Alantolactone 204

The commercial helenin,5) also known as alant camphor, is chemically alantolactone and is the principal constituent of the oil of elecampane root (from Inula Helenium).

Kallen6) originally regarded it as alantic acid anhydride, whereas Bredt and Posth7) recognized its lactone character and changed the name accordingly to alantolactone.

Recrystallized from dilute alcohol, alantolactone is obtained in colorless, prismatic needles which melt at 76°8) and which possess a slight odor and taste. It sublimes when only moderately heated and boils at 275° with partial decomposition. Under 10 mm. pressure it boils at 192V) Even in hot water it is but sparingly soluble, but readily in alcohol, ether, chloroform, glacial acetic acid, benzene and petroleum ether. Cold sodium carbonate solution does not dissolve it. When gently heated with dilute alkalies it dissolves forming solutions of the salts of the corresponding hydroxy acid, the alantic acid, C14H20OH-COOH. From these solutions the lactone is precipitated upon the addition of mineral acids. Characteristic derivatives of alantolactone are its monochlorhydrate, m. p. 117°, the monobromhydrate, m. p. 106°, the dichlorhydrate, m. p. 127 to 134°, and the dibromhydrate, m. p. 117°.

1) Semmler, Berl. Berichte 39 (1906), 2856.

2) Perkin, Liebig's Annalen 157 (1871), 116.

3) Ciamician and Silber, Berl. Berichte 35 (1902), 4130; 36 (1903), 4266.

4) Pharmaceutical Journ. 75 (1905), 476.

5) The name helenin is applied to no less than three different substances. Gerhardt [Annal. de Chim. et Phys. II. 72 (1839), 163 and III. 12 (1844), 188; Liebig's Annalen 34 (1840), 192 and 52 (1844), 389] applied the name to his impure alantolactone. Kallen [Berl. Berichte 6 (1873), 1506; compare also Kallen, Uber Alantolacton und die Anlagerung von Blausaure an ungesattigte Lactone, Inaug.-Dissert. Rostock 1895] applied it to an impure alantolactone contaminated with traces of oil of elecampane. Finally, the name is also applied to the inulin of the elecampane root. The helenin of commerce is well nigh pure alantolactone.

6) Berl. Berichte 9 (1876), 154.

7) Liebig's Annalen 285 (1895), 349.

8) Most of the commercial products reveal a somewhat lower melting point.

Alantolactone is accompanied by a small amount of a sub-stance which Kallen designated helenin and which was later isolated by Sprinz2) and studied more carefully by him. Because of the same elementary composition with alantolactone, C15H20O.2, and because of its chemical behavoir, Sprinz has named this compound Isoalantolactone. When pure it forms white prisms which melt at 115°, and which dissolve in benzene, ether, chloroform and absolute alcohol. In contrast to the behavior of alanto-lactone, it crystallizes unchanged from hot soda solution. It is only after boiling for about 5 to 6 hours that it is changed to the sodium salt of Isoalantolic acid which is precipitated from the solution when acidulated with hydrochloric acid. When melted this loses water and is reconverted to Isoalantolactone.

Medicinally, alantolactone is used as internal antiseptic. Added to urine it prevents putrifaction even in dilutions of 1:10000.

1) Bredt and Posth, Liebig's Annalen 285 (1895), 349. 2) Arch, der Pharm. 239 (1901), 201.