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20 September 2024 | Story André Damons | Photo Supplied
zebrafish-blue-in-aquarium
Zebrafish blue in an aquarium.

A researcher from the University of the Free State (UFS) hopes to make living with epilepsy and other diseases of the central nervous system (CNS) easier by using South African plants extracts which may have anti-epileptic properties and testing them on zebrafish larvae.

Prof Anke Wilhelm, Associate Professor and Divisional Head of Organic Chemistry in the UFS Department of Chemistry, focuses her research on the isolation of active GABAergic compounds (substances that affect the brain’s GABA system, which helps control nervous system activity) by using a test that measures the movement of zebrafish larvae.

Even though obtaining regulatory approval for use as a treatment for epilepsy is a long and complex process, Prof Wilhelm hopes to contribute to the better pain management of people suffering from epilepsy and diseases of the CNS through an affordable alternative drug with less side effects.

The tests are done in a zebrafish bioassay (an analytical method to determine the potency of a substance by its effect on living animals) housed at the UFS’ Chemistry Department.

Why zebrafish larvae?

Prof Wilhelm, who is a National Research Foundation Y2-rated synthetic organic chemist, says zebrafish share about 70% of their genes with humans, and about 84% of human genes known to be associated with diseases have a counterpart in zebrafish. This makes them a valuable model for studying human biology and disease.

“Zebrafish are powerful tools for modelling a wide range of CNS diseases, contributing significantly to the understanding of disease mechanisms and the development of potential treatments,” she says. “Mood disorders, anxiety, insomnia, and attention deficit hyperactivity disorder (ADHD) are all diseases which may be studied through this bioassay.”

She explains that the zebrafish larvae are studied seven days after fertilisation in their bioassay. The larvae are incubated with the specific plant extract at a certain (non-toxic) concentration for three hours. Pentylenetetrazol (PTZ), a GABAA receptor antagonist that has been extensively used in rodent models for acute seizure and anxiety, is then administered to induce concentration-dependent seizures in the zebrafish larvae.

“GABA receptor antagonists are drugs that inhibit the action of gamma-aminobutyric acid, the chief inhibitory neurotransmitter in the mammalian central nervous system,” Prof Wilhelm says. “A specialised infrared camera is then used to track the movement of the larvae inside a chamber. The data is then converted into a graph which shows the movement of each larva over 30 minutes.

“If lowering of movement is observed at a specific concentration it means that the plant extract may have the potential to be used as an epileptic drug, since it has the ability to counteract the induced seizure in the larvae. This bioassay is extremely useful in drug discovery and toxicity screening of plant extracts.”

Zebrafish embryos, she says, develop quickly, with major organs forming within 36 hours of fertilisation. This rapid development allows researchers to observe the effects of experiments in a short period. The maintenance of a zebrafish model is less costly and labour-intensive than using a rodent model. “The use of zebrafish larvae allows for high-throughput screening due to their small size and transparency, which facilitates observation of CNS-related effects. Their genetic and physiological similarities to humans make them a valuable model for early-stage drug discovery.”

Potential uses

The next step in the research, according to Prof Wilhelm, is to identify a single compound from a natural source which may have potential anti-epileptic activity while causing less side effects than current drugs on the market. Researchers would then investigate the possibility of synthesising such a compound on a large scale, to eliminate the use of a natural resource and promote sustainability.

“Many plant extracts which I have screened show a synergistic effect in the zebrafish bioassay, meaning that the extract or the combination of compounds shows potential, but the isolated compounds are inactive. Even if a plant extract shows promise in preclinical and early clinical studies, obtaining regulatory approval for use as a treatment for epilepsy is a long and complex process.

“This includes demonstrating consistent efficacy, safety, and quality in large-scale clinical trials. One of the major challenges in using plant extracts is the lack of standardisation. The concentration of active compounds in plant extracts can vary depending on factors like the plant's growing conditions, harvest time, and extraction methods. This variability makes it difficult to ensure consistent efficacy and safety, therefore this is a time-consuming process.”

Green chemistry

After being approached by Dr Glen Taylor, Senior Director of the UFS Directorate Research Development (DRD), in 2017, regarding funding for Noldus Daniovision equipment, Prof Wilhelm received training from Prof Matthias Hamburger of the University of Basel in Switzerland on how to use such equipment. The larval zebrafish locomotive bioassay was established at the UFS Chemistry Department during 2017 and 2018 and now provides a third-stream income for the department, in conjunction with the Department of Genetics, where the adult zebrafish are housed.

Prof Wilhelm’s other research interests include green chemistry, food sustainability, and recycling. She is looking into green extraction techniques using non-conventional extraction methods to recover valuable bioactive compounds from agricultural and food residues. “Techniques like ultrasound, microwave-assisted extraction, and the use of deep eutectic solvents are becoming popular for their efficiency and alignment with circular economy principles.”

News Archive

Consumer Science at the UFS awards three PhDs
2015-07-08

Dr Gloria Seiphetlheng, Dr Natasha Cronje, Dr Ismari van der Merwe and Prof Hester Steyn.
Photo: Leonie Bolleurs

For the first time in its history, the Department of Consumer Science in the Faculty of Natural and Agricultural Sciences at the University of the Free State (UFS) earned three doctorates at one graduation ceremony this year. This week three PhDs were awarded to Ismari van der Merwe, Natasha Cronje, and Gloria Seiphetlheng at the Winter Graduation that took place on the Bloemfontein Campus.

Electrochemically-activated water is widely used in the food and other industries, due to its excellent environment-friendly properties. However, it is not used in the textile industry yet, because too little research has been done to determine the possible positive and negative impact it may have on textiles.

With the thesis, The evaluation of catholyte treatment on the colour and tensile properties of dyed cotton, polyester and polyamide 6,6 fabrics,  Dr Cronje, a lecturer in the UFS’s Department of Consumer Science, and Dr Seiphetlheng from the Serowe College of Education in Botswana,  provided major new information with the thesis, Anolyte as an alternative bleach for cotton fabrics. This information is essential when considering the application of catholytes and anolytes in the textile industry.

Electrochemically-activated water divides water in catholytes and anolytes. The anolyte part is used as a disinfectant and bleach. It is not really suitable for domestic use, as it can cause colour loss in coloured textile products. However, it can be used in the hospitality industry where white sheets, towels, etc., are used and washed on a regular basis.

The catholyte part of the water has properties similar to washing powder. It can also be used in the textile industry as washing liquid.

According to Prof Hester Steyn, Head of the Department of Consumer Science and supervisor of all three PhD candidates, this electrochemically-activated water is also very eco-friendly. “It has a short shelf life. If the electrochemically-activated water isn’t utilised, it returns to normal water that wouldn’t harm the environment. No water is therefore lost, and no waste products are released that would contaminate the environment,” she says.

Dr Van der Merwe’s research focused on Degumming Gonometa postica cocoons using environmentally conscious methods. A lecturer in the Department of Consumer Science, she demonstrated that simple and environmentally-friendly methods can be used with great success to procure wild silk from the cocoons of the Gonometa postica worms living in the camel thorn trees found in the Northern Cape and Namibia.

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