Millon reaction

Chondrofoline, CgjHgjOjNj, 2H2O, crystallises from methyl alcohol in triangular plates, m.p. about 135°, [ajffg — 280-6° (dry base N/10. HCl). It is a phenolic base, contains three methoxyl groups, does not give a Millon reaction, but in methyl alcoholic solution gives a faint, pink-purple colour with ferric chloride. The nitrate forms needles m.p. 225° (dec.). 

The latter is a microcrystalline powder, m.p. 265° (efferv.), [a] + 210° (N/10 HCl), gives a Millon reaction and like all the phenolic alkaloids of this group is readily oxidised by nitric acid. 

The quaternary fraction of pot curare, after the removal of some neoprotocuridine, was separated into a portion salted out by sodium bicarbonate, and a portion not so precipitated. The latter was fractionated on a plan described in the original, the most active product obtained being an amorphous iodide with a paralysing dose of 1- 5 mg. per kilo frog. This iodide was phenolic, gave the Millon reaction, but no strychnine-like reaction with bichromate and sulphuric acid. No crystalline product could be isolated, but on complete methylation certain of the fractions yielded crystalline methiodides as follows —... 

Some individual amino acids could be detected by specific color reactions such as the Millon reaction for tyrosine (1849), the Hopkins-... 

The second non-quaternary alkaloid of pot-curare, protocuridine, was crystallized from pyridine, and analysis showed that it was isomeric with neoprotocuridine. It differed from neoprotocuridine in that it gave the Millon reaction and was optically active. Complete methylation yielded... 

Tyramine, like other p-hydroxy compounds, gives a positive Millon reaction. 

Xanthoprotein reactions are given by proteins with aromatic side groups On addition of nitric acid, the product turns yellow and, after further addition of ammonia, orange. The Millon reaction is specific for tyrosine On boiling, e.g., egg-white solution with a solution of mercury in nitric-acid containing nitrous acid, a red-brown precipitate is formed. 

Protocuridine contains two phenolic hydroxyl and two methoxyl groups and gives a typical Millon reaction. On methylation it yields 0-dimethylprotocuridine dimethiodide, CjgHggOgNj, (OMe)g(MeI)2, cream-coloured needles, m.p. 818° (dec.), which King (1940) has compared with the dimethiodide of isochondroidendrine dimethyl ether (p. 866), m.p. 812°, and finds that they are probably identical. On this basis he suggests for protocuridine a formula (see p. 379) of the fsochondrodendrine type. One phenolic hydroxyl must be at ORg the site of the second is still unknown. 

Excess tyrosine in the serum and urine can be detected by chromatography. It can be measured fluorimetrically in serum by its reaction with a-nitroso-jS-naphthol and nitrite in the presence of nitric acid. Tyrosine can be detected in urine by the Millon reaction when it gives a red colour with mercuric nitrate in nitric acid containing a trace of nitrous acid. 

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