PHYTOCHEMICAL CONSTITUENTS AND ANTIOXIDANT ACTIVITIES OF THE CHLOROFORM EXTRACT OF OCIMUM GRATISSIMUM PLANT

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✎: PHYTOCHEMICAL CONSTITUENTS AND ANTIOXIDANT ACTIVITIES OF THE CHLOROFORM EXTRACT OF OCIMUM GRATISSIMUM PLANT

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Keywords: PHYTOCHEMICAL CONSTITUENTS AND ANTIOXIDANT ACTIVITIES OF THE CHLOROFORM EXTRACT OF OCIMUM GRATISSIMUM PLANT

 

RESEARCH BODY

ABSTRACT

Since ages, many plants have been used for preservative and medicinal purposes due to the presence of secondary metabolites referred as Phytochemicals. Phytochemicals are biologically active plant compounds having disease hampering capabilities and preservative action. The genus Ocimumcontains more than 200 species of herbs and shrubs which have been shown to have medicinal properties and also are used as a culinary herb, preservative and flavoring agents. In this study chloroform extracts from the leaves of Ocimumgratissimum was investigated for their phytochemical constituent (both quantitative and qualitative) and antioxidant activity. GCMS analysis was carried out to ascertain the specific amount and specific active component present in the leaf sample. The extract was screened for the presence of phenols, alkaloids, terpenoids, flavonoids, tannins, and Saponins. The test results were positive for all the phytochemicals,saponin and phytosterols which were absent qualitatively. The antioxidant activity was measured by the ferric reducing power assay, estimation of total flavonoids, saponins, tannins and phenols. The GC-MS analysis of the leaf sample suggested the presence ofthymol, alpha-carophyllene, phenol etc. The present investigation suggests that the phytochemical contents and antioxidant properties can be further studied for its application in health and in food industries. In addition, this plant can be used as a source of novel drugs for the treatment of infectious diseases caused by pathogenic microorganisms.

INTRODUCTION

Herbal medicines tend to look primitive and unscientific when compared to synthetic (conventional) drugs, which are thought to be more reliable than those made from plants. Herbal medicine is still the mainstay of about 75-80% of the world population, mainly in the developing countries for primary health care (Kamboj, V. P, 2000). This is primarily because of the general belief that herbal drugs are without any side effects, besides being cheap and locally available. The use of plants for healing purposes predates human history and forms the origin of much modern medicine. Many synthetic drugs originated from plant sources. A century ago, most of the few effective drugs were plant-based. Examples include: Aspirin (which is a chemical copy of the analgesic chemical in the bark of willow trees), digoxin (from fox glove), guanine (from the bark of various cinchona tree species which was used in the treatment of malaria) and morphine (from the opium poppy) (Vicker A. et al, 1999).

It’s been seen that a lot of plants had played effective roles in the production of drugs hence; we now look at the perennial plant, Ocimum gratissimum (scent leaf) which is widely distributed in the tropics of Africa and Asia. It belongs to the family labiatae and it is the most abundant of the genus Ocimum. It is called by various names in different parts of the world. In India it is known by its several vernacular names Vriddhutulsi (Sanskrit), Ram tulsi (Hindi) and Nimma tulasi (Kannada). In the southern part of Nigeria, the plant is called “effinrin-nla” by the Yoruba speaking tribe. It is called “Ahuji” by the Igbos, while in the Northern part of Nigeria, the Hausas call it “Daidoya” (Effraim KD et al, 2003). It is a perennial plant that is woody at the base. It has an average height of 1-3m high. The leaves are broad and narrowly ovate, usually 5-13cm long and 3-9cm wide. It is a scented shrub with lime-green fuzzy leaves (Wagner et al. 1999).

PLATE 1: WHOLE PLANT OF O. GRATISSIMUM (Effraim et al, 1999)

Many species of the genus Ocimum namely: Ocimum americanum, Ocimum basilicum, Ocimum canum, Ocimum gratissimum, Ocimum sanctum and Ocimum suave have been reputed for various medicinal uses. The chemical constituents of the plant have healing power and medicinal properties. The chemical components could be extracted using aqueous (water) or ethanonic methods and the leaves could be dried and powdered. The plant extract contains flavonoids, saponins, terpenes, cyanogenic glycosides, thymol, and alkaloids as its major phytochemical constituents (Effraim et al, 1999). Ocimum Gratissimum (Efinrin) also contains mineral elements such as calcium, chloride, manganese, magnesium, zinc and potassium, these constituents play contributory role in enhancing its hypoglycaemic property. The leaves consist of oil which constitutes  eugenol (a mono terpene) camphor, methyl eugenol, xanthones and lactones. The plant is however found not to be toxic to the liver. Egezie et al (2006) following the result of their experimental research stated that efinrin plant (ocimum gratissimum) is a principal antidiabetic plant due to its hypoglycemic effects. The essential oil of ocimum gratissimum has antinociceptive properties. Nociceptors are nerves which sense and respond to parts of the body which suffer damage. Nociception is a term commonly used to refer to the perception of pain.

AIMS AND OBJECTIVES

ü To determine phytochemicals (both quantitative and qualitative) present in the chloroform extracts of O. gratissimum leaves.

ü To determine the anti-oxidant property of the extract.

ü To ascertain the specific bioactive compounds present in the extract through GC-MS analysis.

CHAPTER ONE

1.0            LITERATURE REVIEW

1.1     OCIMUM GRATISSIMUM

O. gratissimum has been used extensively in the traditional system of medicine in many countries. In the North east of Brazil, it is used for medicinal, condiment and culinary purpose. The flowers and the leaves of this plant are rich in essential oils; it is therefore used in preparation of teas and infusion (Rabelo et al, 2003). In the coastal areas of Nigeria, the plant is used in the treatment of epilepsy, high fever and diarrhoea (Effraim et al, 2003). In the Savannah areas decoctions of the leaves are used to treat mental illness (Akinmoladun et al, 2007). O.gratissimum is used by the Ibos of South eastern Nigeria in the management of the baby’s cord, to keep the wound surfaces sterile. It is also used in the treatment of fungal infections, fever, cold and catarrh (Ijeh et al, 2005). Brazilian tropical forest inhabitants use a decoction of O. gratissimum roots as a sedative for children (Cristiana et al, 2006). People of Kenyan and sub Saharan African communities’ use this plant for various purposes the leaves rubbed between the palms and sniffed as a treatment for blocked nostrils. They are also used for abdominal pains, sore eyes, ear infections, coughs, barrenness, fever, convulsions, tooth gargle, regulation of menstruation and as a cure for prolapse of the rectum (Matayoh et al, 2007). In India, the whole plant has been used for the treatment of sunstroke, headache, influenza, as a diaphoretic, antipyretic and for its anti-inflammatory activity (Prajapati, Oliva , Ta’nia Ueda et al, 2007, 2003, and 1980). Nigeria use the leaf extract in treatment of diarrhoea, while the cold leaf infusions are used for the relief of stomach upset and haemorrhoids (Kabir et al, 2005).

Among the various species of Ocimum, O. gratissimum finds extensive use clinically throughout the world. Formulations of the leaf essential oil of O. gratissimum (Ocimum oil) have been incorporated in a variety of bases as topical antiseptics and for use in the treatment of minor wounds, boils and pimples (Orafidiya et al, 2001). It was reported that O. gratissimum and Xylopia aethiopica in combination are used in the preparation of potions and teas for women during peuperium (Ijeh 11 et al, 2005).

In folk medicine, Ocimum gratissimum is extensively used throughout West Africa as a febrifuge, anti- malarial and anti- convulsant. The crushed leaf juice is used in the treatment of convulsion, stomach pain and catarrh. Oil from the leaves have been found to possess antiseptics, antibacterial and antifungal activities. (C.N. Ezekwesili et al., 2004). In the coastal area of Nigeria, the plant is used in the treatment of epilepsy, (Osifo, 1992), high fever (Oliver 1980) and diarrhea (Oliver, 1980 and Sofowara, 1993). While in the savannah areas decoctions of the leaves are used to treat mental illness (Abdulrahman, 1992). Clinical trials in creams formulated against dermatological disease have yielded favorable result (Edeoga and Eriata, 2001). Nutritional importance of this plant centres on its usefulness as a seasoning because of its aromatic flavour. (C.N. Ezekwesili et al., 2004). Its essential oil has mosquito repellant, insecticidal properties. The essential oil of O. gratissimum and its main component eugenol were reported to be efficient in inhibiting Haemonchus contortus. Currently, basil is mainly used as a culinary herb as well as perfumes and cosmetics.

1.2 PHYTOCHEMICALS

Plants foods contain certain natural bioactive compounds called phytochemicals that have protective or disease preventive properties (NAS, 1981). Phytochemicals (from the Greek word phyto, meaning plant) are biologically active, naturally occurring chemical compounds found in plants, which provide health benefits for humans than those attributed to macro and micronutrients (Hasler et al, 1999). They protect plants from disease and damage and contribute to the plant’s colour, aroma and flavour. In general, the plant chemicals that protect plant cells from environmental hazards such as pollution, stress, drought, UV exposure and pathogenic attack are called Phytochemicals (Cubson et al, 1998). Recently, it was clearly known that they have roles in the protection of human health, when their dietary intake is significant (Cubson et al, 1998). More than 4,000 phytochemicals have been cataloged and are classified by their protective function, physical and chemical characteristics (Meaghere et al, 1999). About 150 phytochemicals have been studied in detail (ACSP, 2000). In wide-ranging dietary, phytochemicals are found in fruits, vegetables, legumes, whole grains, nuts, seeds, fungi, herbs and spices (Mathai et al, 2000). Broccoli, cabbage, carrots, onions, garlic, whole wheat bread, tomatoes, grapes, cherries, strawberries, raspberries, beans, legumes, and soy foods are common sources (Moorachia et al, 2000).

Phytochemicals are also available in supplementary forms, but evidence is lacking that they provide the same health benefits as dietary phytochemicals (ACSP, 2000). These compounds are known as secondary plant metabolites and have biological properties such as antioxidant activity, antimicrobial effect, modulation of detoxification enzymes, stimulation of the immune system, decrease of platelet aggregation and modulation of hormone metabolism and anticancer property. There are more than a thousand known and many unknown phytochemicals. It is well-known that plants produce these chemicals to protect themselves, but recent researches have demonstrated that many phytochemicals can also protect human against diseases (Narasimga et al, 2003).

The process of analysing phytochemicals is called Phytochemistry. Phytochemical screening is a process of identifying the presence of certain phytochemical constituents in a plant. This process can give scientists the knowledge of the desirable constituents in plants. It tells not only of the presence of therapeutic agent, it also gives information on the presence of commercially important compounds such as tannins, oils, gums and precursors for the synthesis of complex compounds. The mechanism of action of phytochemicals is complementary and overlapping, these includes: antioxidants effects, immune system stimulation, and metabolism of hormone, antibacterial and antiviral effects (Srikantha and Erdom, 1984). Studies have suggested that phytochemicals may reduce the risk of coronary heart disease by preventing the oxidation of low density lipoprotein (LDL) cholesterol, thereby reducing the synthesis or absorption of cholesterol, normalizing blood pressure and clotting, and improving arterial elasticity (Mathai et al, 2000). Phytochemicals may detoxify substances that cause cancer. They appear to neutralize free radicals, inhibit enzymes that activate carcinogens, and activate enzymes that detoxify carcinogens. Phytochemicals have also been promoted for the prevention and treatment of diabetes, high blood pressure, and macular degeneration (ACSP, 2000).

1.3 CLASSES OF PHYTOCHEMICALS

1.3.1 Alkaloids

These are the largest group of secondary chemical constituents made largely of ammonia compounds comprising basically of nitrogen bases synthesized from amino acid building blocks with various radicals replacing one or more of the hydrogen atoms in the peptide ring, most containing oxygen. The compounds have basic properties and are alkaline in reaction, turning red litmus paper blue. In fact, one or more nitrogen atoms that are present in an alkaloid, typically as 1°, 2° or 3° amines, contribute to the basicity of the alkaloid. The degree of basicity varies considerably, depending on the structure of the molecule, and presence and location of the functional groups (Sarker and Nahar, 2007). They react with acids to form crystalline salts without the production of water (Firn, 2010). Majority of alkaloids exist in solid such as atropine, some as liquids containing carbon, hydrogen, and nitrogen. Most alkaloids are readily soluble in alcohol and sparingly soluble in water. Their salts are usually soluble. The solutions of alkaloids are intensely bitter. These nitrogenous compounds function in the defence of plants against herbivores and pathogens, and they are widely exploited as pharmaceuticals, stimulants, narcotics, and poisons due to their potent biological activities.

In nature, the alkaloids exist in large proportions in the seeds and roots of plants and often in combination with vegetable acids. Alkaloids have pharmacological applications as anesthetics and CNS stimulants (Madziga et al., 2010). More than 12,000-alkaloids are known to exist in about 20% of plant species and only few have been exploited for medicinal purposes. The name alkaloid ends with the suffix –ine and plant-derived alkaloids in clinical use include the analgesics morphine and codeine, the muscle relaxant (+)-tubocurarine, the antibiotics sanguinafine and berberine, the anticancer agent vinblastine, the antiarrythmic ajmaline, the pupil dilator atropine, and the sedative scopolamine (Firn, 2010). Other important alkaloids of plant origin include the addictive stimulants caffeine, nicotine, codeine, atropine, morphine, ergotamine, cocaine, nicotine and ephedrine. Amino acids act as precursors for biosynthesis of alkaloids with ornithine and lysine commonly used as starting materials. Alkaloids are significant for the protection and survival of plant because they ensure their survival against micro-organisms (antibacterial and antifungal activities), insects and herbivores (feeding deterrens) and also against other plants by means of allelopathically active chemicals (Molyneux et al, 1996). Alkaloids have many pharmacological activities including antihypertensive effects (many indole alkaloids), antiarrhythmic effect (quinidine, spareien), antimalarial activity (quinine), and anticancer actions (dimeric indoles, vincristine, vinblastine).

FIGURE 1: Structures of various Alkaloids

1.3.2 FLAVONOIDS

Flavonoids are important group of polyphenols widely distributed among the plant flora.  Structurally, they are made of more than one benzene ring in its structure (a range of C15 aromatic compounds) and numerous reports support their use as antioxidants or free radical scavengers (Kar, 2007). The compounds are derived from parent compounds known as flavans. Over four thousand flavonoids are known to exist and some of them are pigments in higher plants. Quercetin, kaempferol and quercitrin are common flavonoids present in nearly 70% of plants. Other group of flavonoids include flavones, dihydroflavoes, flavans, flavonols, anthocyanidins, proanthocyanidins, calchones, catechin and leucoanthocyanidins. Flavonoids have been reported to exert multiple biological properties including antimicrobial, cytotoxicity, anti-inflammatory as well as antitumor activities (kar, 2007). The best-described property of almost every group of flavonoids is their capacity to act as powerful antioxidants which can protect the human body from free radicals and reactive oxygen species.

The capacity of flavonoids to act as antioxidants depends upon their molecular structure. The position of hydroxyl groups and other features in the chemical structure of flavonoids are important for their antioxidant and free radical scavenging activities. On the other hand, flavonoids such as luteolin and cathechins, are better antioxidants than the nutrients antioxidants such as vitamin C, vitamin E and β-carotene. Flavonoids constitute a wide range of substances that play important role in protecting biological systems against the harmful effects of oxidative processes on macromolecules, such as carbohydrates, proteins, lipids and DNA (Atmani et al, 2009).

FIGURE 2: Basic structures of various flavonoids

1.3.3 SAPONINS

The term saponin is derived from Saponaria vaccaria (Quillaja saponaria), a plant, which abounds in saponins and was once used as soap. Saponins possess ‘soaplike’ behaviour in water, i.e. they produce foam. On hydrolysis, an aglycone is produced, which is called sapogenin. Saponins are regarded as high molecular weight compounds in which, a sugar molecule is combined with triterpene or steroid aglycone. There are two major groups of saponins and these include: steroid saponins and triterpene saponins. Two main types of steroid aglycones are known, spirostan and furostan derivatives (fig A and B respectively). The main triterpene aglycone is a derivative of oleanane (Fig C) (Bohlman et al, 1998).

Saponins are soluble in water and insoluble in ether, and like glycosides on hydrolysis, they give aglycones. Saponins are extremely poisonous, as they cause heamolysis of blood and are known to cause cattle poisoning (Kar, 2007). They possess a bitter and acrid taste, besides causing irritation to mucous membranes. They are mostly amorphous in nature, soluble in alcohol and water, but insoluble in non-polar organic solvents like benzene and n-hexane. Saponins are also important therapeutically as they are shown to have hypolipidemic and anticancer activity.

Saponins are necessary for the activity of cardiac glycosides. They may be considered a part of plants’ defence systems, and as such have been included in a large group of protective molecules found in plants named phytoanticipins or phytoprotectants (Lacaille-Dubois, 2000). Saponin mixtures present in plants and plant products possess diverse biological effects when present in the animal body. Extensive research has been carried out into the membrane permeabilising, immunostimulant, hypocholesterolaemic and anticarcinogenic properties of saponins and they have been found to significantly affect growth, feed intake and reproduction in animals (Lacaille-Dubois, 2000). These structurally diverse compounds have also been observed to kill protozoans and molluscs, to be antioxidants, to impair the digestion of protein and the uptake of vitamins and minerals in the gut, to cause hypoglycaemia, and to act as antifungal and antiviral (Takechi et al, 1999).

FIGURE 3: Basic structure of steroid (A & B) and triterpenoid saponin (C)

1.3.4 TANNINS

From a chemical point of view it is difficult to define tannins since the term encompasses some very diverse oligomers and polymers (Harbone et al, 1999). It might be said that the tannins are a heterogeneous group of high molecular weight polyphenolic compounds with the capacity to form reversible and irreversible complexes with proteins (mainly), polysaccharides (cellulose, hemicellulose, pectin, etc.), alkaloids, nucleic acids and minerals, etc. (Mueller-Harvey et al, 1992). Tannins are soluble in water and alcohol and are found in the root, bark, stem and outer layers of plant tissue. Tannins have a characteristic feature to tan, i.e. to convert things into leather. They are acidic in reaction and the acidic reaction is attributed to the presence of phenolics or carboxylic group (Kar, 2007).

Tannins are found commonly in fruits, examples are: grapes, persimmon, blueberry, tea, chocolate, legume forages, legume trees like Acacia spp., Sesbania spp., in grasses e.g. sorghum and corn, etc. (Giner-Chavez, 1996). Several health benefits have been recognized for the intake of tannins. Some epidemiological associations with the decreased frequency of chronic diseases have also been established (Serrano et al, 2009). In medicine, especially in Asian (Japanese and Chinese) natural healing, the tannin-containing plant extracts are used as astringents against diarrhoea, as diuretics against stomach and duodenal tumours (De Bruyne, 1999), and as anti-inflammatory, antiseptic, antioxidant and haemostatic pharmaceuticals (Dolara et al, 2005). Tannins are used in the dyestuff industry as caustics for cationic dyes (tannin dyes), and in the production of inks (iron gallate ink). In the food industry tannins are used to clarify wine, beer, and fruit juices. Other industrial uses of tannins include textile dyes, as antioxidants in the fruit juice, beer, and wine industries, and as coagulants in rubber Production (Gyamfi et al, 2002).

1.3.5 TERPENES

Terpenes are among the most widespread and chemically diverse groups of natural products. They are flammable unsaturated hydrocarbons that exist in liquid form. They are commonly found in essential oils, resins or oleoresins (Firn, 2010). Terpenoids include hydrocarbons of plant origin with the general formula (C5H8)n and are classified as mono-, di-, tri- and sesquiterpenoids depending on the number of carbon atoms. Examples of commonly important monterpenes include terpinen-4-ol, thujone, camphor, eugenol and menthol. Diterpenes  are classically considered to be resins and taxol, the anticancer agent, is the common example. The triterpenes include steroids, sterols, and cardiac glycosides with anti-inflammatory, sedative, insecticidal or cytotoxic activity. Common triterpenes: amyrins, ursolic acid and oleanic acid sesquiterpene like monoterpenes, are major components of many essential oils (Martinez et al., 2008). The sesquiterpene acts as irritants when applied externally and when consumed internally their action resembles that of the gastrointestinal tract irritant. They function as phytoalexins in plant direct defense, or as signals in indirect defense responses which involves herbivores and their natural enemies (McCaskill D, 1998). Many plants produce volatile terpenes in order to attract specific insects for pollination or otherwise to expel certain animals using these plants as food. Less volatile but strongly bitter-tasting or toxic terpenes also protect some plants from being eaten by animals (antifeedants) (Degenhardt et al, 2003). Terpenes play an important role as signal compounds and growth regulators (phytohormones) of plants, as shown by preliminary investigations. In addition, terpenoids can have medicinal properties such as anticarcinogenic (e.g. perilla alcohol), antimalarial (e.g. artemisinin), anti-ulcer, hepaticidal, antimicrobial or diuretic (e.g. glycyrrhizin) activity, the sesquiterpenoid antimalarial drug artemisinin and the diterpenoid anticancer drug taxol (Langenheum JH, Dudareva et al, 1994,2004).

1.3.6 PHENOLICS

Phenolics, phenols or polyphenolics are chemical components that occur ubiquitously as natural colour pigments responsible for the colour of fruits of plants. Phenolics in plants are mostly synthesized from phenylalanine via the action of phenylalanine ammonia lyase (PAL). They are very important to plants and have multiple functions. The most important role may be in plant defence against pathogens and herbivore predators, and thus they are applied in the control of human pathogenic infections (Puupponen- Pimiä et al., 2008). They are classified into (i) phenolic acids and (ii) flavonoid polyphenolics

(flavonones, flavones, xanthones and catechins) and (iii) non-flavonoid polyphenolies. Caffeic acid is regarded as the most common of phenolic compounds distributed in the plant flora followed by chlorogenic acid which is known to cause allergic dermatitis among humans (Kar, 2007). Phenolics represent a host of natural antioxidants, used as nutraceuticals, and found in apples, green-tea, and red-wine for their enormous ability to combat cancer. They are thought to prevent heart ailments to an appreciable degree and they are sometimes anti-inflammatory agents. Other examples include flavones, rutin, naringin , hesperidin and chlorogenic acid. Phenolic acids possess diverse biological activities. Examples include: antiulcer, anti- inflammatory, antioxidant (Silva, 2007), cytotoxic, antitumor, antispasmodic and antidepressant activities (Ghasemadeh et al, 2010)

FIGURE 4: Basic structures of some pharmacologically important plant derived phenolics

1.4 Mechanism of action of phytochemicals

Different mechanisms of action of phytochemicals have been suggested. They may inhibit microorganisms, interfere with some metabolic processes or may modulate gene expression and signal transduction pathways (Kris-Etherton et al., 2002; Manson 2003; Surh 2003). Phytochemicals may either be used as chemotherapeutic or chemo preventive agents with chemoprevention referring to the use of agents to inhibit, reverse, or retard tumorigenesis. In this sense chemo preventive phytochemicals are applicable to cancer therapy, since molecular mechanisms may be common to both chemoprevention and cancer therapy (D’Incalci et al., 2005; Sarkar & Li, 2006). Plant extracts and essential oils may exhibit different modes of action against bacterial strains, such as interference with the phospholipids bilayer of the cell membrane which has a consequence permeability increase and loss of cellular constituents, damage of the enzymes involved in the production of cellular energy, synthesis of structural components, and destruction or inactivation of genetic material. In general, the mechanism of action is considered to be the disturbance of the cytoplasmic membrane, disrupting the proton motive force, electron flow, active transport, and coagulation of cell contents (Kotzekidou et al., 2008).  One of the mode of actions is discussed below.

 1.4.1 Antioxidants

Antioxidants protect cells against the damaging effects of reactive oxygen species otherwise called, free radicals. Examples are singlet oxygen, super oxide, peroxyl radicals, hydroxyl radicals and peroxynite which results in oxidative stress leading to cellular damage (Mattson & Cheng, 2006). Natural antioxidants play a key role in health maintenance and prevention of the chronic and degenerative diseases, such as atherosclerosis, cardiac and cerebral ischema, carcinogenesis, neurodegenerative disorders, diabetic pregnancy, rheumatic disorder, DNA damage and ageing (Uddin et al., 2008; Jayasri et al., 2009).

Antioxidants exert their activity by scavenging the ‘free-oxygen radicals’ thereby giving rise to a fairly ‘stable radical’. The free radicals are metastable chemical species, which tend to trap electrons from the molecules in the immediate surroundings. These radicals if not scavenged effectively in time, they may damage crucial bio molecules like lipids, proteins including those present in all membranes, mitochondria and, the DNA resulting in abnormalities that could lead to disease conditions (Uddin et al. 2008). Free radicals are involved in a number of diseases including; tumour inflammation, hemorrhagic shock, atherosclerosis, diabetes, infertility, gastrointestinal ulcerogenesis, asthma, rheumatoid arthritis, cardiovascular disorders, cystic fibrosis, neurodegenerative diseases (e.g. parkinsonism, Alzheimer’s diseases), AIDS and even early senescence (Chen et al., 2006; Uddin et al., 2008). The human body produces insufficient amount of antioxidants which are essential for preventing oxidative stress. Free radicals generated in the body can be removed by the body’s own natural antioxidant defences such as catalases (Sen, 1995). Natural exogenous antioxidants, such as vitamin C, vitamin E, flavones, ┚-carotene and natural products in plants can be used (Madsen and Bertelsen, 1995; Rice-Evans et al., 1997; Diplock et al., 1998).

Plants contain a wide variety of free radical scavenging molecules including phenols, flavonoids, vitamins and terpenoids that are rich in antioxidant activity (Madsen & Bertelsen, 1995; Cai & Sun, 2003). Many plants, citrus fruits and leafy vegetables are the source of ascorbic acid, vitamin E, carotenoids, flavanols and phenolics which possess the ability to scavenge the free radicals in the human body. Significant antioxidant properties have been recorded in phytochemicals that are necessary for the reduction in the occurrence of many diseases (Hertog & Feskens, 1993; Anderson & Teuber, 2001). Antioxidants are often added to foods to prevent the radical chain reactions of oxidation, and they act by inhibiting the initiation and propagation step that leads to the termination of the reaction and delay the oxidation process. Due to safety concerns of synthetic compounds, food industries have focused on finding natural antioxidants to replace synthetic compounds. In addition, there is growing trend in consumer preferences for natural antioxidants, all of which has given more impetus to explore natural sources of antioxidants.

 

Keywords: PHYTOCHEMICAL CONSTITUENTS AND ANTIOXIDANT ACTIVITIES OF THE CHLOROFORM EXTRACT OF OCIMUM GRATISSIMUM PLANT

 


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Keywords: PHYTOCHEMICAL CONSTITUENTS AND ANTIOXIDANT ACTIVITIES OF THE CHLOROFORM EXTRACT OF OCIMUM GRATISSIMUM PLANT

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