A new bisbenzylisoquinoline alkaloid, (+)-limacusine-2'-P-N-oxide 111, was isolated from the leaves of Anisocycla joflyana, along with nine known alkaloids: (-)-2' norlimacine, (-)-2-norlimacine, (-)-limacine, (-)-limacine-2'-P-N-oxide, (+)-homoaromaline, (+)-milobine, (+)-isotrilobine, (+)-dehydro-1,2-telobine, and (+)-remrefidine. The structure of 1 was established by spectral methods.As part of our ongoing investigation of alkaloids from Anisocycla species (Menispermaceae), we reported recently the isolation and the identification of bisbenzylisoquinoline, protoberberine, aporphine alkaloids, and quinones from A. cymosa Troupin (1-4). Among these compounds, cocsoline and its derivatives showed antiprotozoal activity against Plasmodium falciparum, Giardia lamblia, and Entamoeba histolitica (2). The results of a phytochemical investigation of the leaves of A. jollyana (Pierre) Diels, another potential source of bisbenzylisoquinoline alkaloids, are described herein. This plant is the second Anisocycla species found growing in southwestern Zaire; it has no known uses in traditional medicine.Combined cc and prep. tlc on Si gel and on Al₂O₃ of a MeOH extract of A. jollyana leaves resulted in the isolation of ten alkaloids.Compound 1 was obtained as colorless needles from CHCl₃/MeOH. Its uv spectrum displayed maxima at 230 and 282 nm, indicative of being a bisbenzylisoquinoline alkaloid (5). This observation was further supported by eims and ¹H-nmr spectrometry. The eims of 1 showed a molecular ion of medium intensity at m/z 624 consistent with the elemental composition, C₃₇H₄₀N₂O₇, accompanied by five prominent peaks at m/z 608, 381, 367, 191⁺⁺, and 174. The m/z 608 [M-16]⁺ (78) ion, which was attributed to the loss of an oxygen atom from the molecular ion, is diagnostic for an N-oxide (6-8). The m/z 381 fragment represented the upper half of the molecule (7-10), while a m/z 191⁺⁺ ion corresponded to the doubly charged upper half of the m/z 608 species. As expected for a bisbenzylisoquinoline incorporating 7-8' and 11-12' ether linkages (oxyacanthine-type alkaloids), the eims also showed an ion at m/z 501 [M-16-107]⁺, characteristic for D-ring loss (9). The ¹H-nmr data of 1 are similar to those reported for (+)-limacusine (11-13) with regard to the aromatic protons and the substituents. A remarkable difference, however, was found in the signals corresponding to the 2'-N-methylgroup and the asymmetric proton H-1', which were both shifted downfield. The 2'-N-methyl singlet at δ 3.19 and the H-1' proton signal at δ 4.63 are characteristic of a trans-relationship between the Noxide oxygen and H-1' (8,10,14). The presence of an nOe effect between H-1' (δ 4.63) and the 2'-N-methyl singlet (δ 3.19) confirmed this configuration (15) as expected for a bisbenzylisoquinoline incorporating 7-8' and 11-12' ether linkages. Finally, 1 was reduced with zinc in HCl to afford the known alkaloid (+)-limacusine (11,12). These results established 1 as limacusine-2'-P-N-oxide. This new dimer, belonging to the oxyacanthine subgroup, exhibited a moderate positive specific rotation, [α]²⁵D + 157° (c= 1.1, CHCl₃), and, therefore, the same RR' absolute configuration as (+)-limacusine.The other alkaloids were identified by direct comparison of their tlc behavior as well as their uv, ¹H-nmr, and eims data with those of alkaloids isolated previously (14, 16). Three dimers, trilobine (0.036%), isotrilobine (0.044%), and dehydro-1,2-telobine (0.090%) belong to the trilobine subgroup; one dimer, (+)-homoaromaline (0.720%) to the oxyacanthine subgroup; four dimers, (-)-2'-norlimacine (0.010%), (-)-2 norlimacine (0.292%), (-)-limacine (0.382%), and (-)-limacine-2'-P-N-oxide (0.012%) to the berbamine subgroup; and one, remrefidine (0.172%) to the aporphine subgroup of benzylisoquinoline alkaloids.