ABSTRACT

The phytochemical composition, antimicrobial and antioxidant activities of leaf of Croton gratissimus (lavender croton) was studied. Extraction of the leaf were obtained in different solvents (water, ethanol and ethyl acetate) and test at invitro level against, Staphylococcus aureus, Escherichia coli and Candida albicans. Results of preliminary phytochemical screening shows the presence of many phytochemicals including alkaloids, saponins, flavonoid, Taninnis, steroids and cyanogic glucosides at varying levels of detection. Quantative analysis of the leaf showed varied concentrations of the phytochemicals such as alkaloids (0.82%), Flavonoid (1.02%), saponin (0.37%), Tannin (0.58%), Phenols (0.82%), phytate (0.33%) and HCN (6.70mg/kg). The antimicrobial tests result indicated varying levels of inhibition of the three microbial pathogens, (Staphylococcus aureus, Escherichia coli and Candida albicans) by the plant extracts in different solvents. Water extract caused inhibition of diameters 12.33mm, 14.33mm, and 14.33mm, against Staphylococcus aureus, Escherichia coli, Candida albicans respectively while that of ethanol extract were 19.00mm, 24.33mm and 15.67mm and ethyl acetate extract had 16.33mm, 14.33mm and 18.67mm for the same test organisms respectively. The activity of the extracts were lower than that of standard antibiotic, which recorded 24.33mm, 23.33mm and 25.67mm against the same organisms. Further antimicrobial tests show minimum inhibition concentrations (MIC) of 150mg/ml for the water extract against each of the organisms. while, the ethanol extract was active at 100mg/ml 50mg/ml and 100mg/ml against Staphylococcus aureus Escherichia coli and Candida albicans respectively. Concentration of phytochemicals with antioxidant potency in the leaf was 21.38 mg /100g Vitamin C, 1.02% Flavnoid and 0.82 % Phenolics. Results of the antioxidant activity showed scavenging activity of 53.03%, chelating activity of 40.08% and reducing activity of standard antioxidant, Butylated Hydro toluene (BHT). Potential health benefits of Croton gratissimus leaves were recognized.

TABLE OF CONTENTS

Title page i

Certification ii

Dedication iii

Acknowledgements iv

Table of contents v

List of tables xi

Abstract xii

CHAPTER ONE

1.1 Introduction 1

1.2 Main Aim and Objective of the Research 3

CHAPTER TWO

2.0 LITERATURE REVIEW 4

2.1 Description and Habitat of Croton gratissimus 6

2.2 Nomenclature of Croton gratissimus 6

2.3 Growing Croton gratissimus 7

2.4 UsesVApplications of Croton Species 7

2.5 Phytochemical composition of Croton 8

2.5.1 Biological activities of the important phytochemicals found in plant 9

2.6 Mechanism of Antimicrobial Action of Bioactive Components of Plants 14

2.7 Some Phytochemical Groups And Mechanism of Anti-Infective Action 15

2.8 Plant as Alternative source of Antimicrobials

2.8.1 Plants having activity against multi drug resistance 17

2.8.2 Prospective of plants having activity against multi drug resistance 18

CHAPTER THREE

MATERIALS AND METHOD 20

3.1 Materials 20

3.2 Methods 20

3.2.1 Sample and media preparation 20

3.2.2 Media preparation 20

3.3 Preparation of Leave Extracts 21

3.4 Determination of Phytochemicals Content of the Plant Sample 21

3.4.1 Test for presence of alkaloids 21

3.4.2 Test for the presence of flavonoid 22

3.4.3 Test for the presence of phenols 22

3.4.4 Test for the presence of saponin 22

3.4.5 Test for the presence of tannin 23

3.4.6 Test for the presence of cyanogen glycosides 23

3.4.7 Test for steroid 23

3.4.8 Test for starch 24

3.5 Quantitative Determination of Phytochemical Constituents of the Plant Samples 24

3.5.1 Determination of alkaloid 24

3.5.2 Determination of flavonoid 25

3.5.3 Determination of phenols 25

3.5.4 Determination of saponins 26

3.5.5 Determination of tannin 27

3.5.6 Determination of cyanide 27

3.5.7 Determination of phytate 28 

3.5.8 Determination of steroid 29

3.6. Preparation of Inoculant 30

3.6.1 Antimicrobial activity test 30

3.6.2 Minimum inhibitory concentration (mic) test 30

3.7. Determination of antioxidants 31

3.7.1 Determination of vitamin c 31

3.7.2 Chelating activity 31

3.7.3 Scavenging activity 32

3.7.4 Reducing activity 32

3.8 Statistical methods 33

CHAPTER FOUR

4.0 RESULTS 34 

CHAPTER FIVE

DISCUSSION, CONCLUSION AND RECOMMENDATIONS 40

5.1 Discussion 40

5.2 Conclusion 42

5.3 Recommendations 43

References

Appendix

LIST OF TABLES

Table Title Page 

1: Phytochemical Screening of Extract of Croton gratissimus 34

2: Qualitative phytochemical screening 35

3: Antimicrobial activity of Croton gratissimus extracts 36

4: Minimum Inhibitory Concentration, (mg/ml) of crude extracts of Croton gratissimus

against Staphylococcus aureus, Escherichia, coli and Candida albicans 37

5: Antioxidant components of leaf of Croton gratissimus 38

6: Antioxidant activity of Croton gratissimus 39