PHOTOSENSITIZING THIOPHENES FROM THE "TAGETEAE by KELSEY DOWNUM B.S., Colorado State University, Fort Collins, Colorado, 1975 M.S., Colorado State University, Fort Collins, Colorado, 1978 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSHOPHY in THE FACULTY OF GRADUATE STUDIES (Department of Botany) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA 13 August 1981 c) Kelsey Downum, 1981 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date /Q C4^^,^T/9R/ i i ABSTRACT Two separate aspects involving the thiophenes of the Tageteae (Asteraceae) were investigated. The first concerned the distribution of four thiophenes in Tagetes patula L. which were examined by high pressure liquid chromatography (HPLC). The derivatives were found to be differentially distributed throughout hydroponically grown plants. The predominant thiophenes in roots were 5-(4-acetoxy-1-butenyl)-2,2'-bithienyl (BBT-OAc) and 5-(buten-3-ynyl)-2,2'-bithienyl (BBT). BBT-OAc was the main derivative in shoots, whereas 2,2':5',2''- terthienyl (alpha-T) was the major compound in flower petals. BBT and one unidentified compound were found to occur in leaf glands. The levels of BBT-OAc in shoots and BBT-OAc and BBT in roots increased over the life of the plant and reached a plateau following flowering. Alpha-T in roots and both alpha- T and BBT in shoots remained at low levels over the life of the plant while 5-(4-hydroxy-1-butenyl)-2,2'-bithienyl (BBT-OH) was found to be an minor component of roots or shoots. Fourteen species from four genera of the tribe Tageteae were also screened for the presence of thiophenes by HPLC. Representatives of Dyssodia, Porophyllum, and Tagetes all contained thiophenes, but none were detected in species of Pectis. The second part of this study concerned the photobiocidal effects of isolated thiophenes on Escherichia coli B which was used as a model biological system. Alpha-terthienyl (alpha- T), in the presence of UV-A irradiation (320nm-400nm), was found to be a Type II photosensitizer which required oxygen for the expression of biological activity. Scavenger studies with sodium azide and BHT suggested that both singlet oxygen and superoxide were generated by the photosensitized reaction. Cellular inactivation by alpha-T was sensitive to temperature and studies with recombination deficient mutants of E. coli K- 12 did not indicate that damage to cellular DNA occurred. Proteins were found to be substantially affected by the photoactivated reaction. SDS-gel electrophoresis revealed that both cytoplasmic and membrane-associated proteins might be. crosslinked following treatment with alpha-T and UV-A. iv TABLE OF CONTENTS ABSTRACT 1 LIST OF TABLES 1 LIST OF FIGURES ! ACKNOWLEDGEMENTS 1 PREFACE 1 SECTION I. PHYTOCHEMICAL ASPECTS OF THIOPHENES 2 INTRODUCTION ; .---3 MATERIALS AND METHODS 9 Chemicals 9 Plant Material 10 Dried Plant Specimens 10 Hydroponics 11 Extraction of Thiophenes 12 Identification of Thiophenes 13 Chromatography 14 TLC 14 Column Chromatography . 16 High Pressure Liquid Chromatography 16 Qualitative HPLC Studies 17 Quantitative HPLC Studies 17 Phototoxicity of Thiophene Standards 19 RESULTS AND DISCUSSION ' 19 Structural Verification of Standards 21 Chromatography 21 Qualitative Analysis of Thiophenes 25 Quantification of Thiophenes 29 Distribution of Thiophenes in the Tageteae 38 Biological Activity of Thiophene Standards 41 CONCLUSION 42 SECTION II. PHOTOBIOLOGICAL ASPECTS OF THIOPHENES 44 INTRODUCTION 45 MATERIALS AND METHODS 50 Irradiation Sources 50 Survival Curves 51 Bacterial Preparation 54 Assay Procedure 54 Alpha-Terthienyl Action Spectrum 55 Rec Mutant Assay 57 Scavenger Studies 57 Temperature Studies 58 Crosslinking of E. coli Proteins 59 SDS-Polyacrylamide Gel Electrophoresis 60 RESULTS AND DISCUSSION 61 Survival Curves 61 Action Spectrum 65 Studies on Repair Deficient Mutants of E. coli 67 Aerobic-Anaerobic Studies 69 Effect of Scavengers on Alpha-T Phototoxicity 74 Temperature Studies 78 Effects of Alpha-T on Cellular Proteins 84 CONCLUSION 88' vi APPENDIX I 90 LITERATURE CITED 92 vii LIST OF TABLES Table 1. Occurrence of thiophenes in the Asteraceae 5 Table 2. Composition of hydroponic growth medium 12 Table 3. Thin layer chromatographic data of the thiophenes. 23 Table 4. High pressure liquid chromatographic data of thiophene derivatives 24 Table 5. Thiophene concentrations in crude T. patula extracts 36 Table 6. Distribution of thiophenes within the tribe Tageteae 39 Table 7. Phototoxicity of thiophenes to microorganisms ... 41 Table 8. Dosimetric parameters used to determine the action spectrum of alpha-T 53 Table 9. Strains of E. coli K-12 mutants and their relevant characteristics 58 Table 10. Response of various E. coli rec mutants to alpha-T, BBT, bleomycin and 8-MOP 68 t viia LIST OF FIGURES Figure 1. The thiophenes isolated and identified from Tagetes patula L 4 Figure 2. A proposed biosynthetic pathway for the formation of thiophenes from the precursor, the "penta- yne-ene" 6 Figure 3. Chemical structures of the thiophenes used in these studies 20 Figure 4. HPLC trace of the UV absorbing components from the roots of 8 week old hydroponically grown T. patula. 26 Figure 5. HPLC trace of the UV absorbing components from the shoots of 8 week old hydroponically grown T. patula. 27 Figure 7. HPLC trace of the UV absorbing components from the leaf glands of 8 week old hydroponically grown T. patula 27 Figure 6. HPLC trace of the UV absorbing components from flowers of 8 week old hydroponically grown T. patula. 28 Figure 8. HPLC standard concentration curve for BBT-OH (VII) 31 Figure 9. HPLC standard concentration curve for BBT-OAc (VIII) 32 Figure 10. HPLC standard concentration curve for BBT (IX). Figure 11. HPLC standard concentration curve for alpha-T (X) . .. 34 Figure 12. The accumulation of thiophenes in roots over the life of hydroponically grown T. patula 35 Figure 13. The accumulation of thiophenes in shoots over the life of hydroponically grown T. patula 37 Figure 14. Irradiance (mW/cm2) versus wavelength for the fluorescent sources used in these studies 52 Figure 15. Survival curves of E. coli in response to various doses of alpha-T and UV-A irradiation 62 Figure 16. Survival curves of E. coli in response to various doses of BBT and UV-A irradiation 64 Figure 17. Action spectrum of the bactericidal activity of alpha-T versus the absorption for alpha-T between 320nm and 400nm 66 Figure 18. Response of E. coli B to alpha-T and UV-A irradiation under aerobic conditions 71 Figure 19. Response of E. coli B to alpha-T and UV-A irradiation under anaerobic conditions 72 Figure 20. Response of Pseudomonas aeruginosa to alpha-T and UV-A irradiation under aerobic and anaerobic conditions 73 Figure 21. Survival of E. coli B in the presence of alpha- T and UV-A irradiation with 20 mM sodium azide 75 Figure 22. Survival of E. coli B in the presence of alpha- T and UV-A irradiation with 50 uM BHT 77 Figure 23. Survival of E. coli B in the presence of alpha- X T and UV-A irradiation with 20 mM sodium azide and 50 uM BHT 79 Figure 24. Survival of E. coli B in the presence of alpha- T and UV-A irradiation at various irradiation temperatures .. 80 Figure 25. Arrhenius plot of the data presented in Figure 24 82 Figure 26. The effect of incubation temperature on the survival of E. coli in the presence of alpha-T and UV-A irradiation 85 Figure 27. SDS-gel electropherogram of the proteins of E. coli B following treatment with alpha-T and UV-A irradiation. 86 xi ACKNOWLEDGEMENTS I wish to thank the members of my research committee, Drs. A.D.M. Glass, P.J. Harrison, R.E.W. Hancock and G.H.N. Towers for their helpful suggestions throughout my research and for their careful reading and criticism of this manuscript. Special thanks, to Dr. R.E.W. Hancock for his generous assistance, guidance, interest, and enthusiasm and to the people of his laboratory whose kind help, acceptance, and understanding made my work there enjoyable. I am especially grateful—to-—Dr. G.H.N. Towers for my introduction into the field of photobiology and for his advice, encouragement, and continued support over my time in his laboratory. I would also like to thank Drs. T. Arnason, E. Camm, F. Garcia, M. Tepfer, and R. Suetfeld for many helpful suggestions and discussions and Drs. Garcia and Suetfeld for providing reference compounds. Thanks to Ms. Z. Abramowski and Ms. E.A. Graham for technical assistance and to Dr. David Zittin in the Biosciences Data Center for assistance in preparing this manuscript. I could never say enough about the patience, understanding and support which my wife, Julie, has offered through it all. Thank you. 1 PREFACE Plants produce many diverse chemical constituents which elicit interesting biological activities in isolated or purified form. The thiophenes are one such group of compounds synthesized by members of the plant family Asteraceae and are characteristic of the tribe Tageteae. These derivatives are toxic toward a wide variety of biological organisms when excited .by longwave ultraviolet (UV-A) irradiation.