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SA plant extracts and zebrafish larvae could hold key to better epilepsy medication

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.”

The Noldus Daniovision equipment used by Prof Anke Wilhelm.

News Archive

UFS to investigate implementation of quality-monitoring system for SA food industry

2006-02-07

Some of the guests who attended the workshop were from the left Prof James du Preez (Chairperson: Department of Biotechnology at the UFS); Prof Lodewyk Kock (Head: South African Fryer Oil Initiative (SAFOI) at the UFS)); Mrs Ina Wilken (Chairperson: South African National Consumer Union (SANCU)); Prof Herman van Schalkwyk (Dean: Faculty of Natural and Agricultural Sciences at the UFS) and Mr Joe Hanekom (Managing Director of Agri Inspec).
Photo: Stephen Collet

UFS to investigate implementation of quality-monitoring system for SA food industry

The University of the Free State (UFS) will be investigating the implementation of a quality-monitoring service for the South African food industry.

This was decided during a workshop to discuss the external quality monitoring in the edible oil industry of South Africa, which was recently held at the UFS.

Major role players in the fast-food sector like Nando's, Spur, Captain
Dorego's, King Pie Holdings, Black Steer Holdings, etc and various oil
distributors like Felda Bridge Africa, Refill Oils, PSS Oils and Ilanga Oils attended
the workshop. Also present was Mrs Ina Wilken, Chairperson of the South African National Consumer Union (SANCU) and key-note speaker of this workshop. She represented the consumer.

These role players all pledged their support to the implementation of this quality- monitoring system for the whole food industry.

The decision to implement this system follows the various malpractices reported in the press and on TV concerning food adulteration (eg the recent Sudan Red Scare), misrepresentation (eg olive oil scandal exposed in 2001) and the misuse of edible frying oils by the fast-food sector.

“One of the basic rights of consumers is the right to safe food. Consumers must be protected against foods and food production processes which are hazardous to their health. Sufficient guarantee of the safety of all food products and food production processes should be implemented. It does not help to have adequate food standards and legislation and there is no manpower to do the necessary investigation or monitoring,” said Mrs Wilken.

The South African Fryer Oil Initiative (SAFOI), under the auspices of the UFS Department of Microbial, Biochemical and Food Biotechnology, currently monitors edible oils in the food industry and makes a seal of quality available to food distributors.

“Last week’s decision to implement the quality-monitoring system implies that we will now be involving also other departments in the UFS Faculty of Natural and Agricultural Sciences who are involved in various aspects of the food chain in an endeavor to implement this quality monitoring system,” said Prof Herman van Schalkwyk, Dean: Faculty of Natural and Agricultural Sciences at the UFS and one of the main speakers at the workshop.

Prof van Schalkwyk said that the main aim of such a system will be to improve the competitiveness of the South African food industry. “It is clear that the role players attending the workshop are serious about consumer service and that they agree that fraudulent practice should be monitored and corrected as far as possible. Although some of the food outlets have the capacity to monitor the quality of their food, it may not seem to the consumer that this is an objective process. The proposed external monitoring system would counteract this perception amongst consumers,” said Prof van Schalkwyk.

The workshop was also attended by representatives from SAFOI and Agri Inspec, a forensic investigation company collaborating with inter-state and government structures to combat fraud and international trade irregularities.

Agri Inspec has been working closely with SAFOI for a number of years to test the content of edible oils and fats. “Extensive monitoring and control actions have been executed in the edible oil industry during the past four years to ensure that the content and labeling of oil products are correct. Four years ago almost 90% of the samples taken indicated that the content differed from what is indicated on the label. This has changed and the test results currently show that 90% of the products tested are in order. However, to maintain this quality standard, it is necessary that quality monitoring and educational campaigns are continuously performed,” said Mr Joe Hanekom, Managing Director of Agri Inspec.

“The seal of quality presented by SAFOI should also be extended to include all the smaller oil containers used by households,” Mrs Wilken said.

The SAFOI seal of quality is currently displayed mainly on some oil brands packed in bigger 20 liter containers, which include sunflower oil, cottonseed oil, palm oil etc which are used by restaurants and fast food outlets. “Any oil type is eligible to display the seal when meeting certain standards of authenticity. In order to display the seal, the distributor must send a sample of each oil batch they receive from the manufacturer to SAFOI for testing for authenticity, ie that the container’s content matches the oil type described on the label. This is again double checked by Agri Inspec, which also draws samples countrywide from these certified brands from the end-user (restaurant or fast food outlets). If in breach, the seal must be removed from the faulty containers,” said Prof Lodewyk Kock, Head of SAFOI.

“It should however be taken into account that oils without a seal of quality from the UFS can still be of high quality and authentic. Other external laboratories equipped to perform effective authenticity tests may also be used in this respect,” said Prof Kock.

“It is also important to realise that any oil type of quality such as sunflower oil, cottonseed oil, palm oil etc can be used with great success in well controlled frying processes,” he said.

Further discussions will also be held with the Department of Health, the SA National Consumer Union and Agri Inspec to determine priority areas and to develop the most effective low-cost monitoring system.

More information on the UFS oil seal of quality and oil use can be obtained at www.uovs.ac.za/myoilguide

Media release
Issued by: Lacea Loader
Media Representative
Tel: (051) 401-2584
Cell: 083 645 2454
E-mail: loaderl.stg@mail.uovs.ac.za
6 February 2006

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