Fernandes a, Cromarty D, Albrecht C, Jansen van Rensburg C. The antioxidant potential of Sutherlandia frutescens Journal of Ethnopharmacology. 2004;95:1-5.The use of botanical and herbal medicines as a complementary approach for the treatment of inflammatory diseases has been steadily increasing, possibly because of the adverse effects associated with the use of non-steroidal anti-inflammatory drugs. However, little is known about the mechanisms of action, appropriates doses, and toxicity of these herbal medicines. Sutherlandia frutescens is one of the best known multipurpose medicinal plants in Southern Africa, and it is used for a wide range of conditions (e.g., cancer, viral disease, and inflammation). This plant is indigenous to the Western Cape and Karoo regions of Southern Africa and is known there as 'cancer bush.' S. frutescens is rich in amino acids and pinitol, contains small amounts of saponins, and contains canavine, which is a non-protein alpha-amino acid with anti-tumor properties. Because the anti-inflammatory properties of various medicinal plants are thought to be due to their antioxidant activities, the authors of this study investigated the effects of a hot water extract of S. frutescens on lucigenin- and luminol-enhanced chemiluminescence on neutrophils stimulated by L-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP). In addition, the superoxide- and hydrogen peroxidescavenging activities of this plant were tested in cell-free systems.
Hot water extracts of S. frutescens subsp. microphylla were prepared by combining 1.0 g dessicated plant material and 20 mL of boiling water. Neutrophils were isolated from venous blood collected from healthy subjects. Oxidant production by FMLP-stimulated neutrophils was measured with the use of either luminol-dependent (for 150 seconds) or lucigenin-dependent (for 125 seconds) chemiluminescence. The oxidant-scavenging potential of the hot water extract was measured in cell-free systems: the superoxide anion and horseradish peroxidase/hydrogen peroxide systems. Cell viability in neutrophil suspensions incubated for 30 minutes at 37 degrees Celsius in various concentrations of the plant extract was also evaluated.
The luminol- and lucigenin-enhanced chemiluminescence responses of neutrophils stimulated by FMLP decreased significantly in a dose-dependent manner in hot water extracts of S. frutescens at concentrations as low as 10 mcg/mL. Hot water extracts of this plant inhibited superoxide-induced chemiluminescence at concentrations as low as 10 mcg/mL and inhibited horseradish peroxidase/hydrogen peroxideinduced chemiluminescence at concentrations as low as 0.62 mcg/mL. Furthermore, the hot water extract of S. frutescensup to concentrations of 40 mcg/mLhad no adverse effects on the cell viability of the neutrophil suspensions tested.
The results indicate that the hot water extract of S. frutescens studied exhibited significant superoxide- and hydrogen peroxidescavenging activities at concentrations as low as 10 mcg/mL in cell-free and in stimulated neutrophil systems. These scavenging properties may have accounted for the observed anti-inflammatory properties of the plant extract. The observed antioxidant activity may be related to the plant's constituent phenolic compounds (e.g., tannins and flavonoids). However, a better understanding of the extract's antioxidant activity requires further analysis to identify its active compounds. The authors conclude that both the reactive oxygen speciesscavenging properties of the extract and the extract's low toxicity 'suggest that this plant may be developed as an effective immunomodulator for the treatment of diseases associated with an overproduction of reactive oxidants by human phagocytes.'
Brenda Milot, ELS