Anti-inflammatory effects of soyasapogenol I-αa via downregulation of the MAPK signaling pathway in LPS-induced RAW 264.7 macrophages.

The crude extract of soyasaponins was reported to possess anti-inflammatory activity. We determined the new purity group I saponin, I-αa and I-γa that was isolated from wild soybean (Glycine soja) in terms of its efficacy in protecting RAW 264.7 macrophages from lipopolysaccharide (LPS)-stimuli. Cells were treated with soyasaponin I-αa/I-γa (30-300 µΜ) and LPS (0.1 µg/mL) for 24 h. Soyasaponin I-αa inhibited nitric oxide (NO) production at 100 µg/mL, while soyasaponin I-γa demonstrated this effect at a higher concentration (200 µg/mL). The expression levels of iNOS and COX-2 enzymes were downregulated by both soyasaponins. Soyasaponin I-αa exerted its effect via the TNF-α and IL-1ß cytokines. However, soyasaponin I-γa only inhibited the expression of TNF-α. The inflammatory effect of group I soyasaponin was mainly mediated via the phosphorylation of the p38 and JNK proteins. Collectively, these results suggested the potential anti-inflammatory effects of soyasaponins.