Continuing a study of the alkaloid composition of Diptychocarpus strictus seeds collected in Chimkent oblast (September 1976), 0.13% total alkaloids were obtained via chloroform extraction. A new crystalline base (I) (C₇H₁₈N₂OS, mp 118-119°C) was isolated from the pH 2.2 fraction by polybuffer distribution. Spectral (IR, NMR, MS) analysis and oxidation with hydrogen peroxide (yielding diptocarpaine) identified base (I) as 6-thiomethyl-N-n-hexylurea, a deoxy product of diptocarpaine. From the epigeal part of D. strictus collected in Dzhizak oblast (April 1976), 0.1% combined alkaloids were obtained, and a base (III) (C₄H₁₀N₂O, mp 157-158°C) was isolated via alumina column chromatography; it was identified as isopropylurea, the first isolation from a plant. Additionally, continuing separation of Corydalis severzowi total alkaloids, a new base severzinine (I) (mp 90-91°C, [α]D +109°) was isolated from the nonphenolic part. Spectral analysis and comparison with dihydrosibiricine (from sibiricine reduction) confirmed severzinine as a spirobenzylisoquinoline alkaloid identical to dihydrosibiricine.