MSc student (Food Science) at Stellenbosch University


  Study leaders: Professor Dalene de Beer & Professor Elizabeth (Lizette) Joubert


"We know that some honeybush species have anti-diabetic properties, but we have not yet identified all the phenolic compounds responsible for it."

Exploring anti-diabetic properties of honeybush

In my research project, I focus on the identification and isolation of phenolic α-glucosidase inhibitors in "unfermented" (green, unoxidised) Cyclopia subternata. These inhibitors prevent or decrease the activity of a group of enzymes involved in the digestion of carbohydrates in the human gut. Fermentation (high-temperature oxidation processing) decreases the phenolic content of honeybush, therefore "unfermented" honeybush is used to produce extracts for nutraceuticals. Nutraceuticals are plant extracts that offer health benefits beyond the basic nutrition provided by conventional food products.

In recent years, honeybush extracts have gained interest due to their anti-diabetic properties. Researchers from the Agricultural Research Council (ARC), in collaboration with South African Medical Research Council, have investigated the anti-diabetic properties of honeybush, including C. subternata ("bergtee" or "mountain tea").

In my research, extracts produced from "unfermented" C. subternata will undergo fractionation, a process used to separate groups of phenolic compounds with similar properties. These fractions will be analysed to identify those fractions that are the most potent to inhibit the α-glucosidase enzyme. The major compounds in these potent fractions will identified by using advanced techniques. 

Why it matters

Diabetes mellitus, also known simply as diabetes, is a common metabolic disease that causes high blood sugar levels. An important treatment option for diabetes entails delaying the absorption of glucose through the inhibition of α-glucosidase, an enzyme involved in the digestion of starch in the gut. Synthetic α-glucosidase inhibitors have been used for several years in the management of this type of diabetes, but many patients experience gastrointestinal side effects when taking this medication. To prevent dose-related side effects of these synthetic inhibitors, the search for natural alternatives to commercial inhibitors is increasing.

CDippenaar-small.jpgIn my research, I am focusing on the potential of honeybush tea to help control diabetes, in particular type 2 diabetes. By investigating phenolic compounds with α-glucosidase inhibitory activity in C. subternata, genotypes with high levels of potent compounds can be identified. This information will help to expand value-adding opportunities for the honeybush industry in terms of production of nutraceutical extracts.

About the student

Dippenaar obtained her BSc degree in food science from SU in 2019. She is currently an MSc student at SU and plans to graduate at the end of 2021.


Carla Dippenaar, an MSc student in food science at Stellenbosch University, is conducting research on the α-glucosidase inhibitory activity of phenolic compounds.