(+)-Lamprolobine (2), the novel alkaloid (+)-9β-hydroxylamprolobine (3), and cytisine were isolated as the major alkaloids from the leaves of Sophora velutina var. zimbabweensis. The alkaloids were characterized on the basis of ir, ms, [α]D, ¹H and ¹³C nmr, and by two-dimensional nmr spectral assignments. Although more than twenty species of Sophora (tribe Sophoreae: Leguminosae) have been investigated for their alkaloidal constituents, there is no previous report concerning Sophora velutina Lindl. Matrine- and anagyrine-type alkaloids are typical of the genus, and although other alkaloids such as sparteine- and dipiperidine-types do occur, their distribution is more limited. Recently, the lipinane-type alkaloids (-)-epilamprolobine (1) and its N-oxide have been reported as very minor alkaloids of Sophora tomentosa (1). In this paper, lamprolobine-type alkaloids are reported as being major constituents of S. velutina Lindl. var. zimbabweensis Gillett and Brummitt. Three major alkaloids, (+)-lamprolobine (2), (+)-9β-hydroxylamprolobine (3), and the well-known cytisine were isolated from the leaves of S. velutina. The known alkaloid (+)-lamprolobine (2) was identified on the basis of its spectral properties ([α]D, ir, ¹H and ¹³C nmr, ms), which were compared with those of (-)-epilamprolobine (1) (1,2). The complete assignment of the nmr spectra was achieved by means of mono- and two-dimensional techniques, and, in particular, the following differences were noted between the spectra of (1) and (2): (a) The carbon signals observed for 2 were almost identical to those reported for 1, with the exception of those signals attributed to 3-C, 5-C, and 11-C (Table 1). (b) The chemical shifts of the 11-C protons of 1 have been reported as being well separated, occurring at δ 3.77 and 4.28 (1), whereas in the ¹H nmr of 2, these signals nearly coalesced at δ 3.7 (Table 2). The ir spectrum of the other major alkaloid (3) indicated the presence of a trans fused quinolizidine ring system (strong Bohlmann bands at 2800-2700 cm⁻¹) and an imide function [1670 (s), 1720 (w) cm⁻¹]. In addition, strong absorption bands at 3600 and 3300 cm⁻¹ indicated the presence of a hydroxyl group. The molecular formula of C₁₅H₂₄N₂O₃ was obtained from ms measurements (M⁺, m/z 280.1787; calcd 280.1783), and the fragmentation indicated a lamprolobine-type structure (3) with one additional hydroxyl group present in ring A (C₅H₉NO, m/z 99.0686; calcd 99.0686). The presence of the hydroxyl substituent was confirmed by preparation of an O-acetyl derivative, and the position of substitution at 9-C was determined by ¹H nmr (Table 2). The ¹H-nmr spectrum of (3) (Figure 1) displayed a series of signals integrating for three protons in the 3.7 ppm range; two of these signals were attributed to the 11-C protons (see above), whereas the remaining signal was assigned to the proton at the carbon substituted by the hydroxyl group. The chemical shift of the signals attributed to the methylene protons of 11-C coincided with those of the corresponding signal obtained for (+)-lamprolobine (2), indicating that both alkaloids possessed the same relative configuration at 5-C. Because the chemical shifts were known for the two methylene protons at 11-C, it was possible to analyze the correlation pattern as revealed by the cross peaks laying off the diagonal in the 2-D proton-proton contour map (Figure 1), thus leading to the complete assignment of the ¹H-nmr spectrum of (3) (Table 2). From these assignments, it is obvious that 9-C is the position of hydroxyl substitution. The spin-spin analysis of the 9-CHOH-10-CH₂N fragment provided the information needed for the assignment of the hydroxyl configuration. The coupling constants ³J₉-₁₀ₑ=4.3 Hz and the ³J₉-₁₀ₐ=11 Hz correlating with dihedral angles of 49° and 180° respectively, consistent with an equatorial hydroxyl substituent at 9-C. The [α]D of the new alkaloid was determined as +24°, and hence, it is identified as (+)-9β-hydroxylamprolobine (3). Additional support for our conclusions came from the assignment of the ¹³C spectrum of (3). Thus, where the carbon shifts of (3) were compared with those of (1) and (2) the following facts were noted: (a) C-9 undergoes a large chemical shift variation in (3) (40 ppm) consistent with hydroxyl substitution; (b) the chemical shift of C-5 and C-11 is virtually identical in (2) and (3), indicating that there is identical configuration at C-5 for both compounds. Lamprolobine-type alkaloids have been reported previously from Lamprolobium (tribe Bossiaeeae) (2) and from Lupinus (tribe Genistae) (4). This is the first report of these alkaloids as major constituents of Sophora, and the results show that there is a strong chemical relationship between the tribes Sophoreae, Bossiaeeae, and Genistae, supporting their botanical affinities (5).