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Keywords: THE PHYTOCHEMICAL CONSTITUENTS OF METHANOLIC EXTRACT OF OCIMUM GRATISSIMUM
Phytochemicals can be defined as a large group of plant-derived compounds hypothesized to be responsible for much of the disease protection conferred from diets high in fruits, vegetables, beans, cereals, and plant-based beverages such as tea and wine (Kalpana et al., 1996). Phytochemicals are non-nutritive plant chemicals that have protective or disease preventive properties. They are not required by the human body for sustaining life and are non essential nutrient. It is well-known that plant produces these chemicals to protect them but recent research demonstrates that they can also protect humans against diseases (Ncube et al., 1998).
Plants have been proved scientifically to have the ability to cure ailments by providing some necessary nutrients which may be lacking in the body or by attacking the causative organisms themselves (Adeyemi et al., 2002). Most plants are edible and contain different amount of vitamins, protein or carbohydrates which helps the body to replace worn out cells or tissues, digest food and combat ailments among other health related problems (Adeyemi et al., 2002). Since the dawn of history, man has been faced with the challenges of eliminating ailments completely, which inheritance has not been met, therefore different ages have been adopting different measures to help check ailments but from creation to date, plants have always been among the most effective primary measures for this check (Porter, 1997).
Ocimum gratissimum plant is an important vegetable. It is also known as “scent leaf”, “Efirin” in Southwestern part of Nigeria. Ocimum gratissimum is very peculiar plant in the tropics (Das et al., 2010). It has a shrub that grows up to 1-2m in height. Since ancient times, this plant has been connected with the traditional treatment of fever, hence its acronyms such as “fever plant” (Bimakr, 2010). It is commonly grown around houses as a mosquito repellant. It is found in the wild or cultivated throughout the tropics and subtropics. In West Africa, O. gratissimum is commonly found around village huts and gardens (Iwu, 1993) and cultivated for medicinal and culinary purposes. Ocimum gratissimum is a leafy vegetable, and a good source of dietary fibre, carotenoids, vitamin C, foliate, phytochemicals and certain minerals, but have low concentrations of proteins, digestible carbohydrates and lipids (Wills et al., 1998). It has interesting medicinal properties (Gill, 1992). There are many uses to which the plant is subjected to locally are incredible. To mention some of the uses, the leaf serves as a decongestant for head colds, bronchitis and sinusitis. The pulped foilage is belived to have antiseptic properties. The leaf is also chewed traditionally for all tooth and gum disorders (Bimakr, 2010). The leaves have strong aromatic odor and are popularly used to flavor soup and spice meat, especially game. In southeastern part of Nigeria and beyond, the leaves popularly serve as indispensable flavoring agent in soups, especially “pepper soup,” and other such meals. In traditional medicine practice, it is used in the treatment of diarrhea, (Dalziel, 1956; Iwu,1993) as a febrifuge and component of anti-malaria remedies, (Oliver, 1960) mosquito/insect repellant, stomachic and general tonic, antiseptic, in wound dressing, skin infections, conjunctivitis and bronchitis. An infusion of the leaves, called ‘Ocimum tea,’ is dispensed as a remedy for fever and diaphoresis. (Iwu,1993). The roots are used as sedative for children (Di Stasi et al., 2002). The ocimum oil is active against several species of bacteria (Escherichia coli, Shigella, Salmonella and Proteus) and fungi (Trichophyton rubrum ) (Nakamura et al., 1999; Nwosu and Okafor, 1995; Oboh et al., 2009). it is used in salads, soups, pastas, vinegars and jellies in many parts of the world. Extract of the crushed leaves is an excellent remedy for cough. In southeastern parts of Nigeria, in addition to serving culinary purposes, the leaves are also used for the treatment of convulsive disorders.
1.1 AIM OF STUDY
This study is aimed at investigating the phytochemical constituents of methanolic extract of Ocimum gratissimum
1.2 LITERATURE REVIEW
The phytochemical evaluation of Ocimum gratissimum in a previous study shows that it is rich in alkaloid, tannins, phytates, flavonoids and Oligosaccharides (Ijeh, et al 2004). In the coastal area of Nigeria, the plant Ocimum gratissimum is used in the treatment of epilepsy, high fever and diarrhea (Sofowora 1993). Ocimum gratissimum (Scent leaf) is a perennial plant which is widely distributed in the tropics of Africa and Asia. It belongs to the family Labiatae and it as the most abundant of the genus Ocimum. In the southern part of Nigeria, it is called “Efirin nla” by the Yoruba speaking tribe. “Nichonwu” in Igbo while in the northern part of Nigeria, it is called “Daidoga. Fruits and vegetables are the greatest sources of phytochemicals and facts have emerged that some antinutritional content of these vegetables have potentials in reducing some diseases in man (Cowan, 1999). Some of these diseases include high blood pressure, heart attack, stroke and other cardiovascular diseases. These antinutrients or phytochemicals carry out their healing activities by combining with vitamins or with other nutrients.
Foods containing phytochemicals are already part of our daily diet. In fact, most foods contain phytochemicals except for some refined foods such as sugar or alcohol (Middleton and Kandaswami, 1994). Some foods, such as whole grains, vegetables, beans, fruits and herbs, contain many phytochemicals. The easiest way to get more phytochemicals is to eat more fruit (blueberries, cranberries, cherries, apple) and vegetables (cauliflower, cabbage, carrots, broccoli). It is recommended to take daily at least 5 to 9 servings of fruits or vegetable. Fruits and vegetables are also rich in minerals, vitamins and fibre and low in saturated fat (Harborne and Williams, 2000). In previous studies, essential oil of Ocimum gratissimum contains eugenol and shows some evidence of antibacterial activity (Celso et al., 2002). A study on goats found that the essential oil has anthelmintic activity (Pessoa et al., 2002). A test on guinea pigs found evidence that the essential oil relaxes the muscles of the small intestinal disorders (Socorro et al., 2002). A study on rats found evidence that a leaf extract of the plant prevented diarrhea (Veronica and Unoma, 1999). The ocimum oil is active against several species of bacteria (Escherichia coli, Shigella, Salmonella and Proteus) and fungi (Trichophyton rubrum and Trichophyton mentagrophytes) (Nakamura et al., 1999; Nwosu and Okafor, 1995; Oboh et al., 2009). A previous screening of crude extracts of plants used in traditional medicine showed that the essential of Ocimum gratissimum inhibited growth of Herpetomonas samuelpessoai (Holetz et al., 2002).
African basil is used for a variety of reasons. In culinary, it is used in salads soups, pastas, vinegars and jellies in many parts of the world. The anti-diarrhea agent and for the treatment of conjunctivitis by instilling directly into the eyes; the leaf oil when mixed with alcohol is applied as a lotion for skin infections, and taken internally for bronchitis. The dried leaves are shuffled to alleviate headaches and fever among other uses (Iwu, 1993). Although, convectional antibiotics have been very useful in orthodox medicine it has been argued by many that its concomitant use with herbal extracts is not desirable as one normally antagonizes the activity of the other.
Considering the fact that Ocimum gratissimum is used in most local dishes or foods to achieve a variety of purposes, there is need to ascertain if its characteristics, antagonizes or acts as a synergy when used together with conventional antibiotics. In addition, despite the fact that the various extracts of Ocimum gratissimum have been tested in vitro and shown to be active against some bacterial and fungal isolates (Lemos et al., 2005; Nakamura, 1999; Nakamura et al., 2004; Silva et al., 2005), specific strain differences supposes that a lot more status of bacteria and fungi across other regions be tested to ascertain there invitro activity against this spice. In another previous study, Ocimum gratissimum is commonly used in folk medicine to treat different diseases, e.g. upper respiratory tract infections, diarrhea, headache, ophthalmic, skin diseases, pneumonia and also a treatment for cough, fever and conjuctivis (Onajobi, 1986). Although an earlier study has demonstrated the anti -convulsant, sedative and anxiolytic properties (Freire et al., 2006) of essential oil of the leaves, these activities are not clearly attributable to any specific constituent of the oil. Also, the neuropharmacological effects of non-oil constituents of the leaves are not known.
Experimental studies showed that extracts of this plant relaxed intestinal smooth muscle, (Madeira et al., 2002) exhibited antinociceptive effect, (Aziba et al., 1999; Rabelo et al., 2003) and lowered blood glucose in diabetic rats (Mohammed et al., 2007). The volatile oil has been credited with antimicrobial, anthelminthic and insect-repellant properties, (Iwu, 1993) while the essential oil exhibited sedative and anxiolytic activities (Freire et al., 2006).
Alkaloids have diverse and important physiological effects on humans and other animals. Well-known alkaloids include morphine, strychnine, quinine, ephedrine, and nicotine (Dillard and German, 2000). They have 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 (Ündeğer et al., 2009). 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 though they are sparingly soluble in water, their salts of are usually soluble. The solutions of alkaloids are intensely bitter (Hou, 1977). These nitrogenous compounds function in the defence of plants against herbivores and pathogens, and 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 (Sarker & Nahar, 2007). Alkaloids are found primarily in plants and are especially common in certain families of flowering plants. More than 3,000 different types of alkaloids have been identified in a total of more than 4,000 plant species. Alkaloids are generated by various living organisms, especially by higher plants – about 10 to 25% of those contain alkaloids. Therefore, in the past the term “alkaloid” was associated with plants (Sarker & Nahar, 2007). The alkaloids content in plants is usually within a few percent and is inhomogeneous over the plant tissues (Dillard and German, 2000). Some amines, such as adrenaline and serotonin, which play an important role in higher animals, are similar to alkaloids in their structure and biosynthesis and are sometimes called alkaloids. The medicinal properties of alkaloids are quite diverse. Morphine is a powerful narcotic used for the relief of pain, though it’s addictive properties limit its usefulness (Firn, 2010).
Flavonoids are important group of polyphenols widely distributed among the plant flora. Stucturally, 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).
Flavonoids are polyphenols of plant origin that are among the most important compounds in human diet due to their widespread distribution in foods and beverages. They can occur both in the free form (aglycones) and as glycosides, and differ in their substituent (type, number and position) and in their instauration (Muldoon and Kritchevsky , 1996). The most common classes are the flavones, flavonols, flavanones, catechins, isoflavones and anthocyanidins, which account for around 80 % of flavonoids. Over 4,000 flavonoids have been identified, many of which occur in fruits, vegetables and beverages (tea, coffee, beer, wine and fruit drinks). Flavonoids have aroused considerable interest recently because of their potential beneficial effects on human health (Arai et al., 2000).
They also have long been recognized to possess antiinflammatory, antiallergic, hepatoprotective, antithrombotic, antiviral, and anticarcinogenic activities.
22.214.171.124 Antioxidant activity
The best-described property of almost every group of flavonoids is their capacity to acts as antioxidant. Antioxidants are compounds that protect cells against the damaging effects of reactive oxygen species, such as singlet oxygen, superoxide, peroxyl radicals, hydroxyl radicals and peroxynitrite (De-whallely et al., 1990). An imbalance between antioxidants and reactive oxygen species results in oxidative stress, leading to cellular damage. Oxidative stress has been linked to cancer, aging, atherosclerosis, ischemic injury, inflammation and neurodegenerative diseases (Parkinson’s and Alzheimer’s).
126.96.36.199 Antimicrobial activity
Flavonoids and esters of phenolic acids have also been investigated for their antibacterial, antifungal and antiviral activities (Havsteen, 1983).
188.8.131.52 Antibacterial activity
Antibacterial activity has been displayed by a number of flavonoids. Quercetin has been reported to completely inhibit the growth of Staphylococcus aureus (De-whallely et al., 1990). Most of the flavonones having no sugar moiety showed antimicrobial activities whereas none of the flavonols and flavonolignans tested showed inhibitory activity on microorganisms (Havsteen, 1983).
184.108.40.206 Antiatherosclerotic effects
Oxidative modification of low-density lipoproteins (LDL) by free radicals is an early event in the pathogenesis of atherosclerosis. The rapid uptake of oxidatively-modified LDL via a scavenger receptor leads to the formation of foam cells. Flavonoids may directly scavenge some radical species by acting as a chain braking antioxidant (De-whallely et al., 1990). The ability of quercetin and the quercetin glycosides to protect LDL against oxidative modification has shown a significant protective effect (Fuhrman et al., 1995). Furthermore, a Japanese study reported an inverse correlation between flavonoid intake and total plasma cholesterol concentrations (Arai et al.,2000). Flavonoids may help provide protection against these diseases by contributing, along with antioxidant vitamins and enzymes, to the total antioxidant defense system of the human body. Epidemiological studies have shown that flavonoids intake is inversely related to mortality from coronary heart disease and to the incidence of heart attacks (Dillard and German, 2000). The recognized dietary antioxidants are vitamin C, vitamin E, selenium, and carotenoids. However, recent studies have demonstrated that flavonoids found in fruits and vegetables may also act as antioxidants. Like alpha-tocopherol (vitamin E), flavonoids contain chemical structural elements that may be responsible for their antioxidant activities (Harborne and Williams, 2000). The contribution of flavonoids to the antioxidant defense system may be substantial considering that the total daily intake of flavonoids can range from 50 to 800 mg. This intake is high compared to the average daily intake of other dietary antioxidants like vitamin C (70 mg), vitamin E (710 mg) or carotenoids (23 mg). Flavonoid intake depends upon the consumption of fruits, vegetables, and certain beverages, such as red wine, tea, and beer. The high consumption of tea and wine may be most influential on total flavonoid intake in certain groups of people (Middleton et al., 1994).
Saponins are an important class of natural products first discovered in higher plants where they are widely spread (Li et al., 2006). In the search for new pharmacologically active substances, saponin have also been isolated from marine organisms such as holothurians (Nigrelli 1952; Yamanouchi 1955), seastars (Mackie and Turner 1970) and sponges (Thompson et al., 1985). Saponins (or ginsengosides), a sweet-bitter material, usually exist in plants in the form of glycosides known as “saponin glycosides” (Hou, 1977). Saponin glycosides are macromolecules and are composed of a “sugar” (glycone) and a “non-sugar” (aglycone). Saponins are a class of chemical compounds, one of many secondary metabolites found in natural sources, with saponins found in particular abundance in various plant species.
Specifically, they are amphipathic glycosides grouped phenomenologically by the soap-like foaming they produce when shaken in aqueous solutions, and structurally by their composition of one or more hydrophilic glycoside moieties combined with a lipophilic triterpene derivative (Nigrelli 1952).
Saponins have historically been understood to be plant-derived, but they have also been isolated from marine organisms. Saponins are indeed found in many plants, and derive their name from the soapwort plant (Genus Saponaria, Family Caryophyllaceae), the root of which was used historically as a soap. Saponins are also found in the botanical family Sapindaceae (Yamanouchi 1955)
The name ‘tannin’ is derived from the French ‘tanin’ (tanning substance) and is used for a range of natural polyphenols. Tannins are complex polyphenolics found widely in plant kingdom (Hargerman and Butler, 1978). They are found in leaves, twigs, flower, fruits, tree barks. The tannins appear as light yellow or white amorphous powders or shiny, nearly colourless, loose masses, with a characteristic strange smell and astringent taste (Falbe and Regitz, 1995). The tannins are applied widely, with uses ranging from tanning, known over millennia, through medicinal uses to uses in the food industry. In medicine, especially in Asian (Japanese and Chinese) natural healing, the tannin-containing plant extracts are used as astringents, against diarrhoea, (Yoshida et al., 1991) as diuretics, (Okudaet al.,1983) (Hatanoet al., 1991) against stomach and duodena tumours, (Saijoet al., 1989) and as antiinflammatory, antiseptic, and haemostatic pharmaceuticals (Haslam, 1989). As tannins can precipitate heavy metals and alkaloids (except morphine), they can be used in poisonings with these substances. It is also becoming clear that tannins often are the active principles of plant-based medicines (Haslam, 1996).
Tannins are used in the dyestuff industry as caustics for cationic dyes (tannin dyes), and also in the production of inks. In the food industry tannins are used to clarify wine, beer, and fruit juices (Würdig et al., 1989). Other industrial uses of tannins include textile dyes, as antioxidants in the fruit juice, beer, and wine industries, and as coagulants in rubber production (Falbe and Regitz, 1995). These are widely distributed in plant flora. Tannins are usually found in large quantities in the bark of trees where they act as a barrier for micro-organisms and protect the tree. Apart from tanning, tannins are also used in dyeing, photography, refining beer and wine as well as an astringent in medicines. Significantly, tannins form a vital element of tea (Nonaka et al., 1981). They are phenolic compounds of high molecular weight. 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). They form complexes with proteins, carbohydrates, gelatin and alkaloids. Tannins are divided into hydrolysable tannins and condensed tannins. Tannin rich medicinal plants are used as healing agents in a number of diseases On the basis of their structural characteristics. Tannins are also beneficial when applied to the mucosal lining of the mouth (Stéphane et al., 2004). Tannins can also be effective in protecting the kidneys. Tannins have been used for immediate relief of sore throats, diarrhea, dysentery, hemorrhaging, fatigue, skin ulcers (Akiyama et al., 2001; Funatogawa et al., 2004) Tannins can cause regression of tumors that are already present in tissue, but if used excessively over time, they can cause tumors in healthy tissue. They have been also reported to have anti-viral (Lin et al.,2004; Kolodziej et al., 2005).
Keywords: THE PHYTOCHEMICAL CONSTITUENTS OF METHANOLIC EXTRACT OF OCIMUM GRATISSIMUM