1202 Beate Hager et al.
(s, 3-OCH3), 3.894 (s, 1-OCH3), 3.889 (s, 8-OCH3), 3.27
(t, J = 7.8 Hz, 6-CH2-CH2-), 3.14 (t, J = 7.8 Hz, 6-CH2-CH2-)
ppm; 13C NMR (125 MHz, d, DMSO-d6, 30ꢁC): 183.2 (C10), 179.8
(C9), 163.4 (C3), 161.1 (C1), 160.7 (Py-C4), 159.0 (C8), 146.9 (C6),
141.9 (Py-C2,6), 135.5 (C4a), 133.9 (C10a), 126.8 (Py-C3,5), 121.7
(C8a), 119.2 (C7), 118.2 (C5), 117.5 (C9a), 105.0 (C2), 102.3 (C4),
56.4 (1-OCH3 or 8-OCH3), 56.3 (8-OCH3 or 1-OCH3), 55.9
might be considered as an alternative treatment concept
minimizing damage of pilosebaceous follicles, which has been
described for ALA-PDT (40,41).
In the present communication, we describe for the first
time the synthesis and preliminary testing of two cationic
hypericin derivatives. Attachment of charged substituents at
the two x-methyl groups of 1 provides unperturbed photo-
sensitization of singlet oxygen and ⁄ or reactive oxidizing
species as assessed previously (11); as quaternary salt
moieties, the N,N,N-trimethyl-anilinum and the N-methyl-
pyridinium ions were chosen. Photobactericidal activity was
assessed using P. acnes.
(3-OCH3),
35.7
(6-CH2-CH2-),
35.0
(6-CH2-CH2-)
ppm;
IR (KBr): ꢀm = 3377, 3215, 3076, 2925, 2843, 1663, 1634, 1601,
1561, 1501, 1465, 1351, 1327, 1243, 1207, 1130, 1073, 1019, 944,
875, 848, 756 cm)1; UV-Vis (MeOH + 10% CHCl3): kmax (rel.
intensity) = 256 (94), 262 (97), 276 (100), 405 (24) nm; MS (ESI-
MS; MeOH:CHCl3 = 1:1 + 1% HCOOH; c ꢀ 1 mgÆcm)3; positive
ion mode): m ⁄ z = 404 (M+H)+
.
6-(4-(Dimethylamino)phenethyl)-1,3,8-trimethoxy-anthraquinone (6).
Prepared by hydrogenation of 4 in analogy to 5 in 95% yield,
C27H27NO5: m.p. 81-84ꢁC; 1H NMR (500 MHz, CDCl3, 30ꢁC):
d = 7.65 (d, J = 6.5 Hz, Ph-H3,5), 7.60 (s, ar-H5), 7.31 (m, 3H,
Ph-H2,6 and ar-H7), 7.00 (s, ar-H4), 6.78 (s, ar-H2), 3.98 (s, 1-
OCH3 or 3-OCH3), 3.97 (s, 3-OCH3 or 1-OCH3), 3.94 (s, 8-OCH3),
3.14 (s, 6H, N-CH3), 3.03 (s, 4H, 6-CH2-CH2-) ppm; 13C NMR
(125 MHz, d, CDCl3, 30ꢁC): 184.3 (C10), 181.7 (C9), 164.0 (C3),
161.9 (C1), 160.0 (C8), 147.2 (Ph-C1), 143.4 (C6), 141.3 (C4a), 136.5
(C10a), 134.8 (Ph-C4), 130.6 (C7), 122.4 (C8a), 118.5 (C9a), 120.9
(Ph-C3,5) 119.0 (C5), 118.6 (C4), 105.4 (C2), 102.2 (Ph-C2,6), 56.7
(1-OCH3 od. 3-OCH3), 56.6 (3-OCH3 od. 1-OCH3), 56.0 (8-OCH3),
46.7 (N-CH3), 37.8 (6-CH2-CH2-), 36.5 (6-CH2-CH2-) ppm; UV-Vis
(MeOH + 10% CHCl3): kmax (rel. intensity) = 228 (100), 270 (98),
404 (14) nm; IR (KBr): ꢀm = 3375, 3215, 3074, 2926, 2854, 1668,
1597, 1515, 1459, 1325, 1244, 1203, 1162, 1130, 1070, 1018, 946,
754 cm)1; MS (ESI-MS; MeOH; c ꢀ 1 mgÆcm)3; positive ion mode):
MATERIALS AND METHODS
General. The products were characterized using m.p. (Kofler micro-
scope, Reichert), 1H NMR (Bruker DPX 200 and DRX
500 MHz—signal assignments were proven by means of 2D spectra)
(NOESY, HMBC), IR (Bruker Tensor 27, KBr), MS (Thermofinnigan
LCQ Deca XP Plus and Agilent MSD Trap SL), fluorescence (Varian
Cary Eclipse fluorescence instrument), and UV-Vis data (Varian Cary
100 Bio). Fluorescence quantum yields were calculated according to
the comparative method of Williams et al. (42) using hypericin (1) as
standard sample. The production of singlet oxygen ⁄ oxidizing species
by 11–14 was monitored by bilirubin-IXa-degradation according to
Ref. (43). The long-wavelength ‘‘hypericinic’’ absorption band inten-
sities of 1 and the four compounds were made equal by adjusting
concentrations to provide comparable light absorptions for all
compounds investigated. Emodin was hydrolytically extracted from
Cortex frangulae as described in Ref. (44) and 2 was prepared as
described in Ref. (45).
(Z)- and (E)-6-(2-(Pyridin-4-yl)vinyl)-1,3,8-trimethoxy-anthraquinone
(3). A suspension of 2 (0.50 g; 0.77 mM), dried K2CO3 (0.20 g;
1.45 mM), and 18-crown-6 (0.15 g; 0.57 mM) in 30 mL dry CH2Cl2
was refluxed under argon for 15 min. To this dark-blue ylide solution
pyridine-4-carbaldehyde (1.66 g; 15.5 mM) dissolved in 30 mL dry
CH2Cl2 was added drop-wise in three portions with 40 min reflux
intermissions in between. After refluxing for further 30 min, the
reaction mixture was filtered, diluted with 50 mL CH2Cl2, and
extracted with brine. Re-extraction with CH2Cl2, drying of the
combined organic layers over Na2SO4, and evaporation resulted in a
yellow colored oil, which crystallized upon addition of diethyl ether
yielding 0.27 g (87%) of 3, C24H19NO5: TLC (silica 60;
CHCl3:MeOH = 15:1 (v:v)): Rf = 0.51 (E)-isomer, 0.46 (Z)-isomer;
m.p. 176-179ꢁC; 1H NMR (500 MHz, DMSO-d6, 30ꢁC): (E)-isomer:
d = 8.61 (d, J = 5.8 Hz, Py-H2,6), 7.94 (s, ar-H5), 7.77 (s, ar-H7),
7.72 (d, J = 16.5 Hz, 6-CH = CH-), 7.64 (d, J = 5.8 Hz, Py-H3,5),
7.57 (d, J = 16.5 Hz, 6-CH=CH-), 7.20 (d, J = 2.3 Hz, ar-H4), 7.00
(d, J = 2.3 Hz, ar-H2), 3.99 (s, ar-OCH3), 3.95 (s, ar-OCH3), 3.91 (s,
ar-OCH3) ppm; (Z)-isomer: d = 8.51 (d, J = 5.8 Hz, Py-H2,6), 7.50
(s, ar-H5), 7.29 (s, ar-H7), 7.24 (d, J = 5.8 Hz, Py-H3,5), 7.14 (d,
J = 2.3 Hz, ar-H4), 6.98 (d, J = 2.3 Hz, ar-H2), 6.96 (d,
J = 12.3 Hz, 6-CH=CH-), 6.86 (d, J = 12.3 Hz, 6-CH=CH-), 3.92
(s, ar-OCH3), 3.89 (s, ar-OCH3), 3.70 (s, 8-OCH3) ppm; UV-Vis
(MeOH + 10% CHCl3): kmax (rel. intensity) = 300 (100), 415 (30)
m ⁄ z = 447 (M+H)+
.
1,3,8-Trihydroxy-6-(2-(pyridin-4-yl)ethyl)-10H-anthracen-9-one (7). To
a refluxing solution of 5 (70 mg; 0.17 mM) in 10 mL glacial acetic acid
SnCl2x2H2O (307 mg) dissolved in 5 mL aqueous HBr solution (47%)
was added under argon. The reaction mixture was further refluxed for
1 h, cooled to room temperature, and poured into ice. The suspension
was centrifuged at 5000 g, the residue washed with distilled H2O (3x),
and dried under vacuum, which yielded 50.1 mg (85%) of 7,
C21H17NO4: 1H NMR (500 MHz, DMSO-d6, 30ꢁC): d = 12.35 (s, 1-
OH or 3-OH), 12.22 (s, 8-OH or 1-OH), 10.82 (s, 8-OH), 8.54 (d,
J = 4.1 Hz, Py-H2,6), 7.43 (d, J = 4.1 Hz, Py-H3,5), 6.86 (s, ar-H5),
6.76 (s, ar-H7), 6.44 (s, ar-H4), 6.24 (s, ar-H2), 4.31 (s, -CH2-), 3.00 (d,
J = 7.2 Hz, 6-CH2-CH2-), 2.97 (d, J = 7.2 Hz, 6-CH2-CH2-) ppm;
UV-Vis (DMSO): kmax (rel. intensity) = 261 (75), 358 nm (100); MS
(ESI-MS; MeOH:CHCl3 = 1:1 + 1% HCOOH;
.
c
ꢀ
1 mgÆcm)3
;
positive ion mode): m ⁄ z = 348 (M+H)+
2-(4-(Dimethylamino)phenethyl)-4,5,7-trihydroxy-anthracen-10(9H)-
one (8). Prepared in analogy to 7 in 79% yield, C24H23NO4): 1H NMR
(200 MHz, DMSO-d6, 30ꢁC): d = 12.37 (s, 1-OH or 3-OH), 12.20 (s,
3-OH or 1-OH), 10.80 (s, 8-OH), 7.06 (d, J = 8.4 Hz, Ph-H3,5), 6.85
(s, ar-H5), 6.72 (s, ar-H7), 6.65 (d, J = 8.4 Hz, Ph-H2,6), 6.43 (s, ar-
H4), 6.23 (s, ar-H2), 4.32 (s, -CH2-), 2.84 (m, 10H, 6-CH2-CH2- + -
CH3) ppm; UV-Vis (DMSO): kmax (rel. intensity) = 262 (100),
362 nm (65); MS (ESI-MS; MeOH; c ꢀ 1 mgÆcm)3; positive ion mode):
m ⁄ z = 390 (M+H)+
.
1,3,4,6,8,15-Hexahydroxy-10,13-bis(2-(pyridin-4-yl)ethyl)-dibenzo
[ao]perylen-7,16-dione (9). A mixture of (172 mg; 0.50 mM),
7
FeSO4 · 7H2O (6.4 mg; 0.02 mM), pyridine-N-oxide (254 mg;
2.67 mmol), 2.5 mL abs. pyridine, and 0.25 mL piperidine was
stirred for 1 h at 115ꢁC under argon and light protection. After
cooling 8.4 mL 2M HCl was added and the mixture stirred for
30 min at room temperature. The precipitate was centrifuged at
5000 g, washed with 3% HCl (3x) and distilled H2O (3x), and dried
under vacuum over P2O5 and exclusion of light resulting in
9, C42H28N2O8: UV-Vis (methanol): kmax (rel. intensity) = 375
(100), 545 (76), 582 nm (70). Due to its light sensitivity this
intermediate was immediately photocyclized without further charac-
terization.
10,13-bis(2-(4-(Dimethylamino)phenethyl)-1,3,4,6,8,15-hexahydroxy-
dibenzo[ao]perylen-7,16-dione (10). Prepared in analogy to 9,
C48H40N2O8: UV-Vis (methanol): kmax (rel. intensity) = 375 (94), 550
(99), 575 nm (100). Due to its light sensitivity this product was
immediately photocyclized.
nm;
MS
(ESI-MS;
MeOH:CHCl3 = 1:1 + 1%
HCOOH;
c ꢀ 1 mgÆcm)3; positive ion mode): m ⁄ z = 402 (M+H)+
.
(E)-6-(4-(Dimethylamino)styryl)-1,3,8-trimethoxyanthraquinone (4).
Preparation according to the procedure given above by reacting 2 with
4-dimethylamino-benzaldehyde (1.15 g; 7.7 mM) provided 90 mg (28%)
of 4, C27H25NO5: Properties were found to be identical with those
described in Ref. (46).
6-(2-(Pyridin-4-yl)ethyl)-1,3,8-trimethoxy-anthraquinone (5). Com-
pound 3 (100 mg; 0.25 mM) was dissolved in 250 mL methanol.
Thereafter, 25 mL CHCl3 and 30 mg Pd ⁄ C (10%) were added. After
purging with argon for 15 min the solution was stirred under H2 and
ambient conditions for 20 h. After filtration and evaporation 97 mg
(96%) of 5 was obtained, C24H21NO5: m.p. 149-153ꢁC; 1H NMR
(500 MHz, DMSO-d6, 30ꢁC): d = 8.80 (d, J = 4.9 Hz, Py-H2,6),
7.94 (d, J = 4.9 Hz, Py-H3,5), 7.57 (s, ar-H5), 7.45 (s, ar-H7), 7.16
(d, J = 2.2 Hz, ar-H4), 6.98 (d, J = 2.2 Hz, ar-H2), 3.93