Chondrocyte Secretion of NO, ROS, GAG and PGE2 in Surface and Middle Porcine Articular Cartilage Is Altered by Aqueous Seed Extract of Bambara Groundnut (Vigna subterranea L. Vedc.)

In Africa, Bambara groundnut (BG) (Vigna subterranea L. Verdc.) is used both as a food legume and a medicinal plant. Traditional healers used the seeds of Bambara groundnut for treating diarrhoea, impotency, colon cancer, nausea, vomiting, malignancies, and inflammations caused by osteoarthritis. In humans, the proinflammatory cytokine, interleukin-1β (IL-1β), plays a major role in the aetiology of osteoarthritis as it induces the release of catabolic factors that contribute to cartilage degradation. The aim of this study was to evaluate the protective effects of lyophilised aqueous extract of BG on porcine articular chondrocytes, following cell stimulation with proinflammatory cytokine IL-1β (10 ng/ml) and addition of different concentrations of BG aqueous seed extract (12.5, 50 and 200 µg/ml) or quercetin (12.5, 50 and 200 µg/ml) as antioxidant. Measurement of nitric oxide (NO), reactive oxygen species (ROS) and prostaglandins (PGE2) using ELISA, fluorescent probe 2´-7´-dichlorodihydrofluorescin diacetate (DCFH-DA) and Griess reagent respectively showed that BG extract decreased the stable free radical DPPH in both the middle zone and surface zone chondrocyte cells, and inhibited the IL-1β-induced production of NO and ROS, which have harmful effects on porcine articular chondrocytes. However, the level of glycosaminoglycans (GAG) rose relative to the pure IL-1β treatment 72 h after the addition of BG crude extract or quercetin. These results suggest that BG crude extract has chondroprotective effect which can safeguard cells against inflammation during osteoarthritis and other inflammatory disorders.