In vitro and in vivo assessment of inhibitory effect of stevioside on pro-inflammatory cytokines

OBJECTIVE Stevioside is a natural non-caloric sweetener which has been reported to have anti-inflammatory activity. The aim of the present study was to examine in vitro and in vivo effects of stevioside on rats plasma levels of tumor necrosis factor- α (TNF-α), interleukin-1β (IL-1β), TNF-α and IL-1β release from lipopolysaccharide(LPS)-stimulated rat peripheral blood mononuclear cells (PBMCs). MATERIALS AND METHODS Male wistar rats weighing between 170-220 g were given stevioside (0, 500 and 1000 mg/kg BW/day) for 6 weeks. Mononuclear cells were separated from peripheral blood samples. TNF-α and IL-1β levels in plasma and the release of TNF-α and IL-1β from PBMCs were determined using rat enzyme-linked immunosorbent assay (ELISA) kits. RESULTS Plasma levels of TNF-α and IL-1β were found to be non-detectable in control and groups treated with 500 and 1000 mg/kg of stevioside. Regarding TNF-α release from LPS-stimulated PBMCs, rats that were orally fed with 500 and 1000 mg/kg of stevioside were significantly different (p<0.05) from those in LPS-treated control group (186.8+18.6 and 151.4 + 15.4 vs 248.6+21.4 pg/ml). Additionally, IL-1β levels in rats treated with 500 and 1000 mg/kg of stevioside were significantly different (p<0.05) from those in LPS-treated control group (220.0+12.1 and 158.1 + 22.6 vs 294.4+16.1 pg/ml). CONCLUSION Consumption of stevioside has an inhibitory effect on the release of TNF-α and IL-1β from LPS-stimulated PBMCs in rats.