Abstract
The antiallergic activity of extracts of Naruto Kintoki sweet potato peel was enhanced after cooking the peel using three conventional methods. Using 400 µg/mL extracts, baking showed the highest suppression of β-hexosaminidase release (36.9%), followed by microwaving (41.9%) and boiling (64.2%). Significant suppression of β-hexosaminidase release from RBL-2H3 cells in response to Naruto Kintoki peel extract was attributed to compounds 9 (r = 0.91, p < 0.01) and 11 (r = 0.76, p < 0.05). UPLC/ESI-Q-TOF-MS analyses of compounds 5 and 8 clarified the existence of two sulfates of flavonol aglycones (3, 5, 3′-trihydroxy-7, 4′-dimethoxyflavone 3-O-sulfate and 3, 5-dihydroxy-7, 4′-dimethoxyflavone 3-O-sulfate). Baking the sweet potato peel changed compounds 5 and 8 to compounds 9 and 11 with enhanced antiallergic activity. Specifically, IC50 values changed from 11.0 µg/mL (5) to 4.1 µg/mL (9) and from 12.1 µg/mL (8) to 4.4 µg/mL (11). We found those four chemicals contributed to the observed antiallergic activity of Naruto Kintoki sweet potato peel extracts.
