THE TOXICITY OF SENECIO INAEQUIDENS DC. by ALBERTO FRANCISCO PAULO DIMANDE Submitted in partial fulfillment of the requirements for the degree of Magister Scientiae in the Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria Date submitted: June 2007 TTTheThe Toxicity of Senecio inaequidens DC.DC.DC. ACKNOWLEDGEMENTS The author is indebted to all who made this project possible. Special thanks to: • The Swedish Agency for Research Cooperation with developing countries (SAREC) in Mozambique for the financial support; • My supervisors, Prof Christo Botha and Prof Leon Prozesky for their guidance, encouragement and support; • Dr Dries Lessing, the private practitioner, who notified us of the outbreak; • Miss Lizette Bekker and Mrs Magda Rösemann for assistance and technical support on the plant and biological sample extractions and chemical analyses; • Mrs Hannelie Snyman and Miss Elizabeth Retief for compiling the maps and providing the botanical description; • Mrs Leonie Labuschagne for assistance during the rat study and sheep dosing trial; • Mrs Elsbé Myburgh for the clinical chemistry analyses; • Mrs Michelle Kirsten for editing the dissertation; • All the people involved in this project and not mentioned here, my very special word of thanks. i TTTheThe Toxicity of Senecio inaequidens DC.DC.DC. ACKNOWLEDGEMENTS ............................................................................................. i SUMMARY ................................................................................................................... x CHAPTER 1 ................................................................................................................. 1 INTRODUCTION .......................................................................................................... 1 OBJECTIVES ............................................................................................................... 2 CHAPTER 2 ................................................................................................................. 3 LITERATURE REVIEW................................................................................................ 3 2.1 INTRODUCTION ............................................................................................... 3 2.2 DESCRIPTION AND IDENTIFICATION ............................................................ 5 2.2.1 General description............................................................................................ 5 2.2.2 Poisonous species of South Africa..................................................................... 6 2.2.3 Senecio inaequidens DC.................................................................................... 7 2.3 DISTRIBUTION OF POISONOUS SENECIO SPECIES IN SOUTHERN AFRICA ........................................................................................................... 10 2.3.1 Distribution of Senecio inaequidens DC........................................................... 10 2.4 POISONOUS PRINCIPLE(S) .......................................................................... 12 2.4.1 Chemical structure ........................................................................................... 12 2.4.2 Extraction and isolation.................................................................................... 13 2.4.3 Chemical analysis ............................................................................................ 15 2.5 OTHER PA CONTAINING PLANTS................................................................ 16 2.6 TOXICOKINETICS........................................................................................... 17 2.6.1 Absorption and distribution............................................................................... 17 2.6.2 Metabolism....................................................................................................... 18 2.6.3 Excretion .......................................................................................................... 21 2.7 MECHANISM OF ACTION .............................................................................. 22 2.7.1 Relationship between structure, metabolism and toxicity................................. 22 2.8 TOXICITY ........................................................................................................ 23 2.8.1 Acute hepatotoxicity......................................................................................... 24 2.8.2 Chronic hepatotoxicity...................................................................................... 24 2.8.3 Pneumotoxicity................................................................................................. 24 2.8.4 Other toxic effects ............................................................................................ 25 ii TTTheThe Toxicity of Senecio inaequidens DC.DC.DC. 2.9 SPECIES AFFECTED ..................................................................................... 27 2.9.1 Animals ............................................................................................................ 27 2.9.2 Humans............................................................................................................ 29 2.10 CLINICAL SIGNS IN LIVESTOCK .................................................................. 31 2.10.1 Acute toxicity.................................................................................................... 31 2.10.2 Chronic toxicity ................................................................................................ 32 2.11 CLINICAL PATHOLOGY................................................................................. 34 2.12 PATHOLOGY .................................................................................................. 35 2.12.1 Macroscopic lesions......................................................................................... 35 2.12.2 Histopathology ................................................................................................. 36 2.12.3 Electron Microscopy (EM)................................................................................ 37 2.13 DIAGNOSIS..................................................................................................... 38 2.14 DIFFERENTIAL DIAGNOSIS .......................................................................... 39 2.15 TREATMENT................................................................................................... 39 2.16 CONTROL AND/OR AVOIDANCE.................................................................. 39 CHAPTER 3 ............................................................................................................... 41 EXTRACTION OF PLANT MATERIAL AND ISOLATION OF PYRROLIZIDINE ALKALOIDS............................................................................................................... 41 3.1 INTRODUCTION ............................................................................................. 41 3.2 MATERIALS AND METHODS……………………………………………………. 41 3.2.1 Plant material ................................................................................................... 42 3.2.2 Sample preparation.......................................................................................... 43 3.2.3 Chemical extraction.......................................................................................... 43 3.2.4 Pyrrolizidine alkaloid analysis .......................................................................... 44 3.3 RESULTS ........................................................................................................ 45 3.4 DISCUSSION................................................................................................... 48 CHAPTER 4 ............................................................................................................... 51 CONFIRMATORY DOSING TRIALS ......................................................................... 51 4.1 PILOT STUDY ................................................................................................. 51 4.1.1 MATERIALS AND METHODS ......................................................................... 51 iii TTTheThe Toxicity of Senecio inaequidens DC.DC.DC. 4.1.2 RESULTS ........................................................................................................ 53 4.1.3 DISCUSSION................................................................................................... 63 4.2 SHEEP DOSING TRIAL .................................................................................. 68 4.2.1 MATERIALS AND METHODS ......................................................................... 68 4.2.2 RESULTS ........................................................................................................ 69 4.2.3 DISCUSSION................................................................................................... 74 CHAPTER 5 ............................................................................................................... 77 GENERAL DISCUSSION AND CONCLUSIONS....................................................... 77 CHAPTER 6 ............................................................................................................... 80 REFERENCES ........................................................................................................... 80 iv TTTheThe Toxicity of Senecio inaequidens DC.DC.DC. 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