From the 70% alcoholic extract of the air-dried bark of
Engelhardtia formosana Hay, yellow plates or needles, m.p. 177-180° (yield, 5.66-7.56%), and colorless needles, m.p. 295-296° (yield, 0.10-0.11%) were isolated and they were respectively designated as Glycoside A and Glycoside B. Hydrolysis of the Glycoside A yielded
l-rhamnose and two kinds of aglycones, yellow needles, m.p. 276-277°, and colerless silky needles, m.p. 231-232°, which were respectively designated as Aglycone A and Aglycone B. Aglycone A corresponds to the formula C
15H
10O
5 and gives a tetraacetate, C
15H
6O
6(COCH
3)
4, of m.p. 182°, a trimethyl ether, C
15H
7O
3(OCH
3)
3, of m.p. 146° by diazomethane (giving an acetate, C
15H
6O
3(OCH
3)
3(COCH
3), of m.p. 170°), and a tetramethyl ether, C
15H
6O
2(OCH
3)
4, of m.p. 157° with a large excess of diazomethane or by the application of dimethyl sulfate and 30% potassium hydroxide at a room temperature. Aglycone A was proved to be identical with 3, 5, 7, 4′-tetrahydroxyflavone (kaempferol), m.p. 277°, by mixed fusion with the sample prepared by the method of Robinson-Shinoda. Application of diazomethane to 5, 7-dihydroxy-3, 4′-dimethoxyflavone (III) yielded 5-hydroxy-3, 7, 4′-trimethoxyflavone (IV), m.p. 146-147° (giving an acetate of m.p. 170°) whose further methylation with dimethyl sulfate and alkali yielded 3, 5, 7, 4′-tetramethoxyflavone (V), m.p. 157°. (IV) was found to be identical with the trimethyl ether, and (V), with tetramethyl ether, obtained from Aglycone A.
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