Cytotoxic polyketides from a marine-derived fungus Aspergillus glaucus

Article abstract of DOI:10.1021/np800303t

Eight new aromatic polyketides (2, 4-6, 8, 14, 16, and 17) together with eight known analogues (3, 7, 9-13, and 15) were isolated from the marine-derived fungus Aspergillus glaucus. The structures and stereochemistry of the new compounds were elucidated by spectroscopic and chemical methods, and their cytotoxicities were evaluated against the HL-60 and A-549 cell lines.

Full text of DOI:10.1021/np800303t

J. Nat. Prod. 2008, 71, 1837–1842
1837
Cytotoxic Polyketides from a Marine-derived Fungus Aspergillus glaucus
Lin Du, Tianjiao Zhu, Hongbing Liu, Yuchun Fang, Weiming Zhu, and Qianqun Gu*
Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean UniVersity of China,
Qingdao 266003, People’s Republic of China
ReceiVed May 20, 2008
Eight new aromatic polyketides (2, 4-6, 8, 14, 16, and 17) together with eight known analogues (3, 7, 9-13, and 15)
were isolated from the marine-derived fungus Aspergillus glaucus. The structures and stereochemistry of the new
compounds were elucidated by spectroscopic and chemical methods, and their cytotoxicities were evaluated against the
HL-60 and A-549 cell lines.
Fungal polyketides constitute a large family of secondary
metabolites endowed with a high degree of structural diversity and
various biological activities.1 These compounds include toxins such
as aflatoxin B1 produced by Aspergillus species, psychoactive
compounds such as xenovulene, and pharmaceuticals such as the
cholesterol-lowering drug lovastatin.2 We have previously reported
aspergiolide A (1), a novel cytotoxic anthraquinone derivative with
a naphtho[1,2,3-de]chromene-2,7-dione skeleton, from cultures of
the marine-derived fungus Aspergillus glaucus.7 The A. glaucus
group is well known for producing aromatic polyketide mycotox-
ins,3 such as emodin, erythroglaucin, questin, physcion, physcion-
9-anthrone, catenarin, rubrocristin,4 physcion dianthranol, eryth-
roglaucin,5 kotanin, and desmethylkotanin.6 In an effort to obtain
more insight into the biosynthetic mechanisms and structure-activity
relationships in this family of metabolites, our search for aromatic
polyketides from this strain led to the discovery of eight new
aromatic polyketides [namely, a new aspergiolide A analogue,
aspergiolide B (2); three naphthyl ribofuranosides, isotorachrysone-
6-O-R-D-ribofuranoside (4), 8-methoxy-3-methyl-1-naphthalenol-
6-O-R-D-ribofuranoside (5), and 8-methoxy-1-naphthalenol-6-O-
R-D-ribofuranoside (6); two anthracene derivatives, isoasperflavin
(8) and (+)-variecolorquinones A (14); and two bianthrones, (trans)-
and (cis)-emodin-physcion bianthrone (16 and 17)] and eight known
analogues [isotorachrysone (3), asperflavin (7), emodin (9), physcion
(10), questin (11), catenarin (12), rubrocristin (13), and physcion
bianthrones (15)]. In this paper, we describe the isolation, structure,
stereochemistry, and cytotoxicity against the HL-60 and A-549 cell
lines of the new compounds.
Table 1. 1H and 13C NMR and HMBC Data for Compound 2a
HMBC
position
δH (J/Hz)
δC
(HfC)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
159.1, qC
131.7, qCb
132.5, qC
135.6, qCb
109.8, CH
163.4, qC
102.5, CH
164.1, qC
111.7, qC
184.6, qCc
109.2, qC
159.2, qC
122.0, CH
134.3, qC
141.6, qC
115.6, qC
15.8, CH3
191.2, qCc
115.4, qC
162.6, qC
100.7, CH
162.6, qC
111.8, CH
145.1, qC
23.1, CH3
56.1, CH3
7.00, s
6.75, s
3, 6, 7, 9
5, 6, 8, 9
7.20, s
2.45, s
11, 12, 15, 17
13, 14, 15
6.09, s
19, 20, 22, 23
19, 21, 22, 25
6.24, d (2.2)
25
2.54, s
3.88, s
11.16, s
13.84, s
10.50 br, s
10.35, s
19, 23, 24
8
5, 6, 7
11, 12, 13
8-OCH3
6-OH
12-OH
20-OH
22-OH
Results and Discussion
a Spectra were recorded in DMSO-d6 at 600 MHz for 1H NMR and
HMBC, and 150 MHz for 13C NMR using TMS as internal standard.
b,cSignals can be interchanged.
Compound 2 was a new analogue of aspergiolide A (1), and
both compounds had similar UV spectra [λmax (log ε) 202 (4.36),
233 (4.31), 308 (4.01), 434 (3.58) for 2; λmax (log ε) 203 (4.25),
235 (4.19), 307 (3.90), 431 (3.61) nm for 17]. The HRESIMS of 2
(m/z 473.0868 [M - H]-, calcd 473.0873) established the molecular
1
formula as C26H18O9. The H and 13C NMR data of 2 (Table 1)
were similar to those of 18 except that the signals of a phenolic
hydroxy group in the structure of 1 were replaced by those of a
methoxy group (δH 3.88, δC 56.1). The HMBC spectrum also
supported the existence of the naphtho[1,2,3-de]chromene-2,7-dione
skeleton (Figure 1), and the methoxy group was located at C-8 via
the correlation between the δH 3.88 and δC 164.1 resonances.
Therefore, compound 2 was identified as the 8-methoxy derivative
of 1 and was named aspergiolide B (2).
Compound 4 was obtained as yellow needles. Its molecular
formula C19H22O8 was determined by HRESIMS (m/z 377.1254
Figure 1. Selected HMBC correlations of compounds 2 and 4.
1
[M - H]-, calcd 377.1236). Comparison of the H and 13C NMR
data (Table 2) with those of isotorachrysone (3)9 suggested that
they had the same naphthalene skeleton (Figure 1). Further
comparison of their 1D NMR spectra indicated that compound 4
* To whom correspondence should be addressed. Tel: 0086-532-
82032065. Fax: 0086-532-82033054. E-mail: guqianq@ouc.edu.cn.
10.1021/np800303t CCC: $40.75
2008 American Chemical Society and American Society of Pharmacognosy
Published on Web 11/06/2008

1838 Journal of Natural Products, 2008, Vol. 71, No. 11
Table 2. 1H and 13C NMR Data for Compounds 3-6a
Du et al.
3b
4c
5c
6c
position
δH (J/Hz)
δC
δH (J/Hz)
δC
δH (J/Hz)
δC
δH (J/Hz)
δC
1
2
3
4
5
6
7
8
154.0, qC
122.9, qC
135.3, qC
119.0, CH
102.9, CH
159.0, qC
98.4, CH
157.8, qC
108.4, qC
138.8, qC
152.0, qC
122.7, qC
133.9, qC
118.8, CH
102.6, CH
156.6, qC
98.6, CH
157.3, qC
108.6, qC
136.8, qC
153.7, qC
110.1, CH
137.4, qC
117.2, CH
102.6, CH
155.4, qC
97.8, CH
156.9, qC
108.9, qC
137.0, qC
154.1, qC
6.47, s
6.62, dd (7.8, 0.9)
7.25, t (8.2, 7.8)
7.16 br, d (7.3)
6.96 d (2.2)
108.3, CH
127.9, CH
117.7, CH
103.0, CH
155.2, qC
98.6, CH
156.9, qC
110.7, qC
136.9, qC
6.89, s
6.66, d (2.2)
7.01, s
6.90, d (1.8)
6.95, s
6.86, d (1.8)
6.57, s
6.67, d (1.8)
6.58, d (1.8)
6.66, d (2.2)
9
10
6-OH
1-OH
1′
2′
3′
4′
1′′
2′′
3′′
8.84, s
9.75, s
9.73, s
9.12, s
2.31, s
3.97, s
9.22, s
3.99, s
204.0, qC
32.3, CH3
20.2, CH3
56.8, CH3
204.3, qC
32.1, CH3
19.6, CH3
56.4, CH3
100.2, CH
71.6, CH
69.4, CH
86.5, CH
61.6, CH2
2.49, s
2.24, s
4.11, s
2.52, s
2.22, s
4.01, s
5.73, d (4.8)
4.14, m
3.98, m
4.04, m
3.52, m
21.2, CH3
56.2, CH3
100.2, CH
71.5, CH
69.3, CH
86.3, CH
61.5, CH2
56.3, CH3
100.2, CH
71.5, CH
69.3, CH
86.4, CH
61.5, CH2
5.67, d (4.8)
4.09, m
3.94, m
3.99, m
3.48, m
5.70, d (4.8)
4.10, m
3.95, m
4.00, m
3.49, m
4′′
5′′
2′′-OH
3′′-OH
5′′-OH
a
4.75, d (8.7)
4.96, d (5.5)
4.86, t (5.5)
4.70, d (9.1)
4.93, d (5.5)
4.83, t (5.5)
4.70, d (9.1)
4.93, d (5.5)
4.83, t (5.5)
Spectra were recorded at 600 MHz for H NMR and 150 MHz for 13C NMR using TMS as internal standard. b Measured in acetone-d6. c Measured
1
in DMSO-d6.
was a furanoside. The connection between the sugar and naphtha-
Compounds 5 and 6 were both analogues of 4, and their
lene moieties through the O bond was established by the key HMBC
correlation from H-1′′ (δH 5.73) to C-6 (δC 156.6). The ribose
residue was confirmed through comparing the 13C NMR data with
those of several furanosides, such as methyl ribofuranosides10 and
asperflavin ribofuranoside.11 D-Ribose in 4 was established by
molecular formulas were established by HRESIMS as C17H20O7
and C16H18O7, respectively. Careful comparison of their H and
1
13C NMR spectra with those of 4 revealed that the structures
contained the same sugar residue and the only substituent differ-
ences appeared on the naphthalene moiety. The resonances of the
acetyl group in 4 were absent in 5, and a new meta-coupled aromatic
proton resonance (δ 6.47) appeared at this position. The corre-
sponding C-2 carbon shifted upfield from δ 122.7 to δ 110.1. In
compound 6, both the resonances of the acetyl group and CH3-3′
were absent and two ortho-coupled aromatic proton signals (δ 6.62
and 7.25) appeared correspondingly at C-2 (δ 108.3) and C-3 (δ
measurement of its optical rotation following acid hydrolysis ([R]20
D
-18.5, c 0.085, H2O).12 The sugar moiety was further determined
as R-D-ribofuranose by comparison of the J1′′,2′′ value (4.8 Hz) with
those of the methyl-R-D-ribofuranoside (J1,2 ) 4.3 Hz) and methyl-
ꢀ-D-ribofuranoside (J1,2 ) 1.2 Hz).13 Thus, compound 4 was
identified as isotorachrysone-6-O-R-D-ribofuranoside.

Cytotoxic Polyketides from Aspergillus glaucus
Journal of Natural Products, 2008, Vol. 71, No. 11 1839
Table 3. 1H and 13C NMR Data for Compounds 7 and 8a
7
8
position
δH (J/Hz)
δC
δH (J/Hz)
δC
1
2
203.2, qC
51.4, CH2
202.5, qC
43.0, CH2
2.82, d (16.9)
2.62, dd (16.9, 1.8)
2.72, dd (4.6, 17.4)
2.51, dd (10.5, 17.4)
2.07, m
3
4
69.4, qC
36.3, CH
2.96, d (16.0)
2.87, d (14.6)
6.54, d (2.2)
42.7, CH2
101.9, CH
160.4, qC
97.8, CH
161.2, qC
165.0, qC
115.7, CH
28.9, CH3
55.7, CH3
137.8, qC
108.9, qC
108.1, qC
141.6, qC
4.30 br, t (7.2, 7.7)
6.62, d (2.2)
71.9, CH
102.6, CH
160.6, qC
98.1, CH
161.2, qC
165.2, qC
113.8, CH
17.8, CH3
55.7, CH3
141.6, qC
108.3, qCb
108.0, qCb
142.2, qC
5
6
7
8
6.41, d (2.2)
6.45, d (1.8)
9
10
3-CH3
8-OCH3
4a
6.79, s
1.26, s
3.84, s
7.10, d (0.8)
1.05, d (6.4)
3.85, s
8a
9a
10a
3-OH
4-OH
6-OH
9-OH
4.83, s
5.53, d (6.9)
10.34, s
15.10 (s)
10.28, s
14.97, s
a Spectra were recorded in DMSO-d6 at 600 MHz for 1H NMR and 150 MHz for 13C NMR using TMS as internal standard. b Signals can be
interchanged.
127.9). Therefore, 5 and 6 were identified as 8-methoxy-3-methyl-
1-naphthalenol-6-O-R-D-ribofuranoside and 8-methoxy-1-naphtha-
lenol-6-O-R-D-ribofuranoside, respectively. To date, less than 10
naphthyl furanosides have been identified as natural products, and
only one naphthyl ribofuranoside has been reported previously.14,15
Compound 8 had the same molecular formula, C16H16O5,
established by the HRESIMS (m/z 287.0912 [M - H]-, calcd
287.0919), as the known pigment asperflavin (7).16,17 Careful
comparison of their 1D NMR data (Table 3) indicated that they
had the same skeleton and only OH-3 in 7 shifted to C-4 in 8. This
was confirmed by analyzing the peak shapes and J values of H-2
(δ 2.72, dd, J ) 4.6, 17.4; δ 2.51, dd, J ) 10.5, 17.4), H-3 (δ
2.07, m), and H-4 (δ 4.30, brt, J ) 7.2, 7.7). The J3,4 (7.7 Hz)
value helped to establish the trans configuration of C-3/C-4.18 The
absolute configuration was thus determined to be 3R, 4S by the
maximal negative Cotton effect at 281.0 nm and the maximal
positive effect at 223.4 nm in the CD spectrum.19 Therefore, the
structure of 8 was established, and the compound was named
isoasperflavin.
OH-8/8′ were more downfield in 16 than in 17. Comparison with
the literature data indicated that 16 and 17 respectively had a trans
and a cis relationship between H-10/H-10′.21,23,24
Aromatic polyketides differ from other polyketides by their
characteristic polycyclic aromatic structures.26 They are produced
by repetitive Claisen condensations of a starter unit (a dedicated
FAS, another PKS or an acyl CoA) with malonyl-CoA elongation
units. The biosynthesis of polyketides in fungi is governed by
iterative type I polyketide synthases (PKS), which are multifunc-
tional proteins consisting of domains for individual enzyme
activities.1,2,26 Aspergiolide B (2) may have a biosynthetic pathway
similar to aspergiolide A (1), probably using the same PKS but
with a different anthraquinone precursor, rubrocristin (13).7 Com-
pound 2 may also be formed through postmodification of compound
1, such as O-methylation by S-adenosylmethionine (Figure 2, A).
The biogenetic relationships of the other polyketides (3-17) isolated
herein are postulated (Figure 2, B). With the accumulation of
knowledge about the enzymology and the genome of A. glaucus,
investigation strategies employing precursor-directed biosynthesis27
and mutational biosynthesis28 become feasible for further studies
on aspergiolide polyketides.
The new compounds were evaluated for their cytotoxicities
against the HL-60 cell line by the MTT method29 and the A-549
cell line by the SRB method.30 Aspergiolide B (2) showed potent
cytotoxicities against the HL-60 and A-549 cell lines with IC50
values of 0.51 and 0.24 µM, respectively, indicating that the
O-methylation of OH-8 did not negatively impact its activities.7
Compound 16, (trans)-emodin-physcion bianthrone, showed moder-
ate cytotoxicities against the HL-60 and A-549 cell lines with IC50
values of 7.8 and 9.2 µM, respectively. Its cis-isomer, compound
17, showed comparable cytotoxicities, and the IC50 values were
44.0 and 14.2 µM, respectively. It appears that the isomerization
of the C-10/C-10′ axis does not impact the activities of the emodin-
physcion bianthrones. The other new compounds showed no
cytotoxicity at 100 µM against either cell line, suggesting that the
naphtho[1,2,3-de]chromene-2,7-dione skeleton may be important
for cytotoxicity and warrants further investigation to identify the
molecular targets for the aspergiolides.
Compound 14 was a yellow pigment with the molecular formula
C20H18O9 established by HRESIMS (m/z 403.1021 [M + H]+, calcd
403.1029). Both the UV spectra [λmax (log ε) 440 (3.45), 286 (3.88),
251 (3.75), 223 (4.05)] and the 1D NMR data (Table 4) were
consistent with those of the known compound variecolorquinone
A, which was isolated from the metabolites produced by the
halotolerant fungal strain Aspergillus Variecolor B-17.20 Beca-
use they had opposite specific rotations ([R]20 ) +16.8 for 14;
D
[R]20 ) -18.0 for variecolorquinone A20), the absolute configu-
D
ration of C-3′′ in 14 was deduced as R and 14 was named (+)-
variecolorquinone A.
The new bianthrone isomers (16 and17) had UV spectra (λmax
239, 278, and 360) characteristic of bianthrones.21 Their HRESIMS
(m/z 523.1409 and 523.1400 [M - H]-, calcd 523.1393) established
1
the same molecular formula of C31H24O8. According to their H
NMR spectra (Table 4), they both had eight meta-coupled aromatic
protons, two methyl groups, five phenolic hydroxy groups, and one
methoxy group. Comparison of their 1D NMR data (Table 4) with
those of the physcion bianthrones (15),22 emodin bianthrones,23,24
and the anthracene monomers physcion and emodin25 indicated they
were two C-10/C-10′ isomers of physcion-emodin bianthrones.
Experimental Section
1
Furthermore, in the H NMR spectra of 16 and 17, the chemical
General Experimental Procedures. Melting points were measured
shifts of OH-1/1′ were more upfield and the shifts of OH-6 and
using a Yanaco MP-500D micromelting point apparatus and were

1840 Journal of Natural Products, 2008, Vol. 71, No. 11
Du et al.

Cytotoxic Polyketides from Aspergillus glaucus
Journal of Natural Products, 2008, Vol. 71, No. 11 1841
Figure 2. Postulated biosynthetic pathways for aspergiolide B (2, A) and polyketides 3-17 (B).
uncorrected. Specific rotations were obtained on a Jasco P-1020 digital
polarimeter. UV spectra were recorded on Beckman DU 640 spectro-
photometer. IR spectra were taken on a Nicolet Nexus 470 spectro-
CHCl3/MeOH (40:1, 20:1, 10:1, and 9:1) were separately subjected to
repeated Sephadex LH-20 column chromatography (CHCl3/MeOH, 1:1).
The active subfractions 5-5-2, 6-2-2, 5-5-1-4, and 4-6-6-1 were further
purified respectively by HPLC using a reversed-phase C18 column (50%
MeOH, 30% CH3CN, 35% CH3CN, and 75% CH3CN, 4.0 mL/min),
to give compounds 4 (21.3 mg), 5 (2.8 mg), 6 (4.5 mg), 8 (3.0 mg), 16
(3.2 mg), and 17 (4.1 mg). Another two subfractions, 5-5-2-5 and 6-3-
4, were respectively subjected to repeated Sephadex LH-20 column
chromatography (MeOH) to give compounds 2 (10 mg) and 14 (24
mg).
Acid Hydrolysis of 4 and Determination of the Configuration of
the Ribofuranose. A solution of 4 (9 mg) in 6 mol/L HCl (1 mL) was
reacted for 3 h at 100 °C. The reaction mixture was extracted with
EtOAc repeatedly to remove the aglycone fraction, which was identical
to isotorachrysone (3).7 The H2O layer was then concentrated to furnish
the sugar residue (1.7 mg). The rotation recorded for the ribose isolated
in this study was [R]20D -18.5 (c 0.085, H2O), which closely matched
that for the D-ribose (lit. -20).9
Biological Assays. Cytotoxic activity was evaluated using the HL-
60 cell line by the MTT method29 and the A-549 cell line by the SRB
method.30 In the MTT assay, the cell line was grown in RPMI-1640
supplemented with 10% FBS under a humidified atmosphere of 5%
CO2 and 95% air at 37 °C. Cell suspensions (200 µL) at a density of
5 × 104 cells/mL were plated in 96-well microtiter plates and incubated
for 24 h. The test compound solutions (2 µL in MeOH) at different
concentrations were added to each well and further incubated for 72 h
under the same conditions. MTT solution (20 µL of a 5 mg/mL solution
in IPMI-1640 medium) was added to each well and incubated for 4 h.
Old medium (150 µL) containing MTT was then gently replaced by
1
photometer in KBr discs. H NMR, 13C NMR, and DEPT spectra and
2D-NMR were recorded on a JEOL JNM-ECP 600 spectrometer using
TMS as internal standard, and chemical shifts were recorded as δ values.
ESIMS were measured on a Q-TOF Ultima Global GAA076 LC mass
spectrometer. Semiprepartive HPLC was performed using an ODS
column [YMC-pak ODS-A, 10 × 250 mm, 5 µm, 4 mL/min].
Fungal Material. The fungus Aspergillus glaucus was obtained from
marine sediment surrounding mangrove roots collected in the Fujian
Province, China. It was identified by Prof. Li Tian, the First Institute
of Oceanography, SOA, Qingdao, China, and preserved in the China
Center for Type Culture Collection (patent depositary number CCTCC
M 206022). Working stocks were prepared on potato dextrose agar
slants stored at 4 °C.
Fermentation and Extraction. Spores were directly inoculated into
500 mL Erlenmeyer flasks containing 100 mL fermentation media
(mannitol 20 g, maltose 20 g, glucose 10 g, monosodium glutamate
10 g, KH2PO4 0.5 g, MgSO4 ·7H2O 0.3 g, yeast extract 3 g, and corn
steep liquor 1 g, dissolved in 1 L of seawater, pH 6.5). The flasks
were incubated on a rotatory shaker at 165 rpm at 28 °C. After 9 days
of cultivation, 15 L of whole broth was filtered through cheesecloth to
separate the broth supernatant and mycelia. The former was extracted
with EtOAc, while the latter was extracted with acetone. The acetone
extract was evaporated under reduced pressure to afford an aqueous
solution and then extracted with EtOAc. The two EtOAc extracts were
combined and concentrated in vacuo to give a crude gum (30 g).
Purification of the New Compounds. The crude gum (30 g) was
subjected to silica gel column chromatography (CHCl3/MeOH, v/v,
gradient), and the active fractions 3, 4, 5, and 6 eluted with the solvent

1842 Journal of Natural Products, 2008, Vol. 71, No. 11
Du et al.
DMSO and pipetted to dissolve any formazan crystals formed.
Absorbance was then determined on a Spectra Max Plus plate reader
at 540 nm.
Acknowledgment. This work was financially supported by the
Chinese National Science Fund (No. 30672527) and the Shandong
Provincial Natural Science Fund (No. Z2006C13). The antitumor assays
were performed at the Shanghai Institute of Materia Medica, Chinese
Academy of Sciences.
In the SRB assay, cell suspensions (200 µL) were plated in 96-cell
plates at a density of 2 × 105 cells/mL. Then the test compound
solutions (2 µL in MeOH) at different concentrations were added to
each well and further incubated for 24 h. Following drug exposure,
the cells were fixed with 12% trichloroacetic acid and the cell layer
was stained with 0.4% SRB. The absorbance of SRB solution was
measured at 515 nm. Dose-response curves were generated, and the
IC50 values were calculated from the linear portion of log dose response
curves.
References and Notes
(1) Julia, S.; Christian, H. J. Biotechnol. 2006, 124, 690–703.
(2) Cox, R. J. Org. Biomol. Chem. 2007, 5, 2010–2026.
(3) Ashley, J. N.; Raistrick, H.; Richards, T. Biochem. J. 1939, 33, 1291–
1303.
(4) Heidrun, A.; Ilham, K.; Hans, Z.; Hartmut, L. Arch. Microbiol. 1980,
126, 223–230.
(5) Bachmann, M.; Luthy, J.; Schlatter, C. J. Agric. Food Chem. 1979,
27, 1342–1347.
(6) George, B.; Dieter, H. K.; Shank, R. C.; Steven, M. W.; Wogan, G. N.
J. Org. Chem. 1971, 36, 1143–1147.
(7) Du, L.; Zhu, T.; Fang, Y.; Liu, H.; Gu, Q.; Zhu, W. Tetrahedron 2007,
63, 1085–1088.
(8) Du, L.; Zhu, T.; Fang, Y.; Liu, H.; Gu, Q.; Zhu, W. Tetrahedron 2008,
64, 4657.
(9) Lin, C. N.; Lu, C. M.; Lin, H. C.; Ko, F. N.; Teng, C. M. J. Nat.
Prod. 1995, 58, 1934–1940.
(10) Thomas, E. W.; Harry, P. C. H.; Terry, E. N.; Nick, A. M. Biochemistry
1974, 13, 2650–2655.
(11) Li, Y.; Li, X.; Lee, U.; Kang, J. S.; Choi, H. D.; Sona, B. W. Chem.
Pharm. Bull. 2006, 54, 882–883.
(12) Robert, K. N.; Harry, W. D.; Hewitt, G. F., Jr. J. Am. Chem. Soc.
1954, 76, 763–767.
(13) Anthony, S. S.; Robert, B. J. Org. Chem. 1984, 49, 3292–3300.
(14) Antkowiak, W. Z.; Krzyzosiak, W. J.; Biernat, J.; Ciesiolka, J.;
Gornicki, P. Bull. Acad. Pol. Sci., Ser. Sci. Chim. 1977, 25, 173–178.
(15) Antkowiak, W. Z.; Krzyzosiak, W. J. Bull. Acad. Pol. Sci., Ser. Sci.
Chim. 1977, 25, 421–425.
(16) Fujimoto, H.; Fujimaki, T.; Okuyama, E.; Yamazaki, M. Chem. Pharm.
Bull. 1999, 47, 1426–1432.
(17) John, F. G. J. Chem. Soc., Perkin Trans. 1 1972, 2406–2411.
(18) Bringmann, G.; Mu¨nchbach, M.; Messer, K.; Koppler, D.; Michel,
M.; Schupp, O.; Wenzel, M.; Louis, A. M. Phytochemistry 1999, 51,
693–699.
(19) Bringmann, G.; Messer, K.; Saeb, W.; Peters, E. M.; Peters, K.
Phytochemistry 2001, 56, 387–391.
Aspergiolide B (2): red solid (MeOH); UV (MeOH) λmax (log ε)
202 (4.36), 233 (4.31), 308 (4.01), 434 (3.58); IR (KBr) νmax cm-1
3133, 2925, 1678, 1588, 1439, 1377, 1337, 1236, 1204, 1173, 1083
1
cm-1; H and 13C NMR, see Table 1; HRESIMS m/z 473.0868 [M -
H]- (calcd for C26H17O9, 473.0873).
Isotorachrysone-6-O-r-D-ribofuranoside (4): yellow needles
(MeOH); mp 174-176 °C; [R]20 +178.6 (c 0.11, MeOH); UV
D
(MeOH) λmax (log ε) 245 (3.41), 308 (3.33), 337 (3.29); IR (KBr) νmax
3390, 3289, 2966, 2924, 2850, 1642, 1619, 1576, 1456, 1394, 1258,
1157, 1106, 1017, 803 cm-1; 1H and 13C NMR, see Table 2; HRESIMS
m/z 377.1254 [M - H]- (calcd for C19H21O8, 377.1236).
8-Methoxy-3-methyl-1-naphthalenol-6-O-r-D-ribofuranoside (5):
yellow needles (MeOH); mp 176-178 °C; [R]20 +110.7 (c 0.09,
D
MeOH); UV (MeOH) λmax (log ε) 237 (4.00), 303 (3.43), 318 (3.36),
333 (3.35); IR (KBr) νmax 3409, 2962, 2927, 2853, 1638, 1614, 1583,
1455, 1385, 1362, 1253, 1164, 1102, 1012, 849 cm-1; 1H and 13C NMR,
see Table 2; HRESIMS m/z 359.1118 [M + Na]+ (calcd for
C17H20O7Na, 359.1107).
8-Methoxy-1-naphthalenol-6-O-r-D-ribofuranoside (6): yellow oil
(MeOH); [R]20 +137.7 (c 0.15, MeOH); UV (MeOH) λmax (log ε)
D
244 (3.81), 299 (3.63), 321 (3.51), 335 (3.52); IR (KBr) νmax 3402,
2926, 1633, 1618, 1591, 1454, 1402, 1376, 1317, 1252, 1166, 1124,
1042, 1003 cm-1 1H and 13C NMR, see Table 2; HRESIMS m/z
;
345.0943 [M + Na]+ (calcd for C16H18O7Na, 345.0950).
Isoasperflavin (8): yellow solid (MeOH); [R]20 +34.1 (c 0.075,
D
MeOH); CD (MeOH) λmax (∆ε) 223.4 (0.9), 281.0 (-0.5); UV (MeOH)
λ
max (log ε) 233 (3.94), 268 (3.06), 318 (3.33), 331 (3.27), 392 (3.62);
IR (KBr) νmax 3367, 2923, 2853, 1681, 1595, 1368, 1260, 1202, 1091,
(20) Wang, W.; Zhu, T.; Tao, H.; Lu, Z.; Fang, Y.; Gu, Q.; Zhu, W. J.
Antibiot. 2007, 60, 603–607.
1045 cm-1; H and 13C NMR, see Table 3; HRESIMS m/z 287.0912
1
[M - H]- (calcd for C16H15O5, 287.0919).
(21) Politi, M.; Sanogo, R.; Ndjoko, K.; Guilet, D.; Wolfender, J. L.;
Hostettmann, K.; Morelli, I. Phytochem. Anal. 2004, 15, 355–364.
(22) Monache, G. D.; Rosa, M. C.; Scurria, R.; Monacelli, B.; Pasqua, G.;
Olio, G. D.; Botta, B. Phytochemistry 1991, 30, 1849–1854.
(23) Mai, L. P.; Gueritte, F.; Dumontet, V.; Tri, M. V.; Hill, B.; Thoison,
O.; Guenard, D.; Sevenet, T. J. Nat. Prod. 2001, 64, 1162–1168.
(24) Donald, W. C.; John, S. E.; Warwick, D. R. Aust. J. Chem. 1976, 29,
1535–1548.
(25) Danielsen, K.; Aksnes, D. W. Magn. Reson. Chem. 1992, 30, 359–
360.
(26) Shen, B. Top. Curr. Chem. 2000, 209, 1–51.
(27) Thiericke, R.; Rohr, J. Nat. Prod. Rep. 1993, 10, 265–289.
(28) Weist, S.; Su¨ssmuth, R. D. Appl. Microbiol. Biotechnol. 2005, 68,
141–150.
(+)-Variecolorquinones A (14): yellow solid (MeOH); [R]25D +16.8
(c 0.03, MeOH); UV (CHCl3) λmax (log ε) 440 (3.45), 286 (3.88), 251
(3.75), 223(4.05); IR (KBr) νmax 3425, 1718, 1672, 1635, 1598, 1574
cm-1; H and 13C NMR, see Table 4; HRESIMS m/z 403.1021 [M +
1
H]+ (calcd for C20H19O9, 403.1029).
(trans)-Emodin-physcion bianthrone (16): yellow solid (MeOH);
[R]20D -8.4 (c 0.10, CHCl3); UV (CHCl3) λmax (log ε) 239 (4.20), 278
(4.14), 360 (4.23); IR (KBr) νmax 3354, 2971, 2926, 2854, 1638, 1619,
1
1595, 1486, 1456, 1362, 1327, 1277, 1259, 1164, 1066 cm-1; H and
13C NMR, see Table 4; HRESIMS m/z 523.1409 [M - H]- (calcd for
C31H23O8, 523.1393).
(cis)-Emodin-physcion bianthrone (17): yellow solid (MeOH);
[R]20D +9.8 (c 0.06, CHCl3); UV (CHCl3) λmax (log ε) 239 (4.07), 278
(3.98), 360 (4.03);1H and 13C NMR, see Table 4; IR (KBr) νmax 3353,
2980, 2924, 2853, 1637, 1618, 1595, 1487, 1457, 1361, 1329, 1259,
1189, 1160, 1065 cm-1; HRESIMS m/z 523.1400 [M - H]- (calcd for
C31H23O8, 523.1393).
(29) Mosmann, T. J. Immunol. Methods 1983, 65, 55–63.
(30) Skehan, P.; Storeng, R.; Scudiero, D.; Monks, A.; McMahon, J.;
Vistica, D.; Warren, J. T.; Bokesch, H.; Kenney, S.; Boyd, M. R.
J. Natl. Cancer Inst. 1990, 82, 1107–1112.
NP800303T