CHAPTER ONE
INTRODUCTION AND LITERATURE REVIEW
- Introduction
Psidium guajava is a plant belonging to the family Myrtaceae. It is grown in all parts of the world and cultivated for its leaf, fruit, bark, fleshy calyx root twigs or seeds. The plant has been found to thrive on a wide range of soil conditions and tolerate a pH range from 4.5 to 9.4, propagates easily, and bears fruit relatively quickly. It is also salt resistant (Morton, 1987).
Psidium guajava is commonly called Guava although it has several names in many part of the world. Such names include Bayabas, Jambu burung, Lal peyara, advaba, madhuria, kalimbahin, malakabeng etc. However in Nigeria it is known as gwaabaa (hausa) woba (Efik), ugwoba (Igbo), and guata (Yoruba) (Iwu, 1993).
The plant can be seriously attacked by pest and disease. Such pests include citrus flat mite, bark-eating caterpillars, red-banded thrips, aphids etc, which attack different part of the plant whereas diseases of guava plant include mucor rot, alga spotting, stem-end rot, etc. (Morton, 1987). Phytochemical analysis of the fruit shows that it contains vitamin A, iron, calcium and phosphorous, manganese with oxalic and malic acids, saponin, oleanolic acid, flavonoids, guaijavarine and quercetin (Iwu, 1993; Arima and Danno, 2002). Whereas the fruit skin is rich in Ascorbic acid and carbonyl compound which gives it the strong odor. The chemical analysis of the leaves shows that it contain essential oil with different component which include malic acid, menthol, guayavolic acid, flavonoids, and quercetin. In addition the leaves also contain fat, resin, mineral salt, tannin, chlorophyll, cellulose, etc. (Nadkarni and Nadkarni, 1999). Whereas the root analysis shows that it contains salt, carbohydrate, tannin, sterols etc (Iwu 1993). However, Okwu and Ekeke (2003) analysis of the twig shows that it contains essential elements which include calcium, magnesium, phosphorous potassium and sodium. In addition, it contains the micro elements like zinc, iron, copper etc. (Arima and Danno, 2002).
1.2 Justification of the study
Due to the medicinal uses of P. guajava and its potency in alternative medicine, it is therefore necessary to investigate the physiological effects of this plant material on biochemical and haematological indices using an animal model in order to make an inference on the safety of its consumption by humans.
1.3 Objectives of the study
The objectives were to:
- Compare the effects of the extracts on the body weight of the albino rats
- Determine the effects of aqueous and methanolic extracts of Psidium guajava leaves on the biochemical indices of albino rats.
- Determine the effects of aqueous and methanolic extracts of Psidium guajava leaves on the hematological indices on Albino rats.
1.4 Literature Review
1.4.1 Origin and morphology of Psidium guajava
Psidium guajava originated from Central America and Mexico, although today the plant is distributed to Africa and to the Pacific region. It is a low evergreen shrub with branches and downy twigs. It has thin smooth-copper colored bark which peels off and show its greenish layer beneath.The leaves are green due to chlorophyll pigment in them, short-petioled, oval or oblong and irregular in outline. It has conspicuous parallel veins. It has petals which are easily shed and stamen with pale-yellow anthers. The fruit has strong, sweet, musky odor. It may be round, ovoid or pear shaped with sepals at the apex.The skin is fleshy, thick, yellowish and flavorful. The central pulp is slightly darker and filled with hard yellowish seed. The seeds are chewable and are many although some are seedless. (Morton, 1987; Baby and Mini, 2011).
