Preparation of 1,8-Di-O-alkylaloe-emodins and 15-amino-, 15-thiocyano-, and 15-selenocyanochrysophanol derivatives from aloe-emodin and studying their cytotoxic effects

Article abstract of DOI:10.1248/cpb.56.497

1,8-Di-O-alkylaloe-emodin derivatives (namely, methyl-, propyl-, hexyl-, dodecyl-, and octadecyl) were synthesized from naturally occurring aloe-emodin. Further, derivatives having various substituents such as diethylamino, pyrrolidinyl, piperidinyl, methylpiperazinyl, imidazolyl, thiocyano and selenocyano groups at the 15 position of chrysophanol and 1,8-di-O- hexylchrysophanol from aloe-emodin were synthesized. The cytotoxic effects of these derivatives on less P-glycoprotein (P-gp)-expressing HCT 116 cells and stably P-gp-expressing Hep G2 cells were evaluated by performing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Among these products, several of them exhibited markedly higher potent cytotoxic effects not only on HCT116 cells but also Hep G2 cancer cells as compared to aloe-emodin.

Full text of DOI:10.1248/cpb.56.497

April 2008
Chem. Pharm. Bull. 56(4) 497—503 (2008)
497
Preparation of 1,8-Di-O-alkylaloe-emodins and 15-Amino-, 15-Thiocyano-,
and 15-Selenocyanochrysophanol Derivatives from Aloe-Emodin and
Studying Their Cytotoxic Effects
Xing-Ri CUI,a Kazutoshi TAKAHASHI,a Takeshi SHIMAMURA,a Jyunichi KOYANAGI,b Fusao KOMADA,c and
Setsuo SAITO*,a
a Faculty of Pharmaceutical Sciences, Josai University; 1–1 Keyakidai, Sakado, Saitama 350–0295, Japan: b Faculty of
Pharmaceutical Sciences, Josai International University; 1 Gumyo, Togane, Chiba 283–8555, Japan: and c Faculty of
Pharmaceutical Sciences, Himeji Dokkyo University; 7–2–1 Kami Ohno, Himeji, Hyogo 670–8524, Japan.
Received November 9, 2007; accepted February 6, 2008
1,8-Di-O-alkylaloe-emodin derivatives (namely, methyl-, propyl-, hexyl-, dodecyl-, and octadecyl) were syn-
thesized from naturally occurring aloe-emodin. Further, derivatives having various substituents such as diethyl-
amino, pyrrolidinyl, piperidinyl, methylpiperazinyl, imidazolyl, thiocyano and selenocyano groups at the 15 posi-
tion of chrysophanol and 1,8-di-O-hexylchrysophanol from aloe-emodin were synthesized. The cytotoxic effects
of these derivatives on less P-glycoprotein (P-gp)-expressing HCT 116 cells and stably P-gp-expressing Hep G2
cells were evaluated by performing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.
Among these products, several of them exhibited markedly higher potent cytotoxic effects not only on HCT116
cells but also Hep G2 cancer cells as compared to aloe-emodin.
Key words 1,8-di-O-alkylaloe-emodin; 15-aminochrysophanol; 15-thiocyanochrysophanol; 15-selenocyanochrysophanol; cyto-
toxic effect
Previously, we reported that when the cytotoxic effects of phenolic hydroxyl groups at the 1 and 8 positions and one
4ꢀ-O-alkylaloenin derivatives (from methyl to hexadecyl) de- aliphatic hydroxyl group at the 15 position. In this study, the
rived from aloenin (1) are compared, the longer the alkyl alkylations of the phenolic hydroxyl groups and the substitu-
chain of the 4ꢀ-O-alkylaloenin derivatives, the greater is the tion reactions with various amino groups and thiocyano and
enhancement in the cytotoxic effects on human colorectal selenocyano groups at the 15 position of 3 were performed to
(HCT 116) and human hepatoma (Hep G2) cancer cell compare their cytotoxic activities.
lines.1) Furthermore, we reported that pseudodiosgenone de-
First, several alkyl derivatives were prepared from 3. The
rivatives having various amino groups, thiocyano (SCN), and methylation of 3 with dimethylsulfate in the presence of
selenocyano (SeCN) groups at the 26 position derived from K2CO3 was done according to the method reported by Ross
diosgenin (2) exhibited the potent cytotoxic activities against and Mitali.13) to give 1,8-di-O-methylaloe-emodin 4 in a
the same cancer cell lines,2) while compounds 1 and 2 have 61.6% yield. Other alkylations were performed according to
not been known to exhibit cytotoxic activity yet. In our pre- the method of MacTough et al.14) Compound 3 was reacted
liminary investigation, these compounds also showed no with propyl iodide, hexyl bromide, dodecyl iodide, and oc-
marked cytotoxicity in less than 500 mM of the IC50 value— tadecyl iodide in the presence of K2CO3 to give 1,8-di-O-
the concentration at which 50% of the cells are inhibited propyl- 5, 1,8-di-O-hexyl- 6, 1,8-di-O-dodedcyl- 7, and 1,8-
from growing. However, from the both above-mentioned re- di-O-octadecylaloe-emodin 8 in 14.5, 49.0, 40.0 and 36.0%
ports, it is evident that a compound that possessed an alkyl
chain with an appropriate length or that introduced appropri-
ate substituents such as amino, thiocyano, and selecocyano
groups in the molecule seemed to exhibit potent cytotoxic
activity.
In the present study, we investigate the preparation of 1,8-
di-O-alkylaloe-emodins and 15-amino-, 15-thiocyano-, and
15-selenocyanochrysophanol derivatives from aloe-emodin
(3) which has been known to have several pharmacological
activities such as cytotoxic activity,3—5) antifungal activity,6)
antibacterial activity,7) and so on, and further we evaluate the
cytotoxic effects of the synthetic derivatives on HCT 116 and
Hep G2 cancer cell lines.
Results and Discussion
Aloe-emodin 3 is an anthraquinone derivative isolated
from many Chinese herbal medicines such as Aloe arboren-
sces MILL. var. natalensis BERGER (Liliaceae),8,9) Rheum
palumatum L. (Poligonaceae),10,11) Cassia tora L. (Legumi-
Fig. 1. Structures of Aloenin 1, 4ꢀ-O-Alkylaloenins, Diosgenin 2, Pseudo-
diosgenone Derivatives and Aloe-Emodin 3
nosae),12) and so on. This anthraquinone derivative has two
∗ To whom correspondence should be addressed. e-mail: saitoset@josai.ac.jp
© 2008 Pharmaceutical Society of Japan

498
Vol. 56, No. 4
Fig. 3. Structures of Compounds 9, 15, 16 and 24
Fig. 2. Structures of 1,8-Di-O-alkylaloe-emodins 4—8
Table 1. Comparison of Cytotoxic Effects of Various 1,8-O-Dialkylaloe-
emodin Derivatives 4—8 with Aloe-Emodin 3
IC50ꢂS.D. (mM)a)
Compound
HCT 116 cells
Hep G2 cells
3
4
5
6
7
8
8.7ꢂ0.8
40.8ꢂ5.7
46.9ꢂ4.3
9.7ꢂ3.5
10.0ꢂ0.9
ꢃ100b)
ꢃ100b)
ꢃ100b)
77.9ꢂ2.8c)
76.3ꢂ2.5c)
ꢃ100b,c)
ꢃ100b,c)
Fig. 4. Structures of Compounds 10—14 and 17—21
a) IC50 values (meanꢂS.D.) are the concentrations at which 50% of the cells are in-
hibited from growing. b) IC50 values more than 100 mM are indicated as ꢃ100. c)
Exact values of these compounds were not obtained because of the turbidity in the con-
centrations as indicated by the IC50 values.
yields, respectively.
The cytotoxic effects of alkylaloe-emodin derivatives were
tested by performing the 3-(4,5-dimethylthiazol-2-yl)-2,5-
diphenyltetrazolium bromide (MTT) assay15) using human
colorectal (HCT 116)16) and human hepatoma (Hep G2)17)
cancer cell lines, and the effects were represented by IC50
values—the concentrations at which 50% of the cells are in-
hibited from growing. The former expresses very little MDR
Fig. 5. Structures of Compounds 22, 23, 25 and 26
1 (P-glycoprotein; P-gp), while the latter overexpresses P- Hep G2 cells.
gp.17) It has been known that P-gp acts as an efflux pump to
Next, the hydroxyl group at the 15 position of aloe-emodin
remove several antitumor agents such as Ca2ꢁ antagonist, cy- 3 and 1,8-di-O-hexylaloe-emodin 6, which showed potent cy-
closporine, and dioxin from P-gp-overexpressing cells.18) totoxic activities against HCT 116 cells, was replaced with
Among alkylaloe-emodins 4—8, only 1,8-di-O-hexylaloe- amino groups and thiocyano (SCN) and selenocyano (SeCN)
emodisn 6 showed an almost similar effect (IC50 value: groups, and the cytotoxic activities of the products were fur-
9.7ꢂ3.5 mM) on HCT 116 cells as compared to that of aloe- ther evaluated. The treatment of 3 with CBr4 and PPh3 in
emodin 3 (IC50 value: 8.7ꢂ0.8 mM) (Table 1). The activities tetra hydro fran (THF) gave bromide 9 in 81.9% yields,
of 1,8-O-dimethyl- 4 and 1,8-O-dipropylaloe-emodin 5 (IC50 which was used as the starting material for the introduction
values: 40.8ꢂ5.7 and 46.9ꢂ4.3 mM, respectively), which had of various amino groups at the 15 position of 3. Compound 9
shorter alkyl chains than that of 6, decreased. These results was reacted with diethylamine, pyrrolidine, piperidine, 1-
suggest that there is no relationship between the cytotoxic ac- methylpiperazine and imidazole according to the method of
tivity and the alkyl chain lengths of alkylaloe-emodin deriva- Quan et al.19) to give compounds 10—14 (in 48.3, 58.0, 28.6,
tives against HCT 116 cells. Although it was difficult to de- 33.7, 19.3% yields, respectively). In the preparation of amino
termine the exact IC50 values for 1,8-di-O-dodecyl- 7 and derivatives from 1,8-di-O-hexylaloe-emodin 6, iodide 15 was
1,8-di-O-octadecylaloe-emodin 8 (because of the turbidity in used as the starting material in order to increase the yield.
the concentrations that were used to determine the IC50 Compound 15 was derived from 6 as follows: the tosyla-
value), they showed no marked activities. In the case of Hep tion20) of 6 gave tosylate 16 that reacted with sodium iodide
G2 cells, only 3 showed potent activity (IC50 value: to give 15. The reaction of 15 with diethylamine, pyrrolidine,
10.0ꢂ0.9 mM) which was almost similar to the value of 3 in piperidine, 1-methylpiperazine, and imidazole gave 17—21
the case of HCT 116 cells, while all alkylated aloe-emodins (in 58.0, 62.0, 52.0, 48.3, 66.5% yields, respectively).
4—8 showed no marked activity. This result indicates that
Next, the hydroxyl group at the 15 position of compounds
aloe-emodin derivatives introducing alkyl groups at the 1 and 3 and 6 was replaced with thiocyano (SCN) and selenocyano
8 positions may be influenced by the efflux pump of P-gp in (SeCN) groups. The reaction of bromide 9 with KSCN and

April 2008
499
Table 2. Cytotoxic Effects of 15-Aminochrysophanols 10—14 and 1,8-
Di-O-hexyl-15-aminochrysophanols 17—21
Table 3. Cytotoxic Effects of 22, 23, 25 and 26 on HCT 116 and Hep G2
Cells
IC50ꢂS.D. (mM)a)
IC50ꢂS.D. (mM)a)
Compound
Compound
HCT 116 cells
Hep G2 cells
HCT 116 cells
Hep G2 cells
10
11
12
13
14
17
18
19
20
21
1.9ꢂ0.2
3.6ꢂ0.6
3.7ꢂ0.9
2.5ꢂ0.1
2.5ꢂ0.3
3.0ꢂ0.6
10.2ꢂ0.9
9.2ꢂ0.4
2.4ꢂ0.2
5.3ꢂ0.6
2.1ꢂ0.5
3.5ꢂ0.7
4.4ꢂ0.6
2.3ꢂ0.4
2.0ꢂ0.2
5.3ꢂ0.7
28.3ꢂ3.6
33.1ꢂ3.6
2.2ꢂ0.3
8.4ꢂ0.9
22
23
25
26
2.8ꢂ0.5
3.0ꢂ0.6
1.9ꢂ0.3
0.2ꢂ0.08
22.5ꢂ3.1
5.9ꢂ0.9
7.6ꢂ0.8
0.7ꢂ0.1
a) IC50 values (meanꢂS.D.) are the concentrations at which 50% of the cancer cells
are inhibited from growing.
aloe-emodin 3 and 1,8-di-O-hexylaloe-emodin 6, respec-
tively, were also investigated (Table 3). All these derivatives
enhanced the cytotoxic effects on HCT 116 cells as well as
on Hep G2 cells more than 3 and 6. 15-Thiocyanochryso-
phanol 22 and 15-selenocyanochrysophanol 23 exhibited
a) IC50 values (meanꢂS.D.) are the concentrations at which 50% of the cells are in-
hibited from growing.
KSeCN gave 15-thiocyanochrysophanol 22 and 15-seleno- markedly potent effects (IC50 values: 2.8ꢂ0.5, 3.0ꢂ0.6 mM
cyanochrysophanol 23 in 53.5 and 65.1% yields, respec- on HCT 116 cells and 22.5ꢂ3.1, 5.9ꢂ0.9 mM on Hep G2
tively. Similarly, bromide 24 derived from 6 by bromination cells, respectively). 1,8-Di-O-hexyl-15-thiocyanochrysopha-
was treated with KSCN and KSeCN to give 1,8-di-O-hexyl- nol 25 and 1,8-di-O-hexyl-15-selenocyanochrysophanol 26
15-thiocyanochrysophanol 25 and 1,8-di-O-hexyl-15- se- had much more potent effects (IC50 values: 1.9ꢂ0.3, 0.2ꢂ
lenocyanochrysophanol 26 in 76.6 and 86.2% yields, respec- 0.08 mM on HCT 116 cells and 7.6ꢂ0.8, 0.7ꢂ0.1 mM on Hep
tively.
G2 cells, respectively) than 22 and 23, respectively. Thus,
Koyama et al.21) already reported the cytotoxic effects of the introduction of SCN and SeCN groups into the aloe-
15-aminochrysophanol derivatives 10, 11, 12 and 14 using emodin molecules enhanced the cytotoxic effect.
murine L1210 leukemic cells human acute promyelocytic
leukemia cells (HL-60). In this study, we investigated the cy- Conclusions
totoxic effects of 15-aminochrysophanol derivative 13 and
In this study, 1,8-di-O-alkylaloe-emodins (4—8), 15-
15-amino-1,8-di-O-hexylchrysophanol derivatives 17—21 aminochrysophanols (10—14), 15-amino-1,8-di-O-hexyl-
together with 10, 11, 12 and 14 against HCT 116 and Hep chrysophanols (17—21), 15-thiocyano- and 15-selenocyano-
G2 cells; the results are listed in Table 2. All 15- chrysophanols (22, 23, respectively), and 1,8-di-O-hexyl-
aminochrysophanol derivatives 10—14 exhibited higher cy- 15-thicyano- and 1,8-di-O-hexyl-15-thicyanochrysophanols
totoxic effects (IC50 values: 1.9ꢂ0.2 to 3.7ꢂ0.9 mM) than (25, 26, respectively) were prepared from naturally occurring
that of 3 (IC50 value: 8.7ꢂ0.8 mM) on HCT 116 cells. Further, aloe-emodin 3, and the cytotoxic effects of these compounds
these compounds showed higher effects (IC50 values: were evaluated using HCT 116 and Hep G2 cancer cell lines.
2.0ꢂ0.2 to 4.4ꢂ0.6 mM) than that of 3 (IC50 value:
In alkyl derivatives 4—8, only 1,8-di-O-hexylaloe-emodin
10.0ꢂ0.9 mM) on Hep G2 cells. Thus, the replacement of the 6 (IC50 value: 9.7ꢂ3.5 mM) showed a potent cytotoxic effect
hydroxyl group at the 15 position of 3 with amino groups en- on HCT 116 cells similar to that of 3 (IC50 value:
hanced the cytotoxic effect. In the case of 1,8-di-O-hexyl-15- 8.7ꢂ0.8 mM). The effects of 15-aminochrysophanol 10—14
aminochrysophanol derivatives 17—21, 15-diethylamino, 4- obtained by replacement of the hydroxyl group at the 15 po-
methylpiperazin-1-yl, and imidazol-1-yl derivatives (17, 20, sition of 3 with diethylamino, pyrrolidinyl, piperidinyl, 4-
21, respectively) enhanced the cytotoxic effects (IC50 value: methylpiperazinyl and imidazolyl, respectively, enhanced
2.4ꢂ0.2 to 5.3ꢂ0.6 mM) on HCT 116 cells, although the ef- about 4.6—2.4-fold on HCT 116 cells. The replacement of
fects of pyrrolidin-1-yl 18 (IC50 value: 10.2ꢂ0.9 mM) and the hydroxyl group at the 15 position of 6 with diethylamino,
piperidin-1-yl derivative 19 (IC50 value: 9.2ꢂ0.4 mM) on the 4-methylpiperazinyl, and imidazolyl groups enhanced the ef-
same cells were almost similar to that of 6 (IC50 value: fects on HCT 116 cells (IC50 values: 2.4ꢂ0.2 to 5.3ꢂ
9.7ꢂ3.5 mM). In the case of Hep G2 cells, compounds 17— 0.6 mM), although the replacement of that with pyrrolidinyl
21 showed considerably higher potent effects than 6 (IC50 and piperidinyl groups showed similar effects (IC50 values:
value: more than 100 mM); in particular, 17, 20, and 21 exhib- 10.2ꢂ0.9, 9.2ꢂ0.4 mM, respectively) to that of 3. Further-
ited marked potent effects (IC50 values: 5.3ꢂ0.7, 2.2ꢂ0.3, more, all amino derivatives 10—14 and 17—21 enhanced the
8.4ꢂ0.9 mM, respectively). In this case, the effects of 15- effects on stably P-gp-expressing Hep G2 cells.
(pyrrolidin-1-yl) 18 and 15-(piperidin-1-yl) derivative 19
The replacement of the hydroxyl group at the 15 position
were lower than those of 17, 20, and 21. This result suggests of 3 and 6 with SCN and SeCN groups also enhanced the cy-
that compounds 18 and 19 seem to be more sensitive to P-gp totoxic effects (Table 3). In the case of Hep G2 cells, seleno-
of Hep G2 cells than 17, 20, and 21.
The cytotoxic effects of 15-thiocyano- and 15-seleno- value: 0.7ꢂ0.1 mM) showed higher potent effect on stably P-
cyanchrysophanol derivatives, 22 and 23, and 1,8-di-O- gp-expressing Hep G2 cells than corresponding thiocyano
cyano derivatives 23 (IC50 value: 5.9ꢂ0.9 mM) and 26 (IC50
hexyl-15-thiocyano-
and
1,8-di-O-hexyl-15-selono- derivatives 22 (IC50 value: 22.5ꢂ3.1 mM) and 25 (IC50 value:
cyanochrysophanol derivatives, 25 and 26, derived from 7.6ꢂ0.8 mM), respectively.

500
Vol. 56, No. 4
4.10 and 4.06 (each 2H, t, Jꢅ6.7 Hz, 1- or 8-OCH2), 1.94 (4H, CH2ꢄ2),
1.13 and 1.11 (each 3H, t, Jꢅ7.3 Hz, CH3ꢄ2). 13C-NMR (CDCl3) d: 184.2
(C-9), 182.1 (C-10), 159.4 (C-8), 159.0 (C-1), 147.4 (C-3), 136.0 (C-14),
134.7 (C-11), 133.5 (C-6), 124.5 (C-13), 123.4 (C-12), 119.7 (C-7), 118.9
(C-5), 117.0 (C-4), 116.4 (C-2), 71.0 (OCH2ꢄ2), 64.4 (C-15), 22.5
(CH2ꢄ2), 14.1 (CH3ꢄ2).
1,8-Di-O-hexylaloe-emodin (6) The general alkylation of 3 (100 mg,
0.37 mmol) with hexyl bromide (310 mg, 1.9 mmol) gave 6 (79.6 mg,
49.0%) as yellow needles, mp 97—99 °C (after recrystallization from ace-
tone). FAB-MS: m/z 439 [MꢁH]ꢁ. HR-MS (FAB): m/z Calcd for C27H35O5
[MꢁH]ꢁ; 439.2484, Found; 439.2489. 1H-NMR (CDCl3) d: 7.75 (1H, dd,
In this study, we found that 15-aminochrysophanols 10—
14, 15-amino-1,8-di-O-hexylchrysophanols 17, 20, and 21,
15-selenocyanochrysophanol 23, 1,8-di-O-hexyl-15-thio-
cyanochrysophanol 25 and 1,8-di-O-hexyl-15-selenocyano-
chrysophanol 26 exhibited markedly potent cytotoxic effects
on stably P-gp-expressing Hep G2 cancer cells. Although the
exact structure–activity relationship for the affinity to en-
zymes, intracellular accumulation, and so on has not been re-
solved yet, these derivatives may help to overcome drug ex-
cretion from stably P-gp-expressing cancer cells caused by Jꢅ7.6, 0.9 Hz, H-5), 7.59 (1H, d, Jꢅ1.5 Hz, H-4), 7.56 (1H, t, Jꢅ7.6 Hz, H-
6), 7.26 (1H, d, Jꢅ1.5 Hz, H-2), 7.26 (1H, dd, Jꢅ7.6, 0.9 Hz, H-7), 4.73
multidrug resistance without any modulator.
(2H, s, 15-CH2O), 4.12 and 4.06 (each 2H, t, Jꢅ6.7 Hz, 1- or 8-OCH2), 1.90
Experimental
(4H, m, CH2ꢄ2), 1.55 (4H, m, CH2ꢄ2), 1.37 (8H, m, CH2ꢄ4), 0.92 (6H, m,
CH3ꢄ2). 13C-NMR (CDCl3) d: 184.0 (C-9), 182.0 (C-10), 159.2 (C-8),
158.8 (C-1), 147.6 (C-3), 134.6 (C-14), 134.4 (C-11), 133.4 (C-6), 124.2 (C-
13), 122.9 (C-12), 119.5 (C-7), 118.7 (C-5), 116.8 (C-4), 116.2 (C-2), 69.6
(OCH2ꢄ2), 64.2 (C-15), 31.4 (CH2ꢄ2), 29.0 (CH2), 28.9 (CH2), 25.5
(CH2ꢄ2), 22.5 (CH2ꢄ2), 13.9 (CH3ꢄ2).
General Methods Reagent-grade chemicals and solvents were obtained
from commercial suppliers. The melting points (mp) were determined using
a Yanagimoto micromelting point apparatus and were uncorrected. Kieselgel
60 F254 (E. Merck) was used in thin-layer chromatography (TLC). Spots
were detected by spraying plates with 1 : 9 Ce(SO4)2–10% H2SO4 reagent,
followed by heating the plates at 250 °C for 4—5 min. Preparative TLC was
performed using silica gel 60 F254 (Merck, 200ꢄ200ꢄ2 mm). Column chro-
matography was carried out using Kieselgel 60 (E. Merck), then the eluates
were monitored by TLC. An SSC-6300 HPLC instrument (Senshu Co., Ltd.)
was employed for analytical HPLC using column DOCOSIL (Senshu Co.,
Ltd.; 10ꢄ250 mm) attached to an SSC autoinjector 6310 and an SSC frac-
1,8-Di-O-dodecylaloe-emodin (7) The general alkylation of 3 (100 mg,
0.37 mmol) with dodecyl iodide (550 mg, 1.9 mmol) gave 7 (90.0 mg,
40.0%) as yellow needles, mp 110—112 °C (after recrystallization from ace-
tone). FAB-MS: m/z 607 [MꢁH]ꢁ. HR-MS (FAB): m/z Calcd for C39H59O5
[MꢁH]ꢁ; 607.4363, Found; 607.4362. 1H-NMR (CDCl3) d: 7.74 (1H, dd,
Jꢅ7.6, 0.9 Hz, H-5), 7.57 (1H, br s, H-4), 7.56 (1H, t, Jꢅ7.6 Hz, H-6), 7.26
(1H, dd, Jꢅ7.6, 0.9 Hz, H-7), 7.25 (1H, br s, H-2), 4.73 (2H, s, 15-CH2OH),
4.12 and 4.04 (each 2H, t, Jꢅ6.7 Hz, 1- or 8-OCH2), 1.90 (4H, m, CH2ꢄ2),
1.53 (4H, m, CH2ꢄ2), 1.26 (32H, CH2ꢄ16), 0.88 (6H, t, Jꢅ6.7 Hz,
CH3ꢄ2). 13C-NMR (CDCl3) d: 184.0 (C-9), 182.1 (C-10), 159.2 (C-8),
158.9 (C-1), 147.8 (C-3), 134.7 (C-14), 134.5 (C-11), 133.5 (C-6), 124.3 (C-
13), 123.0 (C-12), 119.6 (C-7), 118.9 (C-5), 117.0 (C-4), 116.3 (C-2), 69.8
(OCH2ꢄ2), 64.2 (C-15), 31.9 (CH2ꢄ2), 29.6 (CH2ꢄ4), 29.4 (CH2ꢄ2), 29.3
(CH2ꢄ4), 29.1 (CH2ꢄ2), 29.0 (CH2ꢄ2), 25.9 (CH2ꢄ2), 22.6 (CH2ꢄ2),
14.1 (CH3ꢄ2).
tion collector 6320 for preparative HPLC. H- and 13C-NMR spectroscopy
1
investigations were carried out at 500 and 125 MHz, respectively, and 1H–1H
1
and H–13C COSY and HMBC spectra were obtained using a JEOL JNM-
A500 FT-NMR spectrometer. Tetramethylsilane was used as an internal stan-
dard. The chemical shifts are given in ppm. The multiplicities of the 1H-
NMR signals are indicated as s (singlet), d (doublet), dd (doublet of dou-
blets), t (triplet), q (quartet), quin (quintet), and m (multiplet). Electron im-
pact mass spectrum (EI-MS) and fast-atom-bombardment mass spectrum
(FAB-MS) were recorded using a JEOL JMS-DX 300 mass spectrometer.
The high-resolution mass (HR-MS) spectra were recorded using JEOL JMS-
700.
1,8-Di-O-octadecylaloe-emodin (8) The general alkylation of
3
(100 mg, 0.37 mmol) with octadecyl iodide (700 mg, 1.8 mmol) gave 8
(103 mg, 36.0%) as yellow needles, mp 114—116 °C (after recrystallization
from acetone). FAB-MS: m/z 775 [MꢁH]ꢁ. HR-MS (FAB): m/z Calcd for
1,8-Di-O-methylaloe-emodin (4) A solution of 3 (100 mg, 0.37 mmol)
in dry acetone (10 ml) was added with dimethylsulfate (230 mg, 1.8 mmol)
and absolute K2CO3 (250 mg, 1.8 mmol), and then refluxed overnight. The
reaction mixture was added with more dimethylsulfate (230 mg, 1.8 mmol)
and absolute K2CO3 (250 mg, 1.8 mmol) and refluxed for 12 h. The mixture
was poured into ice-cold water (50 ml) and extracted with AcOEt
(50 mlꢄ3). The AcOEt extracts were successively washed with brine and
water, dried over absolute Na2SO4, and then filtered. The filtrate was evapo-
rated to give a residue that was subjected to column chromatography (a gra-
dient of 0—5% AcOEt in hexane), followed by preparative HPLC (solvent
system: 55% H2O in acetone, flow rate of 1.0 ml/min, and column tempera-
ture of 40 °C) to obtain 4 (68.2 mg, 61.6%) as yellow needles, mp 223—
226 °C (after recrystallization from acetone). FAB-MS: m/z 299 [MꢁH]ꢁ.
HR-MS (FAB): m/z Calcd for C17H15O5 [MꢁH]ꢁ; 299.0919, Found;
1
C51H83O5 [MꢁH]ꢁ; 775.6240, Found; 775.6224. H-NMR (CDCl3) d: 7.78
(1H, dd, Jꢅ7.6, 0.9 Hz, H-5), 7.67 (1H, br s, H-4), 7.58 (1H, t, Jꢅ7.6 Hz, H-
6), 7.31 (1H, br s, H-2), 7.26 (1H, dd, Jꢅ7.6, 0.9 Hz, H-7), 4.77 (2H, s, 15-
CH2OH), 4.12 and 4.11 (each 2H, t, Jꢅ6.4 Hz, 1- or 8-OCH2), 1.91 (4H, m,
CH2ꢄ2), 1.55 (4H, m,CH2ꢄ2), 1.25 (56H, m, CH2ꢄ28), 0.88 (6H, t,
Jꢅ7.0 Hz, CH3ꢄ2). 13C-NMR (CDCl3) d: 184.2 (C-9), 182.0 (C-10), 159.4
(C-8), 159.0 (C-1), 147.3 (C-3), 134.8 (C-14), 134.8 (C-11), 133.5 (C-6),
124.5 (C-13), 123.5 (C-12), 119.7 (C-7), 118.9 (C-5), 117.1 (C-4), 116.3 (C-
2), 69.9 (OCH2ꢄ2), 64.5 (C-15), 31.9 (CH2ꢄ2), 29.8 (CH2), 29.7 (CH2),
29.5 (CH2ꢄ4), 29.4 (CH2ꢄ10), 29.2 (CH2ꢄ8), 29.1 (CH2ꢄ2), 26.0
(CH2ꢄ2), 22.7 (CH2ꢄ2), 14.1 (CH3ꢄ2).
15-Bromochrysophanol (9) To a slolution of aloe-emodin 3 (500 mg,
1.85 mmol) in THF (100 ml), PPh3 (2.65 g, 10.1 mmol) and CBr4 (3.35 g,
10.1 mmol) were added and stirred at room temperature for 2 h. The reaction
mixture was filtered and the filtrate was evaporated to give a residue that was
subjected to column chromatography (toluene) to obtain compound 9
(505 mg, 81.9%) as a yellow solid (mp 221—223 °C). EI-MS: m/z 332 [M]ꢁ
and 334 [Mꢁ2]ꢁ. HR-MS (EI): m/z Calcd for C15H9BrO4 [M]ꢁ; 331.9684,
Found; 331.9691. 1H-NMR (CDCl3) d: 11.99 and 11.96 (each 1H, s, 1- or 8-
OH), 7.78 (1H, dd, Jꢅ7.3, 1.2 Hz, H-5), 7.78 (1H, d, Jꢅ1.5 Hz, H-4), 7.63
(1H, t, Jꢅ7.3 Hz, H-6), 7.26 (1H, d, Jꢅ1.5 Hz, H-2), 7.25 (1H, dd, Jꢅ7.3,
1.2 Hz, H-7), 4.41 (2H, s, 15-CH2Br).
1
299.0921. H-NMR (d6-DMSO) d: 7.74 (1H, t, Jꢅ8.2 Hz, H-6), 7.68 (1H,
dd, Jꢅ8.2, 0.9 Hz, H-5), 7.67 (1H, br s, H-4), 7.53 (1H, dd, Jꢅ8.2, 0.9 Hz,
H-7), 7.45 (1H, br s, H-2), 5.54 (1H, t, Jꢅ5.8 Hz, 15-CH2OH), 4.64 (2H, d,
Jꢅ5.8 Hz, 15-CH2OH), 3.92 (6H, s, 1-, 8-OCH3). 13C-NMR (CDCl3) d:
183.4 (C-9), 181.1 (C-10), 158.8 (C-8), 158.7 (C-1), 149.7 (C-3), 134.1 (C-
11), 134.1 (C-14), 133.9 (C-6), 123.5 (C-13), 122.0 (C-12), 118.9 (C-7),
118.1 (C-5), 115.9 (C-4), 115.5 (C-2), 62.3 (C-15), 56.3 (OCH3), 56.2
(OCH3).
1,8-Di-O-propylaloe-emodin (5) To
a
solution of
3
(100 mg,
0.37 mmol) in absolute DMF (10 ml), propyl iodide (460 mg, 2.7 mmol) and
absolute K2CO3 (260 mg, 1.9 mmol) were added, and then the mixture was
refluxed overnight. The reaction mixture was extracted with AcOEt
(50 mlꢄ3). The organic extracts were successively washed with 5% HCl,
10% NaHCO3 and water, dried over absolute MgSO4, and then filtered. The
filtrates were evaporated to give a residue that was subjected to column chro-
matography (a gradient of 0—5% AcOEt in hexane), followed by prepara-
tive HPLC (column: DOCOSIL 10ꢄ250 mm, solvent: 50% H2O in acetone,
flow rate: 1 ml/min, column temperature: 40 °C) to give 5 (19.0 mg, 14.5%)
as yellow needles, mp 126—128 °C (after recrystallization from methanol).
FAB-MS: m/z 355 [MꢁH]ꢁ. HR-MS (FAB): m/z Calcd for C21H23O5
[MꢁH]ꢁ; 355.1565, Found; 355.1545. 1H-NMR (CDCl3) d: 7.78 (1H, dd,
Jꢅ7.6, 0.9 Hz, H-5), 7.66 (1H, br s, H-4), 7.57 (1H, t, Jꢅ7.6 Hz, H-6), 7.30
(1H, br s, H-2), 7.27 (1H, dd, Jꢅ7.6, 0.9 Hz, H-7), 4.77 (2H, s, 15-CH2OH),
15-Diethylaminochrysophanol (10) To
a solution of 9 (100 mg,
0.3 mmol) in DMF (10 ml), diethylamine (250 ml, 2.4 mmol) was added and
stirred at room temperature for 12 h. The reaction mixture was poured into
ice-cold water (50 ml), and then extracted with AcOEt (50 mlꢄ3). The ex-
tracts were successively washed with 10% NaHCO3, and water, and then
dried over absolute MgSO4 and filtered. The filtrate was evaporated to give a
residue that was subjected to preparative TLC (5% MeOH in CH2Cl2) to ob-
tain compound 10 (46.9 mg, 48.3% yield, mp 97—99 °C after recrystalliza-
tion form acetone). EI-MS: m/z 325 [M]ꢁ. HR-MS (EI): m/z Calcd for
C19H19NO4 [M]ꢁ: 325.1313, Found; 325.1314. 1H-NMR (CDCl3) d: 12.10
(2H, 1-, 8-OH), 7.82 (1H, dd, Jꢅ7.6, 1.2 Hz, H-5), 7.81 (1H, d, Jꢅ0.9 Hz,
H-4), 7.77 (1H, t, Jꢅ7.6 Hz, H-6), 7.39 (1H, d, Jꢅ0.9 Hz, H-2), 7.28 (1H,
dd, Jꢅ7.6, 1.2 Hz, H-7), 3.68 (2H, s, 15-CH2), 2.60 (4H, q, Jꢅ7.0 Hz,

April 2008
501
NCH2CH3ꢄ2), 1.08 (6H, t, Jꢅ7.0 Hz, NCH2CH3ꢄ2). The 13C-NMR signals
are listed in Table 4.
CH3ꢄ2). 13C-NMR (CDCl3) d: 183.9 (C-9), 181.5 (C-10), 159.3 (C-8),
158.9 (C-1), 145.2 (C-3), 135.2 (C-14), 134.7 (C-11), 133.5 (C-6), 124.5 (C-
12), 123.9 (C-13), 119.6 (C-7), 119.3 (C-5), 118.8 (C-2), 118.6 (C-4), 69.9
and 69.8 (1-, 8-OCH2), 31.5 (CH2ꢄ2), 29.7 (C-15), 29.0 (CH2ꢄ2), 25.5
15-(Pyrrolidin-1-yl)chrysophanol (11) The general amination of 9
(100 mg, 0.3 mmol) with pyrrolidine (150 ml, 1.8 mmol) gave 11 (56.2 mg,
58.0%) as yellow needles, mp 123—125 °C (after recrystallization from ace- (CH2ꢄ2), 22.6 (CH2ꢄ2), 14.0 (CH3ꢄ2).
tone). FAB-MS: m/z 324 [MꢁH]ꢁ. HR-MS (FAB): m/z Calcd for
15-Diethylamino-1,8-di-O-hexylchrysophanol (17) To a solution of 15
C19H18NO4 [MꢁH]ꢁ; 324.1233, Found; 324.1236. 1H-NMR (CDCl3) d: (100 mg, 0.18 mmol) in DMF (10 ml), diethylamine (110 ml, 1.1 mmol) was
12.08 (2H, s, 1-, 8-OH), 7.81 (1H, dd, Jꢅ7.6, 0.9 Hz, H-5), 7.80 (1H, br s,
H-4), 7.77 (1H, t, Jꢅ7.6 Hz, H-6), 7.35 (1H, br s, H-2), 7.30 (1H, dd, Jꢅ7.9,
0.9 Hz, H-7), 3.75 (2H, s, 15-CH2), 2.60 (4H, m), and 1.84 (4H, m) (signals
on the pyrrolidinyl group). The 13C-NMR signals are listed in Table 4.
added and stirred at room temperature for 4 h. The reaction mixture was
poured into ice-cold water (50 ml), and then extracted with AcOEt
(30 mlꢄ3). The extracts were successively washed with 10% NaHCO3, and
water, and then dried over absolute MgSO4 and filtered. The filtrate was
evaporated to give a residue that was subjected to column chromatography
15-(Piperidin-1-yl)chrysophanol (12) The general amination of
9
(100 mg, 0.3 mmol) with piperidine (250 ml, 2.5 mmol) gave 12 (28.9 mg,
(a gradient of 0—3% MeOH in CHCl3) to obtain compound 17 (51.5 mg,
1
28.6%) as yellow needles, mp 129—131 °C (after recrystallization from ace- 58.0% yield) as a yellow paste-like solid. FAB-MS: m/z 494 [MꢁH]ꢁ. H-
tone). FAB-MS: m/z 338 [MꢁH]ꢁ. HR-MS (FAB): m/z Calcd for NMR (CDCl3) d: 7.72 (1H, dd, Jꢅ7.6, 0.9 Hz, H-5), 7.64 (1H, d, Jꢅ1.5 Hz,
C20H20O4N [MꢁH]ꢁ; 338.1404, Found; 338.1392. 1H-NMR (CDCl3) d: H-4), 7.49 (1H, t, Jꢅ7.6 Hz, H-6), 7.36 (1H, d, Jꢅ1.5 Hz, H-2), 7.18 (1H,
12.02 and 11.95 (each s, 1H, 1- or 8-OH), 7.74 (1H, dd, Jꢅ7.3, 1.2 Hz, H-5),
7.71 (1H, d, Jꢅ1.5 Hz, H-4), 7.59 (1H, t, Jꢅ7.3 Hz, H-6), 7.26 (1H, d,
Jꢅ1.5 Hz, H-2), 7.21 (1H, dd, Jꢅ7.3, 1.2 Hz, H-7), 3.47 (2H, s, 15-CH2),
dd, Jꢅ7.6, 0.9 Hz, H-7), 4.06 and 4.04 (each 2H, t, Jꢅ6.7 Hz, 1- or 8-
OCH2), 3.60 (2H, s, 15-CH2), 2.51 (4H, q, Jꢅ7.0 Hz, NCH2CH3ꢄ2), 1.83
(4H, m, CH2ꢄ2), 1.49 (4H, m, CH2ꢄ2), 1.30 (8H, m, CH2ꢄ4), 1.00 (6H, t,
2.35, 1.54 and 1.38 (CH2ꢄ2, CH2ꢄ2 and CH2, respectively, on the Jꢅ7.0 Hz, NCH2CH3ꢄ2), 0.84 (6H, m, CH2CH3ꢄ2). The 13C-NMR signals
piperidinyl group). The 13C-NMR signals are listed in Table 4.
are listed in Table 4.
15-(4-Methylpiperazin-1-yl)chrysophanol (13) The general amination
of 9 (100 mg, 0.3 mmol) with 1-methylpiperazine (230 ml, 2.1 mmol) gave
13 (35.6 mg, 33.7%) as yellow needles, mp 151—153 °C (after recrystalliza-
tion from acetone). FAB-MS: m/z 353 [MꢁH]ꢁ. HR-MS (FAB): m/z Calcd
1,8-Di-O-hexyl-15-(pyrrolidin-1-yl)chrysophanol (18) The general
amination of 15 (100 mg, 0.18 mmol) with pyrrolidine (92 ml, 1.1 mmol)
gave 18 (54.8 mg, 62.0%) as a yellow paste-like solid. FAB-MS: m/z 492
[MꢁH]ꢁ. 1H-NMR (CDCl3) d: 7.75 (1H, dd, Jꢅ7.6, 1.2 Hz, H-5), 7.67 (1H,
for C20H21N2O4 [MꢁH]ꢁ; 353.1517, Found; 353.1501. 1H-NMR (CDCl3) d: d, Jꢅ1.2 Hz, H-4), 7.54 (1H, t, Jꢅ7.6 Hz, H-6), 7.48 (1H, d, Jꢅ1.2 Hz, H-
12.03 (2H, s, 1-, 8-OH), 7.82 (1H, dd, Jꢅ7.3, 1.2 Hz, H-5), 7.80 (1H, d,
Jꢅ1.5 Hz, H-4), 7.67 (1H, t, Jꢅ7.3 Hz, H-6), 7.31 (1H, d, Jꢅ1.5 Hz, H-2),
2), 7.23 (1H, dd, Jꢅ7.6, 1.2 Hz, H-7), 4.10 and 4.08 (each 2H, t, Jꢅ6.7 Hz,
1- or 8-OCH2), 3.81 (2H, s, 15-CH2), 2.69 (4H, NCH2ꢄ2 on the pyrrolidinyl
7.29 (1H, dd, Jꢅ7.3, 1.2 Hz, H-7), 3.59 (2H, s, 15-CH2), 3.32 (8H, m, group), 1.87 (4H, CH2ꢄ2 on the pyrrolidinyl group), 1.85 (4H, m, CH2ꢄ2),
NCH2ꢄ4), 1.25 (3H, s, NCH3). The 13C-NMR signals are listed in Table 4.
1.51 (4H, m, CH2ꢄ2), 1.33 (8H, m, CH2ꢄ4), 0.88 (6H, m, CH3ꢄ2). The
15-(1H-Imidazol-1-yl)chrysophanol (14) The general amination of 9 13C-NMR signals are listed in Table 4.
(100 mg, 0.3 mmol) with imidazole (102 mg, 1.5 mmol) gave 14 (18.5 mg,
1,8-Di-O-hexyl-15-(piperidin-1-yl)chrysophanol (19) The general am-
19.3%) as yellow needles, mp 208—210 °C (after recrystallization from ace- ination of 15 (100 mg, 0.18 mmol) with piperidine (110 ml, 1.1 mmol) gave
tone). EI-MS: m/z 320 [M]ꢁ. HR-MS (EI): m/z Calcd for C18H12N2O4 [M]ꢁ; 19 (47.2 mg, 52.0%) as yellow paste-like solids. FAB-MS: m/z 506
1
320.0801, Found; 320.0797. H-NMR (CDCl3) d: 12.00 (2H, s, 1-, 8-OH),
7.83 (1H, dd, Jꢅ7.3, 0.9 Hz, H-5), 7.71 (1H, t, Jꢅ7.3 Hz, H-6), 7.64 (1H,
[MꢁH]ꢁ. 1H-NMR (CDCl3) d: 7.76 (1H, dd, Jꢅ7.6, 0.9 Hz, H-5), 7.67 (1H,
d, Jꢅ1.2 Hz, H-4), 7.56 (1H, t, Jꢅ7.6 Hz, H-6), 7.44 (1H, d, Jꢅ1.2 Hz, H-
br s, H-4), 7.32 (1H, dd, Jꢅ7.7, 0.9 Hz, H-7), 7.72, 7.69 and 7.54 (each 1H, 2), 7.24 (1H, dd, Jꢅ7.6, 0.9 Hz, H-7), 4.10 and 4.08 (each 2H, t, Jꢅ6.7 Hz,
proton on the imidazolyl group), 6.97 (1H, br s, H-2), 5.24 (2H, s, 15-CH2).
1- or 8-OCH2), 3.70 (2H, s, 15-CH2), 2.55 (4H, NCH2ꢄ2 on the piperidinyl
group), 1.81 (4H, m, CH2ꢄ2), 1.63 (4H, CH2ꢄ2 on the piperidinyl group),
1.53 (4H, m, CH2ꢄ2), 1.46 (2H, CH2 on the piperidinyl group), 1.34 (8H,
m, CH2ꢄ4), 0.89 (6H, m, CH3ꢄ2). The 13C-NMR signals are listed in Table
4.
The 13C-NMR signals are listed in Table 4.
1,8-Di-O-hexyl-15-O-tosylaloe-emodin (16) To
a solution of 6
(440 mg, 1.0 mmol) in ether (100 ml), tosylchloride (1.0 g, 5.3 mmol) and
KOH (1.27 g, 22.6 mmol) were added and stirred at room temperature for
1 h. The reaction mixture was poured into ice-cold water (100 ml) and ex-
1,8-Di-O-hexyl-15-(4-methylpiperazin-1-yl)chrysophanol (20) The
tracted with AcOEt (100 mlꢄ3). The extracts were successively washed with general amination of 15 (100 mg, 0.18 mmol) with 1-methylpiperazine
5% HCl, 10% NaHCO3, brine and water, and then dried over absolute (100 ml, 0.9 mmol) gave 20 (45.2 mg, 48.3%) as a yellow paste-like solid.
MgSO4 and filtered. The filtrate was evaporated to give a residue that was FAB-MS: m/z 521 [MꢁH]ꢁ. 1H-NMR (CDCl3) d: 7.77 (1H, d, Jꢅ7.6 Hz, H-
subjected to column chromatography (a gradient of 0—1% acetone in
toluene) to obtain compound 16 (316 mg, 53.3%). FAB-MS: m/z 593
[MꢁH]ꢁ. 1H-NMR (CDCl3) d: 7.77 and 7.29 (each 2H, d, Jꢅ8.5 Hz, C6H4),
7.74 (1H, dd, Jꢅ7.6, 0.9 Hz, H-5), 7.56 (1H, t, Jꢅ7.6 Hz, H-6), 7.54 (1H, d,
5), 7.71 (1H, br s, H-4), 7.55 (1H, t, Jꢅ7.6 Hz, H-6), 7.29 (1H, br s, H-2),
7.23 (1H, d, Jꢅ7.6 Hz, H-7), 4.10 and 4.09 (each 2H, t, Jꢅ6.7 Hz, 1- or 8-
OCH2), 3.55 (2H, s, 15-CH2), 2.48 (8H, m, CH2ꢄ4 on the piperazinyl
group), 2.28 (3H, NCH3 on the piperazinyl group), 1.88 (4H, CH2ꢄ2), 1.55
Jꢅ1.5 Hz, H-4), 7.25 (1H, dd, Jꢅ7.6, 0.9 Hz, H-7), 7.15 (1H, d, Jꢅ1.5 Hz, (4H, m, CH2ꢄ2), 1.35 (8H, m, CH2ꢄ4), 0.90 (6H, m, CH3ꢄ2). The 13C-
H-2), 5.09 (2H, s, 15-CH2O), 4.08 and 4.03 (each 2H, t, Jꢅ6.7 Hz, 1- or 8-
OCH2), 2.38 (3H, s, C6H4CH3), 1.84 (4H, m, CH2ꢄ2), 1.53 (4H, m,
NMR signals are listed in Table 4.
1,8-Di-O-hexyl-15-(1H-imidazol-1-yl)chrysophanol (21) The general
CH2ꢄ2), 1.35 (8H, m, CH2ꢄ4), 0.90 (6H, m, CH3ꢄ2). 13C-NMR (CDCl3) amination of 15 (100 mg, 0.18 mmol) with imidazole (61.2 mg, 0.9 mmol)
d: 183.7 (C-9), 181.5 (C-10), 159.2 (C-8), 158.9 (C-1), 145.2
(CH3C6H4SO2), 139.1 (C-3), 134.9 (C-14), 134.5 (C-11), 133.6 (C-6), 132.8
(CH3C6H4SO2), 129.9 and 127.9 (CH3C6H4SO2), 124.5 (C-12), 124.3 (C-
13), 119.6 (C-7), 118.7 (C-5), 118.1 (C-2), 117.7 (C-4), 70.5 (C-15), 69.9
gave 21 (58 mg, 66.5%) as yellow needles (mp 147—148 °C after recrystal-
lization from acetone). FAB-MS: m/z 489 [MꢁH]ꢁ. HR-MS (FAB): m/z
Calcd for C30H37N2O4 [MꢁH]ꢁ: 489.2771, Found; 489.2771. 1H-NMR
(CDCl3) d: 7.75 (1H, dd, Jꢅ7.6, 0.9 Hz, H-5), 7.61 (1H, d, Jꢅ1.5 Hz, H-4),
and 69.8 (1-, 8-OCH2), 31.5 (CH2ꢄ2), 29.0 (CH2ꢄ2), 25.5 (CH2ꢄ2), 22.5 7.57 (1H, s, a proton on the imidazolyl group), 7.56 (1H, t, Jꢅ7.6 Hz, H-6),
(CH2ꢄ2), 21.6 (CH3C6H4SO2), 14.0 (CH3ꢄ2).
7.25 (1H, dd, Jꢅ7.6, 0.9 Hz, H-7), 7.11 and 6.90 (each 1H, s, a proton on the
imidazolyl group), 6.84 (1H, d, Jꢅ1.5 Hz, H-2), 5.17 (2H, 15-CH2), 4.09
and 3.97 (each 2H, t, Jꢅ6.7 Hz, 1- or 8-OCH2), 1.85 (4H, m, CH2ꢄ2), 1.51
(4H, m, CH2ꢄ2), 1.33 (8H, m, CH2ꢄ4), 0.89 (6H, m, CH3ꢄ2). The 13C-
1,8-Di-O-hexyl-15-iodochrysophanol (15) To a solution of compound
16 (1.0 g, 1.7 mmol) in 3-pentanone (120 ml), NaI (500 mg, 3.4 mmol) was
added and stirred at room temperature for 1 h. The reaction mixture was
poured into ice-cold water (100 ml) and extracted with AcOEt (100 mlꢄ3). NMR signals are listed in Table 4.
The extracts were successively washed with 10% Na2S2O3, brine and water,
15-Thiocyanochrysophanol (22) A solution of bromide 9 (50 mg,
and then dried over absolute Na2SO4 and filtered. The filtrate was evaporated 0.15 mmol) in absolute DMF (10 ml) was added with KSCN (58 mg,
to give a residue that was subjected to column chromatography (toluene) to 0.6 mmol) and stirred at 65 °C for 1 h. The reaction mixture was poured into
obtain compound 15 (520 mg, 55.8%) as a yellow solid (mp 145—147 °C). ice-cold water (20 ml) and extracted with CH2Cl2 (20 mlꢄ3). The extracts
FAB-MS: m/z 549 [MꢁH]ꢁ. HR-MS (FAB): m/z Calcd for C27H34IO4
were washed successively with brine and water, and then dried over absolute
[MꢁH]ꢁ: 549.1509, Found; 549.1502. 1H-NMR (CDCl3) d: 7.77 (1H, dd, Na2SO4 and filtered. The filtrate was evaporated to give a residue that was
Jꢅ7.6, 0.9 Hz, H-5), 7.76 (1H, d, Jꢅ1.5 Hz, H-4), 7.56 (1H, t, Jꢅ7.6 Hz, H-
6), 7.25 (1H, dd, Jꢅ7.6, 0.9 Hz, H-7), 7.21 (1H, d, Jꢅ1.5 Hz, H-2), 4.44
subjected to column chromatography (a gradient of 0—2% AcOEt in
toluene) to obtain compound 22 (25 mg, 53.5%) as solid (mp 192—194 °C).
(2H, s, 15-CH2I), 4.11 and 4.09 (each 2H, t, Jꢅ6.7 Hz, 1- or 8-OCH2), 1.88 EI-MS: m/z 311 [M]ꢁ. HR-MS (FAB): m/z Calcd for C16H9NO4S [M]ꢁ:
1
(4H, m, CH2ꢄ2), 1.54 (4H, m, CH2ꢄ2), 1.35 (8H, m, CH2ꢄ4), 0.90 (6H, m, 311.0252, Found; 311.0262. H-NMR (CDCl3) d: 12.02 (1H, s, OH), 11.93

502
Vol. 56, No. 4
Table 4. 13C-NMR Spectral Data of Various 15-Aminoderivatives 10—14 and 17—21a)
10
11
12
13
14
17
18
19
20
21
C-1
C-2
C-3
C-4
C-5
C-6
C-7
C-8
162.5
114.7
151.4
115.9
120.0
133.4
120.5
162.8
192.6
181.9
133.7
124.6
124.0
137.0
57.3
47.2
11.8
47.2
11.8
—
—
—
162.4
114.7
150.3
115.9
120.0
133.5
120.5
162.9
192.6
181.8
133.7
124.6
124.0
137.1
60.0
54.2
23.6
23.6
54.2
—
—
—
161.4
113.6
149.4
114.9
118.9
132.2
119.7
161.7
191.6
180.9
132.7
123.5
123.1
136.0
62.1
53.6
24.9
23.1
24.9
53.6
—
—
162.5
114.7
150.0
115.8
120.0
133.4
120.6
162.8
192.6
181.9
133.7
124.6
124.0
137.1
62.2
53.1
55.0
—
55.0
53.1
45.9
—
162.7
115.6
167.7
115.7
120.3
132.5
120.3
163.1
192.5
181.3
133.4
125.0
124.9
137.5
68.2
158.8
118.8
134.9
118.7
119.5
133.3
119.6
159.2
184.5
180.2
134.9
124.7
123.4
134.5
57.4
46.9
11.6
46.9
—
—
—
69.8
158.8
118.8
133.4
118.7
119.6
129.4
119.8
159.3
184.3
181.9
134.7
124.6
123.7
134.6
59.7
53.9
23.4
23.3
11.6
—
—
69.9
158.9
119.4
135.0
118.7
119.6
133.4
119.8
159.2
184.4
181.9
134.8
124.6
123.8
134.5
62.4
54.0
25.0
23.7
25.0
54.0
—
69.9
158.8
119.0
145.0
118.7
119.5
133.3
119.5
159.1
184.4
181.9
134.8
124.6
123.5
134.6
62.4
53.0
55.0
—
55.0
53.0
45.9
69.8
158.9
117.1
142.0
117.0
118.8
133.6
119.7
159.7
183.8
181.4
135.2
124.3
124.2
134.5
50.4
C-9
C-10
C-11
C-12
C-13
C-14
C-15
C-2ꢀ
C-3ꢀ
C-4ꢀ
C-5ꢀ
C-6ꢀ
C-7ꢀ
OCH2
137.5
—
130.9
120.3
—
137.5
—
130.3
119.2
—
—
—
—
69.9
69.7
69.8
69.8
31.6
31.5
29.0ꢄ2
25.5ꢄ2
22.6
69.7
69.8
31.5ꢄ2
29.0
CH2
—
—
—
—
—
31.5ꢄ2b)
29.0ꢄ2
25.5
31.5ꢄ2
29.0ꢄ2
25.5ꢄ2
22.5ꢄ2
—
31.5ꢄ2
29.0ꢄ2
25.5ꢄ2
22.5ꢄ2
—
28.9
25.6
22.5ꢄ2
—
25.5ꢄ2
22.5ꢄ2
—
—
22.5
—
CH3
—
—
—
—
—
14.0ꢄ2
14.0ꢄ2
14.0ꢄ2
14.0ꢄ2
14.0ꢄ2
a) Spectra were obtained in CDCl3. b) 31.5ꢄ2: two carbon signals overlapped at d 31.5 and others in a similar manner.
(1H, s, OH), 7.79 (1H, dd, Jꢅ7.3, 1.2 Hz, H-5), 7.76 (1H, d, Jꢅ1.5 Hz, H-4),
7.65 (1H, t, Jꢅ7.3 Hz, H-6), 7.27 (1H, dd, Jꢅ7.3, 1.2 Hz, H-7), 7.25 (1H, d,
Jꢅ1.5 Hz, H-2), 4.11 (2H, 15-CH2).
15-Selenocyanochrysophanol (23) A solution of bromide 9 (50 mg,
0.15 mmol) in absolute DMF (10 ml) was added with KSeCN (87 mg,
poured into ice-cold water (20 ml) and extracted with CH2Cl2 (20 mlꢄ3).
The extracts were washed successively with brine and water, and then dried
over absolute Na2SO4 and filtered. The filtrate was evaporated to a residue
that was recrystallized from ethanol to give compound 25 (37 mg, 76.6%) as
yellow needles (mp 134—136 °C). FAB-MS: m/z 480 [MꢁH]ꢁ. HR-MS
0.6 mmol) and stirred at room temperature for 1 h. The reaction mixture was (FAB): m/z Calcd for C28H34NO4S [MꢁH]ꢁ: 480.2209, Found; 480.2213.
poured into ice-cold water (20 ml) and extracted with CH2Cl2 (20 mlꢄ3). 1H-NMR (CDCl3) d: 7.80 (1H, dd, Jꢅ7.6, 0.9 Hz, H-5), 7.78 (1H, d,
The extracts were washed successively with brine and water, and then dried Jꢅ1.5 Hz, H-4), 7.60 (1H, t, Jꢅ7.6 Hz, H-6), 7.29 (1H, dd, Jꢅ7.6, 0.9 Hz,
over absolute Na2SO4 and filtered. The filtrate was evaporated to give a H-7), 7.26 (1H, d, Jꢅ1.5 Hz, H-2), 4.19 (2H, 15-CH2), 4.16 and 4.13 (each
residue which was subjected to column chromatography (a gradient of 0— 2H, t, Jꢅ6.7 Hz, 1- or 8-OCH2), 1.92 (4H, m, CH2ꢄ2), 1.57 (4H, m,
2% AcOEt in toluene) to obtain compound 23 (35 mg, 65.1%) as a yellow CH2ꢄ2), 1.38 (8H, m, CH2ꢄ4), 0.93 (6H, m, CH3ꢄ2).
solid (mp 178—181 °C). EI-MS: m/z 358 [M]ꢁ. HR-MS (EI): m/z Calcd for
C16H9NO4Se [M]ꢁ: 358.9720, Found; 358.9697. 1H-NMR (CDCl3) d: 12.09 mide 24 (50 mg, 0.10 mmol) in absolute DMF (10 ml) was added with
(1H, s, OH), 12.02 (1H, s, OH ), 7.85 (1H, dd, Jꢅ7.3, 1.2 Hz, H-5), 7.82 KSeCN (58 mg, 0.40 mmol) and stirred at 65 °C for 1 h. The reaction mix-
(1H, d, Jꢅ1.5 Hz, H-4), 7.72 (1H, t, Jꢅ7.3 Hz, H-6), 7.33 (1H, dd, Jꢅ7.3, ture was poured into ice-cold water (20 ml) and extracted with CH2Cl2
1,8-Di-O-hexyl-15-selenocyanochrysophanol (26) A solution of bro-
1.2 Hz, H-7), 7.30 (1H, d, Jꢅ1.5 Hz, H-2), 4.28 (2H, 15-CH2).
15-Bromo-1,8-di-O-hexylchrysophanol (24) To slolution of
(20 mlꢄ3). The extracts were washed successively with brine and water,
dried over absolute Na2SO4, and then filtered. The filtrate was evaporated to
a
6
(900 mg, 2.05 mmol) in ether (100 ml), PPh3 (1.8 g, 6.8 mmol) and CBr4 a residue that was subjected to column chromatography (a gradient of 0—
(2.24 g, 6.8 mmol) were added and stirred at room temperature for 12 h. The
6% AcOEt in toluene) to obtain compound 26 (45 mg, 86.2%) as a yellow
reaction mixture was filtered. The filtrate was evaporated to give a residue powder (mp 130—133 °C). FAB-MS: m/z 528 [MꢁH]ꢁ. HR-MS (FAB): m/z
that was subjected to column chromatography (a gradient of 0—3% AcOEt Calcd for C28H34NO4Se [MꢁH]ꢁ: 528.1653, Found; 528.1656. 1H-NMR
in toluene) to obtain compound 24 (850 mg, 83.0%) as a yellow solid (mp (CDCl3) d: 7.79 (1H, dd, Jꢅ7.6, 0.9 Hz, H-5), 7.76 (1H, d, Jꢅ1.8 Hz, H-4),
129—131 °C). EI-MS: m/z 501 [M]ꢁ and 503 [Mꢁ2]ꢁ. HR-MS (EI): m/z
7.59 (1H, t, Jꢅ7.6 Hz, H-6), 7.28 (1H, dd, Jꢅ7.6, 0.9 Hz, H-7), 7.26 (1H, d,
Calcd for C27H33BrO4 [M]ꢁ; 501.1562, Found; 501.1618. 1H-NMR (CDCl3) Jꢅ1.8 Hz, H-2), 4.31 (2H, 15-CH2), 4.15 and 4.12 (each 2H, t, Jꢅ6.7 Hz, 1-
d: 7.80 (1H, br s, H-4), 7.79 (1H, dd, Jꢅ7.6, 0.9 Hz, H-5), 7.59 (1H, t,
Jꢅ7.6 Hz, H-6), 7.27 (1H, dd, Jꢅ7.6, 0.9 Hz, H-7), 7.28 (1H, br s, H-2),
4.50 (2H, s, 15-CH2Br), 4.14 and 4.12 (each 2H, d, Jꢅ6.7 Hz, 1- or 8-
or 8-OCH2), 1.91 (4H, m, CH2ꢄ2), 1.58 (4H, m, CH2ꢄ2), 1.37 (8H,
CH2ꢄ4), 0.92 (6H, m, CH3ꢄ2).
Cytotoxic Effects. Cell Lines and Culture The human colorectal carci-
OCH2), 1.91 (4H, m, CH2ꢄ2), 1.57 (4H, m, CH2ꢄ2), 1.38 (8H, m, CH2ꢄ4), noma cell line (HCT 116, ATCC No. CCL-247) and human hepatoma cell
0.93 (6H, m, CH3ꢄ2). 13C-NMR (CDCl3) d: 183.8 (C-9), 181.5 (C-10),
159.3 (C-8), 158.9 (C-1), 143.3 (C-3), 135.1 (C-14), 134.6 (C-11), 133.6 (C-
6), 124.4 (C-12), 124.2 (C-13), 119.6 (C-7), 119.5 (C-5), 118.9 (C-2), 118.8
line (Hep G2 No. RCB0459) were purchased from Dainippon Pharmaceuti-
cal Co., Ltd. (Osaka, Japan) and RIKEN Cell Bank (Tsukuba, Japan), re-
spectively. Dulbecco’s modified Eagle’s medium (DMEM), McCoy’s 5A
(C-4), 69.9 and 69.8 (1- and 8-O-CH2), 31.9 (C-15), 31.5 (CH2ꢄ2), 29.0 medium, fetal bovine serum (FBS) and penicillin–streptomycin mixture
(CH2ꢄ2), 25.5 (CH2ꢄ2), 22.5 (CH2ꢄ2), 14.0 (CH3ꢄ2).
(100 U/ml penicillin and 100 mg/ml streptomycin) were purchased from
Wako Pure Chemical Industries, Ltd. (Osaka, Japan), Sigma (MO, U.S.A.),
Biosource International (CA, U.S.A.) and Bio Whittaker (ND, U.S.A.), re-
spectively. The HCT 116 cells were maintained in McCoy’s 5A medium and
1,8-Di-O-hexy-15-thiocyanochrysophanol (25) A solution of bromide
24 (50 mg, 0.10 mmol) in absolute DMF (10 ml) was added with KSCN
(39 mg, 0.40 mmol) and stirred at 65 °C for 2 h. The reaction mixture was

April 2008
503
Hep G2 cells were cultured in DMEM. Each medium was supplemented
with 10% FBS and a penicillin–streptomycin mixture at 37 °C in a humidi-
fied atmosphere containing 5% CO2 in air.
248—259 (2007).
6) Agarwall S. K., Singh S. S., Verma S. S., Kumar S., J. Ethnopharma-
col., 72, 43—46 (2000).
7) Basu S., Ghosh A., Hazra B., Phytother. Res., 19, 888—894 (2005).
8) Hay J. E., Haynes L. J., J. Chem. Soc., 1956, 3141—3147 (1956).
9) Okumura N., Hine N., Harada S., Fujioka T., Mihashi K., Yagi A.,
Phytochemistry, 43, 495—498 (1996).
Assay Procedure Aliquots (200 ml) of 5ꢄ103 cells per ml of HCT 116
and Hep G2 cells were seeded in 96 well flat-bottomed plates (MicrotestTM
Tissue Culture Plate, 96 Well, Flat Bottom with Low Evaporation Ltd., Fal-
con, NJ, U.S.A.), and they were incubated in a medium containing 10% FBS
and a penicillin–streptomycin mixture at 37 °C in a humidified atmosphere
10) Shibata S., Takido M., Yakugaku Zasshi, 72, 1311—1314 (1952).
of 5% CO2 for 24 h. The test drugs were dissolved in dimethyl sulfoxide 11) Zhou X., Song B., Jin L., Hu D., Diao C., Xu Z., Zou Z., Yang S.,
(DMSO). The incubation medium was replaced with each test medium giv-
ing a final concentration of 0.1—500 mmol/l of test compounds and no drug
in 2 ml DMSO over 2 d. The ability of the drug to inhibit cellular growth was
Bioorg. Med. Chem. Lett., 16, 563—568 (2006).
12) Kim Y. M., Lee C. H., Kim H. G., Lee H. S., J. Agric. Food Chem., 52,
6096—6100 (2006).
determined by performing the MTT assay.15) The cytotoxic effects of the test 13) Ross K. T., Mitali G., J. Am. Chem. Soc., 107, 3879—3884 (1985).
drugs were determined as previously described.1) Each experiment was per- 14) MacTough S. C., DeDolms S. J., Kohl N. E., Lobell R. B., Robinson
formed in duplicate wells, and all the experiments involving a control
(DMSO only) and the drug treatments were performed separately three to
five times. The data represent meanꢂS.D. values.
R. G., Graham S. L., Bioorg. Med. Chem. Lett., 11, 1257—1260
(2001).
15) Mosmann T., J. Immunol. Methods, 139, 55—63 (1983).
16) Kanzaki A., Takebayashi Y., Ren X.-Q., Miyashita H., Moro S.,
Akiyama S., Pommier Y., Mol. Cancer Ther., 1, 1327—1334 (2002).
References
1) Jin G.-Z., Quan H.-J., Koyanagi J., Takeuchi K., Miura Y., Komada F., 17) Lee G., Piqette-Miller M., Can. J. Pharmacol., 79, 876—884 (2001).
Saito S., Cancer Lett., 218, 15—20 (2005).
2) Quan H.-J., Koyanagi J., Komada F., Saito S., Eur. J. Med. Chem., 40,
662—673 (2005).
18) Takara K., Sakaeda T., Tanigawara Y., Nishiguchi K., Ohmto N., Hori-
nouchi M., Komada F., Ohnishi N., Yokoyama T., Okumura K., Eur. J.
Pharm. Sci., 16, 159—165 (2002).
3) Van Gorkom B. A. P., Timmer-Bosscha H., De Johg S., Van der Kolk 19) Quan H.-J., Koyanagi J., Hagiwara K., Cui X.-R., Isshiki Y., Kondo S.,
D. M., Kleibeuker J. H., De Vries E. G. E., Br. J. Cancer, 86, 1494—
1500 (2002).
4) Lian L. H., Park E. J., Piao H. S., Zhao Y. Z., Sohn D. H., Basic Clin.
Pharmacol. Toxicol., 96, 495—502 (2005).
5) Harhaji L., Mijatovic S., Maksimovic-Ivanic D., Popadic D., Isakovic
A., Todorovic-Markovic B., Trajkovic V., Eur. J. Pharmacol., 30,
Komada F., Saito S., Chem. Pharm. Bull., 54, 72—79 (2006).
20) Koch J. K., Hammond G. S., J. Am. Chem. Soc., 75, 3443—3444
(1953).
21) Koyama M., Takahashi K., Chou T.-C., Darzynkiewicz Z., Kapuscin-
ski J., Kelly T. R., Watanabe K. A., J. Med. Chem., 32, 1594—1599
(1989).