Medicinal Plants Used for the Traditional Management of Diabetes in the Eastern Cape, South Africa: Pharmacology and Toxicology

The use of medicinal plants for the management of diabetes mellitus is on the rise in the developing countries, including South Africa. There is increasing scientific evidence that supports the claims by the traditional healers. In this review, we compare the families of previously reported anti-diabetic plants in the Eastern Cape by rating the anti-diabetic activity, mode of action and also highlight their therapeutic potentials based on the available evidence on their pharmacology and toxicity. Forty-five plants mentioned in ethnobotanical surveys were subjected to a comprehensive literature search in the available electronic databases such as PubMed, ScienceDirect, Google Scholar and Elsevier, by using "plant name" and "family" as the keywords for the primary searches to determine the plants that have been scientifically investigated for anti-diabetic activity. The search returned 25 families with Asteraceae highly reported, followed by Asphodelaceae and Alliaceae. Most of the plants have been studied for their anti-diabetic potentials in vivo and/or in vitro, with most of the plants having a higher percentage of insulin release and inhibition against carbohydrate digesting enzymes as compared with insulin mimetic and peripheral glucose uptake. Almost all the investigated plants also inhibit oxidative stress as part of their hypoglycemic activity with less toxicity. However, the isolation of their bioactive molecules is still lacking. This review provides a resource to enable thorough assessments of the therapeutic profiles of available medicinal plants used for the management of diabetes in the Eastern Cape, South Africa. Further studies such as the identification of the active ingredients of potent plants still need to be carried out; this may lead to new molecules in drug discovery and development.