Brartemicin, an inhibitor of tumor cell invasion from the actinomycete Nonomuraea sp.

Article abstract of DOI:10.1021/np9000575

Brartemicin (1), a new trehalose-derived metabolite, was isolated from the culture broth of the actinomycete of the genus Nonomuraea. Its structure and absolute configuration were determined by spectroscopic analyses. The new compound inhibited the invasi

Full text of DOI:10.1021/np9000575

980
J. Nat. Prod. 2009, 72, 980–982
Brartemicin, an Inhibitor of Tumor Cell Invasion from the Actinomycete Nonomuraea sp.1
Yasuhiro Igarashi,*,† Tsukasa Mogi,† Saeko Yanase,† Satoshi Miyanaga,† Tsuyoshi Fujita,‡ Hiroaki Sakurai,§ Ikuo Saiki,§ and
Ayumi Ohsaki⊥
Biotechnology Research Center, Toyama Prefectural UniVersity, 5180 Kurokawa, Imizu, Toyama 939-0398, Japan, Suntory Institute for
Bioorganic Research, 1-1-1 Wakayamadai, Shimamoto, Mishima, Osaka 618-8503, Japan, Department of Bioscience, Institute of Natural
Medicine, UniVersity of Toyama, 2630 Sugitani, Toyama 930-0194, Japan, and Institute of Biomaterials and Bioengineering, Tokyo Medical
and Dental UniVersity, 2-3-10 Surugadai, Kanda, Chiyoda-ku, Tokyo 101-0062, Japan
ReceiVed February 2, 2009
Brartemicin (1), a new trehalose-derived metabolite, was isolated from the culture broth of the actinomycete of the
genus Nonomuraea. Its structure and absolute configuration were determined by spectroscopic analyses. The new
compound inhibited the invasion of murine colon carcinoma 26-L5 cells with an IC50 value of 0.39 µM in a concentration-
dependent manner without showing cytotoxic effects.
Tumor metastasis is the process by which a tumor cell leaves
the primary tumor, disseminates to a distant site via the circulatory
system, and establishes a secondary tumor.2 In the metastatic
process, translocation of tumor cells across extracellular matrix
barriers, namely invasion, is a critical step to accomplish the
metastasis. The process of invasion is understood to include tumor
cell adhesion, enzymatic degradation of extracellular matrix
proteins, and migration. Inhibition of these steps is thus expected
as an effective approach to control metastasis and invasion.3 In
our continuing screening for antiinvasive compounds from natural
products,4 a new trehalose-containing metabolite was isolated from
the culture broth of the actinomycete Nonomuraea sp. The
producing strain N. sp. TP-A0870 was isolated from a leaf of the
Brazilian medicinal plant Artemisia Vulgaris. The strain was cultured
in our standard medium for actinomycetes,5 and the whole culture
broth was extracted with 1-butanol. The extract showed inhibitory
activity toward tumor cell invasion into Matrigel, the reconstituted
extracellular matrix proteins.6 Bioassay-guided fractionation of the
extract led to the purification of a new compound, brartemicin (1).
Compound 1 was obtained as a colorless powder, which had a
molecular formula of C28H34O17 by interpretation of high-resolution
FABMS ([M + H]+ m/z 643.1884) and NMR data. The IR spectrum
of 1 indicated the presence of hydroxyl (3320 cm-1) and ester (1620
cm-1) functionalities. The UV spectrum, with absorption bands at
λmax 216, 264, and 301 nm, was indicative of a benzoyl
was further supported by the upfield shifts of the ortho-carbons
C-8, C-10, and C-12. HMBC correlations from the H-14 methyl to
C-8, C-12, and C-13 allowed its location at C-13. The location of
the carbonyl group at C-7 was confirmed by the four-bond HMBC
correlations from H-10, H-12, and H-14, thus establishing the 2,4-
dihydroxy-6-methylbenzoyl moiety. The sugar and the aromatic
parts were connected between C-6 and C-7 through an ester bond
on the basis of an HMBC correlation from H-6 to C-7. Overall
analysis of the NMR data indicated that 1 possessed 14 carbons,
corresponding to one-half the number of carbons determined by
HRFABMS. Thus, it became clear that 1 was a symmetrical dimer
composed of two identical C14 units. Finally, a three-bond correla-
tion between H-1 (H-1′) and C-1′ (C-1) linked the two acylated
R-glucopyranosyl units to complete the structure of 1. Since 1 was
optically active, the two glucopyranosyl moieties should have the
same absolute configuration. R,R-D-Trehalose derivatives possessing
the same substituents at the 6- and 6′-positions are known to show
positive [R]D values. For example, 6,6′-ditosyl-D-trehalose8 and 6,6′-
dihexadecanoyl-D-trehalose9 show [R]D values of +90 and +78,
respectively. Thereby, the optical rotation of 1, [R]D +73, led to
the conclusion that the sugar moiety of 1 is R-D-glucopyranosyl-
R-D-glucopyranoside (R,R-D-trehalose). This was also supported by
the [R]D values of analogues (2: [R]D +94; 3: [R]D +105; 4: [R]D
+63. Scheme 1) that were synthesized from R,R-D-trehalose for a
structure-activity relationship study.
7
1
chromophore. H and 13C NMR analysis of 1 in combination with
the HMQC spectrum revealed the presence of 14 carbons including
three carbonyl or oxygenated sp2 carbons, four olefinic or aromatic
carbons, an oxygen-bearing methylene, five oxygen-bearing me-
thines, and a quaternary methyl. Further analysis of 1H-1H COSY
and HMBC spectra provided two distinctive units. The first part
was clearly a hexopyranose sugar moiety. The continuous COSY
correlations from H-1 to H-6 and an HMBC correlation from H-1
to C-5 established a hexopyranose ring. The large coupling constants
3JH,H for H-2/H-3, H-3/H-4, and H-4/H-5 revealed the axial-axial
relationship for these protons. The small coupling constant between
H-1 and H-2 (3.6 Hz) established the R-configuration at the
anomeric position, thereby establishing the relative configuration
of the sugar as an R-glucopyranoside. The second part was the
substituted benzene moiety. The downfield shifts of C-9 and C-11
indicated that these carbons possessed oxygen substitution, which
Invasion and cytotoxicity assays were carried out according to
the procedure previously described.4a Compound 1 inhibited the
invasion of murine colon carcinoma 26-L5 cells with an IC50 value
of 0.25 µg/mL ()0.39 µM). Cytotoxicity against the same cell line
was not detected even at 10 µg/mL. 1 possesses the hydroxylated
benzoyl moiety that is also contained in myxochelins and lupina-
cidins, invasion inhibitors found by us.4 In particular, the 2,3-
dihydroxybenzoyl substructure is common in 1 and the myxoch-
elins, leading to a speculation that these compounds have the same
mode of action. The process of invasion mainly consists of three
steps: cell adhesion, degradation of extracellular matrix, and cell
migration. Myxochelins inhibit the second step by inhibiting the
protease activity of MMP-2 and MMP-9, but 1 showed no effects
on these enzymes. In addition, lupinacidins inhibit the third step,
cell migration, but 1 did not. These findings indicate that the mode
of action of 1 is different from that of inhibitors previously reported.
To gain insights into the pharmacophore, a preliminary SAR
analysis was conducted for three analogues (2-4). These com-
pounds were synthesized by the coupling of a benzyl-protected R,R-
D-trehalose and an appropriate benzoate derivative, followed by
the removal of protecting groups by hydrogenolysis (Scheme 1).
Analogues 2, 3, and 4 at 1 µg/mL exhibited 51%, 35%, and 40%
* To whom correspondence should be addressed. Tel: +81-766-56-7500.
Fax: +81-766-56-2498. E-mail: yas@pu-toyama.ac.jp.
† Toyama Prefectural University.
‡ Suntory Institute for Bioorganic Research.
§ University of Toyama.
⊥ Tokyo Medical and Dental University.
10.1021/np9000575 CCC: $40.75  2009 American Chemical Society and American Society of Pharmacognosy
Published on Web 04/09/2009

Notes
Journal of Natural Products, 2009, Vol. 72, No. 5 981
Scheme 1a
a Reagents: (a) ArCOOH, DEAD, Ph3P or ArCOOH, EDAC, DMAP; (b) H2, Pd-C, MeOH.
Table 1. 1H and 13C NMR Data for Brartemicin (1) in CD3OD
inhibition, respectively, without showing cytotoxic effects, while
1 displayed 59% inhibition at the same concentration. These findings
indicated that the 6,6′-dibenzoyltrehalose-based structure is a novel
scaffold for the development of new antiinvasive agents.
a
,
position
δC
δH mult (J in Hz)b
HMBCb c
1, 1′
2, 2′
3, 3′
4, 4′
5, 5′
6, 6′
95.6, CH
73.2, CH
74.5, CH
72.2, CH
71.4, CH
65.4, CH2 4.58, dd (12.0, 2.2)
4.46, dd (12.0, 4.9)
172.8, qC
5.13, d (3.6)
1′ (1), 2 (2′), 5 (5′)
3 (3′), 4 (4′)
3.49, dd (9.5, 3.6)
3.85, dd (9.5, 9.0)
3.44, dd (10.0, 9.0)
1 (1′), 2 (2′), 4 (4′)
3 (3′), 5 (5′), 6 (6′)
Experimental Section
4.19, ddd (10.0, 4.9, 2.2) 3 (3′), 4 (4′)
General Experimental Procedures. Optical rotations were measured
using a JASCO DIP-3000 polarimeter. The UV spectrum was recorded
on a Hitachi U-3210 spectrophotometer. The IR spectrum was measured
on a Perkin-Elmer Spectrum 100. NMR spectra were obtained on a
Bruker AVANCE 400 or a Bruker AVANCE 500 spectrometer, using
the signals of the residual solvent protons and carbons as internal
standard. HRFABMS was measured on a JEOL JMS-HX110 spec-
trometer. HRESITOFMS were recorded on a Bruker microTOF focus.
Silica gel 60-C18 (Nakalai Tesque 250-350 mesh) was used for ODS
column chromatography. HPLC separation was performed using a
Cosmosil 5C18-AR-II (Nacalai Tesque Inc., 20 × 250 mm) with a
photodiode array detector.
Microorganism. Strain TP-A0870 was isolated from a dried leaf
of Artemisia Vulgaris L. purchased in Sa˜o Paulo, Brazil. A voucher
specimen (No. B-042) with identification has been deposited at the
Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental
University (Chiyoda-ku, Tokyo). The strain was identified as a member
of the genus Nonomuraea on the basis of 99.3% 16S rRNA gene
sequence (1483 nucleotides; DDBJ accession number AB449973)
identity with the N. bangladeshensis type strain (accession number
AB274966).
Fermentation. Strain TP-A0870 cultured on a slant agar medium
was inoculated into 500 mL K-1 flasks each containing 100 mL of the
seed medium consisting of soluble starch 1%, glucose 0.5%, NZ-case
0.3%, yeast extract 0.2%, tryptone (Difco Laboratories) 0.5%, K2HPO4
0.1%, MgSO4 ·7H2O 0.05%, and CaCO3 0.3% (pH 7.0). The flasks were
cultivated on a rotary shaker (200 rpm) at 30 °C for 4 days. The seed
culture (3 mL) was transferred into 500 mL K-1 flasks each containing
100 mL of the production medium consisting of glucose 0.5%, glycerol
2%, soluble starch 2%, Pharmamedia (Traders Protein) 1.5%, yeast
extract 0.3%, and Diaion HP-20 (Mitsubishi Chemical Co.) 1%. The
pH of the medium was adjusted to 7.0 before sterilization. The
inoculated flasks were cultured on a rotary shaker (200 rpm) at 30 °C
for 6 days.
Extraction and Isolation. At the end of the fermentation period,
50 mL of 1-butanol was added to each flask, and they were allowed to
shake for 1 h. The mixture was centrifuged at 6000 rpm for 10 min,
and the organic layer was separated from the aqueous layer containing
the mycelium. Evaporation of the solvent gave approximately 2.0 g of
extract from 1 L of culture. The crude extract (20 g) was subjected to
4 (4′), 5 (5′), 7 (7′)
5 (5′), 7 (7′)
7, 7′
8, 8′
105.6, qC
166.3, qC
101.7, CH 6.15, d (2.4)
9, 9′
10, 10′
7 (7′), 8 (8′), 9 (9′),
11 (11′), 12 (12′)
11, 11′
12, 12′
163.9, qC
112.6, CH 6.21, d (2.4)
7 (7′), 8 (8′), 10 (10′),
11 (11′), 14 (14′)
13, 13′
14, 14′
144.9, qC
24.9, CH3 2.51, s
7 (7′), 8 (8′), 9 (9′),
12 (12′), 13 (13′)
a Recorded at 100 MHz. b Recorded at 500 MHz. c HMBC
correlations are from proton(s) stated to the indicated carbon.
silica gel column chromatography with a step gradient of CHCl3/MeOH
(1:0, 20:1, 10:1, 4:1, 2:1, 1:1, and 0:1 v/v). Fraction 6 was concentrated
to provide 2.0 g of brown powders, which were further purified by
reversed-phase ODS column chromatography with a gradient of MeCN/
0.15% KH2PO4 buffer (pH 3.5) (2:8, 3:7, 4:6, 5:5, 6:4, 7:3, and 8:2
v/v). Fractions 3 and 4 were combined and evaporated. The remaining
aqueous solution was extracted with 1-butanol, and the organic layer
was concentrated to give semipure 1 as a major component. Final
purification of 1 was achieved by repeated C-18 RP HPLC with MeCN/
H2O (30:70), followed by evaporation and lyophilization. Typical
recovery of 1 from a 1 L culture was 3.1 mg.
Brartemicin (1): colorless powder; [R]24D +73 (c 0.5, MeOH); UV
(MeOH) λmax (log ꢀ) 216 (4.77), 264 (4.53), 301 (4.14) nm; IR (film)
ν
max 3320, 1620 cm-1; 1H and 13C NMR data, see Table 1; HRFABMS
[M + H]+ 643.1884 (calcd for C28H35O17, 643.1875).
6,6′-Dibenzoyl-r,r-D-trehalose (2). Triphenylphosphine (45 mg,
0.17 mmol), benzoic acid (20 mg, 0.17 mmol), and diethyl azodicar-
boxylate (40% solution in toluene, 77 µL, 0.17 mmol) were added to
a stirred solution of 2,2′,3,3′,4,4′-hexabenzyl-R,R-D-trehalose10 (5, 50
mg, 0.057 mmol) in dry THF (1 mL) at 0-5 °C. After stirring for 2 h
at the same temperature, the reaction mixture was diluted with
ice-water and extracted with EtOAc. The organic layer was dried over
anhydrous MgSO4, filtered, and concentrated. The residue was purified
by silica gel column chromatography (hexane/EtOAc, 10:1-1:1) to give

982 Journal of Natural Products, 2009, Vol. 72, No. 5
Notes
1
6 (60 mg) in 96% yield: [R]24 +83 (c 1.0, CHCl3); H NMR (400
6,6′-Bis(2,3-dihydroxybenzoyl)-r,r-D-trehalose (4). In the same
manner as described for 6, 5 and 2,3-dibenzyloxybenzoic acid11 gave
8 in 56% yield: [R]24D +45 (c 1.0, CHCl3); 1H NMR (400 MHz, CDCl3)
δ 7.16-7.48 (23H, m), 5.10 (1H, d, J ) 3.5 Hz), 5.09 (4H, m), 4.98
(1H, d, J ) 10.8 Hz), 4.84 (1H, d, J ) 10.8 Hz), 4.83 (1H, d, J ) 10.6
Hz), 4.59 (2H, s), 4.53 (1H, d, J ) 10.6 Hz), 4.38 (1H, dd, J ) 12.0,
3.2 Hz), 4.27 (2H, m), 4.04 (1H, t, J ) 9.3 Hz), 3.62 (1H, t, J ) 9.6
Hz), 3.44 (1H, dd, J ) 9.6, 3.5 Hz); 13C NMR (100 MHz, CDCl3) δ
165.6, 152.9, 157.8, 138.7, 138.0, 137.9, 137.6, 128.8, 128.63, 128.55,
128.44, 128.40, 128.3, 128.2, 128.0, 127.6, 127.5, 127.4, 123.9, 122.8,
119.4, 118.0, 93.9, 81.6, 79.4, 77.7, 75.8, 75.3, 72.9, 71.4, 71.2, 69.3,
D
MHz, CDCl3) δ 8.13 (2H, dd, J ) 8.5, 1.2 Hz), 7.95 (2H, dd, J ) 8.5,
1.2 Hz), 7.62 (1H, tt, J ) 7.2, 1.2 Hz), 7.54 (1H, tt, J ) 7.2, 1.2 Hz),
7.48 (2H, t, J ) 7.4 Hz), 7.23-7.42 (12H, m), 5.23 (1H, d, J ) 3.6
Hz), 5.04 (1H, d, J ) 10.7 Hz), 4.91 (1H, d, J ) 10.7 Hz), 4.90 (1H,
d, J ) 10.7 Hz), 4.74 (1H, d, J ) 11.9 Hz), 4.70 (1H, d, J ) 11.9 Hz),
4.59 (1H, d, J ) 10.7 Hz), 4.35 (1H, m), 4.34 (1H, d, J ) 12.7 Hz),
4.27 (1H, dd, J ) 12.7, 3.8 Hz), 4.12 (1H, t, J ) 9.3 Hz), 3.69 (1H, t,
J ) 9.3 Hz), 3.63 (1H, dd, J ) 9.6, 3.6 Hz); 13C NMR (100 MHz,
CDCl3) δ 166.2, 138.5, 137.84, 137.81, 133.1, 129.9, 129.65, 128.54,
128.52, 128.50, 128.4, 128.2, 128.1, 128.0, 127.82, 127.78, 127.4, 94.0,
81.8, 79.6, 77.7, 75.9, 75.3, 73.1, 69.3, 63.1; HRESITOFMS m/z [M
+ Na]+ 1113.4387 (calcd for C68H66O13Na, 1113.4395).
63.2; HRESITOFMS m/z [M
+
Na]+ 1537.6068 (calcd for
C96H90O17Na, 1537.6070).
To a solution of 6 (20 mg, 0.044 mmol) in MeOH/THF (1:1, 5 mL)
was added 10% Pd/C (10 mg), and the mixutre was stirred at room
temperature under an atmosphere of H2 for 2 h. The reaction mixture
was filtered through Celite and concentrated under reduced pressure.
The residue was purified by preparative HPLC in the same manner as
In the same manner as described for 2, 8 gave 4 in 90% yield: [R]24
D
1
+63 (c 0.57, MeOH); H NMR (500 MHz, CD3OD) δ 7.40 (1H, dd,
J ) 8.0, 1.2 Hz), 7.02 (1H, dd, J ) 8.0, 1.2 Hz), 6.76 (1H, t, J ) 8.0
Hz), 5.12 (1H, d, J ) 3.7 Hz), 4.63 (1H, dd, J ) 11.9, 1.8 Hz), 4.50
(1H, dd, J ) 11.9, 4.8 Hz), 4.21 (1H, ddd, J ) 10.1, 4.8, 1.8 Hz), 3.84
(1H, dd, J ) 9.3 Hz), 3.53 (1H, dd, J ) 9.7, 3.7 Hz), 3.47 (1H, dd, J
) 9.5 Hz); 13C NMR (100 Hz, CD3OD) δ 171.5, 151.3, 147.2, 121.8,
121.4, 120.1, 114.0, 95.6, 74.7, 73.2, 71.9, 71.4, 65.3; HRESITOFMS
m/z [M + Na]+ 637.1369 (calcd for C26H30O17Na, 637.1375).
described for 1 to yield 2 (14 mg) in 46% yield: [R]24 +94 (c 1.0,
D
1
MeOH); H NMR (CD3OD, 500 MHz) δ 8.03 (2H, d, J ) 7.5 Hz),
7.60 (1H, t, J ) 7.5 Hz), 7.47 (2H, t, J ) 7.5 Hz), 5.13 (1H, d, J ) 3.7
Hz), 4.59 (1H, dd, J ) 11.9, 1.8 Hz), 4.47 (1H, dd, J ) 11.9, 5.0 Hz),
4.21 (1H, ddd, J ) 10.0, 5.0, 1.8 Hz), 3.85 (1H, t, J ) 9.3 Hz), 3.54
(1H, dd, J ) 9.7, 3.7 Hz), 3.49 (1H, t, J ) 9.5 Hz); 13C NMR (CD3OD,
100 MHz) δ 168.0, 134.3, 131.4, 130.6, 129.6, 95.5, 74.7, 73.2, 72.0,
71.7, 65.1; HRESITOFMS m/z [M + Na]+ 573.1594 (calcd for
C26H30O13Na, 573.1579).
Acknowledgment. We thank to Dr. G. Hashimoto (Centro de
Pesquisas de Histo´ria Natural, Sa˜o Paulo, Brazil) for identification of
plant specimens.
1
Supporting Information Available: H and 13C NMR spectra of
6,6′-Bis(2-hydroxybenzoyl)-r,r-D-trehalose (3). To a stirred solu-
tion of 5 (50 mg, 57 µmol) in dry DMF (2 mL) were added N-(3-
dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (55 mg, 0.29
mmol), 2-benzyloxybenzoic acid (39 mg, 0.17 mmol), and 4-(dim-
ethylamino)pyridine (35 mg, 0.29 mmol) at room temperature. After
stirring for 3 h, the reaction mixture was diluted with ice-water and
extracted with EtOAc. The organic layer was dried over anhydrous
MgSO4, filtered, and concentrated under reduced pressure. The residue
was purified by silica gel column chromatography (hexane/EtOAc, 10:
1-1:1) to give 7 (61 mg) in 75% yield: [R]24D +63 (c 1.0, CHCl3); 1H
NMR (500 MHz, CDCl3) δ 7.73 (1H, dd, J ) 8.0, 1.8 Hz), 7.42 (2H,
d, J ) 7.3 Hz), 7.20-7.39 (19H, m), 6.93 (2H, m), 5.17 (1H, d, J )
3.5 Hz), 5.16 (2H, s), 5.00 (1H, d, J ) 10.8 Hz), 4.86 (1H, d, J ) 10.9
Hz), 4.82 (1H, d, J ) 10.5 Hz), 4.61 (2H, s), 4.56 (1H, d, J ) 10.5
Hz), 4.41 (1H, dd, J ) 12.3, 3.5 Hz), 4.32 (1H, m), 4.31 (1H, d, J )
12.3 Hz), 4.06 (1H, t, J ) 9.5 Hz), 3.70 (1H, t, J ) 9.5 Hz), 3.50 (1H,
dd, J ) 9.7, 3.6 Hz); 13C NMR (100 MHz, CDCl3) δ 165.8, 158.1,
138.7, 138.0, 137.8, 136.7, 133.4, 131.7, 128.6, 128.5, 128.4, 128.2,
127.9, 127.75, 127.72, 127.6, 127.5, 126.7, 120.6, 120.5, 113.8, 93.9,
81.6, 79.3, 77.7, 75.6, 75.2, 72.8, 70.3, 69.4, 63.1; HRESITOFMS m/z
[M + Na]+ 1325.5218 (calcd for C82H78O15Na, 1325.5238).
brartemicin. This material is available free of charge via the Internet
at http://pubs.acs.org.
References and Notes
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Bioorg. Med. Chem. Lett. 2007, 17, 3702–3705. (c) Miyanaga, S.;
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764–767.
(6) Saito, K. I.; Oku, T.; Ata, N.; Miyashiro, H.; Hattori, M.; Saiki, I.
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Chem. Soc. Jpn. 1989, 62, 3026–3028.
In the same manner as described for 2, 7 gave 3 in 90% yield: [R]24
+110 (c 0.6, MeOH); H NMR (500 MHz, CD3OD) δ 7.90 (1H, dd,
D
1
J ) 8.0, 1.7 Hz), 7.48 (1H, ddd, J ) 8.4, 7.3, 1.3 Hz), 6.94 (1H, dd,
J ) 8.4, 1.3 Hz), 6.91 (1H, ddd, J ) 8.0, 7.3, 1.3 Hz), 5.12 (1H, d, J
) 3.7 Hz), 4.62 (1H, dd, J ) 11.8, 2.2 Hz), 4.50 (1H, dd, J ) 11.8,
5.1 Hz), 4.22 (1H, ddd, J ) 10.1, 5.1, 2.2 Hz), 3.84 (1H, t, J ) 9.4
Hz), 3.53 (1H, dd, J ) 9.7, 3.7 Hz), 3.46 (1H, dd, J ) 10.1, 9.0 Hz);
13C NMR (100 MHz, CD3OD) δ 170.3, 162.0, 136.1, 130.4, 119.6,
117.6, 112.9, 94.9, 73.9, 72.4, 71.1, 70.7, 64.5; HRESITOFMS m/z
[M + Na]+ 605.1465 (calcd for C26H30O15Na, 605.1476).
(11) Kanai, F.; Isshiki, K.; Umezawa, Y.; Morishima, H.; Naganawa, H.;
Takita, T.; Takeuchi, T.; Umezawa, H. J. Antibiot. 1985, 38, 31–38.
NP9000575