Anti-inflammatory and antioxidant activities of flavonoids from the flowers of <i>Hosta plantaginea</i>

Abstract

<i>Hosta plantaginea</i> was a traditional Chinese medicinal plant used to treat inflammation-related diseases with little scientific validation. Twelve flavonoids, including two new compounds namely plantanones A (1) and B (2), were isolated from the flowers of <i>Hosta plantaginea</i>. Their structures were elucidated by NMR and HRMS as well as comparison with literature data. All of the isolated compounds showed significant inhibitory activities against ovine COX-1 and COX-2 at a concentration of 50 μM, with inhibition ratios from 53.00% to 80.55% for COX-1 and from 52.19% to 66.29% for COX-2. Further detailed testing showed that compounds 1, 2, 4 and 12 inhibited the COX-1 and COX-2 enzymes with IC₅₀ values 12.90-33.37 μM and 38.32-46.16 μM, respectively. Moreover, the antioxidant effects of these isolates against DPPH free radical-scavenging were also evaluated <i>in vitro</i>, and a tight structure-activity relationship was discussed. Our results suggested that the anti-inflammatory and antioxidant activities of <i>H. plantaginea</i> flowers are partly attributed to these flavonoids.