Biology and Medicine

Abstract

Phytochemical Screening, Antioxidant, Anti-inflammatory, and Glucose Utilization Activities of Three South African Plants Used Traditionally to Treat Diseases

Oyinlola O. Olaokun, Nqobile M. Mkolo, M. A. Mogale and Piet H. King

Medicinal plants are important in the treatment of human diseases. The medicinal properties of plants are attributed to the presence of secondary plant metabolites. Polyphenols, particularly fl avonoids, are phytochemicals that possess antioxidant and anti-infl ammatory activity, and modulate pathways involved in obesity and glucose metabolism. In folk medicine, a single plant may be used to treat various diseases owing to the presence of phytochemical varieties in plants. In this study, the acetone leaf extracts of Curtisia dentata, Pittosporum viridifl orum, and Portulacaria afra were investigated for total polyphenol and total fl avonoid content as well as for anti-infl ammatory, antioxidant, and glucose utilization activities by using standard methods. The C. dentata extract exhibited the highest polyphenols (125.12 ± 2.18 mg/g GAE) and fl avonoids (27.69 ± 4.98 mg/g QE). The P. viridifl orum extract exhibited the strongest DPPH radical antioxidant activity (IC50 value=12.94 ± 1.09 μg/ml) and anti-infl ammatory activity by inhibiting 5-lipoxygenase activity (IC50 value 5 46.50 ± 4.54 μg/ml). All extracts enhanced dose-dependent glucose utilization activity of muscle cells and adipocytes. P. viridifl orum enhanced the highest glucose utilization of C2C12 muscle cells (67.34 ± 0.51%), while C. dentata enhanced the highest glucose utilization of 3T3-L1 adipocytes (63.72 ± 0.48%) at the highest concentration of 500 μg/ml, with no signifi cant difference (p<0.05). Polyphenols may be responsible for the observed 3T3-L1 cells glucose utilization activity of C. dentata. However, the polyphenols alone may not be responsible for the antioxidant, anti-infl ammatory, and C2C12 cells glucose utilization activity of P. viridifl orum. To our knowledge, this is the fi rst study to demonstrate the glucose utilization potential of the species of medicinal plants.