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Mar 12, 2015 - The mycelia and culture broth of P. aculeatum SD-321 were exhaustively extracted with MeOH and EtOAc, respectively. The combined extrac...
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Antimicrobial Phenolic Bisabolanes and Related Derivatives from Penicillium aculeatum SD-321, a Deep Sea Sediment-Derived Fungus Xiao-Dong Li,†,‡ Xiao-Ming Li,† Gang-Ming Xu,† Peng Zhang,†,‡ and Bin-Gui Wang*,† †

Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Nanhai Road 7, Qingdao 266071, People’s Republic of China ‡ University of Chinese Academy of Sciences, Yuquan Road 19A, Beijing 100049, People’s Republic of China S Supporting Information *

ABSTRACT: Three new phenolic bisabolane sesquiterpenes, peniciaculins A (1) and B (2) and (7S)-(−)-10-hydroxysydonic acid (3), together with a new nor-bisabolane derivative, 1-hydroxyboivinianin A (4), as well as six known bisabolanes (5−10), were identified from the culture of Penicillium aculeatum SD-321, a fungus isolated from deep-sea sediments. The structures of these compounds were mainly determined by analysis of spectroscopic data, and the absolute configurations of compounds 1−4 were established by comparing their ECD spectra with those of known analogues or by TDDFT-ECD calculations. Compound 1 represents the first example of a bisabolane analogue linked to a diphenyl ether moiety via an ether bond, while compound 2 appears to be the first dimeric bisabolane analogue where the two monomers are coupled to each other via an ester bond. The isolated compounds were evaluated for antimicrobial activity against 10 human and aquatic pathogenic bacteria and three plant-pathogenic fungi.

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the isolation, structure elucidation, and bioactivity evaluation of compounds 1−10.

arine organisms have been recognized as a rich source of structurally unique and biologically potent secondary metabolites. The aromatic bisabolane derivatives are a rarely observed family of sesquiterpenes. Several phenolic bisabolanetype sesquiterpenes have been isolated from marine organisms, such as the gorgonian Pseudopterogorgia rigida,1 the sponges Didiscus flavus2 and Myrmekioderma styx,3 and from marinederived strains of the fungi Verticillium tenerum,4 Aspergillus sp.,5 and Aspergillus sydowii.6 The bisabolane sesquiterpenes have received considerable attention due to their multiple biological activities such as acetylcholinesterase inhibitory activity,7 antioxidant potency,8 cytotoxicity,9 and antibacterial properties.10 In our continuing research for bioactive secondary metabolites from marine-derived fungi,11−15 three new phenolic bisabolane sesquiterpenes, peniciaculins A and B (1 and 2) and (7S)-(−)-10-hydroxysydonic acid (3), as well as a new norbisabolane derivative 1-hydroxy-boivinianin A (4), and six known bisabolane sesquiterpenes (5−10), were isolated and identified from the culture extract of Penicillium aculeatum SD321, a fungus obtained from a deep-sea sediment sample that was collected from the South China Sea. The structures of these compounds were established by extensive analysis of spectroscopic data, and the absolute configurations of compounds 1−4 were determined by comparing their ECD spectra with those of related known analogues or by ECD calculations. The antimicrobial activities against 10 human and aquatic pathogenic bacteria and three plant-pathogenic fungi, as well as the brine shrimp lethality against Artemia salina, were determined for the isolated compounds. This paper describes © XXXX American Chemical Society and American Society of Pharmacognosy

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RESULTS AND DISCUSSION The mycelia and culture broth of P. aculeatum SD-321 were exhaustively extracted with MeOH and EtOAc, respectively. The combined extracts were further purified by column chromatography (CC) on silica gel, Lobar LiChroprep RP-18, and Sephadex LH-20, as well as by semipreparative HPLC, to yield compounds 1−10. Compound 1 was obtained as a white amorphous powder. The molecular formula was determined as C29H36O5 on the basis of HRESIMS data, implying 12 degrees of unsaturation. The 13C NMR along with DEPT spectroscopic data (Table 1) revealed the presence of 29 carbon atoms, which were clarified into 10 nonprotonated carbons, 10 methines (with nine aromatic), four methylenes (with one oxygenated), and five methyls. Detailed analysis of the 1D and 2D NMR spectra displayed signals for two structural moieties, which were identified as a diphenyl ether moiety (I in Figure 1) similar to diorcinol,16 and a bisabolane unit (II in Figure 1) similar to sydonol.17 However, the 13C NMR signal of C-1′ shifted from δC 158.4 in diorcinol (numbered as C-3′)16 to δC 159.9 in 1 (Table 1), and the NMR signals of H-15 (δH 4.46) and C-15 (δC 64.2) in sydonol17 moved to δH 4.90 (H-15) and δC 69.5 (C-15) in the NMR spectra of 1 (Table 1). The above data as well as the observed HMBC correlation from H-15 to C-1′ Received: January 2, 2015

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monomers are linked via an ester bond to be observed in natural products. Compound 3 was isolated as a white amorphous powder. Its molecular formula was determined to be C15H22O5 on the basis of HRESIMS data, indicating five degrees of unsaturation. Its NMR data (Table 2) displayed signals similar to those of sydonic acid (7),19 revealing that 3 also belongs to the family of phenolic bisabolanes. The main difference in 1D NMR data between 3 and 7 is observed for the resonances in the aliphatic chain. The observed signals for H-10 (δH 3.06) and C-10 (δC 74.9) proved the substitution of a hydroxy group at C-10 of 3. In addition, the deshielded resonance of C-9 (δC 28.4) and the shielded resonances of C-12 (δC 17.4) and C-13 (δC 19.0) as well as the observed COSY correlations from H2-9 to H2-8 and H-10 and from H-10 to H-11 (Figure 1) supported this deduction. Further evidence was observed by the key HMBC correlations from H2-8, H3-12, and H3-13 to C-10 (Figure 1). Thus, the planar structure of 3 was determined to be 10hydroxysydonic acid. The absolute configuration of C-7 in compound 3 was also determined as S by comparison of the ECD spectrum (Figure 2) with that of (S)-(+)-sydonol.18 Attempts to determine the absolute configuration of C-10 in 3 by using the modified Mosher’s method failed, probably due to the presence of the carboxylic acid group and several hydroxy groups in 3. The compound was obtained as an amorphous powder and attempts to cultivate single crystals were unsuccessful, precluding the possibility of assigning the absolute configuration at C-10 by X-ray crystallography. Compound 4 has the molecular formula C12H14O3 as determined by HRESIMS data. The NMR data of 4 (Table 2) displayed similar signals to those of boivinianin A, a trisnorbisabolane sesquiterpene isolated from the plant Cipadessa boiviniana collected from the northwest area of Madagascar.20 However, two pairs of symmetric proton signals for the phenyl group of boivinianin A20 were replaced by one singlet (δH 6.69, H-6) and two doublets (δH 7.03 and 6.55, J = 7.8 Hz, H-3 and H-4) in the 1H NMR spectrum of 4 (Table 2). This difference was corroborated by the carbon NMR data. Signals corresponding to symmetric methine carbons of the phenyl group in boivinianin A were absent in the 13C NMR spectrum of 4, whereas one oxygenated aromatic carbon (δC 154.2, C-1) and three methine carbons (δC 124.8/C-3, 119.4/C-4, and 117.3/C-6) were observed. These data suggested the substitution of an OH group at C-1 of the phenyl ring of 4, which was supported by the HMBC correlations from H-3 to C-1 (Figure 1). On the basis of the above discussion, the structure of compound 4 was determined as 1-hydroxyboivinianin A. To establish the absolute configuration of compound 4, the ECD spectrum was computed with the time-dependent density function theory (TDDFT) at the gas-phase B3LYP/631G(d) level,21,22 and the calculated ECD spectra were produced by SpecDis software.23 The results indicated that the computed ECD of 7R isomer of 4 matched well with that of the experimental ECD spectrum (Figure 3), and the absolute configuration was therefore assigned as 7R. In addition to the new phenolic bisabolane-related compounds 1−4, six known bisabolane-type sesquiterpenes (5−10) were also isolated. By detailed spectroscopic analyses, as well as by comparisons with reported data, the structures of compounds 5−10 were identified as expansol D (5),24 (7S,11S)-(+)-12-hydroxysydonic acid (6),25 sydonic acid (7),19 hydroxysydonic acid (8),19 (S)-(+)-11-dehydrosydonic acid (9),26 and 7-deoxy-7,14-didehydrosydonic acid (10).5

indicated the connection of moieties I and II via an ether bond between C-15 and C-1′ (Figure 1) and allowed the determination of the planar structure of 1. The ECD spectrum of compound 1 showed a negative Cotton effect (CE) near 209 nm and two positive CEs around 225 and 282 nm (Figure 2), similar to that of (S)(+)-sydonol,18 which enabled the assignment of the absolute configuration for C-7 of 1 as S. The structure of peniciaculin A (1) is thus determined as shown. Compound 1 is the first example of a bisabolane analogue linked to a diphenyl ether moiety via an ether bond, which has not been described yet in natural products. The molecular formula of compound 2 was determined to be C30H44O6 on the basis of HRESIMS, implying nine degrees of unsaturation. The 13C NMR spectroscopic data (Table 1) revealed the presence of 30 carbon signals, which were clarified by DEPT and HSQC spectra into the categories of nine nonprotonated carbons, eight methines (with six aromatic), seven methylenes (with one oxygenated), and six methyls. Detailed analysis of the spectroscopic data indicated that compound 2 is a dimeric analogue of two bisabolane sesquiterpenes, with the first one related to sydonol,17 the same as moiety II in that of compound 1, while the second one is moiety III (Figure 1), derived from sydonic acid (7).19 HMBC correlations from H-15′ in moiety II to C-15 in moiety III indicated that the two moieties were connected to each other via an ester bond between C-15 and C-15′ (Figure 1). On the basis of the above spectroscopic evidence, the structure of 2 was determined and named peniciaculin B. The absolute configuration of compound 2 was assigned as 7S, 7′S, based on the similar CEs observed in its experimental ECD spectrum to that of (S)-(+)-sydonol (Figure 2).18 Compound 2 appears to be the first dimeric bisabolane derivative, where the two B

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Table 1. NMR Data for Compounds 1 and 2 in DMSO-d6 (1H at 500 MHz, 13C at 125 MHz) 1 position

2

δC, type

1 2 3 4 5 6 7 8

156.2, C 132.4, C 127.0, CH 117.8, CH 136.6, C 116.0, CH 75.6, C 42.5, CH2

9 10 11 12 13 14 15 1′ 2′ 3′ 4′ 5′ 6′ 7′ 8′

21.8, CH2 39.3, CH2 27.7, CH 22.9, CH3 23.0, CH3 29.0, CH3 69.5, CH2 159.9, C 103.1, CH 158.1, C 112.0, CH 140.6, C 110.1, CH 21.6, CH3 157.8, C

9′ 10′ 11′ 12′ 13′ 14′ 15′

103.6, CH 159.4, C 112.0, CH 140.4, C 111.0, CH 21.6, CH3

δH (J in Hz)

δC, type

7.16, d (8.0) 6.73, d (8.0) 6.73, br s 1.62, 1.85, 1.22, 1.04, 1.42, 0.75, 0.77, 1.45, 4.90,

ddd (12.4, 12.0, 3.7), ddd (12.4, 12.0, 3.7) m m m d (6.5) d (6.5) s s

6.40, s 6.34, br s 6.20, s 2.21, s

6.16, s

155.3, C 138.8, C 127.0, CH 116.5, CH 128.7, C 117.6, CH 74.4, C 41.1, CH2 21.3, CH2 38.8, CH2 27.2, CH 22.3, CH3 22.3, CH3 28.1, CH3 165.5, C 155.3, C 132.2, C 126.6, CH 119.0, CH 135.5, C 115.2, CH 75.0, C 41.8, CH2 21.3, 38.8, 27.2, 22.5, 22.5, 28.5, 65.4,

6.34, br s 6.55, s 2.16, s

CH2 CH2 CH CH3 CH3 CH3 CH2

δH (J in Hz)

7.44, d (8.1) 7.35, d (8.1) 7.40, s 1.65, 1.97, 1.25, 1.05, 1.42, 0.76, 0.78, 1.49,

ddd (12.8, 12.7, 4.1), ddd (12.8, 12.7, 4.1) m m m d (6.5) d (6.5) s

7.22, d (7.9) 6.78, d (7.9) 6.83, s 1.65, 1.89, 1.26, 1.05, 1.42, 0.77, 0.77, 1.48, 5.17,

ddd (12.6, 11.4, 3.1), ddd (12.6, 11.4, 3.1) m m m d (6.5) d (6.5) s s

Figure 2. CD spectra of compounds 1−3.

hydrophilia, Edwardsiella tarda, Micrococcus luteus, Pseudomonas aeruginosa, Vibrio alginolyticus, Vibrio anguillarum, Vibrio harveyi, and Vibrio parahemolyticus) as well as three plantpathogenic fungi (Alternaria brassicae, Colletotrichum gloeosprioides, and Gaeumannomyces graminis). Compound 1 showed inhibitory activity against M. luteus and V. alginolyticus with MIC values of 1.0 and 2.0 μg/mL, while compounds 2 and 4 exhibited selective antibacterial activity against E. tarda and V. harveyi, with MIC values of 8.0 and 4.0 μg/mL (Table 3), respectively. Compound 6 showed significant inhibitory activity

Figure 1. COSY (bold lines) and key HMBC (arrows) correlations of compounds 1−4.

Compounds 1−10 were evaluated for antimicrobial activity against two pathogenic bacteria (Escherichia coli and Staphyloccocus aureus) and eight aquatic pathogens (Aeromonas C

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Table 2. NMR Data for Compounds 3 and 4 in DMSO-d6 (1H at 500 MHz, 13C at 125 MHz) 3 position

δC, type

1 2 3 4 5 6 7 8

154.6, C 139.0, C 125.2, CH 119.4, CH 132.9, C 117.3, CH 75.3, C 38.4, CH2

9

28.4, CH2

10 11 12 13 14 15

74.9, CH 32.8, CH 17.4, CH3 19.0, CH3 28.7, CH3 170.5, C

4 δH (J in Hz)

δC, type 154.2, C 127.9, C 124.8, CH 119.4, CH 138.3, C 117.3, CH 86.6, C 34.1, CH2

7.09, d (7.4) 7.25, d (7.4) 7.33, s 1.65, 2.06, 1.13, 1.36, 3.06, 1.45, 0.75, 0.76, 1.49,

δH (J in Hz)

ddd (13.2, 13.1, 4.0), dt (13.1, 4.1) m, m m m d (6.7) d (6.7) s

7.03, d (7.8) 6.55, d (7.8) 6.69, s 2.33, 2.47, 2.33, 2.60,

28.9, CH2 177.0, C 26.8, CH3 21.1, CH3

m, m m, m

1.64, s 2.17, s

mL, while compounds 7 and 10 exhibited significant inhibitory activity on G. graminis with an MIC value of 0.5 μg/mL, which is more potent than that of the positive control amphotericin B (MIC 64 μg/mL). Compounds 1−10 were also evaluated for lethal activity against brine shrimp (Artemia salina), but none of them displayed significant activity (LD50 > 10 μg/mL).

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EXPERIMENTAL SECTION

General Experimental Procedures. Melting points were determined with an SGW X-4 micromelting-point apparatus. Optical rotations were measured on an Optical Activity AA-55 polarimeter. UV spectra were measured on a PuXi TU-1810 UV−visible spectrophotometer. ECD spectra were acquired on a Chirascan spectropolarimeter. IR spectra were obtained on a Thermo Scientific Nicolet iN10 spectrophotometer. 1D and 2D NMR spectra were recorded at 500 and 125 MHz for 1H and 13C, respectively, on a Bruker Avance 500 MHz spectrometer with TMS as internal standard. Mass spectra were obtained on a VG Autospec 3000 or an API QSTAR Pulsar 1 mass spectrometer. Analytical and semipreparative HPLC were performed using a Dionex HPLC system equipped with a P680 pump, an ASI-100 automated sample injector, and a UVD340U multiple wavelength detector controlled by Chromeleon software

Figure 3. Experimental and calculated ECD spectra of 4.

against S. aureus and V. parahemolyticus with MIC values of 0.5 μg/mL. Regarding the antifungal activity, compound 1 showed inhibitory activity against A. brassicae with an MIC of 0.5 μg/

Table 3. Antimicrobial Activities of Compounds 1−10 (MIC, μg/mL)a compounds strains b

E. coli S. aureusb A. hydrophiliab E. tardab M. luteusb P. aeruginosab V. alginolyticusb V. anguillarumb V. harveyib V. parahemolyticusb A. brassicaec C. gloeosprioidesc G. graminisc a

1

2

3

4

5

6

7

8

9

10

positive

− − − − 1.0 32 2.0 − − − 0.5 − 32

− − − 8 − − − − − 32 32 − −

− 32 32 − − − − − 8.0 32 − − −

32 32 − − − − − − 4.0 − − 32 32

32 − − − 8 4 8 32 − 32 32 32 32

− 0.5 − − − − − − − 0.5 − − 32

− 32 − 32 − − − 32 4.0 4.0 − 32 0.5

32 − 32 − − − − 32 − 32 − − −

− 32 − − 32 − − − 4.0 32 − 32 −

− 32 − − − − − − 4.0 32 − − 0.5

4.0 0.5 4.0 8.0 8.0 8.0 0.5 0.5 4.0 0.5 32 32 64

a

(−) = MIC > 32 μg/mL. bChloramphenicol as positive control. cAmphotericin B as positive control. D

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(7S)-(−)-10-Hydroxysydonic Acid (3). White amorphous powder; [α]20 D −2.6 (c 0.38, MeOH); UV (MeOH) λmax (log ε) 205 (4.40), 236 (1.31), 290 (0.53) nm; CD (0.99 mM, MeOH) λmax (Δε) 208 (−1.32), 225 (+1.01), 289 (+2.82) nm; IR (KBr) νmax 3272, 2966, 1558, 1433, 1240, 1107, 1027, 956, 803, 786 cm−1; 1H and 13C NMR data, Table 2; ESIMS m/z 305 [M + Na]+; HRESIMS m/z 305.1364 [M + Na]+ (calcd for C15H22O5Na, 305.1359). 1-Hydroxyboivinianin A (4). Colorless oil; [α]20 D +25.8 (c 0.49, CHCl3); UV (MeOH) λmax (log ε) 210 (2.76), 280 (0.40) nm; CD (1.36 mM, MeOH) λmax (Δε) 204 (+13.48), 210 (−1.33), 212 (+4.00), 220 (−1.58), 238 (+0.29) nm; IR (KBr) νmax 3252, 2928, 1583, 1506, 1417, 1292, 1130, 949, 865, 808 cm−1; 1H and 13C NMR data, Table 2; ESIMS m/z 229 [M + Na]+; HRESIMS m/z 205.0891 [M − H]− (calcd for C12H13O3, 205.0865). (7S,11S)-(+)-12-Hydroxysydonic Acid (6). Colorless oil; [α]20 D +4.2 25 (c 0.40, MeOH); Lit. [α]25 D +3.9 (c 0.39, MeOH). Sydonic Acid (7). Colorless oil; [α]20 D +3.1 (c 1.09, MeOH); Lit. 18 [α]20 D +2.73 (c 2.30, MeOH). Hydroxysydonic Acid (8). White amorphous powder; [α]20 D +2.2 (c 19 A similar compound, 0.49, MeOH); Lit. [α]24 D 0 (c 1.0, MeOH). 18 curculetraol, was reported to have [α]20 D +5.24 (c 0.74, MeOH). (S)-(+)-11-Dehydrosydonic Acid (9). Colorless oil; [α]20 +13.1 (c D 26 0.38, MeOH); Lit. [α]23 D +10.8 (c 0.11, MeOH). Antimicrobial Assays. Antimicrobial evaluation against two pathogenic bacteria (E. coli EMBLC-1 and S. aureus EMBLC-2, provided by a research group in the Key Laboratory of the Experimental Marine Biology at the authors’ institute) and eight aquatic pathogens (A. hydrophilia QDIO-1, E. tarda QDIO-2, M. luteus QDIO-3, P. aeruginosa QDIO-4, V. alginolyticus QDIO-5, V. anguillarum QDIO-6, V. harveyi QDIO-7, and V. parahemolyticus QDIO-8, provided by a research group in the Key Laboratory of the Experimental Marine Biology at the authors’ institute) as well as three plant-pathogenic fungi (A. brassicae QDAU-1, C. gloeosprioides QDAU2, and G. graminis QDAU-3, provided by a research group in the Qingdao Agricultural University) were carried out by the microplate assay.28 Chloramphenicol and amphotericin B were used as positive controls against bacteria and fungi, respectively. All of the microbial strains used in the bioassays are preserved at the Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences. Brine Shrimp Toxicity Assay. Evaluation of brine shrimp (Artemia salina) toxicity was performed as previously reported.15

(version 6.80). Commercially available Si gel (200−300 mesh, Qingdao Haiyang Chemical Co.), Lobar LiChroprep RP-18 (40−63 μm, Merck), and Sephadex LH-20 (Pharmacia) were used for open column chromatography. All solvents were distilled prior to use. Fungal Material. The fungus Penicillium aculeatum SD-321 was isolated from a marine sediment sample collected in May, 2012, from the South China Sea at a depth of 2038 m. The fungus was identified using a molecular biological protocol by DNA amplification and sequencing of the ITS region, as described in our previous report.27 The sequenced data derived from the fungal strain have been deposited in GenBank (accession no. KM396277). A BLAST search result showed that the sequence was most similar (98%) to the sequence of Penicillium aculeatum (compared to accession no. EU781668.1). The strain is preserved at the Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences. Fermentation, Extraction, and Isolation. For chemical investigations, the fungal strain was statically fermented for 30 days at room temperature in liquid medium containing 20% potato juice, 2% glucose, 0.5% peptone, and 0.3% yeast extract (pH 6.0−6.5). The whole fermented cultures (25 L) were filtered to separate the broth from the mycelia. The former was extracted three times with EtOAc, while the latter was extracted three times with the mixture of acetone and H2O (4:1). The acetone solution was evaporated under reduced pressure to afford an aqueous solution, which was then extracted with EtOAc three times. Because the TLC and HPLC profiles of the two EtOAc solutions were almost identical, they were combined and concentrated under reduced pressure to give an organic extract (28.0 g) for further purification. The organic extract was fractionated by vacuum liquid chromatography (VLC) on silica gel eluting with different solvents of increasing polarity from petroleum ether (PE) to MeOH to yield 10 fractions (Frs. 1−10) based on TLC analysis. Fr. 5 (3.1 g), eluted with PE− EtOAc (1:1), was further purified by Sephadex LH-20 (MeOH) to afford two subfractions (Fr. 5-1 and Fr. 5-2). Fr. 5-1 was further purified by CC over RP-18 eluting with a MeOH−H2O gradient (from 1:9 to 1:0) and by semipreparative HPLC (Elite ODS-BP column, 10 μm; 10.0 mm × 300 mm; MeOH/H2O, from 85% to 90%, flow rate 3 mL/min) to afford compounds 7 (18.3 mg, tR 18.8 min) and 9 (16.7 mg, tR 17.5 min). Fr. 5-2 was further purified by Sephadex LH-20 (MeOH) and by semipreparative HPLC (90% MeOH/H2O, 3 mL/ min) to afford 3 (6.3 mg, tR 20.1 min) and 10 (16.6 mg, tR 19.3 min). Fr. 6 (2.7 g), eluted with CHCl3−MeOH (20:1), was further purified by CC on silica gel, eluting with a PE−acetone gradient (from 10:1 to 1:1), and by semipreparative HPLC (85% MeOH/H2O, 3 mL/min) to afford 1 (5.4 mg, tR 17.5 min) and 5 (7.0 mg, tR 16.1 min). Fr. 7 (1.2 g), eluted with CHCl3−MeOH (10:1), was purified by CC on silica gel eluting with a CHCl3−MeOH gradient (30:1 to 10:1) to afford two subfrations (Fr. 7-1 and Fr. 7-2). Fr. 7-1 was further purified by CC over RP-18 eluting with a MeOH−H2O gradient (1:9 to 1:0) and by semipreparative HPLC (MeOH/H2O, 80−85%, 3 mL/min) to obtain 2 (25.3 mg, tR 18.8 min). Fr. 7-2 was further purified by Sephadex LH-20 (MeOH) and by semipreparative HPLC (80% MeOH/H2O, 3 mL/min) to yield 4 (1.9 mg, tR 14.1 min), 6 (34.9 mg, tR 15.3 min), and 8 (25.0 mg, tR 16.8 min). Peniciaculin A (1). White amorphous powder; [α]20 D +4.1 (c 0.49, MeOH); UV (MeOH) λmax (log ε) 212 (5.21), 280 (2.08) nm; CD (0.60 mM, MeOH) λmax (Δε) 209 (−0.81), 225 (+1.98), 282 (+2.80) nm; IR (KBr) νmax 3270, 2928, 2867, 1584, 1458, 1325, 1154, 1122, 1052, 834 cm−1; 1H and 13C NMR data, Table 1; ESIMS m/z 487 [M + Na]+; HRESIMS m/z 463.2488 [M − H]− (calcd for C29H35O5, 463.2479). Peniciaculin B (2). White amorphous powder; [α]20 D +5.6 (c 0.34, MeOH); UV (MeOH) λmax (log ε) 205 (4.20), 215 (3.69), 247 (1.28), 285 (0.49) nm; CD (0.78 mM, MeOH) λmax (Δε) 208 (−1.32), 224 (+2.01), 282 (+3.31) nm; IR (KBr) νmax 3240, 2953, 2869, 1699, 1577, 1420, 1383, 1297, 1215, 1169, 1097, 1026, 768 cm−1; 1H and 13C NMR data, Table 1; ESIMS m/z 523 [M + Na]+; HRESIMS m/z 523.3035 [M + Na]+ (calcd for C30H44O6Na, 523.3030).

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ASSOCIATED CONTENT

S Supporting Information *

Selected 1D and 2D NMR spectra of compounds 1−4 and ECD spectra of compounds 1−3. This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*Phone/Fax: +86-532-82898553. E-mail: [email protected]. cn. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was financial supported by the Ministry of Science a n d T e c h n o l o g y o f Ch i n a ( 20 1 2A A0 92 1 04 a n d 2013AA092901) and by the NSFC-Shandong Joint Fund for Marine Science Research Centers (U1406402).

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REFERENCES

(1) D’Armas, H. T.; Mootoo, B. S.; Reynolds, W. F. J. Nat. Prod. 2000, 63, 1593−1595. (2) Sugahara, T.; Ogasawara, K. Tetrahedron: Asymmetry 1998, 9, 2215−2217. E

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DOI: 10.1021/acs.jnatprod.5b00004 J. Nat. Prod. XXXX, XXX, XXX−XXX