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Published on: December 3, 2019
Isolation and Caenorhabditis elegans lifespan assay of flavonoids from onion
You-Lin Xue1, Tomoyuki Ahiko, Takuya Miyakawa
1Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Abstract:
The main flavonoids were isolated from three selected onion cultivars. Three phenolic compounds were obtained by reverse-phase HPLC, and their structures were elucidated by multiple NMR measurements. There were two known compounds, quercetin and quercetin 3'-O-β-D-glucopyranoside (Q3'G), and one novel compound, quercetin 3-O-β-D-glucopyranoside-(4→1)-β-d-glucopyranoside (Q3M), which was identified in onion for the first time. These flavonoids were found to be more abundant in the onion peel than in the flesh or core. Their antioxidative activities were tested using the DPPH method, and their antiaging activities were evaluated using a Caenorhabditis elegans lifespan assay. No direct correlation was found between antioxidative activity and antiaging activity. Quercetin showed the highest antioxidative activity, whereas Q3M showed the strongest antiaging activity among these flavonoids, which might be related to its high hydrophilicity.
