Article Cite This: J. Nat. Prod. XXXX, XXX, XXX−XXX
pubs.acs.org/jnp
Pentaminomycins A and B, Hydroxyarginine-Containing Cyclic Pentapeptides from Streptomyces sp. RK88-1441 Jun-Pil Jang,†,∥ Gwi Ja Hwang,†,§,∥ Min Cheol Kwon,†,§ In-Ja Ryoo,† Mina Jang,†,§ Shunji Takahashi,⊥ Sung-Kyun Ko,†,§ Hiroyuki Osada,*,‡ Jae-Hyuk Jang,*,†,§ and Jong Seog Ahn*,†,§ †
Anticancer Agent Research Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju 28116, Korea Chemical Biology Research Group, RIKEN Center for Sustainable Research Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan § Department of Biomolecular Science, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon 34141, Korea ⊥ RIKEN-KRIBB Joint Research Unit, RIKEN CSRS, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan ‡
S Supporting Information *
ABSTRACT: Two new cyclic peptides, pentaminomycins A (1) and B (2), were isolated from cultures of Streptomyces sp. RK88-1441. Based on the interpretation of the NMR, UV, IR, and MS data, the planar structures of 1 and 2 were elucidated as cyclic pentapeptides with a modified amino acid residue, N5-hydroxyarginine (N5-OH-Arg). The absolute configurations of the constituent amino acid residues were determined by the advanced Marfey’s method. Localization of L- and D-amino acids in the sequence was ascertained by chiral analysis of the fragment peptide obtained from a partial hydrolysate; amino acids were identified by LC-MS. Pentaminomycin A (1) reduced α-MSH-stimulated melanin synthesis by suppressing the expression of melanogenic enzymes including tyrosinase, tyrosinase-related protein-1 (TRP-1), and tyrosinase-related protein-2 (TRP-2).
M
derivative were previously unreported. These compounds were identified as two new cyclic peptides, pentaminomycins A (1) and B (2), that contain a modified amino acid residue, N5hydroxyarginine (N5-OH-Arg). The isolation, structure elucidation, and biological activity of these two new peptides are described below.
icrobial secondary metabolites have provided many chemical templates for clinically useful lead compounds in the pharmaceutical industry.1,2 Secondary metabolites from actinomycetes in particular have generated significant interest, as many have unique structural features and interesting biological properties.3,4 A number of them are used as probes to investigate biological functions.5 However, the isolation of novel compounds has become more difficult, and traditional approaches typically lead to known compounds.6 To overcome this, we have focused our attention on discovering novel secondary metabolites from actinomycetes cultured using different growth media and studied their chemical profiles by PDA-LC/MS. We recently reported the isolation and structure elucidation of a new benadrostin derivative named RK-144171, together with two other known compounds, 3-indolylcarbonyl α-L-rhamnopyranoside and 2-aminobenzoyl α-L-rhamnopyranoside from the fermentation broth of Streptomyces sp. RK881441.7 Further chemical analysis using PDA-LC/MS identified a Streptomyces strain (RK88-1441) that produces a major metabolite ([M + H]+ m/z at 670) (Figure S11) with an indole moiety (UV λmax 210 and 280 nm).8 Initial dereplication based on the UV and MS data indicated that this compound and its © XXXX American Chemical Society and American Society of Pharmacognosy
Received: October 23, 2017
A
DOI: 10.1021/acs.jnatprod.7b00882 J. Nat. Prod. XXXX, XXX, XXX−XXX
Journal of Natural Products
Article
Table 1. 1H (800 MHz) and 13C (200 MHz) NMR Data for Pentaminomycins A (1) and B (2) in DMSO-d6 pentaminomycin A (1) δC
position Val-1
Val-2
Trp
N5OH-Arg
Leu
a
1 2 3 4 5 NH
171.3, C 57.6, CH 30.3, CH 19.0, CH3 18.4, CH3
1 2 3 4 5 NH 1 2 3
171.3, C 59.9, CH 28.3, CH 19.1, CH3 18.5, CH3 171.5, C 55.3, CH 26.9, CH2
2-NH 1′(NH) 2′ 3′ 3′a 4′ 5′ 6′ 7′ 7′a 1 2 3
123.9, CH 110.2, C 126.8, C 117.8, CH 118.2, CH 120.7, CH 111.2, CH 136.1, C 170.5, C 52.6, CH 28.4, CH2
4
22.2, CH2
5 6 NH 1 2 3 4 5 6 NH
50.3, CH2 158.1, C
pentaminomycin B (2) δH, mult. (J in Hz) Leu-1 4.09, 1.81, 0.83, 0.82, 7.66,
dd (8.5, 6.9) m d (7.3) d (7.1) d (7.2)
3.74, 1.64, 0.77, 0.33, 8.36,
dd (8.5, 7.7) ma d (6.5) d (6.5) d (6.3)
Val
Trp 4.28, m 3.20, dd (14.2, 2.7) 2.94, dd (11.9, 8.2) 8.71, d (7.0) 10.80, s 7.17, s
7.52, 6.98, 7.04, 7.30,
d (7.8) t (7.3) t (7.4) d (8.0) N5OH-Arg
4.24, dd (14.0, 7.1) 1.62, ma 1.52, ma 1.46, ma 3.50, t (7.1) 7.24, d (4.9)
171.0, C 50.3, CH 36.9, CH2 24.1, CH 22.5, CH3 21.8, CH3
Leu-2 4.33, 1.48, 1.54, 0.88, 0.81, 8.73,
δC
position
dd (15.1, 7.6) ma ma d (6.5) d (7.1) d (7.4)
1 2 3 4 5 6 NH 1 2 3 4 5 NH 1 2 3
172.0, C 50.3, CH 40.7, CH2 24.3, CH 22.6, CH3 22.0, CH3 171.2, C 59.6, CH 28.7, CH 19.0, CH3 18.5, CH3 171.6, C 55.4, CH 26.9, CH2
2-NH 1′(NH) 2′ 3′ 3′a 4′ 5′ 6′ 7′ 7′a 1 2 3
123.9, CH 110.1, C 126.8, C 117.9, CH 118.2, CH 120.7, CH 111.3, CH 136.1, C 170.6, C 52.4, CH 28.4, CH2
4
22.3, CH2
5 6 NH 1 2 3 4 5 6 NH
50.4, CH2 158.1, C
δH, mult. (J in Hz) 4.40, 1.38, 1.52, 0.87, 0.84, 7.77,
dd (15.8, 7.9) m ma d (6.3) d (6.4) d (7.2)
3.76, 1.64, 0.74, 0.36, 8.30,
dd (8.5, 5.3) ma d (6.3) d (6.4) d (5.4)
4.28, ma 3.18, ma 2.95, dd (16.0, 12.6) 8.74, d (7.0) 10.82, s 7.16, s
7.52, 6.98, 7.04, 7.30,
d (7.7) t (7.8) t (7.3) d (7.9)
4.24, 1.65, 1.60, 1.53, 1.46, 3.49,
dd (14.0, 7.1) ma ma ma ma ma
7.35, d (5.6) 171.0, C 50.6, CH 37.3, CH2 24.2, CH 22.6, CH3 22.0, CH3
4.29, 1.46, 1.52, 0.87, 0.84, 8.55,
ma ma ma d (6.3) d (6.4) d (6.0)
Resonances overlapped.
■
spectrum (DMSO-d6) exhibited five exchangeable amide NH signals (δH 7.0−9.0), five amino acid α-proton signals (δH 3.0− 5.0), five aromatic signals (δH 6.0−8.0), and 16 aliphatic methine, methylene, and methyl signals (δH 0.0−3.0) (Table 1). The 13C NMR spectrum for 1 exhibited five distinguishable signals for amide-type carbonyls (δC 170.5−171.5), indicating the peptidic nature of 1. Combined analysis of the COSY, TOCSY, and HMBC NMR data identified that 1 was composed of five amino acids: two valines (Val), tryptophan (Trp), N5-hydroxyarginine (N5-OH-Arg), and leucine (Leu) (Figure 1). In particular, the presence of the hydroxy group at N-5 of the guanidino group was suggested by the downfield shift of the nitrogen-bound C-5 (δC 50.3) (Table 1)9 and by the further HMBC correlation from H-5 (δH 3.50) to C-6 (δC
RESULTS AND DISCUSSION Streptomyces sp. RK88-1441 was cultured in modified CDY media for 8 days at 28 °C, and the broth and mycelia extracts were partitioned with EtOAc. The EtOAc extracts were purified by ODS vacuum flash chromatography and reversed-phase HPLC to yield pentaminomycins A (1) and B (2). Pentaminomycin A (1) was isolated as a brown amorphous powder. The molecular formula of 1 was established as C33H51N9O6 on the basis of HRESIMS data and NMR analyses, including 13 degrees of unsaturation. The IR spectrum suggested the presence of amine (3269 cm−1) and amidetype carbonyl (1629 cm−1) functionalities, and the UV spectrum indicated that 1 was a peptide with an indole residue with absorption bands at 210 and 280 nm. The 1H NMR B
DOI: 10.1021/acs.jnatprod.7b00882 J. Nat. Prod. XXXX, XXX, XXX−XXX
Journal of Natural Products
Article
was ascertained by partial hydrolysis.12,13 To obtain a suitable fragment, compound 1 was subject to various hydrolysis conditions, and the partial hydrolysate of 1 was analyzed by LC-MS. One peptide that contained the Leu-Val-1 residue was purified by HPLC. The absolute configuration of the Leu-Val-1 residue was determined as D-Leu and L-Val-1 by complete hydrolysis and advanced Marfey’s analysis (Figure S10). Therefore, the structure of compound 1 was assigned as cyclo-(L-Val-D-Val-L-Trp-N5-OH-L-Arg-D-Leu) and named pentaminomycin A. Pentaminomycin B (2) was obtained as a brown amorphous powder. The molecular formula was established as C34H53N9O6 based on HRESIMS and NMR analyses. The molecular formula showed the appearance of an additional methylene group, compared to compound 1, which indicates that 2 is an analogue of 1 with slight modifications. The 1H and 13C NMR data of 2 were similar to those of 1; however, new signals corresponding to a methylene group (δC 40.7/δH 1.38) were observed. The combined analysis of the COSY, HSQC-TOCSY, and HMBC NMR data showed that 2 was composed of five amino acids, including valine (Val), tryptophan (Trp), N5-hydroxy arginine (5-OH-Arg), leucine (Leu-1), and an additional leucine (Leu2) not observed in 1 (Figure 1). Therefore, we hypothesized that one of the Val residues of 1 was replaced with Leu. The amino acid sequence was also established by the combined analysis of the HMBC and ROESY data (Figure 1). The absolute configurations of the amino acid residues comprising cyclopeptide 2 were determined by the advanced Marfey’s method. The absolute configurations of the amino acids were DLeu, L-Leu, and D-Val, and the hydroxy group of N5-OH-Arg was removed under acidic conditions and the configuration determined as L (Table S2). The Marfey’s agent derivatized Trp was not detected, although compound 2 was hydrolyzed in 6 N HCl at 100 °C for shorter times to prevent degradation. Using thioglycolic acid in the hydrolysis procedure,14,15 however, facilitated the absolute configuration of Trp to be determined as L. Compound 2 is very similar to compound 1 except for one additional Leu residue. Furthermore, similar physical data and overall chemical shifts of 2 with those of 1 revealed that they share the same macrocyclic scaffold. Thus, compounds 1 and 2 most probably share a related biosynthetic origin. The structure of 2 was determined to be cyclo-(L-Leu-D-Val-L-Trp-N5-OH-LArg-D-Leu) and named pentaminomycin B (2). Pentaminomycins A (1) and B (2) showed no significant cytotoxicity at a concentration of 30 μM against human cervical cancer cells (HeLa), mouse mammary gland carcinoma cells (4T1), and mouse melanoma cells (B16F0 and B16F10). They were also evaluated for an antimelanogenic activity against alpha-melanocyte stimulating hormone (α-MSH)-stimulated B16F10 melanoma cells. Pentaminomycin A (1) effectively reduced α-MSH-stimulated melanin synthesis by suppressing the expression of melanogenic enzymes including tyrosinase, tyrosinase-related protein-1 (TRP-1), and tyrosinase-related protein-2 (TRP-2) (Figures 3 and 4). Previous cyclic pentapeptides isolated from microorganism, such as malformin A1, malformin C, malformin E, cyclo-(L-Ile-L-Leu-L-Leu-L-LeuL-Leu), lajollamide A, and aspergillipeptide D, were reported to exhibit cytotoxicity, as well as antimicrobial and antiviral activities.16−21 In this paper, we evaluated their antimelanogenesis effect for the first time.
Figure 1. Key 2D NMR correlations of pentaminomycins A (1) and B (2).
158.1) (Figure 1). The assignment of the amino acid sequence was determined by analysis of HMBC, ROESY (Figure 1), and MS/MS data (Figure 2; see also the Supporting Information,
Figure 2. MS/MS fragmentation pattern of pentaminomycin A (1). The dashed lines through the structures indicate the “y” and “b” fragments, and the described numbers indicate the corresponding m/z value (n.d.: not detected).
Figure S9). The HMBC correlations from Val-2 H-2 (δH 3.74) to Val-1 C-1 (δC 171.3), from Val-1 H-2 (δH 4.09) to Leu C-1 (δC 171.0), from Leu H-2 (δH 4.33) to N5-OH-Arg C-1 (δC 170.5), and from N5-OH-Arg H-2 (δH 4.24) to Trp C-1 (δC 171.5) suggested an amino acid sequence of Val-2-Val-1-LeuN5-OH-Arg-Trp. A ROESY correlation between Trp NH (δH 8.71) and Val-2 H-2 (δH 3.74) and the molecular formula indicated that 1 must be cyclic. The amino acid sequence, in particular N5-OH-Arg of 1, was further confirmed by a detailed analysis of the MS/MS data (Figure 2). Consequently, the planar structure of 1 was elucidated as a cyclic pentapeptide with a sequence cyclo-(Val-1-Val-2-Trp-N5-OH-Arg-Leu) (Figure 1). The absolute configurations of the amino acids were determined by advanced Marfey’s analysis. Compound 1 was hydrolyzed in 6 N HCl at 100 °C for 4 h and derivatized using L- and D-FDLA (L- and D-1-fluoro-2,4-dinitrophenyl-5-leucineamide) followed by LC-MS analysis.10,11 The results clarified that the absolute configurations of the amino acid residues were D-Leu, D-Val, and L-Val (Table S1). Furthermore, the hydroxy group of N5-OH-Arg was removed under acidic conditions and the configuration was determined as L. Using milder hydrolysis conditions followed by advanced Marfey’s derivatization showed the absolute configuration of Trp was L. The localization of the L-Val and D-Val amino acids in the sequence C
DOI: 10.1021/acs.jnatprod.7b00882 J. Nat. Prod. XXXX, XXX, XXX−XXX
Journal of Natural Products
Article
Strain Identification. A soil sample was collected at Komagome, Tokyo, Japan. The strain RK88-1441 was isolated by a conventional method.22,23 The strain showed the highest 16S rRNA gene sequence (GenBank accession number: MG241290) similarities to Streptomyces atratus NBRC 3897 (100%, 1361/1361), Streptomyces sanglieri NBRC 100784 (99%, 1360/1361), and Streptomyces pulveraceus NBRC 3855 (99%, 1357/1361). Therefore, the strain RK88-1441 was identified and named Streptomyces sp. RK88-1441. The strain was stored at the RIKEN Center for Sustainable Research Science.23 Culture Conditions. Streptomyces sp. RK88-1441 was cultured in a 250 mL Erlenmeyer flask containing 50 mL of seed culture medium (soluble starch 1%, yeast extract 0.1%, and tryptone 0.1%) for 3 days at 28 °C on a rotary shaker with agitation at 125 rpm. For a large culture, 1% of the preculture broth was inoculated into 40 × 1000 mL baffled Erlenmeyer flasks containing 250 mL of modified CDY broth (glucose 2%, soluble starch 1%, meat extract 0.3%, yeast extract 0.25%, K2HPO4 0.005%, NaCl 0.05%, CaCO3 0.05%, and MgSO4·7H2O 0.05%), which were cultured for 8 days at 28 °C on a rotary shaker with agitation at 125 rpm. Extraction and Isolation. About 10 L of fermentation culture was partitioned with EtOAc three times and evaporated to remove EtOAc. The crude extract (2.5 g) was fractionated by reversed-phase C18 vacuum column chromatography with a stepwise solvent system of MeOH−H2O (20:80 to 100:0, each X 1 L) to yield nine frractions. The fraction eluted with MeOH−H2O (70:30, 43.4 mg) was further purified by reversed-phase HPLC (Cosmosil semipreparative C18, 30% CH3CN, 3 mL/min, UV detection at 210, 280 nm) to obtain pentaminomycins A (1, 6.5 mg, tR 14.9 min) and B (2, 1.5 mg, tR 17.5 min). Pentaminomycin A (1): brown, amorphous powder; [α]25 D −23.1 (c 0.1, MeOH); UV (MeOH) λmax (log ε) 220 (3.60), 285 (2.35); IR (ATR) νmax 3269, 2923, 2857, 1629, 1544, 1457, 1350 1223 cm−1; 1H and 13C NMR data, Table 1; HRESIMS m/z 670.4034 [M + H]+ (calcd for C33H52N9O6, 670.4041). Pentaminomycin B (2): brown, amorphous powder; [α]25 D −9.1 (c 0.1, MeOH); UV (MeOH) λmax (log ε) 220 (3.14), 285 (3.78); IR (ATR) νmax 3267, 2923, 2857, 1628, 1590, 1457, 1353 cm−1; 1H and 13 C NMR data, Table 1; HRESIMS m/z 684.4191 [M + H]+ (calcd for C34H54N9O6, 684.4197). LC-MS Analysis of the FDLA Derivatives of the Amino Acids. Compound 1 (0.4 mg) was hydrolyzed in 6 N HCl (500 μL) at 100 °C for 1 h. Compound 2 was hydrolyzed in 6 N HCl (500 μL) containing 1% thioglycollic acid at 100 °C for 30 min. After cooling to room temperature, the solvent was removed under vacuum. The remaining hydrolysate was resuspended in 200 μL of H2O and separated into two portions. The residue was dried, then dissolved in 50 μL of 1 N NaHCO3 and treated with 50 μL of either 1% (w/v) Lor D-FDLA (L- or D-1-fluoro-2,4-dinitrophenyl-5-leucineamide) in acetone. The mixture was heated at 40 °C for 1 h. After cooling to room temperature, the contents were neutralized with 10 μL of 2 N HCl, and the resulting mixture was added to 50 μL of MeOH to afford a final hydrolysate volume of 100 μL. The solution was then analyzed by LC-MS selected ion chromatography on a reversed-phase column (2.1 × 150 mm, 2.5 μm; Waters, Milford, MA, USA) with a linear gradient from 5% to 100% aqueous CH3CN containing formic acid over 15 min (0.3 mL/min). A Trp standard was prepared in the same manner, and mixtures were then processed for LC-MS to compare the retention times of the reaction products. (Retention time for L- and DFDLA derivatives: 12.97, 13.66 min). The retention times for the Land D-FDLA derivatives of compound 1 (min) were as follows: Val-1 and -2 12.49, 13.95, 13.95, and 12.49; Trp 12.95 and 13.65; Arg 9.75 and 9.43; Leu 14.72 and 13.06. The retention times for the L- and DFDLA derivatives of compound 2 (min) were as follows: Leu-1 and-2 13.06, 14.72, 14.72, and 13.06; Val 13.95 and 12.48; Trp 12.97 and 13.64; Arg 9.75 and 9.43. LC-MS-Guided Fractionation of the Partial Hydrolysate. Compound 1 (1 mg) was hydrolyzed in 4 N HCl (200 μL) at 100 °C for 7 h. The hydrolysis was stopped by diluting with 3 volumes of cold H2O (600 μL) and stored at −20 °C prior to the analysis. The remaining hydrolysate was resuspended in 100 μL of MeOH and then
Figure 3. Inhibitory effects of compound 1 (μM) on B16F10 mouse melanoma cells. B16F10 cells were treated with various concentrations of compound 1 for 24 h at 37 °C with or without α-MSH (alphamelanocyte-stimulating hormone). Each value is expressed as the mean ± SD (n = 3, **: p > 0.05).
Figure 4. Inhibitory effects of compound 1 (μM) on the levels of tyrosinase, TRP-1, and TRP-2 in α-MSH-induced B16F10 cells. B16F10 cells (1.0 × 105 cells/mL) were preincubated for 24 h, and then, the cells were stimulated with α-MSH (100 nM) and various concentrations (5, 7.5, and 10 μM) of compound 1 for 24 h. The expression level was determined using immunoblotting methods.
■
EXPERIMENTAL SECTION
General Experimental Procedures. Optical rotations were obtained with a JASCO P-1020 polarimeter (JASCO, Japan). UV spectra were recorded on an Optizen 2120 UV spectrophotometer (Mecasys, Korea). IR spectra were recorded on a Bruker VERTEX80 V FT-IR spectrometer (Bruker, Germany). NMR experiments were performed using a Bruker AVANCE HD 800 MHz NMR spectrometer (Bruker, Germany) at the Korea Basic Science Institute (KBSI) in Ochang, Korea. NMR spectra were recorded in DMSO-d6 as an internal standard (δH 2.49/δC 39.5). High-resolution electrospray ionization mass spectra (HRESIMS) were recorded on a Waters Synapt G2 mass spectrometer (Waters, USA) at the KBSI in Ochang, Korea. Column chromatography was performed on reversed-phase silica gel (0.075 mm; Cosmosil, Japan). Analytical C18 (Cosmosil, 5 μm, 4.6 × 150 mm) and semipreparative C18 (Cosmosil, 10 μm, 10 × 250 mm) columns were used for reversed-phase HPLC on a YL900 HPLC system (Young Lin, Korea) equipped with a YL9120 UV/vis detector (Young Lin, Korea) that used HPLC grade solvents (Burdick & Jackson, USA). A liquid chromatography−mass spectrometry (LCMS) system was operated with an LTQ XL linear ion trap (Thermo Scientific, Rockford, IL, USA) equipped with an electrospray ionization (ESI) source that was coupled to a rapid separation LC (RSLC; Ultimate 3000, Thermo Scientific) system (ESI-LC-MS). D
DOI: 10.1021/acs.jnatprod.7b00882 J. Nat. Prod. XXXX, XXX, XXX−XXX
Journal of Natural Products
Article
analyzed by LC-MS to check the fragmentation pattern. Individual peaks were collected by linear gradient C18 HPLC (Cosmosil, 10 μm, 10 × 250 mm) from 10% to 50% CH3CN in H2O (0.05% formic acid) over 40 min (3 mL/min) and then were hydrolyzed and derivatized by Marfey’s reagent and analyzed in a similar manner. The L- and D-FDLA derivatives of Val including the partial hydrolysis fragment were eluted at 12.48 and 13.95 min. Cell Viability Test. The 4T1, HeLa, B16F0, and B16F10 cell lines were seeded in 96-well plates (5.0 × 104 cells/100 μL/well) and incubated for 24 h. After incubation with various concentrations (0− 10 μM) of pentaminomycins A and B for 24 h, the cells were then washed with phosphate-buffered saline (PBS). After a 2 h incubation with 100 μL of Dulbecco’s modified Eagle’s medium (DMEM) and 10 μL of EZ-Cytox solution (DoGen, Korea), the optical density of the water-soluble formazan produced by the living cells was measured with a microplate reader (SpectraMax 190, Molecular Devices) at 450 nm. Measurement of Extracellular Melanin Content. The B16F10 cells (3.5 × 104) were cultured in six-well plates with complete DMEM without phenol red at 37 °C in an atmosphere of 5% CO2 for 24 h. After 24 h, the cells were then treated with α-MSH (200 nM) and various concentrations (0−10 μM) of pentaminomycins A and B for 24 h. The cells were washed with PBS, and the cells were detached by incubation with trypsin−EDTA and centrifuged at 3000 rpm for 5 min. To determine the melanin content, the absorbance was measured at 405 nm using a microplate reader (SpectraMax 190, Molecular Devices).24,25 Western Blot Analysis. The B16F10 melanoma cells were incubated with various concentrations (0, 5, 7.5, and 10 μM) of pentaminomycins A and B for 24 h. Following incubation, the treated and untreated cells were lysed in M-per buffer (Thermo Scientific, USA), and whole cell protein was extracted and subjected to electrophoresis in SDS-PAGE and blotted onto nitrocellulose membranes. The membrane was probed with antibodies against tyrosinase, TRP-1, and TRP-2 (Abcam, USA). The bands were detected using Super Signal West Pico chemiluminescent substrate (Pierce, Rockford, IL, USA). Images of the blotted membranes were exposed to BioMax Light film (Kodak, USA).25
■
of Science & Technology), the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP; Ministry of Science, ICT & Future Planning) (NRF2017R1C1B2002602), and the KRIBB Research Initiative Program funded by the Ministry of Science ICT (MSIT) of the Republic of Korea. This study was also supported in part by Grants-in-Aid from the Ministry of Education, Culture, Sports, Science, and Technology of Japan and the Science and Technology Research Promotion Program for Agriculture, Forestry, Fisheries, and Food Industry. We thank the Korea Basic Science Institute, Ochang, Korea, for providing the NMR (800 MHz) and HR-ESIMS.
■
ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jnatprod.7b00882. 1D and 2D NMR, HR-ESIMS, and LC-MS results from the Marfey’s analysis of compounds 1 and 2 (PDF)
■
AUTHOR INFORMATION
Corresponding Authors
*(H. Osada) Tel: +81-48-467-9541. Fax: +81-48-462-4669. Email:
[email protected]. *(J.-H. Jang) Tel: +82-43-240-6164. Fax: +82-43-240-6169. Email:
[email protected]. *(J. S. Ahn) Tel: +82-43-240-6160. Fax: +82-43-240-6169. Email:
[email protected]. ORCID
Hiroyuki Osada: 0000-0002-3606-4925 Jae-Hyuk Jang: 0000-0002-4363-4252 Author Contributions ∥
REFERENCES
(1) Cragg, G. M.; Newman, D. J. J. Nat. Prod. 2016, 79, 629−661. (2) Butler, M. S.; Robertson, A. A.; Cooper, M. A. Nat. Prod. Rep. 2014, 31, 1612−1661. (3) Bérdy, J. J. Antibiot. 2015, 58, 1−26. (4) Genilloud, O.; González, I.; Salazar, O.; Martín, J.; Tormo, J. R.; Vicente, F. J. Ind. Microbiol. Biotechnol. 2011, 38, 375−389. (5) Nett, M.; Ikeda, H.; Moore, B. S. Nat. Prod. Rep. 2009, 26, 1362− 1384. (6) Monciardini, P.; Iorio, M.; Maffioli, S.; Sosio, M.; Donadio, S. Microb. Biotechnol. 2014, 7, 209−220. (7) Jang, J.-P.; Takahashi, S.; Futamura, Y.; Nogawa, T.; Jang, J.-H.; Ahn, J. S.; Osada, H. J. Antibiot. 2017, 70, 102−104. (8) Um, S.; Choi, T. J.; Kim, H.; Kim, B. Y.; Kim, S. H.; Lee, S. K.; Oh, K. B.; Shin, J.; Oh, D. C. J. Org. Chem. 2013, 78, 12321−12329. (9) Nemoto, A.; Hoshino, Y.; Katsukiyo, K.; Ando, A.; Mikami, Y. J. Antibiot. 2002, 55, 593−597. (10) Harada, K.; Fujii, K.; Hayashi, K.; Suzuki, M. Tetrahedron Lett. 1996, 37, 3001−3004. (11) Fujii, K.; Ikai, Y.; Oka, H.; Suzuki, M.; Harada, K. Anal. Chem. 1997, 69, 5146−5151. (12) Takada, K.; Ninomiya, A.; Naruse, M.; Sun, Y.; Miyazaki, M.; Nogi, Y.; Okada, S.; Matsunaga, S. J. Org. Chem. 2013, 78, 6746−6750. (13) Teta, R.; Marteinsson, V. T.; Longeon, A.; Klonowski, A. M.; Groben, R.; Bourguet-Kondracki, M. L.; Costantino, V.; Mangoni, A. J. Nat. Prod. 2017, 80, 2530. (14) Gerard, J. M.; Haden, P.; Kelly, M. T.; Andersen, R. J. J. Nat. Prod. 1999, 62, 80−85. (15) Grundmann, F.; Kaiser, M.; Kurz, M.; Schiell, M.; Batzer, A.; Bode, H. B. RSC Adv. 2013, 3, 22072−22077. (16) Li, X. B.; Xie, F.; Liu, S. S.; Li, Y.; Zhou, J. C.; Liu, Y. Q.; Yuan, H. Q.; Lou, H. X. Chem. Biodiversity 2013, 10, 1193−1201. (17) Wang, J.; Jiang, Z.; Lam, W.; Gullen, E. A.; Yu, Z.; Wei, Y.; Wang, L.; Zeiss, C.; Beck, A.; Cheng, E. C.; Wu, C.; Cheng, Y. C.; Zhang, Y. PLoS One 2015, 10, e0140069. (18) Ma, Y. M.; Liang, X. A.; Zhang, H. C.; Liu, R. J. J. Agric. Food Chem. 2016, 64, 3789−3793. (19) Talontsi, F. M.; Facey, P.; Tatong, M. D.; Tofazzal Islam, M.; Frauendorf, H.; Draeger, S.; Tiedemann, Av.; Laatsch, H. Phytochemistry 2012, 83, 87−94. (20) Gulder, T. A.; Hong, H.; Correa, J.; Egereva, E.; Wiese, J.; Imhoff, J. F.; Gross, H. Mar. Drugs 2012, 10, 2912−2935. (21) Ma, X.; Nong, X. H.; Ren, Z.; Wang, J.; Liang, X.; Wang, L.; Qi, S. H. Tetrahedron Lett. 2017, 58, 1151−1155. (22) Shirling, E. B.; Gottlieb, D. Int. J. Syst. Bacteriol. 1966, 16, 313− 340. (23) Osada, H.; Uramoto, M.; Uzawa, J.; Kajikawa, K.; Isono, K. Agric. Biol. Chem. 1990, 54, 2883−2887. (24) Matsumoto, T.; Nakamura, S.; Nakashima, S.; Fujimoto, K.; Yoshikawa, M.; Ohta, T.; Ogawa, K.; Matsuda, H. J. Nat. Prod. 2014, 77, 990−999. (25) Ali, A.; Ashraf, Z.; Kumar, N.; Rafiq, M.; Jabeen, F.; Park, J. H.; Choi, K. H.; Lee, S.; Seo, S. Y.; Choi, E. H.; Attri, P. Sci. Rep. 2016, 6, 21779−21800.
J.-P. Jang and G. J. Hwang contributed equally to this work.
Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS This work was supported by the International Joint Research Project (ASIA-16-011) of the NST (National Research Council E
DOI: 10.1021/acs.jnatprod.7b00882 J. Nat. Prod. XXXX, XXX, XXX−XXX
