Thesis (DTech. degree in Crop Sciences) -- Tshwane University of Technology, 2011. / The genus Psoralea (tribe Psoraleae, family Leguminosae) is indigenous to the Cape Fynbos of South Africa and consists of 50 species that occupy different habitats, ranging from well-drained upland soils to creeks and permanent wetlands. However, little is known about their symbiosis, associated microsymbionts and or adaptation to the nutrient-poor, sandy, acidic soils of the Cape Fynbos. This study is the first to report the presence of calcium oxalate crystals in the outer cortex of P. pinnata and the occurrence of alkali and rare earth elements such as Sr, Rb, Zr and Y in tissue components of N2-fixing nodules (with unknown roles/functions).

>Magister Scientiae - MSc / Hyperpigmentation disorders such as melasma, freckles and black-pigmented spots on the surface of the skin are often a result of increased over production and accumulation of melanin pigments in the skin. In melanin biogenesis, tyrosinase is the key enzyme that catalysis the synthesis of melanin, thus the most effective and easiest way to reduce melanin synthesis is by inhibiting tyrosinase. There are a large number of reported tyrosinase inhibitors, their identification and isolation from natural sources is highly important because when natural tyrosinase inhibitors are identified in natural sources, their production is relatively low in cost. Tyrosinase inhibitors are highly sought in the cosmetic industry because of their skin – whitening effects. Most common used tyrosinase inhibitors are kojic acid (KA), arbutin, hydroquinone and ascorbic acid. However, these inhibitors have side effects and lack clinical efficiency. These facts led us to focus our research work on the exploration of natural tyrosinase inhibitors. Due to the therapeutic potential of medical plants researchers are not only concerned with validating ethnopharmacological usage of plants, but also with identification, isolation and characterization of bioactive components. Sutherlandia frutescens and Psoralea aphylla are both examples of indigenous fynbos species, which have been applied by indigenous people for the benefit of their medicinal properties.

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Good oral health has a major influence on the general quality of life and well-being. Several chronic and systemic diseases have been attributed to poor oral health. With the increasing incidence of oral diseases, the global need for alterative prevention and treatment methods and safe, effective, and economical products has expanded. There are many studies showed that Streptococcus mutans has been implicated as major etiological agent of dental caries. South African has very rich natural flora especially Cape region. Several South African medicinal plants have been used since immemorial time for treatment of different human pathologies including dental problems. The antibacterial activities of plants extracts have been recognized and documented scientifically during the last few decades. In this project we aimed at the screening of 31 South African plants randomly collected from Cape region for their antibacterial activity against Streptococcus mutans initially at two concentrations (500 and 100 µg/ml).MIC’s and MBC’s were determined for the active plant extracts, as well as the qualitative studies of the effect of the active extracts on the biofilm formation. The best or the most active safe plant (Psoralea fruticans) was submitted to chromatographic separation to isolate the bioactive compounds which could be responsible for such activity. Identification of the pure active compounds was carried out using different spectroscopic techniques. Finally the biological evaluation of the isolated pure compounds was measured against S. mutans and also the cytotoxicity studies in-vitro against normal cells lines was carried out.

The overall efficiency of plants to remediate soils contaminated by metals depends on their growth ability especially on soils with low-fertility. For twelve weeks, the ability of Psoralea pinnata to grow well and remove chromium and iron from artificially contaminated soil was tested. The concentrations of chromium and iron in two soils obtained from different sources namely, University of South Africa premises (US) and commercial potting soil (PS) were 80 ppm, 130ppm, 180ppm, 230ppm, 280ppm, 330ppm, 380pp, 430ppm and 480ppm. Psoralea pinnata was transplanted into the contaminated soils and the experiments were watered daily to maintain 70% moisture at field capacity in a greenhouse. Shoot height and root length of Psoralea pinnata before and after planting were measured. Other parameters that were measured were number of leaves, wet shoot and dry weights, and wet root and dry weights. The growth of Psoralea pinnata, after 12 weeks of experimentation was noticeably affected by the concentrations of chromium and iron in the soil. The percentage increases in shoot height of Psoralea pinnata in the PS Soil (C-PS, 48cm from initial shoot height of 12.6cm) treatments were generally higher than the increases in the US Soil (C-US, 45.2cm from initial shoot height of 12.8cm) treatments. Psoralea pinnata in the (US) treatments accumulated Fe (50.02 ppm) from the soil more than Cr (32.38ppm). In the (PS) treatments, Psoralea pinnata also accumulated more Fe (60.57 ppm) than Cr (38.34 ppm). In the experiments containing both Fe and Cr, the US treatments with 40 ppm each of Cr and Fe, chromium was initially mostly accumulated by Psoralea pinnata (68%). At higher concentrations (320 ppm) of the combined metals (Cr and Fe) treatment, more Fe (55%) was accumulated in Psoralea pinnata. This study however showed that Psoralea pinnata may not be an efficient phytoextraction plant for hyperaccumulation. / Environmental Sciences / M. Sc. (Environmental Management)

The overall efficiency of plants to remediate soils contaminated by metals depends on their growth ability especially on soils with low-fertility. For twelve weeks, the ability of Psoralea pinnata to grow well and remove chromium and iron from artificially contaminated soil was tested. The concentrations of chromium and iron in two soils obtained from different sources namely, University of South Africa premises (US) and commercial potting soil (PS) were 80 ppm, 130ppm, 180ppm, 230ppm, 280ppm, 330ppm, 380pp, 430ppm and 480ppm. Psoralea pinnata was transplanted into the contaminated soils and the experiments were watered daily to maintain 70% moisture at field capacity in a greenhouse. Shoot height and root length of Psoralea pinnata before and after planting were measured. Other parameters that were measured were number of leaves, wet shoot and dry weights, and wet root and dry weights. The growth of Psoralea pinnata, after 12 weeks of experimentation was noticeably affected by the concentrations of chromium and iron in the soil. The percentage increases in shoot height of Psoralea pinnata in the PS Soil (C-PS, 48cm from initial shoot height of 12.6cm) treatments were generally higher than the increases in the US Soil (C-US, 45.2cm from initial shoot height of 12.8cm) treatments. Psoralea pinnata in the (US) treatments accumulated Fe (50.02 ppm) from the soil more than Cr (32.38ppm). In the (PS) treatments, Psoralea pinnata also accumulated more Fe (60.57 ppm) than Cr (38.34 ppm). In the experiments containing both Fe and Cr, the US treatments with 40 ppm each of Cr and Fe, chromium was initially mostly accumulated by Psoralea pinnata (68%). At higher concentrations (320 ppm) of the combined metals (Cr and Fe) treatment, more Fe (55%) was accumulated in Psoralea pinnata. This study however showed that Psoralea pinnata may not be an efficient phytoextraction plant for hyperaccumulation. / Environmental Sciences / M. Sc. (Environmental Management)