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5.1 INTRODUCTION CHAPTER 5 PHYTOCHEMICAL SCREENING Secondary metabolites are organic compounds that are not directly involved in the normal growth, development or reproduction of organisms. Unlike the absence of primary metabolites, the absence of secondary metabolities results not in immediate death, but in long-term impairment of the organism's survivability, or perhaps not in any significant change at all. Secondary metabolites are often restricted to a narrow set of species within a phylogenetic group. The function or importance of these compounds to the organism is usually of an ecological nature as they are used as defenses against predators, parasites and diseases; they are also used for interspecies competition, and to facilitate the reproductive processes (coloring agents, attractive smells, etc). Since these compounds are usually restricted to a much more limited group of organisms, they have long been of prime importance in taxonomic research (Mojab et al., 2003). Phytochemical techniques are developing fast and there are now tools available which allow for the analysis of complex mixtures in novel ways. Traditional medicines offer a rich and largely unexplored source of therapeutic leads for the pharmaceutical industry (Carson & Crews, 2007). Presently, numerous products derived from medicinal plants are used which offer many opportunities in the context of drug discovery (Cragg & Newman, 2005; Carson & Crews, 2007; Raskin et al., 2002). Phytochemical aspects of such drugs, by reason of being a rapidly emerging field of research, deserve special attention. For example, plant extracts containing a variety of bioactive compounds may provide important combination therapies that simultaneously affect multiple pharmacological targets and provide clinical efficacy beyond the reach of single compound-based drugs (Schmidt et al., 2007; Williamson, 2001). However, this clearly requires a clear and well-defined strategy to characterize such extracts and the plants they are derived from phytochemically. 85
5.2 SECONDARY METABOLITES 5.2.1 Alkaloids Alkaloids are naturally occurring chemical compounds containing basic nitrogen atoms. Their name was derived from the word alkaline and was used to describe any nitrogen-containing base. Alkaloids are produced by a large variety of organisms including bacteria, fungi, plants, and animals. Many alkaloids are toxic and often have a pharmacological effect, which makes them to be used as medications and recreational drugs. Some alkaloids have a bitter taste (Filippos et al., 2007). 5.2.2 Flavonoids Flavonoids are derived from 2-phenylchromen-4-one (2-phenyl-1-4-benzopyrone). They are commonly known for their antioxidant activities. Flavonoids, which are widely distributed in plants, fulfil many functions including producing yellow, red or blue pigmentation in flowers and protection from attacks by microbes and insects. Compared to other active plant compounds, they are low in toxicity. Flavonoids are referred to as nature’s biological response modifiers because of strong experimental evidence of their inherent ability to modify the body’s reaction to allergens, viruses and carcinogens. They show anti-allergic, anti-inflammatory, antimicrobial and anticancer activity (Filippos et al., 2007). 5.2.3 Saponins Saponins are the glycosides of 27 carbon atom steroids, or 30 carbon atom triterpenes in plants. They are found in various plant parts: leaves, stems, roots, bulbs, flowers and fruits. They are characterized by their bitter taste and their ability to haemolyze red blood cells. Saponins dissolve in water to form a stable soapy froth; this is thought to be due to their amphiphilic nature. They are highly toxic to cold-blooded animals, due to their ability to lower surface tension. Some saponins are poisonous. They can cause skin rash in many people if swallowed. They are also used medically as expectorant, emetic and for the treatment of excessive salivation, epilepsy, chlorosis and migraines. They are popular ingredients in shampoos and 86
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Antimicrobial activity testing of t
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3.1 Introduction 21 3.2 Plants used
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Appendix I: Research questionnaire
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2.5 Sensitivity table of MDR Gram p
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2n diploid Abbreviations ATCC Ameri
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Dedication My sincere thanks and gr
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CHAPTER 1 INTRODUCTION Plants have
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legislation in South Africa, which
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1.1 OBJECTIVES The objectives of th
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Table 2.1 Plants that were collecte
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Scientific names Zulu names Parts u
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Surname Gender Place Age-range M. D
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Antibiotics Escherichia coli U16403
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Dragendorff’s reagent Ethanol (Fe
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The plates were observed for the pr
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2.6.4 Anthraquinones Dried plant ma
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3.1 INTRODUCTION CHAPTER 3 ETHNOBOT
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3.2.1 Scientific name : Acanthosper
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Medicinal uses The Acorus calamus i
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Figure 3.5 The fruits of Albizia ad
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Botanical description Baccharoides
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Data from ethnobotanical survey The
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3.2.7 Scientific name : Hypoxis hem
Page 48 and 49: 3.2.8 Scientific name : Faurea sali
Page 50 and 51: emerge from the crown and bear a si
Page 52 and 53: Conservation status The species is
Page 54 and 55: 3.2.12 Scientific name : Lippia jav
Page 56 and 57: 3.2.13 Scientific name : Pentanisia
Page 58 and 59: Botanical description The marula is
Page 60 and 61: The lobed discolorous leaves, the m
Page 62 and 63: Figure 3.21 The leaves of Trichilia
Page 64 and 65: 3.2.17 Scientific name : Warburgia
Page 66 and 67: 3.2.18 Scientific name : Ziziphus m
Page 68 and 69: According to the interviews that we
Page 70 and 71: CHAPTER 4 ANTIMICROBIAL ACTIVITY 4.
Page 72 and 73: factor in selecting resistant micro
Page 74 and 75: present in a cow’s udder or equip
Page 76 and 77: haemolysins, leukocidin, and perhap
Page 78 and 79: 4.4.2 Disc diffusion results The di
Page 80 and 81: Table 4.15 Comparison of results ob
Page 82 and 83: PLANT NAMES Agar well result SA Dis
Page 86 and 87: PLANT NAMES Agar well result SA4790
Page 90 and 91: PLANT NAMES Agar well result ECU164
Page 92 and 93: The use of American Type Culture Co
Page 94 and 95: mentioned strain which were Acantho
Page 96 and 97: In this study it was found that Aco
Page 100 and 101: cleansers. They are used in Ayurved
Page 102 and 103: Plant species Alkaloids Flavonoids
Page 104 and 105: Trichilia dregeana in this study wh
Page 106 and 107: Rf =Distance moved by the compound/
Page 108 and 109: Figure 6.5 The TLC plate (left) and
Page 110 and 111: 6.3 DISCUSSION The bio-autoautograp
Page 112 and 113: the results obtained from the agar
Page 114 and 115: e at least effective as forest guar
Page 116 and 117: Brain, K.R., Turner T.D., 1975. The
Page 118 and 119: Howard, P.L., 2003. Women and Plant
Page 120 and 121: McGaw, L.J., Jager, A.K., van Stade
Page 122 and 123: Portillo, A., Vila, R., Freixa, B.,
Page 124 and 125: Van Vuuren, S., 2007. The antimicro
Page 126 and 127: APPENDIX I: Research Questionnaire
Page 128 and 129: ___________________________________
Page 130 and 131: APPENDIX II: Antimicrobial activity
Page 132 and 133: a + 2 Average Calculation of result
Page 134 and 135: Sensitivity of different bacteria a
Page 142 and 143: Table 4.7 Results of sensitivity of
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Sensitivity of different bacteria a
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MIC results in mg/ml ATTC CULTURES
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Table 4.12 Minimum inhibitory conce
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