MEDICINAL PLANTS IN NEURODEGENERATIVE DISEASE -A REVIEW

www.wjpps.com │ Vol 10, Issue 7, 2021. │ ISO 9001:2015 Certified Journal │

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Prathiba et al. World Journal of Pharmacy and Pharmaceutical Sciences

MEDICINAL PLANTS IN NEURODEGENERATIVE DISEASE -A

REVIEW

Prathiba H. D.*1 and Padmashree D.

2

1Department of Biochemistry, Jnana Bharathi Campus Bangalore University, Bangalore-

560001, Karnataka, India.

2Department of Biochemistry, Jnana Bharathi Campus Bangalore University, Bangalore-


ABSTRACT

Neurodegeneration denotes to a condition of neuronal death arising as

a result of advanced disease of long-term and is becoming a major

health problem in the 21st century. Neurons degenerated are not

substituted resulting in a cognitive loss, many neurodegenerative

disorders, such as cerebrovascular impairment, seizure disorders, head

injury, parkinsonism. The common pathology of neurodegeneration

includes deposition of misfolded proteins such as amyloid-β in

Alzheimer‟s disease, α-synuclein in Parkinson's disease, transactive

response DNA-binding protein 43 (TDP-43) in dementia.

Neuroprotection refers to the approaches and possible mechanisms that

are able to defend the central nervous system against neuronal injury

and neurodegenerative disorders. The past span has witnessed an intense interest in herbal

plants having long-term medicinal qualities. Widespread research and discovery have

demonstrated that natural products, medicinal herbs, plant extracts, and their metabolites,

have great potential as the neuroprotective agent. Although the accurate mechanisms of

action of herbal drugs have yet to be resolute, some of them have been shown to prevent

formation of beta-amyloid plaques, stimulate nerve growth, some inhibit acetylcholinesterase

enzyme and malondialdehyde development in brain while other shows antioxidant activity by

increasing the level of superoxide dismutase, catalase, glutathione peroxidase. Thus the

herbal plants can be a valuable source of the drug against neurodegenerative disorders which

will require high-throughput screening. This review will highlight the role of herbal plants

and their phytoconstituents against neurodegenerative diseases and other related disorders.

WORLD JOURNAL OF PHARMACY AND PHARMACEUTICAL SCIENCES

SJIF Impact Factor 7.632

Volume 10, Issue 7, 568-582 Review Article ISSN 2278 – 4357

*Corresponding Author

Dr. Prathiba H. D.

Department of

Biochemistry, Jnana

Bharathi Campus Bangalore

University, Bangalore-


Article Received on

29 April 2021,

Revised on 19 May 2021,

Accepted on 08 June 2021,

DOI: 10.20959/wjpps20217-19305


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KEYWORDS: Alzheimer‟s disease, Amyloid-β, Antioxidant, Dementia, Herbal medicine,

Neurodegenerative diseases, Neuroprotective.

INTRODUCTION

Millions of people worldwide are affected with neurodegenerative diseases every year. The

number of people affected by Alzheimer‟s disease alone increased from 26.6 million in the

year 2006 to 36 million in the year 2018, out of which 5.1 million are Americans of all ages,

of which 200,000 are under age 65 (younger- onset Alzheimer‟s).[12]

The cost for

neurodegenerative disease treatment is very high; more than $100 billion is spent every year

for Alzheimer‟s disease. Neurodegenerative diseases are categorized by the progressive

damage and dysfunction of the neurons or the nerve cells.[3]

Neurodegenerative disease

origins regarding protein degradation, various environmental factors, mitochondrial defects

and abnormal protein accumulation in neurons etc. however aging is considered as one of the

major problems in neurodegenerative diseases.

Over the past few decades, a large number of progressive technologies have been developed

in order to specifically carry huge number of different compounds and bioactive molecules to

mitochondria. These technologies have allowed a significant step forward in terms of

enhancement of drug pharmacokinetic profile, intracellular penetration, distribution at the

target site, and improvement of the pharmacological effects. Exact attention has been given to

the expansion of useful drug delivery systems consisting in nano-sized materials (1–100 nm)

which has the capability to cross numerous biological barriers, to protect the drugs from

premature deactivation thereby improving their pharmacokinetic profile, and also to increase

the internalization and distribution of the molecules of interest at the target site. Many efforts

have been made in order to propose nano-drug delivery systems, which possess these specific

characteristics. Despite several promising findings in nano-drug delivery systems represents

still new research area required for further extensive investigations and analysis. Herbal

medicines make up a significant component of the trend toward alternative medicine. Herbal

medicine is becoming ever more popular in today‟s world as people seek out natural

remedies.[9]

Herbal medicines have been used since the dawn of civilization to maintain

health and to treat various diseases.


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4. Standardization and Stability testing of Herbal Drugs

Standardization of Herbal Drugs

Herbal drugs imply knowledge and practice of herbal healing for the prevention, diagnosis,

and elimination of physical, mental, or social imbalance.[15]

The costs for health care are

rising at an alarming rate throughout the world. At the same time, the world market for

phytopharmaceuticals is growing progressively. The World Bank estimates that trade in

medicinal plants, botanical drug products, and raw materials are growing at an annual rate of

between 5 and 15 %.[16,17]

It is a common observation that people diagnosed with incurable

chronic disease states such as diabetes, arthritis, and AIDS turned to herbal therapies for a

sense of control and mental comfort from taking action.[13]

Herbal product studies cannot be

considered scientifically valid if the product tested has not been authenticated and

characterized in order to ensure reproducibility in the manufacturing of the product in

question. Several studies have indicated quantitative variations in marker constituents in

herbal preparations. Moreover, many dangerous and lethal side effects have recently been

reported, including direct toxic effects, allergic reactions, effects from contaminants, and

interactions with drugs and other herbs. Standardized herbal products of consistent quality

and containing well-defined constituents are required for reliable clinical trials and to provide

consistent beneficial therapeutic effects. Pharmacological properties of an herbal formulation

depend on phytochemical constituents present therein. Development of authentic analytical

methods which can reliably profile the phytochemical composition, including quantitative

analyses of marker/bioactive compounds and other major constituents, is a major challenge to

scientists. Without consistent quality of a phytochemical mixture, a consistent

pharmacological effect is not expected. Resurgence of interest and the growing market of

herbal medicinal products necessitate strong commitment by the stakeholders to safeguard

the consumer and the industry. Standardization is the first step for the establishment of a

consistent biological activity, a consistent chemical profile, or simply a quality assurance

program for production and manufacturing. Therefore, the EU has defined three categories of

herbal products.

Those containing constituents (single compounds or families of compounds) with known

and experienced therapeutic activity that are deemed solely responsible for clinical

efficacy.

Those containing chemically defined constituents possessing relevant pharmacological

properties which are likely to contribute to the clinical efficacy.


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Those in which constituents have been identified has being responsible for the therapeutic

activity.

Standardization as defined in the text for guidance on the quality of herbal medicinal products

means adjusting the herbal drug preparation to a defined content of a constituent or group of

substances with known therapeutic activity. The European Medicines Agency (EMEA)

makes the distinction between constituents with known therapeutic activity which can be

used to standardize a biological effect and marker compounds which allow standardization on

a set amount of the chosen compound. The EMEA defines marker compounds as chemically

defined constituents of a herbal drug which are of interest for control purposes, independent

of whether they have any therapeutic activity or not. Examples of markers are the valerenic

acids in Valeriana officinalis L., gingkolides and flavonoids in Ginkgo biloba L. and

hypericin and hyperforin in Hypericum perfoliatum L.[10, 18]

The purpose of a stability testing

is to provide proof on how the quality of the herbal products varies with the time under the

influence of environmental factors such as temperature, light, oxygen, moisture, other

ingredient or excipients in the dosage form, particle size of drug, microbial contamination,

trace metal contamination, leaching from the container and to establish a recommended

storage condition and shelf-life. Stability testing is necessary to ensure that the product is of

satisfactory quality throughout its entire storage period. Stability studies should be performed

on at least three production batches of the herbal products for the proposed shelf-life, which

is normally denoted as long term stability and is performed under natural atmospheric

conditions. Stability data can also be generated under accelerated atmospheric conditions of

temperature, humidity and light, which is referred to as short term stability and the data so

obtained is used for predicting shelf-life of the product. Stability testing should be conducted

on the dosage form packaged in the container closure system proposed for marketing. With

the help of modern analytical techniques like spectrophotometry, HPLC, HPTLC and by

employing proper guidelines it is possible to generate a sound stability data of herbal

products and predict their shelf-life, which will help in improving global acceptability of

herbal products.

Pharmacovigilance of Herbal Drugs

Pharmacovigilance is the science and activities relating to the detection, assessment,

understanding and prevention of adverse effects of drugs or any other possible drug-related

problems. Recently, its concerns have been widened to include: herbals, traditional and


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complementary medicines, blood products, biological, medical devices and vaccines.[24]

The

aims of pharmacovigilance is to protect patients from unnecessary harm by identifying

previously unrecognized drug hazards, elucidating pre-disposing factors and quantifying risk

in relation to benefits.[25]

The purpose of pharmacovigilance is to detect, assess and nderstand

to prevent the adverse effects or any other possible drug-related problems, related to herbal,

traditionally and complementary medicines.[20]

Herbal drugs are broadly used in both

developed and developing countries however, in current years, there are several high-profile

herbal safety concerns having an impact on the public health. Herbal drugs are traditionally

considered as harmless but as medicinal products they require drug observation in order to

identify their risks. Published data shows that the risk is due either to a contaminant or to an

added drug. Tremendously limited knowledge about the constituents of herbal drugs and their

effects in humans, the lack of rigorous quality control and the heterogeneous nature of herbal

drugs necessitates the continuous monitoring of the safety of these products. WHO has

increased its efforts to promote herbal safety monitoring within the background of the WHO

International Drug Monitoring Programme. The WHO guidelines aim to propose the member

states of a frame work for facilitating the regulation of herbal medicines used in traditional

medicine covering issues like classification, assessment of safety, assessment of the efficacy,

quality assurance, pharmacovigilance and control of advertisements of herbal drugs products.

The pharmacovigilance of herbal medicines exhibits particular challenges because such

preparations are available from a wide range of outlets typically where there is no health care

professional available, most purchases are in conventional OTC environment. Various

methods in pharmacovigilance are passive observation includes impulsive reporting and

stimulated reporting, active surveillance by sentinel sites, drug event monitoring, registries,

comparative observational studies by survey study, case control study, targeted clinical

investigations by investigate drug-drug interactions and food-drug interactions.[24]

The

importance of genetic factors in determining an individual vulnerability to adverse drug

reactions is well documented and this implies to herbal medicines as well as to conventional

drugs. Pharmacovigilance is therefore one of the important post-marketing safety tools in

ensuring the safety of pharmaceutical and related health products.[14]

Regulatory Status of Herbal Drugs

The lawful situation of herbal drugs varies from country to country. Developing countries

have folk knowledge of herbs and their use in traditional medicine is wide spread. But, these

countries do not have any lawmaking criteria to include these traditionally used herbal drugs


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in drug legislation.[30]

Endorsement of herbal drugs in most countries is based on traditional

herbal references, provided they are not known to be unsafe when used to treat slight

illnesses. But, now-a-days claims are being made to treat more serious illnesses with herbal

drugs for which no traditional knowledge is present.[23]

Therefore, narrow requirements for

herbal drugs are necessary to ensure the safety, efficacy and quality and to support specific

indications; scientific and clinical evidence must be acquired. Depending upon the nature of

herbs and market availability, different requirements exist for submission of clinical trial data

and toxicity data. The regulatory requirements of herbal drugs is varies from one country to

other country. Some countries accept traditional, experience based evidence while some

consider herbal remedies as dangerous or of questionable value.

Fig. 1: Natural compounds with neuroprotective effect.

Challenges in the use of natural compounds in the nanosize range Parkinson‟s disease (PD)

mainly affects the motor system of the brain. The death/dysfunction of dopamine generating

cells are the root cause for the disease. A cascade of events lead to the outbreak of the

disease; namely oxidative stress, mitochondrial dysfunction, misfolding during protein

synthesis, excitotoxicity by various biochemical pathway (glutamate pathway), lysosome

impairment and autophagy by chaperone and the formation of Lewy bodies due to protein

misfolding takes place which lead to disease condition. Lewy bodies are made up of

neurofilament protein and ubiquitinated α-synuclein (Fig. 1). Braak‟s staging illustrates that

the lewy bodies are usually found in the olfactory region and in the lower region of the brain

stem; but as the disease progresses the Lewy bodies reach the substantia nigra of midbrain

and forebrain; and in advance stage it reaches the neocortex region of the brain. A study by

Hughes et al.[30]

revealed that certain neuronal undergo a field change due to widespread lewy

https://link.springer.com/article/10.1007/s40898-017-0004-7/figures/1


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body distribution. They suggest that a field change is commonly observed in tyrosin

hydroxylase synthesizing cells. Among the big list of neurodegenerative diseases such as

Acute disseminated encephalomyelitis, Creutzfeldt–Jakob disease, Epilepsy and Epileptic

syndrome, Gerstmann–Straussler–Scheinker disease, Juvenile neuronal ceroid lipofuscinoses,

Kuru (prion disease), Leukodystrophies, Machado–Joseph disease, Multiple sclerosis,

neurodegeneration in Diabetes Mellitus, Neurofibromatoses, Pick‟s disease, Tourette

syndrome.; Parkinson‟s, Huntington and Alzheimer‟s disease are associated with aging and

are widely studied over the past few decades.

Fig. 2: Molecular pathogenesis in neurodegenerative diseases.

https://link.springer.com/article/10.1007/s40898-017-0004-7/figures/2


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Similar to Parkinson‟s disease, another commonly found neurodegenerative disease in the

elderly is Alzheimer‟s disease (AD). Age is a major risk factor for neurodegenerative disease

as the person slowly losses the ability of self-repair. Alzheimer‟s disease can be classified as

familial/genetic and sporadic AD. In genetic/familial AD disease condition starts at a very

young age; on the other hand sporadic AD occurs in elderly person. The disease is an

outcome of mutation in amyloid precursor protein (Fig. 2). Hebert et al.[13]

investigated the

change in microRNA expression and observed that miRNA is involved in APP regulation and

there was a decrease in BACE1 expression in sporadic disease condition. The study also

suggests that the increase in BACE1 and Aβ level is due to the loss of specific miRNAs.

Huntington‟s disease (HD) named after George Huntington is said to be caused by genetic

mutation in the genes of chromosome 4. The disease is characterized by moment disorder

generally occurs in the fourth or fifth decade of a person‟s life and tend to progress for 10–

20 years later. The disease rarely found in juveniles, where the symptoms are more severe

including rigidity.[34]

This autosomal disease is an outcome of elongated CAG (cytosine,

adenine, and guanine) repeat (Fig. 2); the onset of the disease thus depends on the length of

the CAG repeat. Huntingtin a mutant protein results from CAG repeats, this in turn leads to

polyglutamic strand at the N-terminus.[29]

The symptoms vary among individual, however

mental instability/behavioral abnormality is one of the common symptom of Huntington‟s

disease. A recent study indicated that CA2+

loading in mitochondria is drastically high in HD

cells even under resting state. This high CA2+

loading is the root cause of mitochondrial DNA

damage which further leads to mitochondrial dysfunction in HD cells. Neuropathogenesis of

Huntington‟s disease is characterized by atrophy of various regions in the brain such as the

caudate nucleus, putamen, and segments of globus pallidus in the initial stage; as the disease

progresses the atrophy occurs in the regions such as cerebellum, cerebral cortex, thalamus,

and cerebral white matter. Moreover, other issues like oxidative stress, dysfunction in

metabolic activity and genetic mutation are also said to be responsible for neuronal damages

and cell death.

Medicinal plants commonly used for neurodegenerative diseases

Neuroprotective treatments are practices designed to interrupt the cellular, biochemical, and

metabolic explanation of injury during or following contact to ischemia; they incorporate a

rapidly expanding array of pharmacologic interventions. Neuroprotective agents refer to

constituents that are accomplished of preserving brain function and structure by reducing and

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https://link.springer.com/article/10.1007/s40898-017-0004-7#Fig2



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preventing oxidative stress, mitochondrial dysfunction, and inflammation, various forms of

neurotoxicity and protein deficiencies.[13]

Exact examples of things that can cause

neurodegeneration include: traumatic brain injuries, drug abuse, pharmaceutical medications,

strokes, and dementia but the most common cause of neurodegeneration is oxidative stress

and to prevent the effects of any neurodegeneration, considering neuroprotective agents may

be beneficial for long-term brain health. Direction of a neuroprotective agent may help

minimize the effects of chronic conditions that could: kill brain cells, decrease brain volume,

and lead to long-term functional impairment.[16]

There are more than 120 traditional

medicines that are being used for the therapy of Central never system disorders in Asian

countries.[10]

Protein aggregation, inflammation, excitotoxicity, oxidative stress, and

neurotoxicity have been implicated in the pathophysiology of NDs. In the Indian system of

medicine the following medicinal plants have shown promising activity in neuro-psycho-

pharmacology.

Acorus calamus

Acorus calamus (Sweet flag) belonging to family Araceae, act as a rejuvenator for the brain

and nervous system having beneficial memory enhancing the property, learning performance,

and behavior modification. Acorus calamus contains a majority of α-and β-asarone, β-asarone

has the capability of suppressing beta-amyloid-induced neuronal apoptosis in the

hippocampus by reversal down-regulation of Bcl-2, Bcl-w, caspase-3 activation and c-Jun N-

terminal kinase (JNK) phosphorylation.[11]

Methanolic extracts of the roots containing α-

asarone showed inhibitory effect on AChE with an IC50 value of 188µg/ml.[12]

Acorus

calamus has the potential of improving the function of dopaminergic nerve; by increasing

striatal extracellular dopamine level and the expression of tyrosine hydroxylase in

substanianigra therefore it can play role in PD. Acorus calamus also increases DJ-1 gene

expression in the striatum and therefore acts as neuroprotective for PD.[13]

Bacopa monnieri

Bacopa monnieri (Linn), commonly referred to as “Brahmi,” from the plant family

Scrophulariaceae is a creeping herb found in India and neighbouring tropical countries.

Steroidal saponins and bacosides A and B are the active chemical constituents responsible for

improving both learning and memory.[22]

Other constituents include bacopa saponins D, E

and F as well as alkaloids, flavonoids, and phytosterols.[23]

Bacoside A increases the activities

of superoxide SOD, CAT, GPx, and glutathione reductase (GSR). As a result, the levels of


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glutathione (primary endogenous antioxidant conjugate) in the brain are significantly

increased. Bacoside A inhibits lipid peroxidation by modulating the effects of enzymes like

Hsp 70 and cytochrome P450 in the brain. It also improves the activities of adenosine

triphosphatases (ATPases), maintains ionic equilibrium and restores zinc and selenium levels

in the brain. The researchers found Bacopa monnieri produce a reduction in alpha-synuclein

protein aggregation. Bacopa monnieri also enable the body to better cope with the deleterious

mental and physical consequences of stress by elevating levels of noradrenaline (NA),

dopamine (DA) and 5-hydroxytryptamine (5-HT) in the cortex and NA and 5-HT in the

hippocampus.[24]

Jadiya et al. investigated the effect of Bacopa monnieri on

pharmacologically induced 6-hydroxydopamine (6-OHDA) PD model in

Caenorhabditiselegans which expressed human version of alpha-synuclein. The researchers

found that the extract showed a significant 3.5-fold reduction in alpha-synuclein protein

aggregation, which may be due to induction of the stress-buffer protein Hsp-70.[25, 26]

Centella asiatica

Centella asiatica belonging to family Apiaceae (Umbelliferae) has been demonstrated to

possess the neuroprotective property and is used as an alternative medicine for memory

improvement in the Indian Ayurvedic system of medicine for a long time.[27]

The primary

active constituents of Centellaasiatica are saponins (also called triterpenoids), which include

asiaticosides, in which a trisaccharide moiety is linked to the aglyconeasiatic acid,

madecassoside and madasiatic acid. Other components isolated are brahmoside and

brahminoside, which may be responsible for CNS action.[28]

Centella asiatica exhibits potent

antioxidant activity, capable of scavenging free radical, reduces ferric ions, restores GSH

levels by increasing the glutathione-S-transferase activity. Centella asiatica also decreases

Aβ deposition in the brain. Chen et al. carried out a study which suggested that Centella

asiatica ethanol extract can suppress Aβ-induced neurotoxicity by enhancing the

antioxidative defence system in differentiated PC12 and IMR32 cells.[29, 30]

Amelioration of

the colchicine-induced decrease in AChE activity and inhibition of nitric oxide induced

neuronal damage by asiaticoside may also explain the neuroprotective effect of Ce.

Ginseng

Ginseng/panax inseng is a medicinal herb of Korean and Chinese origin. This herb is known

for its medicinal properties for many years. The herb is used for treating diseases such as

cancer, neurodegenerative disorder, hypertension and diabetes. Ginseng is also reported for


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its immune boosting ability and thereby resists illness. Nah et al.[30]

studied on Ginseng which

has the ability to inhibit voltage dependent Ca2+

channels by a receptor linked to G protein

which is sensitive to toxin. The study revealed that Ginsenoside a saponin which is found in

trace amount helps in modulating neuronal Ca2+

channels. Researchers have investigated on

the immune modulatory effect of Ginseng. The inhibitory activity of a metabolite of Ginseng

(compound K) is to be more potent than commercial anti-allergic drugs.[29]

The Ginsenosides

(Rb1 and Rg3) of Ginseng possess neuroprotective effect thereby making them an excellent

compound for treating neurodegenerative diseases. The active compound of P.ginseng, is

proven for its neuroprotective effect on dopaminergic neurons by inhibiting the elevation of

nigral iron level, lowering the expression of DMT1 (divalent metal transporter) and

potentially increasing the expression of FP1 (ferroportin) in Parkinson‟s disease. Chen et al.

suggested that Rg1 reduces the ROS (reactive oxygen species) production by dopamine,

release of cytochrome c into the cytosol, inhibition of caspase 3 activity, and lowers the NO

production by reducing the inducible nitric oxide (NO) synthase protein level. Rg1 is also

reported for its activity in reducing cell injury by hydrogen peroxide by down-regulating NF-

KB signaling pathway and activation of Akt and ERK.

Hypericum perforatum

Hypericum perforatum is a member of the family Hypericaceae. Hypericum perforatum, is

also known as hypericum or millepertuis. Even though it has a worldwide distribution, it is

mainly native to Europe, western Asia, Europe and northern Africa. Hyperoside is the main

active factor of H.[22]

perforatum. Biapigenin, Hypericin, quercetin, Kaempferol are its other

constituents. Hypericum perforatum extract has also been described to protect against

enzymatic (NADPH-dependent) and non-enzymatic (Fe2+

/ascorbate dependent) lipid

peroxidation in the cerebral cortex. The extract also protects brain cells from glutamate-

induced cytotoxicity by reducing glutathione loss, calcium overload and ROS-mediated cell

death. Hypericum perforatum ethanolic extract may improve microglial viability by reducing

amyloid-beta mediated toxicity in Alzheimer‟s disease.[19]

Hypericum perforatum inhibits

acetylcholinesterase enzyme and MDA formation in the brain and increases the level of SOD,

CAT, GPx. According to these findings, Hypericum perforatum also act as an antioxidant and

have the ability to bind iron ions and have scavenging action for hydroxyl radical.




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Melissa officinalis

Melissa officinalis L. belongs to the family Lamiaceae, and it is also known as lemon balm,

are used in traditional medicine for its nerve calming and spasmolytic effects. The leaves

produce calming and soothing effects through GABAA benzodiazepine receptor.[13]

Its

extracts contain some compounds such as flavonoids such as quercitrin as well as apigenin,

luteoline and phenolic acids. These derivatives inhibit enzymes monoamine oxidases and

AChE, scavenge these free radicals and prevent apoptosis.[19]

The inhibition of these enzyme

leads to improvement of depression symptoms. Research also suggests that Melissa officinalis

employ protective activities in the PC12 cell line and might protect neurons from oxidative

stress.

Ocimum sanctum

Ocimum sanctum, belongs to family Labiatae,also known as „Tulsi‟ in Hindi and „Holy Basil‟

in English. The plant is also defined to contain saponins, tannins, alkaloids and glycosides,

vitamin C, and maleic acid, citric and tartaric acid.[11]

A research conducted by Kusindarta et

al. directed that an ethanolic extract derived from leaves of Ocimum sanctum may stimulate

and restores the expression of choline acetyltransferase in ageing human cerebral

microvascular endothelial cells and could deliver nerve protection and increased production

of Ach may enhance the memory and cognitive ability.[18]

Scientific studies reveal that the

hydroalcoholic extract of Ocimum sanctum exhibits strong antioxidant ability against DPPH

and hydroxyl radicals which may be due to the high amount of flavonoids and polyphenols. It

inhibits lipid peroxidation, DNA damage, ROS generation and membrane depolarization.[23]

It also declines the lactate dehydrogenase leakage and conserved the cellular morphology,

restored superoxide dismutase and catalase enzyme levels thereby preventing neuronal

damage.

CONCLUSION

Medicinal herbs as potential source of therapeutics aids has attained a significant role in

health care system all over the world for human beings not only in the diseased condition but

also as potential material for maintaining proper health. It is clear that the herbal industry can

make great strides in the world. With the increased use of herbal products, the future

worldwide labeling practice should adequately address quality aspects. Standardization of

methods and quality control data on safety and efficacy are required for understanding of the

use of herbal drugs. A major factor impeding the development of the medicinal plant based


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industries in developing countries has been the lack of information on the social and

economic benefits that could be derived from the industrial utilization of medicinal plants.

Further research is required to exploit the compounds responsible for the observed biological

activity. The management of neurodegenerative diseases remains a challenge in the modern

medicine because of their complicated pathogenesis. Protein misfolding and their

accumulation inside or outside of neurons is the key pathological feature in several

neurodegenerative diseases including Alzheimer's, Parkinson's Huntington's disease. Herbal

medicines are regarded as effective and promising sources of potential neuroprotective agents

because of their cognitive benefits and more significantly, their mechanisms of action with

respect to the fundamental pathophysiology of the diseases. Our review has acknowledged

several herbal medicines such as such as Acorus calamus, Bacopa monnieri Ginkgo biloba,

Melissa officinalis, Ocimum sanctum, with potential therapeutic effects for neurodegenerative

diseases. It is anticipated that the information provided through this review should help the

researcher to provide some evidence and conceptual detail of the benefit of a wide range of

herbs as neuroprotective agents.

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MEDICINAL PLANTS IN NEURODEGENERATIVE DISEASE -A REVIEW