Antioxidant and Antidiabetic Activities of Flavonoid Derivatives from the Outer Skins of Allium cepa L

Ngoc Khanh Vu, Chung Sub Kim, Manh Tuan Ha, Quynh Mai Thi Ngo, Se Eun Park, Haeun Kwon, Dongho Lee, Jae Sue Choi, Jeong Ah Kim, Byung Sun Min

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Abstract

The onion, known as the bulb onion or common onion, is not only a key ingredient in many tasty and healthy vegetarian meals but also many traditional medicines. Nine new flavonoids [cepaflavas A, B (5, 6), cepadials A-D (7-9 and 14), and cepabiflas A-C (10-12)] and six known compounds (1-4, 13, 15) were obtained from the outer skins of Allium cepa L. Among them, compounds 5, 6, and 9 might be artificial products formed during extraction and isolation. New compounds were structurally elucidated using various spectroscopy/spectrometry techniques, including NMR and HRMS, and computational methods. Their absolute configurations were determined using time-dependent density functional theory calculations, combined with ECD spectroscopy, optical rotation calculation, and statistical procedures (CP3 and DP4 analysis). The free radical scavenging assays revealed that the new compounds 10-12 possessed considerable antioxidant activities with IC50 values of 4.25-8.88 and 7.12-8.14 μM against DPPH and ABTS•+, respectively. Compounds 13-15 showed substantial inhibitory activities against both α-glucosidase and protein tyrosine phosphatase 1B (PTP1B), with IC50 values of 0.89-6.80 and 1.13-6.82 μM, respectively. On the basis of molecular docking studies, 13 and 15 were predicted to have high binding capacity and strong affinity toward the active site of PTP1B.

Original languageEnglish
Pages (from-to)8797-8811
Number of pages15
JournalJournal of agricultural and food chemistry
Volume68
Issue number33
DOIs
Publication statusPublished - 2020 Aug 19

Keywords

  • Allium cepa skins
  • antioxidant
  • kinetic
  • molecular docking
  • PTP1B
  • α-glucosidase

ASJC Scopus subject areas

  • Chemistry(all)
  • Agricultural and Biological Sciences(all)

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  • Cite this

    Vu, N. K., Kim, C. S., Ha, M. T., Ngo, Q. M. T., Park, S. E., Kwon, H., Lee, D., Choi, J. S., Kim, J. A., & Min, B. S. (2020). Antioxidant and Antidiabetic Activities of Flavonoid Derivatives from the Outer Skins of Allium cepa L. Journal of agricultural and food chemistry, 68(33), 8797-8811. https://doi.org/10.1021/acs.jafc.0c02122