Thesis Abstract

Abstract
Combretum micranthum, a plant widely distributed in tropical Africa, has been traditionally used for its medicinal properties. This study aimed to investigate the angiotensin-converting enzyme (ACE) inhibitory activity and antioxidant properties of the aqueous extract of Combretum micranthum leaves. The ACE inhibitory activity was evaluated using an in vitro assay, while various antioxidant assays were employed to determine the extract's antioxidant potential. The results indicated that the aqueous extract of Combretum micranthum leaves exhibited significant ACE inhibitory activity, with an IC50 value of 0.32 mg/mL. This suggests the potential of the extract as a natural ACE inhibitor, which could be beneficial for managing hypertension. Additionally, the extract demonstrated potent antioxidant activities in various assays, including DPPH radical scavenging, ABTS radical scavenging, and reducing power assays. The extract showed dose-dependent antioxidant activity, indicating its ability to neutralize free radicals and protect against oxidative stress. Furthermore, the phytochemical analysis of the extract revealed the presence of various bioactive compounds, such as flavonoids, phenolics, and tannins, which are known for their antioxidant properties. These compounds may contribute to the observed ACE inhibitory and antioxidant activities of the extract. The total phenolic content of the extract was found to be 74.5 mg GAE/g, indicating a rich source of phenolic compounds with potential health benefits. Overall, the aqueous extract of Combretum micranthum leaves exhibited promising ACE inhibitory activity and potent antioxidant properties. These findings support the traditional use of this plant in herbal medicine and suggest its potential for the development of natural remedies for hypertension and oxidative stress-related conditions. Further studies are warranted to elucidate the underlying mechanisms of action, isolate and identify specific bioactive compounds responsible for the observed activities, and evaluate the extract's efficacy in animal models and clinical trials. This research contributes to the growing body of evidence supporting the therapeutic potential of natural products derived from medicinal plants.

Thesis Overview

1.0 INTRODUCTION

1.1 Background of the Study

The word hypertension is defined as a persistence increase in systemic arterial blood pressure (Sembulingam and Sembuligam, 2006). Clinically, when the systolic pressure remains elevated above 140mmHg and diastolic pressure remains elevated above 90mmHg, it is considered as hypertension. The prevalence varies with age, race, education, occupation and many other variables (Benowitz, 2009). In Nigeria for example, the true incidence of hypertension remains unknown but its prevalence among male and female is estimated to be 11.2% with age adjusted figure of 9.3% (Nurudeenet al., 2013). This translates into approximately 13.4 million Nigerians becoming hypertensive at the age of 15years and above, using the projected national population census figure of 120million (Akinkungbe, 1998). In fact, hypertension is reported to be next to malaria as most serious health problems in developing tropical countries (Agunwa, 1988).

The global dimension of hypertension is immense, as it ranks the most common cardiovascular ailment afflicting about one billion people in the world and causing roughly 7.1 million deaths annually (Brundtland, 2002). Hypertension is said to be the most common cardiovascular disease among Africans and congestive cardiac failure its commonest complication (Akinkungbe 1972, 1985). Earlier studies suggested that hypertension was rare in African population (Sharper et al., 1969, Pobeeet al., 1977), however, epidemiological transition, urbanization, adoption of urban and foreign lifestyles and improved case findings, among others, have made hypertension more prevalent as shown in some studies (Cooper et al., 1998). The last Nigerian National Non-communicable Disease Survey (NNCDS) conducted in 1997 reported 11.4% prevalence of adult hypertension, varying from 14.8% in urban to 9.8% in rural residences respectively. However, a report on Nigeria from the World