Ethanolic Extract of Orthosiphon stamineus Improves Memory in Scopolamine-Induced Amnesia Model

Rhoifolin, baicalein 5,6-dimethyl ether and agathisflavone prevent amnesia induced in scopolamine zebrafish (Danio rerio) model by increasing the mRNA expression of bdnf, npy, egr-1, nfr2α, and creb1 genes

The increasing attention towards age-related diseases has generated significant interest in the concept of cognitive dysfunction associated with Alzheimer's disease (AD). Certain limitations are associated with the current therapies, and flavonoids have been reported to exhibit multiple biological activities and anti-AD effects in several AD models owing to their antioxidative, anti-inflammatory, and anti-amyloidogenic properties. In this study, we performed an initial in silico predictions of the pharmacokinetic properties of three flavonoids (rhoifolin, baicalein 5,6-dimethyl ether and agathisflavone). Subsequently, we evaluated the antiamnesic and antioxidant potential of flavonoids in concentrations of 1, 3, and 5 μg/L in scopolamine (100 μM)-induced amnesic zebrafish (Danio rerio) model. Zebrafish behavior was analyzed by novel tank diving test (NTT), Y-maze, and novel object recognition test (NOR). Acetylcholinesterase (AChE) activity, brain antioxidant status and the expression of bdnf, npy, egr1, nrf2α, creb1 genes, and CREB-1 protein level was measured to elucidate the underlying mechanism of action. Our flavonoids improved memory and decreased anxiety-like behavior of scopolamine-induced amnesia in zebrafish. Also, the studied flavonoids reduced AChE activity and brain oxidative stress and upregulated the gene expression, collectively contributing to neuroprotective properties. The results of our study add new perspectives on the properties of flavonoids to regulate the evolution of neurodegenerative diseases, especially AD, by modulating the expression of genes involved in the regulation of synaptic plasticity, axonal growth, and guidance, sympathetic and vagal transmission, the antioxidant response and cell proliferation and growth.

Melittin - the main component of bee venom: a promising therapeutic agent for neuroprotection through keap1/Nrf2/HO-1 pathway activation

The Nuclear factor erythroid 2-related factor (Nrf2)/ Heme oxygenase-1 (HO-1) pathway, known for its significant role in regulating innate antioxidant defense mechanisms, is increasingly being recognized for its potential in neuroprotection studies. Derived from bee venom, melittin's neuroprotective effects have raised interest. This study confirmed that melittin specificity upregulated the weakened Nrf2/HO-1 signaling in mice brain. Interestingly, we also revealed melittin's efficient tactic, as it was suggested to first restore redox balance and then gradually stabilized other regulations of the mouse hippocampus. Using a neuro-stress-induced scopolamine model, chromatography and mass spectrometry analysis revealed that melittin crossed the compromised blood-brain barrier and accumulated in the hippocampus, which provided the chance to interact directly to weakened neurons. A wide range of improvements of melittin action were observed from various tests from behavior Morris water maze, Y maze test to immune florescent staining, western blots. As we need to find out what is the focus of melittin action, we conducted a careful observation in mice which showed that: the first signs of changes, in the hippocampus, within 5 h after melittin administration were the restoration of the Nrf2/HO-1 system and suppression of oxidative stress. After this event, from 7 to 12.5 h after administration, a diversity of conditions was all ameliorated: inflammation, apoptosis, neurotrophic factors, cholinergic function, and tissue ATP level. This chain reaction underscores that melittin focus was on redox balance's role, which revived multiple neuronal functions. Evidence of enhancement in the mouse hippocampus led to further exploration with hippocampal cell line HT22 model. Immunofluorescence analysis showed melittin-induced Nrf2 translocation to the nucleus, which would initiating the translation of antioxidant genes like HO-1. Pathway inhibitors pinpointed melittin's direct influence on the Nrf2/HO-1 pathway. 3D docking models and pull-down assays suggested melittin's direct interaction with Keap1, the regulator of the Nrf2/HO-1 pathway. Overall, this study not only highlighted melittin specifically effect on Nrf2/HO-1, thus rebalancing cellular redox, and also showed that this is an effective multi-faceted therapeutic strategy against neurodegeneration.

Dihydroergotamine Increases Histamine Brain Levels and Improves Memory in a Scopolamine-Induced Amnesia Model

The beneficial effects of increasing histamine levels on memory have acquired special interest due to their applicability to psychiatric conditions that cause memory impairments. In addition, by employing drug repurposing approaches, it was demonstrated that dihydroergotamine (DHE), an FDA drug approved to treat migraines, inhibits Histamine N Methyl Transferase (HNMT), the enzyme responsible for the inactivation of histamine in the brain. For this reason, in the present work, the effect of DHE on histamine levels in the hippocampus and its effects on memory was evaluated, employing the scopolamine-induced amnesia model, the Novel Object Recognition (NOR) paradigm, and the Morris Water Maze (MWM). Furthermore, the role of histamine 1 receptor (H1R) and histamine 2 receptor (H2R) antagonists in the improvement in memory produced by DHE in the scopolamine-induced amnesia model was evaluated. Results showed that the rats that received DHE (10 mg/kg, i.p.) showed increased histamine levels in the hippocampus after 1 h of administration but not after 5 h. In behavioral assays, it was shown that DHE (1 mg/kg, i.p.) administered 20 min before the training reversed the memory impairment produced by the administration of scopolamine (2 mg/kg, i.p.) immediately after the training in the NOR paradigm and MWM. Additionally, the effects in memory produced by DHE were blocked by pre-treatment with pyrilamine (20 mg/kg, i.p.) administered 30 min before the training in the NOR paradigm and MWM. These findings allow us to demonstrate that DHE improves memory in a scopolamine-induced amnesia model through increasing histamine levels at the hippocampus due to its activity as an HNMT inhibitor.

Orthosiphon aristatus (Blume) Miq. Extracts attenuate Alzheimer-like pathology through anti-inflammatory, anti-oxidative, and β-amyloid inhibitory activities

ETHNOPHARMACOLOGICAL RELEVANCE

Orthosiphon aristatus (Blume) Miq. (OA) is a traditional folk-herb, which is usually used to treat acute and chronic nephritis, epilepsy, cystitis, and other diseases. Phenols and flavonoids are the main active compound compounds of OA, with proven anti-inflammatory and antioxidant activities.

AIMS OF THIS STUDY

Based on evidenced therapeutic activities, we aimed to investigate the impact of OA on Alzheimer's disease (AD) which is the most common age-related neurodegenerative disease, and the pathological features include accumulation of beta-amyloid (Aβ) and neurofibrillary tangles (NFT).

MATERIALS AND METHODS

OA was extracted with water, methanol, chloroform, and ethyl acetate, and determined its total flavonoid and phenolic contents. Initially, Aβ1-42 based cytotoxicity was induced in BV2 cells and C6 cells to investigate the therapeutic impact of OA therapy by MTT, RT-PCR, Western blot, and ELISA. Further, Aβ1-42 Oligomer (400 pmol)-induced AD mice model was established to evaluate the impact of OA extract on improving learning and memory impairment.

RESULTS

The results showed that the extract of OA could increase cell survival, inhibit the expression of TNF-α, IL-6, IL-1β, COX-2, and iNOS, and increase BDNF levels. We infer that the OA extract may attenuate Aβ-induced cytotoxicity by retarding the production of inflammatory-related factors. In the animal behavior test, the number of mice entering darkroom and the time of arriving at the platform were significantly reduced, indicating the learning and memory-improving ability of OA extract.

CONCLUSIONS

These findings imply that the OA ethanolic extract demonstrated an improving effect on memory and hence could serve as a potential therapeutic target for the treatment of neurodegenerative diseases like AD.

The ameliorative effect of Piper trioicum in attenuating cognitive deficit in scopolamine induced neurotoxicity in experimental rats

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional system of medicine, Piper species, or its components are widely used to treat many diseases including memory improvement. One of the wild species Piper trioicum Roxb. (Piperaceae) is found in South Asian countries. The whole plant is used as folk medicine to improve memory.

AIM OF THE STUDY

To our knowledge, no previous research has investigated the neuroprotective activities of P. trioicum. So, we studied the ameliorative effect of P. trioicum in attenuating cognitive deficit in scopolamine induced neurotoxicity in experimental rats.

MATERIALS AND METHODS

Wistar rats were exposed to scopolamine (3 mg/kg, i. p.) for 14 consecutive days, and the effect of P. trioicum (HAPT; oral, 300, 400 mg/kg) on scopolamine-invoked neurotoxicity in brain were studied. During the experimental period, behaviour analyses of rats were observed 30 min post-drug administration. The role of antioxidants of HAPT in scavenging cellular oxygen/peroxyl radicals were studied. Acetylcholinesterase and butyrylcholinesterase inhibitions, and mode of inhibition kinetics of HAPT were studied. Pathogenic cellular oxidative (MDA, GSH, SOD, and CAT), DNA damage (8-oxodG), neurochemical (acetyl- and, butyryl-cholinesterase), β-secretase (BACE-1 and 2), MAPτ, and neuroinflammation (IL-6, TNF-α) biomarkers in extension to the histopathological observation of brain cortex were studied. GC-MS/MS analysis was carried out to investigate the presence of bioactive constituents in HAPT.

RESULTS

HAPT, a rich source of phenol and flavonoid type antioxidants were responsible in quenching oxygen/peroxyl radicals and protected the cellular membrane, and lipoproteins against ROS in DPPH, ORAC, and CAPe tests. HAPT inhibited acetylcholinesterase and butyrylcholinesterase activities, and showed competitive-inhibition (reversible) towards cholinesterase activities. HAPT-400 significantly improved the learning and memory-impairment by restoring oxidative MDA, GSH, SOD, CAT, and DNA damage (8-oxodG) markers of serum, and cortex. It also improved acetyl- and, butyryl-cholinesterase, β-secretase, and MAPτ level in brain by restoring proinflammatory cytokines IL-6, and TNF-α indicators in neurotoxic rats. GC-MS/MS reported therapeutic significance active compounds were molecular-docked towards target proteins, found that proscillaridin showed the highest affinity towards AChE, BuChE, BACE1, and BACE2 with binding energy of ΔGb -9.1, ΔGb -10.2, ΔGb -11.4 and ΔGb -11.5 Kcal/mol, respectively. Cymarin and morphine-3-glucuronide showed the second highest binding affinity towards AChE (ΔGb -8.8) and BuChE (ΔGb -10.0), respectively. In BACE-1, betulin showed the second highest binding affinity ΔGb -10.7 Kcal/mol and in BACE-2, morphine-3-glucuronide showed the second highest binding affinity ΔGb -9.8 Kcal/mol.

CONCLUSIONS

Synergistic impact of proscillaridin, Cymarin, morphine-3-glucuronide, betulin like compounds in HAPT improved memory impairment, healing of tissue architecture of cortex with the restoration of neurochemical, neuroinflammation, and oxidative indicators in neurotoxic rats.

Piceatannol improved cerebral blood flow and attenuated JNK3 and mitochondrial apoptotic pathway in a global ischemic model to produce neuroprotection

Cerebral ischemia is one of the leading causes of death and disability worldwide. The only FDA-approved treatment is recanalization with systemic tissue plasminogen activators like alteplase, although reperfusion caused by recanalization can result in neuroinflammation, which can cause brain cell apoptosis. Therefore, after an ischemic/reperfusion injury, interventions are needed to minimize the neuroinflammatory cascade. In the present study, piceatannol (PCT) was studied for its neuroprotective efficacy in a rat model of global ischemic injury by attenuating c-Jun N-terminal kinase 3 (JNK3) downstream signaling. PCT is a resveratrol analog and a polyphenolic stilbenoid naturally occurring in passion fruit and grapes. The neuroprotective efficacy of PCT (1, 5, 10 mg/kg) in ischemic conditions was assessed through pre- and post-treatment. Cerebral blood flow (CBF) and tests for functional recovery were assessed. Protein and gene expression were done for JNK3 and other inflammatory markers. A docking study was performed to identify the amino acid interaction. The results showed that PCT improved motor and memory function as measured by a functional recovery test believed to be due to an increase in cerebral blood flow. Also, the caspase signaling which promotes apoptosis was found to be down-regulated; however, nitric oxide synthase expression was up-regulated, which could explain the enhanced cerebral blood flow (CBF). According to our findings, PCT impeded c-Jun N-terminal kinase 3 (JNK3) signaling by suppressing phosphorylation and disrupting the mitochondrial apoptotic pathway, which resulted in the neuroprotective effect. Molecular docking analysis was performed to investigate the atomic-level interaction of JNK3 and PCT, which reveals that Met149, Leu206, and Lys93 amino acid residues are critical for the interaction of PCT and JNK3. According to our current research, JNK3 downstream signaling and the mitochondrial apoptosis pathway are both inhibited by PCT, which results in neuroprotection under conditions of global brain ischemia. Piceatannol attenuated JNK3 phosphorylation during the ischemic condition and prevented neuronal apoptosis.

Barbigerone prevents scopolamine-induced memory impairment in rats by inhibiting oxidative stress and acetylcholinesterase levels

The current study was designed for the evaluation of barbigerone on memory loss. In this experimental study, 24 Wistar rats (n = 6) were used. Control rats and scopolamine (SCOP)-treated control group rats were orally administered with 3 ml of 0.5% sodium carboxymethyl cellulose (vehicle), whereas barbigerone was (10 and 20 mg kg-1) administered orally to the rats from the test group. During the 14-day treatment, control group rats were given 3 ml kg-1 day-1 saline, and all other groups were administered SCOP (1 mg kg-1 day-1, i.p.) 1 h after barbigerone p.o. treatment. The spontaneous alternation activities, learning capacities of a rat's memory were tested with Morris water maze and Y-maze. Reduced glutathione, malondialdehyde, acetylcholine esterase (AChE) and catalase (CAT) levels were measured in rat brain tissue as oxidative stress/antioxidant markers. Moreover, the levels of tumour necrosis factor, interleukin-6 (IL-6) and IL-1β were also estimated. Treatment with barbigerone in SCOP-administered rats dramatically reduced SCOP-induced neurobehavioural deficits, oxidative stress and neuroinflammatory markers, improved endogenous antioxidants, and restored AChE activity. By improving cholinergic function and reducing oxidative damage, barbigerone could mitigate the effects of SCOP-induced changes in the brain.

Neuroprotective role of medicinal plant extracts evaluated in a scopolamine-induced rat model of Alzheimer's disease

BackgroundAlzheimer's disease is a debilitating neurological brain disease with memory impairment among the first signs. Scopolamine (SCO), a muscarinic receptor antagonist that disrupts cognition and memory acquisition, is considered a psychopharmacological AD model. We investigate the effectiveness of medicinal plants in mitigating the SCO-induced neurobehavioural damage in rats.Materials and MethodsAnimals were injected with Scopolamine hydrobromide trihydrate (2.2 mg/kg IP.) daily for 2 months. Each treatment group was administered one of four medicinal spice extracts (Nigella sativa, 400 mg/kg; rosemary, 200 mg/kg; sage, 600 mg/kg and ginseng;200 mg/kg 90 minutes after SCO injection. Animals were subjected to cognitive-behavioral tests (NOR, Y-maze, and MWM). After the experiment, we extracted the brains for histopathological examination and biochemical assessment for oxidative stress (levels of TT, CAT and TBARS) and gene expression of acetylcholinesterase and brain monoamines.ResultsAs expected, SCO treatment impaired memory and cognition, increased oxidative stress, decreased neurotransmitters, and caused severe neurodegenerative changes in the brain.ConclusionSurprisingly, these effects were measurably moderated by the administration of all four plant extracts, indicating a neuroprotective action that we suggest could alleviate AD disease manifestations.

Chemical characterization and evaluation of the neuroprotective potential of Indigofera sessiliflora through in-silico studies and behavioral tests in scopolamine-induced memory compromised rats

In the current study, we investigated the phytochemical and neuropharmacological potential of Indigofera sessiliflora, an indigenous least characterized plant widely distributed in deserted areas of Pakistan. The crude extract of the whole plant Indigofera sessiliflora (IS.CR) was preliminary tested in-vitro for the existence of polyphenol content, antioxidant and anticholinesterase potential followed by detailed chemical characterization through UHPLC-MS. Rats administered with different doses of IS.CR (100-300 mg/kg) for the duration of 4-weeks were behaviorally tested for anxiety and cognition followed by biochemical evaluation of dissected brain. The in-silico studies were employed to predict the blood-brain barrier crossing tendencies of secondary metabolites with the elucidation of the target binding site. The in-vitro assays revealed ample phenols and flavonoids content in IS.CR with adequate anti-oxidant and anticholinesterase potential. The dose-dependent anxiolytic potential of IS.CR was demonstrated in open field (OFT), light/dark (L/D) and elevated plus maze (EPM) tests as animals spent more time in open, illuminated and elevated zones (P < 0.05). In the behavioral tests for learning/memory, the IS.CR reversed the scopolamine-induced cognitive deficits, as animals showed better (P < 0.05) spontaneous alternation and discrimination index in y-maze and novel object recognition (NOR) tests. Similarly, as compared to amnesic rats, the step-through latencies were increased (P < 0.05) and escape latencies were decreased (P < 0.05) in passive avoidance (PAT) and Morris water maze (MWM) tests, respectively. Biochemical analysis of rat brains showed significant reduction in malondialdehyde and acetylcholinesterase levels, alongwith preservation of glutathione peroxidase and superoxide dismutase activity. The docking studies further portrayed a possible interaction of detected phytoconstituents with acetylcholinesterase target. The results of the study show valuable therapeutic potential of phytoconstituents present in IS.CR to correct the neurological disarrays which might be through antioxidant activity or via modulation of GABAergic and cholinergic systems by artocommunol, 1,9-dideoxyforskolin and 6E,9E-octadecadienoic acid.

Sulforaphane enhances long-term potentiation and ameliorate scopolamine-induced memory impairment

Increases in human life expectancy have led to increases in the prevalence of senile dementia and neurodegenerative diseases. This is a major problem because there are no curative treatments for these diseases, and patients with unmanaged cognitive and neurodegenerative symptoms experience many social problems. Sulforaphane is a type of organosulfur compound known as an isothiocyanate. It is derived from glucoraphanin, a compound found in cruciferous vegetables such as broccoli, brussels sprouts, and cabbages, via an enzymatic reaction that is triggered by plant damage (e.g., chewing). Sulforaphane exhibits activity against cancer, inflammation, depression, and severe cardiac diseases. It can also alleviate oxidative stress and neural dysfunction in the brain. However, there is insufficient knowledge about the electrophysiological and behavioral basis of the effects of sulforaphane on learning and memory. Therefore, we evaluated whether acute sulforaphane administration affected long-term potentiation (LTP) in organotypic cultured rat hippocampal tissues. We also measured the effect of sulforaphane on the performance of three behavioral tests, the Y-maze test, the passive avoidance test, and the Morris water maze, which assess short-term memory, avoidance memory, and short and long-term spatial memory, respectively. We found that sulforaphane increased the total field excitatory postsynaptic potential (fEPSP) in a dose-dependent manner after high frequency stimulation and attenuated scopolamine-induced interference of the fEPSP in the hippocampal CA1 area. Sulforaphane also restored cognitive function and inhibited memory impairment as indicated by the alleviation of the negative neurological effects of scopolamine, i.e, a lowered ratio of spontaneous alternation in the Y-maze, a reduced step-through latency in the passive avoidance test, and an increased navigation time in the Morris water maze. These results indicate that sulforaphane can effectively prevent the attenuation of LTP and cognitive abilities induced by cholinergic and muscarinic receptor blockade. Further research is warranted to explore the potential therapeutic and prophylactic utility of sulforaphane for improving learning and memory, especially in those suffering from neurodegenerative disorders.

A Systematic Review of the Protective Actions of Cat's Whiskers (Misai Kucing) on the Central Nervous System

Orthosiphon stamineus (OS) or Orthosiphon aristatus var. aristatus (OAA) is commonly known as cat's whiskers or "misai kucing". It is an herbaceous shrub that is popular in many different traditional and complementary medicinal systems. Its popularity has been justified by the plethora of studies that have shown that the secondary metabolites of the plant has effects that range from anti-inflammatory and gastroprotective to anorexic and antihypertensive. As such, OS could also be a potential treatment for Central Nervous System (CNS) disorders. However, a cohesive synthesis of the protective actions of OS was lacking. This systematic review was therefore commenced to elaborate on the various protective mechanisms of OS in the CNS. The PRISMA model was used and five databases (Google Scholar, SCOPUS, SpringerLink, ScienceDirect, and PubMed) were searched with relevant keywords to finally identify four articles that met the inclusion criteria. The articles described the protective effects of OS extracts on Alzheimer's disease, epilepsy, learning and memory, oxidative stress, and neurotoxicity. All the articles found were experimental or preclinical studies on animal models or in vitro systems. The reported activities demonstrated that OS could be a potential neuroprotective agent and might improve CNS conditions like neurodegeneration, neuroinflammation, and oxidative stress.

Orthosiphon stamineus Standardized Extract Reverses Streptozotocin-induced Alzheimer's Disease-Like Condition in a Rat Model

Alzheimer’s disease (AD) is a chronic neurodegenerative brain disease that is characterized by impairment in cognitive functioning as well as the presence of intraneuronal neurofibrillary tangles (NFTs) and extracellular senile plaques. There is a growing interest in the potential of phytochemicals to improve memory, learning, and general cognitive abilities. The Malaysian herb Orthosiphon stamineus is a traditional remedy that possesses anti-inflammatory, anti-oxidant, and free-radical scavenging abilities, all of which are known to protect against AD. Previous studies have reported that intracerebroventricular (ICV) administration of streptozotocin (STZ) mimics a condition similar to that observed in AD. This experiment thus aimed to explore if an ethanolic leaf extract of O. stamineus has the potential to be a novel treatment for AD in a rat model and can reverse the STZ- induced learning and memory dysfunction. The results of this study indicate that O. stamineus has the potential to be potentially effective against AD-like condition, as both behavioral models employed in this study was observed to be able to reverse memory impairment. Treatment with the extract was able to decrease the up-regulated expression levels of amyloid precursor protein (APP), microtubule associated protein tau (MAPT), Nuclear factor kappa-light-chain-enhancer of activated B cells (NFᴋB), glycogen synthase kinase 3 alpha (GSK3α), and glycogen synthase kinase 3 beta (GSK3β) genes indicating the extract’s neuroprotective ability. These research findings suggest that the O. stamineus ethanolic extract demonstrated an improved effect on memory, and hence, could serve as a potential therapeutic target for the treatment of neurodegenerative diseases such as AD.