Zyzzyanones B-D, dipyrroloquinones from the marine sponge Zyzzya fuliginosa

Article abstract of DOI:10.1021/np050154y

Zyzzyanones B, C, and D (2-4), three new dipyrroloquinones with a pyrrolo[3,2-f]indole-4,8(1H,7H)dione skeleton, have been isolated from the Australian marine sponge Zyzzya fuliginosa. The known zyzzyanone A, makaluvamines C, E, G, H, and L, damirones A and B, 3,7-dimethylguanine, and 4-hydroxybenzoic acid were also isolated. The structures of the new compounds 2-4 were established by extensive NMR spectroscopic data. Compounds 2-4 showed moderate cytotoxic activity against mouse Ehrlich carcinoma cells (IC ₅₀ 25 μg/mL).

Full text of DOI:10.1021/np050154y

1424
J. Nat. Prod. 2005, 68, 1424-1427
Zyzzyanones B-D, Dipyrroloquinones from the Marine Sponge
Zyzzya fuliginosa
Natalia K. Utkina,* Aleksandra E. Makarchenko, and Vladimir A. Denisenko
Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Sciences,
690022 Vladivostok, Russian Federation
Received May 3, 2005
Zyzzyanones B, C, and D (2-4), three new dipyrroloquinones with a pyrrolo[3,2-f]indole-4,8(1H,7H)-
dione skeleton, have been isolated from the Australian marine sponge Zyzzya fuliginosa. The known
zyzzyanone A, makaluvamines C, E, G, H, and L, damirones A and B, 3,7-dimethylguanine, and
4-hydroxybenzoic acid were also isolated. The structures of the new compounds 2-4 were established by
extensive NMR spectroscopic data. Compounds 2-4 showed moderate cytotoxic activity against mouse
Ehrlich carcinoma cells (IC50 25 µg/mL).
The marine sponge Zyzzya fuliginosa (order Poecilo-
sclerida) is a rich source of alkaloids bearing a pyrrolo[4,
3,2-de]quinoline skeleton:1 makaluvamines,2-6 damirones,2,3,7
veiutamine,8 batzellines,9 isobatzellines,9 and discrhab-
dins.10 Moreover, makaluvic acids,11 ring-opened examples
of pyrrolo[4,3,2-de]quinolines, and purines11,12 were isolated
from this sponge. Recently, we have reported the isolation
and structure elucidation of zyzzyanone A (1), the first
pyrrolo[3,2-f]indole-4,8(1H,7H)-dione alkaloid from the
Australian marine sponge Zyzzya fuliginosa (Carter, 1879).13
The tricyclic dipyrroloquinone skeleton of zyzzyanone A (1)
is a seco-derivative of a tetracyclic dipyrroloquinoline core
of tsitsikammamines A and B, isolated from the South
African latrunculid sponge.14,15 To obtain more of zyzzy-
anone A to evaluate biological activities, we reinvestigated
the aqueous EtOH extract of the same sponge and have
isolated in addition to zyzzyanone A three new minor
dipyrroloquinones: zyzzyanone B (2), an N1-demethyl
analogue of zyzzyanone A; zyzzyanone C (3), an N11-formyl
analogue of zyzzyanone A; and zyzzyanone D (4), an N11-
formyl analogue of zyzzyanone B. The known makalu-
vamines C (9),2 E (7),2 G (5),6 H (8),3 and L (6),3 damirones
A (10) and B (11),7 3,7-dimethylguanine,12 and 4-hydroxy-
benzoic acid11 were also isolated. The known compounds
were identified by comparison of their spectral data with
published values. In this paper we report the structure
determination of the new compounds 2-4.
para-substituted phenol, two doublet signals in the aro-
matic region (δ 7.02 and δ 7.19) coupled with exchangeable
protons at δ 12.50 and 12.69, respectively; a triplet signal
from the only N-methyl group coupled with a broad signal
from two exchangeable protons at δ 8.42; and a pair of
triplets from two mutually coupled methylene groups, as
1
shown by the H-1H-COSY spectrum.
The freeze-dried sponge was extracted with 50% EtOH
at room temperature. The extract was separated as de-
scribed in the Experimental Section to obtain compounds
2 (0.002%), 3 (0.001%), and 4 (0.001%).
Compound 2, named zyzzyanone B, was obtained as a
purple TFA salt. The UV spectrum of zyzzyanone B was
similar to that of the known compound zyzzyanone A (1).13
Compound 2 gave a protonated molecular ion at m/z 336
by FABMS analysis, 14 atomic mass units less than 1.
HRFABMS measurements of the protonated pseudomo-
lecular ion (m/z 336.1339) suggested the molecular formula
C19H18N3O3. The 13C NMR and DEPT spectra revealed
signals for 19 carbon atoms and indicated the presence of
one methyl, two methylenes, six methines, and 10 quater-
nary carbons (Table 1). These data suggested the difference
between 2 and 1 was a single methyl group. The 1H NMR
spectrum of 2 (Table 2) contained proton signals of the
Comparison of the 1H and 13C NMR data of 2 with those
of 1 showed strong structural similarities between the two
molecules and suggested that compound 2 was an N1-
demethyl analogue of zyzzyanone A (1). Signals of the para-
substituted phenol in the 1H and 13C NMR spectra of 2 fully
coincided with those of 1. The presence of the protonated
methylaminoethyl chain in 2 was evident from the 1H-1H
COSY correlations in the proton spin system comprising
H2-9 (δ 3.00), H2-10 (δ 3.13), H2-N11 (δ 8.42), and H3-12 (δ
2.55). Full 1H and 13C NMR assignments were readily
* To whom correspondence should be addressed. Fax: (4232) 31 4050.
E-mail: utkinan@mail.ru.
10.1021/np050154y CCC: $30.25
© 2005 American Chemical Society and American Society of Pharmacognosy
Published on Web 08/16/2005

Notes
Journal of Natural Products, 2005, Vol. 68, No. 9 1425
Table 1. 13C NMR Data for Compounds 1-4 (DMSO-d6)
no.
1a
2
3
4
2
130.3 CH
119.6 C
125.4 C
180.4 C
121.4 C
126.6 C
123.9 CH
133.3 C
168.7 C
129.5 C
22.0 CH2
48.1 CH2
32.6 CH3
35.8 CH3
125.0 CHb
120.6 C
125.9 C
179.8 C
121.2 C
126.9 C
124.2 CH
133.3 C
169.4 C
131.5 C
22.3 CH2
48.2 CH2
32.7 CH3
130.4 CH, 130.0*c CH
121.5 C, 122.0* C
125.4 C, 125.5* C
180.4 C, 180.3* C
121.4 C
125.0 CH, 124.6* CH
122.5 C, 123.0* C
125.9 C, 126.0* C
179.8 C, 179.7* C
121.2 C
3
3a
4
4a
5
6
126.5 C, 126.4* C
123.8 CH, 123.7* CH
133.3 C
126.8 C, 126.7* C
124.1 CH, 124.0* CH
133.4 C
7a
8
8a
9
10
12
13
14
1′
2′
3′
4′
5′
6′
168.6 C, 168.7* C
129.4 C, 129.2* C
24.2 CH2, 22.6* CH2
48.6 CH2, 43.2* CH2
29.0 CH3, 34.0* CH3
35.8 CH3
169.3 C, 169.4* C
131.4 C, 131.2* C
24.5 CH2, 22.9* CH2
48.7 CH2, 43.3* CH2
29.1 CH3, 34.1* CH3
162.2 CH, 162.3* CH
124.0 C
162.3 CH, 162.4* CH
124.0 C
124.0 C
124.0 C
129.8 CH
114.6 CH
156.7 C
129.9 CH
114.6 CH
156.7 C
129.8 CH
129.9 CH
114.6 CH
114.6 CH
156.9 C
156.8 C
114.6 CH
129.8 CH
114.6 CH
129.9 CH
114.6 CH
114.6 CH
129.8 CH
129.9 CH
a Published data13 are given for comparison. b Multiplicities determined by DEPT. c Asterisks indicate additional signals of lower intensity
due to geometrical isomers.
Table 2. 1H NMR and HMBC Data for Compounds 2-4 (DMSO-d6)
2
3
4
no.
δ H (J)
HMBC
δ H (J)
HMBC
δ H (J)
6.95 s
HMBC
2
7.02 d (2.2)
3, 3a, 8a, 9
6.99 s
3, 3a, 4, 8, 8a, 9, 13
3, 3a, 4, 8, 8a, 9
7.01*a s
7.17 bs
2.89 m
3.45 m
2.76 s
6.97* s
7.17 bs
2.90 m
3.46 m
2.75 s
6
9
7.19 d (2.7)
3.00 t (7.5)
3.13 m
4a, 5, 7a, 1′
2, 3, 3a, 10
3, 9, 12
10
4, 4a, 5, 7a, 8
2, 3, 3a, 10
3, 9, 12, 14
10, 14
4, 4a, 5, 7a, 8
2, 3, 3a, 10
3, 9, 12, 14
10, 14
10
12
2.55 t (5.1)
2.88* s
3.89 s
7.78 s
7.95*
2.87* s
13
14
2, 8a
10, 12
7.78 s
7.95*
10, 12
N1H
N7H
N+11H2
OH
2′
12.50 d (2.2)
12.69 d (2.7)
8.42 m
3, 3a
4a, 5
12.49 bs
12.69 bs
12.60 bs
9.45 s
9.42 s
3′, 4′, 5′
5, 4′, 6′
1′, 4′, 5′
1′, 3′, 4′
5, 2′, 4′
9.42 s
3′, 4′, 5′
5, 4′, 6′
1′, 4′, 5′
1′, 3′, 4′
5, 2′, 4′
7.55 d (8.9)
6.74 d (8.9)
6.74 d (8.9)
7.55 d (8.9)
5, 4′, 6′
1′, 4′, 5′
1′, 3′, 4′
5, 2′, 4′
7.56 d (8.7)
6.75 d (8.7)
6.75 d (8.7)
7.56 d (8.7)
7.56 d (8.7)
6.75 d (8.7)
6.75 d (8.7)
7.56 d (8.7)
3′
5′
6′
a Asterisks indicate additional signals of lower intensity due to geometrical isomers.
obtained from HSQC and HMBC correlations and by
comparison with zyzzyanone A (Table 2). The doublet
resonance at δ 7.02 from the pyrrole proton, attached to a
carbon at δ 125.0 (1JCH ) 184 Hz), exhibited HMBC
correlations with all the carbons of the first pyrrole ring
(δ 120.6, 125.9, 131.5) and with the methylene carbon C-9
(δ 22.3) of the methylaminoethyl chain, indicating the
attachment of the chain to this ring. The key HMBC
correlation from the protons H2-10 (δ 3.13) to the carbon
atom of the pyrrole ring at δ 120.6 pointed to the position
of the methylaminoethyl chain being at C-3. The second
doublet resonance at δ 7.19 from the pyrrole proton,
attached to a carbon at δ 124.2 (1JCH ) 184 Hz), exhibited
HMBC correlations with all the carbons of the second
pyrrole ring (δ 121.2, 126.9, 133.3) and with the quaternary
carbon C-1′ (δ 124.0) of the para-substituted phenol,
indicating the attachment of the p-hydroxyphenyl moiety
to this pyrrole ring. The key HMBC correlations from the
protons H-2′(6′) at δ 7.55 of the phenol ring to the carbon
at δ 126.9 of the second pyrrole ring indicated the attach-
ment of the phenol moiety to this carbon (δ 126.6) and have
allowed assignment of this carbon as C-5. Comparison of
chemical shifts of carbonyl atoms C-4 and C-8 of 2 with
those of 1 showed that the chemical shift of the carbonyl
atom C-4 at δ 179.8 is diagnostic for a pyrrolo[3,2-f]indole-
4,8(1H,7H)-dione skeleton,13 and this allowed to ascribe
structure 2 to zyzzyanone B.
To confirm the structure of zyzzyanone B (2), we pre-
pared it from makaluvamine L (6). Treatment of an EtOH
solution of 6 with aqueous NH3 at room temperature for
20 h gave a mixture of products. Chromatography of the
reaction mixture yielded hydrolysis products of 6, damirone
B (11), makaluvamine C (9), and p-hydroxybenzoic acid,
and a cyclized product 2, the spectral and physical data of
which were identical with those for zyzzyanone B. Thus
the structure of 2 was confirmed.
Compound 3, named zyzzyanone C, was obtained as a
brownish-red solid, which gave a sodiated molecular ion
at m/z 400.1279 (M + Na)+ by HRFABMS analysis,
consistent with the molecular formula C21H19N3O4. Analy-
sis of NMR spectra of 3 showed that compound 3 was
structurally very similar to zyzzyanone A (1). The signals
of a p-hydroxyphenyl moiety in the 1H and 13C NMR
spectra coincided with those for zyzzyanone A (Tables 1
and 2). Except for the signals of the para-substituted
phenol, the NMR data for 3 were relatively complicated in

1426 Journal of Natural Products, 2005, Vol. 68, No. 9
Notes
1
contrast to the NMR data for 1. Most of the H and 13C
Zyzzyanones B-D described in this work deepen our
knowledge of the chemistry and biosynthetic capabilities
of marine organisms and add to the structural diversity of
alkaloids in marine sponges. Zyzzyanones A and B could
arise from makaluvamines G and L, respectively, by
intramolecular cyclization at the benzylic position with a
concomitant hydrolysis of an imino bond in hypothetical
analogues of tsitsikammamines. Zyzzyanones can be seen
to have a plausible interrelationship with the makalu-
vamines and with the tsitsikammamines. However, a facile
conversion of makaluvamines G and L to zyzzyanones A
and B in the presence of NH3 tentatively suggests a
possible formation of zyzzyanones during storage or isola-
tion.
resonances were doubled, indicating the presence of a 2:1
mixture of two isomers. Furthermore, the 13C NMR spec-
trum of 3, in contrast to 1, displayed additional carbon
signals of different intensities at δ 162.2 and 162.3 (Table
1
1). The H NMR spectrum of 3 (Table 2), in turn, differed
from the spectrum of 1 in the absence of a signal at δ 8.51
from two exchangeable protons and in the presence of two
singlet signals in a 2:1 ratio from one proton at δ 7.78 and
7.95. This finding correlated in the HSQC spectrum to the
carbon signals at δ 162.2 and 162.3, respectively, and had
1
coupling constants JCH ) 192 Hz, measured in gated
decoupling experiments, characteristic of an aldehyde
group. The assumption that this aldehyde group has to be
an N-formyl group was based on the presence of 3 as a
mixture of two isomers. In the 1H NMR spectrum of 3
recorded in DMSO-d6 at 150 °C, all doubled signals of
protons merged: δ 7.93 (1H, s, CHO), 7.05 (1H, s, H-6),
6.88 (1H, s, H-2), 3.50 (2H, t, J ) 7 Hz, CH2-10), 2.97 (2H,
t, J ) 7 Hz, CH2-9), 2.83 (3H, bs, CH3-12).
Zyzzyanones B-D showed moderate cytotoxic activity
against mouse Ehrlich carcinoma cells with IC50 values of
25 µg/mL. These data support the earlier suggestion that
the intact pyrroloiminoquinone moiety enhances cytotox-
icity.2,11
Experimental Section
The signals of the 1H and 13C NMR spectra were visually
differentiated and assigned to the major or minor isomers.
Comparison of the 13C NMR spectra of 3 and 1 showed that
significant differences in 13C chemical shifts occurred at
C-3 and carbons C-9, C-10, and C-12 of the side chain,
which strongly indicated that the formyl group had to be
at N11. This was supported by the HMBC correlations from
the proton of the formyl group at δ 7.78 to the carbon atom
at δ 48.6 (C-10) and to the carbon atom of the methyl group
at δ 29.0 (C-12) and from the protons at δ 3.45 (H2-10) and
at δ 2.76 (Me-12) to the carbon atom of the formyl group
at δ 162.2 of the major isomer (Table 2). The same
correlations were observed for signals of the minor isomer.
Detailed NMR spectroscopic analysis (DEPT, HSQC, and
HMBC) allowed the assignment of all the proton and
carbon values reported in Table 1 and Table 2. Thus, the
structure of zyzzyanone C (3) was determined as the N11-
formyl analogue of zyzzyanone A.
General Experimental Procedures. UV spectra were
recorded on an UV-mini 1240 spectrophotometer (Shimadzu).
1H NMR and 13C NMR spectra were recorded on a Bruker
AVANCE DRX-500 NMR spectrometer at 125 and 500 MHz,
respectively. Chemical shifts were referenced to the solvent
peak (DMSO-d6, 2.50 for 1H and 39.6 for 13C; CD3OD, 3.30 for
1H and 49.6 for 13C). HMBC spectra were optimized for 10 Hz
coupling. HRFABMS were performed on an AMD-604 S mass
spectrometer employing a glycerol matrix. Sorbfil plates coated
with Si gel (Sorbpolimer, Krasnodar, Russia) were used for
TLC; Sephadex LH-20 (Pharmacia Fine Chemicals) and Poly-
chrome-1 (powder Teflon, Olaine, Latvia) were used for column
chromatography. All solvents were distilled prior to use.
Animal Material. The sponge Z. fuliginosa was collected
by hand using scuba at Mid Islet, Eastern Australia, at a depth
of 10 m in July 1989 during the ninth scientific cruise of R/V
Academik Oparin. The sponge was freeze-dried and stored in
a refrigerator until used. The sponge was taxonomically
identified by Dr. V. B. Krasokhin. A voucher specimen (09-
407a) is held at Pacific Institute of Bioorganic Chemistry.
Extraction and Isolation. The freeze-dried sponge (200
g) was extracted with n-hexane to obtain the hexane solubles
(2 g), which were not examined. The sponge was then extracted
with 50% EtOH (1 L × 3) at room temperature, and the solvent
was concentrated under reduced pressure to yield a dark red
residue. This residue was triturated with CHCl3 to yield 1.2
g, which was chromatographed on a Sephadex LH-20 column
in CHCl3 to obtain in order of elution zyzzyanones D (4) (2
mg, 0.001% to the sponge dry weight) and C (3) (2 mg, 0.001%)
and damirones A (90 mg) and B (70 mg). A CHCl3-insoluble
solid was subjected to column chromatography on a Poly-
chrome-1 column with a solvent elution gradient from H2O to
EtOH. Dark red fractions eluted with 25-40% EtOH gave
makaluvamines C (10 mg, 0.005%) and H (34 mg, 0.017%) and
an additional quantity of damirones A (10 mg, 0.05%) and B
(10 mg, 0.04%) after chromatography on a Sephadex LH-20
column in CHCl3-EtOH-TFA (4:1:0.1%). A brownish-green
fraction eluted with 50% EtOH was repeatedly chromato-
graphed on a Sephadex LH-20 column in CHCl3-EtOH-TFA
(3:1:0.1%) to yield makaluvamines E (8 mg, 0.004%), G (110
mg, 0.055%), and L (16 mg, 0.008%), 3,7-dimethylguanine (9
mg, 0.0045%), zyzzyanone A (12 mg, 0.006%), and new
zyzzyanone B (2) (4 mg, 0.002%). Fractions eluted with EtOH
gave 4-hydroxybenzoic acid (7 mg, 0.0035%) after chromatog-
raphy on a Sephadex LH-20 column in EtOH.
Compound 4, named zyzzyanone D, was obtained as a
brownish-red solid; it gave a sodiated molecular ion at m/z
386.1124 (M + Na)+ by HRFABMS analysis, consistent
with the molecular formula C20H17N3O4. Like that of
1
zyzzyanone C (3), most H and 13C resonances of zyzzy-
anone D (4) were also doubled, indicating the presence of
a 2:1 mixture of two isomers. Comparison of the NMR data
of 4 with the NMR data of 3 showed that compound 4
differed only in the absence of one N1-methyl group. There
was an additional exchangeable proton signal at δ 12.49
in the 1H NMR spectrum of 3 instead of a singlet signal of
the N1-Me group at δ 3.89 of compound 4 (Table 1). The
significant upfield chemical shift of C-2 (∼∆ 5.4 ppm) in
the 13C NMR spectrum of 4 in comparison with the C-2
chemical shift of 3 supported the lack of the methyl group
at N1. Thus, the substitution pattern of a dipyrroloquinone
core of 4 was the same as that of zyzzyanone B (2). The
assignment of all the proton and carbon values was made
on the basis of detailed NMR spectroscopic analysis (DEPT,
HSQC, and HMBC). Thus, the structure of zyzzyanone D
(4) was determined as the N11-formyl analogue of zyzzy-
anone B.
The presence of an N-formyl group in marine metabolites
is common. Examples include N-formyl-1,2-dihydroreni-
erone from a marine sponge Reniera sp.16 and flustrabro-
mine from the marine bryozoan Flustra foliacea,17 which
were isolated as physically inseparable mixtures of two
geometrical isomers.
Zyzzyanone B (2): purple solid; UV-vis (MeOH) λmax (log
ꢀ) 240 (3.99), 281 (3.64), 328 (3.33), 483 (3.08) nm; UV-vis
(MeOH/KOH) λmax (log ꢀ) 241 (4.01), 281 (3.66), 332 (3.34), 503
1
(3.09) nm; H NMR (CD3OD) δ 7.54 (2H, d, J ) 8.6 Hz, H-2′,
6′), 7.04 (1H, s, H-6), 6.95 (1H, s, H-2), 6.77 (2H, d, J ) 8.6
Hz, H-3′, 5′), 3.26 (2H, t, J ) 6.4 Hz, CH2-10), 3.09 (2H, t, J )

Notes
Journal of Natural Products, 2005, Vol. 68, No. 9 1427
6.4 Hz, CH2-9), 2.69 (3H, s, CH3-12); 13C NMR (CD3OD) δ 183.9
(C, C-4), 170.3 (C, C-8), 158.6 (C, C-4′), 135.3 (C, C-7a), 134.3
(C, C-8a), 131.7 (CH, C-2′, 6′), 129.8 (C, C-5), 126.9 (C, C-3a),
126.6 (C, C-1′), 126.3 (CH, C-2), 125.5 (CH, C-6), 124.1 (C,
C-4a), 122.2 (C, C-3), 116.2 (CH, C-3′, 5′), 51.4 (CH2, C-10),
Acknowledgment. The authors are grateful to N. G.
Prokof’eva for bioassay, V. B. Krasokhin for sponge taxonomy,
and P. S. Dmitrenok for mass spectra measurements. This
research was supported by grants 03-04-49515 (RFBR), the
program “Molecular and Cell Biology” of the Presidium of the
Russian Academy of Sciences, and the grant scientific school-
725.2003.4 (The President of the Russian Federation).
1
34.4 (CH3, C-12), 24.5 (CH2, C-9); H and 13C NMR (DMSO-
d6) data, see Tables 1 and 2; HRFABMS m/z 336.1339 (calcd
for C19H18N3O3, 336.1343).
Zyzzyanone C (3): brownish-red solid; UV-vis (MeOH)
λmax (log ꢀ) 242 (3.67), 294 (3.24), 349 (2.94), 486 (2.85) nm;
UV-vis (MeOH/KOH) λmax (log ꢀ) 244 (3.63), 287 (3.22), 340
References and Notes
1
(2.93), 511 (2.86) nm; H and 13C NMR (DMSO-d6) data, see
(1) Antunes, E. M.; Copp, B. R.; Davies-Coleman, M. T.; Samaai, T. Nat.
Prod. Rep. 2005, 22, 62-72.
(2) Radisky, D. C.; Radisky, E. S.; Barrows, L. R.; Copp, B. R.; Kramer,
R. A.; Ireland, C. M. J. Am. Chem. Soc. 1993, 115, 1632-1638.
(3) Schmidt, E. W.; Harper, M. K.; Faulkner, D. J. J. Nat. Prod. 1995,
58, 1861-1867.
(4) Venables, D. A.; Concepcion, G. P.; Matsumota, S. S.; Barrows, L.
R.; Ireland, C. M. J. Nat. Prod. 1997, 60, 408-410.
(5) Casapullo, A.; Cutignano, A.; Bruno, I.; Bifulco, G.; Debitus, C.;
Gomez-Paloma, L.; Riccio, R. J. Nat. Prod. 2001, 64, 1354-1356.
(6) Carney, J. R.; Scheuer, P. J.; Kelly-Borges, M. Tetrahedron 1993, 49,
8483-8486.
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(8) Venables, D. A.; Barrows, L. R.; Lassota, P.; Ireland, C. M. Tetrahe-
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Tables 1 and 2; HRFABMS m/z 400.1279 (M+ + Na) (calcd for
C21H19N3O4 + Na, 400.1273).
Zyzzyanone D (4): brownish-red solid; UV-vis (MeOH)
λmax (log ꢀ) 241 (3.67), 288 (3.23), 337 (2.95), 487 (2.84) nm;
UV-vis (MeOH/KOH) λmax (log ꢀ) 243 (3.62), 282 (3.22), 326
(2.92), 510 (2.84) nm; 1H NMR (CD3OD) δ 7.96* and 7.79 (1H,
each s, CHO), 7.54 (2H, d, J ) 8.7 Hz, H-2′, 6′), 7.01 and 7.00*
(1H, each s, H-6), 6.87* and 6.85 (1H, each s, H-2), 6.77 (2H,
d, J ) 8.7 Hz, H-3′, 5′), 3.58 (2H, m, CH2-10), 2.98* and 2.89
(3H, each s, CH3-12), 3.01 (2H, m, CH2-9) (asterisks indicate
additional signals of the minor isomer); 13C NMR (CD3OD) δ
183.8 and 183.6* (C, C-4), 170.4 and 170.3* (C, C-8), 165.7
and 165.5* (CH, CHO-14), 158.5 (C, C-4′), 135.1 (C, C-7a),
134.1 (C, C-8a), 131.7 (CH, C-2′, 6′), 129.8 (C, C-5), 126.9 (C,
C-3a), 126.8 (C, C-1′), 126.4 and 126.0* (CH, C-2), 125.4 and
125.3* (CH, C-6), 124.5 and 124.3* (C, C-3), 124.3 (C, C-4a),
116.2 (CH, C-3′, 5′), 51.8 and 46.2* (CH2, C-10), 36.0* and 30.7
(CH3, C-12), 26.3 and 24.7* (CH2, C-9) (asterisks indicate
additional signals of the minor isomer); 1H and 13C NMR
(DMSO-d6) data, see Tables 1 and 2; HRFABMS m/z 386.1124
(M+ + Na) (calcd for C20H17N3O4 + Na, 386.1117).
Preparation of 2 from Makaluvamines L (6). A mixture
of 6 (27.8 mg), EtOH (20 mL), and aqueous 17% NH3 (3 mL)
was stirred at room temperature for 20 h. After evaporation
of the solvent the residue was chromatographed on a Sephadex
LH-20 column in CHCl3-EtOH-TFA (4:1:0.1%) to yield
damirone B (12.7%), makaluvamine C (4%), p-hydroxybenzoic
acid (10.4%), and the cyclized product 2 (4%). The UV,
HRFABMS, and 1H and 13C NMR data of 2 were identical with
those for zyzzyanone B.
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