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The alkaloid composition of the roots ofCorydalis paniculigera Rgl., collected in the flowering phase in the Alai range, has been studied. Chloroform extraction yielded 0.39% of total alkaloids, from which were isolated wilsonirine, thalicmidine, coclaurine, stylopine, dihydrosanguinarine, sanguinarine, oxosanguinarine, adlumine, adlumidine, bicucculine, sibiricine, protopine, pancorine, and corunnine, and new alkaloids which have been called pancoridine (I) and pancorinine (II). The structures of (I) and (II) have been established on the basis of spectral characteristics and also the production of wilsonirine on their reduction in sulfuric acid.

The pKa values of a number of alkaloids in water or in aqueous ethanol have been measured by the potentiometric titration method: nuphleine — 4.59, 6.98; brevicolline — 5.17, 8.02; chelidonine — 6.40; sanguinarine — 7.32; chelerythrine — 7.53; stepharine — 8.48; d-pseudoephedrine — 9.49. For nuphleine and brevicolline, each of which has two nitrogen atoms capable of protonation, assignments have been made of pKa values to the corresponding atoms on the basis of the results of UV spectroscopy.

Methanolic extraction ofDicentra spectabilis L., collected in the flowering period in the botanical garden of Pyatigorsk Pharmaceutical Institute, has yielded 0.17% of combined alkaloids from the epigeal part and 0.25% from the roots. By the separation of these materials, dihydrosanguinarine, sanguinarine, scoulerine, cheilanthifoline, corydine, and protopine have been obtained.Dicentra peregrina Rudolph, collected in the flowering period on the island of Sakhalin, has yielded 1.8% of combined alkaloids from the epigeal part and 1.51% from the roots. From these combined materials have been isolated isocorydine, corydine, dicentrine, protopine, dihydrosanguinarine, sanguinarine, cheilanthifoline, bicuculline, lederine, scoulerine, isoboldine, predicentrine, reticuline, and allocryptopine.

It has been shown that the sulfates of the quaternary alkaloids sanguinarine and heleritrine react with alcohols to form the corresponding ethers of the pseudobases.

In the isolation and purification of the benzophanthridine alkaloids sanguinarine and chelerythrine two minor bases — 9,10-demethylenesanguinarine and 9,10-demethylene-9,10-dehydrosanguinarine — were isolated, and it was shown that the former is an artefact produced from sanguinarine in the process of isolation and also when the sulfates of the alkaloids are subjected to prolonged storage.

The spectra of sanguinarine and heleritrine acetates in various solvents have been studied. It has been shown that an equilibrium exists of the tautomeric forms of the acetates which depends on the polarity of the medium.

A comparative chemical study of five species of corydalis (Corydalis rosea Leych.,C. gigantea Trautv. et Mey,C. vaginans Royle,C. remota Fisch., andC. marschalliana Pers.) has shown that important characteristics of the individual species are not only the type but also the particular composition of the alkaloids within each group and, in particular, the presence of certain characteristic signs connected with the biosynthesis of the alkaloids such as 13-methyl derivatives, phenolic compounds, racemic forms, etc.