Glycosides and Saponins from Cestrum leaves
J ournal of Natural Products, 2001, Vol. 64, No. 1 21
(C-2′′), 78.2 (C-3′′), 71.3 (C-4′′), 77.2 (C-5′′), 67.6 (C-6′′), 106.2
(C-1′′′), 76.1 (C-2′′′), 78.2 (C-3′′′), 71.4 (C-4′′′), 75.8 (C-5′′′), 64.5
(C-6′′′), 102.2 (C-1′′′′), 72.1 (C-2′′′′), 72.5 (C-3′′′′), 73.9 (C-4′′′′),
69.5 (C-5′′′′), 18.4 (C-6′′′′), 125.0 (C-1′′′′′), 106.5 (C-2′′′′′ and
C-6′′′′′), 149.0 (C-3′′′′′ and C-5′′′′′), 140.4 (C-4′′′′′), 145.9 (C-7′′′′′),
115.2 (C-8′′′′′), 167.5 (C-9′′′′′), 56.3 (OMe); FABMS (positive
mode) m/z 999 [M + Na]+, 977 [M + H]+; FABMS (negative
mode) m/z 975 [M - H]-, 829 [M - H - rhamnosyl]-, 769 [M
- H - (acyl group)]-, 607 [M - H - glucosyl - (acyl group)]-;
anal. C 52.37%, H 5.85%, calcd for C45H52O24‚3H2O, C 52.43%,
H 5.67%.
3.97 (1H, dd, J ) 8.7, 8.7 Hz, H-4′′), 4.02 (1H, br dd, J ) 8.7,
6.1 Hz, H-5′′), 4.38 (1H, br d, J ) 11.2 Hz, H-6′′a), 3.88 (1H,
dd, J ) 11.2, 6.1 Hz, H-6′′b), 5.66 (1H, d, J ) 6.2 Hz, H-1′′′),
4.22 (1H, H-2′′′), 4.21 (1H, H-3′′′), 4.20 (1H, H-4′′′), 4.49 (1H,
dd, J ) 11.4, 3.9 Hz, H-5′′′a), 3.78 (1H, dd, J ) 11.4, 8.6 Hz,
H-5′′′b), 5.21 (1H, br s, H-1′′′′), 4.30 (1H, H-2′′′′), 4.31 (1H,
H-3′′′′), 4.09 (1H, H-4′′′′), 4.08 (1H, H-5′′′′), 1.45 (3H, d, J )
5.5 Hz, Me-6′′′′); 13C NMR (C5D5N) δ 157.7 (C-2), 134.7 (C-3),
178.8 (C-4), 162.5 (C-5), 98.4 (C-6), 165.7 (C-7), 92.4 (C-8), 106.3
(C-5a), 157.3 (C-8a), 55.8 (OMe), 122.1 (C-1′), 132.1 (C-2′),
116.3 (C-3′), 161.7 (C-4′), 116.3 (C-5′), 132.1 (C-6′), 100.3 (C-
1′′), 82.4 (C-2′′), 78.6 (C-3′′), 71.3 (C-4′′), 77.3 (C-5′′), 67.9 (C-
6′′), 105.9 (C-1′′′), 75.1 (C-2′′′), 77.3 (C-3′′′), 71.3 (C-4′′′), 66.8
(C-5′′′), 102.3 (C-1′′′′), 72.1 (C-2′′′′), 72.5 (C-3′′′′), 73.9 (C-4′′′′),
69.6 (C-5′′′′), 18.4 (C-6′′′′); FABMS (positive mode) m/z 763 [M
+ Na]+; FABMS (negative mode) m/z 739 [M - H]-, 607 [M -
H - xylosyl]-, 583 [M - H - rhamnosyl]-; anal. C 51.84%, H
6.10%, calcd for C33H40O19‚3/2H2O, C 51.62%, H 5.65%.
Acid Hyd r olysis of 2. Compound 2 (13.6 mg) was subjected
to acid hydrolysis as described for 1a to give 4′,5-dihydroxy-
7-methoxyflavonol (3.4 mg) and a sugar fraction (4.5 mg).
HPLC analysis of the sugar fraction under the same conditions
as in the case of that of 1a showed the presence of D-glucose,
D-xylose, and L-rhamnose; tR (min) 8.85 (L-rhamnose, negative
optical rotation); 10.71 (D-xylose, positive optical rotation);
15.71 (D-glucose, positive optical rotation).
Alk a lin e Meth a n olysis of 1. Compound 1 (36.5 mg) was
treated with 3% NaOMe in MeOH (4 mL) at room temperature
for 2 h. The reaction mixture was neutralized by passing
through an Amberlite IR-120B (Organo, Tokyo, J apan) column
and purified by Si gel CC, eluting initially with CHCl3 and
then with CHCl3-MeOH-H2O (20:10:1) to give 1a (23.8 mg)
and methyl 3,5-dimethoxy-4-hydroxycinnamate (7.2 mg).12
Com p ou n d 1a : pale-yellow amorphous powder; [R]24D +5.9°
(c 0.17, CHCl3-MeOH, 1:1); UV (MeOH) λmax 348 nm (log ꢀ
4.22), 268 nm (log ꢀ 4.29); UV (MeOH + 1 M NaOH) λmax 385
nm; IR (film) νmax 3376 (OH), 2929 (CH), 1656 (CdO), 1596,
1497, and 1445 (aromatic rings), 1416, 1346, 1280, 1212, 1168,
1
1136, 1070, 916, 886 cm-1; H NMR (C5D5N) δ 6.58 (1H, d, J
) 2.2 Hz, H-6), 6.56 (1H, d, J ) 2.2 Hz, H-8), 3.69 (3H, s, OMe),
8.54 (2H, d, J ) 8.8 Hz, H-2′ and H-6′), 7.41 (2H, d, J ) 8.8
Hz, H-3′ and H-5′), 6.47 (1H, d, J ) 7.6 Hz, H-1′′), 4.44 (1H,
dd, J ) 8.8, 7.6 Hz, H-2′′), 4.35 (1H, dd, J ) 8.8, 8.8 Hz, H-3′′),
3.94 (1H, dd, J ) 8.8, 8.8 Hz, H-4′′), 3.99 (1H, ddd, J ) 8.8,
6.2, 2.4 Hz, H-5′′), 4.38 (1H, dd, J ) 11.2, 2.4 Hz, H-6′′a), 3.88
(1H, dd, J ) 11.2, 6.2 Hz, H-6′′b), 5.61 (1H, d, J ) 7.8 Hz,
H-1′′′), 4.20 (1H, dd, J ) 9.0, 7.8 Hz, H-2′′′), 4.28 (1H, dd, J )
9.0, 9.0 Hz, H-3′′′), 4.32 (1H, dd, J ) 9.0, 9.0 Hz, H-4′′′), 4.00
(1H, ddd, J ) 9.0, 4.3, 2.4 Hz, H-5′′′), 4.52 (1H, dd, J ) 11.7,
2.4 Hz, H-6′′′a), 4.39 (1H, dd, J ) 11.7, 4.3 Hz, H-6′′′b), 5.18
(1H, d, J ) 1.3 Hz, H-1′′′′), 4.24 (1H, dd, J ) 3.3, 1.3 Hz, H-2′′′′),
4.29 (1H, dd, J ) 9.2, 3.3 Hz, H-3′′′′), 4.09 (1H, dd, J ) 9.2,
9.2 Hz, H-4′′′′), 4.06 (1H, dq, J ) 9.2, 5.6 Hz, H-5′′′′), 1.44 (3H,
d, J ) 5.6 Hz, Me-6′′′′); 13C NMR (C5D5N) δ 157.8 (C-2), 134.5
(C-3), 178.9 (C-4), 162.5 (C-5), 98.5 (C-6), 165.6 (C-7), 92.4 (C-
8), 106.3 (C-5a), 157.3 (C-8a), 55.8 (OMe), 122.1 (C-1′), 132.2
(C-2′), 116.3 (C-3′), 161.7 (C-4′), 116.3 (C-5′), 132.2 (C-6′), 99.9
(C-1′′), 83.8 (C-2′′), 78.4 (C-3′′), 71.2 (C-4′′), 77.4 (C-5′′), 67.5
(C-6′′), 106.1 (C-1′′′), 76.1 (C-2′′′), 78.4 (C-3′′′), 71.4 (C-4′′′), 78.8
(C-5′′′), 62.6 (C-6′′′), 102.1 (C-1′′′′), 72.1 (C-2′′′′), 72.5 (C-3′′′′),
73.9 (C-4′′′′), 69.5 (C-5′′′′), 18.4 (C-6′′′′); FABMS (positive mode)
m/z 793 [M + Na]+; FABMS (negative mode) m/z 769 [M -
H]-, 623 [M - H - rhamnosyl]-, 607 [M - H - glucosyl]-.
Acid Hyd r olysis of 1a . A solution of 1a (6.9 mg) in 1 M
HCl (dioxane-H2O, 1:1, 4 mL) was heated at 95 °C for 2 h
under an Ar atmosphere. After cooling, the reaction mixture
was neutralized by passage through an Amberlite IRA-93ZU
(Organo, Tokyo, J apan) column and chromatographed on Si
gel using a discontinuous gradient of CHCl3-MeOH (12:1 to
1:1) to give 4′,5-dihydroxy-7-methoxyflavonol (2.8 mg) and a
sugar fraction (3.3 mg). The sugar fraction was dissolved in
H2O and passed through a Sep-Pak C18 cartridge (Waters,
Milford, MA), which was then analyzed by HPLC under the
following conditions: solvent, MeCN-H2O (3:1); flow rate, 0.8
mL/min; detection, optical rotation. Identification of D-glucose
and L-rhamnose present in the sugar fraction was carried out
by comparison of their retention times and optical rotations
with those of authentic samples. tR (min) 8.86 (L-rhamnose,
negative optical rotation), 15.69 (D-glucose, positive optical
rotation).
Com p ou n d 4: amorphous powder; [R]24 -70.8° (c 0.13,
D
CHCl3-MeOH, 1:1); IR (film) νmax 3387 (OH), 2951, 2928, and
2876 (CH), 1457, 1434, 1376, 1243, 1210, 1158, 1073, 1055,
1
980, 919, 893, 863 cm-1; H NMR (C5D5N) δ 5.58 (1H, d, J )
7.8 Hz, H-1′′′), 5.29 (1H, br d, J ) 4.8 Hz, H-6), 5.26 (1H, d, J
) 7.8 Hz, H-1′′′′), 5.22 (1H, d, J ) 7.9 Hz, H-1′′), 4.92 (1H, d,
J ) 7.7 Hz, H-1′), 4.46 (1H, t-like, J ) 6.9 Hz, H-16), 4.06 (1H,
m, H-2), 3.81 (1H, m, H-3), 3.51 (2H, br s, H2-26), 2.27 (1H, q,
J ) 7.1 Hz, H-20), 2.20 (1H, m, H-15R), 1.48 (1H, m, H-15â),
1.23 (3H, d, J ) 7.1 Hz, Me-21), 0.97 (3H, s, Me-19), 0.95 (3H,
s, Me-18), 0.69 (3H, d, J ) 5.5 Hz, Me-27); 13C NMR, see Table
1; FABMS (positive mode) m/z 1087 [M + Na]+; FABMS
(negative mode) m/z 1063 [M - H]-, 931 [M - H - xylosyl]-,
901 [M - H - glucosyl]-, 769 [M - H - xylosyl - glucosyl]-,
607 [M - H - xylosyl - glucosyl × 2]-; anal. C 52.55%, H
7.92%, calcd for C50H80O24‚4H2O, C 52.81%, H 7.80%.
Acid Hyd r olysis of 4. Compound 4 (27.9 mg) was subjected
to acid hydrolysis as described for 1a to give unidentified
artifactual sapogenols (11.3 mg) and a sugar fraction (10.2 mg).
HPLC analysis of the sugar fraction under the same conditions
as in the case of that of 1a showed the presence of D-glucose,
D-galactose, and D-xylose; tR (min) 10.73 (D-xylose, positive
optical rotation); 15.74 (D-glucose, positive optical rotation);
17.22 (D-galactose, positive optical rotation).
Com p ou n d 6: amorphous powder; [R]24 -60.0° (c 0.13,
D
CHCl3-MeOH, 1:1); IR (film) νmax 3376 (OH), 2926 and 2873
(CH), 1456, 1435, 1418, 1374, 1259, 1243, 1210, 1154, 1075,
1040, 981, 919, 897, 867 cm-1; 1H NMR (C5D5N) δ 5.58 (1H, d,
J ) 7.6 Hz, H-1′′′), 5.36 (1H, br d, J ) 4.7 Hz, H-6), 5.20 (1H,
d, J ) 7.9 Hz, H-1′′), 5.17 (1H, d, J ) 7.8 Hz, H-1′′′′′), 5.12
(1H, d, J ) 7.8 Hz, H-1′′′′), 4.92 (1H, d, J ) 7.7 Hz, H-1′), 4.48
(1H, m, H-16), 4.35 (1H, dd, J ) 5.1, 3.9 Hz, H-15), 4.06 (1H,
m, H-2), 3.84 (1H, m, H-3), 3.62 (1H, dd, J ) 11.0, 3.2 Hz,
H-26eq), 3.51 (1H, dd, J ) 11.0, 11.0 Hz, H-26ax), 1.27 (3H, s,
Me-18), 1.13 (3H, d, J ) 6.6 Hz, Me-21), 0.98 (3H, s, Me-19),
0.72 (3H, d, J ) 6.4 Hz, Me-27); 13C NMR, see Table 1; FABMS
(positive mode) m/z 1249 [M + Na]+; FABMS (negative mode)
m/z 1225 [M - H]-, 1093 [M - H - xylosyl]-, 1063 [M - H -
glucosyl]-, 931 [M - H - xylosyl - glucosyl]-, 901 [M - H -
glucosyl × 2]-, 769 [M - H - xylosyl - glucosyl × 2]-, 607 [M
- H - xylosyl - glucosyl × 3]-; anal. C 52.06%, H 7.82%, calcd
for C56H90O29‚7/2H2O, C 52.13%, H 7.58%.
Com p ou n d 2: pale-yellow amorphous powder; [R]24D -47.6°
(c 0.21, CHCl3-MeOH, 1:1); UV (MeOH) λmax 348 nm (log ꢀ
4.19), 268 nm (log ꢀ 4.25); UV (MeOH + 1 M NaOH) λmax 388
nm; IR (film) νmax 3377 (OH), 2930 (CH), 1656 (CdO), 1597,
1498, and 1445 (aromatic rings), 1347, 1280, 1213, 1168, 1138,
1
1065, 917, 887 cm-1; H NMR (C5D5N) δ 6.53 (1H, d, J ) 2.2
Acid Hyd r olysis of 6. Compound 6 (36.6 mg) was subjected
to acid hydrolysis as described for 1a to give 10 (4.6 mg) and
a sugar fraction (12.8 mg). HPLC analysis of the sugar fraction
under the same conditions as in the case of that of 1a showed
the presence of D-glucose, D-galactose, and D-xylose; tR (min)
Hz, H-6), 6.57 (1H, d, J ) 2.2 Hz, H-8), 3.69 (3H, s, OMe),
8.55 (2H, d, J ) 8.8 Hz, H-2′ and H-6′), 7.36 (2H, d, J ) 8.8
Hz, H-3′ and H-5′), 6.42 (1H, d, J ) 7.7 Hz, H-1′′), 4.44 (1H,
dd, J ) 8.7, 7.7 Hz, H-2′′), 4.35 (1H, dd, J ) 8.7, 8.7 Hz, H-3′′),