12,18-ジヒドロキシセネシオナン-11,16-ジオン4-オキシド

説明This hepatotoxic alkaloid occurs in certain Senecio species and was first isolated from S. isatideus D.C. It occurs abundantly in S. retrorsus D.C. and S. scleratus Schw. The alkaloid crystallizes in rhombic prisms as the dihydrate and has [α]27D . 8.25° (H 20). It is soluble in MeOH, hot EtOH and hot H20 but virtually insoluble in Et 20, Me2CO or CHCl 3. On reduction it absorbs 4 molecules of H2 to give hexahydrodeoxyisatidine which melts at l15-l20°C and then remelts at l83-4°C following an intermediate solidification. This compound gives a hydrochloride, m.p. 218°C (dec.); [α]20D - 52.5° (H20) and may be hydrolyzed with Ba(OHh to give a basic product, tetrahydroisatinecine, CSH1703N, m.p. l74.5°C; [α]20D - 88° (H 20). The alkaloid itself, on hydrolysis with Ba(OHh yields isatinecine and two acid products, isatinecic acid and the monolactone, the latter almost certainly being formed by the action of the base upon the acid.