The alkaloids of Buxus sempervirens L. cultivated in the Karachaevo-Cherkeskii autonomous province of Stavropol' krai, which had not been previously studied, were investigated. Total alkaloid contents of various plant organs (first-year shoots, young roots, leaves and twigs, flowers, roots, perennial twigs, fruit, perennial flowers) at two collection dates (May 7 and July 25, 1980) were determined using the chloroform method, with values ranging from 0.96% to 2.46%. The combined alkaloids isolated from May-collected twigs and leaves were separated by citrate-phosphate buffer solutions (pH 8.0-2.0) and column chromatography (alumina, silica gel), yielding cyclobuxine-D, cyclovirobuxine-D, cycloprotobuxine-A, cyclobuxine-B, and a new alkaloid (mp 245-247°C, M⁺ 440) belonging to the 9β,19-cyclo-5α-pregnane type. Additionally, cyanogen bromide hydrolysis of rat transferrin (a group of homologous glycoproteins capable of reversibly binding ferric iron ions in two molecular centers, assumed to have evolved from a single-center ancestral protein) was performed. Based on methionine residue analysis, five fragments were theoretically expected and confirmed by polyacrylamide gel electrophoresis. These fragments were separated on a Sephadex G-50 column into five fractions (BF-1 to BF-5), and their homogeneity was checked by SDS-polyacrylamide gel electrophoresis, which showed substantial aggregation in fraction BF-I.