Abstract:
Diabetes and arthritis are the most common chronic diseases. Arthritis is the leading cause
of global disability and diabetes has become a major health problem which is increasing
rapidly. The purpose of the study was to document medicinal plants that are used to treat
and manage diabetes and arthritis by traditional medicinal practitioners around the Vhembe
District Municipality as well as to evaluate their in vitro efficacy. Traditional practitioners were
interviewed using semi-structured questionnaires. Seventeen plant species belonging to
fourteen different families were found to be used in the treatment of diabetes as well as
arthritis. Fabaceae family was dominating. Antioxidant, anti-inflammatory, cytotoxicity, alphaamylase
and alpha-glucosidase) of five plant species, (Bridellia mollis, Elephantorrihiza
burkei, Elaeodendron transvaalense, Senna petersiana and Searsia lancea) used
traditionally to manage diabetes were investigated using the standard in vitro procedures.
All extracts showed a good nitric oxide inhibition, with highest percentage inhibition found in
the highest concentration of 100 μg/ml. They all had good percentage cell viability at lowest
concentration which was comparable to quercetin. Only two plant extracts B. mollis (T2) and
E. transvaalense (T3) had lower than inhibition of quercetin at 25 μg/ml than at 12.5 μg/ml.
In vero cells low toxicity effect was observed at lowest concentration tested, and toxicity
increased with the increase in concentration. In bovine dermis cell line all plant extracts had
more cell viability at lower concentration than doxorubicin. Ethanol extracts of B. mollis and
S. petersiana, and ethyl extract of E. transvaalense had a good alpha-amylase inhibitory
activity with IC50 values 58.6, 81.9 and 131.5 mg/ml respectively. Hydro-ethanol, ethyl
acetate and ethanol extracts of E. burkei exhibited a significant alpha-glucosidase inhibitory
activity with IC50 values 56.9, 52.2 and 129.7 mg/ml respectively. Kinetic analysis revealed
non-competitive and un-competitive inhibitions of the plant extracts on alpha-amylase and
alpha-glucosidase enzymes respectively.
The information obtained showed that people in Vhembe District Municipality still rely on
medicinal plants to treat and manage diabetes and arthritis. All plant extracts were toxic to
both bovine dermis and vero cell lines. S. lancea (T5) was found to be the most toxic plant
extract. The observed good inhibitions of both alpha-amylase and alpha-glucosidase
enzymes by plant extracts of B. mollis, S. petersiana, E. transvaalense and E. burkei
validate their use in the traditional treatment of diabetes in the region to some extent.
Aqueous extracts of these medicinal plants should also be investigated because water is the
main solvent which is used by traditional practitioners in the preparation of their herbal
medicines.
