Medicinal foodstuffs. XX. Vasorelaxant active constituents from the roots of Angelica furcijuga Kitagawa: structures of hyuganins A, B, C, and D

From the methanolic extract with vasorelaxant activity obtained from Angelica furcijuga Kitagawa, four new khellactone-type coumarins, hyuganins A, B, C, and D, were isolated together with twelve known coumarins, two known acetylenic compounds, and a known lignan. The structures of hyuganins A, B, C, and D were determined on the basis of chemical and physicochemical evidence. Nine principal coumarins (hyuganin A, anomalin, pteryxin, isopteryxin, isoepoxypteryxin, praerosides II and IV, apiosylskimmin, (R)-peucedanol 7-O-beta-D-glucopyranoside), two acetylenic compounds [(-)-falcarinol and falcarindioll, and related compounds were examined for inhibitory activities on high concentration of K+ (High K+)- and dl-norepinephrine (NE)-induced contractions. The results indicate that the 3'- and 4'-acyl groups of khellactone-type coumarins are essential for the inhibitory activity on the contractions by High K+. Hyuganin A and anomalin showed inhibitory effects on High K+-induced contraction, but not on NE-induced contraction. Other active coumarins (pteryxin, isopteryxin, isoepoxypteryxin) and an acetylenic compound (falcarindiol) non-selectively inhibited both contractions by High K+ and NE.