The anti-arthritic, anti-inflammatory, antioxidant activity and relationships with total phenolics and total flavonoids of nine South African plants used traditionally to treat arthritis

ILE is a PhD student in the Phytomedicine Programme. JPD (PhD) is a post-doctoral fellow in the Phytomedicine Programme. FSB (PhD) is Senior Lecturer and mentor in the Phytomedicine Programme. LJM (PhD) is an Associate Professor and the current leader of the Phytomedicine Programme. JNE (DSc) is a Professor and the founder of the Phytomedicine Programme in the Department of Paraclinical Sciences of the Faculty of Veterinary Science, University of Pretoria.BACKGROUND : Oxidative stress predisposes the human and animal body to diseases like cancer, diabetes, arthritis, rheumatoid arthritis, atherosclerosis and chronic inflammatory disorders. Hence, this study seeks to determine the antioxidant, anti-inflammatory and anti-arthritic activities of acetone leaf extracts of nine South African medicinal plants that have been used traditionally to treat arthritis and inflammation. METHODS : The anti-inflammatory activity of the extracts was determined by investigating inhibition of nitric oxide production in lipopolysaccharide activated RAW 264.7 macrophages as well as 15-lipoxygenase enzyme inhibition. An anti-protein denaturation assay was used to determine the anti-arthritic properties of the extracts. The antioxidant activity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethyl-benzthiazoline-6-sulfonic acid) (ABTS) radical scavenging assays and ferric reducing antioxidant power (FRAP). The total phenolic and total flavonoid concentration of extracts were determined by using standard methods. RESULTS : All extracts inhibited nitric oxide production in a dose-dependent manner in the LPS-stimulated RAW 264.7 macrophages. Extracts of Maesa lanceolata and Heteromorpha arborescens inhibited NO production by 99.16 % and 89.48 % at a concentration of 30 μg/ml respectively. Elaeodendron croceum and Calpurnia aurea extracts had strong activity against 15-lipoxygenase activity with IC50 values of 26.23 and 34.70 μg/ml respectively. Morus mesozygia and Heteromorpha arborescens extracts had good in vitro anti-arthritic activity with IC50 values of 11.89 and 53.78 μg/ml, the positive control diclofenac sodium had IC50 value of 32.37 μg/ml. The free radical scavenging activity of the extracts in DPPH assays ranged between 7.72 and 154.77 μg/ml. Trolox equivalent antioxidant capacity (TEAC) and FRAP values ranged from 0.06 to 1.32 and 0.06 to 0.99 respectively. CONCLUSIONS : Results from this study support the traditional use of the selected medicinal plants in the management of arthritis and other inflammatory conditions. The free radical scavenging capacity of the extracts may be related to an immune boosting potential.The National Research Foundation of South Africa (Eloff IPPR 953991) and the University of Pretoria.http://www.biomedcentral.com/bmccom/plementalternmedam2016Paraclinical Science