ABSTRACT

Hoslundia opposita leaf is used folklorically in the management of diabetes and a preliminary anti-hyperglycaemic activity has been reported for its methanol extract. Therefore, in this study, the antihyperglyceamic activities of the partition fractions of Hoslundia opposita leaf was investigated using glucose loaded wistar rats with a view to determine the most active fraction. A 1% Tween 80 in normal saline and glibenclamide (5 mg/kg) were used as the negative and positive controls, respectively. The methanolic extract of the plant was successively partitioned into n-hexane, chloroform, ethylacetate, and evaporated to dryness in vacuo to obtain their corresponding n-hexane, chloroform, ethylacetate and aqueous fractions, which were similarly tested for their anti-hyperglyceamic activities. Activities of the fractions were statistically compared with themselves, and those of the positive and negative controls using ANOVA, followed by Student Newman Kuels’ test to determine the most active fraction. The methanolic extract of H. opposita (200, 400 mg/kg) gave a similar profile of activity with glibenclamide probably indicating both extra-pancreatic and insulin release effects. The similar results given by 200 and 400 mg/kg confirmed that the constituents are probably acting in synergism as the extract was significantly more active than the partition fractions or the most active constituents are in the non-polar fractions. The activities of the fractions were significantly less than that of the standard drug used, glibenclamide (5 mg/kg). The comparable (p > 0.05) 20 % anti-hyperglycaemic activity given by both ethylacetate and aqueous fractions at 400 and 200 mg/kg, respectively may indicate that both demonstrated moderate anti-hyperglycaemic activity, depending on the dose. Also, since their greatest activity was at 4 h, both fractions may elicit their antihyperglycaemic activity by stimulating insulin release. Only aqueous fraction gave a possible mild extrapancreatic effect. The antihyperglycaemic constituents in these fractions are likely to be moderately polar to polar in nature. Therefore, the totality of the results established the anti-hyperglycaemic activity of H. opposita and its usage in ethnomedicinal management of diabetes.

CHAPTER ONE

1.0 INTRODUCTION Medicinal plant is any plant, which in one or more of its organs, contains substances that can be used for therapeutic purposes or which are precursors for the synthesis of useful drugs (Sofowora, 2008). The practice of using plants in treating diseases is called herbal medicine and it dates back to very earliest periods of known human history. There is evidence of the use of herbs in the treatment of diseases and for revitalising body systems in almost all ancient civilisations – The Indian, Egyptian, Chinese and even the Greek and Roman civilisations (Bakhru, 1992). The universal role of plants in the treatment of diseases is exemplified by their employment in all the major systems of medicine, irrespective of the underlying philosophical premise (Evans, 2008). Examples of different diseases that plants have been used to treat include heart disorders, digestive disorders, constipation, diarrhoea, gonorrhoea, skin diseases, stomach ache, craw craw, asthma, toothache, hypertension (Bakhru, 1992; Evans, 2008). Some drugs of importance for the treatment of various diseases, which have been obtained from plants include atropine, bromelain, caffeine, cocaine, codeine, digoxin, emetine, morphine, noscapine, pilocarpine and quinine (Ertug, 2000).