Medicinal Foodstuffs. XX. Vasorelaxant Active Constituents from the Roots of Angelica furcijuga KITAGAWA : Structures of Hyuganins A, B, C, and D

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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-β-D-glucopyranoside), two acetylenic compounds [(-)-falcarnol and falcarindiol], 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.