+
+
1
40 [272 – C H O ] , and 122 [272 – C H O ] also suggested the location of the sugar moiety in ring A. The ion peaks
5 9 4 5 10 5
+
formed at m/z 210 [M – 272] , 182 [C – C fission], and 168 [C9,O – C2,3 fission] supported the existence of two hydroxyl
9
,O
3,4
1
and one methoxy groups in ring B [9]. The H NMR spectrum of 2 exhibited two one-proton broad signals at ꢂ 7.45 and ꢂ 7.29
ascribed to p-coupled H-3ꢀ and H-6ꢀ, establishing the 2,4,5-trioxygenated ring B [10, 11]. AnABX system with double doublets
at ꢂ 5.31 (J = 2.7, 13.5 Hz), 2.97 (J =2.7, 13.5 Hz), and 2.81 (J = 13.5, 16.9 Hz) was characteristic of H-2ꢁ, H-3ax, and H-3eq
of the flavanone moiety [7]. Aone-proton doublet at ꢂ 5.28 (J = 7.1 Hz) was ascribed to the anomeric proton H-1ꢀꢀ. Aone-proton
doublet at ꢂ 4.24 with coupling constant 7.2 Hz was ascribed to H-2ꢀꢀ. Two one-proton doublet signals at ꢂ 3.05 (J = 10.8 Hz)
and ꢂ 3.01 (J = 10.8 Hz) were attributed correspondingly to oxygenated methylene protons H -5ꢀꢀa and H -5ꢀꢀb, respectively.
2
2
The remaining carbinol protons of the sugar units appeared as multiplets at ꢂ 4.05 (1H) and ꢂ 3.45 (1H). A three-proton broad
1
3
signal at ꢂ 3.62 was ascribed to methoxyl protons attached at C-4ꢀ. The C NMR spectrum of 2 displayed important signals for
the C-4 carbonyl carbon (ꢂ 193.14), flavanone carbons between ꢂ 172.63–37.01, anomeric carbons at ꢂ 101.23 (C-1ꢀ), and
sugar carbons between ꢂ 73.54–61.17. The DEPT spectrum of 2 showed the presence of one methoxyl, two methylene, seven
methine, and eleven quaternary carbons. In the HMBC spectrum of 2, H-2 correlated with C-1ꢀ, C-2ꢀ, C-6ꢀ, and C-4; H-3ꢀ
interacted with C-1ꢀ, C-2ꢀ, and C-4ꢀ; and H-1ꢀꢀ interacted with C-2ꢀꢀ, C-3ꢀꢀ, and C-7. In the CD spectrum, a negative cotton
effect at 303 nm (ꢄꢅ– 12.9) and a positive cotton effect at 335 (ꢄꢅ+ 7.15) indicated the S-configuration at C-2 [12, 13]. Acid
hydrolysis of flavonoid glycosides gave flavanone and sugar as xylose (TLC comparable). On the basis of spectral data
analyses and chemical reactions, the structure of 2 has been elucidated as 5,6,7,8,2ꢀ,5ꢀ-hexahydroxy-4ꢀ-methoxy- flavanone-7-
ꢁ
-D-xylopyranoside.
EXPERIMENTAL
General Procedure. Melting points were determined on a Perfit melting point apparatus and are uncorrected. FT IR:
1
Jasco FT/IR-5000; UV: Lambda Bio 20 spectrophotometer, MeOH; H NMR (400 MHz): Advance DRY 400, Bruker
1
3
Spectrospin, CDCl3; C NMR (75 MHz): Advance DRY 100, Bruker Spectrospin, CDCl with TMS as an internal standard;
3
MS: FAB ionization on JEOL-JMS-DX 303; CC: Silica gel (Qualigens), 60–120 mesh; TLC: silica gel G (Qualigens). Spots
were visualized by exposure to iodine vapors, UV radiation, and by spraying reagents.
Plant Material. The flowers of Punica granatum were purchased from the Khari Baoli Market of Delhi and identified
by Dr. M. P. Sharma, taxonomist, Department of Botany, Jamia Hamdard, New Delhi. A voucher specimen, No. PRL/JH/05/21,
was deposited in the Herbarium of the Phytochemical Research Laboratory, Faculty of Pharmacy, Jamia Hamdard, New Delhi.
Extraction and Isolation. The dried flowers (800 g) were coarsely powdered and exhaustively extracted with methanol.
The combined extracts were concentrated on a steam-bath and dried under reduced pressure to get 420 g of dark brown mass.
The viscous dark brown mass was dissolved in a little quantity of methanol and adsorbed on silica gel (60–120 mesh) for the
preparation of slurry. It was dried in air and chromatographed over a silica gel column packed in petroleum ether. The column
was eluted with petroleum ether, chloroform, and methanol successively in order of increasing polarity.
Punicaflavanol (1). Elution of the column with chloroform–methanol (19:1) mixture gave pale yellow crystals of 1,
recrystallized from methanol, 825 mg (0.103% yield), mp 258–260ꢆC; CD (c 0.26, MeOH): (ꢄꢇ301 – 11.2), (ꢄꢇ301 + 6.41);
UV (MeOH, ꢈmax, nm): 281, 363 (log ꢇ 5.3, 2.6); UV (MeOH + NaOMe, ꢈmax, nm): 279, 329 (log ꢇ 2.7, 3.6); UV (MeOH + AlCl3,
ꢈmax, nm): 301, 374 (log ꢇ 5.6, 2.4); UV (MeOH + AlCl +HCl, ꢈ , nm): 293, 362 (log ꢇ 5.4, 2.5); UV (MeOH + NaOAc,
3
max
–1
ꢈmax, nm): 316, 381 (log ꢇ 3.9, 1.8); UV (MeOH + NaOAc + H BO , ꢈmax, nm): 293, 364 (log ꢇ 4.1, 1.8); IR (KBr, ꢉmax, cm ):
561, 3509, 3136, 2922, 2855, 1696, 1593, 1387, 1296, 1207, 1095; H NMR (DMSO-d , ꢂ, ppm, J/Hz): 7.30 (1H, br.s, H-6ꢀ),
.32 (1H, dd, J = 2.5, 13.1, H-2ꢁ), 3.62 (3H, br.s, OMe), 2.97 (1H, dd, J = 2.5, 13.1, H-3ax), 2.81 (1H, dd, J = 13.1, 17.2,
H-3eq); C NMR (DMSO-d ): see Table 1; +ve FAB MS m/z (rel. int.): 366 [M] (C H O ) (13.6), 351 (18.5), 338 (29.8),
3
3
1
3
5
6
1
3
+
6
16 14 10
3
23 (26.6), 211 (16.3), 188 (36.1), 184 (15.3), 182 (21.7), 178 (37.3), 155 (26.2), 140 (23.7), 77 (100).
Granatumflavanyl Xyloside (2). Elution of the column with chloroform–methanol (23:2) mixture gave light yellow
crystals of 2, recrystallized from methanol, 630 mg (0.078% yield), mp 252–254ꢆC; UV (MeOH, ꢈmax, nm): 277, 363
(
log ꢇ 5.7, 2.6); UV (MeOH + NaOMe, ꢈmax, nm): 282, 341 (log ꢇ 2.3, 2.1); UV (MeOH + AlCl , ꢈmax, nm): 291, 374 (log ꢇ 5.9,
3
3
.1); UV (MeOH + NaOAc, ꢈ , nm): 299, 386 (log ꢇ 1.3, 0.7); UV (MeOH + NaOAc + H BO , ꢈ , nm): 289, 368 (log ꢇ 1.3,
max 3 3 max
–1
1
0.8); IR (KBr, ꢉmax, cm ): 3373, 3160, 2928, 1700, 1593, 1445, 1397, 1338, 1199, 1094, 1040, 983, 923; H NMR (DMSO-d ,
6
ꢂ, ppm, J/Hz): 7.45 (1H, br.s, H-3ꢀ), 7.29 (1H, br.s, H-6ꢀ), 5.31 (1H, dd, J = 2.7, 13.5, H-2ꢁ), 5.28 (1H, d, J = 7.1, H-1ꢀꢀ), 4.24
203