Abstract:
INTRODUCTION : Traditional healing is often the preferred form of therapy especially in rural
and resource-limited communities. The extracts of plants are used to treat many diseases
such as arthritis and chronic pain. Four medicinal plant species, namely, Acokanthera
oppositifolia, Plantago lanceolata, Conyza canadensis and Artemisia vulgaris used in
Southern Africa to treat pain and inflammation-related diseases were selected for evaluation
in laboratory-based experiments.
METHODS : The selected plant species were evaluated for phytochemical content, antioxidant
and anti-inflammatory activities, as well as cytotoxicity effects against mammalian cells in
culture.
RESULTS : The results indicated that the n-hexane and chloroform extracts of P. lanceolata had
the best antioxidant activities with an IC50=0.41 μg/mL. Also, the acetone extracts of P.
lanceolata had 93.76% nitric oxide (NO) inhibition. However, the chloroform and n-hexane
extracts of C. canadensis produced NO inhibition of 98.53% and 99.2%, respectively, at 100
μg/mL with IC50=17.69 μg/mL. Furthermore, the ethyl acetate extracts also had promising
NO inhibitory activity (96.33%), but the cytotoxicity results with cell viabilities of 5.31%,
5.7% and 5.89%, respectively, suggested that the observed activity was due to a cytotoxic
effect. Acetone extracts of C. canadensis were also cytotoxic at 30 μg/mL with 6.07–6.67%
cell viabilities compared with the acetone extracts of P. lanceolata (99.57%).
CONCLUSION : The results partially validate the ethnomedicinal uses of the selected plant
species used for inflammation-related conditions. However, because some of the extracts had
potential cytotoxic effects, caution is advised in their use, especially those consumed orally.
