27 CHEMICAL CONSTITUENTS OF ALNUS SPP. : CONSTITUENTS OF THE CATKIN OF ALNUS PENDULA
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Chemical constituents of Alnus sieboldiana which belongs to the same genus as A. pendula has been reported previously by the present authors. We now examined the isolation and structural elucidation of chemical constituents of A. pendula and the comparison between these plants from the viewpoint of chemotaxonomy. From the benzene extract of the viscous material of the catkin, a new ketone, 1, 7-diphenyl-1, 3-heptadien-5-one (m.p. 61.0-62.5℃), n-paraffins (C_<21>-C_<31>), α-olefines (C_<23>-C_<29>), β-amyrenone, taraxerone, cinnamaldehyde, benzylacetone, β-phenylethyl cinnamate, pinocembrin, pinostrobin, alpinetin, galangin, pinosylvin monomethyl ether, eugenol, chavicol, benzoic acid, cinnamic acid, and β-phenylpropionic acid were identified. All aromatic compounds isolated from A. peneula have one or two monosubstituted benzene ring as well as those of A. sieboldiana. This seems to indicate that these compounds were biosynthesized from routes of shikimic acid-cinnamic acid and shikimic acid-malonic acid.
