Anti-inflammatory, anticholinesterase and antioxidant activity of leaf extracts of twelve plants used traditionally to alleviate pain and inflammation in South Africa.

ETHNOPHARMACOLOGICAL RELEVANCE Oxidative stress and inflammatory conditions are among the pathological features associated with the central nervous system in Alzheimer׳s disease. Traditionally, medicinal plants have been used to alleviate inflammation, pains and also other symptoms possibly associated with Alzheimer׳s disease. Therefore, the present study was designed to determine the in vitro anti-inflammatory, antioxidant and anticholinesterase activity of twelve South African medicinal plants traditionally used to alleviate pain and inflammation. MATERIALS AND METHODS Nitric oxide (NO) production in LPS-activated RAW 264.7 macrophages and 15-lipoxygenase (LOX) inhibitory assay were used to evaluate the anti-inflammatory activity. Acetylcholinesterase inhibition was assessed by using a modification of the Ellman׳s method. Antioxidant activity, total phenolic and total flavonoids contents were determined using standard in vitro methods. RESULTS The extract of Burkea africana had the highest anti-15-lipoxygenase activity with 85.92% inhibition at 100µg/mL. All the extracts tested inhibited nitric oxide (NO) production in a dose dependant manner in LPS-stimulated RAW 264.7 macrophages. However, extracts from Leucaena leucocephala, Lippia javanica inhibited the production of NO by 97% at a concentration of 25µg/mL. In addition, both Leucaena leucocephala and Englerophytum magaliesmontanum had strong activity against acetylcholinesterase with IC50 values of 118µg/mL and 160µg/mL respectively. Hight levels of phenolics and flavonoids were found in Leucaena leucocephala, Lippia javanica and Burkea africana. The correlation with antioxidant activities was not strong indicating that other metabolites may also be involved in antioxidant activity. CONCLUSIONS The results obtained in this study validate the use of leaf extracts of these plants in South African traditional medicine against inflammation. Extracts of these plants species might be of value in the management of various diseases emerging from oxidative stress and related degenerative disorders.