ANTIOXIDANTS
in
AROMATIC & MEDICINAL PLANTS
ince time immemorialman has been using plant extracts to protect himself against several diseases and also to improve his health and life-style. No doubt, plants are serving several purposes whether health, nutrition, beauty or medicinal. With the development in techniques and recent researches, it has been proved that certain non-nutritive chemicals in plants such as
terpenoids and flavonoids which were earlier thought to be of no importance to human diet, possess antioxidant properties.
The plants are susceptible to damage caused by active oxygen and thus develop numerous antioxidant defense system resulting in formation of numerous potent antioxidants. Many aromatic, medicinal and spice plants contain compounds that possess confirmed strong antioxidative components. The essential oils derived from aromatic plants not only serve as fragrance and flavour agents but also as dietary antioxidant expected to prevent several diseases caused by free radicals.
The essential oils are the secondary metabolites of the aromatic plants which include
S
the fragrant material extracted from the root, bark, wood, seed, fruit, leaf or flower of a single plant. Essential oils are extracted from the plants by various methods such as distillation (steam distillation, hydro distillation or hydro-steam distillation), mechanical compression, expression or solvent extraction etc. due to their volatile nature. These oils are very potent containing the odour, taste, and medicinal properties of the plant in concentrated form. The therapeutic properties of essential oils are utilized in massage, inhalation, diffusers, fresheners etc. The recent researches have also proved that these can also be used as antioxidants in order to protect our body from various disastrous and chronic diseases, like cancer, arthritis, common cold cough, cataracts etc. which weaken the immune system of the body. This article aims to focus on aromatic and medicinal plant(s)/molecules used as antioxidants and their behaviour to prevent the different disorders on human health and life style.
Antioxidants
Till date as such no set definition of antioxidants exists. Scientists are still striving hard to find out the role of particular dietary supplements in body that have potent health benefits. Since, different antioxidant compounds found in diet considerably vary from one another, it is a difficult task to identify the role of a single compound. In simple words, "Antioxidants are a type of complex compounds found in our diet that act as a protective shield for our body against certain disastrous enemies (diseases) such as arterial and cardiac diseases, arthritis, cataracts and also premature ageing along with several chronic diseases. "
The above definition gives an idea about what actually an antioxidant is as still a lot of work has to be carried on getting exact information about antioxidants, their exact amount in one's diet and their function1. The recent researches on free radicals
promise a revolutionary improvement in health and life-style of humans. Types of antioxidants: - Basically these are classified into three categories-
1. Enzymatic and Non-enzymatic antioxidants: - They are found both in extra cellular as well as intracellular environment. These are tactically arranged within the cell in order to provide maximum protection against free radicals. Some important enzymatic and non-enzymatic physiological antioxidants are as follows-
S. No.
Antioxidant Location Function/property
a) Enzymatic antioxidant 1. Glutathione
peroxidase (GSH)
Mitochondria& Cytosol Removal of H2O2 &
Organic hydro-peroxide 2. Catalase (CAT) Mitochondria & Cytosol Removal of H2O2
b) Non-enzymatic antioxidant
1. Carotenoids Lipid soluble
antioxidants in membrane tissue
Removal of reactive oxygen species
2. Bilirubin Product of heme
metabolism in blood
Extracellular antioxidants,
3. Glutathione Non-protein thiol in cell Cellular oxidant defense 4. α-lipoic acid Endogenous thiol Serves as substitute for
Glutathione, recycling Vit-C
5. Vitamin-C Aqueous phase of cell Free scavenger, recycle Vit-E
6. Vitamin-E Cell Chain breaking
antioxidants 7. Uric Acid Product of Purine
metabolism
Scavenging of OH radical
2. Antioxidant derived from natural and dietary sources: - Plants develop several antioxidants that aid in antioxidant defense system, protecting plants against damage caused by active O2 formed due to exposure to ultraviolet radiation. Certain
seaweeds also function as antioxidants. Our daily diet contains vegetables, fruits, tea, wine, etc. which possess compounds rich in anti oxidative properties2.
a. Antioxidants from natural sources: - Secondary products of plants which are functioning as antioxidant are:-
i. Chlorophyll derivatives ii. Essential oils
iii. Carotenoids iv. Alkaloids v. Phytosterols
vii. Polyphenolics - tannins, proanthocynidine
viii. Nitrogen containing compounds- alkaloids, indoles.
b. Dietary antioxidants: - These reduce the free radical formation as well as oxidative stress & reduce the possibility of cardiovascular diseases4. Several
compounds such as phenolic diterpenoids- camosol, rosmanol, camosoic acid, etc. obtained from several aromatic plants possess strong antioxidant properties.
3. Antioxidants based on defense mechanism:- These are of four types:
a. Preventive antioxidants - These suppress the free radical formation. ex. enzymes such as peroxidase, catalase, lactoferrin, carotenoids, etc5.
b. Radical scavenging antioxidants - These suppress the chain initiation reaction. ex Vitamin-C & Carotenoids.
b.Repair and de novo antioxidant- It comprise of proteolitic enzymes and repair enzymes of DNA and genetic materials.
d. Enzyme inhibitor antioxidants- These induce production and reaction of free radicals and the transport of appropriate antioxidants to appropriate active site. Functions of Antioxidants:-
i. Antioxidants such as Vitamin-C & E boost our immune system. ii. Certain phytochemicals have beneficial effect on heart diseases.
iii. Antioxidants lower the level of Low-density lipoprotein (LDL) cholesterol, thus preventing plaque deposition in the blood vessels.
iv. It is beneficial in cancer prevention.
v. Antioxidants neutralize substances that can damage the genetic material by oxidation.
Compounds that function as Antioxidants:- Vitamins
Vitamin C - It prevents free radical damage due to its property of donating free radicals. It is beneficial in boosting immune system. The main source of Vitamin-C is carrots, peaches, sweet potatoes, oranges, broccolis, etc7.
Vitamin E - Both plants and animals serve as a source of vitamin E. It has been found beneficial against certain types of cancer & cardiac problems. It is known as 'scavenger of free radicals’. Vitamin E is mainly present in nuts, whole cereal grains, almonds, vegetable oils etc.
biflavonoids, phenols, phytosterols, etc. that possess antioxidative properties.
Carotenoids - These are a group of antioxidant nutrients present in many fruits and
vegetables and are found effective if taken with dark coloured fruits such as carrots, tomatoes, beets, etc. These are further composed of α- carotene, β- carotene, Cryptoxanthin, Lycopene, Lutein & Zeaxanthin. They are present in red, dark orange & yellow fruits such as carrots, peaches, broccoli, pumpkins, sweet potatoes etc
Flavonoids - Plants contain flavonoids like quercetin, kaempferol which scavenge
free radicals and combat pathological disorders generated by phytochemicals’ Reactive Oxygen Species (ROS).
Phenols - Prevent oxidative damage of tissues from ROS of DNA, RNA, enzymes,
proteins and has anti-inflammatory properties.
Minerals - Selenium is an essential component of several enzymes that prevent free radical formation & their removal from blood stream. It occurs in grains, low-fat dairy products, poultry, organ meat, seafood etc.
Behaviour of Antioxidants:-
The free radicals play very important role in human health and beneficial in combating against several diseases. Before we understand the working, it is necessary to have a brief idea about free radicals. During a chemical reaction (oxidation), one reactant loses an electron and is called oxidant or free radical8, while
the other gains an electron. In living organisms oxygen in unstable form is the most common free radical. This is called Reactive Oxygen Species (ROS)9 and is
generated during various metabolic activities. Contaminants in the environment as well as normal metabolism of a cell, can change molecule into a free radical. The examples of ROS. are OH , O2 , H2O2, O3, HOCI, RO2, RO.
Any molecule can become a free radical by either losing or gaining an electron. Once initiated these free radicals get involved in chain reaction with stable types. The compounds thus formed have longer stability and in body and increase the potential for cellular damage. Free radicals damage the cell at the site of their operation causing serious disorders. Plaque may accumulate in arteries on oxidation. LDL Cholesterol functions as free radical and damages the free artery lining. It hampers the blood circulation which may lead to heart attack.
Stages of free radicals- i) Initiation ii) Propagation iii) Termination
The initiation and propagation stages have already been discussed earlier. However termination or neutralization of free radicals is achieved by antioxidants or enzymatic mechanism10. It is necessary to balance the fee radical & antioxidant activity.
Effects of Excess of Free Radicals:
i. Free radicals damage DNA, RNA, proteins, enzymes ii. Lead to the formation of tumours & cause cancers.
iii. Cardiovascular Diseases iv. Nervous disorders
v. Premature ageing.
vi. Parkinson's & Alzheimer's Diseases vii. Rheumatic & Pulmonary Disorders
Requirement of antioxidants in the body:-
A number of processes are taking place in our body like breathing, breaking up of protein in the body or exposure of body to air pollution or UV radiation leads to the formation of free radicals that aid in the process of oxidation which further leads to several health problems.
If the body is healthy it is capable enough to break down these free radicals before they become harmful. In case, the formation of the free radicals exceeds in the body, it can damage the cells and tissues. This damage can be counteracted by antioxidants which prevent the free radical formation and if the formation occurs it helps in their removal from blood stream. Thus antioxidants play potentially beneficial role in the risk reduction and treatment of diseases.
ESSENTIAL OILS AS ANTIOXIDANTS
Essential oils
As discussed earlier these are a class of volatile oils that can be obtained by steam distillation .. These oils may be extracted from plants , fruits, flowers, barks, roots and
seeds where each possesses its unique characteristics Advantages of using Essential oils as antioxidants-
1. Due to their small molecular size, they can easily penetrate the skin tissue.
2. As essential oils are lipid soluble they are capable of penetrating the membranes easily even in conditions when oxygen deficiency leads to hardening of membranes. Studies reveal that essential oils serve as powerful antioxidants that produce adverse environment for damaging free radicals thus prevent mutations and oxidants in cells. Thus, they function as scavengers for free radicals.
MAJOR AROMATIC AND MEDICINAL PLANTS AND THEIR ANTIOXIDATIVE PROPERTIES
1. Ashwagandha (Withania somnifera)- Leaves, roots and berries of the plant possess anti oxidative properties. It prevents premature ageing and arthritis, enhances psychomotor co-ordination & immune system. Berries are blood tonifier that improves circulation & absorption of nutrients by cells.Leaves are used for treatment of tumors. Withaferin A, Viscosalactone B (12) inhibits the tumor formation. 2.Basil-linalool rich (Ocimum sanctum/canum)- The leaves of the plants are used to prevent free radical formation and has been found useful in treating arthritis, muscular pains & rheumatism. The main constituents responsible for anti oxidative property of basil are Ascorbic acid, β-carotene, β -sitosterol, eugenol, palmitic acid and tannin.
3.Black Pepper (Piper nigrum) - The fruit of the plant is used in the treatment of arthritis, and effective against neuralgia, poor circulation, poor muscle tone, sprains and stiffness. Ascorbic acid, β -carotene, Lauric acid, Myristic acid, Palmitic acid, Piperine is the main constituents responsible for its antioxidative behaviour.
4.Burdock (Aretium lappalo)- The roots of the plant possess antioxidative properties and provide protection against cancer by controlling cell mutation. It possesses antibacterial and antifungal properties, purifies blood and supports immune system. Inulin and tannic acid are the constituents present in burdock that possess anti oxidative properties.
5.Barbed Skullcap (Scutellaria barbata)- The tea made from this herb is fruitful in treating liver, lung & rectal cancer. It has also been found potent in reducing tumor growth. Gallic acid in scutellaria is anticancerous in function.
6.Carrot (Daucus carota)- The β -carotene found in the carrot functions as antioxidant. It prevents accumulation of toxins and is effective in treatment of arthritis,
edema & rheumatism. Alanine, α-tocopherol, ascorbic acid, camphene, eugenol, γ-terpinene, histidine are the main constituents in carrot that possess antioxidant properties.
7.Coleus (Coleus ferscoli) – Commonly called as Paterchur the roots of the plant are used for fat lowering and prevent synthesis of high cholesterol in body. Ferscolin is the main component in the tea that has antioxidative property.
8.Clary Sage (Salvia sclarea)- The plant prevents free radical formation and is effective in treatment against arthritis and rheumatism. γ-terpinene, linalyl acetate, myrcene, palmitic acid androsemarinic acid are the main antioxidative components in the plant
9.Clove bud (Eugenia caryophyllata)- The inflorescence of clove is effective against treatment of arthritis, rheumatism and sprains. Acetyl-eugenol, ascorbic acid, β-carotene, β-sitosterol, caryophyllene-oxide, eugenol and isoeugenol are the main constituents in clove that possess antioxidative property.
10. Garlic (Allium sativum)- The leaves and bulb protects against free radical formation, reduce blood clotting & cholesterol level. Best when used with natural antioxidant and vitamins. Alanine, α-tocopherol, ascorbic acid, camphene, eugenol, γ-terpinene and histidine are the important anti oxidative constituents present in garlic.
11. Ginger (Zingiber officinalis)- The active compound of ginger is [6]-gingerol which is responsible for ginger flavour and has been found to inhibit human cancer growth. 6-Gingerol, alanine, ascorbic acid, histidine, lauric acid, Methionine, Myristic acid, palmitic acid and tryptophan are the main antioxidative constituents in the ginger plant.
12. Green Tea (Camalia bensgalensis)- Tea extract, decreases cellular tissues damage thus prevent ageing. It also supports immune system. The Green Tea extract Epigallocatechin-3- gallate (EGCG) is thought to have anticancerous properties and reduces liver cancer. EGCG and polyphenols are the main antioxidative constituents of green tea.
13. Gingko (Ginkgo biloba)-The extract of the plant improves blood circulation, prevents free radical damage and prevents premature ageing. EGB 761 and ginkgogolide are the chief antioxidative constituents.
14. Grape (Vitis vinifera)- The OPC (Oligomeric proanthocynidine) is a powerful component present in grape seed. It acts as super antioxidant, protecting cells against free radical formation. It reduces LDL cholesterol and the risk of cardiovascular tissue. It enhances the ability of collagen to repair itself preventing degeneration. It also increases the strength & elasticity of blood vessels, protecting against rupture, leakage & degeneration. OPC, reduces High Blood Pressure by
inhibiting the activity of Angiotensin converting enzyme (ACE). It improves the strength of capillaries & blood vessels. In comparison to Vitamin C, OPC is more powerful antioxidant. It has sparing effect on Vitamin C by blocking the action of ascorbate oxydase enzyme that destroys Vitamin C. Alanine, α-tocopherol, ascorbic acid, β-carotene, β-Sitosterol, histidine, methionine, OPC, palmitic acid and selenium are the main anti oxidative constituents found in grape.
15. GugguI (Commifera mukul)- The gum yielded from the plant is used for treatment of arthritis and lowering blood pressure.
16. Lemongrass (Cymbopogon flexuosus)- It is found to have a refreshing effect on the body and possesses immune modulatory properties. β-Sitosterol, Myrcene and Selenium in lemongrass are responsible for its antioxidative behaviour.
17. Myrrh (Commiphora myrrha)- The resin exudates and sap content is found to be effective against arthritis. β-Sitosterol, campestrol and eugenol in myrrh have antioxidative effect.
18. Nutmeg (Myristica fragrans)-The fruit of nutmeg beneficial against arthritis, muscular aches & pains, rheumatism, improves circulation. It protects nervous system and provides immunity against bactericidal infection. Camphene, eugenol, γ-terpinene, isoeugenol, lauric acid, Myrcene, palmitic acid and terpene-4-ol in nutmeg possess antioxidative properties.
19. Olive (Olea europaea)- The leaf extract of olive contains α-tocopherol, apigenin, β-carotene, γ-tocopherol, kaempferol and Luteolin which is immune modulatory, maintains sugar & cholesterol level in the body.
20. Oregano (Origanum vulgare)- Thymol & rosamarinic acid in oregano prevents oxygen based damage to the cells in the body. It is found to be 42 times more antioxidant activity than apples, 30 times more antioxidant activity than potatoes, 4 times more antioxidant activity than blueberries, 12 times more antioxidant property than oranges and acts as immune booster. Thymol and rosemarinic acid are the antioxidative constituents in oregano.
21. Peppermint (Mentha piperita)- Limonene and menthol in the leaves of the plant have been found anticancerous.
22.Periwinkle (Catharanthus roseus)- Alkaloids (Vincristin & Vinblastin) of the plant are anticancerous.
23. Rosemary (Rosemarinus olficinalis.)- The oleoresin extract of the plant scavenges superoxide radicals, inhibit lipid oxidation in food system. It contains oil soluble antioxidants. Carsonic acid, rosemaric acid, β-Sitosterol, caryophyllene oxide, eugenol and iso-eugenol in the plant have been found antioxidative in nature.
24. Sandalwood (Santalum album)- Alanine, β-Sitosterol, eugenol, palmitic acid, phenol are the constituents found in the plant that have antioxidative effect. Mainly
the wood or the bark of the plant is used. It prevents premature ageing and rejuvenates the skin. Alanine, β-Sitosterol, eugenol, palmitic acid and phenols are the antioxidative constituents in sandalwood.
25. Thyme Serpolet (Thymus vulgaris)- The entire plant possesses antioxidative properties. It enhances blood circulation. 4-terpenol, alanine, β-carotene, caffeic acid, camphene, carvacrol, γ-terpinene, lycopene, myrcene and palmitic acid are the active antioxidative constituents in thyme.
26. Turmeric (Curcuma longa)- Curcumin found in the turmeric prevents free radical formation, premature ageing and possesses anticancerous properties.
CHEMICAL CONSTITUENTS IN AROMATIC AND MEDICINAL PLANTS WITH ANTIOXIDATIVE PROPERTIES AT A GLANCE
Plant Common name
Botanical name
Part used Chemical Constituents Possible antioxidative effects Ashwagand ha Withania somnifera Berries, Leaves, Roots WithaferinA, Viscosalactione B(12) Psychomotor co-ordinator, immune booster, anticancerous, prevents premature ageing, blood tonifier Basil Ocimum sanctum/can um Leaves,see ds Ascorbic acid, β- carotene, β-sitosterol, eugenol, Palmitic acid, tannin
Free radical scavenger, used against arthritis, muscular pains, rheumatism Black pepper
Piper nigrum Fruit Ascorbic acid, β-carotene, Lauric acid, Myristic acid, Palmitic acid, Piperine In arthritis, neuralgia, poor circulation Burdock Aretium lappalo
Root Inulin, tannic acid Treat painful joints,antibacteri al &antifungal, immune modulatory Barbed Skullcap Scutellaria barbata Leaves,Tea extract
Gallic acid Anticancerous Carrot Daucus carrota Leaves,see d, root Alanine, α-tocopherol, ascorbic acid, camphene, eugenol, γ -terpinene, histidine Antitoxin, used against arthritis, edema, rheumatism
Coleus Coleus ferscoli
Roots Ferscolin Lowering LDL
cholestrol Clary sage Salvia
sclarea Entire plant, seed γ-terpinene, linalyl acetate, myrcene, Palmitic acid, rosemarinic acid Free radical scavenger, treats arthritis, rheumatism Clove bud Eugenia
caryophylla Inflorescenc e Acetyl-eugenol, ascorbic acid, β -carotene, β- sitosterol, caryophyllene-oxide,eugenol,isoeug enol Treat arthritis, rheumatism, sprains
Garlic Allium sativum Leaves, bulb Alanine, ascorbic acid, β-sitosterol, caffeic acid, kaemferol, methionine Anticancerous, lower blood pressure Ginger Zingiber officinalis Leaves,rhiz ome 6-Gingerol, alanine,ascorbic acid, histidine, lauric acid, methionine, myristic acid, Palmitic acid, tryptophan
Anti-cancerous
Green Tea Camatia
bergalensis Leaves-Tea extract Epigallocathecin-3-gallate,epigallocathe cin, polyphenols Effective in acute pancreatitis, anticancerous, lower LDL cholesterol, reduces cardiovascular disease Ginkgo Ginkgo biloba Plant extract EGB 761, ginkgogolide Free radical scavenger, prevents premature ageing Grape Vitis vinifera Fruit, seed Alanine,α-tocopherol,
ascorbic acid, β -carotene, β -sitosterol, histidine, OPC, methionine, Palmitic acid, selenium Reduce LDL cholesterol & High Blood Pressure, strengthens blood vessel & capillaries, Immune modulatory
Lime Citrus
aurantifolia
Fruit Alanine, α -pinene, ascorbic acid, β -Sitosterol, caffeic acid, eugenol, linalyl acetate, Palmitic acid, tannin Prevents oxidation of fats & cholesterol, immune modulatory Lemongrass Cymbopogon citratus Leaves β-sitosterol, Myrcene, Selenium Refreshing & immune modulatory Myrrh Commiphora myrrha Resin exudates, sap β-Sitosterol, campestrol, eugenol Effective against arthritis Nutmeg Myristica fragrance
Seed, leaf Camphene, eugenol,
γ-terpinene,isoeugenol
Protects nervous system,used
, lauric acid, Myrcene, Palmitic acid, terpene-4-ol against Arthritis,rheumat ism, poor circulation
oregano Origanum vulgare
Leaves Thymol, rosemarinic acid Prevent ROS formation, immune booster Olive Olea europaea
Leaf extract α -tocopherol, apigenin, β -carotene, γ -tocopherol, kaempferol, Luteolin Immune modulatory, maintain sugar & cholesterol level Peppermint Mentha piperata
Leaves Menthol,limonene Anticancerous Periwinkle Catharanthu
s roseus
Entire plant Vincristine,binblastin e anticancerous Rosemary Rosemarionu s officinalis L. Leaf extract, Oleoresin extract Carsonic acid,rosemaric acid, β -sitosterol ,caryophyllene oxide,eugenol,isoeug enol Scavenges free radical,inhibit lipid oxidation Sandalwood Santalum album
Fruit, wood Alanine, eugenol,
β -sitosterol, Palmitic acid, phenol
Refreshing, prevents premature ageing Thyme Thymus vulgaris
Plant, leaf 4-terpenol,alanine, β -carotene, caffeic acid, camphene, γ -terpinene, carvacrol, lycopene, myrcene, Palmitic acid Enhances blood circulation, effective against sprains, muscular pains, arthritis Turmeric Curcuma domestica
Rhizome Curcumin Prevents free
radical damage, premature ageing,
This review throws light on the different medicinal and aromatic plants which do have the potential to be used as antioxidants. The plants can be used as such in the form of extracts, essential oils absolute, oleoresins or isolates. These compounds can find use in food products as well as in herbal cosmetics where we need to store the product for fairly long period before reaching in the hands of customer. There still exists a potential to search even more medicinal and aromatic plants which do have antioxidant properties or even much better when two or more of them are used together.
At present there does exist a dire necessity to conduct work on such issues where the potential of utilizing these plants could be harnessed. Undoubtedly, such thing will find a good scope in today’s world where back to nature movement is advancing.
REFERENCES:
1. Mayo Clinic Health Letter, 1995,11, 1-2.
2. Institute of Food Research, Annual Report, 1997. 3. Larson, R., Phytochemistry, 1988, 27(40), 969-978.
4. Bray, T.M., Society for Experimental Biology and Medicine, 1999, 195. 5. Parmer Lane, GNC News, 1995, 1.
6. Good, David, ed., The American Journal of Medicine, 1994, (3a-5s)-(3a-12s). 7. Burne, etal, eds., New York Academy of Sciences, New York, 1987, 498,
153-160.
8. Halliwell, B., Free Radical. Res., 1999, 31, 261-272. 9. Freiz, Balz., American Journal of Medicine, 1994, 97, 58. 10. Halliwell, Barry, The Lancet, 1994, 721-724.
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Jyotsna Mishra, R.K. Srivastava, S.V. Shukla and C.S. Raghav Fragrance and Flavour Development Centre, Kannauj125/K/64,
Govind Nagar, Kanpur-208006 Mob.- 9935999497, 9415334050
