キノトキシン塩酸塩

説明Although this alkaloid from the bark of Cinchona species was first isolated by Howard in 1871, it had earlier been prepared by Pasteur by heating the acid sulphate of quinine and Hesse subsequently prepared it in a similar manner from quinidine. The identity of the alkaloid with quinotoxine, formed by heating quinine in H20 or dilute AcOH was proved by von Miller and his co-workers. The base forms a bitter, yellow varnish having [α]D + 38.6° (CHCI 3 ) and is normally purified through the oxalate nonahydrate which has m.p. 166-7°C;[α]20D + 24°. The alkaloid yields crystalline salts, the hydrochloride forming colourless leaflets, m.p. l80-2°C; [α]]13.7D + 16 26° (H20); the oxime, m.p. l12-6°C; dipicrolonate, m.p. 210°C; the (+)-tropate monohydrate, m.p. l12-3°C or l16-8°C (dry). The p-bromophenylhydrazone forms yellow crystals, m.p. 141°C. Both the N-methyl and N-ethyl derivatives are yellow oils, the former yielding a hydrochloride monohydrate, m.p. l53-5°C; [α]23D + 16.6° (H20) and the latter the corresponding hydrochloride, m.p. 202-4°C; [α]23D + 68.1 ° (H20). The N-benzoyl derivative crystallizes from C6H6 or MeOH with m.p. l13-4°C; [α]22D + 36° (c 2.0, EtOH). According to de Caro, the minimum lethal dose for white rats is 0.32 gm/kilo compared with 1.25 gm/kilo for quinine and, although it has no anti-malarial action, the alkaloid appears to be less toxic than formerly supposed.