Faculty of Natural and Agricultural Sciences
School of Biological Sciences
Department of Biochemistry
Selected Highlights from Research Findings
The Department of Biochemistry's Complementary and Alternative Medicines (CAM) program, with the assistance of the University's Research Office, recently finalised a Research Sponsorship Agreement with the Japanese Corporation, Mitsui Norin.
Funds made available through this agreement and augmented by THRIP funding from the South African Department of Trade and Industry support a number of research programmes relevant to the tea industry. One of these projects focuses on the inactivation of enzymes in green tea.
The significance of this project stems from the fact that green tea is a natural source of flavonoids – chemical compounds that offer various health benefits because of their antioxidant properties.
Enzymes found in tea leaves remain active even after the leaves have been dried, slowly degrading the flavonoids. The beneficial qualities of green tea are thus directly correlated with the extent to which these enzymes can be inactivated during processing.
Researchers involved with the CAM program have succeeded in developing a novel process that is significantly more effective than any of its predecessors. This process comprises a number of steps, including blanching and steaming, and is currently being patented.
While green tea is good for people, it can be a repellent to some insects and fungi. This fact has prompted research on the use of green tea as an organic pesticide and fungicide.
As part of this research, a study was conducted to compare the fungicidal activity of a number of substances: a green tea extract, caffeine, a mixture of caffeine and green tea extract, and a selection of synthetic fungicides. These substances were tested for their ability to inhibit the growth of six fungi known to be responsible for severe losses in the vegetable industry.
Tomato, lettuce and cucumber plants were exposed to these fungi, and the percentage of infected plants was determined in each case by plating samples of their roots onto semi-selective media.
The study found that the mixture of caffeine and green tea extract produced the best overall results: it effectively controlled the growth of five out of the six fungal species.
In some instances, the test compounds produced better results than commercial fungicides administered at the recommended dose. The results of this study have led to the registration of a patent.
Black tea (including familiar brands such as Joko and Five Roses) has the same origins as green tea: the leaves of the evergreen shrub Camellia sinensis.
The difference between the two varieties of tea lies in the way the leaves are treated after they are picked. In the case of green tea, enzymes have to be inhibited so that the leaves retain as many of their natural qualities as possible.
In the case of black tea, however, enzyme activity is encouraged – a process loosely referred to as fermentation. Despite this fermentation process, black tea resembles green tea in that it contains flavonoids, although in reduced concentration.
The makers of Joko recently changed the design of its packaging to include information on the flavonoid content of this tea. The impact of this information is enhanced by comparing it with the flavonoid content of certain other products, such as orange juice.
In order to ensure the veracity of their advertising claims, the company commissioned the University to conduct regular tests on the concentration of flavonoids found in Joko tea and in the products with which it is compared on the packaging.
Dr Z Apostolides
Biochemistry
+27 (0) 12 420 2486
zeno.apostolides@up.ac.za
An NRF-funded project has been initiated that aims to identify the manner in which the expression of proteins and peptides in the hemolymph of Ornithodoros savignyi ticks is altered by injury or microbial challenge. Changes in the levels and structure of proteins are measured, and these are correlated with the immune induction process that is activated when a tick is injured or subjected to microbial infection.
Preliminary results indicate that immune challenge modulates the expression of numerous peptides and proteins. The hemolymph obtained from challenged ticks has also been found to inhibit the growth of the yeast Saccharomyces cerevisiae and of Gram (negative) Esherichia coli bacteria, indicating that the hemolymph contains anti-microbial components.
The isolation and characterisation of these novel entities are in progress. By extending the list of known immune-induced molecules, this research may lead to the development of more effective antimicrobial agents.
It could also result in the discovery of new targets for pesticide research and in the identification of antigens that may be developed further as anti-tick vaccines.
Prof AWH Neitz
Biochemistry
+27 (0) 12 420 2906
albert.neitz@up.ac.za
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