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.

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

The wood, leaf and seed extracts of Apodytes dimidiata, Turraea floribunda and Turraea obtusifolia were examined. Two new limonoids belonging to the Toonafolin group were isolated from the seeds, two known havanensin-type limonoids were isolated from the leaves and both stigmasterol and sitosterol were isolated from the wood of Turraeafloribunda. Sitosterol as well as a limonoid which could not be characterised were isolated from the seeds, phytol, melianone and a protolimonoid similar to sapelin-F were isolated from the leaves and three protolimonoids: melianodiol, melianotriol and 7,8-dihydroturraeanthin 3-acetate were isolated from the wood of Turraea obtusifolia. An ester was isolated from the seeds of Apodytes dimidiata. Appropriate reactions were performed, where possible, on the compounds isolated. / Thesis (M.Sc.)-University of Natal, Durban, 1990.

Ledebouria zebrina and Scilla natalensis Planch were the two species investigated in this work. Ledebouria zebrina belongs to the Hyacinthaceae (Liliacea sensu lato) and to this date, the chemical composition of this species has not been investigated. Members of this family are found in southern Africa. The Ledebouria genus was formerly classified as part of the Scilla genus from which a large member of naturally occuring oxygen heterocycles known as homoisoflavanones have been isolated. In this work the bulbs of L. zebrina were investigated and five compounds were isolated. Three compounds were of the homoisoflavanone type while the remaining two belong to the eucosterol type triterpernoids. Scilla natalensis Planch also belongs to the Hyacinthaceae family. Previous chemical investigations of the bulbs of this plant yield two homoisoflavanones of the 3-benzyl-4- chromanone type. Members of this family are mostly found in the Eastern parts of the country, ranging from the Eastern Cape to Mpumalanga province including Lesotho and Swaziland. The bulbs of this plant were investigated and this yielded ten compounds. The structures of the isolated compounds were elucidated using spectroscopic methods. / Thesis (M.Sc.)-University of Natal, Durban, 2001.

No description available.

Adverse effects and increasing cost of therapeutic drugs have renewed an interest in the use of medicinal plant products for the treatment of a variety of chronic disorders. One such bioactive plant-derived compound is a pentacyclic triterpenoid, oleanolic acid (3ß-hydroxy-olea-12-en-28- oic acid, OA) present in herbs. OA possesses a variety of pharmaceutical activities and of interest in this study are the anti-diabetic properties. Diabetes is associated with disorders grouped as microvascular (retinopathy and nephropathy) and macrovascular (atherosclerotic) complications. Accordingly, this study further investigated the potential of OA in diabetes management by studying the effects of this triterpene on kidney function as well as proximal tubular Na+ handling in an effort to identify the site of action of OA. Furthermore, the study evaluated the effects of OA in kidney and liver cell lines to establish whether this triterpene exhibits any toxicity in these organs. OA was extracted using a previously validated protocol in our laboratory. Briefly, dried flower buds of Syzygium aromaticum were soaked in dichloromethane overnight, thereafter in ethyl acetate to obtain ethyl acetate solubles which contained a mixture of OA/ursolic and maslinic acid (MA). OA/MA mixture was subjected to column chromatograph and pure OA was obtained through recrystallization in methanol. The absolute stereostructure of OA was elucidated using 1H and 13C NMR spectroscopy and was comparable to previously reported data. In kidney function studies, various doses of OA (30, 60, 120 mg/kg, p.o.) were administered to male Sprague-Dawley rats twice (8h apart) every third day for five weeks. Rats administered deionised water served as controls. Measurements of body weight, food and water intake, blood pressure, Na+, K+, Cl-, urea and creatinine were taken 24 h from dosing. Renal clearance studies investigated the influence of OA on Na+ handling in the proximal tubule of anaesthetized rats using lithium clearance. Animals were given water with lithium (12mmol/l) for 48 hours following which they were anaesthetized and cannulated using a previously validated standard protocol that has been reported from our laboratories. After a 3½ h equilibration, animals were challenged with hypotonic saline for 4 h of 1 h control, 1½ h treatment and 1½ h recovery periods. OA was added to the infusate during the treatment period. In vitro effects of various OA concentrations (5, 10, 20, 40, 80 μmol/l) were investigated in HEK293, MDBK and HepG2cell lines. Cells were exposed to OA for 24, 48 and 72 h, thereafter, 3-4,5 dimethylthiazol-2-yl- 2,5diphenyltetrozolium bromide (MTT) and single cell gel electrophoresis (comet) assays were conducted. All data are presented as means ±SEM. OA significantly (p<0.05) increased urinary Na+ output from week 2 until the end of the experimental period in a dose independent manner. However, this OA-evoked natriuresis was not reflected in plasma collected at the end of the experiment as there was no change in plasma Na+ concentrations compared with control animals at the corresponding time. OA administration had no significant influence on K+ and Cl- excretion rates throughout the experiment. However, OA significantly (p<0.05) reduced plasma creatinine concentration with a concomitant increase in glomerular filtration rate (GFR). Furthermore, OA administration significantly (p<0.05) decreased mean arterial pressure from week 2 until the end of the experimental period. Intravenous infusion of OA at 90 ug/h for 1 ½ h induced a marked increase in urinary excretion rates of Na+. This increase was accompanied by concomitant increase in FENa proximal and FENa distal and FELi which persisted until the end of the experiment without any apparent changes in GFR. The cell viabilities of HepG2, HEK293 and MDBK cell lines were significantly increased after 24 h exposure, however, the viabilities of all the three cell lines dropped after 72 h exposure to values that did not achieve statistical significance in comparison to the respective controls. In addition, all OA-treated cells in the comet assay had intact DNA after exposure for 24, 48 and 72 h. Hence, the decrease in viability that was observed in the MTT assay after 72 h exposure could probably be attributed to the depletion of nutrients in the culture medium. The results of the present study, apart from confirming our previous observations of the natriuretic effects of OA in rats, indicate that this effect is in part mediated via the inhibition of proximal tubular Na+ reabsorption and increased Na+ secretion. We speculate that this increased Na+ secretion could have been due to increased tubular function and not to the toxicity of OA as indicated by MTT and comet assays. These findings suggest that OA does not exhibit toxicity in the kidney and the liver. / Thesis (M.Med.Sc.)-University of KwaZulu-Natal, Westville, 2012.

The Hyacinthaceae family is richly represented in southern Africa. Of the five subfamilies, three are found in southern Africa. These are the Urgineoideae (URG), Ornithogaloideae (ORN) and the Hyacinthoideae (HYA). The overview of Pfosser and Speta (1999), revealed chemotaxonomic trends at a subfamily level for the Hyacinthaceae family of the Flora of southern Africa region. Homoisoflavanones were found to define the Hyacinthoideae subfamily whilst the Ornithogaloideae subfamily and the Urgineoideae subfamily are defined by steroidal compounds namely, cholestane glycosides and bufadienolide glycosides respectively. Representatives of all three subfamilies were investigated phytochemically. From Eucomis comosa (HYA), five homoisoflavanones were isolated. Omithogalum tenuifolium (ORN) contained a spirostanol saponin of which the crystals were amenable to X-ray analysis. Evidence of a novel stereoisomer was obtained. Extraction of the bulbs of Galtonia princeps (ORN) led to the isolation of two cholestane glycosides, one known and one novel, and a homoisoflavanone. Two novel bufadienolides were isolated from Urginea Iydenburgensis (URG). Structures were elucidated on the basis of spectroscopic data and chemical evidences. Homoisoflavanones and related compounds were then screened for antibacterial and anti-inflammatory activity. Several compounds showed antibacterial activity against Staphylococcus aureus, a gram-positive bacteria. Inhibition of the inflammatory process in microsomal cells was first evaluated, followed by screening of specific inhibition of cyclooxygenase enzymes. These are membrane-associated enzymes occurring in different isoforms. High levels of anti-inflammatory activity were detected especially in microsomal cells. This biological information made it possible to rationalize the ethnomedicinal use of some of the plants from which the compounds were isolated. 15 Biological screening was followed by a computer-based quantitative structureactivity relationship (QSAR) study. This study produced five equations with significant prediction value of anti-inflammatory and antibacterial activity for homoisoflavanones and related compounds. The derived models also provided valuable parameter guidelines of those properties influencing the antiinflammatory and antimicrobial activity of the studied compounds. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2004.