TITLE PAGE ANTI-MALARIAL ACTIVITY AND PHARMACOKINETIC PROFILES OF METHANOL EXTRACT OF Strophanthus hispidus LEAVES A PROJECT REPORT SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF DOCTOR OF PHILOSOPHY (Ph.D) IN BIOCHEMISTRY (PHARMACOLOGY) BY UKEGBU, CHIMERE YOUNG PG/Ph.D/14/76645 DEPARTMENT OF BIOCHEMISTRY UNIVERSITY OF NIGERIA NSUKKA SUPERVISORS: DR. PARKER E. JOSHUA PROF O.F.C NWODO NOVEMBER, 2018 i CERTIFICATION Ukegbu, Chimere Young, a postgraduate student of the Department of Biochemistry, Faculty of Biological sciences, University of Nigeria, Nsukka with Registration Number PG/Ph.D/14/76645 has satisfactorily completed the requirements for the research work for the degree of Doctor of Philosophy (Ph.D) in Pharmacological Biochemistry. The work embodied in this report is original and has not been submitted, in part or full, for any other diploma or degree of this or any other University. ---------------------------------------- ---------------------------------------- Dr. P. E. Joshua Prof. O. F. C. Nwodo (Project supervisor) (Project supervisor) ---------------------------------------- -------------------------------------- Prof. F. C. Chilaka External examiner (Head of Department) ii DEDICATION This research work is dedicated to God-Almighty, the father of my lord Jesus Christ, the Source of my strength, inspiration and wisdom. iii ACKNOWLEDGEMENTS I wish to express my profound gratitude to the Almighty-God who has blessed me and brought me thus far. I sincerely appreciate my Supervisors, Prof. OFC Nwodo and Dr. Parker E. Joshua, whose love for excellence and speed spurred me into action. I am convinced to say that you are more than academic Supervisors. You are role models! I also wish to thank the lecturers in the Department of Biochemistry for their dedication and selflessness in discharging their duties. First I want to thank the Head, Prof F. C. Chilaka and to mention just a few, Prof. L. U. S. Ezeanyika, Prof. I. N. E. Onwurah, Prof. F. C. Chilaka, Prof. O. U. Njoku, Prof. S. O. O. Eze, Prof. H. A. Onwubiko, Prof. B. C. Nwanguma, Dr. V. N. Ogugua, Dr. C. S. Ubani, Dr. (Mrs.) C. A. Anosike and Dr (Mrs) U. O. Njoku, for their constructive criticism during my seminar presentations which helped to validate the scientific content of my research work. I deeply appreciate my family whose support has been matchless. Worthy of mention is my father, Mr. Ukegbu, Chinyere Young, who believed in me and kept on telling me “you will go places, you have the qualities to stand anywhere in the world and lead any group in the world”; my sweet and hardworking mother, Mrs. Ukegbu, Hellen who has sacrificed a lot to ensure that my dreams are fulfilled; my only brother, Ukegbu Uzoukwu is greatly appreciated for always being there for me and my sisters, Nkechi, Ugoma, and Precious Oluebube is also thanked for their numerous calls to know the progress of my studies. I will not forget to express my profound gratitude to the chief laboratory scientist at Department of Pharmacognosy, Faculty of Science, Amadu Bello University (ABU) Zaria, Mallam Ibrahim Kaibiru for his contribution to this research work and other post-graduate students who worked with me in the laboratory, just to mention a few, Atinga, Garuba and Emmanuel. Special thanks to natural product laboratories, Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS), University of Strathclyde, Glascow, United Kingdom for the 1H NMR and 13C NMR spectra analysis. I wish to appreciate Mr Nathaniel Friday who accommodated me in all my stay at Zaria without any cost and every member of Post-graduate Students’ Fellowship, Zaria and also members of Agape Choir Chapel of Redemption ABU Zaria. I also wish to appreciate the kind gesture of Mr Lanre Durojaiye and Mr Tobechukwu Paul Okoli who laboured in the in silico pharmacokinetics study and reference formatting respectively. Also worthy of note is the morale support and scientific judgement at different phases of this research work by my colleagues, Mr Abonyi Obiora, Casmir Ezeagu and Solomon Odiba. The happy moments I shared with the following people also provided the needed energy to endure till the end. They include my friends iv – Okechukwu Iroha, Onosakponome, Nwambam Ernest, Precious Chris ; my roommates past and present; Tosin, Irrenonsen, Samplus, Don, Wilson, Paul, Papa Bello, Bishop, Mamud, Bro Mike, Cyrill, Tony and Maxwel. Finally My choir members both in fellowship and church (Christ Church Chapel, Franco Outreach) just to mention a few; Victor, Joseph, Miracle, Nene, Chidinma, Ogechi, Prisca, Joy, Nkwachukwu, Ese, Jibrin, Faith, and my brethren at Graduate Students’ Fellowship. My spiritual fathers at home and in school here are not forgotten Rev. Uche, Rev. Prince, Rev. Prof. Christopher okeke, Pst. Don and members of Assemblies of God Church No. 1 Riverlayout Aba. To you all I say a big “thank you” for your love, companionship and prayers. v ABSTRACT Strophantus hispidus is a plant known to be used locally in the treatment of several diseases including malaria. Currently, there is sperse scientific reports found on the anti-malarial activity and bioactive compounds of the plant leaves. Thus the aim of the study was to investigate the anti- malarial properties of the methanol extract of Strophanthus hispidus (MESH) leaves and the possible elucidation of the bioactive compound(s). The percentage yield of the methanol extract of Strophanthus hispidus leaves obtained was 12.53%. The phytochemical compositions of the plant extract showed the presence of bioactive organic compounds such as alkaloids, flavonoids, terpenoids, steroids, phenols, saponins, tannins, soluble carbohydrates, reducing sugars and glycosides. The LD50 of the extract in mice was found to be above 5000 mg/kg b.w. Antimalarial activity of the crude extract of Strophanthus hispidus leaves showed that the extract was effective at various doses of 200, 400 and 800 mg/kg b.w. and showed a dose-dependent significant (p < 0.05) reduction in the parasitemia count of all the treatment groups when compared to the positive (untreated) control group. The P.berghei infected mice treated with various doses of the extract showed a significantly (p < 0.05) higher packed cell volume, red blood cell count and haemoglobin concentration compared to the positive control group. Conversely the packed cell volume, red blood cell count and haemoglobin concentration of the treatment groups showed significant (p < 0.05) decrease when compared to the negative control group. The mice treated with various doses of the extract showed significant (p < 0.05) reduction in the activities of liver marker enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) compared to the positive control group. Partitioning of the extract with different solvents gave the following percentage yields: n-Hexane (22%), dichloromethane (20%) and ethyl acetate (35.38%). Treatment with various doses (400 and 800 mg/kg b.w) of the fractions showed a dose dependent significant (p < 0.05) reduction in the parasitemia count of all the groups when compared to the untreated group. The P. berghei-infected mice treated with various doses of the fractions showed significantly (p < 0.05) higher packed cell volume, red blood cell count and haemoglobin concentration compared to the positive control group. The mice treated with various doses of the fractions showed significant (p < 0.05) reduction in the activities of liver marker enzymes (ALT, AST and ALP) compared to the positive control group. The animals treated with the n-Hexane fraction showed a non-significant difference (p > 0.05) in the AST and ALP activities when compared to the Negative control. Activities of some antioxidant enzymes such as superoxide dismutase (SOD) and catalase activity were found to be significantly (p < 0.05) higher in the groups treated with the fractions when compared to the positive control. There was a significant (p < 0.05) reduction in the formation of hemozoin in the groups treated with the non- polar fractions when compared to the positive control group. However comparatively the non- polar fractions were more effective than the polar fraction with n-Hexane fraction being the most active fraction. The calculated LC50 of the S. hispidus n-hexane fraction was found to be 245.5 µg/ml using Brine shrimp lethality Assay. Ninety-five fractions were obtained from column chromatography and combined based on their TLC profiles to give 9 fractions. The 9 fractions showed various levels of potency by inhibiting β-hematin synthesis. However, fractions 7-9 were the most potent fractions with percentage inhibition of 93%. Beta-setosterol-d-glucoside a steroid was identified as the active compound using 1H NMR, 13C NMR and IR spectra. ADME based on the Lipinski’s rule of 5 analysis revealed molecular weight (MW) of 576.86, hydrogen bond acceptor (HBA) of 6.0, hydrogen bond donor (HBD) of 4.0 and logP o/w 5.51. Beta-setosterol-d- glucose as the most active compound could take a lead in the discovery of new anti-malarial agent or used in combination therapy with artemisinin (ACT). vi TABLE OF CONTENTS Title Page i Certification ii Dedication iii Acknowledgements iv Abstract vi Table of Contents vii List of Figures xiv List of Tables xvii CHAPTER ONE: INTRODUCTION 1 1.1 Strophanthus hispidus 2 1.1.1 General Description of Strophanthus hispidus 2 1.1.2 Taxonomy of Strophanthus hispidus 4 1.1.3 Pharmacological/ Medicinal Importance of Strophantus hispidus 4 1.2 Phytochemicals 5 1.2.1 Alkaloids 5 1.2.2 Phenols 6 1.2.3 Flavonoids 7 1.2.4 Tannins 8 1.2.5 Terpenoids 8 1.2.6 Steroids 9 1.2.7 Saponins 9 1.2.8 Glycosides 10 vii 1.3 Malaria 11 1.3.1 Geographical Distribution and Populations at Risk 12 1.3.2 Causative Agents 13 1.3.3 Transmission and Biology of P.