Quadoctomycin, a 48-membered macrolide antibiotic from Streptomyces sp. MM168-141F8

Article abstract of DOI:10.1038/ja.2017.140

Drug-resistant bacteria are still emerging, and screening of new skeletal antibiotics is important. During our continuous screening for antimicrobial agents, we discovered a new antimicrobial, named quadoctomycin, from solid culture of Streptomyces sp. MM168-141F8. The substance was purified by solvent extraction, silica gel chromatography and HPLC. Structural elucidation of quadoctomycin was performed by MS and NMR analyses and chemical degradation. Quadoctomycin possesses a 48-membered polyol macrolide skeleton in which an α-D-mannoside is connected to C-22 by an O-glycosidic linkage. The structure of quadoctomycin was found to be related to that of monazomycin A based on the analyses of NMR spectra in the same solvent (pyridine-d 5). Quadoctomycin showed potent antibacterial activity against Staphylococcus aureus, including methicillin-resistant S. aureus, and other Gram-positive pathogenic bacteria such as Enterococcus faecalis and E. faecium (including drug-resistant strains), but did not show activity toward Gram-negative bacteria or Candida albicans.

Full text of DOI:10.1038/ja.2017.140

The Journal of Antibiotics (2017), 1–6
2017 Japan Antibiotics Research Association All rights reserved 0021-8820/17
www.nature.com/ja
&
ORIGINAL ARTICLE
Quadoctomycin, a 48-membered macrolide antibiotic
from Streptomyces sp. MM168-141F8
Ryuichi Sawa, Yumiko Kubota, Maya Umekita, Masaki Hatano, Chigusa Hayashi
and Masayuki Igarashi
Drug-resistant bacteria are still emerging, and screening of new skeletal antibiotics is important. During our continuous screening
for antimicrobial agents, we discovered a new antimicrobial, named quadoctomycin, from solid culture of Streptomyces sp.
MM168-141F8. The substance was purified by solvent extraction, silica gel chromatography and HPLC. Structural elucidation of
quadoctomycin was performed by MS and NMR analyses and chemical degradation. Quadoctomycin possesses a 48-membered
polyol macrolide skeleton in which an α-D-mannoside is connected to C-22 by an O-glycosidic linkage. The structure of
quadoctomycin was found to be related to that of monazomycin A based on the analyses of NMR spectra in the same solvent
(
pyridine-d ). Quadoctomycin showed potent antibacterial activity against Staphylococcus aureus, including methicillin-resistant
5
S. aureus, and other Gram-positive pathogenic bacteria such as Enterococcus faecalis and E. faecium (including drug-resistant
strains), but did not show activity toward Gram-negative bacteria or Candida albicans.
The Journal of Antibiotics advance online publication, 15 November 2017; doi:10.1038/ja.2017.140
INTRODUCTION
search for antibiotics with new structures from natural products is
Antimicrobial resistance has become a global problem that crosses expected to be one approach to developing useful and innovative new
national borders. In 2011, the Director General of the World Health drugs for overcoming antimicrobial resistance.3,4 Indeed, the devel-
Organization issued an important warning about antimicrobial opment and launch of several such antimicrobials effective against
resistance and a coming global crisis: "no action today means no cure
tomorrow”. In 2013, the US Centers for Disease Control and
multidrug-resistant M. tuberculosis will be a change in the current
treatment regimen.5,6
1
Prevention enumerated several pathogens that are considered a serious
threat and for which effective antibiotic development is urgently
needed. These bacteria include Clostridium difficile, carbapenem-
resistant Enterobacteriaceae, extended spectrum β-lactamase-produ-
cing Enterobacteriaceae, drug-resistant Neisseria gonorrhoeae,
multidrug-resistant Acinetobacter, drug-resistant Campylobacter,
vancomycin-resistant Enterococcus, multidrug-resistant (MDR) Pseu-
domonas aeruginosa, drug-resistant non-typhoidal Salmonella, drug-
resistant Salmonella typhi, drug-resistant Shigella, methicillin-resistant
Staphylococcus aureus, drug-resistant Streptococcus pneumoniae and
During our screening for antibiotics with a new skeleton and/or
new mechanism(s) of action against antimicrobial resistance, we found
a novel 48-membered macrolide, named quadoctomycin (Figure 1), in
the solid culture material of a Streptomyces strain. In this paper, we
describe the taxonomy and fermentation of the producing strain, and
the isolation, structure elucidation and biological activities of
quadoctomycin.
RESULTS AND DISCUSSION
Screening
2
multidrug-resistant Mycobacterium tuberculosis.
In continuous screening for new antimicrobial substances against
various test organisms, we found antibacterial activity against Gram-
positive bacteria including methicillin-resistant S. aureus in the solid
culture material of strain MM168-141F8, isolated from a soil sample
collected in Shinagawa-ku, Tokyo, Japan. Small-scale culture of the
Conventionally, to overcome drug-resistant bacteria, development
of next-generation semi-synthetic antibiotics has been carried by
limited modification of existing antibiotic skeletons. However, as
these superbugs spread more quickly than anticipated, it is becoming
difficult to overcome resistance by this method. Compounds with new
skeletons and mechanisms of action are becoming the scaffolds for the strain was extracted with n-butanol and the dried extract was purified
drug discovery process and they bring about changes to current by semi-preparative HPLC. It was suggested that the active fractions
chemotherapy. Natural products have the potential to present novel gave a protonated molecule with m/z 1436.9961 by HPLC-high
chemical scaffolds and provide new leads to organic chemists. The resolution ESI/MS (HRESI/MS). This molecule is not described in
Institute of Microbial Chemistry (BIKAKEN), Tokyo, Japan
Correspondence: Dr R Sawa or Dr M Igarashi, Institute of Microbial Chemistry (BIKAKEN), Tokyo, Laboratory of Molecular Structure Analysis or Laboratory of Microbiology,
3
-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan.
E-mail: rsawa@bikaken.or.jp or
E-mail: igarashim@bikaken.or.jp
Received 18 July 2017; revised 27 September 2017; accepted 4 October 2017

A new 48-membered macrolide, quadoctomycin
R Sawa et al
2
OH
HO
OH
O
3
'
HO 6'
O
1'
OH OH
OH
OH
OH
4
8
10
12
16
20
2
2
24
1
OH
O
O
OH OH OH OH OH OH
OH
OH
OH
H2N 56
50
44
40
36
32
28
53
47
quadoctomycin
OH
HO
OH
O
3
'
HO 6'
O
1'
OH OH
OH
OH
OH
4
8
10
12
16
20
2
2
24
1
O
O
OH OH OH OH OH OH
OH
OH
OH
R
54
50
44
40
36
32
28
47
monazomycin A R = NH2
monazomycin B R = NHC
NH
NH2
Figure 1 Structures of quadoctomycin and monazomycins.
1
6S rRNA gene sequence of strain MM168-141F8 is LC270914. The
strain showed high similarity with those of the genus Streptomyces,
T
T
such as S. djakartensis NBRC 15409 (1417/1419 bp, 99.86%; : Type
T
strain) and Streptomyces tuirus NBRC 15617 (1413/1420 bp, 99.51%).
These phenotypic and genotypic data suggested that strain MM168-
1
41F8 belongs to the genus Streptomyces. Therefore, the strain was
tentatively designated Streptomyces sp. MM168-141F8.
Fermentation and isolation
Quadoctomycin was monitored using antimicrobial activity against S.
aureus Smith. The fermentation of quadoctomycin was carried out in
solid culture. A total of 7 ml of seed culture was transferred into
1
4 K-1 flasks each containing 40 g of production medium. The
fermentation was carried out at 30 °C for 14 days in the dark. The
producing culture (560 g) was extracted with acetone and the extract
was concentrated. Water was added and the mixture was extracted
with n-butanol. The organic layer was concentrated and the residue
was partitioned with n-hexane/methanol. As the antimicrobial activity
was in the methanol layer, the methanol solution was concentrated to
dryness to obtain a brown solid (1 g). The residue was applied to a
Figure 2 Scanning electron micrograph of strain MM168-141F8 after growth
on oatmeal agar (ISP medium No. 3) for 8 days at 30 °C. Bar, 1 μm.
the Dictionary of Natural Products database. Therefore, we decided to silica gel column and eluted with chloroform/methanol/H2O to yield
isolate this active substance.
339 mg of light-brown solid. The solid, containing quadoctomycin,
was further purified by HPLC, which was developed with 35%
acetonitrile aqueous solution containing 0.01% trifluoroacetic acid
Taxonomy of the antibiotics-producing strain
On oatmeal agar (ISP medium No. 3), strain MM168-141F8 formed to give 55 mg of quadoctomycin as a white powder.
well-branched substrate mycelia and straight to flexuous aerial
mycelia. The substrate mycelia were light beige, the aerial mycelia Structure determination
were bayberry gray. Mature spore chains consisted of 5– ⩾ 20 spores. The physicochemical properties of quadoctomycin are summarized in
The spores were cylindrical to oval with a spiny surface and 0.7 × 1.0– the Materials and Methods section. The optical rotation of the
1
.0 × 1.2 μm in size (Figure 2). The diaminopimelic acid isomers in compound was +15° (c 0.5, methanol). It did not show a characteristic
whole-cell hydrolysates of strain MM168-141F8 were determined to be UV spectrum. The molecular formula of quadoctomycin was deter-
1
13
the LL-form. A partial 16S ribosomal RNA gene sequence (1425 bp) mined to be C H141NO23 by HRESI/MS. Although the H and
C
7
6
was determined. The GenBank/EMBL/DDBJ accession number for the NMR spectra of quadoctomycin in methanol-d initially showed a
4
The Journal of Antibiotics

A new 48-membered macrolide, quadoctomycin
R Sawa et al
3
The Journal of Antibiotics

A new 48-membered macrolide, quadoctomycin
R Sawa et al
4
OH
O
HO
HO
OH
O
OH OH
OH
OH
OH
OH
O
O
OH OH OH OH OH OH
OH
OH
OH
H2N
COSY
HSQC-TOCSY
HMBC
ROESY
Figure 3 NMR analyses of quadoctomycin. A full color version of this figure is available at The Journal of Antibiotics journal online.
simple signal, minor signals appeared gradually, giving complicated methyl-α-D-mannoside, for which NMR and optical rotation data
spectra as shown in Supplementary Figure S2. The reason is not clear, were in good agreement with those of an authentic sample (see
but this finding was also supported by LC-HRESI/MS, which gave Supplementary figure S13 to S16). Figure 1 shows the structure of
peaks of the same m/z with different retention times in an extracted quadoctomycin elucidated from all the results. The absolute stereo-
ion chromatogram (see, Supplementary Figure S3). Pyridine-d5 at chemistry of the aglycon of quadoctomycin is currently being studied.
5 °C was suitable for NMR analysis. Table 1 summarizes H and 13C
1
7
3
Quadoctomycin is structurally related to monazomycin A, dis-
1
3
8
NMR data for quadoctomycin. The C NMR and DEPT-135 spectra covered by Professor Hamao Umezawa et al. in 1963. NMR data for
revealed that quadoctomycin contains 76 carbon atoms, including 14 quadoctomycin were closely related to that for monazomycin A in
3
2
methyl-, 19 methylene-, 34 sp methine-, six sp methine-, two fully methanol-d , but the NMR assignment for monazomycin A has not
4
2
substituted sp - and one carbonyl-carbon(s).
The structure of quadoctomycin was determined by H- H COSY, in pyridine-d5 at 35 °C. The assignment of monazomycin A was
been published. We compared quadoctomycin and monazomycin A
1
1
1
1
HSQC-TOCSY and HMBC. H- H COSY showed correlations from established by analyzing 1D and 2D NMR spectra (not described in
isolated olefin, hydroxy methine or methyl signals to adjacent protons detail, see Supplementary Figure S17-22, Supplementary Table S1).
from H-7 to H-10-Me, H-11 to H-15, H-16-Me to H-19, H-20-Me to The differences in chemical shifts were around C-10, and from C-50
H-24-Me, H-25 to H-32-Me, H-37 to H-38-Me, H-39 to H-49 and to C-54 of the side chain, however the remaining H and C chemical
from H-50 to H-50-Me. Other correlations from characteristic hydroxy shifts of monazomycin A were almost the same as those for
methine signals from H-1’ to H-6’ suggested the presence of a sugar quadoctomycin. Thus, quadoctomycin was determined to be a novel
moiety. The HSQC-TOCSY spectra confirmed these connectivities and 48-membered ring macrolide having a methyl group at C-10 and a
other correlations from H-2 to H-8-Me, H-33 to H-37 and H-51 to different side chain length from C-47 of monazomycin A.
1
13
H-56, establishing the partial structures shown in bold in Figure 3. The
Actinomycetes are known to produce many macrolides. Among
connectivities of these partial structures were analyzed by HMBC. The them, the one with the largest ring structure is a 60-membered ring,
cross-peaks observed from H-10-Me to C-9-11, H-16-Me to C-15-17, quinolidomicin, reported by Hayakawa et al.9 As far as the authors
H-20-Me to C-19-C-21, H-21 to C-19, H-24-Me to C-23-25, H-32-Me know, quadoctomycin has the second largest ring structure (48-
,10
membered) equal to that of monazomycin A,7 B.
,8
11
to C31-33, H-38-Me to C-37-39, H-50-Me to C-49-51 and the
methylene proton of H-2 and the oxymethine of H-47 to C-1,
established a 48-membered macrolide skeleton. The sugar moiety
was established by the correlation from H-1’ to C-5’ and the moiety
was connected to C-22 by the cross-peaks between H-22/C-22 and
C-1’/H-1’ in the HMBC spectrum. The planar structure of quadocto-
mycin determined from these results as shown in Figure 3.
Biological activities
Quadoctomycin showed potent antibacterial activity against S. aureus
including methicillin-resistant S. aureus) with minimum inhibitory
(
− 1
concentrations (MICs) of 1–2 μg ml (Table 2). Quadoctomycin also
had antibacterial activity against other Gram-positive pathogenic
bacteria such as Enterococcus faecalis and E. faecium (including drug-
resistant strains), Micrococcus luteus, Bacillus subtilis, B. cereus, Myco-
bacterium smegmatis and Corynebacterium bovis, with minimum
Quadoctomycin has four double bonds and their geometries were
determined to be 12E, 16E, 20E and 28E from the large proton–proton
3
3
13
coupling constants ( J
= 15.4 Hz, JH28H29 = 15.4 Hz),
C
H12H13
chemical shifts (δC-16Me 13.1 p.p.m. and δC-20Me 13.4 p.p.m.) and
NOESY cross-peaks observed between H-15 and H-17, H-17 and
H-19 and H-19 and H-21.
− 1
inhibitory concentrations of 0.5–2 μg ml . Quadoctomycin did not
show antimicrobial activity toward Gram-negative bacteria or Candida
albicans (Table 2). Antimicrobial activities of quadoctomycin showed
equal or two to fourfold more potent than those of monazomycin A as
shown in Table 2.
The sugar moiety was determined to be α-mannoside by proton–
3
3
3
proton ( J
= 1.5 Hz, JH2’H3’ = 3.3 Hz, JH3’H4’ = 9.2 Hz and
H1’H2’
3
J
= 9.2 Hz) and direct carbon–proton coupling constants
JC1’H1’= 170.0 Hz) and NOESY observed between H-1’ and H-2’,
H4’H5’
1
(
MATERIALS AND METHODS
General
H-2’ and H-3’ and H-3’ and H-5’. The stereochemistry of the sugar
moiety was determined by the optical rotations of methanolysis
The optical rotations of compounds were obtained using a P-1030 polarimeter
product for quadoctomycin. Quadoctomycin (40 mg) was dissolved (JASCO, Tokyo, Japan). UV spectra were recorded with a U-2800 UV-Vis
in hydrogen chloride-methanol at 65 °C for 3 h, which gave 1.6 mg of spectrophotometer (Hitachi High-Technologies, Tokyo, Japan). IR spectra were
The Journal of Antibiotics

A new 48-membered macrolide, quadoctomycin
R Sawa et al
5
Table 2 Antimicrobial activities of quadoctomycin and monazomycin A
MIC (μg ml−1)
Test organisms
Quadoctomycin Monazomycin A
Test organisms
Quadoctomycin Monazomycin A
Staphylococcus aureus FDA 209P
Staphylococcus aureus Smith
1
2
2
4
4
4
4
4
8
1
1
1
4
4
4
2
8
4
8
4
Enterococcus
Enterococcus
Enterococcus
Escherichia
Escherichia
Escherichia
Escherichia
Escherichia
Escherichia
Shigella
faecium
faecium
faecium
coli
JCM 5804
NCTC12202
NCTC12204
NIHJ
2
2
4
8
1
Staphylococcus aureus MS9610
Staphylococcus aureus MRSA No.5
Staphylococcus aureus MRSA No.17
Staphylococcus aureus MS16526(MRSA)
Staphylococcus aureus TY-04282(MRSA)
Staphylococcus aureus Mu50
2
2
4
2
464
128
464
464
64
464
4128
464
32
2
coli
K-12
1
coli
K-12 ML1629
BEM11
2
coli
2
coli
BE1121
32
Micrococcus
Micrococcus
Micrococcus
Bacillus
luteus
luteus
luteus
FDA 16
0.5
0.5
0.5
2
coli
BE1186
64
32
IFO 3333
PCI 1001
dysenteriae JS11910
464
464
464
464
464
464
464
464
2
464
464
464
464
464
464
464
464
2
Salmonella
Proteus
enteritidis
vulgaris
1891
subtilis NRRL B-558
subtilis PCI 219
OX19
Bacillus
2
Proteus
mirabilis
IFM OM-9
Bacillus
subtilis ATCC23857 (168)
cereus ATCC 10702
2
Serratia
marcescens B-0524
aeruginosa A3
pneumoniae PCI 602
Bacillus
1
Pseudomonas
Klebsiella
Corynebacterium bovis
1810
2
Enterococcus
Enterococcus
Enterococcus
faecalis JCM 5803
faecalis NCTC12201
faecalis NCTC12203
1
Candida
albicans
3147
2
Mycobacterium smegmatis
ATCC607*
2
Agar dilution streak method (twofold dilution).
Medium & Culture condition: Mueller-Hinton agar (Difco) 37 °C 18 h., *37 °C 42 h. “DYNATEC”.
recorded with a FT/IR-4100 Fourier-transform infrared spectrometer (JASCO). into 14 K-1 flasks containing solid medium. The culture was incubated
1H and 13C NMR spectra, including 2D NMR, were measured with an statically at 30 °C for 14 days. The whole fermentation culture (560 g) was
ECZ600R spectrometer (JEOL Resonance, Tokyo, Japan) and an AVANCE III extracted with acetone (560 ml, twice) and the acetone extract obtained by
500 spectrometer (Bruker, Billerica, MA, USA) using solvent signals as an filtration. The solvent was concentrated in vacuo; water (300 ml) was added and
internal reference. Mass spectra were recorded using a LTQ Orbitrap XL mass extracted with an equivalent volume of n-BuOH. The organic layer was
spectrometer (Thermo Fisher Scientific, San Jose, CA, USA). The novelty of evaporated and partitioned by n-hexane/MeOH (10 ml each). The MeOH layer
quadoctomycin was searched using the Dictionary of Natural Products on DVD was concentrated to dryness to obtain a brown solid (1 g). The residue was
databases (Chapman & Hall/CRC Press, Boca Raton, FL, USA) and SciFinder suspended in a small amount of chloroform/MeOH (1:1) and applied to a silica
(Chemical Abstracts Service, Columbus, OH, USA). Standard methyl-α-D-
gel column (50 g, Silica gel 60 Art 1.07734; Merck KGaA, Darmstadt, Germany)
mannoside was purchased from Sigma Aldrich, St Louis, MO, USA. Mon- and washed with chloroform/MeOH/H O (v/v 3:1:0.15) and eluted with
2
azomycin A was obtained from our inhouse library.
chloroform/MeOH/H O (v/v 10:5:1) to give 339 mg of light-brown solid.
2
The solid containing the quadoctomycin was further purified by HPLC (600E
Taxonomic studies of the producing strain MM168-141F8
System, Waters, Milford, MA, USA) using an ODS column (Shiseido, Capcell
Morphological properties were observed following incubation at 30°C for Pak UG120, 30 mm id× 250 mm; Tokyo, Japan) developed with 35%
1 days on yeast extract-malt extract agar (ISP medium No. 2), oatmeal agar acetonitrile aqueous solution containing 0.01% trifluoroacetic acid to give 55
2
28
(
ISP medium No. 3) and inorganic salt starch agar (ISP medium No. 4). mg of quadoctomycin: white powder; [α]D +15° (c 0.5, MeOH); IR νmax
−
1
Detailed observation of mycelial morphology was performed using a scanning (KBr) cm 3406, 2965, 2934, 1780, 1677, 1458, 1434, 1385, 1092, 1070, 1049,
1
13
electron microscope (SU-1510, Hitachi High-Technologies) after strain 974; UV λmax (MeOH) end absorption; H NMR (pyridine-d5, 600 MHz),
C
MM168-141F8 was incubated on ISP medium No. 3 at 30 °C for 8 days. NMR (pyridine-d5, 150 MHz) data are given in Table 1; HRESI/MS [M+H]+
The type of diaminopimelic acid isomers in whole-cell hydrolysates was
determined by the method of Staneck and Roberts.12 The total DNA of
m/z 1436.9961 (calcd. for C76H142NO23, 1436.9967).
MM168-141F8 was prepared using a Genomic DNA Extraction Kit Mini (RBC Methanolysis of quadoctomycin
Bioscience Co., New Taipei, Taiwan) according to the manufacturer’s instruc- Quadoctomycin (40 mg) was dissolved in 3 M hydrogen chloride-MeOH and
13
tions. 16S rRNA (positions 56–1495, Escherichia coli numbering system ) was stirred at 65 °C for 3 h. The solution was concentrated in vacuo. The residue
amplified by PCR and sequenced. A search for the most closely related was dissolved in a small amount of MeOH and applied to Sephadex LH-20 (GE
sequences was performed using the EZ Taxon database (http://www.ezbiocloud. Healthcare Bio-Sciences, Uppsala, Sweden). The fractions containing
net/).14
methyl glycoside were collected and dried. The residue was subjected to
hydrophilic interaction liquid chromatography (XBridge Amide, 3.5 μm,
10 mm id× 150 mm, Waters, 90–50% acetonitrile, three times). The pure
Fermentation and purification of quadoctomycin
A slant culture of Streptomyces sp. MM168-141F8 was inoculated into a 500-ml fraction containing methyl glycoside was collected and concentrated to dryness
28
baffled Erlenmeyer flask containing 110 ml of a seed medium consisting of to give 1.6 mg of methyl-α-mannoside: colorless solid; [α]D +71° (c 0.1,
1
2
.0% galactose, 2.0% dextrin, 1.0% Bacto Soytone (Becton Dickinson and H2O); H NMR (D2O, 500 MHz) δ 4.74 (1H, d, 1.7, H-1), 3.91 (1H, dd, 3.4,
Company, Franklin Lakes, NJ, USA), 0.5% corn steep liquor (Kogo Starch, 1.7, H-2), 3.88 (1H, dd 12.3, 2.0, H-6b), 3.73 (1H, dd, 12.3, 5.7, H-6a), 3.73
Chiba, Japan), 0.2% (NH ) SO and 0.2% CaCO , pH 7.4 before sterilization. (1H, m, H-3), 3.62 (1H, t 9.7, H-4), 3.59 (1H, m, H-5), 3.39 (3H, s, H-1OMe);
4
2
4
3
13
The culture was incubated at 27 °C for 3 days on a rotary shaker at 180 rpm.
Production was performed using a solid medium (15 g of pressed barley and (d, C-2), 69.4 (d, C-4), 63.6 (t, C-6), 57.4 (q, C-1OMe); HRESI/MS [M+Na]+
5 ml of deionized water). Portions of 7 ml of this seed culture were inoculated m/z 217.0685 (calcd for C H O Na, 217.0683).
C NMR (D2O, 125 MHz) δ 103.5 (d, C-1), 75.2 (d, C-5), 73.2 (d, C-3), 72.6
2
7
14 6
The Journal of Antibiotics

A new 48-membered macrolide, quadoctomycin
R Sawa et al
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Antimicrobial activity
3
4
5
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DEDICATION
(
This article is dedicated to Professor Dr. Hamao Umezawa in honor of
his profound contributions to basic science and the improvement of
human health.
7
8
(1963).
9
Hayakawa, Y., Shinya, K., Furihata, K. & Seto, H. Structure of a novel 60-membered
macrolide, quinolidomicin A1. J. Am. Chem. Soc. 115, 3014–3015 (1993).
CONFLICT OF INTEREST
The authors declare no conflict of interest.
10 Hayakawa, Y., Shinya, K., Furihata, K. & Seto, H. Quinolidomicins A1, A2 and B1,
novel 60-membered macrolide antibiotics. II. Structure elucidation. J. Antibiot. 46,
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actinomycetes by thin-layer chromatography. Appl. Microbiol. 28, 226–231
1974).
ACKNOWLEDGEMENTS
1
1
a
new macrolide antibiotic of the
We thank Dr K Furihata, University of Tokyo, for providing NMR spectra of
monazomycin A. We thank Ms N Kinoshita, Ms R Arisaka and Ms Y Shibuya,
Institute of Microbial Chemistry (BIKAKEN), Tokyo for providing technical
assistance.
&
(
1
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Supplementary Information accompanies the paper on The Journal of Antibiotics website (http://www.nature.com/ja)
The Journal of Antibiotics