Table of Contents TABLE OF CONTENTS ............................................................................................................... i LIST OF FIGURES ..................................................................................................................... vii LIST OF TABLES ..................................................................................................................... xiii ACKNOWLEDGEMENT ......................................................................................................... xiv PREFACE ................................................................................................................................... xv SUMMARY ............................................................................................................................. xviii ABSTRACT ............................................................................................................................... xix Chapter 1 General Introduction 1.1 Background and motivation of the study ......................................................................... 2 1.2 Objectives of the study ...................................................................................................... 3 1.3 Structure of thesis .............................................................................................................. 4 1.4 References ......................................................................................................................... 6 Chapter 2 Acne: a review on epidemiology, pathogenesis and treatment options 2.1 Introduction ....................................................................................................................... 8 2.2 Cosmeceuticals .................................................................................................................. 9 2.3 Skin and acne .................................................................................................................... 9 2.4 Epidemiology .................................................................................................................. 11 2.5 Propionibacterium acnes, the causative agent ................................................................ 12 2.6 Pathogenesis of Propionibacterium acnes ..................................................................... 13 2.7 Immunology of acne ........................................................................................................ 14 2.8 Conventional drugs available for treating acne ............................................................... 15 2.9 Possible potential of plants for treating acne .................................................................. 17 2.10 References ....................................................................................................................... 19 Chapter 3 Plants selected for the present study 3.1 Introduction ..................................................................................................................... 23 3.2 Description of selected plants ......................................................................................... 24 i 3.2.1 Acacia caffra (Thunb.) Willd. ............................................................................. 24 3.2.2 Acacia galpinii Burtt Davy ................................................................................. 25 3.2.3 Acacia mellifera Benth. ....................................................................................... 26 3.2.4 Aloe arborescens Mill ......................................................................................... 27 3.2.5 Aloe barbadensis Mill ......................................................................................... 28 3.2.6 Aloe ferox Mill. ................................................................................................... 29 3.2.7 Aloe sessiliflora Pole-Evans. ............................................................................... 30 3.2.8 Anchusa capensis Thunb. .................................................................................... 31 3.2.9 Annona senegalensis Pers. .................................................................................. 32 3.2.10 Arbutus unedo L. ................................................................................................ 33 3.2.11 Aspalathus linearis R.Dahlgren .......................................................................... 34 3.2.12 Barleria albostellata C. B. Clarke ...................................................................... 35 3.2.13 Barleria repens Nees ........................................................................................... 36 3.2.14 Broussonetia papyrifera (L.) Vent. ..................................................................... 37 3.2.15 Buxus macowanii Oliv. ....................................................................................... 38 3.2.16 Carpobrotus edulis (L.) L. Bolus ........................................................................ 39 3.2.17 Ceratonia siliqua L. ............................................................................................ 40 3.2.18 Combretum apiculatum Sond. ............................................................................. 40 3.2.19 Combretum molle Engl. & Diels. ........................................................................ 41 3.2.20 Cotyledon orbiculata L. ...................................................................................... 42 3.2.21 Cryptocarya woodii Engl. ................................................................................... 44 3.2.22 Dahlia imperialis Roezl ...................................................................................... 44 3.2.23 Datura stramonium L. ......................................................................................... 45 3.2.24 Dichrostachys cinerea L. White & Arn. ............................................................. 46 3.2.25 Diospyros lycioides Desf. .................................................................................... 47 3.2.26 Dodonaea viscosa Jacq. ...................................................................................... 48 3.2.27 Erythrophleum lasianthum Corbishley .............................................................. 49 3.2.28 Euclea divinorum Hiern ..................................................................................... 50 3.2.29 Euclea natalensis A. DC. .................................................................................... 51 3.2.30 Galenia africana L.. ............................................................................................ 52 3.2.31 Gomphocarpus fruticosus R. Br. ......................................................................... 53 3.2.32 Greyia flanaganii Bolus ...................................................................................... 54 ii 3.2.33 Greyia sutherlandii Hook. & Harv. .................................................................... 55 3.2.34 Harpephyllum caffrum Bernh. ex Krauss. ........................................................... 56 3.2.35 Helichrysum argyrophyllum DC.. ....................................................................... 57 3.2.36 Helichrysum glomeratum Klatt. .......................................................................... 58 3.2.37 Heteropyxis natalensis Harv. .............................................................................. 59 3.2.38 Hyaenanche globosa Lamb. ................................................................................ 60 3.2.39 Knowltonia vesicatoria Sims. ............................................................................. 61 3.2.40 Leucosidea sericea Eckl. & Zeyh.. ..................................................................... 62 3.2.41 Magnolia grandiflora L. ..................................................................................... 63 3.2.42 Myrsine africana L. ............................................................................................. 64 3.2.43 Parinari curatellifolia Planch. ex Benth. ............................................................ 65 3.2.44 Ranunculus repens L.. ......................................................................................... 66 3.2.45 Rhus lancea L.f. .................................................................................................. 67 3.2.46 Sclerocarya birrea Hochst. ................................................................................. 68 3.2.47 Sideroxylon inerme L. ......................................................................................... 69 3.2.48 Symphytum officinale L. ..................................................................................... 70 3.2.49 Syzygium jambos (L.) Alston. ............................................................................. 71 3.2.50 Warburgia salutaris (G.Bertol.) Chiov. .............................................................. 72 3.2.51 Zanthoxylum capense Harv. ................................................................................ 73 3.3 References ....................................................................................................................... 82 Chapter 4 Antibacterial, antioxidant activities and cytotoxicity of plants against Propionibacterium acnes 4.1 Introduction ....................................................................................................................