Haplophyllum buxbaumii has yielded three new lignan type A glucosides: majidine [2], qudsine [3], and arabelline [4], Cleistanthin B [1] is also reported for the first time from this family. Temperature-dependent nmr studies have provided insight into the conformational equilibria existing in 1, 2, and 4.In continuation of our systematic phytochemical investigation of Haplophyllum buxbaumii A. Juss. (Rutaceae) (1), we now report the isolation and structure elucidation of four diphyllin glucosides, three of which (2-4) are new. These are cleistanthin B [1], 4-The bluish fluorescence of the four lignan glucosides under uv light as well as their similar uv spectra (X max 261.6 nm) indicated that all these compounds bear an arylnaphthalene nucleus (2). The acid hydrolysis of the four lignan glucosides afforded the same aglycone, which was identified by spectral data as diphyllin [11] (12). The sugar residues, identified by tic comparison with authentic samples, were found to be glucose of compound 1, apiose and xylose of compound 2, apiose, arabinose, and glucose of compound 3, and arabinose and glucose of compound 4.The uv, ir, ms, and 'H-nmr spectra were reported for cleistanthin B (3). As the 'Hnmr assignments were not fully made, we present in Table 1 the 'H-nmr spectrum with the assignments of the individual aromatic protons. The 13C-nmr chemical shifts and multiplicity assignments of cleistanthin B are shown in Table 2.Compound 2 was assigned the molecular formula C31H32015) positive fabms m!z 645 [M + H]+). The 'H-nmr spectrum of the acetylated derivative 6 of compound 2showed five 3 H singlets in the region between 2.02 and 2.14, corresponding to the aliphatic acetoxy groups, indicating the presence of five aliphatic hydroxyl groups. The 13C-nmr spectrum (DMSO-6, 75.43 MHz) of 2 showed the presence of 31 carbons.The sequence of the sugar units in compound 2 was determined by spectral analysis. The positive ion fabms exhibited ions at mtz 645, 513, and 381, which were assigned to [ + H]+, [ + Hpentose]"1", and [ + H -2 pentose]+, respectively.The 13C-nmr spectrum of compound 2 showed that there were 10 carbon resonances corresponding to the sugar moiety. Of these, two were the anomeric carbons resonating at 109.8 and 105.0, while the rest resonated in the region 62.5 to 84.5. DEPT experiments (5) showed one quaternary carbon at 79.7 and three methylene carbons at