Brevianamide J, A new indole alkaloid dimer from fungus Aspergillus versicolor

Article abstract of DOI:10.1021/ol901304y

Image Presented Brevianamide J (1), a new indole alkaloid dimer, was isolated together with four new diketopiperazine alkaloids (brevianamide K-N, 2-5) from the solid-state fermented culture of Aspergillus versicolor. Their structures were elucidated on the basis of spectral data. X-ray crystallographic analysis confirmed the structures of 1 and 4.

Full text of DOI:10.1021/ol901304y

ORGANIC
LETTERS
2
009
Vol. 11, No. 16
714-3717
Brevianamide J, A New Indole Alkaloid
Dimer from Fungus Aspergillus
versicolor
3
Guo-You Li, Tao Yang, Ying-Gang Luo, Xiao-Zhen Chen, Dong-Mei Fang, and
Guo-Lin Zhang*
Chengdu Institute of Biology, Chinese Academy of Sciences,
Chengdu 610041, People’s Republic of China
zhanggl@cib.ac.cn
Received June 11, 2009
ABSTRACT
Brevianamide J (1), a new indole alkaloid dimer, was isolated together with four new diketopiperazine alkaloids (brevianamide K-N, 2-5)
from the solid-state fermented culture of Aspergillus versicolor. Their structures were elucidated on the basis of spectral data. X-ray
crystallographic analysis confirmed the structures of 1 and 4.
5
6
Diketopiperazine alkaloids, a class of important secondary
ties, which attracted much attention of synthetic chemists.
1
metabolites, are widely found in fungi such as Aspergillus,
Species of Aspergillus are important medically and com-
mercially. Members of the genus are sources of natural
products that can be potentially used to treat human diseases.
In the course to investigate the alkaloids from the fungus
2
3
4
Penicillium, Pestalotiopsis, and Chromocleista. This class
of alkaloids are derived from different amino acids and one
or more isoprene units. Most of them are characteristic of
diverse ring systems and possess diverse biological activi-
7
Aspergillus Versicolor, a new alkaloid dimer (1), together
(
5) (a) Shinohara, C.; Hasumi, K.; Takei, Y.; Endo, A. J. Antibiot. 1994,
(
1) (a) Kato, H.; Yoshida, T.; Tokue, T.; Nojiri, Y.; Hirota, H.; Ohta,
T.; Williams, R. M.; Tsukamoto, S. Angew. Chem., Int. Ed. 2007, 46, 2254.
b) Tsukamoto, S.; Kato, H.; Greshock, T. J.; Hirota, H.; Ohta, T.; Williams,
47, 163. (b) Nuber, B.; Hansske, F.; Shinohara, C.; Miura, S.; Hasumi, K.;
Endo, A. J. Antibiot. 1994, 47, 168. (c) Fukuyama, T. F.; Chen, X.; Peng,
G. J. Am. Chem. Soc. 1994, 116, 3127. (d) Schkeryantz, J. M.; Woo, J. C. G.;
Danishefsky, S. J. J. Am. Chem. Soc. 1995, 117, 7025. (e) Wulff, J. E.;
Herzon, S. B.; Siegrist, R.; Myers, A. G. J. Am. Chem. Soc. 2007, 129,
4898.
(
R. M. J. Am. Chem. Soc. 2009, 131, 3834. (c) Wang, F. Z.; Fang, Y. C.;
Zhu, T. J.; Zhang, M.; Lin, A. Q.; Gu, Q. Q.; Zhu, W. M Tetrahedron
2
008, 64, 7986.
(
2) (a) Capon, R. J.; Stewart, M.; Ratnayake, R.; Lacey, E.; Gill, J. H.
(6) (a) Depew, K. M.; Danishefsky, S. J.; Rosen, N.; Sepp-Lorenzino,
L. J. Am. Chem. Soc. 1996, 118, 12463. (b) Schkeryantz, J. M.; Woo,
J. C. G.; Siliphaivanh, P.; Depew, K. M.; Danishefsky, S. J. J. Am. Chem.
Soc. 1999, 121, 11964. (c) Stocking, E. M.; Williams, Robert, M.; Sanz-
Cervera, J. F J. Am. Chem. Soc. 2000, 122, 9089. (d) Herzon, S. B.; Myers,
A. G. J. Am. Chem. Soc. 2005, 127, 5342. (e) Artman, G. D.; Grubbs, A. W.;
Williams, R. M. J. Am. Chem. Soc. 2007, 129, 6336.
J. Nat. Prod. 2007, 70, 1746. (b) Ding, Y. S.; Gruschow, S.; Greshock,
T. J.; Finefield, J. M.; Sherman, D. H.; Williams, R. M. J. Nat. Prod. 2008,
7
1, 1574. (c) Kozlovsky, A. G.; Vinokurova, N. G.; Adanin, V. M.;
Burkhardt, G.; Dahse, H.-M.; Grfe, U. J. Nat. Prod. 2000, 63, 698.
3) Ding, G.; Jiang, L. H.; Guo, L. D.; Chen, X. L.; Zhang, H.; Che,
Y. S. J. Nat. Prod. 2008, 71, 1861.
4) Park, Y. C.; Gunasekera, S. P.; Lopez, J. V.; McCarthy, P. J.; Wright,
A. E. J. Nat. Prod. 2006, 69, 580.
(
(
(7) Fenical, W.; Jensen, P. R.; Cheng, X. C. Avrainvillamide, a Cytotoxic
Marine Natural Product, and Derivatives there of U.S. Patent 6066635, 2000.
1
0.1021/ol901304y CCC: $40.75  2009 American Chemical Society
Published on Web 07/23/2009

with four new diketopiperazine alkaloids (2-5), was isolated
from the solid-state fermented culture of Aspergillus Versi-
color. Compound 1 was a new alkaloid dimer. It may be
derived from the corresponding monomer (2). Compound 1
represented a unique structure of indole alkaloid. Compound
Table 1. NMR Data of 1 and 2 ( H: 600 MHz; 13C: 150
MHz)
1
, ,
a b c
1
2
3
is the first type of oxepin-containing alkaloid with
no.
1
2
3
4
6
δH(mult., J Hz)
δC
δH(mult., J Hz)
δC
phenylalanine residue. Here, the isolation, structure elucida-
tion, and biological activities of compounds 1-5 are
described (Figure 1).
163.4
154.4
11.29 (s)
8.77 (1H, s)
127.1
161.4
126.3
155.1
46.0
4.17 (dd, 9.0, 8.8)
45.0 4.00 (2H, t, 8.9)
4
.02 (t, 9.0)
2.29 (1H, m)
.15 (1H, m)
7
29.3 2.75 (2H, td, 8.9, 2.9)
28.1
2
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
3.65 (1H, d, 10.2)
52.6 6.09 (1H, d, 2.9)
102.2
115.0 6.89 (1H, s)
105.3
127.5
121.0 7.41 (1H, d, 7.9)
120.4 7.00 (1H, t, 7.9)
122.9 7.06 (1H, t, 7.9)
111.0 7.17 (1H, d, 7.9)
135.8
11.06 (1H, s)
144.4
119.2
134.2
110.3
103.7
126.4
119.2
119.4
121.3
112.1
135.6
0
1
2
3
4
5
6
7
8
9
0
1
2
7.80 (1H, s)
8.02 (1H, d, 8.0)
7.52 (1H, t, 8.0)
6.96 (1H, t, 8.0)
7.03 (1H, d, 8.0)
11.44 (s)
144.6
39.5
39.3
5.98 (1H, dd, 17.4, 10.7) 145.2 6.05 (1H, dd, 15.8, 9.1) 145.6
4.97 (1H, d, 17.4)
.96 (1H, d, 10.7)
111.7 5.01 (1H, d, 15.8)
5.03 (1H, d, 9.1)
112.1
4
2
2
3
4
1.39 (3H, s)
1.40 (3H, s)
27.5 1.45 (3H, s)
27.8 1.45 (3H, s)
27.9
27.9
b
a
Assignments were based on HSQC and HMBC experiments. Only
c
half of the NMR signal data of 1 was presented here. The NMR spectra
1
and 2 were recorded in C
D
5 5
N and in DMSO-d
6
, respectively.
1
drotryptophan moiety could be concluded from the H NMR
signals at δ 8.02 and 7.03 (each d, J ) 8.0 Hz, H-13, H-16),
7
.52 and 6.96 (each t, J ) 8.0 Hz, H-14, H-15), and the key
HMBC correlations of H-18 with C-11, C-12 and C-19, and
H-10 with C-3, C-4, C-11 and C-12. Besides the signals for
five C-atoms of isoprene unit and eleven C-atoms of
Figure 1. Structures of compounds 1-5.
1
3
dehydrotrytophan moiety, there were five C NMR signals
left for a proline moiety. The R-C (C-9) of proline residue
resonated at δ 102.2, suggesting that C-9 was oxygenated.
The ꢀ-C (C-8) presented to be a methylidyne, indicative of
a substitute at C-8. Therefore, it could be supposed that two
monomers were connected at C-8 and C-9. The structure of
compound 1 can not be determined only with NMR data.
The structure of 1 was finally determined to be a 2-fold dimer
as opposed to the mirror dimer on the basis of X-ray single
crystallographic analysis (Figure 2).
Brevianamide J (1) was obtained as colorless cubic
crystals. The UV spectrum with λmax in methanol at 201
4.44), 223 (4.49), 261 (4.18), and 349 (4.04) nm was
8
(
indicative of indole functionality with an extended conjuga-
9
tion. High-resolution ESIMS analysis of 1 suggested a
42 6 5
molecular formula of C42H N O . The NMR spectra of 1
revealed 21 protons and 21 C-atoms, suggesting 1 to be a
symmetric, homodimer (Table 1). The IR absorption bands
-1
at 1633, 1695, 3353, and 3423 cm are characteristic of
1
3
amides or lactams. The C NMR signals at δ 163.4 (C-1)
Brevianamide K (2) was isolated as yellow needle crystals.
and 161.4 (C-4) confirmed the presence of lactam carbonyls.
The molecular formula C21
H
23
N
3
O
2
was inferred from the
1
The H NMR signals at δ 4.96 (1H, d, J ) 10.7 Hz, H-22),
+
quasi-molecular ion peak at m/z 372.1679 [M + Na] in the
HRESIMS spectrum. The IR, UV, and NMR spectra were
very similar to those of compound 1. Signals for 21 proton
4
1
.97 (1H, d, J ) 17.4 Hz, H-22) and 5.98 (1H, dd, J ) 17.4,
0.7 Hz), and the HMBC correlations of methyls at δ 1.39
and 1.40 (each 3H, s, H-23 and H-24) with the C-atoms at
δ 39.3 (C-20), 105.3 (C-19) and 145.2 (C-21) suggested the
10
and 21 C-atoms were observed in the NMR spectra,
indicating that compound 2 could be the monomer of 1.
moiety of -C(CH
3
)
2
CHdCH
2
at C-19 (Table 1). A dehy-
13
Comparison of the C NMR spectra of compounds 1 and
2
, it was found that two C-atoms in 2 resonanted at δ 119.2
2
0
(
8) Compound 1: colorless cubic crystals; mp 226-227 °C; [R]
45.0° (c 0.10, acetone); UV (MeOH). λmax (log ε). 201(4.44), 223 (4.49),
61 (4.18), 349 (4.04). nm; IR(KBr). υmax: 3423, 3353, 2969, 2930, 1695,
D
+
2
1
(10) Compound 2: yellow needles; mp 157-158 °C; UV (MeOH). λmax
-
1
633, 1576, 1455, 1385, 749 cm ; 1H and 13C NMR data, see Table 1;
(log ꢀ). 201 (4.36), 225 (4.38), 283 (4.24), 367 (4.14). nm; IR(KBr). υmax:
+
-1
(
7
+)-HRESIMS m/z 733.3115 [M + Na] (calcd for C42
H N O
42 6 5
Na,
3427, 3367, 2968, 1673, 1638, 1617, 1424, 740 cm ; 1H and 13C NMR+
33.3109).
9) Dillman, R. L.; Cardellina, J. H., II J. Nat. Prod. 1991, 54, 1056.
data, see Table 1; (+)-HRESIMS (positive mode). m/z 370.1516 [M + Na]
(
21 3 2
(calcd for C21H N O Na, 370.1226).
Org. Lett., Vol. 11, No. 16, 2009
3715

group was located at C-15 in view of the HMBC correlations
of H-20 with C-1, C-15, and C-21. A double bond between
C-3 (δ 120.7) and C-4 was determined from the HMBC
correlations of H-17 and H-18/C-3, and H-16/C-3 and C-4
1
3
(
δ 117.0). The C NMR signal at δ 70.4 could be assigned
to C-12 from the HMBC correltions of H-10 and H-11 with
C-12. A double bond between N-5 and C-6 was suggested
by the HMBC correlations of H-8 and H-11 with C-6 (δ
1
53.4). The structure of compound 3 was elucidated by the
analysis of HSQC and HMBC spectra (Figure 3).
Figure 2. ORTEP diagram of compound 1.
(
C-8) and 134.2 (C-9) instead at δ 52.6 (C-8) and 102.2 (C-
9
) as those in 1. Thus, the presence of a bouble bond at C-8
and C-9 in 2 could be resumed. The above postulation was
confirmed by the HMBC correlations of H-8 with C-1 and
C-9, and H-6 and H-7 with C-9. The structure of compound
Figure 3. Key HMBC and NOESY correlations of 3.
2
was determined by HSQC and HMBC experiments.
Brevianamide L (3) was obtained as colorless cubic
crystals with a molecular formula C22
molecular ion peak at m/z 416.1576 [M + Na] in the
H
23
N
3
O
4
from the quasi-
The NOESY correlation between H-22/H-26 (δ 7.07, 2H,
m) and H-11 (δ 5.83, 1H, d, J ) 10.3 Hz) suggested that
relative orientation of H-11 and H-22 or H-26. L-Phenyla-
lanine was obtained from the hydrolysis of compound 3.
Thus, the absolute configurations of C-12 and C-15 were
determined respectively as S and R (Figure 3). It was
unsuccessful to abtain single crystal of compound 3. The
stereochemistry at C-16 was not determined so far.
+
-
1
HRESIMS. The IR peak at νmax 3420 cm suggested the
presence of hydroxyl group. The presence of amides could
be concluded from the IR peaks at νmax 3261, 1684, and 1667
-
1
13
cm , and the C NMR signals at δ 166.1 and 163.2. The
1
3
11
C NMR spectrum of 3 showed 22 signals. An oxepin
1
moiety could be concluded from H NMR signals of H-8,
H-9, H-10, and H-11, and the HMBC correlations of H-8/
C-6, H-10/C-12, and H-11/C-6, C-12, and C-13. Meanwhile,
the connections among C-3, C-4, C-16, C-17 and C-19 could
be deduced from the coupling system of H-18/H-16/H-17/
H-19, and the HMBC correlations of H-17 and H-18 with
C-3 (δ 120.7), and H-16 with C-3 and C-4 (δ 117.0). The
above information revealed that compound 3 was oxepin-
containing compound. Detailed comparison of the NMR data
of 3 with those of the A-C rings of oxepinamide A and
15 3 3
The molecular formula C18H N O of brevianamide M
(
3
4) was provided by the quasi-molecular ion peak at m/z
+
13
44.1014 [M + Na] in the HRESIMS. Its IR spectrum
-1
showed the presence of hydroxyl group (υmax 3421 cm ).
The C NMR signal at δ 169.6 and 160.4, and the IR peaks
at υmax 3362, 1694, and 1674 cm suggested the presence
13
-1
of amide carbonyls. A phenylalanine residue could be
1
concluded from the H NMR signals at δ 7.61 (2H, d, J )
7
5
.4 Hz), 7.26 (2H, t, J ) 7.4 Hz), 7.20 (1H, t, J ) 7.4 Hz),
.93 (1H, dd, J ) 9.1, 6.2 Hz), 3.83 (1H, dd, J ) 13.3, 6.2
1
2
cinereain supported this conclusion. Compound 3 was
hydrolyzed in 6 N HCl (aq.) for 12 h at 100 °C to afford
Hz) and 4.09 (1H, dd, J ) 13.3, 9.1 Hz), and the HMBC
correlation of H-15/C-14 (169.6), C-16 (137.6), C-17 (130.1),
and C-21 (130.1). Another ortho-substituted phenyl ring was
20
L-phenylalanine, [R]
D 2
-34.0 (c 0.1, H O), which was deter-
mined by comparing with an authentic sample. A benzyl
1
recognized from the H NMR signals at δ 8.40 and 7.88
2
0
(
11) Compound 3: colorless cubic crystals; mp 182-183 °C; [R]
190.0° (c 0.10, acetone); UV (MeOH). λmax (log ε). 201(4.03), 223 (4.12),
61 (3.15), 349 (3.76). nm; IR(KBr). υmax: 3420, 3261, 2960, 1684, 1667,
D
(each 1H, d, J ) 8.1 Hz), and 7.75 and 7.45 (each 1H, t, J
+
2
1
) 8.1 Hz). The connection of C-10/C-11/N-12/C-13 was
deduced from the HMBC correlation of H-9 and H-13/C-
11. The structure of compound 4 was finally confirmed by
X-ray crystallographic analysis (Figure 4). Compound 4 was
hydrolyzed in 6 N HCl (aq.) for 12 h at 100 °C to afford
L-phenylalanine. Therefore, the absolute configuration was
determined as 2S and 13S.
-
1
3
642, 1598, 1390, 1290, 700 cm ; 1H NMR (600 MHz, CDCl ). δ 8.40
(
6
1H, s, H-2), 7.20 (3H, m, H-23, 24 and 25), 7.07 (2H, m, H-22 and 26),
.61 (1H, d, 7.3, H-8), 6.19 (1H, dd, 10.3, 7.3, H-10), 5.83 (1H, d, 10.3,
H-11), 5.52 (1H, t, 7.3, H-9), 5.30 (1H, t, 5.3, H-15), 3.21(1H, dd, 13.8,
.3, H-20), 3.09, (1H, dd, 13.8, 5.3, H-20), 3.03 (1H, m, H-16), 1.42 (1H,
m, H-17), 1.51 (1H, m, H-17), 0.77 (3H, t, 7.2, H-19), 0.75 (3H, d, 7.2,
H-18);13C NMR (150 MHz, CDCl ). δ 165.8 (C-13), 164.7 (C-1), 153.4
C-6), 144.3 (C-8), 135.4 (C-21), 129.9 (C-22 and 26), 128.9 (C-10), 128.2
5
3
(
(
(
C-23 and 25), 126.9 (C-24), 120.7 (C-3), 117.0 (C-4), 105.2 (C-9), 132.0
C-11), 70.2 (C-12), 56.3 (C-15), 36.9 (C-20), 31.9 (C-16), 26.3 (C-17),
+
20
1
6.8(C-18), 11.1 (C-19); (+)-HRESIMS m/z 416.1576 [M + Na] (calcd
(13) Compound 4: colorless cubic crystals; mp 206-207 °C; [R]
D
for C22
H
23
N
3
O
4
Na, 416.1581).
-147.7° (c 0.13, acetone); UV (MeOH). λmax (log ꢀ). 208 (4.54), 222 (4.55),
269 (4.02), 304 (3.64). nm; IR(KBr). υmax: 3325, 3082, 2970, 1694, 1622,
1646, 1599, 1436, 1385, 918 cm ; 1H and 13C NMR data, see table 2
(12) (a) Belofsky, G. N.; Anguera, Jensen, M. P. R.; Fenical, W.; K o¨ ck,
-
1
M. Chem.sEur. J. 2000, 6, 1355. (b) Cutler, H. G.; Springer, J. P.;
Arrendale, R. F.; Arison, B. H.; Cole, P. D.; Roberts, R. G. Agric. Biol.
Chem. 1988, 52, 1725.
+
(+)-HRESIMS m/z 344.1014 [M + Na] (calcd for C18
15 3 3
H N O Na,
344.1006).
3716
Org. Lett., Vol. 11, No. 16, 2009

Table 2. NMR data of 4 and 5 ( H: 600 MHz; 13C: 150 MHz) ,
1
a b
4
5
no.
δ
H
(m, J ) Hz)
δ
C
δ
H
(m, J ) Hz)
δ
C
1
2
3
5
6
7
8
9
10.70 (1H, d, 4.9)
6.40 (1H, d, 4.9)
8.54 (1H, brs)
76.8
151.2
147.8
155.3
138.9
146.0
129.8
135.6
130.0
127.1
121.5
159.7
58.0
7.88 (1H, d, 8.1)
7.75 (1H, t, 8.1)
7.45 (1H, t, 8.1)
8.40 (1H, d, 8.1)
127.6 7.99 (1H, d, 8.1)
134.5 7.91 (1H, t, 8.1)
127.2 7.72 (1H, t, 8.1)
126.8 8.40 (1H, d, 8.1)
121.2
1
1
1
0
1
3
160.4
5.93 (1H, dd, 9.1, 6.2)
58.0 5.91 (1H, dd, 5.5, 3.0)
169.6
Figure 4
.
ORTEP diagram of compound 4.
14
166.8
1
1
5
6
3.83 (1H, dd, 13.3, 6.2) 40.6 3.46 (1H, dd, 14.1, 5.5) 38.4
4
.09 (1H, dd, 13.3, 9.1)
3.59 (1H, dd, 14.1, 3.0)
137.6
132.4
129.4
129.2
127.1
129.2
129.4
b
The molecular formula of brevianamide N (5) was
17 7.61(1H, d, 7.4)
1
1
20 7.26 (1H, t, 7.4)
21 7.61(1H, d, 7.4)
130.1 6.76 (1H, d, 7.5)
128.4 7.15 (1H, t, 7.5)
126.8 7.24 (1H, t, 7.5)
128.4 7.15 (1H, t, 7.5)
130.1 6.76 (1H, d, 7.5)
8
9
7.26 (1H, t, 7.4)
7.20 (1H, t, 7.4)
established as C18
at m/z 342.0853 [M + Na] in the HRESIMS, one more
H
15
N
3
O
3
from the quasi-molecular ion peak
+
1
4
unsaturated degree than 4. The NMR spectra and UV
absorptions at λmax at 221 (4.33), and 307.6 (3.89) nm of
compound 5 were close to those of 4. However, a ketonic
C-atom at δ 155.3 (C-2) presented in compound 5 rather
than an acetal C-atom as in 4 (Table 2). The structure of
compound 5 was finally elucidated by comparing the NMR
data with those of 4 and by HSQC and HMBC experiments.
The hydrolysis of compound 5 in 6 N HCl (aq.) yielded
L-phenylalanine, indicating that the absolute stereochemistry
of C-13 was S. The moiety of anthranilic acid in compounds
a
Assignments were based on HSQC and HMBC experiments. The
N, CDCl , respectively.
NMR spectra of 4 and 5 were recorded in C
5
D
5
3
Compounds 1-5 exhibited no cytotoxicity against human
breast cancer (Bre04), human lung (Lu04) or human neuroma
N04) cell lines (GI50 > 10 µg/mL), and no inhibitory activity
against Escherichia coli, Staphylococcus aureus, Pseudomo-
nas aeruginosa, or Candida albicans at a concentration of
100 µg/mL.
(
1
5
4
and 5 was present in some other diketopiperazines.
2
0
Acknowledgment. This work was supported by the West
Light Foundation of the Chinese Academy of Sciences.
(
14) Compound 5: colorless needles; 239-240 °C; [R]
.14, acetone); UV (MeOH). λmax (log ε). 221 (4.33), 307.6 (3.89). nm;
IR(KBr). υmax: 3420, 2922, 2854, 1739, 1710, 1690, 1595, 1467, 1326, 779
D
-359.3° (c
0
-
1
cm ; 1H and 13C NMR data, see table 3; (+)-HRESIMS m/z 342.0853
+
Supporting Information Available: HRESIMS, 1D and
2D NMR spectra of 1-5, and X-ray crystallographic data
of 1 and 4. This material is available free of charge via the
Internet at http://pubs.acs.org.
[
M + Na] (calcd for C18
(
13 3 3
H N O Na, 342.0849).
15) (a) Penn, J.; Mantle, P. G.; Bilton, J. N.; Sheppard, R. N. J. Chem.
Soc., Perkin Trans. 1 1992, 1495. (b) Fujimoto, H.; Negishi, E.; Yamaguchi,
K.; Nishi, N.; Yamazaki, M. Chem. Pharm. Bull. 1996, 44, 1843. (c) Chou,
T.-C.; Depew, K. M.; Zheng, Y.-H.; Safer, M. L.; Chan, D.; Helfrich, B.;
Zatorska, D.; Zatorski, A.; Bornmann, W.; Danishefsky, S. J. Proc. Natl.
Acad. Sci. U.S.A. 1998, 95, 8369.
OL901304Y
Org. Lett., Vol. 11, No. 16, 2009
3717