カワカワの成分(第二報) : メチスチチンの構造

抄録

Winzheimer (Arch. Pharm. 246, 338) assigned to methysticin the constitution (I) and observed also when treated with alkali it was saponified to methysticinic acid (II), which by the action of mineral acids gives methysticol (III). (I) [chemical formula] (II) [chemical formula] (III) [chemical formula] The authors (M. and Sh.) showed that when methysticin C₁₅H₁₄O₅ was warmed with aqueous caustic soda, an isomeric compound called isomethysticin (m.p.186°), is formed which is prcbably identical with the methysticinic acid of Winzheimer. By the action of mineral acids not only the isomethysticin, but also methysticin itself are converted into methysticol. An important fact hitherto overlooked is that methysticin is optically activ, whereas isomethysticin totally inactiv. On the basis of these observations the authors assigned to methysticin the constitution IV and to isomethysticin V. [chemical formula] Experimental. The material employed for this investigation was crude crystalline mixture containing mainly yangonine and methysticin. On recrystallization several times first from alcohcl and then from acetone pure methysticin m.p.135-137°was obtained. Analysis : -[table] Methoxyl number (Zeisel's method). [table] The optical rotation : [α]_<〓/D>=+94.30 (in 5% aceton solution). Action of aqueous Caustic Soda. (Isomethysticin). 10 grams of methysticin were mixed with 100 ccm of aqueous caustic soda (10%), warmed on a water bath for 7 hours, on cooling the reaction mixture the yellowish bright crystals of sodium compounds were 〓eparated, which were collected and agitated with dilute acetic acid (%) in order to isolate the reaction product. Recrystallized from acetone it was obtained in yellow needles melting and decomposing at 180° It is called isomethysticin. Analysis : - [table] Methoxyl number (Zeisel's method). [table] Optical rotation : - α=±0 Isomethysticin is insoluble in cold sodium carbonate solution, soluble in hot carbonate and on cooling a krystalline sodium compound separated, from which the isomethysticin again regenerated by means of acids. Action of dilute Sulphuric Acid on Methysticin. 5 grams of methysticin were mixed with 300 ccm of 5% sulphuric acid, warmed on a water bath for 6 hours, when resinous matter were obtained which solidified on cooling. It was recrystallized several times from alcohol, melted at 94° and proved to be identical with methysticol as described by Winzheimer. Analysis : - [table] The methysticol was also obtained from isomethysticin by the same manner as described in the case of methysticin. (April 1925 Tokio Hygienic Laboratory of Department of Home Affair).