In most countries, as many as 15 to 25% of the adult population have raised blood pressure. People with hypertension, and even those with mild elevation of blood pressure, are at an increased risk of cardiovascular disease, whether or not the symptoms are present. The risk of serious cardiovascular disease varies greatly among individuals and is also determined by a variety of concomitant risk factors other than the level of blood pressure. Hypertension develops as a result of disturbances of the body's blood pressure regulating system. The biological activity of the renin-angiotensin systems results from a series of specific enzymatic cleavages leading to the generation of angiotensin II, a potent vasoconstrictor. In the treatment of hypertension, inhibition of the angiotensin converting enzyme is established as one modern therapeutic principle. Angiotensin converting enzyme inhibitors act by inhibiting the conversion of angiotensin I to angiotensin II. The in vitro assay, developed by ELBL and WAGNER (1991) for the detection of angiotensin converting enzyme inhibitors in plant extracts was successfully established during this study. Plants used by traditional healers in South Africa for the treatment of high blood pressure were investigated for their antihypertensive properties, utilizing the established angiotensin converting enzyme assay. Twenty plants were investigated for their angiotensin converting enzyme inhibitory activity. The highest inhibition (97%) was obtained by Adenopodia spicata leaves. A further seven plants exhibited an inhibition greater than 70% and five more over 50%. Plants exhibiting inhibition levels greater than 50% were further tested for the presence of tannins in order to eliminate possible false positives. The leaves of Tulbaghia violacea were chosen for bioassay-guided fractionation in an attempt to isolate the active compound(s). Serial extractions were made of ground Tulbaghia violacea leaves using polar to non-polar solvents to establish the solvent giving optimum extraction of the active compound(s). Distilled H2O was selected as the extractant and a bulk extract was performed on 0.7 kg ground leaves. The extracted residue was partitioned against butanol, fractionated using cation exchange resin chromatography, Sephadex ® LH-20 and high performance liquid chromatography. Fractions collected after each purification step were assayed using the angiotensin converting enzyme assay. Fractions exhibiting high levels of angiotensin converting enzyme inhibition were selected for further purification. The active fraction from the final high performance liquid chromatography step used in this study requires further attention in order to purify and identify the active compound(s). The chromatographic and chemical properties of the compound(s) present in the isolated active fraction are discussed. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.

Coleonema album is a South African green treasure, endemic to the Cape region and hard to find in other parts of the country. It is ranked among the most highly utilized medicinal plants at present. The plant extracts exhibit a wide range of pharmacological activities due to its bioactive compounds. Immunat, a tincture from this plant is marketed commercially. Medicinal plant gatherers are on the lookout for this plant due to its high demand and market price. Several natural product companies in South Africa are now exporting Coleonema album oil. Its showy beautiful white flowers make it a valuable ornamental plant. There is no accredited germination protocol available for this medicinal and ornamental plant till date. In this study, the chemical and environmental conditions required for optimum seed germination and seedling growth were studied. The effect of light, temperature shifts, cold and warm stratifications, smoke-water, butenolide, pH levels, plant growth regulators (kinetin, 6-benzyladenine, indole acetic acid and α-Naphthalene acetic acid), salt solutions (sodium chloride and ammonium nitrate) on seed germination were investigated. Seeds showed favourable response of germination at low temperatures (10 and 15 ºC). Seeds exposed to continuous darkness at low temperatures showed highest germination at 15 ºC. Temperature shift (from 20 ºC to 15 ºC) favoured seed germination. pH 6 is the most conducive pH level for Coleonema album seed germination (52.5%). Sodium chloride and ammonium nitrate solutions (pretreatment for 2 weeks) significantly improved germination at a 10-2 M concentration with 62.5 and 75% germination respectively. Coleonema album seeds exhibit a temperature-dependent physiological dormancy. Seed germination of this plant is quite erratic as seed germination started 21 days after incubation and lasted for over 90 days. Germination rate of the seeds is too slow to meet the local and international demand for this plant. Plant tissue culture techniques have been used as an alternative for mass cultivation of plants that are difficult to propagate from seeds. Therefore, an effective micropropagation protocol was developed as a measure to conserve this highly utilized medicinal plant. The effects of the cytokinins: BA, kinetin, TDZ and topolins on in vitro shoot formation of Coleonema album were investigated. Of all the cytokinins tested, 5 μM mT gave the highest number of shoots (14.50) per explant. Combination of 5 μM mT with various concentrations of IBA and NAA significantly increased shoot production. Shoots cultured on IBA supplemented medium produced roots. Root production from NAA cultures is unfavourable as most of the shoots developed callus at the base of the stem. The result of this study has shown that mT has potential as a highly active alternative to BA and other cytokinins for Coleonema album in vitro shoot production. Over 1,000,000 plantlets could be produced annually using the in vitro propagation protocol developed in this study. The results of this study will be useful as a guide for mass cultivation of this ornamental and medicinal plant. It will also provide an opportunity for propagation of Coleonema album in other parts of the country. By virtue of this, the pressure on the wild population of this species could be greatly reduced. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2012.

Three plant species (Phylica paniculata Willd., Pergularia daemia Forssk. and Monsonia / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

This project is focused on the synthesis and biological activity of aloin and derivatives. Aloin is a C-glucoside anthrone that is found in Aloe marlothii, a common Southern African plant used in traditional medicine. Aloin was isolated from A. marlothii, employing a selective chelation isolation procedure. This compound is known to have numerous biologically active properties, and can be used as a laxative, an anti-bacterial agent, an anti-oxidant, and as a cytotoxic drug against breast and ovarian tumour cell lines. More relevant to this research investigation, was the reported anti-inflammatory activity of aloin. Specifically, the inhibitory activity of aloin on matrix metalloproteinases, which when excessively secreted, can lead to the development of osteoarthritis and cancer metastasis. Aloin has also been reported to have antiplasmodial activity, which was also investigated. Aloin was synthetically transformed into several derivatives, which could be potentially useful medicinal compounds. The choice of derivatives to be made was based upon (i) known biologically active compounds (e.g. aloe-emodin) and (ii) interesting biologically active functional groups (e.g. amines). These aloin derivatives include aloe-emodin, rheinal, rhein and three amine derivatives. Homonataloin, an aloin-analogue, which was also isolated from A. marlothii, was synthetically transformed into nataloe-emodin. These two compounds serve as aloin structural analogues for the biological testing. Aloin and derivatives were characterised using NMR, HR-MS, UV and IR, which allowed for their unambiguous structural elucidation. Aloin and derivatives were all tested for (i) possible inhibition towards MMP-2 and MMP-9, which are the two most common MMPs in the blood, and (ii) antiplasmodial activity against chloroquine sensitive Plasmodium falciparum parasites. Doxycycline, a clinical tetracycline drug, was used as a reference compound for the biological assays, since it shares many common structural features with aloin and derivatives. 11-(Piperidin-1-yl)chrysophanol and 11-(morpholin-1-yl)chrysophanol proved to be the most potent selective MMP-2 inhibitors. 11-(Piperidin-1-yl)chrysophanol was also found to be the most potent against P. falciparum parasite, along with 11-(pyrrolidin-1-yl)chrysophanol. Aloin has been shown to be a cheap, easily obtainable lead compound that could facilitate the production of a range of powerful medicinal drugs. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

No abstract available. / Thesis (M.Sc.)-University of Natal, Durban, 2001.

This work is an account of investigations into the chemistry of one of the members of the Amaryllidacae family, Ammocharis coranica, and one of the members of the Fabaceae family, Sophora velutina. Chapter one is an account of the extractives from the bulbs of Ammocharis coranica. In all, twelve compounds, eight alkaloids and four cycloartane compounds have been isolated of which one alkaloid and one cycloartane compound have not been described previously. Plants belonging to the Amaryllidacae family have been used by traditional healers, especially in Africa, to treat a range of illnesses and diseases. The alkaloids isolated from these plants have been shown to exhibit responses to muscle stimulant, antiviral, antifungal, antiyeast, antimalarial, cytotoxic and antitumoural activities. Ammocharis coranica is used by the Zulu tribe in South Africa to treat any illness believed to be caused by witchcraft. Alkaloids from the three most common types among the isoquinoline group were found in this species. These are lycorine, 1-O-acetyllycorine, hippadine, acetylcaranine, and the novel 1-O- acetyl-9-norpluviine from the lycorine type, 6-α-hydroxypowelline from the crinine type and hamayne and crinamine from the haemanthamine type. Cycloartane compounds have not been reported previously from the Amaryllidaceae family. All four cycloartane compounds had a common side chain, containing an olefinic methylene group at position 24, but differed in their substituents at positions 3 and 4. These compounds were found to be 24-methylenecycloartan-3β-ol, cycloeucalenol, cycloeucalenone and the novel compound 4-methylenepollinastanone. Chapter two is an account of the extractives from the seeds of Sophora velutina. The seeds of other Sophora species have been used in traditional ceremonies by the Indians of the Southwest United States and adjacent Mexico because of their hallucinogenic activity. The seeds of Sophora velutina subsp. zimbabweensis found in Zimbabwe are suspected to have historically been used by the natives for their hallucinogenic properties. These plants have been known to contain several quinolizidine alkaloids, flavonoids and isoflavonoids. One alkaloid, N-methylcytisine and two isoflavones, pseudobaptigenin and calycosin, as well as the common phytosterol, β-sitosterol were isolated from the seeds of this species. N-methylcytisine is a common quinolizidine alkaloid, isolated previously from several Sophora species and pseudobaptigenin and calycosin are well known isoflavones, isolated previously from several species in the Fabaceae. / Thesis (M.Sc.)-University of Natal, Durban, 1999.

This thesis describes a phytochemical investigation of four medicinal plants, namely, Agave attenuata (Agavaceae), Balanites maughamii (Balanitaceae), Astrotrichilia parvifolia (Meliaceae) and Combretum fragrans (Combretaceae). Investigations of A. attenuata and B. maughamii were undertaken as biological studies have shown that these plants possess anti-bilharzial properties. Schistosomiasis is an important public health issue in South Africa and attempts to deal with infected rural communities have forced scientists to focus their attention on snail control using plant molluscicides. A. attenuata yielded two glycosides, timosaponin A III (compound I) and 5?-pregn-16-en-20one- 3?-O-tetrasaccharide (compound II), while a coumarin, scopoletin (compound III) and a sterol, stigmasterol (compound IV) were isolated from B. maughamii A dammarane, shoreic acid (compound V) was isolated from A. parvifolia, this formed part of an ongoing investigation into the Meliaceae of Madagascar. Plants of the family Combretaceae are widespread in Africa and are used by traditional healers for a wide range of illnesses. The leaves and bark are used abundantly, however, the winged fruits are never eaten as they are highly toxic to animals and humans. The leaf surface is covered with epidermal scale-like trichomes through which acidic triterpenoid mixtures are secreted. Six lupane-type triterpenoids were isolated from C. jragrans, namely, lupeol (compound VI), lupenone (compound VII), lupeol 3?- docosanoate (compound VIII), lupeol 3?-eicosanoate (compound IX) hennadiol (compound X) and 30hydroxylupenone (compound XI). All the above compounds were isolated by column chromatography and the structures were elucidated by means of NMR spectroscopy, mass spectrometry and infra red spectroscopy. / Thesis (M.Sc.)-University of Natal, Durban, 2000.

Momordica foetida Schum. & Sond. (Cucurbitaceae), locally known as iNtshungu, is widely used by the Zulu people of Natal-KwaZulu for the treatment of a variety of ailments. The dried leaves leaves and stems of this plant was subjected to soxhlet extraction by refluxing with hexane, chloroform and methanol successively. Thin layer chromatography of the chloroform extract of the leaves revealed a multiplicity of compounds. The chloroform extract was further partitioned with sodium hydroxide resulting in an organic and aqueous phase. The organic phase, containing extract A, afforded two compounds, viz. compounds 1 and 2. The basic aqueous fraction was neutralised and re-extracted with chloroform to give extract B, affording five compounds, viz. compounds 3,4,5,6 and 7. Structural elucidation was accomplished by techniques such as IH and 13C NMR spectroscopy, HETCOR, COSY, FTIR and High Resolution Mass Spectrometry. Compounds 1 and 2 were identified as cucurbitane triterpenoids known as momordicines which had been previously discovered in the related species of this plant, Momordica charantia L. The remaining five compounds were identified as novel compounds, although natural derivatives of compounds 6 and 7 had been isolated previously from Momordica charantia L. Compounds 3-7 were each isolated as an epimeric mixture but it was possible to select the resonances corresponding to the major epimer. These five epimers were respectively identified as 5, 19-epoxy-19(R)-hydroxy-25-methoxy-5β- cucurbita-6,23-diene-3β-ol [102], 5,19-epoxy-19(R),25-dihydroxy-5β-cucurbita- 6,23-diene-3β-ol [103], 5,19-epoxy-19(R)-methoxy-25-hydroxy-5β-cucrbita- 6,23-diene-3β-ol [104], 5,19-epoxy-25-methoxy-5β-cucurbita-6,23diene- 3β-ol [105] and 5,19-epoxy-19(R),25-dimethoxy-5β-cucurbita-6,23diene- 3β-ol [106]. Appropriate reactions were performed, where possible, on the compounds isolated in order to confirm their identity. / Thesis (M.Sc.)-University of Natal, Durban, 1994.

In this study two medicinal plant species, namely Artemisia afra Jacq. ex. Willd and Elytropappus rhinocerotis Less. (L.f) (= Dicerotamnus rhinocerotis Koekemoer), both belonging to the family Asteraceae, have been investigated and different compounds isolated and characterised. Both species are important plants used in traditional medicine in general in Africa and particularly in South Africa. A. afra, commonly called "African wormwood" is one of 400 species belonging to the genus Artemisia and it is the only one indigenous to Africa. E. rhinocerotis is one of eight Elytropappus species which are all restricted to the Cape floristic region. The aim of this study was to investigate the phytochemistry of these species. In total fifteen compounds were isolated and characterised. From the E. rhinocerotis extract, four known compounds, labdanolic acid, methyl labdanolate, 6, 7- dimethoxycoumarin and a sesquiterpene viridiflorol were isolated. These compounds were not previously reported from E. rhinocerotis. Two different chemotypes of A. afra were studied and eleven compounds were isolated. These compounds include sesquiterpenes such as taurin, artesin, maritimin, artemin, norsantolinifolide, santolinifolide A, and reynosin, a flavonoid, 5- hydroxy-7,4-dimethoxyflavone, a coumarin called scopoletin or 7-hydroxy-6- methoxycoumarin and other aromatic compounds such as p-hydroxyacetophenone, and 2,4-dihydroxy-6-methoxyacetophenone. Except for taurin, scopoletin and 5-hydroxy-7, 4- dimethoxyflavone , none of these other compounds has been reported previously from A. afra. This study has shown that A. afra contains a large number of sesquiterpenoids, mostly from the eudesmane-type. Structural elucidation of different compounds was performed using mainly NMR spectroscopy. Other methods used for identification include LC-MS and infrared spectroscopy. The major compound, labdanolic acid, is known to selectively inhibit cyclooxygenase-2, an enzyme associated with inflammation. The presence of labdanolic acid in the plant may account for its traditional use as an anti-inflammatory. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

Diarylheptanoids are a family of plant metabolites with a characteristic structure of two hydroxylated aromatic rings attached by a linear seven-carbon chain. Diarylheptanoids have mostly been isolated from plants belonging to the Zingiberaceae family. The South African medicinal plant Siphonochilus aethiopicus, more commonly known as ‘wild ginger’, also belongs to the Zingiberaceae family. One of the compounds isolated from this plant it a novel diarylheptanoid. In this study, the synthesis of this novel diarylheptanoid will be investigated. The targeted diarylheptanoid has two substituted phenyl rings attached by a seven-carbon aliphatic chain with two sterogenic centers and a carbon-carbon double bond. Osmiumcatalysed asymmetric dihydroxylation was used to generate the two stereogenic centres. The Horner Wadsworth-Emmons (HWE) reaction was investigated, in order to generate the trans-double bond on the seven carbon aliphatic chain. HWE reaction is a transselective reaction leading to the formation of only the desired isomer. The synthetic strategy used for the synthesis of the targeted diarylheptanoid is the C2-moiety + C5-moiety strategy. The C2-moiety is the phosphonate ester and the C5-moiety is the aldehyde for the HWE reaction. In this investigation we were able to successfully synthesis the required C2-moiety and the C5-moiety. Both the precursors were synthesised from commercially available starting materials, utilising functional group transformation reactions. However, modifications to the C5-moiety were made due to its instability under the HWE reaction conditions. When the C5-moiety was an aldehyde, decomposition was seen under HWE reaction conditions. Thus the C5-moiety was converted to the corresponding lactol and then subjected to the HWE reaction. Nevertheless, this reaction was not successful, thus we were not able to couple the two precursors to form the desired seven-carbon aliphatic chain. Even though the targeted diarylheptanoid was not successfully synthesised, the synthetic route developed in this investigation is not only viable to the target compound but is also versatile enough to allow the synthesis of its analogues. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.