Faculty of Natural and Agricultural Sciences
School of Biological Sciences
Department of Plant Science
Selected Highlights from Research Findings
Researchers in the Department of Plant Sciences have successfully isolated and identified anticancer, antiplasmodial, antiherpes, antityrosinase and antidiabetic activities in medicinal plants. Plants used in the study were collected based on phytochemical information and their ethno-botanical use. An extensive bioassay-guided fractionation of plant extracts led to the isolation of known and novel chemical compounds, which show potential for use by people with diabetes and with skin-hyperpigmentation problems. Two synthetically derived chemical compounds showed significant anticancer activity. The researchers found that these compounds were not toxic to lymphocyte cells. Pre-clinical studies are planned to test the anticancer compounds. All other tests that are necessary to develop products have been undertaken and samples are currently being considered for full human trial studies, which will be crucial for product development. Antidiabetic extracts have also shown good activity in mice in pre-clinical studies and a number of experiments are currently underway to substantiate the findings obtained thus far
Contact person: Prof JJM Meyer.
Researchers in the Department of Plant Sciences have successfully isolated and identified anticancer, antiplasmodial, antiherpes, antityrosinase and antidiabetic activities in medicinal plants. Plants used in the study were collected based on phytochemical information and their ethno-botanical use. An extensive bioassay-guided fractionation of plant extracts led to the isolation of known and novel chemical compounds, which show potential for use by people with diabetes and with skin-hyperpigmentation problems. Two synthetically derived chemical compounds showed significant anticancer activity. The researchers found that these compounds were not toxic to lymphocyte cells. Pre-clinical studies are planned to test the anticancer compounds. All other tests that are necessary to develop products have been undertaken and samples are currently being considered for full human trial studies, which will be crucial for product development. Antidiabetic extracts have also shown good activity in mice in pre-clinical studies and a number of experiments are currently underway to substantiate the findings obtained thus far
Contact person: Prof N Lall.
Differences in the primary structure of naturally occurring plant cystatins and their interaction with different cysteine proteases will provide valuable information for the specific interaction between the two proteins. A database containing all available information on structure, biochemistry, expression pattern and biotechnological application of all known cystatins is currently being developed. Comparison of the primary structures will reveal important information on the evolution of cystatins in plants. The database will also help to select the most suitable candidates for future biotechnological applications to prevent protein degradation during stress or senescence
Contact person: Prof KJ Kunert.
The aim of this research project was to create a better understanding of the structure/function relationship during the inhibition interaction of plant cystatins and cysteine proteases. Using advanced molecular modelling software, the three-dimensional structures of various plant cystatins, as well as mutated forms of these cystatins, are first solved. Using protein-protein docking, they are then bound to the cysteine protases and the specific interactions are analysed in terms of binding site interactions. This data is finally combined with biochemical data to form a model that will be used for the rational design and directed evolution of cystatins for improved and targeted activity against selected proteases in applications such as insect control or increased yield and production of recombinant proteins in plants
Contact person: Prof KJ Kunert.
Binding of cysteine proteases and their inhibitors (cystatins) seems to depend on the conserved regions in the first and second loop, as well as in the N-terminal. The objective of this research was to investigate the interaction between conserved regions of plant cystatins and cysteine proteases. Natural forms of rice (OsCYS1) and papaya (CpCYS1) cystatin, however, show significant differences in the amino acid sequence of the first loop. Substitution of the sequence in rice with the one found in papaya and vice versa will help evaluate the role of the conserved regions for their interaction with proteases. Detailed knowledge about the interaction between the two proteins will be needed for more target-specific application of cystatins in pest and pathogen management, as well as control of recombinant protein production in plants
Contact person: Prof KJ Kunert.
The non-expressor of pathogenesis-related gene 1 (NPR1) is an essential positive regulator of salicylic acid (SA)-induced pathogenesis-related (PR) gene expression and systemic acquired resistance (SAR), which is important in broad-spectrum pathogen resistance in plants. The research team has identified and isolated two novel full-length NPR1-like genes, MNPR1A and MNPR1B, from banana through the application of southern blot analysis, polymerase chain reaction (PCR) and rapid amplification of cDNA ends (RACE) techniques. Expression of the MNPR1 genes was directly related to PR gene expression known to be involved in fungal resistance after the treatment of banana plants with various elicitors. Expression of the two genes in various Arabidopsis mutants will, in particular, unravel the NPR1 protein activation process
Contact person: Prof KJ Kunert.
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