narrow beam walk, and hole-board test), oxidative stress biomarkers (SOD, CAT, GSH, and MDA) levels, neurotransmitters (dopamine, serotonin, and noradrenaline) levels, and acetylcholinesterase activity were quantified in the brain homogenate. Liver function tests (LFTs), renal function tests (RFTs), complete blood count (CBC), and lipid profiles were measured in the blood/serum samples to note the side effects of PAME at the selected doses. Histopathological analysis was performed on the brain (anti-PD study), liver, heart, and kidney (to check the toxicity of PAME on these vital organs). Motor functions were improved in the behavioral studies. Dopamine, serotonin, and noradrenaline levels were significantly increased (P < 0.001), whereas the level of acetylcholinesterase was decreased significantly (P < 0.001). The levels of superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH) were increased, while malondialdehyde (MDA) and nitrite levels were decreased in the PAME-treated groups significantly compared with the disease control group, hence reducing oxidative stress. The incidence of toxicity was determined by biochemical analysis of LFT and RFT biomarkers testing. The histopathological analysis indicated that neurofibrillary tangles and plaques decreased in a dose-dependent manner in the PAME-treated groups. Based on the data, it is concluded that PAME possessed good anti-Parkinson activity, rationalizing the plant's traditional use as a neuroprotective agent.

Therapeutic roles of plants for 15 hypothesised causal bases of Alzheimer's disease

Alzheimer's disease (AD) is progressive and ultimately fatal, with current drugs failing to reverse and cure it. This study aimed to find plant species which may provide therapeutic bioactivities targeted to causal agents proposed to be driving AD. A novel toolkit methodology was employed, whereby clinical symptoms were translated into categories recognized in ethnomedicine. These categories were applied to find plant species with therapeutic effects, mined from ethnomedical surveys. Survey locations were mapped to assess how this data is at risk. Bioactivities were found of therapeutic relevance to 15 hypothesised causal bases for AD. 107 species with an ethnological report of memory improvement demonstrated therapeutic activity for all these 15 causal bases. The majority of the surveys were found to reside within biodiversity hotspots (centres of high biodiversity under threat), with loss of traditional knowledge the most common threat. Our findings suggest that the documented plants provide a large resource of AD therapeutic potential. In demonstrating bioactivities targeted to these causal bases, such plants may have the capacity to reduce or reverse AD, with promise as drug leads to target multiple AD hallmarks. However, there is a need to preserve ethnomedical knowledge, and the habitats on which this knowledge depends.

A Comprehensive Insight into the Phytochemical, Pharmacological Potential, and Traditional Medicinal Uses of Albizia lebbeck (L.) Benth

Background. Albizialebbeck is a deciduous tree having tremendous medicinal utilities, for example, respiratory, skin, gastrointestinal, oral disorders, eye, urinary, genital, anorectal, inflammatory, and neurological disorders, and venereal diseases. Several studies have been undertaken on the medicinal and traditional values of A. lebbeck. Objective. The detailed information about its medicinal uses and pharmacological implications is highly scattered and distributed in different data sources. Hence, the study was conducted to supply an inclusive review of its ethnomedicinal uses, phytochemicals, and the available pharmacological attributes supporting its efficiency in traditional medicine. Method. Literature surveys were conducted on this medicinal plant via search engines like Google Scholar, PubMed, and Science Direct, and obtained information up to December 2020 has been assessed and analyzed for this study. Results. Systematic investigation revealed that A. lebbeck consists of various phytochemicals, including major alkaloids, flavonoids, saponins, and terpenoids. Its crude extract, fraction, and bioactive compounds exhibited potent adulticidal, antiallergic, anticancer, anticonvulsant, antidiabetic, antidiarrheal, anti-inflammatory, antimicrobial, antinociceptive, antioxidant, antiparasitic, antipyretic, antivenom, estrogenic, neuroprotective, nootropic, ovicidal, and wound healing activities. Conclusions. This study proposes that A. lebbeck remains a rich source of phytochemicals with various biological activities which possess outstanding therapeutic benefits to humanity across the world. However, studies are required to estimate the potential side effects. Moreover, mechanistic physiognomies of the isolated compounds with known bioactivities are quite limited; thus, forthcoming research needs to focus on the mechanisms of these active phytochemicals to facilitate their potential enrolling for drug discovery.

Ameliorative effect of ethoxylated chalcone-based MAO-B inhibitor on behavioural predictors of haloperidol-induced Parkinsonism in mice: evidence of its antioxidative role against Parkinson's diseases

Parkinson's disease is a progressive neurodegenerative disorder that affects mostly elderly people above the age of 60. Previously, we have reported that the ethoxylated chalcone derivative (E)-1-(4-ethoxyphenyl)-3-(fluorophenyl)prop-2-en-1-one (E7) showed potent, reversible, and competitive MAO-B inhibition with an IC₅₀ value of 0.053 μm. The present study aims to investigate the anti-Parkinson activity of compound E7 in a haloperidol-induced animal model of mice. The disease was induced with haloperidol (1 mg/kg, intraperitoneal route) once daily for 21 days. E7 was given at dose levels of 10, 20, and 30 mg/kg/day for 21 days, consecutively. Behavioural tests were carried out during and at the end of the study. Biochemical analyses such as oxidative stress biomarkers and neurotransmitters were quantified on the brain homogenate at the end of the study. Behavioural results showed that there is a marked improvement in locomotor activity and motor coordination in the treatment group. Oxidative stress biomarkers such as SOD, CAT, and GSH levels were increased dose-dependently with a maximum at 30 mg/kg, whereas the dose-dependent decrease (30 mg/kg) in the MDA and nitrite levels were observed in the treatment groups. Levels of neurotransmitters, such as dopamine, serotonin, and noradrenaline, were increased in the treatment groups while dopamine and noradrenaline levels were more than in the standard treated group. MAO-B level was also decreased dose dependently in the treatment group in comparison with the control group. Based on the findings, it was concluded that the E7 compound exhibited anti-Parkinson activity which was more evident at 30 mg/kg oral dose as evaluated by the haloperidol-induced animal model of mice.

Neuroprotective potential of Malva neglecta is mediated via down-regulation of cholinesterase and modulation of oxidative stress markers

Alzheimer's disease affects daily routine due to loss of memory and decline in cognition. In vitro data showed acetylcholine esterase inhibition activity of Malva neglecta but no in vivo evidence is available. The current study aims to investigate the anti-Alzheimer's activity of Malva neglecta methanolic extract in the AlCl₃-induced Alzheimer disease rats' model. Thirty Wistar rats were divided into six groups and respective doses were given orally for 21 days. Behavioural observations were recorded and biochemical analysis was performed on brain homogenate. Improvement in memory and cognition was noted in treated rats as compared to disease control. A dose-dependent decrease (0.530 ± 0.009 at 200 mg/kg, 0.212 ± 0.007 at 400 mg/kg, 0.173 ± 0.005 at 600 mg/kg) in AChE activity was noted in the treatment groups with reference to disease control value (1.572 ± 0.013). This decrease in AChE activity is linked with an increase in acetylcholine in the brain which plays a key role in retaining memory. Oxidative stress biomarkers; GSH (66.77 ± 0.01 at 600 mg/kg), SOD (26.60 ± 0.10 at 600 mg/kg), CAT (21.46 ± 0.01 at 600 mg/kg) levels were increased with a decrease in MDA (103.33 ±0.49 at 600 mg/kg) level in a dose-dependently manner in the treatment groups as compared to disease control respective values. It is concluded that Malva neglecta could ameliorate Alzheimer's symptoms possibly by decreasing AChE activity and oxidative stress.

Toxicity Evaluation of the Naphthalen-2-yl 3,5-Dinitrobenzoate: A Drug Candidate for Alzheimer Disease

The presented study was designed to probe the toxicity potential of newly identified compound naphthalen-2-yl 3,5-dinitrobenzoate (SF1). Acute, subacute toxicity and teratogenicity studies were performed as per Organization of economic cooperation and development (OECD) 425, 407, and 414 test guidelines, respectively. An oral dose of 2000 mg/kg to rats for acute toxicity. Furthermore, 5, 10, 20, and 40 mg/kg doses were administered once daily for 28 days in subacute toxicity study. Teratogenicity study was performed with 40 mg/kg due to its excellent anti-Alzheimer results at this dose. SF1 induced a significant rise in Alkaline Phosphatases (ALP), bilirubin, white blood cells (WBC), and lymphocyte levels with a decrease in platelet count. Furthermore, the reduction in urea, uric acid, and aspartate transaminase (AST) levels and an increase in total protein levels were measured in subacute toxicity. SF1 increased spermatogenesis at 5 and 10 mg/kg doses. Teratogenicity study depicted no resorptions, early abortions, cleft palate, spina bifida and any skeletal abnormalities in the fetuses. Oxidative stress markers (Superoxide dismutase (SOD), Catalase (CAT), and glutathione (GSH) were increased in all the experiments, whereas the effect on melanoaldehyde Malondialdehyde (MDA) levels was variable. Histopathology further corroborated these results with no change in the architectures of selected organs. Consequently, a 2000 mg/kg dose of SF1 tends to induce minor liver dysfunction along with immunomodulation, and it is well below its LD ₅₀ . Moreover, it can be safely used in pregnancy owing to its no detectable teratogenicity.

Quercetin-Conjugated Superparamagnetic Iron Oxide Nanoparticles Protect AlCl3-Induced Neurotoxicity in a Rat Model of Alzheimer's Disease via Antioxidant Genes, APP Gene, and miRNA-101

Alzheimer's disease (AD) is a neurodegenerative disease with cognitive impairment. Oxidative stress in neurons is considered as a reason for development of AD. Antioxidant agents such as quercetin slow down AD progression, but the usage of this flavonoid has limitations because of its low bioavailability. We hypothesized that quercetin-conjugated superparamagnetic iron oxide nanoparticles (QT-SPIONs) have a better neuroprotective effect on AD than free quercetin and regulates the antioxidant, apoptotic, and APP gene, and miRNA-101. In this study, male Wistar rats were subjected to AlCl3, AlCl3 + QT, AlCl3 + SPION, and AlCl3 + QT-SPION for 42 consecutive days. Behavioral tests and qPCR were used to evaluate the efficiency of treatments. Results of behavioral tests revealed that the intensity of cognitive impairment was decelerated at both the middle and end of the treatment period. The effect of QT-SPIONs on learning and memory deficits were closely similar to the control group. The increase in expression levels of APP gene and the decrease in mir101 led to the development of AD symptoms in rats treated with AlCl3 while these results were reversed in the AlCl3 + QT-SPIONs group. This group showed similar results with the control group. QT-SPION also decreased the expression levels of antioxidant enzymes along with increases in expression levels of anti-apoptotic genes. Accordingly, the antioxidant effect of QT-SPION inhibited progression of cognitive impairment via sustaining the balance of antioxidant enzymes in the hippocampus of AD model rats.

Anti-Parkinson's Activity of Tribulus terrestris via Modulation of AChE, α-Synuclein, TNF-α, and IL-1β

Tribulus terrestris (T.T.) is a rich source of flavonoids and saponins, which have been reported to have neuroprotective and antioxidant potential. The current study was planned to investigate the anti-Parkinson's activity of T. terrestris methanol extract (TTME). It was hypothesized that TTME possessed antioxidant potential and can ameliorate Parkinson's disease (PD) via modulation of α-synuclein, acetylcholinesterase (AChE), TNF-α, and IL-1β. To test this hypothesis, in silico and in vivo studies were performed. The PD model in rats was prepared by giving haloperidol, 1 mg/kg, i.p. Rats were divided into six groups: control, disease control, standard, and treatment groups receiving TTME orally at 100, 300, and 1000 mg/kg dose levels for 21 days. Behavioral observations and biochemical analyses were done. The TTME modulatory effect on mRNA expression of α-synuclein, AChE, TNF-α, and interleukins in the brain homogenate was estimated by RT-PCR. Compounds detected in HPLC analysis disrupted the catalytic triad of AChE in in silico studies. Behavioral observations showed significant (p < 0.05) improvement in a reversal of catatonia, muscular strength, locomotor functions, stride length, and exploration in a dose-dependent manner (1000 >300 >100 mg/kg) of PD rats. Endogenous antioxidant enzyme levels CAT, SOD, GSH, and GPx were significantly restored at a high dose (p < 0.05) with a notable (p < 0.05) decrease in the MDA level in TTME-treated groups. TTME at a high dose significantly (p < 0.05) decreased the level of acetylcholinesterase. RT-PCR results are showing down-regulation in the mRNA expression levels of IL-1β, α -synuclein, TNF-α, and AChE in TTME-treated groups compared to the disease control group, indicating neuroprotection. It is concluded that TTME has potential to ameliorate the symptoms of Parkinson's disease.

Exploring the Therapeutic Potentials of Highly Selective Oxygenated Chalcone Based MAO-B Inhibitors in a Haloperidol-Induced Murine Model of Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder of dopaminergic, noradrenergic, and serotonergic systems, in which dopamine, noradrenaline, and serotonin levels are depleted and lead to the development of motor and non-motor symptoms such as tremor, bradykinesia, weight changes, fatigue, depression, and visual hallucinations. Therapeutic strategies place much focus on dopamine replacement and the inhibition of dopamine metabolism. The present study was based on the known abilities of chalcones to act as molecular scaffolds that selectively inhibit MAO-B with the added advantage of binding reversibly. Recently, we synthesized a series of 26 chalcone compounds, amongst which (2E)-1-(2H-1,3-benzodioxol-5-yl)-3-(4-fluorophenyl)prop-2-en-1-one (O10) and (2E)-1-(2,3-dihydro-1,4-benzodioxin-6-yl)-3-(4-fluorophenyl)prop-2-en-1-one (O23) most inhibited MAO-B. Hence, the present study was performed to explore the molecular mechanisms responsible for the neuroprotective effect of O10 and O23 at varying doses such as 10, 20, and 30 mg/kg each in a haloperidol-induced murine model of PD. Both compounds were effective (though O23 was the more effective) at ameliorating extrapyramidal and non-motor symptoms in the model and improved locomotory and exploratory behaviors, reduced oxidative stress markers, and enhanced antioxidant marker and neurotransmitter levels. Furthermore, histopathological studies showed O10 and O23 both reduced neurofibrillary tangles and plaques to almost normal control levels.

β-Carotene: A Natural Compound Improves Cognitive Impairment and Oxidative Stress in a Mouse Model of Streptozotocin-Induced Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease characterized by a cascade of changes in cognitive, behavioral, and social activities. Several areas of the brain are involved in the regulation of memory. Of most importance are the amygdala and hippocampus. Antioxidant therapy is used for the palliative treatment of different degenerative diseases like diabetes, cirrhosis, and Parkinson's, etc. The objective of this study was to assess the effectiveness of exogenous antioxidants, in particular, β carotene (1.02 and 2.05 mg/kg) against intracerebroventricular injected streptozotocin-induced memory impairment in mice. Streptozotocin (3 mg/kg, i.c.v) was administered in two separate doses (on 1st and 3rd days of treatment) for neurodegeneration. Fifty Albino mice (male) were selected in the protocol, and they were classified into five groups (Group I-control, Group II-disease, Group III-standard, Group IV-V-β-carotene-treated) to investigate the cognitive enhancement effect of selected antioxidants. The cognitive performance was observed following the elevated plus-maze, passive avoidance, and open field paradigms. Acetylcholine esterase, β-amyloid protein, and biochemical markers of oxidative stress such as glutathione peroxidase, superoxide dismutase, and catalase were analyzed in brain homogenates. In silico activity against acetylcholinesterase (AChE) was determined by the molecular modeling of β-carotene. β-carotene at a dose of 2.05 mg/kg was found to attenuate the deleterious effects of streptozotocin-induced behavioral and biochemical impairments, including the inhibition of acetylcholinesterase activity. The in silico studies confirmed the binding capacity of β-carotene with the acetylcholinesterase enzyme. The administration of β-carotene attenuated streptozotocin-induced cognitive deficit via its anti-oxidative effects, inhibition of acetylcholinesterase, and the reduction of amyloid β-protein fragments. These results suggest that β-carotene could be useful for the treatment of neurodegenerative diseases such as Alzheimer's disease.