1.
Introduction
Phytomedicines, also known as plant-derived drugs or herbal medicines, have been used worldwide since
ancient times for disease prevention and treatment because of their vast array of biological activities [1].
These medicines are derived from various plant parts, including leaves, bark, roots, and extracts, which
contain pharmacologically active compounds and secondary metabolites [2]. Phytomedicines are widely
used in different medicinal systems such as Ayurveda, Unani, Siddha, and Homeopathy [3]. Interestingly,
while phytomedicines are often perceived as safe, this is not always the case. There have been reports of
toxicities associated with certain plants, plant products, and herbal medicines [4]. Additionally, excessive
harvesting and habitat destruction have put many medicinal plants at risk, necessitating conservation efforts
to ensure sustainable utilization[5] Phytomedicines play a significant role in global healthcare, with 60-80%
of Asian and African populations using them for therapeutic purposes [6]. Their popularity is growing due to
their potential benefits, including fewer side effects and lower costs compared to synthetic counterparts .
[7].However, challenges remain, such as standardization, regulation, and conservation of medicinal plants.
Efforts are being made to establish harmonized regulations for herbal medicines globally to ensure safety,
quality, and efficacy[8]
In conclusion, phytomedicines offer outstanding contributions to modern therapeutics, providing efficacy for
primary health care due to their safety and fewer side effects. They are in great demand in the developed
world for treating infectious diseases and age-related disorders. The integration of phytomedicine into health
systems should be developed to bring harmony between traditional and modern systems of health care[9].
PHYTOCHEMICALS: BIOLOGICAL BACKGROUND
All plants produce chemical compounds as part of their normal metabolic activities. These include
primary metabolites, such as sugars and fats, found in all plants, and secondary metabolites found in
a smaller range of plants, some useful ones found only in a particular genus or species. It is the
secondary metabolites and pigments that can have therapeutic actions in humans and which can be
refined to produce drugs. These plant based drugs are efficient to work as phytomedicines in the
human body.
Plants up regulate and down regulate their biochemical paths in response to the local mix of
herbivores, pollinators and microorganisms (Baldwin, 2002). The chemical profile of a single plant
may vary over time as it reacts to changing conditions. Plants synthesize a bewildering variety of
phytochemicals but most are derivatives of a few biochemical motifs. Some of the phytochemicals
that can be useful as plant based drugs are discussed.
Alkaloids
Alkaloids contain a ring with nitrogen. Many alkaloids have dramatic effects on the central nervous
system.
Caffeine is an alkaloid that provides a mild lift but the alkaloids in Datura cause severe intoxication and
even death. Some of the alkaloids are hyoscyamine (Datura stramonium), atropine (present in Atropa
belladonna, Deadly nightshade), cocaine (present in Erythroxylon coca, the Coca plant), codeine and
morphine (present in Papaver somniferum, the opium poppy), tetrodotoxin (a microbial product in Fugu
and some salamanders), vincristine and vinblastine (mitotic inhibitors found in the Rosy Periwinkle)
Phenols
Phenols are a class of chemical compounds consisting of a hydroxyl group (-OH) bonded directly to
an aromatic
hydrocarbon group. The simplest of the class is phenol (C6H5OH). The anthocyanins that give grapes
their purple color, the isoflavones, the phytoestrogens from soy and the tannins that give tea its
astringency are phenolics
Terpenoids
Terpenoids are built up from terpene building blocks. Each terpene consists of two paired isoprenes.
The names monoterpenes, sesquiterpenes, diterpenes and tri- terpenes are based on the number of
isoprene units. The fragrance of rose and lavender is due to monoterpenes. The carotenoids produce
the reds, yellows and oranges of pumpkin, corn and tomatoes. Some of the terpenoids are
Azadirachtin, (Neem tree), Artemisinin (Artemisia annua Chinese wormwood), tetrahydrocannabinol
(Cannabis sativa), Steroids (Terpenes with a particular ring structure), Saponins
Glycosides
Glycosides consist of a glucose moiety attached to an aglycone. Glycosides are characterized by the
glycone, by the type of glycosidic bond, and by the aglycone. Some of the glycosides, by the type of
aglycone are alcoholic glycosides, anthraquinone glycosides, coumarin glycosides, cyanogenic
glycosides, flavonoid glycosides, phenolic glycosides (simple), saponins, steroidal glycosides or cardiac
glycosides, steviol glycosides and thioglycosides
Figure 1. Structure of phytochemicals. (a) Vinblastin, a chemotherapeutic alkaloid (b)
phenol, a carbolic acid (c) Artemisinin, a compound used in combination of others against
malaria (d) Salicin, a glycoside related to Aspirin.
Common Phytomedicines and Their Uses
Phytomedicines, derived from various parts of plants, have been used for centuries to treat a wide range of
health conditions. Below are some of the most commonly used phytomedicines and their applications:
1. Ginkgo biloba
Source: Leaves of the Ginkgo tree.
Uses: Primarily used to enhance cognitive function and memory. It is also used to treat symptoms of
dementia and Alzheimer’s disease. Ginkgo biloba is believed to improve blood circulation,
particularly to the brain, and has antioxidant properties that protect cells from damage.
2. St. John’s Wort (Hypericum perforatum)
Source: Flowers of the St. John’s Wort plant.
Uses: Commonly used to treat mild to moderate depression. It works by increasing levels of
serotonin, dopamine, and norepinephrine in the brain, which helps improve mood. Additionally, it is
used for anxiety, sleep disorders, and wound healing.
3. Echinacea
Source: Roots and aerial parts of the Echinacea plant.
Uses: Widely used to boost the immune system and reduce the duration and severity of colds and
respiratory infections. Echinacea is believed to stimulate the activity of white blood cells, enhancing
the body’s natural defense mechanisms.
4. Turmeric (Curcuma longa)
Source: Rhizomes of the turmeric plant.
Uses: Known for its anti-inflammatory and antioxidant properties, turmeric is used to treat conditions
such as arthritis, digestive disorders, and skin diseases. The active compound, curcumin, is also
being studied for its potential role in preventing cancer and Alzheimer’s disease.
5. Garlic (Allium sativum)
Source: Bulbs of the garlic plant.
Uses: Used for its cardiovascular benefits, garlic helps lower blood pressure and cholesterol levels. It
also has antimicrobial properties and is used to prevent and treat infections.
6. Ginseng (Panax ginseng)
Source: Roots of the ginseng plant.
Uses: Known for its adaptogenic properties, ginseng is used to improve physical and mental
performance, reduce stress, and boost the immune system. It is also used to manage diabetes and
enhance overall vitality.
7. Peppermint (Mentha piperita)
Source: Leaves of the peppermint plant.
Uses: Commonly used to treat digestive issues such as irritable bowel syndrome (IBS), nausea, and
indigestion. Peppermint oil is also used for its analgesic properties to relieve headaches and muscle
pain.
8. Aloe Vera
Source: Leaves of the Aloe Vera plant.
Uses: Widely used for its soothing and healing properties on the skin. Aloe Vera is used to treat
burns, wounds, and skin irritations. It is also used internally for its laxative effects and to support
digestive health.
9. Milk Thistle (Silybum marianum)
Source: Seeds of the milk thistle plant.
Uses: Primarily used to support liver health and treat liver conditions such as cirrhosis and hepatitis.
The active compound, silymarin, has antioxidant and anti-inflammatory properties that protect liver
cells from damage.
10. Chamomile (Matricaria chamomilla)
Source: Flowers of the chamomile plant.
Uses: Known for its calming effects, chamomile is used to treat anxiety, insomnia, and digestive
issues. It is also used topically to treat skin conditions and promote wound healing.
11. Ashwagandha (Withania somnifera)
Source: Roots and berries of the Ashwagandha plant.
Uses: Known for its adaptogenic properties, Ashwagandha is used to reduce stress, improve energy
levels, and enhance overall well-being. It is also used to support cognitive function and manage
conditions like arthritis and insomnia.
12. Lavender (Lavandula angustifolia)
Source: Flowers of the lavender plant.
Uses: Widely used for its calming and relaxing effects, lavender is used to treat anxiety, insomnia,
and headaches. It is also used in aromatherapy and as a topical treatment for skin irritations and
burns.
13. Ginger (Zingiber officinale)
Source: Rhizomes of the ginger plant.
Uses: Known for its anti-inflammatory and digestive properties, ginger is used to treat nausea,
motion sickness, and digestive issues. It is also used to reduce inflammation and pain associated with
conditions like osteoarthritis.
14. Valerian (Valeriana officinalis)
Source: Roots of the valerian plant.
Uses: Commonly used to treat insomnia and anxiety, valerian is known for its sedative effects. It is
also used to relieve muscle pain and menstrual cramps.
15. Saw Palmetto (Serenoa repens)
Source: Berries of the saw palmetto plant.
Uses: Primarily used to support prostate health and treat symptoms of benign prostatic hyperplasia
(BPH). It is also used to improve urinary function and reduce inflammation
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4. Research and Clinical Trials
5. Regulation and Quality Control
6. Challenges and Controversies
7. Future Prospects
8. Conclusion
