13 research outputs found

    Chemical and biological investigation into some selected African indigenous medicinal plants

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    Philosophiae Doctor - PhDAfrican medicinal plants are commonly used throughout Africa to treat a variety of ailments including wounds and ulcers, cough and chest complaints, gingivitis, fever and gonorrhoea, indication all related to infection and inflammation. In screening several plant species from an inventory of common medicinal plants from both South and West Africa for diverse medicinal purposes, 6 plants were selected because of their interesting and useful ethnomedicinal values.South Afric

    Southern African plants used to treat central nervous system related disorders.

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    Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.The majority of the population in South Africa use traditional health care to treat various mental conditions. This thesis has two main objectives; to bring together a comprehensive and detailed record of psychotropic plants used in southern Africa by indigenous peoples for medicinal or cultural purposes. Secondly, this research attempts to investigate the validity and rationale of the use of these plants by screening them in various biological assays for psychotropic activity. Plants were selected, based on their traditional use and availability, and were screened in four assays, which detect biological activity of a useful nature. A number of in vitro enzymatic and neuronal signal transduction assays were employed in this thesis, the inhibition of the serotonin reuptake transporter protein (SERT); inhibition of catabolic enzymes (e.g. acetylcholinesterase, monoamine oxidase); GABAA- benzodiazepine receptor binding. The influence of legislation, past and present, on the state of traditional medicine is highlighted. Aspects of the philosophies and practises of the various practitioners of South African traditional medicine will be discussed. An annotated list compiled from available ethnobotanical literature of plants traditionally used for central nervous system-related purposes is provided. It contains more than 330 species, from 94 families, which are currently used or have been used for cultural, medicinal and recreational purposes related to the central nervous system (CNS). Where available, information pertaining to plant part used, preparation method, dosage, route of administration, known and potentially active constituents are included. Seventy five extracts from 34 indigenous plant species used in South African traditional medicine or taxonomically related to these were investigated for their affinity to the serotonin reuptake transport protein, making use of an in vitro [3H]-citalopram serotonin reuptake transport protein binding assay. Aqueous and 70% ethanolic extracts of various plant parts were screened and 45 extracts derived from 15 plant species showed affinity. The affinity of 12 extracts from four plants was characterized as high (more than 50% inhibition at 5, 1, and 0.5 mg/ml). Plant species with high affinity to the serotonin reuptake transport protein included Agapanthus campanulatus, Boophone disticha, Datura ferox and Xysmalobium undulatum. Agapanthus campanulatus yielded high activity in aqueous extracts from leaves and flowers. B. disticha showed high activity both in aqueous and ethanolic extracts of leaves and bulbs. D. ferox showed high activity in aqueous extracts from the seeds and X. undulatum showed high activity in the ethanolic extract of the whole plant. Two compounds, buphanadrine and buphanamine, were isolated by bioassay-guided fractionation on vacuum-liquid-chromatography (VLC) and preparative thin-layer-chromatography (TLC) from B. disticha. The structures of the compounds were determined by 1H and 13C NMR. Fractions were tested for affinity to the serotonin transporter in a binding assay using [3H]-citalopram as a ligand. The IC50 values of buphanidrine and buphanamine were 274 ìM (Ki = 132 ìM) and 1799 ìM (Ki = 868 ìM), respectively. The two alkaloids were also tested for affinity to the 5HT1A receptor, but only showed slight affinity. Aqueous and ethanol extracts of 43 plants that are traditionally used to treat against epilepsy and convulsions were initially tested in the GABAA-benzodiazepine receptor binding assay, where the binding of 3H-Ro 15-1788 (flumazenil) to the benzodiazepine site is measured. The GABAA-benzodiazepine receptor complex is involved in epilepsy and convulsions. Out of the 118 extracts tested, one aqueous and 18 ethanol extracts showed activity. The most active extracts were the ethanolic leaf extracts of Searsia tridentata, Searsia rehmanniana and Hoslundia opposita and the ethanolic corm extract of Hypoxis colchicifolia, which all showed good dose-dependent activity. A further forty-six ethanol extracts from another 35 species, both indigenous and exotic that are traditionally used predominantly as sedatives or to treat various CNS-related ailments were tested in the GABAA-benzodiazepine receptor-binding assay. Out of the 46 extracts tested, seven showed good activity and 10 showed moderate activity. The most active extracts were the ethanolic leaf extracts of Arctopus echinatus, Artemisa afra, four Helichrysum species and Mentha aquatica which all showed good dose-dependent activity. Two biflavonoids with activity in the 3H-Ro 15-1788 (flumazenil) binding assay were isolated by high pressure liquid chromatography (HPLC) fractionation of the ethanol extract of the leaves from Searsia pyroides. The structures of the two biflavonoids were elucidated by nuclear magnetic resonance spectroscopy (NMR) to be agathisflavone and amentoflavone. Agathisflavone and amentoflavone competitively inhibited the binding of 3H-Ro 15-1788 with a Ki of 28 and 37 nM, respectively. Extracts of Searsia dentata and Searsia pentheri were not as active as the extract from Searsia pyroides; both were found to contain apigenin and agathisflavone. The monomer apigenin, agathisflavone and amentoflavone were fitted into a pharmacophore model for ligands binding to the GABAA receptor benzodiazepine site. This reflected the affinities of the compounds in the [3H]-flumazenil binding assay. Mentha aquatica, a mint that is found in Europe and Africa, is used in Zulu traditional medicine for spiritual purposes. The ethanolic leaf extract showed a strong affinity to the GABA-benzodiazepine receptor. Viridiflorol from the essential oil and (S)-naringenin from an ethanolic extract was isolated by bioassay-guided fractionation using binding to the GABA-benzodiazepine site. Viridiflorol had an IC50 of 0.19 M and (S)-naringenin of 0.0026 M. Twenty plants used in Zulu traditional medicine for several CNS-related ailments were screened for MAO inhibition and specific MAO-B inhibition activity. MAO-B inhibitors are currently employed in the treatment of neurodegenerative related illnesses such as Parkinson's and Alzheimer's diseases. A photometric peroxidase linked assay was used to determine the inhibition of the oxidative deamination of tyramine by MAO isolated from rat liver. Ruta graveolens exhibited the best MAO inhibitory activity (ethyl acetate leaf extract = IC50 5 ± 1 ìg/ml, petroleum ether extract = 3 ± 1 ìg/ml) and specific MAO-B inhibition (ethyl acetate leaf extract = IC50 7 ± 6 ìg/ml petroleum ether extract = 3 ± 1 ìg/ml). Schotia brachypetala, Mentha aquatica and Gasteria croucheri also exhibited good MAO-B inhibition activity. Six extracts of varying polarity of Mentha aquatica were tested in a photometric peroxidase linked MAO bioassay. The 70% ethanol extract had highest inhibitory activity. (S)-Naringenin was isolated from the extract by bioassay guided fractionation on VLC and preparative TLC. The structure of the compound was determined by 1H, 13C and 13C-DEPT NMR and optical rotation. The IC50 values for MAO inhibition by naringenin were 342 ± 33 ìM for the rat liver mitochondrial fraction, 955 ± 129 ìM for MAO-A and 288 ± 18 ìM for MAO-B respectively. South African traditional medicine clearly utilizes many botanical species with CNS-related activity. Only a small number of the more than 330 southern African plant species reported to treat or alter the CNS have been scientifically evaluated. To date very few of the active compounds have been isolated and identified

    Medicinal plant use in the Dwarsrivier Valley, Stellenbosch

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    Magister Scientiae (Biodiversity and Conservation Biology)Plants have been used as medicine since antiquity. Passed on by word of mouth through the generations, this oral tradition is at risk of becoming extinct due to westernization and lack of documentation. The community in the Dwarsrivier valley is one such community who continues to use these medicinal plant remedies on a daily basis. However, these remedies are at risk of becoming extinct due to a lack of interest from the younger generation. The objectives of the study were to identify the plants used for medicinal purposes, provide an inventory and select several plants for elemental analysis and phytochemical screening. Individuals were selected based on their ethnobotanical knowledge and agreed to participate in the study. Over 40 individuals were interviewed from the four communities; Pniel, Lanquedoc, Meerlust and Kylemore. Of the 40 participants interviewed, 25 participants agreed to complete questionnaires. The survey yielded 53 plant species belonging to 31 families of which only 24 are indigenous. Although more exotic plants are used compared to indigenous, the indigenous plants were the more popular choice for medicinal use. Most plants belonged to the Lamiaceae family followed by Asteraceae, Alliaceae, Apiaceae and Rosaceae. The most popular plants in terms of ranking are Agathosma crenulata followed by Artemisia afra and Helichrysum petiolare. This is the first report of Protea cynaroides, Cissus rhombifolia, Canna spp. and Dilatris viscosa used for medicinal purposes

    The antimicrobial investigation of indigenous South African medicinal plants against oral pathogens

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    A dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the degree of Master of Pharmacy, Johannesburg, 2017Oral diseases in South Africa remain a huge public health problem due to the high cost, prevalence, severity and the influence on the patients well-being. Treatment for oral diseases requires the need for specialist dental health care workers and come at a high cost causing a great burden on the health system. The three most important oral diseases are dental caries, caused by Streptoccocus mutans, Streptococcus sanguis, Lactobacillus acidophilus and Lactobacillus casei, periodontal diseases caused by Porphrymonas gingivalis and Fusobacterium nucleatum and oral candidiasis caused by Candida albicans, Candida glabrata and Candida krusei. An ethnobotanical review has revealed that over a 120 South African medicinal plants are used for the treatment of oral diseases. This coupled with the lack of research on the subject, allowed for the investigation of the antimicrobial efficacy of some South African plants against oral pathogens. A total of 140 aqueous and organic extracts and six essential oils were prepared from 31 different plant species. These plant samples were screened for antimicrobial efficacy against nine oral pathogens using the micro-titre plate dilution assay. Plant extracts that were found to have noteworthy antimicrobial activity against Streptococcus mutans were further evaluated on the effect on S. mutans biofilm formation using the glass slide method. The toxicity profiles of plant samples that were found to have noteworthy antimicrobial activity were evaluated using the brine shrimp lethality assay. The plants did not exhibit antimicrobial efficacy against all nine pathogens in this study, instead, most were very specific to disease conditions. Some plants did show good antimicrobial activity against four of the nine pathogens tested (A. afra leaves, C. torulosa stems, C, brachiata leaves and H. natalensis leaves).The organic extract of Cissampelos torulosa stems displayed the lowest MIC value of 0.05 mg/ml against both Lactobacillus spp. This antimicrobial activity was also observed with the organic extract of Spirostachys africana leaves against Candida albicans. In some instances, a direct relationship was found between the traditional use of the plant and the antimicrobial activity observed. For example, noteworthy activity (MIC < 1.00 m/ml) was observed against all three Candida spp. for Clematis brachiata (leaves), a plant traditionally used to treat oral thrush. Englerophytum vi magalismonatanum (stems) displayed notable activity against both Streptococcus spp. (MIC 0.83 mg/ml against S. mutans and MIC 0.67 mg/ml against S. sanguis). Spirostachys africana leaves displayed the greatest anti-adherent properties against S. mutans biofilm formation at both 24 and 48 h, reducing the biofilm by 97.56% and 86.58% respectively. The majority of plant samples tested in the brine shrimp lethality assay (BSLA) were considered safe, however, 13 plant samples were considered toxic, at a concentration of 1 mg/ml, and their LC50 values were determined. The findings from the results favour the potential use of these plants in treating oral diseases such as dental caries, periodontal diseases and oral thrush, and scientifically validates the traditional use of some of these plants.XL201

    Medicinal ethnobotany of the Little Karoo, South Africa

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    Abstract : Please refer to full text to view abstract.D.Phil. (Botany

    Antidiabetic compounds from Hypoxis colchicifolia and Terminalia sericea.

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    M. Sc. University of KwaZulu-Natal, Pietermaritzburg 2015.In this project two medicinal plant species, namely Hypoxis colchicifolia Bak (Hypoxidaceae) and Terminalia sericea Burch. (Combretaceae), have been investigated and different compounds isolated and characterised. The aim of this study was to investigate the phytochemistry and antidiabetic activity of H. colchicifolia and T. sericea. H. colchicifolia (H. latifolia) is after H. hemerocallidea (African Potato) the second most important Hypoxis medicinal species with commercial value in South Africa. From the methanol extract of the corms, four phenolic derivatives, hypoxoside, a mixture of dehydroxyhypoxoside A and B and bis-dehydroxyhypoxoside were isolated, as well as an environmental impurity bisphenol A diglycidyl ether. This is the first study on the isolation of the dehydroxyhypoxoside B. The methanol extract of H. colchicifolia showed glucose lowering effects and low toxicity in vitro against C2C12 muscle cells and Chang liver cells. Of the pure compounds, only the mixture of dehydroxyhypoxoside A and B showed an increase in glucose utilization by the muscle cell line C2C12. T. sericea is an important plant in traditional medicine and is in the top 50 most important African medicinal plants. From the methanol extract of the roots, one known compound, sericic acid, was isolated. The methanol extract of T. sericea roots showed an increase in glucose utilization by C2C12 muscle cells and Chang liver cells but the extract also showed some cytotoxicity towards these cells. Structural elucidation of the different compounds was achieved by using NMR spectroscopy in one and two dimensions, high-resolution mass spectrometry, infrared spectroscopy and ultraviolet spectroscopy

    An ethnobotanical, phytochemical and metabolomics investigstion of plants from the Paulshoek Communal Area, Namaqualand

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    Includes bibliographical references.The aim of this thesis is to investigate medicinal plants from different perspectives in an attempt to arrive at a new, integrated and streamlined method for the discovery of bioactive secondary metabolites of plant origin. This will be done through a focused study of the traditionally used medicinal plants of the Paulshoek region of Namaqualand and a demographic study of the people who use them. Trends in traditional medicinal plant choice will be investigated and methods of traditional knowledge acquisition and transfer will be examined. Additional assessment of bioactivity and trends in bioactivity will be conducted and a variety of physico-chemical and computational techniques will be used to determine the major metabolites present in selected plant species. These different approaches to medicinal plants will be brought together in a single holistic method put forward as a possible way of conducting future studies into discovering active metabolites for potential drug development

    The role of geophytes in stone age hunter-gatherer subsistence and human evolution in the greater cape floristic region

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    It has been hypothesised that an adaptive shift to a starch-rich diet was an important driver in human evolution and supported the energetic requirements to sustain brain development throughout hominin evolution. Plants that possess underground storage organs (geophytes) have been put forward as the likely source of starch. Geophytes comprise a large portion of the plant diversity in the Greater Cape Floristic Region (GCFR), where significant archaeological evidence of the evolution of human modernity has been identified in the Middle Stone Age (MSA). It is thought that the resources available in this region during this time period fuelled the progression and development of complex language, art and tool production in early modern humans. The overall objective of this thesis is to determine the importance of geophytes in early modern human diets and the impact they might have had on human behaviour and cognition. The role of geophyte resources in Stone Age hunter-gatherer subsistence was evaluated by firstly creating an ecological and environmental framework of data to evaluate the geophyte resource base. Secondly, the archaeological evidence available on actual hunter-gatherer foraging behaviour was evaluated using this framework, together with novel methods of macrobotanical analysis and experimental archaeological methods. It was found that the nutritional quality of geophytes is high, even in comparison to domesticated crops such as potatoes. The desirability of geophytes to a forager would rely on many factors, apart from nutritional quality, however. Geophyte resources on the coastal plain of the GCFR are dense and diverse. This diversity encompasses variation in the quality of the nutrients contained in the USOs and the optimum time throughout the year they would be most profitable to harvest. Geophytes could have been available during a large portion of the year throughout the GCFR. The archaeological evidence shows just how widespread and complex geophyte foraging and processing were during the Holocene, although there is a relative lack of evidence in the MSA. The novel method presented to determine the energy cache offered by geophytes and the seasonality of geophyte foraging shows great promise to improve our understanding of foraging choices and hunter-gatherer mobility across the region. All Stone Age processing methods tested experimentally improved the nutritional quality of USOs, but veldfire produced the most profound nutritional quality improvements of all methods tested. Geophytes could have supplied the dense and predictable resource cache that made the GCFR a reliable environment for human evolution, despite climatic and vegetational shifts. The efficient exploitation of geophyte resources throughout the Stone Age could have altered early human behaviour and cognitive development

    Identification of triterpenoids in Brachylaena discolor DC, a plant with antidiabetic activity.

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    Masters Degree. University of KwaZulu-Natal, Pietermaritzburg.In recent times, metabolic diseases such as diabetes and hypertension have become a huge burden in populations around the world. Among these diseases, the number of diabetes mellitus cases have been increasing at an alarming rate. Problems such as poor access to medication and side effects of existing drugs are encountered and there is still a need for more therapeutic alternatives. Plants have been used extensively for the treatment of various diseases, among them diabetes. Brachylaena discolor DC is a South African medicinal plant that is used by people for the treatment of diabetes and it has been reported previously to have antidiabetic activity with little toxicity. This study aimed to investigate the triterpenoid content of B. discolor and further evaluate the plant for in vitro antidiabetic activity by inhibition of the enzyme α-glucosidase, a therapeutic target for treatment of diabetes. In literature, it has been reported that some triterpenoids are good inhibitors of α-glucosidase. Chromatographic techniques, including argentation chromatography on silica gel impregnated with silver nitrate, were used in the isolation of compounds. The compounds were identified by 1D and 2D NMR (i.e. 1H, 13C, COSY, DEPT, HSQC and HMBC), IR, GC-MS, and HR-MS. From the dichloromethane extract of B. discolor leaves, eight triterpenoids were isolated, α-amyrin acetate, β-amyrin acetate, ψ-taraxasterol acetate, taraxasterol acetate, lupeol acetate, α-amyrin palmitate, β-amyrin palmitate, and lupeol palmitate. All the compounds are reported for the first time from the plant, except lupeol acetate, which was previously identified in the plant. Hydrolysis of α-amyrin acetate, β-amyrin acetate, ψ-taraxasterol acetate, taraxasterol acetate, and lupeol acetate afforded the alcohol triterpenoids α-amyrin, β-amyrin, ψ-taraxasterol, taraxasterol, and lupeol. The DCM-MeOH (1:1) leaf extract of B. discolor was investigated in vitro against α-glucosidase and the extract was to inhibit the enzyme significantly with an IC50 value of 95.95 μg/mL when compared with the standard inhibitor acarbose with an IC50 value of 1149.07 μg/mL. The individual pure compounds were not assayed due to poor solubility in the assay medium. Molecular docking studies revealed that the triterpenoids, α-amyrin, β-amyrin, ψ-taraxasterol, taraxasterol, and lupeol all have binding affinity for the α-glucosidase active site, where α-amyrin and β-amyrin showed more pronounced results with binding energies of -8.90 and -8.00 kcal/mol, respectively. In the study the reported antidiabetic activity of B. discolor was corroborated

    Ethnobotany of Namaqualand : the Richtersveld

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    Bibliography: p. 145-152.The primary aim of this ethnobotanical dissertation was to provide a biobehavioural focus for indigenous plant use in the semi-arid areas of one of the six so-called Coloured Rural Reserves (Komaggas, Concordia, Richtersveld, Steinkopf, Leliefontein and Pella) in the north-western Cape (Namaqualand). Although much of the indigenous plant lore has been lost through westernization, the descendants of the Nama-speaking Khoi pastoralists, who are traditionally associated with Namaqualand, still partially rely on indigenous plants for subsistence. Firewood is used daily, medicinal plants are collected regularly and edible plants as well as plants used for household and other activities (such as dyeing of leather) are often used. This project can be seen as a rescue operation to obtain information on the use of indigenous plants before this fast-disappearing knowledge is lost. Richtersveld (and Leliefontein, for comparative and enrichment purposes only) were selected because literary sources confirm the observation that these are the areas where customary practises persist. A biobehavioural approach in terms of human-plant interactions has been applied. The main focus of the dissertation is on the diversity of useful plants and the range of activities associated with the use of the plants. The characteristics of the plants have been examined from an emic as well as etic perspective. The emic perspective was found to be particularly significant in assessing plant foods as well as medicinal plants. Etic perspectives were obtained through nutrient analyses of edible plants and discussions and literary research on medicinal compounds in plants used in health care. It seems that the emic and etic perspectives about plants are not as distinct as was initially thought. Peoples' perceptions about the plants guide them in their choice of plants but it is clear that some biological characteristics of the plants give rise to many of these choices. It may be possible to develop a system of criteria for different categories of plants which will enable archaeologists to make inferences about human-plant interactions. The dissertation ends by commenting on the archaeological significance of the way in which plants are used. The conclusion is that the archaeological record is a poor reflection of the range of activities associated with plant use; and a poor reflection of the diversity of plants which are used in subsistence strategies of the pastoralists of Namaqualand
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