Five new flavonoids and their pharmacological activities from Iris tenuifolia Pall.

Five new components including two new isoflavones, 5, 7, 2′, 3′-tetrahydroxy-6-methoxyisoflavone (1), 5, 7, 2′, 3′-tetrahydroxy-8-methoxyisoflavone (2), one flavonol 5, 3′, 4′-tetrahydroxy-7, 2′-dimethoxyflavonol (3), one flavanone (2S)-5, 7, 3′-trihydroxy-2′-methoxyflavanone (4), and one flavanonol (2R, 3R)-3, 5, 3′, 4′-tetrahydroxy-7, 2′-dimethoxyflavanonol (5), along with nine known flavonoids (6–14) were isolated from under ground parts of Iris tenuifolia Pall.. Their structures were elucidated by NMR and HRESIMS data and by comparison of CD spectra with compounds having similar structure. The separated compounds were evaluated for in vitro antioxidant activities by DPPH and ABTS. The α-glucosidase inhibitory activity of the compounds were evaluated with the pNPG method, the results indicated flavonoids were potential inhibitors of α-glucosidase. Moreover, in vitro anti-oxidative assay using flow cytometry indicated that compounds 1–5 showed strong oxidation resistance ability on C8D1A cells without affecting the cell viability.