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Prenylated Flavonoids from Epimedium koreanum Nakai and their Human Neutrophil Elastase Inhibitory Effects

Soo Min Lee , Yeong Hun Song, Zia Uddin, Yeong Jun Ban and Ki Hun Park

Division of Applied Life Science (BK21 plus), IALS, Gyeongsang National University, Jinju 52828, Republic of Korea

Abstract: Human neutrophil elastase (HNE) has been linked to immune system functions, including inflammation, as well as the development of skin wrinkles, suggesting that HNE inhibitors have many practical applications. In this study, the methanol extract of Epimedium koreanum Nakai contained potent HNE inhibitory flavonoids (1–4) with IC 50 values of 6.06–125.80 μM. Prenyl groups within these flavonoids were critical for the inhibitory effects. For example, epimedokoreanin B (1) (IC 50 = 6.06 μM) showed 6-fold higher efficacy than that of its parent luteolin (IC 50 = 36.01 μM). A similar trend was observed for compound 2 (IC 50 = 6.28 μM) and its parent, apigenin (IC 50 = 37.94 μM). Lineweaver–Burk plots showed that the compounds exhibit mixed-type inhibition. In a detailed kinetic study, compound 1 was assigned to mixed type I and exhibited the greatest binding to the free enzyme (K I = 11.7 μM, K IS = 40.9 μM).

Keywords: Epimedium koreanum Nakai; prenylated flavonoids; epimedokoreanin B; human neutrophil elastase . © 2017 ACG Publications. All rights reserved.