888
S.A.M. Hussein et al. / Phytochemistry 64 (2003) 883–889
345 ion: [345-CH3]ꢀ at m/z=330; MS/MS of the 330
ion: [330-CH3]ꢀ at m/z=315. Complete acid hydrolysis
(22 mg of 4 refluxed with 10 ml aqueous methanolic,
1:1, 2 N HCl, at 100 ꢁC, for 7 h), followed by removal of
MeOH under reduced pressure and extraction by ethyl
acetate, washing of the organic layer with water, fil-
tration through anhydrous Na2SO4, and dryness in
vacuum afforded aglycone 4a: Rf-values: UV lMmaexOH nm:
Table 1; ESI-MS of (4a): negative molecular ion [M–
3.2.3. Myricetin-3,5,30,-trimethyl ether (11)
MeOH
max
Rf-values (Table 1); UV l
nm: Table 1; ESI-MS
negative molecular ion: m/z=359 [M–H]ꢀ and an [M-
CH3]ꢀ ion at m/z=344; MS/MS: of the 344 ion:
[344+H-CH3]ꢀ; at m/z=330; MS/MS of the 330 ion:
[330-CH3]ꢀ at m/z=315; complete acid hydrolysis (8 mg
of 11 refluxed with 5 ml aqueous methanolic, 1:1, 2 N
ꢁ
HCl, at 100 C, for 7 h): no changes. Hydrolytic clea-
vage of 11: 19 mg were refluxed with conc. HI (3 ml)
and phenol (19 mg), over a heating mantel, for 0.5 h,
followed by dilution with excess of saturated NaHSO3
aqueous solution and extraction of the cold reaction
mixture with ethyl acetate, washing of the organic phase
with bidistilled water, filtration through anhydrous
Na2SO4 and dryness in vacuum, afforded the dether-
ification product, myricetin, 11a (7 mg): Rf-values:
Table 1; UV lMmaexOH nm: Table 1; 1H NMR of 11: ꢀ ppm:
6.35 (d, J=2.0 Hz, H-6), 6.48 (d, J=2.0 Hz, H-8), 7.19
(broad s, H-20), 7.20 (broad s, H-60), 3.66 (s, OMe), 3.84
(s, OMe), 3.88 (s, OMe). EI-MS of 11: m/z (rel. int.): 360
(100%) [M]+, 359 (95%) [M–H]+, 342 (30%) [M-18]+,
343 (22%) [M-17]+, 182 (27%) [A1]+, 183 (20%)
[A1+H]+, 167 (94%) [B2]+ and 139 (21%) [B2-28 ]+.
13C NMR of 11: Table 2.
1
H]ꢀ: m/z=345; H NMR of (4a): ꢀ ppm: 6.05 (s, H-6),
7.75 (d, J=2.5 Hz, H-20), 6.88 (d, J=8.0 Hz, H-50), 7.50
(dd, J=8.0 Hz and 2.5 Hz, H-60), 3.74 (s, OMe), 3.70 (s,
OMe); EI-MS of 4a: m/z (rel. int.): 346 [M]+ (76), 331
[M-15]+ (100), 345 [M-1]+ (20), 182 [A1]+ (64), 167
[A1-15]+ (33), 139 [M-43]+ (28), 137 [B2]+ (36), 109 [B2-
28]+ (22); Hydrolytic cleavage of 4a: 11 mg were
refluxed with conc. HI (3 ml) and phenol (11 mg), over a
heating mantel, for 0.5 h, followed by dilution with
excess of saturated NaHSO3 aqueous solution and
extraction of the cold reaction mixture with ethyl ace-
tate, washing of the organic phase with bidistilled water,
filtration through anhydrous Na2SO4 and dryness in
vacuum, afforded a chromatographically pure sample (4
mg) of a dark brown sample of the detherification pro-
duct 4b: Rf-values: UV l
MeOH
max
nm: Table 1. b-Glucosi-
dase hydrolysis of 4: 5 mg, incubated in an acetate
buffer of pH 5.2, for 24 h, at 37 ꢁC yielded 4a. 1H NMR
of 4: ꢀ ppm: 6.10 (s, H-6), 7.75 (d, J=2.5 Hz, H-20), 6.92
(d, J=8.0 Hz, H-50), 7.68 (dd, J=8.0 Hz and 2.5 Hz, H-
6000), 3.70 (s, OMe), 3.74 (s, OMe), 4.35 (d, J=8 Hz, H-
1 ), 3.15–3.37 (overlapped sugar protons). 13C NMR of
4: Table 2.
Acknowledgements
The authors wish to express their deep gratitude to
Professor Dr. M. Linscheid, Institut fur Chemie, Hum-
boldt-Universitat zu Berlin, Germany, for the ESI-MS
measurements.
3.2.2. Gossypetin-3,5-dimethyl ether (10)
MeOH
max
Rf-values (Table 1); UV l
nm: Table 1; ESI-MS
References
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the 330 ion: [330-CH3]ꢀ at m/z=315; complete acid
hydrolysis (11 mg of 10 refluxed with 5 ml aqueous
methanolic, 1:1, 2 N HCl, at 100 ꢁC, for 7 h): no
changes. Hydrolytic cleavage of 10: 16 mg were
refluxed with conc. HBr (40%, 3 ml), over a heating
mantel, for 0.5 h, followed by dilution with excess
water and extraction of the cold reaction mixture with
ethyl acetate, washing of the organic phase with bidis-
tilled water, filtration through anhydrous Na2SO4 and
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345 (95%) [M–H]+, 328 (34%) [M-18]+, 329 (32%)
[M-17]+, 182 (32%) [A1]+, 183 (24%) [A1+H]+, 137
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