Five New Isoprenoid-substitued Flavonoids, Kanzonols F - J, from Glycyrrhiza uralensis

Abstract

Anew isoprenoid-substituted pteracarpan derivative, kanzonol F, a new isoflavanone derivative, kanzonol G, and three new isoflavan derivatives, kanzonols H, I, J, were isolated from Glycyrrhiur uralensis.These structures were elucidated with spectroscopic andlor chemical methods.Licorice, the roots and stolons of various species of Glyqwhiur (Leguminosae), has been used for a long time as one of the most important crude drugs.The commercial Chinese licorice imported to Japan is generally classified to three kinds, i.e. the northeastern liwrice (Touhoku Kanzoh in Japanese), the northwestern licorice (Seihoku Kanzoh in Japanese), and Xinjiang licorice (licorice from Xmjiang Uegur Autonomous Region of China, Shinkyo Kanzoh in Japanese).In the earlier papers, we reported the structures of isoprenoid-substituted flavonoids from the northwestern l i c o r i ~? ~ and Xinjiang licorice.'In the continuous research of commercial Chinese licorice, we examined the northeastern liwrice (G.uralensis ) imported from China.In this paper, we report five new isoprenoid-substituted flavonoids, named kanzonols F ( I ) , G (2). H (3), I (4), and J (9, along with four known compounds, 1-methoxyficifolinol(6)~ liwricidin (7),' licorisoflavan A (8),',* and glyasperin D (9),7,8 from the licorice.Kanzouol F (I), C26HZ8o5, [UID -119', was negative to methanolic ferric chloride test.The uv spectrum of 1 resemblesthe spectra of pterocarpan derivatives, such as 1-methoxyficifolinol ( 6 ) 6 The ' H nmr spectrum of 1 showed characteristic signals of pterocarpan, i.e. 6 3.45 (m, H-6a), 3.58 (t, H-6), 4.19 (ddd, H-6), and 5.62 (hr d, H-lla), along with signals of protons of a prenyl group, protons of a 2,2-dimethylpyranring, protons of a methoxyl group, and three singlet aromatic protons.These spectral data suggested that the compound (1) was monocyclized compound of 1-methoxyficifolinol(6).The presence of the methoxyl group at 1-position was 'Ihble 1. 13c nmrdataof 1 -3, 5 -7,lO and 11 in a t o n e d 6