Rearranged limonoids from Harrisonia brownii

Rearranged limonoids from Harrisonia brownii

Pergamoa Phykxhmistry, Vol. 35. No. 2. PP. 451-454. 1594 Copyrisht Q 1994 Eismn Sncnce Ltd Pnnted in Great Britain. All rights rcxrxd 0031-9422194 %...

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Pergamoa

Phykxhmistry, Vol. 35. No. 2. PP. 451-454. 1594 Copyrisht Q 1994 Eismn Sncnce Ltd Pnnted in Great Britain. All rights rcxrxd 0031-9422194 %.CO+O.oO

REARRANGED

LIMONOIDS

FROM

HARRISONIA

BRO WNII

KATSUYOSHIMITSUNAGA,KAZUO KOIKE, KIYOSHI ISHII and TAICHI OHMOTO+ Department of Phannacognosy, School of Pharmaceutical Sciences,Toho University, 2-2-1, Miyama, Funabashi, Chiba 274, Japan (Received 15 lune 1993)

Key Word Index-Harrisonia brownii; Simaroubaceae; crystal structure analysis; limonoids.

bark; wood; brownin C; brownin G; X-ray

Abstract-A new limonoid, brownin C, was isolated from the bark of Harrisonia brownii, and a new limonoid, brownin G, from the wood of the same plant. Their structures were determined by spectral techniques and X-ray crystal structure analysis.

INTRODUCIION

A computer-generated perspective drawing of the final X-ray model of brownin C (1) is given in Fig. 1. From the above, the structure of brownin C was concluded to be as shown in formula 1. Brownin G (2) was obtained as prisms. Its molecular formula was determined as CZ9H340, l by mass measurement (FAB-MS m/z 581 [M+Na]+ and 559 [M+H]+) and from the i3C NMR spectrum. Its IR and UV spectra showed absorption bands due to a lactone group (v,, 1787 cm-i) and a /3-substituted furan ring (&,,,, 236 nm). The ‘HNMR spectrum of 2 showed signals due to four tertiary methyls at 6 1.28 (Me-lo), 1.30 (Me+, 1.38 (Me-4) RESULTS AND DI!SCUSION and 1.72 (Me-8), a secondary methyl at 6 1.16 (Me-13) and an acetoxyl at 62.03 (OAc-17). The results of Brownin C (1) was obtained as prisms. Its molecular ‘H-‘HCOSY indicated the presence of two isolated formula was determined as C2,HJ,,0i0 by high-resolustructural units, n-C(9)H-C(1 l)H,-C(12)H-C(13)Htion mass spectroscopy. Its IR and UV spectra showed absorption bands due to lactone (v,, 1785 cm-r) and (C(18)H3tC(17)H-¤ and n-C(2)H,-C(3)H-¤, in 2. The features of the *H and 13CNMR spectra of 2 were olefin (v, 1655 cm- ‘) groups and a /?-substituted furan ring (A,. 257 nm). ‘H-‘H 2DCOSY suggested the pre- virtually the same as those of brownin E (4) [2], except that the carbonyl function at C-17 in 4 was replaced by an sence of two isolated structural units, n-C(9)H-C(1 l)HC(12)H-H and n-C(2)H,-C(3)H-C(l’)H-C(Z’)H,-¤, in 1. acetoxyl group in 2. HMBC experiments with 2 clearly showed correlations from H-17 to the carbonyl carbon of The ‘H NMR spectrum (Table 1) of 1 was closely related to that of brownin B (3) [ 11, apart from the absence in 1 of OAc-17, thus indicating acetoxyl group to be located at the signals for the isopropenyl group. Instead of the C-17. The stereochemistry of brownin G (2) was estabsignals for the isopropenyl group seen in the spectrum of lished based on phase-sensitive NOESY experiments. From the multiplicity at H-12 (q, J = 10.6 Hz), the config3, compound 1 showed signals for a methine proton and gem-dimethyl groups. These findings are consistent with uration at C-13 may be R*. The coupling constant at Hthe “C NMR data (Table 2) which demonstrated a 17 (d, J = 6.0Hz), showed the configuration at C-17 to quaternary carbon at C-3 (696.6), C-4 (6140.5) and a also possibly be R* (Fig. 2). The structure of brownin G y-lactone carbonyl carbon at C-3’ (6 173.1) of 3; these was thus concluded to be that represented by formula 2. were changed to a methine carbon (643.9, C-3), quaternary carbon (679.7, C-4) and a 6-lactone carbonyl carbon EXPERIMENTAL (6168.6, C-3’) in 1, respectively. The above conclusion General. Mps: uncorr.; iHNMR (400 MHz) and was also supported by an X-ray crystal structure analysis which indicated the same relative stereochemistry as 3. *‘C NMR (100 MHz): DMSO-d6 and pyridine-d,, using TMS as the int. standard. Isolation of brownin C (1). Dried bark (3.0 kg) of *Author to whom correspondence should Lx addressed. Harrisonia brownii collected in Indonesia, in May 1990, previous papers reported the isolation and structural elucidation of four novel limonoids, brownins A, B, D and E, from the bark of Harrisonia brownii [l, 23. In the present study, two new limonoids were isolated and identified as brownins C (1) and G (2) from the bark and wood of the same plant, respectively. Their structures were determined by X-ray crystal structure analysis, the results of which are presented herein along with spectroscopic data and assignments.

451

452

K. MITSUNAGA et al.

0

0

2

Table 1*

H 2 3 9 11 12 13 17 18 19 21 22 23 28 29 30 1’ 2

2.82 2.07 2.75 2.92 5.92

4

1. ‘H NMR spectral

3.34ad(15.0) 2.68 p d (15.0) 2.95 d (9.0) 5.90 dd (11.4, 9.0)

6.18 d (11.7)

6.15d

1.61 s 1.34 s 8.53 s 6.67 br s 7.75 t (1.5) 1.30s 1.36 s

1.66s 1.19 s 8.46 br s 6.75 d (1.4) 7.72 t (1.4) 1.87 s 5.13a br d (1) 5.18b s 1.27 s 4.76 d (5.3) 2.97 add (18.7, 5.3) 2.32 /?d (18.7) 3.58 s

1.23 s 4.45 dd (9.0, 6.4) 2.87 a dd (19.5, 6.4) 2.12j?m

OMe

(11.4)

OCOMe Coupling constants *In DMSO-d6. tin pyridine-d,.

l-4

2t

30 ad (17.6) /Id (17.6) m d (9.2) dd (11.7, 9.2)

data for compounds

(J in Hz) are given in parentheses.

4t 2.46 (I dd (14.7, 10.3) 2.23 p m 3.49 m 263 br d (4.4) 2.23 a m 2.03/?ddd(14.3, 11.0.1.0) 3.25 q (11.0) 3.83 m

2.46 add (14.3, 10.1) 2.34 /I dd (14.3, 11.0) 3.83 m 2.54 br d (4.4) 2.03 a m 1.88 /3 ddd (14.3, 10.6, 1.0) 2.49 q (10.6) 2.57 m 5.84 d (6.0) 1.16d (7.0) 1.28 s 7.83 br s 6.60 d (1.8) 7.68 I (1.8) 1.38 s 1.30s

1.17 1.35 8.52 6.% 7.61 1.35 1.20

1.72 s

1.75 s

5.58 d (2.4)

5.87 d (2.6)

3.83 s 2.03 s

3.57 s

d (7.3) s br s d (1.4) t (1.4) s s

Rearranged limonoids from Harrisonia brownii

453

Table 2. 13CNMR spectral data for compounds l-4 1*

C 1

2 3 4 5 8 9 10 11 12 13 14 15 17 18 19 20 21 22 23 28 29 30 1’ 2 3’ OMe OCCMe OCO&

86.7 32.4 43.9 79.7 174.0 108.0 49.4 56.0 121.6 136.3 63.9 88.0 168.8 195.2 25.5 16.8 124.7 147.8 110.6 143.6 27.2 27.5 22.2 73.1 33.9 168.6 51.4

3*

2t

6

88.1 39.8 96.6 140.5 173.7 108.4 49.0 56.9 121.5 136.5 63.8 87.9 168.5 194.9 26.0 18.3 124.8 147.6 110.6 143.5 19.3 114.7 22.1 78.8 36.1 173.1 51.5

90.7 29.8 47.7 82.0 177.3 107.5 45.5 53.4 16.3 40.8 36.3 85.3 169.2 72.9 12.7 13.1 123.0 141.4 110.0 144.1 20.2 28.4 22.0 174.8 88.6 166.0 53.0 170.1 20.9

92.2 29.9 47.3 83.1 177.3 107.6 45.7 53.4 19.0 41.6 45.6 81.9 166.0 197.7 17.1 13.3 127.4 148.0 109.2 145.1 20.1 28.3 22.0 175.3 88.4

18

C28

170.1 52.7

*In DMSO-d,. tin pyridine-d,.

was extracted with CHCI, (45 1).The CHCI, extract was coned under red. pres. to give a residue (165 g) which was chromatographed on silica gel (2 kg) with CHCI, as the eluent containing increasing amounts of MeOH (1,5,10, 20, 50 and 100%). The frs obtained by elution with CHCl,-MeOH (19:l and 9:l) afforded a mixture of limonoids (58 g), which were repeatedly chromatographed on siiica gel and then recrystallized from MeOH to give brownin C (1) (71.5 mg). Erownin C (1). Prisms (MeOH), mp 293-295”. [a]F - 194.2” (pyridine; c 1.0); UV E” nm (logs): 257 (3.71); IR c;cm-I: 1785, 1750, 1672, 1655, 1560, 1505, 1280, 1225, 1180, 1160, 1065, 1040 and 910; HR-MS m/r: 515.1907 [M+H]+ (calcd for C,,H,,O,& 515.1908); EIMS m/z(rel. int.): 513 [M-H]’ (1),481(5X453 (lo), 358 (12), 326 (61), 315 (35), 283 (30), 253 (7), 221 (17), 95 (100) and 43 (68); ‘H NMR: Table 1; 13C NMR: Table 2. X-Ray crystal structure analysis of compound 1. Crystals from M&H-H,0 belonged to the triclinic space group Pl with a=7.3606(6), b-8.945(2) and c=9.897(2) A, V=622 A3, Z= 1, C,,HS,O,,, M, 514.54 DC= 1.37gcz1-~, j~(CuK~=7.86cm-‘. Crystal dimensions were 0.45 x0.25 x0.20 mm, and the number of reflections measured was 2330 (total) or 2564 (unique). The X-ray structure wasdetermined by direct methods

% Fig. 1. Perspective drawing of brownin C (t).

NOE

NOE Fig. 2

(Mac Science MXCl8 diffractometer) with hydrogen atoms. Refinement was made by the full matrix least squares method; R = 0.026 (R, = 0.040). Archival crystallographic data have been deposited at the Cambridge Crystallographic Data Centre, University Chemical Laboratory, Lensfield Road, Cambridge CB2 1EW. U.K. Please specify the complete literature citation when ordering. friction of browse G (2). Dried wood (10 kg) of the same plant was extracted with CHCI, (80 1).The CHCIJ extract was coned under red. pres. to give a residue (58 g) which was chromatographed on silica gel (900g) with CHCI, as the eluent containing increasing amounts of

454

K. MITSUNAGAet

MeOH (1, 5, 10, 20, 50 and 100%). The frs obtained by elution with CHCI,-MeOH (19: 1) afforded a mixture of limonoids (23 g), which were subjected to CC on Diaion HP-20 and then recrystallized from MeOH to give brownin G (2) (8.2 mg). Brownin G (2). Prisms (MeOH), mp 240-241”. [a];’ + 77.0” (pyridine; c 1.O);UV a:$“” nm (log E): 236 (3.99); IR yK,t):cm-‘: 1787, 1736, 1693, 1675, 1505, 1273, 1237, 1185, 1162, 1105, 1022,981 and 907. FAB-MS m/z: 581 [M+Na]+, 559 [M+H]+; HRMS m/z: 516.1989 [M -C,H,O]+ (calcd for C27H3,0,0: 516.1986); EIMS m/z (rel. int.): 516 [M-C,H,O’J’ (26), 489 (19), 483 (4), 454 (8). 420 (18), 402 (3), 375 (4), 333 (lo), 319 (14), 292 (5). 245 (6),221 (19),203(8),134(27), 105(10),97(15),81 (9),55(7) and 43 (100); ‘H NMR: Table 1; ‘-‘CNMR: Table 2; Phase-sensitive NOESY: H-2a+H-28, H-2B-+H-3, H3-+H-29, H-9+H-1 l/I, H-9+H-19, H-9-H-30, H1la+H-13, H-l la+H-19, H-ll@+H-30, H-12+H-17,

al.

H-13+OAc-17, H-l’?-+H-18. H-17+H-21, H-29+OMe-15.

H-17+H-22,

Acknowledgements-The authors thank Eisai Co., Ltd and P. T. Eisai Indonesia Co., Ltd for kindly supplying the plant materials, Dr M. Takayama (the Analytical Laboratory of this school) for measuring MS, and Dr H. Inoue (Mac Science Corporation) for the X-ray analysis and his helpful comments. REFERENCES

1. Koike, K., Mitsunaga, K., Ishii, IC., Ohmoto, T., Kawakami, Y., Ikemori, M. and Sato, T. (1993) Tetrahedron 49, 2209. 2. Mitsunaga, K., Koike,

K., Ishii, K., Ohmoto, T., Uchida, A., Oonishi, I. and Ohashi, Y. (1993) Tetrahedron Letters (in press).