D.N. Nicolaides et al. / European Journal of Medicinal Chemistry 39 (2004) 323–332
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1690, 1580; H NMR: d 0.99 (s, 3H), 1.00 (s, 3H), 1.08 (s,
faster moving band compound 21I (43 mg, 31%), mp 106–
3H), 1.12 (s, 6H), 1.13 (s, 3H), 1.41 (t, 3H, J = 7.6), 1.60 (s,
3H), 1.61 (s, 3H), 1.60–1.73 (m, 2H), 1.82–2.04 (m, 2H),
2.13–2.33 (m, 2H), 2.42–2.58 (m, 2H), 4.53 (q, 2H, J = 7.6),
5.50 (d, 1H, J = 5.09), 6.40 (s, 1H), 6.75 (d, 1H, J = 5.09),
7.54-7.67 (m, 2H), 7.79 (d, 1H, J = 7.6), 8.35 (d, 1H, J = 7.6);
13C NMR: d 9.5, 9.6, 13.8, 16.3, 16.4, 16.6, 16.7, 21.1, 26.4,
28.8, 28.9, 30.8, 31.2, 54.2, 54.6, 54.9, 55.0, 61.6, 62.9, 72.2,
77.8, 90.7, 91.3, 102.9, 104.5, 112.3, 122.9, 123.4, 123.5,
125.9, 128.9, 129.3, 146.2, 154.0, 154.1, 158.4, 166.6, 166.9,
167.3, 177.9, 178.4; EIMS: m/z 744 (M+, 51%), 743 (43),
547 (30), 546 (40), 350 (55), 335 (74), 312 (45), 83 (100);
[a]D –39.9° (c 0.78, CHCl3). Anal. C41H44O13 (CH).
108 °C (ether–hexane); IR (DCM, cm–1) 3020, 1780, 1745,
1
1735, 1720, 1690, 1580; H NMR: d 0.98 (s, 3H), 1.03 (s,
3H), 1.08 (s, 3H), 1.41 (t, 3H, J = 7.6), 1.58 (s, 3H), 1.67 (s,
3H), 1.82–1.95 (m, 2H), 1.96–2.11 (m, 1H), 2.35–2.50 (m,
1H), 4.53 (q, 2H, J = 7.6), 5.65 (d, 1H, J = 3.81), 6.35 (s, 1H),
6.56 (d, 1H, J = 3.81), 7.36 (t, 1H, J = 7.6), 7.51–7.67 (m,
3H), 7.80 (d, 1H, J = 7.6), 7.91 (d, 1H, J = 7.6), 7.96 (s, 1H),
8.39 (d, 1H, J = 7.6); 13C NMR: d 9.6, 14.2, 16.6, 16.7, 21.0,
23.1, 28.7, 30.9, 54.4, 54.9, 60.3, 65.1, 73.4, 78.1, 89.9,
101.8, 102.9, 112.4, 123.1, 123.4, 123.6, 125.2, 125.9, 128.0,
128.6, 129.2, 129.8, 131.1, 133.4, 134.4, 146.1, 153.7, 154.2,
158.3, 164.1, 171.1, 172.4, 184.4; EIMS: m/z 702 (M+, 58%),
548 (40), 505 (30), 490 (55), 366 (75), 350 (55), 335 (60),
156 (70),139 (100); MALDIHRMS (DHB): m/z 725.1760
[M + Na]+. C38H35ClNaO11 requires m/z 725.1760.
5.1.12. Ethyl (cis)-3-hydroxy-4{[(4,7,7-trimethyl-3-oxo-
2-oxabicyclo[2.2.1]hept-1-yl)carbonyl]oxy}-3,4-dihydro-2H
6H-benzo[f]pyrano[2,3-h]chromene-8-carboxylate 20
It was obtained from the above reaction of compound 16,
after the elution of compound 19II, (0.18 g, 67%), mp 189–
191 °C (ether–hexane); IR (cm–1) 3520, 1790, 1740, 1725,
,
Compound 21II was eluted next (37 mg, 25%), mp 88–
90 °C (ether–hexane); IR (DCM, cm–1) 3020, 1780, 1750,
1
1730, 1715, 1690, 1575; H NMR: d 0.98 (s, 3H), 1.03 (s,
3H), 1.09 (s, 3H), 1.41 (t, 3H, J = 7.6), 1.58 (s, 3H), 1.65 (s,
3H), 1.78–1.98 (m, 2H), 2.01–2.20 (m, 1H), 2.29–2.46 (m,
1H), 4.53 (q, 2H, J = 7.6), 5.63 (d, 1H, J = 3.81), 6.36 (s, 1H),
6.58 (d, 1H, J = 3.81), 7.36 (t, 1H, J = 7.6), 7.50–7.67 (m,
3H), 7.80 (d, 1H, J = 7.6), 7.91 (d, 1H, J = 7.6), 7.96 (s, 1H),
8.40 (d, 1H, J = 7.6); 13C NMR: d 9.6, 14.2, 16.6, 16.7, 23.4,
24.1, 28.8, 31.0, 54.7, 54.9, 60.3, 64.9, 73.1, 77.9, 90.8,
102.6, 104.6, 112.4, 123.1, 123.4, 123.7, 125.9, 126.3, 128.0,
128.8, 129,.2, 129.7, 131.1, 133.4, 134.6, 146.1, 154.1,
154.5, 158.5, 164.0, 166.3, 171.1, 180.0; EIMS: m/z 702
(M+, 5%), 702 (12), 548 (4), 489 (15), 350 (5), 335 (15), 156
(20), 139 (100); MALDIHRMS (DHB): m/z 725.1752 [M +
Na]+. C38H35ClNaO11 requires m/z 725.1760.
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1690, 1580; H NMR: d 0.98 (s, 3H), 1.08 (s, 3H), 1.10 (s,
3H), 1.41 (t, 3H, J = 7.6), 1.67 (s, 6H), 1.85–1.97 (m, 2H),
2.08–2.21 (m, 1H), 2.41–2.58 (m, 1H), 2.98 (brs, 1H), 4.25
(d, 1H, J = 5.08), 4.52 (q, 2H, J = 7.6), 6.36 (s, 1H), 6.64 (d,
1H, J = 5.08), 7.52–7.64 (m, 2H), 7.76 (d, 1H, J = 7.6), 8.35
(d, 1H, J = 7.6); 13C NMR: d 9.6, 13.9, 16.5, 16.7, 20.2, 26.5,
28.9, 31.2, 54.4, 54.9, 62.9, 64.5, 71.7, 79.5, 91.3, 102.9,
104.2, 111.8, 123.2, 123.4, 123.7, 125.8, 128.9, 129.2, 146.4,
154.6, 154.7, 158.8, 167.4, 168.8, 178.2; ESIMS: m/z 565 [M
+ H]+, 587 [M + Na]+, 563 [M – H]+, 599 [M + Cl]+. Anal.
C31H32O10 (CH).
5.1.13. Ethyl (trans)-(3R,4S or 3S,4R)-4-[(3-chlorobenzoyl)
oxy]2,2-dimethyl-6-oxo-3-{[(4,7,7-trimethyl-3-oxo-2-oxa-
bicyclo[2.2.1]hept-1-yl)carbonyl]oxy}-3,4-dihydro-2H,
6H-benzo[f]pyrano[2,3-h]chromene-8-carboxylates 21I
and ethyl (trans)-(3S,4R or 3R,4S)-4-[(3-chlorobenzoyl)-
oxy]2,2-dimethyl-6-oxo-3-{[(4,7,7-trimethyl-3-oxo-2-oxa-
5.2. Biology
5.2.1. Competition of the tested compounds with DMSO
for hydroxyl radicals [21]
bicyclo[2.2.1]hept-1-yl)carbonyl]oxy}-3,4-dihydro-2H,6H
benzo[f]pyrano[2,3-h]chromene-8-carboxylates 21II
-
The hydroxyl radicals generated by the Fe3+/ascorbic acid
system, were detected according to Nash [21], by the deter-
mination of formaldehyde produced from the oxidation of
DMSO. The reaction mixture contained EDTA (0.1 mM),
Fe3+ (167 µM), DMSO (33 mM) in phosphate buffer
(50 mM, pH 7.4), the tested compounds and ascorbic acid
(10 mM).After 30 min of incubation (37 °C) the reaction was
stopped with CCl3COOH (17% w/v).
To a solution of compound 17 (0.105 g, 0.20 mmol) in a
mixture of dry DCM (4.5 ml) and dry pyridine (0.5 ml)
(1S)-(–)-camphanic chloride (65 mg, 0.30 mmol) was added
at 0 °C. The mixture was stirred for 24 h at rt, an additional
amount of the chloride (65 mg, 0.30 mmol) was added and
the mixture was stirred for further 48 h. The mixture was
concentrated in a rotary evaporator, water (10 ml) was added
to the residue and the mixture was extracted with chloroform
(20 ml). The organic layer was washed with water (10 ml),
then with brine (10 ml) and it was dried over Na2SO4. The
solvent was evaporated in vacuum and the residue was sepa-
rated by column chromatography (DCM–ethyl acetate 20:1)
to give mixture of compounds 21I, 21II (81 mg, 56%). The
unreacted starting compound 17 (40 mg, 39%) was eluted
next. The mixture of compounds 21I,II was further separated
by ptlc (silica gel, hexane–ethyl acetate 3:1) to give from the
5.2.2. Interaction of the tested compounds with
1,1-diphenyl-2-picryl-hydrazyl (DPPH) stable free radical
To a solution of DPPH (0.1 mM) in absolute ethanol an
equal volume of the compounds (0.1, 0.2, 0.5 mM) dissolved
in ethanol was added. As control solution ethanol was used.
After 20 and 60 min at rt the absorbance was recorded at
517 nm.