Healthcare in South Africa is polarised between western and traditional African systems of therapy. The latter is consulted by the majority of the population and therefore plays an integral role in the delivery of healthcare to South Africans. Traditional medicines are primarily plant products with long storage lives, among which the dominance of bark is typical of southern African traditional healthcare systems. Expansion of the traditional healthcare sector during the twentieth century, in response to rising consumer demands, stimulated a lucrative trade in medicinal plants that is centred in KwaZulu-Natal. Since herbal medicines are sourced almost exclusively from indigenous vegetation, harvesting pressures exerted on the indigenous flora to meet demands for traditional medicines have rendered such resources non-sustainable. Although trees comprise a small fraction of South African medicinal plant species, bark from them constitutes a substantial proportion of the plant products used medicinally. Trees are among the most threatened medicinal plants in South African due to their limited abundance, the ecological sensitivity of the vegetation in which they occur, and destructive methods of commercial bark harvesting that frequently take place within protected areas. In KwaZulu-Natal, bark is harvested primarily from forests that occupy an extent of only 0.1 % in the province. Conservation of economically valuable tree species is particularly problematic since data necessary for the establishment of sustainable usage systems are absent or inaccessible. Alternatives to in situ conservation for renewable bark resources include propagation, multi-use timber systems and reintroduction of locally extinct species. To facilitate appropriate management of bark resources, there is a need for specialist publications and consolidated data with which sustainable usage levels may be determined. The importance of bark in South African traditional healthcare is poorly reflected by the ethno botanical literature. In this study, 180 bark species used in traditional healthcare in KwaZulu-Natal were inventoried from thorough literature surveys, but this number is anticipated to be a conservative reflection of actual statistics. Where trade data were recorded in the literature, they indicated intensive exploitation of bark resources in KwaZulu-Natal and throughout South Africa, but conservation and management data were lacking for 72 % of the species inventoried. A number of problems were encountered in the literature, of which vague information and the documentation of local vernacular nomenclature were the most troublesome. Despite the importance of traditional medicine, the country's political history led to the prevailing situation, where the traditional healthcare sector is largely unregulated. Coupled with increasingly limited availability of medicinal plants, the quality and appropriate use of traditional medicines is negatively affected by growing numbers of inadequately trained practitioners, herbalist retailers and plant gatherers. Possibilities of misidentification or purposeful adulteration of medicinal bark products therefore lead to concerns for patient safety, since dried bark is difficult or impossible to identify. Whilst bark characters are useful for field identifications, many useful diagnostic characters are lost through desiccation, and anatomy and morphology of bark are variable. Additionally, medicinal bark products used in KwaZulu-Natal, and their identification, are largely undocumented. This study focussed on eight bark species used medicinally in the province, elected by an esteemed traditional medical practitioner as having problematic identity. Monograph-type characterisation profiles were drawn up for reference specimens collected from various localities, and their medicinal bark products traded under vernacular names recorded in the literature. In the absence of standardised traditional medicines, there is a need for reliable and affordable methods for their authentication. Phytochemical bark characters identified by Thin Layer Chromatography (TLC) have proved useful in chemotaxonomic studies, and the technique is widely used for herbal drug authentication. TLC was tested here for authentication of medicinal bark products from the aforementioned study species. Three reference samples of each species were collected, and TLC-generated fingerprints compared. At the intraspecific level, TLC was useful in confirming the relationship of ethanol and hexane bark extracts, but was less meaningful in distinguishing between fingerprints of different species. Three medicinal bark products of each study species were purchased and fingerprints compared to a reference. The technique proved useful in confirming the identity of several medicinal bark products. Authentication of medicinal bark products may be useful in toxicology cases and in the accurate documentation of their trade. This research identified a complexity of issues surrounding the use of bark in traditional healthcare in KwaZulu-Natal, and indeed South Africa. A multi-faceted approach is required to secure their sustainability. Critical, however, to factors such as effective conservation and regulation of the traditional healthcare sector, is recognition of the importance, and documentation, of traditional bark medicines. The integrity of traditional healthcare, and the future of the South African flora, hinge upon the sustainable use of medicinal products such as bark. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.

Submitted in complete fulfillment for the Degree of Master of Technology: Biotechnology, Durban University of Technology, 2013. / The biosynthesis of NPs has many advantages over the tedious, expensive and toxic physical and chemical methods of synthesis. Plants are stocked with valuable metabolites that are capable of reducing metal salts to form NPs. In this study, aqueous leaf extracts of A. dubius, G. perpensa, C. roseus and C. triloba were reacted with AgNO3 and HAuCl4 to determine the plants reducing abilities and hence synthesis of Ag and Au NPs capabilities. The synthesis reactions were carried out at different temperatures and extract concentrations for optimization. The goal was to form NPs within the specific wavelength range. Polar solvents: methanol and ethyl acetate extractions were carried out at the optimized conditions to evaluate the best solvent for the extraction of phytochemicals from the plants. The plant leaf extracts that were successful (A. dubius, G. perpensa and C. triloba) in synthesizing NPs were then micropropagated to form callus cultures. The reducing abilities of these callus cultures extracts were determined by varying temperature and concentration parameters. Characterization of the NPs formed by the different extracts was performed using UV-vis, TEM and FTIR. UV-vis spectrophotometry was used as a confirmatory as well as characterizing tool. TEM analysis was able to provide a description on the size and shape of the NPs whereas FTIR provided information on the biomolecules responsible for synthesis and capping of NPs. The stability of the NPs was determined by UV-vis scans over a period of 30 days which allowed observation of the alteration in peak shape and absorbance and hence condition of particles. Phytochemical tests were performed on the leaf extracts of the four plants to elucidate possible phytochemicals responsible for the reduction of metal salts. Antibacterial activity of the NPs was evaluated by using the disk diffusion assay and MICs were determined by the broth dilution method against pathogenic bacteria. A. dubius, G. perpensa and C. triloba were capable of synthesizing Ag NPs and Au NPs which were indicated by yellowish orange and reddish purple colour changes respectively. G. perpensa was able to spontaneously form Ag and Au NPs without any addition of heat whereas A. dubius and C. triloba required heat to form Au NPs. As the temperature of the reactions increased, the absorbance and possibly the number of NPs produced, increased. When the concentration of the extract was doubled, the absorbance was seen to decrease. C. roseus did not produce any Ag or Au NPs with any of the leaf extracts. Only A. dubius and C. triloba callus extracts were investigated for NP synthesis and it was found that A. dubius callus extracts were unsuccessful in synthesizing NPs and C. triloba callus extracts were able to form unstable Ag and Au NPs. The spherical Ag NPs that were formed from aqueous extracts of A. dubius were slightly larger than the methanolic Ag NPs. The Ag NPs produced by G. perpensa were in the same size range for aqueous and methanolic extracts. C. triloba Ag NPs formed from the methanolic extract were closer in size to A. dubius aqueous Ag NPs but the C. triloba aqueous extract produced much larger Ag NPs than the other extracts. The Ag NPs produced from A. dubius aqueous and methanolic extracts as well as C. triloba methanolic extracts exhibited the longest stability of 30 days. Ag NPs from G. perpensa aqueous extracts had the least stability. G. perpensa did not form any hexagonal Au NPs and the spherical and triangular Au NPs were smaller unlike in A. dubius and C. triloba Au NPs. The Au NPs formed by the aqueous extracts of A. dubius and C. triloba were larger in comparison to their methanolic counterparts. The Au NPs produced from G. perpensa aqueous and methanolic extracts as well as A. dubius and C. triloba methanolic extracts exhibited the longest stability of 30 days. Au NPs were stable for longer in comparison to Ag NPs. FTIR provided evidence that Ag and Au NPs have a chemical bond with the amide group in amino acids. However the intensities of biomolecules for Au NPs are more pronounced compared to the Ag NPs. It was also found that the Ag NPs synthesized by methanolic leaf extracts have slightly higher intensities than Ag NPs synthesized from aqueous leaf extracts. Phytochemical screening showed the absence of tannins in the C. roseus leaf, A. dubius and C. triloba callus extracts and presence in the other three plants. C. triloba methanolic extract Ag NPs showed the highest activity against Gram-positive S. aureus. Aqueous and methanolic Ag NPs from G. perpensa and C. triloba as well as A. dubius methanolic Ag NPs had activity against all fourteen bacteria. A. dubius aqueous Ag NPs had no activity against Enterobacter spp. and a strain of Klebsiella pneumoniae. G. perpensa Ag NPs had better antibacterial activity and lower MICs against Gram-positive and Gram-negative pathogenic bacteria compared to A. dubius and C. triloba. There was no antibacterial activity seen with Au NPs. The size and shape of NPs are the keys to their biomedical properties. Green synthesis of NPs is a feasible way for the future. This study showed that NPs can be synthesized very easily and economically. A key finding of this study is that different plants produce varying sizes and aggregation of NPs. / National Research Foundation

Dissertation submitted in fulfilment for the requirements of the Degree of Master of Technology in Biomedical Technology, Durban University of Technology, 2012. / Introduction Medicinal plants have been used for centuries as remedies for human diseases because they contain components of therapeutic value. Recently, the acceptance of traditional medicine as an alternative form of health care and the development of microbial resistance to the available antibiotics have led scientists to investigate the antimicrobial activity of medicinal plants Aim The aim of this study was to investigate the antimicrobial activity of extracts obtained from medicinal plants used in traditional medicine. A comparative study was carried out on the antimicrobial properties of extracts obtained by two different methods in order to choose that which extracts the most effective antimicrobial compounds. Methodology The plants used in this study Artemisia afra, Erythrina lysistemon and Psidium guajava were harvested from the Silverglen Nature Reserve (Chatsworth) early in the morning (8 a.m.). The leaves of A. afra and P. guajava extracts and the bark of E. Lysistemon were used to prepare the extracts. All plant extracts were prepared according to modified method of the German Homeopathic Pharmacopoea. Two solvents, water and 60 percent ethanol were used to extract the antibacterial compounds from plant material. The extracts were then assessed for their antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. The effect of the plant extracts on these bacteria was determined by the disk diffusion test, which was used as the screening test. Positive results were further subjected to the minimum inhibitory concentration and minimum bactericidal concentration assays. Tubes that showed no turbidity were then sub-cultured onto non-selective plates. Bacterial sensitivity testing was carried out in accordance with modified Kirby-Bauer Antimicrobial Sensitivity Test. An attempt was made to identify some antibacterial compounds using Thin Layer Chromatography and High Pressure Liquid Chromatography. Results None of the gram negative organisms were inhibited by Artemisia afra, Erythrina cafra and Psidium guajava. Only the ethanol extracts of all three plants were able to inhibit Staphylococcus aureus but not Escherichia coli and Pseudomonas auruginosa. None of the test organisms were inhibited by the aqueous extracts of all three plants used in this study. In the screening test, the zones of inhibition for ethanol extracts against Staphylococcus aureus ranged from 3mm – 7mm. The minimum inhibitory concentration ranged from 16.67 percent – 83.3 percent inhibition depending on the dilution of the extract. Quercetin and Catechin were identified as some of the antibacterial compounds present in the leaves of Psidium guajava. These two compounds were not identified on Erythrina lysistemon and Artemisia afra. Conclusion The results obtained in this study have proven that Artemisia afra, Erythrina cafra and Psidium guajava ethanol extracts contain antibacterial substances. The ethanol extracts of all plants in this study inhibited the growth of Staphylococcus aureus but had no effect on the gram negative bacteria. Aqueous plant did not inhibit the growth of any bacteria in this study. This study has also shown that antibacterial effect of these extracts may be considerably enhanced in traditional treatment if traditional healers can include ethanol as one of the extraction solvents. The results obtained in this study might be considered sufficient for further studies aimed at isolating and identifying the active compounds and evaluating possible synergism of antimicrobial activity among these extracts. Investigations on toxicity of these extracts should also be carried out.

The dichloromethane extracts (1 mg/ml) of Artemisia pacifica Nutt and Guardiola platyphylla Gray (fam. Asteraceae) separately demonstrated in vitro growth inhibition of Staphylococcus aureus (UA 9-29), Bacillus subtilis (UA 2-27), Klebsiella pneumoniae (UA 3-9) and Candida albicans (UA 97). Each of these extracts were subjected to bioassay-directed solvent extraction and partition in order to obtain concentrated active fractions. Subsequently, the active compounds were isolated and identified from these fractions. Artemisia pacifica Nutt. The active compound was the major component isolated from A. pacifica. By comparing the physical and chemical data with previously reported data, this compound was identified as dehydrofalcarindiol. Dehydrofalcarindiol demonstrated growth inhibition against S. aureus (50 μg/ml), B. subtilis (25 μg/ml), K. pneumoniae (100 μg/ml) and C. albicans (25 μg/ml). Its diacetyl derivative was devoid of activity at 100 μg/ml. Guardiola platyphylla Gray. The active fraction obtained from G. platyphylla contained unstable compounds that decomposed in the presence of air. Size exclusion chromatography (Sephadex LH-20) was used to fractionate the active fraction. Two new sesquiterpenes, the o-catechol derivatives (1S,4S) and (1S,4R)-7,8-dihydroxy-11,12-dehydrocalamenene, were eluted from the column as a mixture. The mixture of their diacetyl derivatives was oxidized with CrO₃ in AcOH. The major oxidation product was identified as (1S)-7,8-diacetyl-4-oxodeisopropylcalamenene, thereby verifying the sole difference to be the configuration at C-4. This sesquiterpene mixture completely inhibited the growth of S. aureus (100 μg/ml), B. subtilis (50 μg/ml), K. pneumoniae (100 μg/ml) and C. albicans (100 μg/ml). After removal of the sesquiterpenes from the active fraction, the remaining compounds displayed the same level of activity. Another six compounds were also isolated from this mixture as acetylated derivatives due to their instability. Their dimeric structures were identified by 2D-NMR techniques (COSY, HETCOR and NOESY). These dimers may be artifacts since they were formed from their o-quinone monomers when kept at room temperature for a week or when heated at 60°C for 4 hours.

This study aimed to evaluate the antimicrobial efficacy of medicinal hemp plant extracts to determine the antibacterial effects of indigenous Sansevieria species and exotic Cannabis sativa phytotherapy varieties. This study also assessed whether aqueous o

<p>Since Helichrysum is known by the indigenous people of Africa for therapeutic properties, such as against colds, flu and wounds, the aim of this study was to focus on the patulum species found predominantly in the Western Cape region of South Africa and by means of isolation and identification of the plant constituents, be able to relate the therapeutic activity on the basis of literature precedents, to the compounds extracted.</p>

Neobeguea mahafalensis Leroy. and Cedrelopsis grevei Baill. are the two Madagascan species which were investigated in this work. Neobeguea mahafalensis Leroy. belongs to the Neobeguea genus of the Meliaceae family and is a plant unique to Madagascar. It is commonly referred to as "Handy" by the native people of Madagascar, who use it as a medicinal plant. The stem-bark of N mahafalensis which has been analysed in this work, was collected from the dry, thorny forests of the deep south of Madagascar. Most species found in this region are unique in the world and are highly specialised in adapting to the very dry climate. The hexane extract was found to yield a limonoid (compound I) which has not been previously reported as a natural product. The known pentacyclic triterpenoid, j3-amyrin (compound II) and stigmasterol (compound III), were also isolated. Cedrelopsis grevei Bail!. is one of seven species of the genus Cedrelopsis which are confined to Madagascar. This species, commonly referred to as "Katrafay" by the Madagascan people, has undergone intensive chemical investigation as prior inclusion ofthis species in the Meliaceae family has always been questionable. The South African species Ptaeroxylon obliquum (Thung.) Radlk., is a member of the Ptaeroxylaceaefamily which is found to be so chemically similar to Cedrelopsis that the latter has been placed in the Ptaeroxylaceae family. The stem bark of Cedrelopsis grevei was obtained from the dry southern part of Madagascar and yielded a variety of chromones and coumarins, as well as stigmasterol (compound III) and the pentacyclic triterpenoid, j3-amyrin (compound II). Two chromones were isolated from Cedrelopsis grevei, namely ptaeroxylinol (compound IV) and ptaeroglycol (compound V). Ptaeroglycol has been previously isolated _from this species as well as from Ptaeroxylon obliquum whereas ptaeroxylinol has only byen isolated from Ptaeroxylon obliquum. Six coumarins were isolated from Cedrelopsis grevei in tillS study, all of which were 6,7-dioxygenated coumarins. These included the known compounds, scoparone (compound VI), O-methylcedrelopsin (compound VIII), norbraylin (compound X) and cedrelopsin (compound IX), as well as compound VII and compound XI which . have not been reported previously. No limonoids were isolated from this species in this investigation. / Thesis (M.Sc.)-University of Natal, 1997.

Four species belonging to the Hyacinthaceae family were investigated. The taxonomy of the Hyacinthaceae is currently under review and therefore compounds isolated from these plants could provide valuable chemical evidence which taxonomists could find very useful. The bulbs of the species investigated have been reported to have widespread uses in traditional African medicine, being used by different local tribes to treat a variety of ailments ranging from use as a soothing medicine for pregnant women to their being used as an ethnoveterinary medicine. The bulbs of Ledebouria cooperi are specifically used as an anti-inflammatory agent during circumcision ceremonies. The bulbs investigated were found to contain homoisoflavonoids, a class of compounds known to be specifically responsible for the anti-inflammatory properties of these plants when used by traditional healers. The bulbs of L. cooperi were found to contain two known homoisoflavonoids as well as a triterpenoid. Malic acid was also isolated from the methanol extract. A further homoisoflavonoid of the 3-benzyl-4-chromanone type was isolated from Scilla plumbea. Drimiopsis maculata was found to be an abundant source of natural products from which two scillascillin-type homoisoflavonoids as well as two aromatic compounds were isolated. Investigation into the fourth species, Drimia robusta, yielded an uncommon bufadienolide. As no spectroscopic information was available for this compound, the complete assignment of the compound was performed using 2-D NMR spectroscopy. / Thesis (M.Sc.)-University of Natal, Durban, 2000.

Bulbs of Scilla natalensis Planch, Scilla nervosa (Burch.) Jessop, Scilla dracomontana Hilliard and Burt and Scilla kraussii Bak. (Hyacinthaceae) were investigated. The plants are widely used by the local African people for a variety of ailments that inflict them and their livestock. Plant material was harvested in different localities i.e. KwaZulu-Natal (KZN) and Mpumalanga (Mpl). The bulbs have been found to contain homoisoflavonoids and stilbenoids. Ten homoisoflavonoids and two stilbenoids were isolated. Of the ten homoisoflavonoids isolated, nine were of the 3-benzyl-4-chromanone type while one was a 3-benzylidene-4-chromanone. Four of the 3-benzyl-4-chromanones were found to be novel compounds while others were recognised as having been reported before from other genera within the family Hyacinthaceae viz., Eucomis and Muscari. The 3-benzylidene-4-chromanone type compound isolated was also found to be a known compound. The stilbenoids, on the other hand, are reported for the first time in this genus although they seem to have a wide distribution in the plant kingdom. The structures of the isolated compounds were elucidated using spectroscopic methods. / Thesis (M.Sc.)-University of Natal, Durban, 1998.

Three species have been investigated in this project: Iso-ocobullenone (p 23) and its probable precursor (p 27) have been isolated from the leaves and bark of Ocotea kenyensis. This is only the second time that these compounds have been isolated and the first time from this species. The isolation of these two compounds in the leaves establishes a commercially important chemical link with the bark. The bark of the closely related Ocotea bullata is the most sought after source of "muthi" in the Kwa-Zulu Natal region and it is becoming a very scarce commodity. The leaves of Ocotea kenyensis have also yielded related compounds including A8'-3,5-dimethoxy-3',4'-methylenedioxy-l ',2',3',4'-tetrahydro-6' -oxo-7,1',8,3'-neolignan which is described here for the first time. Other compounds isolated were bacterialprenol, triacontane, B-sitosterol and a previously undescribed isoprenoid. An investigation into the molluscicidal potential of compounds in Apodytes dimidiata was extended with a view toward control of the population of the intermediary snail host for bilharzia-causing trypanosomes. This study afforded the known compounds squalene, lupeol, betulinic acid and catechin. The synthesis of a previously isolated compound, 4-ethyl catechol, with molluscicidal activity was successfully completed and its structure and activity were confirmed. A bio-assay guided isolation procedure was used to determine the potential value of compounds in Ehretia rigida for the control of sleeping sickness. Allantoin, a- and B-amyrin, triacontanol and B-sitosterol were isolated. Activity of the extracts was not high enough to be of commercial value. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998