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 C
23H
24O
11⋅2H
2O; [α]
D23 -70.8°. Hydrolysis with conc. hydrochloric acid afforded 1 mole each of a genin as slightly yellow needles, m.p. 257°, C
15H
8O
4(OCH
3)
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
maxEtOHmμ (log): 279 (4.24), 336 (4.42). Hydrolysis of permathylated cirsimarin with 10% sulfuric acid affords colorless needles, m.p. 228° C
15H
7O
3(OCH
3)
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.
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