Thesis (MSc (Phytomedicine, Paraclinical Sciences))--University of Pretoria, 2007. / Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 52-57). Also available on the World Wide Web.

Thesis (M.Inst.Agrar.)(Food production and processing)--University of Pretoria, 2006. / Includes bibliographical references. Available on the Internet via the World Wide Web.

Made available in DSpace on 2015-03-03T11:52:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-08-21Bitstream added on 2015-03-03T12:07:38Z : No. of bitstreams: 1 000797448.pdf: 1448139 bytes, checksum: 48dfe16fa3be080667b00a8cda3a288e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Na busca por fontes alternativas de antimicrobianos, diversos autores tem explorado o uso de plantas medicinais para o tratamento de várias doenças. A atividade antimicrobiana de várias espécies de plantas como, Cordia verbenacea DC, Mikania laevigata Schultz Bip. Ex Baker e Psidium cattleianum, popularmente chamadas de erva-baleeira, guaco e de araçá, respectivamente, tem sido relatada contra diversos microrganismos orais. O objetivo do presente estudo foi avaliar o efeito antimicrobiano dos extratos hidroetanólico bruto e as suas respectivas frações aquosa, butanol, hexano e acetato de etila de Cordia verbenacea (CV) e Mikania laevigata (ML) e extratos aquoso e hidroetanólico de Psidium cattleianum (PC) contra Enterococcus faecalis, Pseudomonas aeruginosa, Actinomyces israelii e Candida albicans, sob condições planctônicas e de biofilme. Os microrganismos foram analisados em condições planctônicas por meio de ensaios para a determinação da concentração inibitória mínima (CIM) e concentração letal mínima (CLM), pelo método de microdiluição em caldo. Posteriormente, foram selecionados somente os extratos capazes de eliminar completamente cada microrganismo (CLM 100%), para a análise da atividade antimicrobiana em ensaios de biofilme. Os resultados mostraram que os valores de CIM e CLM variaram de 250 à 4000?g/ml. O biofilme formado por E. faecalis foi eliminado frente à ação dos extratos aquoso e hidroetanólico de PC e à fração acetato de etila de ML. A mesma fração de ML e o extrato hidroetanólico de PC também foram capazes de eliminar biofilme de P. aeruginosa. O mesmo ocorreu com as frações hexânicas de CV e ML e o extrato hidroetanólico de ML frente ao biofilme de A. israelii. Nenhum extrato/fração foi capaz de eliminar biofilme de C. albicans. Este estudo demonstrou o potencial antimicrobiano de extratos ou frações de Cordia verbenacea, Mikania laevigata... / Seeking for alternative sources of the antimicrobials, several authors have explored the use of herbal medicines for the treatment of diseases. The antimicrobial activity of various species of plants, such as Cordia verbenacea DC, Mikania laevigata Schultz Bip. Ex Baker and Psidium cattleianum, known as erva-baleeira, guaco and araçá, respectively, has been reported against several oral microorganisms. The present study aimed to evaluate the antimicrobial effect of Cordia verbenacea (CV) and Mikania laevigata (ML) hydroethanolic crude extracts and their fractions aqueous, butanol, hexane and ethyl acetate and aqueous and hydroethanolic extracts of Psidium cattleianum (PC) against Enterococcus faecalis, Pseudomonas aeruginosa, Actinomyces israelii and Candida albicans, under planktonic and biofilm conditions. The microorganisms in planktonic conditions were analyzed by determination of minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) assays using the microdilution broth method. Posteriorly, only the extracts that were able to totally eliminate each microorganism (MLC 100%) were selected for the antimicrobial activity analysis in the biofilm assay. The results showed that the MIC and MLC values ranged between 250 and 4000?g/ml. E. faecalis biofilm was eliminated by PC aqueous and hydroethanolic extracts and the ML ethyl acetate fraction. The same ML fraction and PC hydroethanolic extract were also able to eliminate the P. aeruginosa biofilm. The same occurred with the CV and ML hexane fractions and ML hydroethanolic extract against the A. israelii biofilm. None of the extracts/fractions were able to eliminate the C. albicans biofilm. This study confirmed the antimicrobial activity potential of Cordia verbenacea, Mikania laevigata and Psidium cattleianum, suggesting their use for endodontic purposes due to their effectiveness against pathogens associated with persistent or se...

M.Sc. (Chemistry) / The extraction of the atropine and scopolamine alkaloids from both Datura ferox and Datura stramonium was carried out in this study to investigate potential of these plants as a source of these alkaloids. Tropane alkaloids such as atropine occur naturally in many members of several plant families, especially the Solanaceae, Erythroxylaceae, Proteaceae and Convolvulaceae families. Hyoscyamine or its racemic mixture atropine is used as an antidote to organophosphate insecticides, or as a nerve agent to dilate the pupil for retina examinations. Scopolamine or hyoscine is used to treat motion sickness, among other uses. Tropane alkaloids are often difficult to synthesise, and their extraction from commercial sources is therefore of some commercial interest. A systematic study was carried by comparing different extraction methods for the efficiencies of tropane alkaloid (TA) extraction at ambient pressure. The two plants selected are already widely spread as weeds in many regions in South Africa and are therefore well adapted to the local conditions. Among the extraction methods, TA’s were extracted in their acidic form using dilute aqueous acids with 5% sulfuric acid giving the highest yield of both atropine and scopolamine. Alternatively, the TA’s were extracted in their basic form from the plant material using basified organic solvents. The overall yields obtained were not significantly different from those obtained by using dilute aqueous acids, with D. ferox giving approximately 0.24 % and 0.0028 % scopolamine and atropine, respectively. D. stramonium on the other hand gave approximately 0.037 % and 0.002% atropine and scopolamine, respectively. Different plant parts were also tested in order to determine if there was an advantage in extracting the tropane alkaloids at a particular time in the growth, but concluded that the best option was to extract the seeds for various reasons such as the presence of relatively less chlorophyll...

Advanced pancreatic cancer (APC) has a poor prognosis due to the high degree of resistance after systemic chemotherapy. Celastrol (CSL), a quinone methyl triterpenoid monomer extracted from Tripterygium wilfordii Hook F, exhibits superior antitumor activity on pancreatic cancer (PC) both in vitro and in vivo. In addition, CLS counteracts multiple mechanisms involved in multi-drug resistance (MDR) of PC cells. However, CSL induced toxicity to normal tissues (e.g. liver) is the major impediment to its clinical application. Thus, it is desirable to seek strategy to facilitate CSL selectively targeting PC tissues and simultaneously reducing its exposure to healthy tissues (e.g. liver). Aptamers are single-stranded oligonucleotides which specifically recognize and bind to targets by distinct secondary or tertiary structures. Nucleolin, a protein overexpressed on the plasma membrane of PC cells than that of normal cells (e.g. liver cell), which shuttle between cell surface, cytoplasm and nucleus, work as a cell surface receptor. Nucleolin aptamer is an anti-proliferative G-rich oligonucleotide with high affinity and specificity to nucleolin, which has been proved to be safe in clinical research. Then, nucleolin aptamer, as a target moiety, provide an approach to facilitate CLS selectively targeting PC cells. Taken together, our hypothesis is that the nucleolin aptamer modification could facilitate the conjugated CSL selectively targeting pancreatic cancer cells to achieve higher antitumor activity and less liver toxicity. In our study, CSL was conjugated to nucleolin aptamer to form Nucleolin Aptamer-Celastrol Conjugate (NACC). A CRO Aptamer-Celastrol conjugate (CACC) was also synthesized as a control for comparison. The water solubility of NACC was significantly higher than that of CSL. Then, the molecular weight of NACC was detected by ESI mass sepectrum (MS). The anti-proliferative efficacy of NACC was higher than CSL in vitro. NACC could selectively bind to PANC-1 cells over normal liver cells. The cellular uptake of NACC by PANC-1 cell was stronger than CSL. Moreover, NACC could be taken up by PANC-1 cells mainly via macropinocytosis. Tissue distribution study revealed that NACC could selectively accumulate in pancreatic tumor tissue and reduce the distribution in liver in vivo. In addition, NACC demonstrated higher antitumor activity and less liver toxicity in vivo, compared with CSL and CACC. The above results revealed that the nucleolin aptamer modification could facilitate the conjugated CSL selectively targeting PC cells to achieve higher antitumor activity and less liver toxicity.

Magister Scientiae - MSc / 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 / South Africa

Medicinal plants are the focus of intense study, in particular whether their traditional uses are supported by real pharmacological effects, or merely based on folklore. Piper capense L.f. (Piperaceae) is used traditionally for the treatment of infectious diseases, and has the potential to be a source of novel antimicrobial compound(s). Crude solvent extracts (water, methanol, hexane and acetone) and sequentially extracted subfractions of the root-bark of P. capense were prepared, of which the hexane-soluble subfraction MsAsHs was identified as the most promising antimicrobial subfraction. Phytochemical analyses of the various extracts and subfractions using TLC with numerous mobile phases and compound selective visualising reagents revealed the presence of quinones in all of the crude solvent extracts. Alkaloids, lipids/sterols/steroids, phenolic compounds and amino acids/peptides were detected in select subfractions. Gradient reverse phase HPLC analyses using 0.1% formic acid and methanol indicated three major peaks in MsAsHs. IR spectroscopy indicated that carbonyl and hydroxyl functional groups, and aromatic characteristics were present in the major compound present in MsAsHs. Further analysis using targeted LC-MS Q-TOF and quadrupole LC-MS/MS analyses indicated an empirical formula of C11H8O3. This formula was confirmed for the isolated compound by GC-MS (HP5-MS column) that identified the compound as 5-hydroxy-2-methyl-1,4-naphthoquinone (C11H8O3 MW: 188.18) with 98% certainty using the database. Although 5-hydroxy-2-methyl-1,4-naphthoquinone (also known as plumbagin) is well-known, this is the first time that the presence of this compound is reported in the Piper genus. Antimicrobial activities of P. capense root-bark extracts and the subfractions were determined against Gram-negative and Gram-positive bacteria and a yeast strain using the disk diffusion and broth micro-dilution assays. Antimicrobial activity was observed against Gram-positive bacteria, Gramnegative bacteria as well as a yeast strain, indicating broad spectrum activity. The antimicrobial activities of the crude solvent extracts decreased in the order: acetone > methanol > hexane > water. The MsAsHs subfraction demonstrated the highest antimicrobial activity with an MIC of 29 μg/ml against both Staphylococcus aureus (ATCC 12600) and Candida albicans (ATCC 10231). HPLC eluents of this subfraction that were collected in a drop-wise fashion onto silica TLC plates and assayed by bioautography, indicated that the major compound eluting at 13.6 minutes accounted for most of the antimicrobial activity. Antioxidant activity was observed for the crude water extract, crude methanol extract, crude acetone extract, MsAsAs subfraction as well as the MsAsHs subfraction. Cytotoxicity against mammalian cells in culture was observed for the crude methanol extract, crude acetone extract, crude hexane extract and the MsAsHs subfraction when determined using C2C12 cells as well as resting and PHA stimulated lymphocytes. Stability testing of the MsAsHs subfraction revealed that the antimicrobial compounds found in this subfraction appear to be stable up to 30 days at both 25°C and 40°C when assayed against S. aureus. However, when assayed against C. albicans, there was an increase in antifungal activity from 29 μg/ml to < 7 μg/ml after 30 days at both temperatures tested. This study provides scientific support for the ethnomedical use of the rootbark of P. capense as an antimicrobial. To date, the presence of plumbagin has not been reported in any other plant in the Piper genus. Due to the significant cytotoxic activity against mammalian cells reported in the current study and the mechanism of action of plumbagin, the therapeutic potential of P. capense extracts is very limited due to non-selective cytotoxicity, despite its marked antimicrobial activity. / Dissertation (MSc)--University of Pretoria, 2011. / Pharmacology / unrestricted

Magister Scientiae - MSc / Early man dabbled with the use of plant extracts to cure ailments. This practice has been passed down from generation to generation and today more than 50% of the world'sdrugs are natural products or derivatives thereof. Scientists have thus established a branch of research called natural product research. This branch of research involves the identification and purification of secondary metabolites with a specific biological activity. The methodology involves the screening of plant products for a specific biological activity, purification of the biologically active natural product by separation technology and structure determination. The biologically active natural products is then further scrutinized to serve as a novel drug or lead compound for the development of a novel drug. This research exploited this research methodology. / South Africa

Yes / This study describes the screening of 13 commercially-available plant extracts for pharmacological activity modulating vascular function using an endothelial cell model. A French maritime pine bark extract (FMPBE) was found to have the greatest effect upon nitric oxide availability in control (181% ± 36% of untreated cells) and dysfunctional cells (132% ± 8% of untreated control cells). In healthy volunteers, the FMPBE increased plasma nitrite concentrations 8 h post-consumption compared to baseline (baseline corrected median 1.71 ± 0.38 (25% IQR) and 4.76 (75% IQR) µM, p < 0.05). This was followed by a placebo-controlled, healthy volunteer study, which showed no effects on plasma nitrite. It was confirmed that different batches of extract had been used in the healthy volunteer studies, and this second batch lacked bioactivity, assessed using the in vitro model. No difference in plasma catechin levels was seen at 8 h following supplementation between the studies (252 ± 194 nM versus 50 ± 64 nM, p > 0.05), however HPLC-UV fingerprinting showed that the new batch had a 5-15% in major constituents (including procyanidins A2, B1 and B2) compared to the original batch. This research describes a robust mechanism for screening bioactive extracts for vascular effects. It also highlights batch variability as a significant limitation when using complex extracts for pharmacological activity, and suggests the use of in vitro systems as a tool to identify this problem in future studies.