A chemical compound from a tree used in popular traditional African medicine is being developed into a complementary treatment for diabetes at the University of Johannesburg (UJ). The tree is highly vulnerable to poaching throughout Southern Africa, and the focus of one of an enormous conservation project.

Walburgia salutaris trees contain several active chemical compounds in their leaves, roots and bark. Some of these have been developed into commercial products.

UJ’s Professor Mthokozisi Simelane and co-researchers first isolated a promising chemical compound, called iso-mukaadial acetate, from the bark of Warburgia salutaris trees.

Prof Simelane is a researcher in the UJ Department of Biochemistry within the Faculty of Science.

Bark from these trees have been used by various cultures, in a region stretching from South Africa to Malawi. Traditionally, these have been used to treat a variety of illnesses, including common colds, blocked sinuses, coughs and malaria.

The trees are called by many names. Amazwecehlabayo, isibhaha, manaka, molaka, mulanga, shibaha, muranga, and pepperbark are examples of names for the dried bark, stems and roots from mature Warburgia salturaris trees.

Traditional healers would mostly harvest sustainably from the protected tree species. However, with more people in cities, harvesting by poachers leave mature trees without bark, and the trees die as a result.

At one stage, the species was listed as Endangered by the International Union for Conservation of Nature (IUCN). Since then, several Southern African cultivation and large-scale conservation projects have managed to pull the species back to IUCN Vulnerable status.

Since discovering the compound, Prof Simelane published a follow-up study where it was used to treat rats with induced diabetes. In the study, some blood cell issues caused by diabetes appeared to be improved.

The iso-mukaadial acetate compound also helped with blood sugar control and insulin levels in rats when administered in lower doses.

While many people wish to lose weight, some people living with diabetes really need to gain weight to maintain their health. The research shows that iso-mukaadial acetate may be a potential treatment to improve body weight in humans.

“Diabetes can cause either weight loss or weight gain, depending on blood sugar control and treatment. At diagnosis, some patients may experience weight loss due to insufficient insulin. When insulin is lacking or not working effectively, glucose cannot enter cells properly, so the body compensates by breaking down fat and muscle for energy, leading to weight loss. In contrast, improved blood sugar control or the use of insulin therapy may sometimes lead to weight gain as the body is able to utilise glucose more effectively and reduce energy loss through urine.”

Currently, Prof Simelane and his team are working on the product development of iso-mukaadial acetate as a complementary medicine for the treatment of diabetes in South Africa. They have a licensing partnership with a pharmaceutical company, and are currently negotiating the licensing terms.

To develop the compound fully into a viable commercial complementary medicine, the researchers need sustainable sources of it. While the bark from mature trees is the most popular with users of traditional medicines from the tree, that source is also the most threatened.

A commercial grower in South Africa is currently supplying Simelane’s team with Warburgia plants, he says. The company has a bioprospecting permit, which is required in South Africa for commercial product development from traditional medicines using indigenous plants.

In a deeply rural area of South Africa’s KwaZulu-Natal province, Warburgia salutaris trees still grow naturally. Traditional healers have harvested the trees for their bark for centuries to treat villagers. Some of Simelane’s post-graduate students hail from the area.

“We are exploring the plant’s many medicinal properties in collaboration with experts in complementary medicine. Our primary goal is to ensure the continued existence of this plant for future generations, while also harnessing its potential for the advancement of complementary medicine,” concludes Simelane.