Neurodegenerative disorders

Neurodegenerative diseases are those that mainly affect neurons in the human brain and spinal cord. These diseases are sporadic and hereditary, and are normally debilitating and incurable. This is because once the neurons have been damaged or died, they are irreplaceable by the body because neurons do not reproduce. The fact that neurodegenerative diseases are incurable causes ataxia, which is the problem with movement, and dementia, which is mental dysfunction. Most of body’s activities such as movement, talking, maintaining balance, heart function and breathing are affected. Although these diseases have no cure, treatment is of the essence in order to relieve pain, ease symptoms and increase mobility.

Neurodegenerative brain diseases affect various parts of the brain such as cerebellum, brain stem, intracranial white matter, hypothalamus, thalamus, basal ganglia, and cerebral cortex. The diseases normally cause atrophy of the affected peripheral or central structures of the nervous system. Examples of neurodegenerative diseases include Huntington’s disease, Encephalitis, Brain Cancer, Stroke, Head and Brain malformations, Amyotrophic Lateral Sclerosis (Lou Gehrig’s disease or ALS), Parkinson’s disease, Hydrocephalus, Multiple Sclerosis, Genetic Brain Disorders, Prion Diseases, Alzheimer’s disease, Epilepsy, Degenerative Nerve Diseases, and other dementias. Dementias are the most widespread form of the disease, followed by Alzheimer’s disease, which accounts for 60-70% of the cases.

There are a number of risk factors associated with neurodegenerative diseases, with aging being the greatest factor. Oxidative stress and mitochondrial DNA mutations mainly contribute to aging. Other risk factors and causatives include viruses, toxins, alcoholism, chemicals, a tumor or any form of stroke. However, most of neurodegenerative diseases are caused by genetic mutations and neurodegeneration. This involves loss of function and structure or death of the neurons in a progressive manner.

Alzheimer’s disease (AD) is a popular form of dementia. Dementia is a mental disorder characterized by memory loss and interruption of intellectual abilities and social skills that could affect one’s daily life. The disease affects the part of the brain that controls language, memory and thought. The onset of the disease is slow, but the symptoms get worse with time. The early symptoms of Alzheimer’s disease are mild, but one may not respond to the environment or engage in a conversation in the later stages of the disease. However, the progression of the disease varies form one individual to another. The disease develops when the connections between the brain cells degenerate and die. Consequently, this leads to a steady decline in mental function and memory. The two prime factors crucial in the development of AD are age and any condition lowering cerebral perfusion, for instance, vascular-risk factor.

People who develop this disease have difficulty reading, writing and speaking. They may also not recognize family members, names of people they are familiar with or even recent events. At times, they may forget to essential personal care habits like brushing their teeth or combing their hair. They also experience a change in behavior where they become aggressive and express anxiety, with a tendency to wander away from home. Majority of the people who develop this disease are above 65 years of age, but some cases have been reported among people between 40 and 50 years old.

Alzheimer’s disease is reported to be the sixth major cause of demise in the United States of America. The survival range of patients living with the disease varies from four to twenty years, which are dependent on one’s health conditions and age. However, once the symptoms have become noticeable, one may live for approximately eight years. Currently, there is no available cure for Alzheimer’s disease, but there is effective treatment available to stop the progression of the disease. These treatments slow down the progression of dementia symptoms and aid in making the life of the patients better than before.

The central nervous system (CNS) is protected from inflammation by the blood-brain barrier. However, the CNS has the ability to induce the protective innate immune system to respond to injury, infection, stroke, neurotoxins and trauma. The inflammation is acute and short-lived, which is significant in reducing cellular damage through potential CNS threats neutralization. However, if there is a persistent chronic neuroinflammatory response, it can be detrimental. This could lead to neuronal circuits impairments, neuronal damage, neurodegeneration, and astrocytic and microglia involvement. This occurs through accumulation of neurotoxic proinflammatory mediators and long-lasting formation.

Inflammation of the central nervous system (CNS) involves blood-brain-barrier permeability, increase in glial activation, leukocyte invasion, and concentration of pro-inflammatory cytokine. Interleukin (IL)-1 beta is a key factor in the neuroinflammatory process. Interleukin (IL)-1 beta is a pro-inflammatory cytokine, which is up-regulated in neurodegenerative diseases.

Melatonin is thought to have an effect on several astrocytic functions in most neurodegenerative disorders. However, the mechanism of action on alpha-7 nicotinic acetylcholine receptor (α7-nAChR) and neuroinflammatory cascade is not elaborate. Studies have shown that if C6 cells are treated with melatonin for 24 hours, there will be a significant decrease in the level of oxidative and nitrative stress induced by lipopolysaccharide (LPS). Additionally, there is also reduction of expressions of glial fibrillary acidic protein (GFAP), cyclooxigenase-2 (COX-2) and inducible nitric-oxide synthase (iNOS). Melatonin is believed to have anti-neuroinflammatory action, which may be significant in the neurodegenerative disorders.

NLRP3 Inflammasome is another significant mediator of neuroinflammation in Murine Japanese Encephalitis, which is caused by Japanese Encephalitis virus (JEV). This disorder occurs when there is microglial activation, which leads to pro-inflammatory cytokines synthesis like Interleukin-1α (IL-1α) and Interleukin-1 β (IL-1β). However, it is not clearly understood how the mechanism for the virus identification by microglia works, leading to the generation of the cytokines.

IL-1β cytokine is multifunctional, and plays key roles in both chronic and acute inflammations. It can trigger signal transduction pathways causing the synthesis of more chemokines, pro-inflammatory cytokines, and acute phase proteins resulting in hypertension and fever. Caspase-1 is the key enzyme involved in maturation of both IL-1β and IL-1α. NLRP3 Inflammasome is the primary mediator of the activity of caspase-1 and the synthesis of IL-1α and IL-1β in microglial cells. The activation process of caspase-1 can occur both in vivo and in vitro. Cytokine synthesis and caspase-1 activity reduces when NLRP3 gets depleted. Reactive Potassium efflux and Oxygen Species (ROS) production pose as supplementary danger signals that microglial cells require for the production of IL-1β and IL-1α.

Neurodegenerative diseases are linked with increased levels of various cytokines and chronic neuroinflammation. For example, Aβ1-40 and 1-42 peptides are produced in excess if mutations occur in Amyloid Precursor Protein (APP) or γ-secretase and β-secretase, which make up the processing machinery of APP. In turn, the excess production of these peptides results in Alzheimer’s disease.

Therefore, it is evident that neuroinflammation has a vital role to play in the pathogenesis and development of Alzheimer’s disease. This is further supported by the fact that there is a phenotype of a neurotoxic microglia, which contributes majorly to the pathophysiology of Alzheimer’s disease. Neuroinflammation has both important and detrimental effects on neurodegenerative diseases. Microglia and neuroinflammation have therapeutic effects in preventing and treating neurodegenerative disorders. On the other hand, they contribute to the formation of neurodegenerative disorders. Therefore, researchers should develop therapies that take both factors into consideration. The therapies should eliminate the detrimental effects of neuroinflammation, and at the same time, optimize the good effects of the same.

Nitric oxide (NO) is a gaseous free radical, which is produced from L-arginine by nitric oxide synthases (NOS). NO is mainly produced by macrophages, vascular endothelia and various neurons in the brain. There are three forms of nitric oxide synthases: endothelial NOS (eNOS), inducible NOS (iNOS) and neuronal NOS (nNOS). NO is also produced in the human brain in synaptic terminals by a neuronal isoform of NOS, which acts like a neuromodulator. Both eNOS and nNOS isoforms are constitutive and dependent on calcium-calmodulin, while iNOS is independent of calcium and it is also inducible. The former forms release NO from endothelium and neurons, while the latter is synthesized in immune cells that have been activated. NO has both destructive and protective neuronal action depending on its concentration in the tissues.

NO is involved in various signaling pathways in tissues of mammals, thus referred to as a signaling molecule. It also mediates several pathological and physiologic processes including learning, memory, vasodilation, immune response regulation, and neuronal development. It is also involved in reduction of adhesion and aggregation of platelets. However, vasodilation is the main effect caused by NO.

The role of NO in the brain is to modulate and control the release of neurotransmitters. It also mediates other functions of the brain such as memory function, neuroendocrine secretion, synaptic plasticity and synaptogenesis. In addition, NO also has other roles in the body such as it is involved in the relaxation of blood vessels by the endothelium. It also has a role to play in neurotransmission of peripheral and central neurons and macrophage immune activity. NO also has a detrimental effect when its production is in excess. Overproduction of NO causes neurotoxicity, which is a prime factor in neurodegenerative disorders. Being a free radical, NO causes air pollution because it is emitted by car exhausts, and it is also found in the smoke released by cigarettes. Presence of the gas in the atmosphere causes destruction of the ozone layer and acidic rain. NO has a short life span, which has an advantage in the optimization of localized effects of NO.

NO, as a neurotransmitter, diffuses readily through the cells, in turn activating guanylate cyclase. This is a soluble enzyme, and it converts GTP to cGMP. NO is also easily deactivated to nitrites and nitrates. Some NOS inhibitors are involved in managing neurodegenerative disorders. Unfortunately, there is no effective treatment available to stop activation of microglia and curb the harmful effects of neurotoxic molecules that have the potential to cause brain disorders.

The inducible isoform of nitric oxide synthases, iNOS, is induced in neurons and glia, thus causing Alzheimer’s disease and other neurological disorders. There is up-regulation of argininosuccinate synthase (ASS) enzyme, an iNOS substrate, in the CNS during inflammation. There is also occurrence of excitotoxicity in both chronic and acute forms of neurologic disorders. NO influences the release of glutamate from astrocytes, which is a key contributing factor to excitotoxicity. Excitotoxicity is significant in neurodegenerative diseases development like Alzheimer’s disease.

Occurrence of aggregates of nitrated protein in the human brain is responsible for most cases of neurodegenerative disorders. These aggregates induce nitrosative stress, which leads to neurodegradation. High levels of nitrosative stress results in protein nitration, which in turn causes aggregation of proteins. These protein aggregates are noxious to neurons and cause neurodegenerative diseases. In addition, nitrosative stress could alter several neuroprotective pathways through modification of protein activity by the help of S-nitrosylation. Neurodegeneration may also result from multiple pathways.

During an inflammation, white blood cells or leucocytes accumulate at the infection site and release mediators that activate other cells. Inflammatory mediators have a local action at the site of infection or injury. These molecules are described as being diffusible and soluble, and can be divided into two main categories: endogenous and exogenous mediators. Toxins and bacterial products fall in the exogenous category, and include Gram-negative bacteria’s LPS and endotoxins. Endotoxins can increase vasodilation and permeability through complement activation by means of anaphylatoxins C5a and C3a formation. Moreover, Hageman factor is also activated by endotoxins, resulting in fibrinolytic pathways and kinin system activation. T-cell proliferation is also triggered by endotoxins since they are T-cells superagents.

On the other hand, endogenous mediators trace their origin to both adaptive and innate immune systems. Inactive molecules found in the plasma as fragments of coagulation, kinin and complementary systems can be a source of endogenous mediators. There is also release of inflammatory mediators at the inflammation site by different cells. They could be contained either in storage granules as preformed molecules, for example, histamine. They can also be released when needed by switching on the machinery that synthesizes the mediators, for example, the production of arachidonic acid metabolites.

During an infection or injury, the immune response first responds through inflammation, which is expressed through swelling and reddening of infected area. This is because there is more than usual blood flowing to the injured tissues. Cytokines and eicosanoids are responsible for inflammation. Tissues in the injured areas release the cytokines and eicosanoids. Cytokines are proteins in nature, and they are synthesized by the cells. The role of cytokines is to optimize inflammatory response, and they include interleukins, interferons and chemokines.

Chemokines is an important group of cytokines helpful in mediation of neuroinflammation. They are generally small protein molecules, about 8-10 kDa. They directly stimulate chemotaxis in responsive cells through interaction with transmembrane receptors, which are G protein-linked. These receptors are referred to as chemokine receptors, and occur on the target cell surfaces. There are two types of cytokines: pro-inflammatory chemokines and homeostatic chemokines. Pro-inflammatory chemokines participate in neuroinflammation, while homeostatic chemokines regulate tissue development and maintenance. Pro-inflammatory chemokines recruit certain white blood cells to injured tissues.

Interferons are glycoprotein molecules of low molecular weight that play a role as mediators of the immune system. They prevent viral replication in the infected tissues through a non-specific inhibitory effect. There are three types of interferons: interferon alpha, interferon beta, and interferon gamma. Leucocytes and fibroblasts synthesize both interferon beta and alpha, which are connective tissues. Activated T-cells produce Interferon gamma, which is found naturally in the body. It is actively involved in inflammation. On the other hand, interferon beta works against interferon gamma by regulating its production. It also inhibits immune cells stimulation, and suppresses inflammation by increasing the activity of the lymphocyte. Interferons facilitate cellular communication to stimulate protection mechanisms of the immune system in order to eliminate infections and tumours.

Excess production of some cytokines in the body could cause neurological diseases. For example, rheumatoid arthritis and Alzheimer’s disease occur when tumor necrosis factor-alpha (TNF-α) and interleukin-1 (IL-1) are in excess. This is because these cytokines play a key role in tissue damage and inflammation. However, there is some good news for people ailing from rheumatoid arthritis and AD because researchers have developed therapeutic drugs to treat the disease. These drugs are referred to as non-steroidal anti-inflammatory drugs (NS AIDs), and have an inhibitory effect on TNF-alpha and IL-1, thus reducing the chances of development of Alzheimer’s disease. There is an increase in the levels of Cyclooxygenase 2 (COX-2), in the neuron cells of a patient with AD. COX-2 is a main target of NS AIDs.

The cytokines responsible for inflammation are referred to as pro-inflammatory cytokines. They trigger and alert the immune system during an infection through relay of messages between cells thus provoking an inflammatory response. On the other hand, other cytokines work in the opposite manner as the pro-inflammatory cytokines, and they are known as anti-inflammatory cytokines. Their role is to minimize the level of inflammation at the site of injury, and facilitate the healing process. However, the two types of cytokines work in a balanced way in body functions.

Interleukins are chemicals occurring naturally, and are proteins in nature. They are a member group of cytokines, which relay messages between cells. The role of interleukins is to regulate cell differentiation, growth, and motility. They also trigger the immune system during an inflammation, and control white blood cells communication. Upon production by the white blood cells, interleukins find their way to an infected cell. They bind to the cell through a receptor molecule occurring on the cell surface. Consequently, cellular behavior changes due to various signals produced following the interaction.

There are fifteen known types of interleukins, and they are denoted using numbers, IL-1 to IL-15. IL-1 and IL-2 mainly activate B and T lymphocytes in order to trigger an immune response. IL-2 stimulates the growth and maturation of B and T cells, while IL-1 together with IL-6 trigger inflammation. IL-4 causes B-lymphocytes to stimulate antibody secretion, and IL-12 influences the production of a large number of natural killer cells and cytotoxic T cells.

The main cytokines found in high levels in the brain of a patient suffering from AD are tumour necrosis factor (TNF) α), interleukin (IL)-1 α, IL-1 β and IL-6. IL 1 is made up of several components including isoforms IL-1 α and IL-1 β, which are secreted, IL-1R1 and IL-1RII, which are transmembrane receptors. IL-R1a is a naturally occurring antagonistic receptor of IL-1. IL-1 α and IL-1 β up-regulate hematopoiesis, immune responses and inflammation. Besides inflammation, IL-1 has added roles such as regulating appetite, inducing fever, secretion of insulin, development of neuronal phenotype, and involved in bone formation.

Both IL-1 α and IL-1 β are produced as a polypeptide of 31-33 kilo Dalton (kDa), as pro-cytokines that are enzymatically cleaved and glycosylated. Their precursor structure contains 25% of amino acid, and the mature parts contain 22% of amino acid (aa). IL-1 α is 271 aa long while IL-1 β is 269 aa in length. IL-1 β is divided into a 153 aa and 116 aa pro-segments, of a 17 kDa mature segment. On the other hand, IL-1 α is divided into a 112 aa pro-sequence and 159 aa mature segment of a bio-active 17 kDa. IL-1 α is the bio-active isoform of IL-1 while IL-1 β is an inert molecule. During an injury, IL-1 α and IL-1 β are the main role players since they offer neuroprotection via signaling with the antagonistic receptor, IL-R1a, by offering an inhibitory effect.

In case of a brain injury, microglia release IL-1 α to offer neuroprotection within a given time frame. Studies conducted on mice indicate that the neuroprotective effects of IL-1 α diminish after three hours have elapsed before administration is initiated. In most cases, there is development of sterile inflammation, which is a vital factor in injury and disease development. A brain cell injury is considered sterile when there is shortage of blood supply to the brain. Therefore, IL-1 α has a major significance in the development of sterile inflammation and not IL-1 β. IL-1 β stimulates the human neuroblastoma cell line SK-N-SH to secrete prostaglandin PG E2, and trigger the immunoreactivity of COX-2. COX-2 neuronal induction is linked to the advancement of Alzheimer disease. In the brain of a patient with AD, there are elevated levels of COX-2. The human neuroblastoma cells SK-N-SH express APP stably. Experimentally, the cells were treated with PGE2, and they expressed high amounts of Aβ. This clearly indicates that PGE2 is a stimulant in Aβ production. Therefore, PGE2-stimulated Aβ production is significant in the inflammation-triggered AD development. However, PGE2 secretion is dependent on arachidonic acid availability. Prostaglandins have some roles to play in the CNS including controlling the sleeping pattern, pain perception and fever initiation. Therefore, IL-1 β stimulate the expression of COX-2 and the secretion of PGE2. In addition, IL-1 β also has a crucial role to play in in vivo acute inflammation.

Alzheimer’s disease is pathologically defined by neurofibrillary tangles and senile plaques accumulation, which constitute of peptide components of Amyloid beta (Aβ). These components activate microglia, and induce the death of neuronal cells. Therefore, there are high levels of Aβ components in AD patients’ brain cells. PGE2 is a significant neuroinflammatory inducer, and has a significant role in stimulating Aβ in human neuroblastoma cell line SK-N-SH. Under normal circumstances, microglia activation occurs in order to trigger inflammatory and immune responses in the CNS. However, if the microglia are abnormally activated, there is injury of the CNS. This is through stimulation of cytotoxic and pro-inflammatory factors, which include iNOS, TNF-α, IL-1 β and COX-2. TNF-α, IL-1 and IL-6 are involved in formation of neurofibrillary tangles and senile plaques, and they are upregulated in the brain of an AD patient.

Lipopolysaccharide (LPS) is a constituent of Gram negative bacteria cell wall. It is an immunostimulant in that it triggers inflammatory response in the brain. LPS contributes to inflammation by inducing the pro-inflammatory cytokines such as IL-1 and NO in macrophages, particularly microglia. IL-1 and NO synthesis facilitate microglia cells activation by LPS. Atrial natriuretic peptide (ANP) inhibits microglial activation by LPS. LPS activates the microglia through the aid of proinflammatory transcription factors namely activator protein 1 (AP-1) and nuclear factor kappa beta (NF-ҡβ) and AP-1. In microglia cells stimulated by LPS, the activities of NF-ҡβ and AP-1 are beefed, but they are suppressed by ANP. Consequently, inflammation rates are reduced following this suppression by ANP. Therefore, ANP also inhibits the activities triggered by LPS in microglia since ANP receptors are activated. This leads to suppression of the proinflammatory transcription factors, AP-1 and NF-ҡβ. In AD neuroinflammation, microglia cells play a significant mediation role.

Dially disulphide (DADS) exhibits an anti-inflammatory characteristic. Studies have exhibited that DADS possesses a therapeutic characteristic in BV2 microglia that are induced by LPS. DADS has an inhibitory effect in suppressing the production of PGE2 and NO excessively. In turn, this suppression leads to down-regulation of iNOS, and reduced expression of COX-2. In addition, DADS also suppresses the expression of the mRNAs of cytokines and pro-inflammatory cytokines. In turn, NF-ҡβ is down-regulated, and MAPK signaling pathway is inactivated. Therefore, DADS possesses a neuroprotective effect and it is used in treating neurodegenerative diseases including Alzheimer’s disease.

BV2 cells are immortalized murine microglia, and the preferred choice of cell lines to replace primary microglia (PM) in vitro. They have common features with PM, but their suitability is questionable since gene up-regulation is reduced. However, they regulate NO generation and respond to interferon gamma in the normal way. In addition, they also trigger other glial cells, stimulate NF-ҡβ translocation, and mediate the synthesis of IL-6 in astrocytes. Experimentally, BV2 cells have proved to be viable PM substitutes in vivo.

NF-ҡβ is a transcription factor in mammals, which is protein in nature. It regulates about 150 genes, and controls inflammation in the human body. Inflammation in most tumour cells is expressed when NF-ҡβ is activated. NF-ҡβ mediates the activation of BV2 microglia cells by LPS, causing endothelial cells injury. Thus, BV2 microglia that have been activated by LPS are cytotoxic. In addition, NF-ҡβ is therapeutically important in brain pathological disorders including AD. Activation of NF-ҡβ and other transcription factors results in the up-regulation of iNOS, an immune molecule. This, in turn, leads to the generation of NO. NF-ҡβ up-regulates various transcription factor pathways, which take part in the generation of NO by BV2 microglia. Another inhibitor of iNOS, sauchinone, also inhibits the upregulation of NO and PGE2 production by BV2 cells. It suppresses the expression of iNOS, TNF-α, COX-2 and IL-1β, thus, preventing inflammation in activated microglia.

Beta glucan, a biological response modifier (BRM), also possesses therapeutic characteristics through immune stimulation activation via macrophages. In LPS induced BV2 cells, there is a decrease in the generation and expression of TNF-α. Moreover, beta glucan also inhibits the activation of NF-ҡβ by LPS induced microglia. Therefore, suppression of LPS induced TNF-α production occurs through inhibition of NF-ҡβ in BV2 cells.

Patients suffering from the non-curative AD and other neurodegenerative disorders experience an increased rate of release of proinflammatory cytokines such as TNF-α. This, in turn, triggers the generation of NO, which is a key mediator in inflammation. NO has a therapeutic advantages in management of Alzheimer’s disease. However, if there is an abnormality in the signaling of NO in the body, various neurodegenerative diseases could result, including AD. This indicates that excess levels of NO in the brain cause toxicity, and consequently death of neuronal cells. Availability of a vascular risk factor in the body interferes with the normal release of NO, and in combination with age advancement, the risk factor has an immense immensely to the pathogenesis of AD.

On the other hand, studies have indicated that TNF-α is the primary initiator of most cases of neuroinflammation in various organs of the body, the brain included. Therefore, TNF-α has a key role to play in the pathological characteristics of AD. Etanercept is an anti-inflammatory agent that has been widely used in the attempt to come up with treatment for AD. It has the ability to inhibit TNF-α’s biological activity in contributing to AD, thus used as a therapeutic agent in AD, with credited approval form the US Food and Drug Administration (FDA).

Punica granatum is the scientific name for pomegranate an ancient edible fruit of immense health significance. It possesses anti-allergic, antioxidant, antibacterial and anti-inflammatory characteristics, thus widely used as a therapeutic agent. The fruit has various components including leaves, peel, seeds and juice, but the anti-inflammatory and anticancer features originate from the juice or water extract. Pomegranate contains bioactive components like flavonoids, phenolic acids, and tannins, which could have anti-inflammatory benefits. Flavonoids protect the brain against neurotoxicity, and are also helpful in neuroinflammation suppression.

Studies have been conducted to investigate the anti-inflammatory effects of standardized pomegranate rind extract (SPRE) through inhibition of NO. The anti-inflammatory characteristics were determined by measuring the inhibition of NO generation by murine RAW264.7 cells. In this study, RAW264.7 cells, which resemble macrophages, were cultured in RPMI medium. Other supplements constituted in the medium include 100 units/ml of penicillin G, 10% of FCS, 0.1% sodium bicarbonate, 100 lg/ml streptomycin and 2 mM glutamine. Harvesting of the RAW264.7 cells was then done using trypsin–EDTA, and then diluted in fresh media into a suspension. Next, there was cell-seeding in 96-well plates, left to adhere for about one hour at 37° C in a carbonated chamber. The medium was then incubated for 48 hours at a temperature of 37° C, together with the samples being tested. Determination of NO generation was done using Griess reagent by determining nitrite accumulation in the supernatant of the culture. The MTT colorimetric method was used to analyze the level of cytotoxicity in the test samples.

The Griess Reagent system determines the amount of NO produced through measurement of nitrite. Griess system mainly utilizes two solutions namely N-1 napthylethylediamine dihydrochloride (NED) and sulfanilamide solutions, in the presence of phosphoric acid. Griess systems detects nitrite levels in biological fluids including culture media, and the sensitivity of nitrite is dependent on the matrix of 50ml NED solution, 50 ml sulfanilamide solution, and 1ml Nitrite Standard. However, maximum nitrite sensitivity is attained when the solutions are sequentially added. First, sulfanilamide solution is added and incubated for 5-10 minutes, and then NED is added last.

Pomegranate water extract (PWE) influences the inhibition of iNOS, NO production, the release of cytokines and COX-2 expression, which contribute immensely to microglia stimulated neuroinflammation. MAPK signaling pathway regulates these processes, and PWE has the ability to inhibit the pathway to prevent iNOS and COX-2 expression. In addition, PWE influences the down streaming of pro-inflammatory transcription factors like NF-ҡβ, which contribute to neuroinflammation. Therefore, PWE has an inhibitory effect on NO, TNF-α and IL-1β and production that trigger neuroinflammation.

In conclusion, Alzheimer’s disease is a popular form of dementia in the elderly, and is mainly caused by neuroinflammation. There are various factors that contribute to inflammation such as excessive synthesis of IL-1 and TNF-α. TNF-α is the primary initiator of most cases of neuroinflammation. Activation of NF-ҡβ is another contributing factor to neuroinflammation since it acts as a mediator in activating BV2 cells by LPS, leading to cell injury. BV2 cells are microglial cells, which have an important mediation role in inflammation. LPS-induced microglia contribute to inflammation by inducing the pro-inflammatory cytokines such as IL-1 and NO in macrophages.

However, they are some inhibitory factors that are useful in the treatment of AD. These factors inhibit the expression and activation of neuroinflammatory mediators. These include PWE, which inhibits iNOS, NO production, the release of cytokines and COX-2 expression, which contribute immensely to microglia stimulated neuroinflammation. Etanercept is also an anti-inflammation agent that inhibits the activity of TNF-α, which is major factor in AD development. Sauchinone is another inhibitory agent that suppresses the expression of iNOS, TNF-α, COX-2 and IL-1β, thus, preventing inflammation in activated microglia. DADS is also an anti-inflammatory agent that has neuroprotective benefits, thus used in treatment of neurodegenerative diseases including Alzheimer’s disease. NO has a therapeutic advantages in management of Alzheimer’s disease, but its production in excess leads to toxicity and neuronal cell death.