CHAPTER ONE
1.1 INTRODUCTION
Diabetes mellitus (DM) is positioned seventh among the various leading causes of death and considered third when its fatal complications are attentively regarded ( Ekeocha et al., 2012). Diabetes is one of the major disease that causes death in most countries. It is a chronic disease due primarily to a disorder of carbohydrate metabolism with a deficiency or diminished effectiveness of insulin resulting in chronic hyperglycaemia and glycosuria. (Kumar et al., 2015). Diabetes is also known to be involved in lipid metabolism and oxidative stress( Adewole et al., 2009). Hyperglycaemia causes an increase in oxidative stress, causing inflammation, activation of the polyol pathway, and damage to various organs in the body (Zeinab et al., 2018). Hyperglycemia increases the level of diacylglycerol and activates protein kinase C activity in the aorta of streptozotocin (stz.) induced diabetic rats ( Chattopadhyay et al., 2005). In Nigeria there has been active development of phyto pharmaceuticals with proven efficacy in a variety of medicinal problems (Ekeocha et al. 2012).Research has shown that a number of anti diabetic plants consists of useful properties such as antihypertensive, nephro protective and retino protective activities apart from their hypoglycaemic activity which may be useful against the most common complications of DM. Thus, consumption of these vegetable plants and local herbs are believed to contribute positively to the improvement of human health, because plants have long served as a useful and natural source of the therapeutic agents in terms of prevention and, or cure of diseases useful in the control of DM and its complications by man. The World Health Organization has approved medical centres to use herbal drugs to treat DM in addition to its complications although, there are no ultimate and specific method available to prevent and treat DM, but methods are needed to reduce the complications brought about by the disease ( Zeinab et al., 2018 and Arhoghro et al, 2009).
Medicinal plants have great impact in reduction of blood glucose level as well as other DM- related compounds (Raks et al., 2017). A medicinal plant is any plant that contains active ingredient which is used for therapeutic purposes and contain compounds that can be used for synthesis of useful drugs. (Kutama et al., 2018). A lot of plants are rich source of antioxidants such as flavonoids, tannins and lignin as example of phenolic compounds, vitamins A, C, E are all found in plants (Ammar et al., 2017) Leaves, roots, rhizomes, stems, barks, flowers, fruits, grains, or seeds are part of plants been used and they all contain chemical components which are used for control and treatment of a diseases (Kutama et al., 2018). Therefore, medicinal plant are being preferred these days with less or no side effects (Kumar et al., 2015). Vernonia amygdalina locally known as ‘bitter leaf’ is an example of medicinal plants widely used in Nigeria for both therapeutic and nutritional purposes for the treatment and management of diabetes, skin disease, hypertention and other metabolic diseases associated with the liver (Arhoghro et al., 2009). V.amygdalina is been assessed in the control of lipid complications and oxidative stress usually associated with chronic diabetes.
