ABSTRACT

Euporbia hirta, Breynia nivosa, Euphorbia heterophylla and Manihot esculenta powdered plant material were extracted using two solvents, ethanol and water. The ethanol extracts provided the higher yield and also more antimicrobial effectiveness than aqueous extracts. Phytochemical screening of the crude extracts revealed the presence of alkaloids, saponin, tannins, flavonoids, phenols and hydrogen cyanide (HCN). The plant extracts had a high percentage of HCN ranging from 13.48±0.03 to 39.15±0.04%. The presence of these bioactive constituents have been linked to the antimicrobial activity of the plant materials. The disc diffusion method was used to determine the antimicrobial activity against Pseudomonas aeruginosa, Enterobacter aerogenes, Salmonella pullorum and Proteus vulgaris.Minimum inhibitory concentrations was analysed using agar well diffusion method with values ranging from 50 to 200mg/ml. The growth of all the bacteria were inhibited through to varying degrees, thus justifying the use of the herbs in traditional medicine in treating enteric infections. P. vulgaris and P. aeruginosa were more susceptible with diameters ranging from 19mm and 16.33mm respectively. The antimicrobial activity of the plant materials is enhanced under acidic conditions and at elevated temperatures. The herbs E. hirta, B. nivosa, E. heterophylla and M. esculenta can be used as sources of oral drugs to fight infections caused by susceptible bacteria.

TABLE OF CONTENTS

Cover page

Title page i

Declaration ii

Certification iii

Dedication iv

Acknowledgement v

Table of content vi

List of tables viii

List of plates ix

Abstract x

CHAPTER ONE

INTRODUCTION 1

1.1 Aim and Objectives 2

1.2 Justification 3

1.3 Botany of the plants 3

1.3.1 Botany of Manihot esculenta Crantz (Cassava) 3

1.3.2 Botany of Breynia nivosa W. Bull(Small-Snow bush) 4

1.3.3 Botany of Euphorbia hirta Linn (Asthma plant) 5

1.3.4 Botany of Euphorbia heterophylla Linn (Purge weed) 6

CHAPTER TWO

2.1 Literature review 7

2.1.1 Phytochemical screening of plants 7

CHAPTER THREE

3.0 Materials and methods 10

3.1 Collection of plant materials and identification 10

3.1.1 Preparation of the samples for analysis 10

3.2 Phytochemical analysis 11

3.2.1 Qualitative analysis on leaf extract 11

3.1.1. Test for the presence of tannins 11

3.2.1.2 Test for the presence of saponins 11

3.2.1.3 Test for flavonoids 12

3.2.1.4 Test for the presence of Alkaloids 12

3.2.1.5Test for the presence of phenols 13

3.3 Quantitative analysis of phytochemicals 13

3.3.1 Determination of tannins 13

3.3.2 Determination of alkaloids 14

3.3.3 Determination of phenols 15

3.3.4 Determination of flavonoids 16

3.3.5 Determination of saponin 17

3.3.6 Determination of hydrogen cyanide (HCN) 18

3.4 Determination of antimicrobial activity 19

3.4.1 Production of plant extracts 19

3.4.2 Source of test organisms 20

3.4.4 Determination of minimum inhibitory concentration 21

3.4.5 Statistical Analysis 22

CHAPTER FOUR

4.0 Results 26

4.1 Phytochemical properties 26

4.1.1 Quantitative analysis 26

4.1.2 Qualitative analysis 27

4.1.3 Antimicrobial activity 29

4.1.4 Minimum inhibition concentration (MIC) 30

CHAPTER FIVE

5.0 Discussion and conclusion 37

5.1 Discussion 38

5.2 Conclusion 43

References