ASSESSMENT OF THE PHYTOCHEMICAL CONSTITUENTS AND PROXIMATE COMPOSITION OF AFRICAN PEER

CHAPTHER ONE

INTRODUCTION

1.1 Background of the Study

Plants are important in our everyday existence. They provide our foods, produce the oxygen we breathe, and serve as raw materials for many industrial products such as clothes, foot wears and so many others. Plants also provide raw materials for our buildings and in the manufacture of biofuels, dyes, perfumes, pesticides, adsorbents and drugs. The plant kingdom has proven to be the most useful in the treatment of diseases and they provide an important source of all the world’s pharmaceuticals. The most important of these bioactive constituents of plants are steroids, terpenoids, carotenoids, flavanoids, alkaloids, tannins and glycosides. Plants in all facet of life have served a valuable starting material for drug development (Ajibesin, 2011). Antibiotics or antimicrobial substances like saponins, glycosides, flavonoids and alkaloids etc are found to be distributed in plants, yet these compounds were not well established due to the lack of knowledge and techniques. The phytoconstituents which are phenols, anthraquinones, alkaloids, glycosides, flavonoids and saponins are antibiotic principles of plants. Plants are now occupying important position in allopathic medicine, herbal medicine, homoeopathy and aromatherapy. Medicinal plants are the sources of many important drugs of the modern world. Many of these indigenous medicinal plants are used as spices and food plants; they are also sometimes added to foods meant for pregnant mothers for medicinal purposes ( Akinpela and Onakoya, 2006). Many plants are cheaper and more accessible to most people especially in the developing countries than orthodox medicine, and there is lower incidence of adverse effects after use. These reasons might account for their worldwide attention and use. The medicinal properties of some plants have been documented by some researchers ( Akinpelu and Onukoya, 2006). Medicinal plants are of great importance to the health of individuals and communities. It was the advent of antibiotics in the 1950s that led to the decline of the use of plant derivatives as antimicrobials (Marjorie, 1999). Medicinal plants contain physiologically active components which over the years have been exploited in the traditional medical practices for the treatment of various ailments (Ajibesin, 2011). A relatively small percentage of less than 10% of all the plants on earth is believed to serve as sources of medicine (Marjorie, 1999).

In an effort to find alternative sources of feedstuffs to replace some or all of the maize in the diet of pigs and other non-ruminant farm animals, several studies have been conducted to determine the suitability of some agro-industrial wastes as feed ingredients. These include cocoa pod husks, brewers spent grains, rice bran, maize bran, groundnut skins, and wheat bran. However, one by-product that requires consideration is cashew nut testa, a by-product obtained from the processing of cashew nuts. Its utilization as animal feed even at relatively low dosage formulations will minimize its disposal problem as well as reduce the cost of animal feeding.

1.2 Statement of the Problem

It is now known that agricultural materials are used as animal feeds and that they contain phytochemicals. These phytochemicals serve as antibiotic principles of plants.

The need for a cheap, renewable, easily available and nutritive source of material as feed supplements has therefore attracted me to investigate African pear leaf, (APL) as an alternative.

1.3 Objectives of the Study

Broadly stated, the purpose of this work is to investigate/assess the nutritive and medicinal values of African pear leaf as an effective replacement in animal diets. Specifically, this work investigated:

(i) the proximate constituents of African pear leaf; and

(ii) the qualitative and quantitative phytochemicals of African pear leaf.

 

CHAPTER TWO

LITERATURE REVIEW

2.1 Dacryodes edulis

Dacryodes edulis is an oliferous fruit tree found in equatorial and humid tropic climates and originates from Central Africa and Gulf of Guinea area (Ayuk et al, 1999). Its actual geographical area spreads from nearly all over the western coast of Africa across to Uganda. It is an evergreen tree attaining a height of 18–40 m in the forest but not exceeding 12 m in plantations. It has a relatively short trunk and a deep, dense crown. The bark is pale gray and rough with droplets of resin. The leaves are a compound with 5-8 pairs of leaflets. The upper surface of the leaves is glossy. The flowers are yellow and about 5 mm across. They are arranged in a large inflorescence. The fruit is an ellipsoidal drupe which varies in length from 4 to 12 cm. The skin of the fruit is dark blue or violet, whereas the flesh is pale to light green. The tree flowers at the beginning of the rainy season and bears fruits during 2 to 5 months after flowering. There are two variants of Dacryodes edulis: D. e. var. edulis and D. e. var. parvicarpa. The fruit of D. e. var. edulis is larger and the tree has stout, ascending branches. D. e. var. parvicarpa has smaller fruit and slender, drooping branches.(Kola, et al, 2011)

The preferential habitat of D. edulis is a shady, humid tropical forest. However, it adapts well to variations in soil type, humidity, temperature and day length. The natural range extends from Angola in the South, Nigeria in the North, Sierra Leone in the West and Uganda in the East. It is also cultivated in Malaysia.

A traditional food plant in Africa, this little-known fruit has potential to improve nutrition, boost food security, foster rural development and support sustainable land care. The main use of D. edulis is its fruit, which can be eaten raw, cooked in warm salt water or roasted. Cooked flesh of the fruit has a texture similar to butter. The pulp contains 48% oil and a plantation can produce 7-8 tons of oil per hectare. It is also rich in vitamins. The kernel can be used as fodder for sheep or goats. The flowers are useful in apiculture. Shade tolerant traditional crops, such as Xanthosoma sagittifolium and taro can be co-cultivated with D. edulis.

The wood of D. edulis is elastic, greyish-white to pinkish. The wood has general use for tool handles, and occasionally for mortars, and is suitable for carpentry. The resin is sometimes burnt for lighting or used as glue. The tree is used as an ornamental plant and is known to improve soil quality by providing large quantities of biomass. The tree is also a source of many herbal medicines.

The plant has long been used in the traditional medicine of some African countries to treat various ailments such as wound, skin diseases, dysentery and fever. The extracts and secondary metabolites have been found to show biological activities such as antimicrobial, antioxidant and anti sickle-cell disease [Ajibesin, 2011]. A wide range of chemical constituents such as terpenes, flavonoids, tannins, alkaloids and saponins have been isolated from the plant [Ajibesin, 2011]. The bark of the plant has long been used to cicatrize wound in Gabon [Walker and Sillans, 1961]. In Democratic Republic of Congo, the plant is employed for the treatment of diver’s ailments. The decoction of the bark is taken orally to treat leprosy. It is used as gargle and mouthwash to treat tonsillitis [Bouquet, 1969]. The bark is comminuted with melegueta pepper to cure dysentery, anemia, spitting blood and as an emmenagogue; when mixed with palm oil, it is applied topically to relieve pains, debility, stiffness and skin diseases [Bouquet, 1969]. The leaves are chewed with kola nut as an anthelmintic. The leaf sap is used as ear drop to treat ear trouble, while a leaf decoction is prepared to produce vapour that treats fever and headache [Bouquet, 1969; Bouet, 1980]. In Congo Brazzaville, the leaves are boiled with those of Lantana camara, Cymbopogon citratus and Persea Americana in water to form a decoction for treating malaria. A steam bath can also be taken from the decoction to treat the same ailment. Boiling the leaves with those of P. Americana alone can be used to treat headache, antalgic and cephalgy [Diafouka, 1997]. Recently, Tiofack et al [2010] reported that the leaves are made into plaster to treat snakebite in southwest Cameroon. The bark resin is used in Nigeria to treat parasitic skin diseases and jiggers [Dalziel, 1937; Hutchinson et al, 1963]. When applied in lotions and creams, the resin smoothens and protects the skin [Ekpa, 1993]. The aroma of the resin when liberated through burning is believed to ward off evil spirit in Nigeria [Sofowora, 2008]. The leaves are often crushed and the juice released to treat generalized skin diseases such as scabies, ringworm, rash and wound, while the stem or stem twigs are employed as chewing sticks for oral hygiene [Igoli et al, 2005; Ajibesin et al, 2008].

2.2 Empirical studies on Dacryodes Edulis

The oil from edible African pear (Dacryodes edulis) was extracted with chloroform. The oil were characterized for melting point, refractive index, relative viscosity, free fatty acids, saponification value, iodine value, acid value and percentage unsaponifiable matter. The percent oil content in the fruit pulp was determined. The oil content of African pear was 23.2%. The fatty acid content determined in % are: palmitic (9.06), stearic (15.46), steric isomer (18.00), oleic (26.63) and linoleic (30.85). Results on physical characteristics are: average melting point (80oC), refractive index (1.456), viscosity (0.33 poise). Results on chemical characteristics are: free fatty acid (1.100%), saponification value (143.760), iodine value (44.079), acid value (15.280), ester value (128.480), unsaponifiable matter (53.920%). The physico-chemical characteristics and fatty acid composition of these oils, suggest some industrial potentials [Ikhuoria and Maliki, 2007].

The phytochemical contents and medicinal values of Dacryodes edulis exudates were investigated. Phytochemical screening of the plant showed that it contain the presence of bioactive compounds comprising saponins (2.08–3.98mg 100g−1), alkaloids (0.28–0.49 mg 100g−1), tannins (0.47–0.72 mg 100g−1), flavonoids (0.26–0.39 mg 100g−1), and phenolic compounds (0.01–0.05 mg 100g−1). The carbohydrates, lipids and protein content were 77.42–78.90%, 2.02–4.185% and 16.63–18.38% respectively. The exudate is a good source of water soluble vitamins; ascorbic acid (7.04–26.40 mg 100g−1), niacin (3.12–4.00 mg 100g−1), riboflavin (0.14–0.54 mg 100g−1) and thiamine (0.15–0.22 mg 100g−1),). The plant exudate is a good source of minerals such as Ca, Mg, P, Fe, Zn, Cu and Mn while Cr and Co were in trace values. These results indicate that exudates can be potential sources of feedstock for the pharmaceutical industry [Okwu and Nnamdi, 2008].

Some physical and chemical properties of African pear (Dacryodes edulis) samples from nine different trees were analysed in order to determine the level of differences that exist between trees. The length of the individual fruits ranged from 39.86 mm to 80.76 mm while the weight ranged from 15.97 g to 39.36 g. Significant differences (p ≥ 0.05) were observed between the samples for all the parameters measured. Fruit density showed a negative correlation (r = -0.86) with the pulp/seed ratio. Significant differences were also observed in the proximate composition of the African pear pulp. The major components of the pulp were moisture (36.5% to 53.82%), oil (18.81% to 38.36%) and protein (11.09% to 19.19%). The pulp acidity ranged from 0.92% to 1.69% expressed as citric acid [Onuegbu and Ihedioha Ma, 2008].

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