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ANTIVIRAL ACTIVITIES OF MEDICINAL PLANTS B.Pharma Final Year
Eaten to counter poisoning, but must be eaten quickly
Agaricus subrufescens
Agaricus blazei
May enhance immune system and have anti-cancer properties (Reviewed by Hetland) ]
Allium sativum Garlic
Antibiotic (in vitro)/stops infectionNicole Johnston (April 2002). "Garlic: a natural antibiotic". Modern Drug Discovery
Cardiovascular health
Aloe ferox
Anethum graveolens Dill and Dill oil used to soothe the stomach after meals
Amorphophallus konjac
Konjac
Atopic dermatitis
high cholesterol
Arnica montana Arnica
Used for strains, sprains, and bruises. The roots contain derivatives of thymol,[14] which are used as fungicides and preservatives and may have some anti-inflammatory effect.
Aquilaria agollocha Eaglewood
Artemisia annua L. Sweet sagewort
Help to prevent the development of parasite resistance,it also has anti-malarial properties, and has anti-cancer properties
Artemisia absinthium L.
Wormwood Removal of internal parasites
Aristolochia rotunda Smearwort
Arum maculatum Lords and Ladies
Astragalus membranaceus
Astragalus
Cannabis Sativa
Cannabis, Cannabis sativa, Marijuana, Hashish
Pain relief, hunger stimulation, wasting caused by HIV/AIDS, Glaucoma, nausea, | anticarcinogenic through angiogenesis inhibition through various
ANTIVIRAL ACTIVITIES OF MEDICINAL PLANTS B.Pharma Final Year
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agents such as tetrahydrocannabinol, cannabidiol, hexahydrocannabinol, quinone, arachidonyl ethanolamide
Citrus aurantium ssp. bergamia
Bergamot orange Malaria
Crataegus spp. L. Hawthorn Nervous tension
Cydonia oblonga Quince
Cymbopogon flexuosus
Lemon grass
Cymbopogon schoenanthus
Fever grass
Digitalis lanata Digitalis, Balkan Foxglove Antiarrhythmic agent and inotrope
Echinacea purpurea
Purple coneflower, and other species of Echinacea
Reduce the severity and duration of symptoms associated with cold and flu.
Filipendula ulmaria (Spiraea ulmaria)
Meadowsweet
Fevers and inflammations. Pain relief. Ulcers. Bacteriostatic. Listed as therapeutical in 1652 by Nicholas Culpeper. In 1838, salicylic acid was isolated from the plant. The word Aspirin is derived from spirin, based on Meadowsweet's synonym name Spiraea ulmaria.
Pain relief. Morphine made from the refined and modified sap is used for pain control in terminal patients. Dried sap was used as a traditional medicine until the 19th century.
ANTIVIRAL ACTIVITIES OF MEDICINAL PLANTS B.Pharma Final Year
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Passiflora spp. Passion-flower Insomnia
Phytolacca spp. Pokeweed
Topical: acne
Internal: tonsilitis
Plantago spp. Plantain and Psyllium Astringent
Salvia stenophylla Blue Mountain Sage
Poppiocious seediouphylla
Poppy seeds Helps sleeping/relieves pain
Rosmarinus officinalis
Rosemary
Salix alba White willow
Ancient medicine, already described by Greek pharmacologist Dioscorides. Bark contains salicylic acid, which name is derived from Salix.
Symphytum officinale
Comfrey Stops infection
Salvia officinalis Sage Improves cognitive function in mild to moderate Alzheimer's disease.
Tanacetum parthenium (Chrysanthemum parthenium)
Feverfew Relieves Migranes, helps fevers and chills.
Taraxacum officinale
Dandelion Digestive
Tilia spp. Lime Blossom
Urtica dioica Stinging Nettle
Valeriana officinalis Valerian Sedative
Verbascum thapsus Mullein
boosts the Immune system, antispasmodic, diuretic, anodyne, and demulcent Used to treat coughs, (protracted) colds, hemoptysis, catarrh, dysentery, diarrhoea and as a general tonic (like ginseng) to boost the immune system
Zingiberis rhizoma Ginger can help ease nausea from chemotherapy
ANTIVIRAL ACTIVITIES OF MEDICINAL PLANTS B.Pharma Final Year
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There are hundreds of plants used all over the world, which are used in herbal medicine
as treatments for viral infections.
Here are some of the most accessible and reliable natural antiviral herbs:
Astragalus (astragalus membranaceus) : has been in the Chinese Materia Medica for
centuries and has shown to have immune boosting properties. This classic energy tonic
has a warming and toning effect. Although not used as a treatment for acute illnesses,
astragalus is believed to be very useful as an herbal remedy for treating viral infections,
including those that cause the common cold and flu.
Echinacea (eucalyptus globulus): has long been used as an antiviral remedy for colds
and flu. It appears to work by boosting production of interferon, the body’s own antiviral
fighter, as well as, stimulating infection-fighting white blood cells. Echinacea has three
compounds, which are chicoric acid, caffeic acid, and echinacin. These three compounds
have specific antiviral properties that can resist viruses.
Forsythia (Forsythia suspensa) and Honeysuckle (Lonicera japonica) are the top choice in
the Chinese Materia Medica for addressing heat toxins. Often used together, these
flowers are the main ingredient in a formula called Yin Qiao San for treating viruses
causing upper respiratory infections.
Garlic (allium sativum): Compounds that are rich in sulfur content are found in
abundance in garlic and are active against the virus responsible for flu. These sulfur-
based compounds have shown to be effective in clinical studies. A similar but less
effective antiviral action is also found in the common onion, which is a close relative of
the garlic plant.
Ginger (zingiber officinale): Phenolic compounds are responsible for relaxing the
muscles of the stomach, and explains ginger‘s effect in easing motion sickness. Fresh or
dried, the root has been shown to minimize vomiting. In addition, the phenolic
ingredients act within the stomach as a sedative and painkiller, which helps to reduce
over-activity of the gut. In stomach infections, the oil acts as an antiseptic and an anti-
ANTIVIRAL ACTIVITIES OF MEDICINAL PLANTS B.Pharma Final Year
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inflammatory. The gingerols alone are thought to be responsible for ginger‘s action as a
liver protective.
Goldenseal (hydrastis canadensis): Berberine is the active compound in goldenseal that
stimulates the immune system. douche of goldenseal is excellent for reducing yeast
infection. Berberine increases blood flow to the spleen and stimulate the activity of
macrophages, blood cells that are an important part of the immune system.
Licorice (glycyrrhiza glabra): also used for centuries and found in the Chinese Materia
Medica, this herb’s potent antiviral action works against a wide range of viral agents.
With eight active antiviral compounds, the most recognized being glycyrrhizin, these
compounds inhibit as well as block the viral penetration of the body’s cells and the
multiplication of genetic material from the viral particle.
Essential Oils with Antiviral Properties
Use these oils externally by blending a few drops into a base oil of vegetable, sunflower,
safflower or canola oils and massage into pulse points, chest, tops of feet and wrists. Do
not digest these oils internally. Tea tree can be added to a half a cup of warm water and
gargled then spit out for treating sore throats.
Eucalyptus (eucalyptus globulus): this oil has compounds which include quercitrin,
hyperoside, and tannic acid, which help eliminate viruses.
Juniper (juniperus): has an antiviral agent. Juniper contains a potent antiviral compound
called deoxypodophyllotoxi n. The herpes viruse, flu and many other types of viruses
seem to be inhibited by extracts from juniper .
Lemon Balm (melissa officinalis) : is a potent inhibitor on the herpes virus, among other
viruses that lead to infection.
Tea Tree Oil (melaleuca alternifolia) : used for everything from earache to athlete’s
foot, as well as gum inflammation and skin infections, this antiviral oil can be applied
directly to an infected area, three times daily. Tea tree can be added to a half a cup of
warm water and gargled then spit out for treating sore throats.
ANTIVIRAL ACTIVITIES OF MEDICINAL PLANTS B.Pharma Final Year
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� Some important antiviral activity of plants
Antiviral drugs are a class of medication used specifically for treating viral infections.
Like antibiotics, specific antivirals are used for specific viruses. They are relatively
harmless to the host, and therefore can be used to treat infections. They should be
distinguished from viricides, which actively deactivate virus particles outside the body.
Most of the antiviral now available are designed to help deal with HIV; herpes viruses,
best known for causing cold sores and genital herpes, but actually causing a wide range
of diseases; the hepatitis B and C viruses, which can cause liver cancer, and influenza A
and B viruses. Researchers are now working to extend the range of antivirals to other
families of pathogens.
Antiviral drugs work by inhibiting the virus before it enters the cell, stopping it from
reproducing, or, in some cases, preventing it from exiting the cell. However, like
antibiotics, viruses may evolve to resist the antiviral drug.
VIRUS: AN INTRODUCTION
Virus are obligate intracellular organism, contain DNA or RNA within a cylindrical or
spherical protein coat or capsid, which may be surrounded by a lipid bilayer (envelope).
Viruses are organisms that can be characterized as having two distinct phases in their life
cycle - an intracellular and an extracellular phase.
Intracellular phase is the replicative phase during which the virus multiplies in the
infected cell. There it borrows the metabolic machinery of the cell to direct the synthesis
of proteins coded by the viral genome. The structural and nonstructural virion
components are synthesized independently, and the structural proteins are assembled into
whole virions during the final stage of reproduction. When virions leave the cell, they are
particles of uniform size, shape and chemical composition that in some cases can
crystallize. This is the extracellular phase of the virus. The viral particles can initiate the
infectious process of new cells, and hence they constitute the infectious form of the virus.
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Virus life cycle
Viruses consist of a genome and sometimes a few enzymes stored in a capsule made of
protein (called a capsid), and sometimes covered with a lipid layer (sometimes called an
'envelope'). Viruses cannot reproduce on their own, and instead propagate by subjugating
a host cell to produce copies of themselves, thus producing the next generation.
Researchers working on such "rational drug design" strategies for developing antivirals
have tried to attack viruses at every stage of their life cycles. Some species of mushrooms
have been found to contain multiple antiviral chemicals with similar synergistic effects.[3]
Viral life cycles vary in their precise details depending on the species of virus, but they
all share a general pattern:
• Attachment to a host cell.
• Release of viral genes and possibly enzymes into the host cell.
• Replication of viral components using host-cell machinery.
• Assembly of viral components into complete viral particles.
• Release of viral particles to infect new host cells.
Limitations of vaccines
Vaccines bolster the body's immune system to better attack viruses in the "complete
particle" stage, outside of the organism's cells. They traditionally consist of an attenuated
(weakened or killed) version of the virus. These vaccines can, in rare cases, harm the host
by inadvertently infecting the host with a full-blown viral occupancy. Recently "subunit"
vaccines have been devised that consist strictly of protein targets from the pathogen.
They stimulate the immune system without doing serious harm to the host. In either case,
when the real pathogen attacks the subject, the immune system responds to it quickly and
blocks it.
Vaccines are very effective on stable viruses, but are of limited use in treating a patient
who has already been infected. They are also difficult to successfully deploy against
ANTIVIRAL ACTIVITIES OF MEDICINAL PLANTS B.Pharma Final Year
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rapidly mutating viruses, such as influenza (the vaccine for which is updated every year)
and HIV. Antiviral drugs are particularly useful in these cases.
Anti-viral targeting
The general idea behind modern antiviral drug design is to identify viral proteins, or parts
of proteins, that can be disabled. These "targets" should generally be as unlike any
proteins or parts of proteins in humans as possible, to reduce the likelihood of side
effects. The targets should also be common across many strains of a virus, or even among
different species of virus in the same family, so a single drug will have broad
effectiveness. For example, a researcher might target a critical enzyme synthesized by the
virus, but not the patient, that is common across strains, and see what can be done to
interfere with its operation.
The target proteins can be manufactured in the lab for testing with candidate treatments
by inserting the gene that synthesizes the target protein into bacteria or other kinds of
cells. The cells are then cultured for mass production of the protein, which can then be
exposed to various treatment candidates and evaluated with "rapid screening"
technologies.
Approaches by life cycle stage
Before cell entry
One anti-viral strategy is to interfere with the ability of a virus to infiltrate a target cell.
The virus must go through a sequence of steps to do this, beginning with binding to a
specific "receptor" molecule on the surface of the host cell and ending with the virus
"uncoating" inside the cell and releasing its contents. Viruses that have a lipid envelope
must also fuse their envelope with the target cell, or with a vesicle that transports them
into the cell, before they can uncoat.
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This stage of viral replication can be inhibited in two ways:
• Using agents which mimic the virus-associated protein (VAP) and bind to the
cellular receptors. This may include VAP anti-idiotypic antibodies, natural
ligands of the receptor and anti-receptor antibodies.
• Using agents which mimic the cellular receptor and bind to the VAP. This
includes anti-VAP antibodies, receptor anti-idiotypic antibodies, extraneous
receptor and synthetic receptor mimics.
This strategy of designing drugs can be very expensive, and since the process of
generating anti-idiotypic antibodies is partly trial and error, it can be a relatively slow
process until an adequate molecule is produced.
Entry inhibitor
A very early stage of viral infection is viral entry, when the virus attaches to and enters
the host cell. A number of "entry-inhibiting" or "entry-blocking" drugs are being
developed to fight HIV. HIV most heavily targets the immune system's white blood cells
known as "helper T cells", and identifies these target cells through T-cell surface
receptors designated "CD4" and "CCR5". Attempts to interfere with the binding of HIV
with the CD4 receptor have failed to stop HIV from infecting helper T cells, but research
continues on trying to interfere with the binding of HIV to the CCR5 receptor in hopes
that it will be more effective.
Uncoating inhibitor
Inhibitors of uncoating have also been investigated.Amantadine and rimantadine, have
been introduced to combat influenza. These agents act on penetration/uncoating.
Pleconaril works against rhinoviruses, which cause the common cold, by blocking a
pocket on the surface of the virus that controls the uncoating process. This pocket is
similar in most strains of rhinoviruses and enteroviruses, which can cause diarrhea,
meningitis, conjunctivitis, and encephalitis.
During viral synthesis
A second approach is to target the processes that synthesize virus components after a
virus invades a cell.
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Reverse transcription
One way of doing this is to develop nucleotide or nucleoside analogues that look like the
building blocks of RNA or DNA, but deactivate the enzymes that synthesize the RNA or
DNA once the analogue is incorporated. This approach is more commonly associated
with the inhibition of reverse transcriptase (RNA to DNA) than with "normal"
transcriptase (DNA to RNA).The first successful antiviral, acyclovir, is a nucleoside
analogue, and is effective against herpesvirus infections. The first antiviral drug to be
approved for treating HIV, zidovudine (AZT), is also a nucleoside analogue.
An improved knowledge of the action of reverse transcriptase has led to better nucleoside
analogues to treat HIV infections. One of these drugs, lamivudine, has been approved to
treat hepatitis B, which uses reverse transcriptase as part of its replication process.
Researchers have gone further and developed inhibitors that do not look like nucleosides,
but can still block reverse transcriptase.Another target being considered for HIV
antivirals include RNase H - which is a component of reverse transcriptase that splits the
synthesized DNA from the original viral RNA .
Integrase
Another target is integrase, which splices the synthesized DNA into the host cell genome.
Transcription
Once a virus genome becomes operational in a host cell, it then generates messenger
RNA (mRNA) molecules that direct the synthesis of viral proteins. Production of mRNA
is initiated by proteins known as transcription factors. Several antivirals are now being
designed to block attachment of transcription factors to viral DNA.
Translation / antisense
Genomics has not only helped find targets for many antivirals, it has provided the basis
for an entirely new type of drug, based on "antisense" molecules. These are segments of
DNA or RNA that are designed as complementary molecule to critical sections of viral
genomes, and the binding of these antisense segments to these target sections blocks the
operation of those genomes. A phosphorothioate antisense drug named fomivirsen has
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been introduced, used to treat opportunistic eye infections in AIDS patients caused by
cytomegalovirus, and other antisense antivirals are in development. An antisense
structural type that has proven especially valuable in research is morpholino antisense.
Morpholino oligos have been used to experimentally suppress many viral types:
• caliciviruses
• flaviviruses (including WNV)
• dengue
• HCV
• coronaviruses
Translation / ribozymes
Yet another antiviral technique inspired by genomics is a set of drugs based on
ribozymes, which are enzymes that will cut apart viral RNA or DNA at selected sites. In
their natural course, ribozymes are used as part of the viral manufacturing sequence, but
these synthetic ribozymes are designed to cut RNA and DNA at sites that will disable
them.
A ribozyme antiviral to deal with hepatitis C has been suggested, and ribozyme antivirals
are being developed to deal with HIV.[13] An interesting variation of this idea is the use of
genetically modified cells that can produce custom-tailored ribozymes. This is part of a
broader effort to create genetically modified cells that can be injected into a host to attack
pathogens by generating specialized proteins that block viral replication at various phases
of the viral life cycle.
Protease inhibitors
Some viruses include an enzyme known as a protease that cuts viral protein chains apart
so they can be assembled into their final configuration. HIV includes a protease, and so
considerable research has been performed to find "protease inhibitors" to attack HIV at
that phase of its life cycle.[14] Protease inhibitors became available in the 1990s and have
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proven effective, though they can have unusual side effects, for example causing fat to
build up in unusual places. Improved protease inhibitors are now in development.
Protease inhibitors have also been seen in nature. A protease inhibitor was isolated from
the Shiitake mushroom (Lentinus edodes).The presence of this may explain the Shiitake
mushrooms noted antiviral activity in vitro.
Assembly
Rifampicin acts at the assembly phase.
Release phase
The final stage in the life cycle of a virus is the release of completed viruses from the host
cell, and this step has also been targeted by antiviral drug developers. Two drugs named
zanamivir (Relenza) and oseltamivir (Tamiflu) that have been recently introduced to treat
influenza prevent the release of viral particles by blocking a molecule named
neuraminidase that is found on the surface of flu viruses, and also seems to be constant
across a wide range of flu strains.
Immune system stimulation
A second category of tactics for fighting viruses involves encouraging the body's immune
system to attack them, rather than attacking them directly. Some antivirals of this sort do
not focus on a specific pathogen, instead stimulating the immune system to attack a range
of pathogens.One of the best-known of this class of drugs are interferons, which inhibit
viral synthesis in infected cells.[19] One form of human interferon named "interferon
alpha" is well-established as part of the standard treatment for hepatitis B and C,[20] and
other interferons are also being investigated as treatments for various diseases.
A more specific approach is to synthesize antibodies, protein molecules that can bind to a
pathogen and mark it for attack by other elements of the immune system. Once
researchers identify a particular target on the pathogen, they can synthesize quantities of
identical "monoclonal" antibodies to link up that target. A monoclonal drug is now being
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sold to help fight respiratory syncytial virus in babie and antibodies purified from
infected individuals are also used as a treatment for hepatitis B.
AAAAidsidsidsids
The acquired immune deficiency syndromes (AIDS) is the state of profound immuno-
suppression produced by chronic infection with the human immune deficiency virus
(HIV). It is characterized by profound immunosuppression that leads to opportunistic
infections, secondary neoplasm and neurologic manifestations.
Plants Used in Treating HIV
While new drugs are constantly being produced and studied for the treatment of HIV, or
human immunodeficiency virus, the use of plants is not out of the question. Plants are
still being used in developing nations in the hopes of treating, and one day curing, HIV.
Herbs
1. Herbal medicinal remedies have been used for centuries to treat a variety of ailments in
various cultures. Aloe vera, St. John's Wort, echinacea and ginseng have been used to
boost the immune system. Ginkgo, garlic and astragalus also help revive a failing
immune system.
Licorice
2. Licorice, or deglycyrrhizinated licorice, has a soothing effect on the mouth and throat for
HIV and AIDS patients suffering from ulcers in these places.
Astragalus Root
3. A Chinese herb, the astragalus root has been used in the East to prevent and slow the
shortening of telomere in immune cell chromosomes. Since HIV attacks the body's
immune cells, the use of the root is now being turned toward this virus. Experts believe
ANTIVIRAL ACTIVITIES OF MEDICINAL PLANTS B.Pharma Final Year
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the root can be added successfully to anti-retroviral therapies for HIV-positive persons or
perhaps replace them entirely for a lower cost.
Cat's Claw
4. A woody Peruvian vine used by the Ashanica Indians has been proven to reduce the side
effects of AZT therapy for HIV and AIDS patients. Known as cat's claw, it stimulates the
immune system's response to the disease.
South African Plant
5. Known as Sutherlandia frutescens, the South Africa native plant is being used as
an immune and energy booster for sufferers of HIV and AIDS. It is also an
effective anti-depressant.
Materials and methods
Plant material Seventeen plants (Table 3.2) which are used to treat, HIV- infections in
immunocompromised patients were collected from different areas in Mozambique
Preparation of plant extracts
Dried powdered plant materials wer e extracted with acetone .Fifty grams of powdered
plant material was extracted with 500 ml of solvent over two days under reflux.
The extracts were then filtered and concentrated to dryness under reduced pressure
and the residues freshly dissolved in an ap propriate solvent on the day that the bioassay
was done.
HIV-1 Reverse tra nscriptase (RT) assay The effect of plant extracts on RT activity in vitro was evaluated with a non-
radioactive HIV-RT colorimetric ELISA kit (Roche, Germany). The assay was carried out
in triplicate. Adriamycin, an anticancer drug and also an inhibitor of viral reverse
ANTIVIRAL ACTIVITIES OF MEDICINAL PLANTS B.Pharma Final Year
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transcriptase (Goud etal ., 2003) was used as a positive control.In each test well,
2µl of diluted recombinant HIV-1 reverse transcriptase (4-6 n g), 20µl o f diluted
extract, and 20µl o freaction mixture was dispensed. The final concentration of each
extract in each well was 20 µg/ml. Since this part of the experiment was not
conducted at the University of Pretoria, but at Nelson Mandela Metropolitan
University; due to cost implications, only one concentration was selected. Negative
control wells contained 40µl of lysis buff er and 20µl of reaction mixture. The
concentration of positive drug control (Adriamycin) was 100µ g/ml. Positive control