[2R,(-)]-3,9-Dihydro-8-methoxy-9-methyl-2-isopropylfuro[2,3-b]quinoline-4(2H)-one

Description

A further alkaloid obtained from the bark of Lunasia costulata Miq., this base belongs to the furoquinolone group of alkaloids. It crystallizes as the monohydrate in colourless needles from AcOET, m.p. 95.5°C, losing H20 at lOOoC to give the anhydrous form with the above melting point. The alkaloid has [α]²⁸_D - 58° (EtOH). The following salts have been prepared: the hydrochloride, m.p. l64-5°C; [α]²⁸_D - 23° (H20); hydro bromide, m.p. 170-1 DC; hydriodide, m.p. 196-7°C; aurichloride, m.p. l76-7°C; picrate, m.p. 2l3-4°C and the methiodide, m.p. l30-loC (dec.). The last of these, on treatment with moist silver oxide produces an isomer of lunacrine, m.p. 85-6°C, this behaviour resembling that of certain other Rutaceous alkaloids, e.g. Skimmianine (q.v.). The (+)-form oflunacrine has m.p. 119-1200 C; [α]²⁵₅₈₉ + 66° and [α]²⁵₄₃₆+ 100°. This form also yields a crystalline perchlorate, m.p. 178-1800 C. The optically inactive form has been prepared as colourless crystals from AcOEt-pentane, m.p. l46-8°C.The alkaloid inhibits peristaltic movement of the isolated intestine. The median lethal dose of the hydrochloride is approximately 78.7 mgm per kilo when injected intravenously in mice. It is also stated to reduce arterial blood pressure in cats.

Definition

ChEBI: Lunacrine is an organic heterotricyclic compound, an organonitrogen heterocyclic compound and an oxacycle.

References

Boorsma.,Meded. Lands. Plant., 31, 13, 126 (1899)
Boorsma.,Bull. Inst. Bot. Buit., No. 31, 8, 25 (1904)
Steldt, Chen., J. Amer. Pharm. Assoc., 32, 107 (1942)
Goodwin, Horning.,J. Amer. Chem. Soc., 81, 1908 (1959)
Clarke, Grundon., Chem. & Ind., 556 (1962)
Clarke, Grundon., J. Chem. Soc., 438 (1964)