Abstract
BackgroundOxidative 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.MethodsThe 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.ResultsAll 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.ConclusionsResults 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.
Highlights
Oxidative stress predisposes the human and animal body to diseases like cancer, diabetes, arthritis, rheumatoid arthritis, atherosclerosis and chronic inflammatory disorders
Free radicals or reactive oxygen species (ROS) are highly unstable molecules produced by living organisms during normal cellular metabolism [1]
Chemicals and reagents The chemicals we purchased from different suppliers were: Linoleic acid (Merck, Darmstadt, Germany), xylenol orange, ferric chloride (Searle Company, England), foetal calf serum (FCS), penicillin/streptomycin/fungizone (PSF) and Dulbecco’s modified Eagle’s medium (DMEM) (Highveld Biological, South Africa)
Summary
Oxidative stress predisposes the human and animal body to diseases like cancer, diabetes, arthritis, rheumatoid arthritis, atherosclerosis and chronic inflammatory disorders. Free radicals or reactive oxygen species (ROS) are highly unstable molecules produced by living organisms during normal cellular metabolism [1]. Oxidative stress is the leading predisposing factor of diseases such as cancer, diabetes, arthritis, rheumatoid arthritis, neurodegenerative disorders, hypertension, atherosclerosis and chronic inflammatory disorders. Reactive oxygen species act by oxidising polyunsaturated fatty acids within cell membranes and lipoproteins via metal ion-dependent hydroxyl radical formation causing disruption of the cell membrane [3]. The antioxidant constituents of medicinal plants may contribute to the protection of humans and animals from a variety of metabolic and infectious diseases [2, 5]. The determination of antioxidant capacity is reaction-mechanism dependent and closely linked to the complex nature of phytochemicals [7]
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