薬用資源の研究 (第21報)

日本産あざみ属植物のFlavonoidsについて その3 はまあざみ葉の成分について

抄録

Dried leaves of Cirsium martimum MAKINO was extracted with methanol, methanol was evaporated from the extract, and a glycoside was obtained as almost colorless needles, m.p. 243° (melting once at 173-179°) in 0.2% yield. Its molecular formula agrees with C₂₃H₂₄O₁₁⋅2H₂O; [α]_D²³ -70.8°. Hydrolysis with conc. hydrochloric acid afforded 1 mole each of a genin as slightly yellow needles, m.p. 257°, C₁₅H₈O₄(OCH₃)₂, and glucose. The glycoside was named cirsimarin, and the genin, cirsimaritin.
Demethylation of cirsimaritin gives scutellarein and its permethylation of gives scutellarein tetranethyl ether, so that cirsimaritin is scutellarein dimethyl ether.
Decomposition of cirsimaritin with 3% hydrogen peroxide gives p-hydroxybenzoic acid, and that with 20% potassium hydroxide gives p-hydroxybenzoic acid and 4, 5-dimethoxyresorcinol.
Methylation of cirsimaritin with diazomethane affords a trimethyl ether, m.p. 1.83°, which agreed with scutellarein-4′, 6, 7-trimethyl ether, m.p. 183°, UV λ_max^EtOHmμ (log): 279 (4.24), 336 (4.42). Hydrolysis of permathylated cirsimarin with 10% sulfuric acid affords colorless needles, m.p. 228° C₁₅H₇O₃(OCH₃)₃.
Decomposition of this aglycone, m.p. 228°, with 3% hydrogen peroxide gives p-hydroxy-benzoic acid.
It follows, therefore, that cirsimaritin is scutellarein 6, 7-dimethyl ether. The structure of cirsimarin is cirsimaritin 4′-glycoside.