Spectroscopic Studies of Brusatol

Abstract

The absolute stereochemistry of brusatol has been confirmed to be 55, 1R, 8R,9R, 105, 11R, 125, 135, 145, 15R by a combination of 2D nmr ['H-'H and 'H-^C (onebond and long-range) COSY], nOe, and cd spectroscopic analyses.In our studies on biologically active natural products, an antitumor quassinoid, brusatol [1], was recently isolated from the traditional Chinese medicine "Yandanzi," Brucea javanica (L.)Merr (Simaroubaceae) (1). Sim etal. (2) had previously reported that 1 was a bitter principle of Brucea sumatrana and that 2', 3' -dihydrobrusatol, which was obtained by the hydrogenation of 1, was identical with bruceine A [2], It is known that bruceines A [2], B [3], and C [4], bruceantarin [5], bruceantin [6], and bruceantiol [7] are the C20 quassinoids with the same basic skeleton as that of 1 and only differ in the nature of 15-ester grouping (3-7). The absolute stereochemistry of bruceine C [4} was elucidated on the basis of X-ray analysis of its tetraacetate by Polonsky et al. ( 7). Thus, the absolute stereochemistry of the basic skeleton of these quassinoids was assumed to be the same as that of 4. This paper is concerned with an approach to the absolute stereochemistry of 1 by a combination of high-resolution ('H, 400 MHz; 13C, 100.6 MHz) nmr and cd spectroscopic analyses. RESULTS AND DISCUSSIONNmr spectroscopy.-The nmr spectra were taken in pyridine-</5 unless otherwise cited. Because the resonances of H-15 and C-14 were obscured at ambient temperature and those of H-5, H-14, C-5, and C-15 were slightly broad, the spectra were measured at 50°. The ID nmr spectra showed the number of hydrogens (except three hydroxyls) and carbons corresponding to the molecular formula C26H32On of 1. The number of hydrogens attached to each individual carbon was determined by DEPT experiments: five methyls, three methylenes, eight methines, and ten quaternary carbons. Hydroxyls (exchangeable with D20) were examined in DMSO-</6. Several protons (H-lct and H-9, H-7 and HB-20, H-14 and HA-20) that displayed close or overlapping resonances in pyridine-</5 showed more separated resonances for each pair in DMSO-</6. The 1H-lH, one-bond 1H-1JC, and long-range 1H-13C COSY spectra are shown in

Characterization of brusatol self-microemulsifying drug delivery system and its therapeutic effect against dextran sodium sulfate-induced ulcerative colitis in mice

“…1 H NMR (400 MHz, DMSO-d 6 ) δ ppm: 2.63 (1H, s, H-1α), 3.28 (1H, d, J = 12.2 Hz, H-1β), 2.89 (1H, d, J = 12.8 Hz, H-5), 2.07 (1H, d, J = 2.0 Hz, H-6α), 1.71 (1H, m, H-6β), 4.92 (1H, s, H-7), 2.16 (1H, d, J = 3.2 Hz, H-9), 3.97 (1H, s, H-11), 4.10 (1H, s, H-12), 1.22 (3H, s, H-18), 1.72 (3H, s, H-19), 3.59 (1H, s, H-20a), 4.48 (1H, d, J = 7.2 Hz, H-20 b), 3.61 (3H, s, H-23), 5.62 (1H, s, H-2'), 2.10 (3H, s, H-4'), 1.90 (3H, s, H-5'), 7.86 (3H, s, 3-OH), 13 C NMR (100 MHz, DMSO-d 6 ) δ ppm: 49.2 (C-1), 193.2 (C-2), 144.7 (C-3), 128.8 (C-4), 41.5 (C-5), 29.1 (C-6), 83.0 (C-7), 41.0 (C-8), 40.6 (C-9), 45.2 (C-10), 71.9 (C-11), 75.0 (C-12), 81.7 (C-13), no assignable (C-14, C-15), 167.8 (C-16), 15.5 (C-18), 13.7 (C-19), 72.7 (C-20), 170.4 (C-22), 52.5 (C-23), 164.5 (C-1'), 115.3 (C-2'), 158.8 (C-3'), 20.4 (C-4'), 27.4 (C-5'). Its spectroscopy data were consistent with the previous literature (Harigaya et al., 2004 ). Hence, the white powder obtained was identified as BR, and its structure was given in Figure 1(A) .…”

“…). Its spectroscopy data were consistent with the previous literature (Harigaya et al, 2004). Hence, the white powder obtained was identified as BR, and its structure was given in Figure 1(A).…”

Seven Quassinoids from Fructus Bruceae with Cytotoxic Effects on Pancreatic Adenocarcinoma Cell Lines

“…The structures of bruceine D (Lee et al , ), bruceine H (Sakaki et al , ), yadanziosides A, G (Sakaki et al , ), javanicoside C (Kim et al , ), bruceantinoside A (Okano et al , ) and brusatol (Harigaya et al , ) were elucidated by comparing their 1 H, 13 C NMR spectroscopic data with those published previously. The structures were then further confirmed by the means of APCI‐MS: bruceine D, C 20 H 26 O 9 , m/z 411 [M + H] + ; bruceine H, C 20 H 26 O 10 , m/z 427 [M + H] + ; yadanzioside A, C 32 H 44 O 16 , m/z 685 [M + H] + ; yadanzioside G, C 36 H 48 O 18 , m/z 769 [M + H] + ; javanicoside C, C 32 H 40 O 16 , m/z 681 [M + H] + ; bruceantinoside A, C 34 H 46 O 16 , m/z 711 [M + H] + ; and brusatol, C 26 H 32 O 11 , m/z 477 [M + H] + .…”

Isolation, chemotaxonomic significance and cytotoxic effects of quassinoids from Brucea javanica

“…The structures of other sixteen known compounds were identified by comparing their spectroscopic data (UV, MS, 1 H and 13 C NMR) with those of reported values and found to be bruceine D (3) [19], yadanzioside E (4) [20], brusatol (5) [21], bruceoside B (6) [22], bruceantinol (7) [23], yadanzioside K (8) [23], P (9) [24], bruceine A (10) [20], yadanzioside B (11) [20], bruceantarin (12) [25], bruceoside A (13) [26], yadanzioside C (14) [20], G (15) [20], F (16) [27], A (17) [20], and M (18) [23].…”