ABSTRACT

The immuno-modulating effects of leaf extracts of Telfairia occidentalis (Hook F) and Tectona grandis (Linn) on both humoral and cell mediated immune responses were evaluated in vivo. The responding cells were defined by flow cytometry and secretion of various cytokines by ELISA. Structural elucidation of the bioactive molecules responsible for the observed effect was equally attempted. Results of the quantitative phytochemical analyses of the extracts revealed abundance of bioactive compounds such as soluble carbohydrates (1.624 ± 0.002; 0.910 ± 0.003 mg/100g), tannin (6.593 ± 0.228; 5.325 ± 0.526 mg/1 00g), flavonoids (3.780 ± 0.228; 3.285 ± 0.526 mg/100g), saponins (3.285 ± 0.526; 0.744 ± 0. 004 mg/g), reducing sugars (293.364 ± 0.002; nil mg/100g), glycosides (8.683 ± 0.003; nil mg/g), terpenoids (2.436 ± 0.002; 2.546 ± 0.003 mg/100g), alkaloids (3.363 ± 2.247; nil mg/100g), phenol (8.574 ± 0.002; 8.096 ± 4.494 mg/100g) and hydrogen cyanide (0.395 ± 0.004; 0.344 ± 0.004 mg/g) for Telfairia and Tectona respectively. Acute toxicity studies carried out on the extracts showed no mortality or adverse reaction to the test mice up to a dose of 5000 mg/kg body weight which indicates that they are safe for consumption. The first stage of this study investigated the immune-modulating effect of aqueous and ethanol leaf extracts of Telfairia occidentalis and Tectona grandis on immune-compromised and non-immune-compromised rats. 

The study has provided compelling evidence for an immune-modulatory effect of the extracts investigated. It also confirmed that this effect is mediated via action on cytokine expression and synergistic anti-oxidant activity and that moderate boiling does not affect this effect adversely. The two plant extracts performed similarly in most of the parameters determined. 

CHAPTER ONE

INTRODUCTION

The reality of our modern society shows a preponderance of activities that elevate free radicals generation, engender stress, ultimately weaken the immune system and increase susceptibility to infections and diseases. The immune system is a system of biological structure and processes within an organism that protect against disease. It is designed to protect the host from invading pathogens and to eliminate disease (Sharmaet al., 2004; Naga and Rajeshwari, 2014).Immune system is core to maintenance of health and general well-being and is intricately associated with the four major causes of death which include injury, infection, degenerative disorders and cancer. Immunity is concerned with the recognition and disposal of foreign materials that enter the body while immunology is the study of how immune components respond and interact, of the consequences (desirable and otherwise), of their activity and of the ways in which they can be advantageously increased or reduced. There are two aspects of immune protection, the innate response and the adaptive response (Atal et al., 1986; Guyton and Hall, 2006). Innate immunity is present at birth, and provides the first barrier against infectious micro-organisms. Adaptive immunity is the second barrier against infections. It is acquired later in life and retains a memory of the invaders it has encountered (Nworu, 2007). Innate and adaptive mechanisms can be modified by substances to either enhance or suppress the ability to resist invasion by pathogens (Williams and Barclay1988).

The immune system is known to be involved in the etiology as well as the pathophysiologic mechanism of many diseases (Kalpeshet al., 2009). Immunology is thus probably one of the most rapidly developing areas of biomedical research holding great promise with regard to prevention and treatment of a wide range of disorders (Patilet al., 2012). Key elements of the immune response include recognition of self and non-self (Karlsen and Dryberg, 1998), regulation of immune response (Jerne, 1984); termination of immune response after effective control of offending agent (Parjis and Abbas, 1998) and establishment of a repertoire of memory cells for the future. The rise in immunological disorders confronting mankind today is alarming. This rise is due to different etiologies including environmental and nutritional habits. Disorders of the immune system include multiple sclerosis, arthritis, congestive heart failure, autoimmune disorders, several inflammatory disorders and infectious diseases such as AIDS, malaria, typhoid fever and the most dreaded Ebola virus disease. Immune function disorder is responsible for these and other diseases (Patwardhan et al.,1990). The immune system can be influenced by nutritional/metabolic status (Procaccini et al., 2013). Agents that alter the immune system either by stimulating or suppressing it are of great significance in managing.