ABSTRACT
The percentage phytochemical composition of the leaves of pawpaw, bitter kola, tetrapleura, neem and ginger was investigated using the methods of the association of analytical chemists, harbone and the Alkaline picrate method. The saponin content of papaw, though not significantly different from bitter kola, was the highest among other plants while ginger had the least. Papaw and ginger whose tannin contents were statistically the same contained higher quantities of tannins than other plants while bitter kola contained the least. Results show that the cyanogenic glucoside contents of the plants were below the toxic level for man. The presence of tannins in all the plants investigated indicated that they could be used in the treatment of burns and wounds. Finally, the high alkaloid and flavonoids contents of the plants, suggests their antioxidant potentials and justifies their therapeutic actions, which could be used in drug formation.
CHAPTER ONE
INTRODUCTION
1.1 Background of the Study
Phytochemicals are compounds that occur naturally in plants. They contribute to the color, flavour, and smell of plants. In addition, they form part of a plant’s natural defence mechanisms against diseases. Their therapeutic values to human health and disease prevention have been reported (Okwu, 2004)
Pawpaw (Carica papaya) is a plant that belongs to the family of caricaceae. It is a herbaceous succulent plant with self-supporting stems. Elizabeth (1994) has reported that unripe pawpaw fruits has therapeutic potential on patients with ulcer and impotence. Pawpaw plants produce natural compounds (Annonaceous acetogenins) in leaf bark and twig tissues that posses both highly anti-tumor and pesticide properties. It has been suggested that a potentially lucrative industry based simply on production of plant biomass could develop for production of anti-cancer drugs, pending food and Drug Agency approval, and natural pesticides. The high level of natural self-defence compounds in the plant makes it highly resistant to insect and disease infestation. Pawpaw leaf extract has been reported as a tumor-destroying agent (Walter, 2008).
Fresh green papaw leaf possesses antiseptic properties, while the brown, dried leaf can serve as a tonic and blood purifier. Chewing the seeds of ripe pawpaw has a therapeutic value due to its antiseptic quality. It cleans the intestines from bacteria, more so that only a healthy intestine is able to absorb vitamin and minerals, especially vitamin B12. Tea, prepared with the green papaya leaf, promotes digestion and aids in the treatment of ailments such as chronic indigestion, overweight, obesity, arteriosclerosis, high blood pressure and weakening of the heart (Mantok, 2005). Although there is sufficient information on the phytochemical constitutes of the fruits, there is scarcity of such information on the leaves.
Biter Kola (Garcinia cola) is also known as an Africa wonder nut. It comes from Garcinia cola trees, which belong to the family of Clusiaceas and it grows in the coastal rainforests in the south western and south Eastern parts of Nigeria. Traditionally these nuts were chewed as a masticatory substance, to stimulate the flow of saliva (Leakey, 2001) but are now widely consumed as snack in West and central Africa. The kernels of the nuts are widely traded and eaten as a stimulant. Bitter kola is believed to clean the digestive system, without side effects such as abdominal problems, even when a lot of the nuts are eaten. In folk, G. Kola is used in folklore remedies for the treatment of ailments such as liver disorders, hepatitis, diarrhea laryngitis, bronchitis and gonorrhea (Iwu, 1993). The seed is masticatory and also used to prevent and relieve colic, chest colds, cough and can as well be used to treat headache. This plant can be used for the treatment of jaundice, high fever and as a purgative. The plant is also found useful in the treatment of stomach ache and gastritis.
The phytochemical compounds isolated from G. Kola include Oleoresin, tannins, saponins, alkaloids cardiac glycosides. Other phytochemical compounds so far isolated from G. Kola seeds are biflavonoids such as kola flavone and 2-hydroxybi-flanoids (Okunji et al, 2002). However, there is paucity of such information on the leaves.
Tetrapleura tetraptera, one of the medicinal plants in Nigerian, is known in the South eastern Nigeria as “Uhiokiriho”. The documented biological or pharmacological activities are found to be molluscidal, cardiovascular, neuromuscular, hypotensive, anti conversant, anti-ulcerative, anti-inflammatory and anti-microbial. The pods notably have an appealing culinary use for mothers from the first day of delivery to post parturition and as a lactation aid. The dry fruit has a characteristic pleasant aroma which makes it a popular seasoning spice in the southern and Eastern Nigeria (Essient et al, 1994). At the same time, most of the folkloric chains agree in the traditional use of the fruit for management of convulsion, leprosy, inflammation and rheumatoid pains.
Neem (Azdirichta inidca) commonly called “Indian Lilac” belongs to the family “Meliaceae”. In Nigeria, the plant is known by the name “Dogonyaro”. Neem possesses maximum useful non-wood products (leaves, bark, flowers, fruits, seed, gum, oil, and neem cake) than any other three species. These non-wood products are known to have anti-allergenic, anti-dermatic, anti-feedent, anti-fungal, anti-inflammatory, anti-pyorrhoeic, antiscabic, diuretic, insecticidal, larvicidal, nematicidal, spermicidal and other biological activities. Because of these activities, neem has found enormous applications making it a green treasure. The extracts from neem are recommended in ancient medicinal texts for gastrointestinal upsets, diarrhea and intestinal infections, skin ulcers and infections, and malaria (Schmutterer, 1995).
Ginger (Zingiber officinale Roscoe) is a widely used herb and food – flavouring agent. Its neutraceutical properties have long been of interest to the food processing and pharmaceutical industries. The roots are commonly used as spices. It is medicinally used for its antioxidants, androgenic and hypoglycemic actions.
This work is thus targeted at investigating the phytochemical constituents of the leaves of these five Nigerian plants. Pawpaw, tetraplaura, Bitter kola, Neen and Ginger.
1.2 Aims of the Study
The aim of this work is to investigate the chemical compounds present in the leaves of these medicinal plants.
1.3 Statement of Problem
Before the advent of drugs, barks of trees, leaves, roots, etc have been used to cure ailments. Then I want to carry out analysis to know the constituents of these plants that helps to heal ailments, and as well to know if these chemical compounds present in these leaves have any side effect on those that consume them.
1.4 Significance of the Study
This work will help the general public
· To know the constituents of these plants
· To know the type of ailment each plant can heal
· To know if it has any side effect on the consumer
1.5 Scope of the Study
The area this work mostly covered is Aku in Igbo Etiti Local Government Area in Enugu State where these leaves were collected for analysis.
1.6 Limitation of the Study
This work was carefully researched, but due to financial problem and power failure, the work could not go the way I planed. This work will serve as a basis for those that will carry out further research.
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