Five new acrimarines (acridonecoumarin dimers) were isolated from some Citrus plants (Rutaceae) and their structures were elucidated by spectroscopic method. Recently, we reported the isolation and structure el~cidation of acrimarine-A--H, dimeric compounds in which an acridone unit has been coupled to a coumarin. Further examination of the roots of "Yalaha" [several hybrid seedlings resulting from a cross of Duncan grapefruit (Citrus paradisi Macf.) x Dancy tangerine (L Lanlerine Hort. ex Tanaka)] and "Funadoko" (L funadoko Hort. ex Tanaka) afforded five new compounds, named acrimarine-l (I), -J (4), K (5), -L (6) and -M (7) and in this paper we wish to report the isolation and structure elucidation of these new compounds. Acrimarine-1 (1) was obtained as yellow oil, [α]D +27.8°(~~~13). The high resolution ms showed molecular formula C34H31NO7, which was considered to give rise to two characteristic ions from the halves of the molecule at m/z 323 and 242 corresponding to formulae C19H17NO4 and C15H14O3 respectively, indicating the presence of acridone and coumarin structures. The ir (3400, 1720, 1620, 1560 cm⁻¹) and uv [205, 223 (sh), 270 (sh), 296, 328, 348 (sh) nm] spectra suggested the presence of 1-hydroxy-9-acridone moiety. The ¹H nmr spectrum showed the presence of hydrogen bonded hydroxyl group (δ 14.63), ABC type aromatic protons [δ 7.94 (1H, dd, J=7.9, 1.8 Hz), 7.15 (1H, t, J=7.9 Hz), 7.09 (1H, dd, J=7.9, 1.8 Hz)], 1.1-dimethylpyran ring [δ 6.61 (1H, d, J=9.8 Hz), 5.48 (1H, d, J=9.8 Hz), 1.14, 1.46 (each 3H, s)], characteristic H-4', H-3', H-5' and H-8' of coumarin nucleus [δ 7.67, 6.22 (each 1H, d, J=9.2 Hz), 7.62, 6.69 (each 1H, s)], and a prenyl group connected with two aryl moieties [δ 5.94 (1H, d, J=9.8 Hz), 5.74 (1H, d, J=9.8 Hz), 1.80 (3H, s), 1.75 (3H, s)]. Two singlets at δ 3.75 and 3.72 in the ¹H nmr and two quartets at δ 55.9 and 48.5 in the ¹³C nmr spectra showed the presence of each one methoxy and α-methyl group. In nOe experiments, irradiation of the methoxy signal at δ 3.75 gave 20% increments of the signal at δ 6.69 (H-8'). On the other hand, when the α-methyl signal at δ 3.72 was irradiated, 13% increments were observed on the signal at δ 6.61 (H-11). From these results, the location of methoxy group was assigned to C-7' and the angular orientation of the dimethylpyran ring was confirmed. The similarities of signal patterns of ¹H nmr spectrum suggested the presence of 5-hydroxynoracronycine (z) and suherosin (3) moieties in the structure. The location of the suherosin unit was elucidated by ¹H detected heteronuclear multiple bond connectivity (HMBC) spectrum. The H-bonded proton signal at δ 14.63 showed long-range correlations with the carbon signals at δ 162.0 (C-1), 112.6 (C-2), and 107.1 (C-9a). Further, the proton signal at δ 5.74 (H-1'') was correlated with carbon signals at δ 162.0 (C-1), 112.6 (C-2), 159.0 (C-3), 132.9 (C-3''), 128.6 (C-5'), and 130.6 (C-6'). Other CH long range correlations observed are shown by arrows in Figure 1. Based on these spectral data, the structure of acrimarine-1 was concluded to 1. Acrimarine-J (4) was obtained as yellow oil, [α]D *0°(CHCl₃). The mass spectrum showed the molecular ion at m/z 595 which corresponded to C35H33NO8 a difference of CH2O compared with 1. The ¹H nmr features were similar to those of 1, except for appearances of one more methoxy (δ 3.90) signal and change of ABC type aromatic protons to AB type [δ 7.96, 6.97 (each 1H, d, J=8.5 Hz)]. The signals at δ 3.90, 3.84, 3.75 in the ¹H nmr and δ 60.5, 56.5, 48.9 in the ¹³C nmr spectra indicated the presence of two methoxy and one α-methyl group. The location of methoxy groups and the situation of 1.1-dimethylpyran ring were determined by nOe experiments. Irradiation of the signal at δ 3.75 and 3.84 showed 14% and 20% increments of the signals at δ 6.69 (H-11) and 6.83 (H-8'), respectively. When the signal at δ 3.90 was irradiated, no increments were observed on any signals. These results indicated the locations of methoxy groups at C-5 and C-7', phenolic hydroxyl group at C-6, and the angular situation of 1.1-dimethylpyran ring. On the basis of these results, structure (4) was assigned to acrimarine-J. Acrimarine-K (5) was isolated as yellow oil, [α]D *0° (CHCl₃). The molecular formula C30H27NO8 was established by high resolution ms. The ¹H nmr spectrum showed the signals of ortho coupled [δ 8.04, 6.94 (each 1H, d, J=8.8 Hz)], isolated [δ 6.48 (1H, s)] aromatic protons, characteristic signals due to H-4', H-3', H-5' and H-8' of coumarin nucleus [δ 7.88, 6.16 (each 1H, d, J=9.5 Hz), 7.73, 6.82 (each 1H, s)], and signals due to a prenyl group coupled to two aryl groups [δ 1.75 (3H, s), 1.72 (3H, s), 5.83 (1H, d, J=9.5 Hz) and 6.08 (1H, d, J=9.5 Hz)]. The signals at δ 3.98, 3.87, 3.77 in ¹H nmr and δ 40.2, 56.9, 62.2 in ¹³C nmr spectra indicated the presence of two methoxy and one 1-methyl group. The location of methoxy groups was determined by nOe experiments. Irradiation of the signal at δ 3.98 and 3.87 showed 14% and 16% increments of the signal at δ 6.48 (H-4) and 6.82 (H-8'), respectively. On the other hands, when the signal at δ 3.77 was irradiated, no increments were observed at any proton signals. Thus, the location of two methoxy groups was determined to C-5 and C-7'. From the above data, the location of suberosin unit was assigned at C-2 in the acridone skeleton, and the structure of acrimarine-K was determined to 5. The proposed structure was further confirmed by HC long range COSY shown by arrows in Figure 2. Acrimarine-L (6) was isolated as yellow oil, [α]D *0° (CHCl₃), and gave a molecular ion at m/z 529 which corresponded to C30H27NO8 the same as that of acrimarine-K (5). The ¹H nmr spectrum showed a good similarity with that of 5, except for small differences of chemical shifts indicating the presence of suberosin and 1.3.5.6-oxygenated 9-acridone units. The signals at δ 3.97, 3.94 and 3.87 indicated the presence of methoxy groups. In the nOe experiments, irradiation of the signal at δ 3.97 and 3.87 showed 17% and 14% increments of the signal at δ 6.34 (H-2) and 6.92 (H-8'), respectively. On the other hands, when the signal at δ 3.94 was irradiated, no increments were observed. Meanwhile, when the signal at δ 9.14 assumed to NH signal was irradiated, 12% and 9% increments were observed on the signal at δ 5.78 (H-1'') and 5.91 (H-2''), respectively. These results indicated the locations of methoxy groups were at C-3, C-5 and C-7', and the linking positions of acridone and coumarin rings were at C-4 and C-6', respectively. The above data led us to assign structure 6 to acrimarine-L. Acrimarine-M (7) was isolated as yellow oil, [α]D *0° (CHCl₃). The molecular formula, C29H25NO6, was confirmed by high resolution ms. The ¹H nmr spectrum showed, besides signals of suherosin unit, ABCD type [δ 8.38 (1H, d, J=8.1 Hz), 7.76 (1H, t, J=8.1 Hz), 7.73 (1H, d, J=8.1 Hz), 7.30 (1H, t, J=8.1 Hz)] and a lone [δ 6.54 (1H, s)] aromatic proton signal and two methyl singlets (δ 3.82 and 3.86). The location of two methyl signals at δ 3.86 and 3.82 was assigned by nOe experiments. When the signal at δ 3.82 was irradiated, each 14% and 10% increments were observed on the signals at δ 7.73 (H-5) and 6.54 (H-4), respectively. On the other hands, irradiation of the signal at δ 3.86 showed 11% increments of the signal at δ 6.82 (H-8'). The above data showed the presence of a-methyl group, the location of methoxy group at C-7', and the coupling position of the acridone and the coumarin nuclei was at C-2 and C-6'. From these results, the structure 7 was assigned to acrimarine-M. The absolute configurations of these new acrimarines remain to be determined.