South African Senecio alkaloids. Part 6. The toxic alkaloids of Senecio scleratus sp. nov. Schweikerdt

Abstract

(1) Senecio sceleratus sp. nov. 'Schweickerdt is an extremely toxic Senecio species. It contains at least three more or less toxic alkaloids, viz., isatidine, retrorsine and a new alkaloid, sceleratine, (2) Sceleratine, C₁₈H₂₇O₇N, crystallizes with one molecule of water of of crystallization from water and apparently three molecules of ethanol of crystallization from ethyl alcohol. M.P. 178°C, [α]D/21 = +54·0° (ethanol). (3) Upon catalytic hydrogenation sceleratine undergoes hydrogenolysis at the B-hydroxyl and retronecanol and sceleranecic dilactone acid are isolated. (4) Hydrolysis of sceleratine leads to the isolation of the well-known necine base, retronecine and a new dilactone necic acid viz. sceleranecic acid. (5) Sceleranecic acid has the formula C₁₀H₁₄O₅, the m.p. 156°C. (also 213°C.) and [α]24/D = -9.3 (water). (6) Sceleratine is bitter, fairly soluble in water and readily forms addition compounds with hydrochloric acid, nitric acid, picric acid, perchloric acid, methyl-iodide and aurichloride. (7) Experiments to determine the relative toxicity of the alkaloids mentioned are being carried out.