ABSTRACT

The high prevalence, complications and cost of conventional drugs in the management diabetes necessitated the search for alternative treatment. As a result, this study seeks to evaluate the composition, anti-diabetic potential toxicity and tissue-protective effects of both the water and methanolic extracts of Persea americana (avocado pear) seed on alloxan-induced diabetic albino rats were investigated. This study was conceived and designed based on information on the local use of the seed in diabetes treatment. Proximate and anti-nutritional constituents of the seed were determined and 100g of the sample was extracted with 1000ml of both water and methanol using the maceration method. The extracts were evaporated to dryness using a rotary evaporator and stored at 4oC until use. The effects of different doses (200mg/kg.b.wt., 300/kg.b.wt.) of both water and methanolic extracts of P. americana seed on alloxan-induced diabetic albino rats were compared with those of a reference drug, insulin. The glucose level and weight of the rats were measured weekly for 21 days. The liver function tests and the histopathologies of the liver, and kidneys, were investigated. Results of the proximate investigation shows that the seed is rich in carbohydrate (49.03± 0.02 g/100g), lipid (17.90± 0.14 g/100g), protein (15.55± 0.36 g/100g) moisture (15.10± 0.14 g/100g) and ash (2.26±0.23 g/100g). Anti nutritional components such as total oxalate (14.98±0.03 mg/100g), tannin (6.98±0.04 mg/100g) and phytic acid (3.18±0.16 mg/1 00g). Results also showed that both the water and methanolic extracts exhibited significant anti-diabetic effects on the experimental rats. However, the methanolic extracts showed a better anti diabetic effect than the water extracts. The extracts showed no significant effects on the liver function parameters (bilirubin, conjugate bilirubin, AST, ALP and ALT) compared with the normal control but rather reversed the histopathological damage that occurred in alloxan-induced albino diabetic rats. In conclusion, the present study provides a pharmacological basis for the traditional use of P. americana seeds extracts in the management of Diabetes mellitus. It seems P. americana seed contains substantial amount of nutrients that could warrant its utilization in animal feed or food. However, further studies are required to indentify the active ingredient responsible for the anti-diabetic properties of the seed extract.

CHAPTER ONE

1.0INTRODUCTION

1.1BACKGROUND

During the past decade, the traditional systems have gained importance in the field of medicine. The World Health Organization estimates that 4 billion people, 80% of the world population (WHO, 2002), presently use herbal medicine for some aspect of primary health care (Orisataoki and Oguntibeju, 2010). Eighty percent (80%) of African populations use some form of traditional herbal medicine (WHO, 2002.) and the worldwide annual market for these products approaches US$ 60 billion (Willcox and Bodeker, 2004). Herbal medicine is a major component in all indigenous people’s traditional medicine. Medicinal plants have continued to attract attention in global search for effective methods of using plants parts (e.g. seeds, leaves, stems, roots, barks etc) for the treatment of many diseases affecting humans (Sofowora, 2008). This is as a result of the continuous need for less expensive means of disease control.

Medicinal plants are plants which can be used for therapeutic purposes or which are precursors for the synthesis of useful drugs (Sofowora, 2008). Many important drugs used in healthcare today are directly derived from plants due to its bioactive constituents such as; alkaloids, tannins, steroids, etc. Examples include L-Dopa derived fromMucuna spp used for anti-parkinsonism, another is Caffeine, a CNS stimulant derived from Camellia sinensis and Quinine from Cinchona ledgeriana and used for Antimalarial, antipyretic.