THE EFFECT OF MEZONEURON BENTHAMIANUM ETHANOLIC EXTRACTS ON FASTING BLOOD SUGAR IN ADULT MALE WISTAR RATS

CHAPTER ONE

INTRODUCTION

1.1       Background of the Study

Ethnobotany and ethno-medical studies are today, recognised as the most viable methods of identifying new medicinal plants or refocusing on those earlier reported for bioactive constituents (Farnsworth, 1966). Plants which are observed to be efficacious and frequently prescribed may contain compounds that are potential   drug candidates and could rightly be recomended for further examination.

Mezoneuron benthamianum Baill. (Caesalpinoideae) is a medicinal woody climber with recurred thorn on its black stem. It is also called ‘tiger’s claw’. The leaves and roots are important medicinal parts in folk medicine. The leaves are brightly red when young and dark green when old. The stem is black with reoccurring thorns. The root is brown and hard while the shrubs are branched and its stem is a woody climber of up to 8 meters in height. M. benthamianum can be found in waste places of deciduous secondary jungle and savannah forest from Senegal to Nigeria. The plant is locally called ‘amuranju’ or ‘jenifiran’ in Yoruba land of Nigeria (Mathema et al., 2011)

Red  onion  or  shallot  (Allium  ascalonicum)  belongs  to  family  of  Alliaceae,  is commonly used in many Asian dishes. Its medicinal properties were well known as common cold treatment. Since, it is rich of flavonoids including quercetin, a potent antioxidant (Griffiths  et  al.,  2002).  This compound was reported to protect against oxidative stress induced by spontaneous hypertension (Duarte et al., 2001) and also able to prevent nitric oxide increase in streptozotocin (STZ) treated rats (Coskum et al., 2005), and to increased blood testosterone and sperm quality in diabetic rats (Khaki et al., 2009).

Allium ascalonicum Linn. (Liliaceae), commonly called shallot and spring onion, is an annual herbaceous plant widely found in Nigeria. The plant, widely used to flavor food, is locally known in the country as Alubosa-elewe, Albasa and Maigo. Ethnobotanical survey conducted among traditional medicine practitioners, who engage in herbalism, in Mushin area of Lagos State, Nigeria, revealed wide application of A. ascalonicum in the treatment of CNS related disorders.

Extraction, as the term is used pharmaceutically, involves the separation of medicinally active portions of plant or animal tissues from the inactive or inert components by using selective solvents in standard extraction procedures. The products so obtained from plants are relatively impure liquids, semisolids or powders intended only for oral or external use.

These include classes of preparations known as decoctions, infusions, fluid extracts, tinctures, pilular (semisolid) extracts and powdered extracts. Successful determination of biologically active compounds from plant material is largely dependent on the type of solvent used in the extraction procedure. Properties of a good solvent in plant extractions includes, low toxicity, ease of evaporation at low heat, promotion of rapid physiologic absorption of the extract,  preservative  action,  inability  to  cause  the extract to complex or dissociate. In most cases, water and ethanol are mostly used.

Phytochemicals and antioxidant constituents in plant material have raised interest among scientists, food manufacturers, producers, and consumers for their roles in the maintenance of human health (Milner, 1999). Numerous epidemiological studies suggest that diets rich in phytochemicals and antioxidants execute a protective role in health and disease. Frequent consumption of fruits and vegetables is associated with a lowered risk of cancer, heart disease, hypertension and stroke (Wolfe & Liu, 2003). Phytochemicals are bioactive substances of plants that have been associated in the protection of human health against chronic degenerative diseases. Antioxidants are compounds that help delay and inhibit lipid oxidation and when added to foods tend to minimize rancidity, retard the formation of toxic oxidation products, help maintain the nutritional quality and increase their shelf life. The major groups of phytochemicals that may contribute to the total antioxidant capacity (TAC) of plant foods include polyphenols, carotenoids and the traditional antioxidant vitamins such as vitamin C and vitamin E. The vitamins are, however, not the only phytochemicals that can have a positive effect on the health of consumers. There are other phytochemicals present in plant foods that may have positive effects on the health of consumers and need further investigation. These phytochemicals may be present in small amounts but may be very important to the health of consumers.