The alkaloids protopine, d- and dl-bicuculines, d-~-hydrastine, l-adlumidine, scoulerine, coreximine, sanguinarine, wilsonirine, and corphthaline have been isolated from Corydalis pseudoadunca M. Pop. [1-6]. Continuing a study of the epigeal part of this plant collected in Kaltabulaksae in the flowering phase, we have obtained by chloroform extraction 1.39% of combined alkaloids and have separated them into phenolic and nonphenolic fractions. By separating the combined material according to solubility in organic solvents and also by chromatography in a column of silica gel, in addition to the alkaloids mentioned above with the exception of dl-bicuculine, we have isolated juziphine [7], coclaurine [8], reticuline [9], stylopine [10], sibiricine [11], and base (I). All the compounds were identified based on special characteristics and comparison with authentic samples. Base (I) was amorphous, [α]D +27° (c 0.3; methanol). Its mass spectrum showed a weak molecular ion peak at m/z 345 and ions at m/z 329, 328, 327, 192 (100%), and 137. The PMR spectrum (deuteropyridine) had three-proton singlets at 3.03 ppm (N-methyl), 3.59 and 3.64 ppm (two methoxy groups), five aromatic protons at 6.50-7.70 ppm, and methylene/methine protons at 2.59-4.90 ppm. Spectral characteristics, poor solubility in organic solvents, and a 16-mass-unit difference from reticuline suggested it was reticuline N-oxide. Reduction with zinc in sulfuric acid gave a product identical to reticuline (IR, TLC). Reticuline N-oxide was previously obtained from Pochykone ovata (Menispermaceae) [12] but without specific rotation. This is the first detection of (+)-reticuline N-oxide in Papaveraceae plants.