薬用資源の研究 (第20報)

おうばこの葉の成分について

抄録

Pale yellow microneedles, m.p. 214° (decomp.), were isolated in 0.01-0.02% yield from the fresh leaves of Plantago (Plantago asiatica L.). This substance corresponds to the molecular formula of C₂₁H₂₀O₁₁⋅5H₂O, and colors brownish violet to ferric chloride, orange to yellow with magnesium and hydrochloric acid, and yellowish brown to yellow with zinc and hydrochloric acid. Its hydrolysis with 350% hydrochloric acid produced one mole each of scutellarein and glucose. The position of glucose bonding was proved to be 7, since complete methylation of the glycoside with diazomethane and subsequent hydrolysis afforded scutellarein 4′, 5, 6-trimethyl ether, m.p. 196-197°. This glycoside is therefore scutellarein 7-glycoside and was named plantaginin.