Purpose: To evaluate the mechanism of antioxidant activity of the methanol extract of Codonopsis pilosula. (p < 0.05) Methods: Anti-oxidative properties were assessed by measuring free radical scavenging activity, nitric oxide (NO) levels, protein oxidation and reducing power, while the mechanism of antioxidative effect of Codonopsis pilosula extract was determined by measuring iNOS and COX-2 expression in lipopolysaccharide (LPS)-stimulated raw cells. Results: Codonopsis pilosula extract (CPE) exerted significant DPPH free radical and NO-scavenging activities. Protein oxidation was decreased by 30 % by the CPE (1mg/ml). The extract (1mg/ml) enhanced reducing power 16-fold (compared with control). LPS-induced production of iNOS was significantly inhibited by the extract (60 %), suggesting that it inhibits NO production by suppressing iNOS expression. However, LPS-induced production of COX-2 was not significantly

Yam saponins (dioscin, gracillin, protodioscin, and protogracillin) were analyzed with three different C18 columns at incremental column temperatures from 15 to 45°C to investigate the effect of temperature on the retention and resolution of yam saponins. At low temperature, yam saponins showed decreased retention times and improved resolutions in the C18 columns. In the Kinetex C18 column at 15°C, the four saponins achieved baseline separation (Rs > 1.5) within 30 min. Pulsed amperometric detection was used to identify saponins with high sensitivity. The limits of detection and quantification of saponins were 0.11-0.31 and 0.33-0.95 ng, respectively. The correlation coefficients ranged 0.9986-1.0000. Intra- and inter-day precisions were <4.2% of retention times and <9.5% of the calculated contents. Average recoveries ranged from 92.18 to 105.98%. Saponin contents in Dioscorea nipponica tubers and commercial yam foods were determined without sample purification or concentration. Among the ten commercial yam foods investigated, only three showed significant saponin contents.

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