IN VITRO PHARMACOLOGICAL PROPERTIES AND COMPOSITION OF LEAF ESSENTIAL OILS AND EXTRACTS OF SELECTED INDIGENOUS PELARGONIUM (GERANIACEAE) SPECIES Jacqueline Yolande Yvette Lalli A dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Pharmacy. Johannesburg, 2005. DECLARATION I, Jacqueline Yolande Yvette Lalli declare that this dissertation is my own work. It is being submitted for the degree of Master of Pharmacy at the University of the Witwatersrand, Johannesburg. It has not been submitted before for any degree or examination at this or any other University. Signature: ............................................ ........... day of .............................., 2006. ii DEDICATION To my parents Pier-Antonio and Patrizia Lalli. For all the sacrifices you have made in life, I hope this work can be a token of my deep appreciation. ‘You must understand the whole of life, not just one little part of it. That is why you must read, that is why you must look at the skies, that is why you must sing and dance, and write poems, and suffer, and understand, for all that is life.’ J. Krishnamurti iii PRESENTATION Jacqueline Y. Lalli, Alvaro M. Viljoen, Sandy F. van Vuuren, Hüsnü C. Başer. 2004. Aromatic Pelargoniums – their Essential Oils and Pharmacological Properties. Podium presentation at the Botany Symposium, University of Johannesburg, South Africa (Abstract, see Appendix B). iv ABSTRACT Despite commercial interest and ethnobotanical data, the chemical composition and pharmacological activities of a number of indigenous Pelargonium species remain unexplored. Twenty-one Pelargonium species, from the section Pelargonium, were included in this study. The volatile compounds of 13 species were extracted by hydrodistillation and their chemical compositions determined by gas chromatography coupled to mass spectroscopy (GC-MS). The essential oil data was chemotaxonomically informative confirming taxonomic relationships between P. graveolens and P. radens; P. papilionaceum and P. vitifolium and between P. panduriforme and P. quercifolium. New chemical affinities were established among P. betulinum, P. hispidum and P. scabrum; P. capitatum (provenance WSBG), P. glutinosum and P. quercifolium (provenance SBG) and among P. graveolens, P. radens and P. tomentosum. The non-volatile compounds were extracted with acetone and the extracts were analysed using high performance liquid chromatography (HPLC). The representative flavonoid patterns of the Pelargonium species indicated that P. betulinum, P. capitatum, P. graveolens, P. hispidum, P. panduriforme and P. vitifolium have numerous similarities in their chemical profiles. Pelargonium scabrum and P. sublignosum share definite chemical patterns. The HPLC fingerprints of P. papilionaceum and P. vitifolium were chemically diverse. A microdilution bioassay was performed on the acetone extracts and the essential oils to assess their antimicrobial (both bacterial and fungal) potential. The essential oils and extracts were more selective for the Gram-positive test pathogens than for the Gram- negative bacterium. The crude extracts of P. glutinosum (provenance SBG), P. pseudoglutinosum, P. scabrum and P. sublignosum exhibited considerable antimicrobial activity against the Gram-positive bacteria (B. cereus and S. aureus) with P. pseudoglutinosum exerting the highest activity (MIC = 0.039 mg/ml). The essential oils showed reduced antimicrobial activity compared to the plant extracts. Using the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay, exceptional anti-oxidant activity was observed for the crude extracts of P. betulinum and P. crispum (IC50 values of 4.13 µg/ml and 4.49 µg/ml, respectively, compared to ascorbic acid, IC50 = 4.72 µg/ml). The essential oils of P. quercifolium showed the greatest inhibition of 5-lipoxygenase activity (IC50 = 33.24 µg/ml v - 38.67 µg/ml). The antimalarial activity of the non-volatile extracts was evaluated against the choloroquine-resistant Gambian FCR-3 strain of Plasmodium falciparum using the hypoxanthine incorporation assay. Pelargonium panduriforme (provenance SBG) exerted the greatest activity (IC50 = 1.34 ± 0.29 µg/ml). Other species possessing similarly potent antimalarial activity included P. citronellum (provenance NBG), P. citronellum (provenance SBG), P. quercifolium (provenance SBG) and P. radens. A microculture tetrazolium salt reduction (MTT) assay was used to determine the cellular toxicity of the acetone extracts and essential oils against transformed human kidney epithelium (Graham) cells. The acetone extracts of P. sublignosum and P. citronellum (provenance NBG) displayed the highest toxicities (IC50 = 11.89 ± 1.54 µg/ml and 19.14 ± 0.98 µg/ml, respectively). Pelargonium vitifolium (IC50 = 178.48 ± 5.44 µg/ml) and P. tomentosum (provenance SBG) (IC50 = 195.13 ± 7.90 µg/ml) appeared to be non-toxic. The Pelargonium essential oils proved to be considerably toxic (IC50 ≤0.10 µg/ml - 30.30 ± 1.81 µg/ml). The flavonoid derivatives detected in the Pelargonium acetone extracts may have contributed to their positive biological activities. The results from the MTT assay suggested that the antimicrobial and antimalarial activity of the extracts may be ascribed to general cytotoxic effects. The pharmacological properties manifested by the extracts and essential oils of certain Pelargonium species substantiates their use in traditional medicines and validates their commercial exploitation in the perfumery, cosmetic, food and pharmaceutical industries; however, their toxicity profiles must be considered. vi ACKNOWLEDGEMENTS I would like to express my sincere gratitude to Professor Alvaro M. Viljoen. The dedication he showed throughout the research, gave me a lot of encouragement. I am very appreciative of the amount of knowledge I gained from him. I am also indebted to him for the photographs of the Pelargoniums. Acknowledgements to Ms Sandy F. van Vuuren. I appreciate her assistance in the antimicrobial work carried out. I am very grateful for the interest she showed and for her willingness to always help. A sincere thank you to Dr Robyn L. van Zyl who assisted me with the antimalarial assay and the toxicity testing. Her generous advice is acknowledged with appreciation. A special thank you to Professor K. Hüsnü C. Başer, Dr Betül Demirci and Dr Temel Özek at The Department of Pharmacognosy, Faculty of Pharmacy, Anadolu University, Eskişehir, Turkey. I appreciate their assistance in the GC-MS analysis of the essential oils. Their hospitality during my stay at the Anadolu University is greatly appreciated. Thank you to Dr Paul Steenkamp and Mr Nail Harding for their technical assistance in the HPLC analysis. I would like to thank Mr Andrew Hankey for allowing me to obtain plant material from the Walter Sisulu Botanical Garden (Johannesburg). Gratitude is expressed towards the staff of the National Botanical Garden (Kirstenbosch) and of the Stellenbosch Botanical Garden for allowing me to collect plant material for this study. Dr Brian M. Lawrence is thanked for his advice and comments on the reported essential oil compositions. Thank you to the National Research Foundation (Indigenous Knowledge Systems) for financial support. vii I greatly acknowledge the enduring tolerance and moral support shown by my parents. Special words of thanks to Maria Paraskeva for her unfailing encouragement, patience and understanding. I appreciate all her advice and support. I would like to express my gratitude to Yakov Frum for his generous help and patience. Thank you to my sister Chantal and Jean-Paul for their valuable help. I am sincerely grateful to Daniele, Francesca and Riccardo for all their advice and assistance in the last steps to completion of this research. Thank you to Deepti, Carla and Rupal for their support and inspiration. viii TABLE OF CONTENTS Page DECLARATION............................................................................................................. ii DEDICATION................................................................................................................. iii PRESENTATION........................................................................................................... iv ABSTRACT..................................................................................................................... v ACKNOWLEDGEMENTS............................................................................................ vii TABLE OF CONTENTS................................................................................................ ix LIST OF FIGURES........................................................................................................ xvi LIST OF TABLES.......................................................................................................... xix LIST OF ABBREVIATIONS, ACRONYMS AND SYMBOLS................................. xxi CHAPTER 1: GENERAL INTRODUCTION............................................................. 24 1.1 Plants provide therapeutic benefits............................................................................ 24 1.2 Drug development over the years.............................................................................. 25 1.2.1 From ‘Natural’ to synthetic.............................................................................. 25 1.2.2 Back to ‘Natural’.............................................................................................. 25