Thesis ( |b(MSc. (Biochemistry)) -- University of Limpopo, 2017 / Medicinal plants have been used as a key source for medication and they remain to provide new therapeutic remedies to date. Extracts of Olea europaea subspecies africana leaves are used extensively in South Africa to treat various diseases traditionally. The diseases have been noted to be associated with free radicals, bacterial infections, and inflammation. However, there is little information about the antioxidant, antibacterial, and anti-inflammatory activities of the leaves of this plant in literature and the cytotoxicity of the leaf extracts is still a concern. The information about the Isolated compounds is also minimal hence this study was aimed at filling in those gaps in relation to the traditional use of the leaves in southern Africa and subsequently isolating and identifying the active compounds using bioassay-guided fractionation. Preliminary screening of the crude extracts for antioxidant, antibacterial and antiinflammatory activities indicated that the extracts possessed all biological activities. The presence of major phytochemicals in the crude extracts was determined through the use of standard chemical methods and TLC analysis. The colorimetric methods (Folin-Ciocalteau and Aluminum chloride) were used for quantification purposes. TLC-DPPH assay was used to screen antioxidant activities of the crude extracts. The observed activity was quantified using the spectrophotometric method of DPPH and reducing power. The antibacterial properties of the leaf extracts were determined by direct bioautography and the serial broth microdilution assay using E. coli, P. aeruginosa, E. faecalis and S. aureus as test bacteria. Screening of the acetone crude extract for anti-inflammatory activities was done using the LPSstimulated RAW 264.7, cells where the inhibition of ROS generation was studied. MTT assay was used to determine the cytotoxicity effects of the leaves. Isolation of bioactive compounds started with serial exhaustive extraction, followed by column chromatography packed with silica gel. NMR analysis was conducted to identify the isolated compound. The results revealed the presence of tannins, terpenoids, steroids and flavonoids with the total phenolic (99.67 ± 2.52 mg of GAE/g) and tannin content (114.33 ± 9.02 mg of GAE/g) found in high amounts. All crude extracts exhibited antioxidant activities and the antioxidant activity quantified via the DPPH assay demonstrated to xxi have EC50 value of 1.05 ± 0.0071 mg/mL. The reducing capacity was found to be dose-dependent and great significance was seen at concentration 0.5 mg/mL to 1 mg/mL that was about 2/3 of that of L-ascorbic acid (standard) at a similar concentration. Screening of the crude extracts for antibacterial activity revealed that all crude extracts except n-hexane and water extracts, inhibited the growth of the tested bacteria on the previously developed TLC plates. The activity was seen as clear zones on the bioautograms. Serial broth microdilution assay indicated that dichloromethane, acetone and ethanol had average MIC values of 0.30, 0.32 and 0.35 mg/mL against all tested bacteria, respectively. Good anti-inflammatory activity of the crude extract was demonstrated at the highest concentration of 0.90 mg/mL. MTT assay indicated that the crude extract had no adverse cytotoxic effects. This was demonstrated by the LC50 values greater than 20 µg/mL and considered non-cytotoxic according to the National Cancer Institute (NCI). Isolation following the bioassay-guided-fractionation resulted in the selection of acetone extract to isolate the bioactive compounds from as it demonstrated good antioxidant and antibacterial activities. Fractionation of the compound by column chromatography yielded three combinations (pools) of fractions and of the three from which only pool 1 was considered for further fractionation. NMR spectra information identified the isolated compound as a mixture of ursolic acid (minor) and oleanolic acid (major). This compound had antibacterial and anti-inflammatory activities and no cytotoxic effects. The leaves of Olea europaea subspecies africana have been proven to possess antioxidant, antibacterial and anti-inflammatory properties. Evaluation of the biological activities of the crude extracts was to validate the use of the leaves traditionally to treat free radical and bacterial-related diseases and potential drug that are safe and has less side effects may be produced from the leaves. / National Research Foundation (NRF)

Thesis (M.Sc.) --University of Limpopo, 2008 / Senna species, a member of the Fabaceae family (subfamily Caesalpinaceae), is widely used traditionally to treat a number of disease conditions such as sexually transmitted diseases and some forms of intestinal complications. In this study the roots of Senna species, collected from Zebediela region of the Limpopo province (R.S.A), were ground to a fine powder and extracted with acetone by cold/shaking extraction method. The phytochemical composition of the extract was then determined by thin layer chromatography (TLC). The chromatograms were visualised with vanillin-sulphuric acid and p-anisaldehyde reagents. The total phenolic content of the extract was determined by Folin-Ciocalteu method and expressed as TAE/g of dry plant material. The extract was assayed for the in vitro anticancer activity using Jurkat T cells. The antioxidant activity was evaluated using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay and the antibacterial activity determined by both bioautographic and the microtiter plate methods. The acetone extract of the roots of Senna species inhibited the growth of Jurkat T cells in a dose- and time-dependent manner. The extract was shown to possess free radical scavenging activity and antibacterial activity against Pseudomonas aeruginosa, Enterococcus faecalis, Escherichia coli and Staphylococcus aureus with MIC values of 0.16, 0.078, 0.078 and 0.16 mg/ml, respectively. A compound with free radical scavenging activity was isolated from the acetone extract of the roots of Senna species through bioassay-guided fractionation. The isolated compound was identified as 1, 3-diphenol-2-propen-1-one. Thus, the study has systematically shown the biological activity of the roots of Senna species and the isolation and identification of the bioactive compound.

University of Macau / Institute of Chinese Medical Sciences

Thesis (M.Sc.)(Botany)--University of Pretoria, 2004. / Summary in English. Includes bibliographical references.

Thesis (B.S.)--University of Florida, 2000. / Submitted as part of the requirements for graduation with high honors from the University of Florida. Includes bibliographical references (leaves 137-139).

published_or_final_version / Pharmacology / Master / Master of Philosophy

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.

Chemoprevention may be defined as the inhibition, delay or reversal of carcinogenesis by dietary compounds or their derivatives. "Imifino" is a collective name for many wild plants used predominantly by rural people as herbs in cooking. Many of these herbs possess medicinal properties. As the rural population is at higher risk of exposure to dietary carcinogens, such as mycotoxins, this pilot study was undertaken to determine whether the Amaranthus lividus plant held potential for use in chemopreventive strategies. The plant leaves were extracted to obtain individual solvent fractions. Cytotoxic profiling of the fractions using the SNO oesophageal adenocarcinoma cell line and normal human lymphocytes was achieved using the methylthiazol tetrazolium salt bioreduction assay. The SNO cell line, the A549 lung adenocarcinoma cell line and normal human lymphocytes were utilised for the evaluation of the anti-mycotoxigenic potential of the plant fractions in combination with two important dietary carcinogens, aflatoxin B1 and fumonisin B1. A specific biomarker assay (the induction of reduced glutathione) was employed using the SNO cell line. Flow cytometry was also conducted to determine the apoptotic properties of the acetone fraction on normal human lymphocytes. The results of the anti-mycotoxigenic study showed that certain fractions did have protective effects against both of the carcinogens tested. In addition, these effects were noted in the two cancerous cell lines, which were of different tissue origin. None of the fractions tested were toxic towards the normal human lymphocytes. The glutathione assay indicated that certain acetone fraction dilutions were inducive to reduced glutathione production. This plant is a promising candidate for further investigation concerning chemoprevention and the rural community could be educated on the possible benefits of this herb. / Thesis (M.Med.)-University of KwaZulu-Natal, 2005.

Schistosomiasis is an important public health issue for rural communities located near,or around slow moving water bodies in the tropical and subtropical areas. Successful control of the disease involves multifaceted approaches, which include snail control, environmental sanitation, health education and chemotherapy. Although snail control might be an effective method of controlling schistosomiasis, there has been a general lack of control initiatives, largely due to the cost of available molluscicides. Plants offer a wide array of compounds which, on extraction, may show molluscicidal activity. If molluscicidal compounds that occur in indigenous plants can be extracted using local labour and simple technology, then there should be culturally acceptable and inexpensive molluscicides. The aim of this study was, therefore, to screen some Zulu medicinal plants for molluscicidal activity. We have also attempted to isolate the active chemical compounds from such plants. Aqueous and methanolic crude extracts of ten (10) Zulu medicinal plants, used for different medicinal and domestic purposes, were screened for molluscicidal activity on Biomphalaria pfeifferi and Bulinus africanas snails reared in the laboratory during the time of bioassay. Bayluscide® (niclosamide) was used as a positive control for comparison, while de-chlorinated tap water was used as the negative control. Six of the plants were not active against the snails. Extracts from four of the plants demonstrated weak to moderate molluscicidal activities. These plants are: (i) Sclerocarya birrea stembark, (ii) Psidium guajava (hybrid) leaves, (iii) Leonotis leonurus aerial parts and (iv) Ekerbegia capensis stem-bark. The LC50 values of the plant extracts were 78 ppm, 100 ppm, 398 ppm and 600 ppm respectively. Of the 4 plants that showed molluscicidal activity, S. birrea aqueous and methanol extracts were the most active against the snails, with LC50 values of 82 ppm and 78 ppm respectively. For the other plant extracts, only the methanolic extracts showed activity. Brine shrimp toxicity assay was performed with all the active extracts. Psidium guajava showed 10% survival of the shrimps at 1000 ppm, whereas no survival was observed for the other plant extracts at this concentration (1000 ppm). The results obtained in this study indicate that further studies have to be conducted, especially with S. birrea extracts, whose both aqueous and methanolic extracts showed significant activity against the snails. / Thesis (M.Med.Sc.)-University of Durban-Westville, 2002.