Specific immunomodulatory and secretory activities of stevioside and steviol in intestinal cells.
Stevioside, isolated from Stevia rebaudiana, is a commercial sweetener. It was previously demonstrated that stevioside attenuates NF-kappaB-dependent TNF-alpha and IL-1beta synthesis in LPS-stimulated monocytes. The present study examined the effects of stevioside and its metabolite, steviol, on human colon carcinoma cell lines. High concentrations of stevioside (2-5 mM) and steviol (0.2-0.8 mM) decreased cell viability in T84, Caco-2, and HT29 cells. Stevioside (2 mM) potentiated TNF-alpha-mediated IL-8 release in T84 cells. However, steviol (0.01-0.2 mM) significantly suppressed TNF-alpha-induced IL-8 release in all three cell lines. In T84 cells, steviol attenuated TNF-alpha-stimulated IkappaB --> NF-kappaB signaling. Chloride transport was stimulated by steviol (0.1 mM) > stevioside (1 mM) at 30 min. Two biological effects of steviol in the colon are demonstrated for the first time: stimulation of Cl(-) secretion and attenuation of TNF-alpha-stimulated IL-8 production. The immunomodulatory effects of steviol appear to involve NF-kappaB signaling. In contrast, at nontoxic concentrations stevioside affects only Cl(-) secretion.
Boonkaewwan
Chaiwat
C
Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
Ao
Mei
M
Toskulkao
Chaivat
C
Rao
Mrinalini C
MC
D018938:Caco-2 Cells; D045786:Diterpenes, Kaurane / Q000494:pharmacology*; D005960:Glucosides / Q000494:pharmacology*; D019073:HT29 Cells; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects* / Q000276:immunology*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013549:Sweetening Agents / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D045786:Diterpenes, Kaurane; D005960:Glucosides; D020672:I-kappa B Proteins; D016209:Interleukin-8; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D013549:Sweetening Agents; D014409:Tumor Necrosis Factor-alpha; C012043:stevioside; D000072000:NF-KappaB Inhibitor alpha; C012042:steviol