Skip to main content
NCBI home page
3 Biotech logoLink to 3 Biotech
. 2021 Jul 30;11(8):391. doi: 10.1007/s13205-021-02877-7

NF-κB inhibitory, antimicrobial and antiproliferative potentials of compounds from Hawaiian fungus Aspergillus polyporicola FS910

Cong Wang 1,2, K H Ahammad uz Zaman 1, Ariel M Sarotti 3, Xiaohua Wu 1, Shao-Liang Zheng 4, Shugeng Cao 1,✉
PMCID: PMC8324597  PMID: 34458061

Abstract

Bioassay-guided experimental design and chromatographic analysis led to the isolation and identification of ten compounds (1–10) including two unusual sulfur-containing curvularin macrolides (1 and 2) from a Hawaiian fungal strain Aspergillus polyporicola FS910. Compounds 1 and 2 are rare curvularin macrolides each with a five-membered cyclic sulfur-containing moiety. The structures of the compounds were identified by HRESIMS, NMR spectroscopy, X-ray crystallography, ECD and DFT energy calculation, as well as comparing with previous literatures. Compounds 4, 6 and 8 were active against TNF-α-induced NF-κB inhibitory activity with IC50 values of 26.45, 5.41 and 15.8 µM, respectively. Compounds 3 and 5–8 exhibited anti-proliferative activity against HT1080, T46D, and A2780S cell lines, with IC50 values ranging from 2.48 to 29.17 μM. Additionally, Compound 3 showed promising antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA), Bacillus subtilis, Escherichia coli and Candida albicans. Moreover, when tested in combination with antibiotic adjuvant disulfiram [4 µg/mL], compounds 4, 5 and 10 also displayed significant antibacterial activity against S. aureus.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-021-02877-7.

Keywords: Aspergillus polyporicola, Curvularin macrolides, ECD, Anti-bacterial activity, NF-κB inhibitory activity

Introduction

Due to low costs and potent bioactivities, as well as more opportunity of getting unique structures, natural product drug discovery has reclaimed the interest of chemists, biologists, and pharmacologists among the three pathways for discovering new drug molecules: rational drug design, chemical synthesis and natural product discovery (Newman and Cragg 2020). Although natural products from plants have been considered to be one of the most promising, the quantity and variety of bioactive compounds from plant tissues are not satisfactory anymore. Recently, endophytes from both plants and animals have become a hot spot and been recognized to be underexplored resources for the discovery of new biologically active natural products (Martinez-Klimova et al. 2017; Alvin et al. 2014).

Although some of the Aspergillus species are medically relevant pathogens, most of them (around 80%) are harmless and have been proven to be a source of structurally diverse and biologically active secondary metabolites (Thom and Church 1926). The Aspergillus Secondary Metabolites Database (A2MDB) records 807 unique natural products derived from 675 Aspergillus species; A2MDB also documents a total of 44 secondary metabolic pathways (Vadlapudi et al. 2017).

In our search for new biologically active compounds from Hawaiian fungi (Li et al. 2015a, b, 2016a, b, 2017, 2018a, b, 2019; Fei-Zhang et al. 2016; Huang et al. 2017; Wang et al. 2019, 2020a, b; Zaman et al. 2020a, b), we studied Aspergillus polyporicola FS910 which was isolated from a soil sample collected at Haleakala Highway, Maui, Hawaii in May 2015. An extract of FS910 (20 μg/mL), inactive when tested alone, showed inhibitory activity against S. aureus in the presence of disulfiram (20 μM). Disulfiram is an aldehyde dehydrogenase (ALDH) inhibitor and an FDA-approved drug used to support the treatment of chronic alcoholism (up to 500 mg daily); however, it can enhance the antimicrobial efficacy of FDA-approved antibiotics as well as some inactive natural products (Wang et al. 2020b). Through assay-guided separation using disulfiram (4 µg/mL) in antibacterial assay, we isolated ten secondary metabolites from A. polyporicola FS910. Herein, we present the isolation, structural determination, plausible biosynthesis, biological evaluation of these metabolites.

Methods and materials

General experimental procedures

Melting points were determined with a B-540 micromelting-point apparatus. Optical rotations, ECD and FT-IR spectra were measured with a Rudolph research analytical autoPol automatic polarimeter, JASCO J-815 ECD and Thermo scientific nicolet iS10 IR spectrometer, respectively. 1D and 2D NMR spectra were recorded on a Bruker AM-400 spectrometer. The 3.35 ppm and 49.3 ppm resonances of CD3OD, and the 2.50 ppm and 39.5 ppm resonances of DMSO-d6, were used as internal references for 1H and 13C NMR spectra, respectively. An Agilent 6530 accurate-Mass Q-TOF LC–MS spectrometer was used to record high-resolution mass spectra. Preparative HPLC was carried out on an Ultimate 3000 chromatographic system with a Phenomenex preparative column (Phenyl-Hexyl, 5 µm, 100 × 21.2 mm) and semi-preparative HPLC on an Ultimate 3000 chromatographic system with a Phenomenex semi-preparative column (C18, 5 µm, 250 × 10 mm), a Dionex Ultimate 3000 DAD detector and a Dionex Ultimate 3000 automated fraction collector; and all solvents were HPLC grade. Diaion HP-20 was used to run open-column chromatography.

Strain isolation and fermentation

The strain FS910 was isolated from a soil sample collected at Haleakala Hwy (latitude: 20.755313 °N; Longitude: −156.275555 °W), Maui, Hawaii, in May 2015. The rDNA ITS1-4 region sequence of fungus has been submitted to GenBank (Accession number MT239490). The strain was deposited in −80 °C freezer at Daniel K. Inouye College of Pharmacy, University of Hawaii at Hilo, HI, USA. The strain was grown on PDA plates at 28 °C for 3 days, and then it was cut into small pieces and inoculated into 20 L autoclaved sterilized liquid PDB medium for fermentation at 24 °C for 30 days.

Extraction and isolation

After filtering of the fermentation broth of FS910 (20 L), the mycelia were extracted three times by acetone. Acetone was removed by evaporation in vacuum. After combining supernatant solution and the aqueous mycelia extraction, the combined extract (6.83 g) was subjected to HP-20 column eluted with MeOH-H2O into four fractions (30%, 50%, 90% and 100%). Fraction 3 (3.79 g) was separated by prep-HPLC (Phenyl-Hexyl, 100 × 21.20 mm, 5 µm; 8 mL/min) eluted with 40–100% MeOH-H2O in 20 min to yield 26 sub-fractions (SFr 3–1 ~ 26). SFr 3–9 (910 mg) was purified by semi-preparative HPLC (35% MeCN/H2O, v/v, 3.0 mL/min) over a C18 column to afford sub-SFr 3–9–5, compounds 3 (11.2 mg, tR 8.2 min), 4 (1.2 mg, tR 10.2 min), and 5 (1.6 mg, tR 25.9 min). SFr 3–9–5 (280 mg) was purified by semi-preparative HPLC (53% MeOH/H2O, v/v, 1.0‰ formic acid, 3.0 mL/min) over a C18 column to afford compounds 1 (11.0 mg, tR 20.6 min) and 2 (16.7 mg, tR 28.2 min) (Fig. 1). SFr 3–10 (126.8 mg) was purified by semi-preparative HPLC (55% MeOH/H2O, v/v, 1.0‰ formic acid, 3.0 mL/min) over a C18 column to afford compounds 6 (3.8 mg, tR 8.2 min) and 7 (1.5 mg, tR 15.2 min). SFr 3–14 (202.2 mg) was purified by semi-preparative HPLC (40% MeCN/H2O, v/v, 1.0‰ formic acid, 3.0 mL/min) over a C18 column to afford compound 8 (7.1 mg, tR 17.7 min). SFr 3–12 (162.9 mg) was purified by semi-preparative HPLC (40% MeCN/H2O, v/v, 1.0‰ formic acid, 3.0 mL/min) over a C18 column to afford compound 9 (2.5 mg, tR 29.3 min). SFr 3–11 (83.3 mg) was purified by semi-preparative HPLC (35% MeCN/H2O, v/v, 1.0‰ formic acid, 3.0 mL/min) over a C18 column to afford compound 10 (1.1 mg, tR 22.7 min) (Fig. 1).

Fig. 1.

Fig. 1

Open in a new tab

Structures of compounds 1–10

X-ray crystallographic analysis of compounds 1 and 2

Crystals mounted on a diffractometer were collected data at 100 K. The intensities of the reflections were collected by means of a Bruker APEX II CCD diffractometer (MoKα radiation, λ = 0.71073 Å), and equipped with an Oxford Cryosystems nitrogen flow apparatus. The collection method involved 0.5 ° scans in ω at 28° in 2θ. Data integration down to 0.78 Å resolutions was carried out using SAINT V8.37A (Bruker diffractometer, 2016) with reflection spot size optimization. Absorption corrections were made with the program SADABS (Bruker 2016). The structure was solved by the Intrinsic Phasing methods and refined by least-squares methods again F2 using SHELXT-2014 (Bruker 2016) and SHELXL-2014 (Sheldrick 2015) with OLEX 2 interface (Dolomanov et. al. 2009). Non-hydrogen atom was refined anisotropically, and hydrogen atoms were allowed to ride on the respective atoms.

Antibacterial assay

Antibacterial assay was conducted by the previously described method (Zaman et al. 2020a, b). Additionally, samples were applied along with the antibiotic adjuvant [disulfiram for S. aureus] with their final concentration at 4 µg/mL. DMSO [5%] as well as antibiotic adjuvents [4 µg/mL] was used as negative controls whereas chloramphenicol was used as a positive control, which was active against S. aureus, methicillin-resistant S. aureus, B. subtilis and E. coli with MIC values ranging from 2.5 µg/ml to 12.5 µg/ml. The maximum concentration of the used compounds was 80 µg/ml. All experiments were repeatedly performed in triplicate.

Antifungal assay

Fungus was grown on Muller Hinton agar plates for 1 day at 37 °C and then added to the sterile distilled water to make a 1 × 105 CFU/mL fungal inoculum. Compounds and positive control (5 μL) and 195 μL of Muller Hinton broth media were introduced into the first wells of a microtiter plate in columns 1–10 (in row A). Rows B–H in columns 1–10 were filled with 100 μL of broth alone. 100 μL was removed from the starting concentrations (columns 1–10 in row A) and transferred to the next row with the 100 μL broth, properly mixed, and the procedure was repeated up to the last row (H) where the last 100 μL was discarded. An equal volume (100 μL) of the 1 × 105 CFU/mL fungal inoculum was transferred into all the wells except the 12th column: sterility control, contained only 200 μL of broth. Column 11 served as growth control (drug-free)-containing media and the inoculum. The sample concentrations ranged from 80 to 0.625 μg/mL. Microtiter plates were incubated at 37 °C for 48 h. After incubation, 20 μL of resazurin dye (0.015% w/v) was added to all the wells and incubated for 4 h to observe any color changes. DMSO [5%] was used as a negative control whereas amphotericin B was used as a positive control, with MIC value of 0.625 μg/mL. All experiments were repeatedly performed in triplicate.

Anti-proliferative assays

Viability of fibrosarcoma HT1080 cell line, T46D breast cancer cell line and human ovarian cancer cell line A2780S were determined using the CyQuant assay according to the manufacturer's instructions (Life Technologies, CA, USA). Briefly, cells were cultured in 96-well plates at 1,000 cells per well for 24 h and subsequently treated with compounds (20 μg/mL) for 72 h and analyzed. Relative viability of the treated cells was normalized to the DMSO-treated control cells (Lin et al. 2009; Chen et al. 2015). Cisplatin was used as a positive control, which had IC50 values of 0.075, 0.0045, and 0.0081 µM against HT1080, T46D and A2780S, respectively. All experiments were performed in triplicate.

NF-κB assay

We employed HEK 293 from Panomics for monitoring changes occurring along the NF-κB pathway (Kondratyuk et al. 2012). Stable constructed cells were seeded into 96-well plates at 20 × 103 cells per well. Cells were maintained in Dulbecco’s modified Eagle’s medium (DMEM) (Invitrogen Co.), supplemented with 10% FBS, 100 units/mL penicillin, 100 μg/mL streptomycin, and 2 mM L-glutamine. After 48 h incubation, the medium was replaced and the cells were treated with various concentrations of test substances. TNF-α (human, recombinant, E. coli, Calbiochem) was used as an activator at a concentration of 2 ng/mL (0.14 nM). The plate was incubated for 6 h. Spent medium was discarded, and the cells were washed once with PBS. Cells were lysed using 50 µL (for 96-well plate) of reporter lysis buffer from Promega, by incubating for 5 min on a shaker, and stored at − 80 °C. The luciferase assay was performed using the Luc assay system from Promega. The gene product, luciferase enzyme, reacts with luciferase substrate, emitting light, which was detected using a luminometer (LUMIstar Galaxy BMG). Data for NF-κB inhibition are expressed as IC50 values (i.e., concentration required to inhibit TNF-α-induced NF-κB activity by 50%). As positive controls, two known NF-κB inhibitors were used, TPCK (Nα-tosyl-l-phenylalanine chloromethyl ketone) and BAY-11–7082 (which selectively and irreversibly inhibits NF-κB activation by blocking TNF-α-induced phosphorylation of IκB-α without affecting constitutive IκB-α phosphorylation), yielding IC50 values of 5.3 ± 0.9 and 11 ± 1.8 μM, respectively. All experiments were performed in triplicate.

SRB assay

To assess the potential of mediating a cytotoxic response, the cells were treated under the same experimental conditions with each test compound at a concentration of 50 μM, and cell survival was determined by the sulforhodamine B (SRB) assays. After incubation of HEK 293 cells with test compounds, cells were fixed with 10% trichloroacetic acid solution for 30 min and stained with 0.4% SRB in 1% acetic acid solution for 30 min. Protein-bound SRB was dissolved in 10 mM Tris buffer (pH 10.0) and the absorbance was measured at 515 nm. The effect of compounds on cell survival was demonstrated as percentage survival in comparison with vehicle (DMSO)-treated control cells.

Computational details

All the DFT calculations were performed with Gaussian 09 (Frisch et al. 2009). For each compound, a stochastic conformational sampling (100.000 steps) was carried out at the MMFF level in Macromodel using the Mixed torsional/Low-mode with an extended torsion sampling options (Macromodel 2018). All conformers found within a 10 kcal/mol cutoff window (the total number of unique conformations found was 178 for the eight compounds under study) were re-optimized at the SMD/B3LYP/6-31G* level using methanol as solvent. Frequency calculations were done for all optimized geometries at the same level to determine the nature of the stationary point found, and to compute the thermochemical properties (at 1 atm and 298.15 K). The global minima structures found for each compound were fully re-optimized at the SMD/ωB97X-D/6–311+ G** level with methanol as solvent. The ECD calculations were carried out using the SMD/B3LYP/6-31G* optimized geometries of 1 and 2. The excitation energies (nm) and rotatory strengths (R) in dipole velocity (Rvel) of the first forty singlet excitations were calculated using TDDFT implemented in Gaussian 09 at the B3LYP/TZVP level of theory from all significantly populated conformers, which were averaged using Boltzmann weighting. The calculated rotatory strengths were simulated into the ECD curve as the sum of Gaussians with 0.5 eV width at half-heights (σ).

Results and discussion

Structural characterization of isolated compounds

Compound 1 was obtained as colorless crystals and its molecular formula was determined as C19H22O8S by HRESIMS. The 13C NMR and 1H NMR data of 1 were the same as those of cyclothiocurvularin A (de Castro et al. 2016). The absolute configuration of compound 1 was unambiguously determined by single-crystal X-ray diffraction as 10R, 11R, 15S, and 18S (Fig. 2a, CCDC 2026987) with Flack(x) = −0.022(11), Hooft(y) = 0.021(10) (Spek 2009).

Fig. 2.

Fig. 2

Open in a new tab

X-ray crystallographic structures of compound 1 (a) and compound 2 (b)

Compound 2 was also obtained as colorless crystals and has the same molecular formula C19H22O8S derived from the HRESIMS peak at m/z 411.1113 [M + H]+ as 1. The NMR data of compound 2 were very similar to those of compound 1. Interestingly compounds 2 and 1 had nearly opposite ECD signals (Fig. 3) as if they were enantiomers, which was excluded because they could be separated using non-chiral HPLC column. We proposed that both compounds 1 and 2 should have the same configuration at 15-position, but the two tetrahydrothiophene moieties in 1 and 2 should be “mirror images”. To validate this proposal, we undertook TDDFT-ECD calculations at the B3LYP/TZVP//SMD/B3LYP/6-31G* level of theory. The initial MMFF conformational search furnished 15 and 16 conformations of 1 and 2, respectively, using a 10 kcal/mol cutoff window. After reoptimization at the SMD/B3LYP/6-31G* level using methanol as solvent we selected the low-energy conformers with conformational amplitudes above 5% (two in each case) for further ECD computations at the B3LYP/TZVP level. All stable conformations were characterized by an intramolecular H-bonding between the OH group at C-18 and the ketone group at C-9. The Boltzmann-averaged computed ECD spectra of 1 and 2 showed similar signal patterns as the experimentally recorded CD of 1 and 2, respectively, with both calculated spectra showing a pseudo-mirror image relationship in the 250–400 nm region (Fig. 4). In agreement with our hypothesis, the results indicate that the ECD spectrum is governed mainly by the handedness of the tetrahydrothiophene fragment. Fortunately, suitable crystals (0.10 × 0.12 × 0.14 mm) were obtained for an X-ray crystallographic study by dissolving the compound 2 in MeOH-H2O (30:1, v/v) and keeping in room temperature for three weeks. The absolute configuration of compound 2 was also unambiguously determined by single-crystal X-ray diffraction as 10S, 11S, 15S, and 18R (Fig. 2b, CCDC 2026988) with Flack(x) = 0.01(3), Hooft(y) = 0.01(2). Moreover, the NMR data of compound 2 were the same as those of cyclothiocurvularin B (de Castro et al. 2016).

Fig. 3.

Fig. 3

Open in a new tab

Experimental ECD spectra of 1 and 2

Fig. 4.

Fig. 4

Open in a new tab

ECD spectra computed for 1 and 2 at the B3LYP/TZVP//SMD/B3LYP/6-31G* level of theory

Eight other compounds 11-α-hydroxycurvularin (3) (Lai et al. 1989), curvulone A (4) (Dai et al. 2010), dehydrocurvularin (5) (Arai et al. 1989), 11-β-gydroxycurvularin (6) (Lai et al. 1989), 11-β-methoxycurvularin (7) (Liang et al. 2007), citreofuran (8) (Lai et al. 1989), cyclic 9-Deoxy-seco-PF1233 B carboxylic acid (9) (Aparicio-Cuevas et al. 2017), and seco-PF1233 B carboxylic acid (10) (Aparicio-Cuevas et al. 2017) were obtained. The structures of these known compounds were determined on the basis of comparisons of NMR and ESIMS data with previously reported data.

Plausible biosynthetic pathways of compounds 1 and 2

Biogenetically, compounds 1 and 2 might be derived from compound 5 and 3-mercaptopyruvic acid through a Michael addition, followed by a cyclization from C-10 of 5 to C-2' of 3-mercaptopyruvic acid, which could be an oxidized product of 3-mercaptolactic acid or a transaminated product of cysteine. The Michael additions from the top and bottom could yield two diastereoisomeric intermediates, pro-1 and pro-2, respectively, each of which could yield up to four diastereoisomers after the intramolecular aldol-like cyclization. However, only the corresponding compounds showing a C-11/C-10/C-18 anti/syn stereotriad were isolated (compounds 1 and 2). To reinforce our proposed biosynthesis, we undertook DFT energy calculations of all the possible isomers of 1 and 2 (Figures S3 and S4). Following a similar procedure discussed during the ECD calculations, the structures of all MMFF conformations found within a cutoff window of 10 kcal/mol were fully optimized at the SMD/B3LYP/6-31G* using methanol as solvent. Our calculations clearly showed that 1 and 2 are considerably more stable than their corresponding isomers (1'/1"/1"' and 2'/2"/2'", respectively), with Gibbs free energy differences in range 1.9–4.9 kcal/mol (Tables S4, S5, S6 and S7). The C-10/C-18 syn isomers allowed the formation of an intramolecular hydrogen bonding between the 18-OH and the 10-C = O groups, more stabilizing than the interaction between 18-OH and 7-OH taking place in the trans counterparts. Similar results were obtained at the SMD/ωB97X-D/6–311 + G** level (Tables S8, S9, and S10), which validated the proposed biosynthetic pathway (Fig. 5).

Fig. 5.

Fig. 5

Open in a new tab

Plausible biosynthetic pathways of compounds 1 and 2

MIC of the bioactive compounds

Compounds 1–10 were assayed for their antibacterial activity against S. aureus, MRSA, B. subtilis, and E. coli (Table 1). Only compound 5 was marginally active against S. aureus with an MIC value of 40 µg/mL, while compounds 3–5 and 10 inhibited S. aureus at 5 µg/mL in the presence of disulfiram (4 µg/mL). Compound 3 also exhibited inhibition against MRSA, B. subtilis, and E. coli with MIC values of 20, 20, and 40 µg/mL, respectively, and its activity was not enhanced by the addition of antibiotic adjuvants. Compounds 1–10 were also assayed for their antifungal activity against C. albicans (Table 1). Compounds 3 and 5–7 were active against C. albicans with MIC values of 10, 40, 40, and 40 µg/mL, respectively. Compound 3 inhibited all the bacterial and fungal strains, and its activity might be due to its toxicity. It was very interesting that compounds 3, 4 and 10, which were inactive against S. aureus when tested alone at 80 µg/mL, inhibited S. aureus with an equal MIC value of 5 µg/mL when tested together with 4 µg/mL of disulfiram. The anti-S. aureus activity of the weakly active compound 5 was also enhanced dramatically in the presence of disulfiram (4 µg/mL).

Table 1.

Activities of compounds 3–7 and 10 against S. aureus (ATCC® 12,600™), methicillin-resistant S. aureus (ATCC®43,300™), B. subtilis (ATCC®6633™), E. coli (ATCC®10,536™) and C. albicans (ATCC®64,550™)

Compounds MIC [µg/mL]
S. aureus Methicillin Resistant
S. aureus 		B. subtilis E. coli C. albicans
Compound alone  + disulfiram 4 µg/mL
3 – 5 20 20 40 10
4 – 5 – – – –
5 40 5 – – – 40
6 – – – – – 40
7 – – – – – 40
10 – 5 – – – –
Chloramphenicol 6.25 2.5 12.5 6.25 3.12
Amphotericin B 0.62
Open in a new tab

–: not active at 80 μg/mL

Antiproliferative activity of the isolated compounds

Compounds 1–10 were further evaluated for their anti-proliferative activity against HT1080, T46D and A2780S cancer cell lines. Compounds 3 and 5–8 were active with IC50 values ranging from 2.48 to 29.17 μM (Table 2). A2780S was the most sensitive cancer cell line to these five active compounds (3 and 5–8). Compound 3 was the most potent molecule, which might explain why it was active against all the above-mentioned bacterial and fungal strains.

Table 2.

IC50 (μM) of compounds 1–10 against HT1080, T46D, and A2780S cell lines

Compound Effect on cell viability
HT1080 T46D A2780S
1  > 50  > 50  > 50
2  > 50  > 50  > 50
3 3.8 5.92 2.48
4  > 50  > 50  > 50
5 25.47 29.17 10.56
6 10.42 15.81 9.72
7 16.37 14.34 7.48
8 10.85 10.56 7.07
10  > 50  > 50  > 50
Paclitaxel 0.075 0.0045 0.0081
Open in a new tab

NF-κB inhibitory activity

When tested for TNF-α-induced NF-κB inhibitory activity, compounds 4, 6 and 8 were active with IC50 values of 26.45, 5.41 and 15.8 µM, respectively (Table 3). Compound 4 did not show any anti-proliferative activity at 50 µM, but inhibited NF-κB at 26.45 µM. In the absence of a cytotoxic response, inhibition of TNF-α-induced NF-κB activity suggests the potential of mediating a cancer chemopreventive response. It is interesting that both compounds 6 and 8 demonstrated anti-proliferative and anti-NF-κB activities.

Table 3.

IC50 (μM) of inhibition of NF-kB activity

Compound Inhibition of NF-κB activity
4 26.45
6 5.41
8 15.8
TPCA1 0.0145
Open in a new tab

Conclusion

This study reported the isolation and identification of compounds with antimicrobial, antiproliferative and NF-κB inhibitory potentials from Hawaiian fungus Aspergillus polyporicola. Their structures were unambiguously determined based on extensive HRESIMS data analysis, NMR spectroscopic interpretations, ECD studies, ECD and DFT energy calculation and single-crystal X-ray diffraction. Most of the isolated compounds (3–10) showed either antimicrobial or antiproliferative activity, or both. Interestingly, the anti-S. aureus activity of compound 5 was enhanced dramatically by disulfiram whereas compound 3 showed potent inhibitory activity against HT1080, T46D, and A2780S cell lines, and compound 6 demonstrated strong inhibition against NF-κB.

Supplementary Information

Below is the link to the electronic supplementary material.

Supplementary file1 (DOCX 5963 KB) (5.8MB, docx)

Acknowledgements

This work was financially supported by start-up funding from Daniel K. Inouye College of Pharmacy (DKICP), Seed Grants from University of Hawaii at Hilo (UH Hilo), and the Victoria S. and Bradley L. Geist Foundation (15ADVC-74420, 17CON-86295, and 20CON-102163) (to SC). Funding for this work was also supported by Hawaii IDeA Network for Biomedical Research Excellence III and IV (INBRE-III and INBRE-IV) project: NIGMS Grant 5P20GM103466. We would also like to express our gratitude to Mr. Justin Reinicke for his help with HRMS, NMR, optical rotation and ECD data collection.

Availability of data

Accession Number: GenBank (Accession Number CCDC 2026987 and CCDC 2026988).

Declarations

Conflict of interest

No conflict of interest was reported by the authors.

References

  1. Alvin A, Miller KI, Neilan BA. Exploring the potential of endophytes from medicinal plants as sources of antimycobacterial compounds. Microbiol Res. 2014;169:483–495. doi: 10.1016/j.micres.2013.12.009. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Aparicio-Cuevas MA, Rivero-Cruz I, Sánchez-Castellanos M, Menéndez D, Raja HA, Joseph-Nathan P, González MD, Figueroa M. Dioxomorpholines and derivatives from a marine-facultative Aspergillus species. J Nat Prod. 2017;80:2311–2318. doi: 10.1021/acs.jnatprod.7b00331. [DOI] [PubMed] [Google Scholar]
  3. Arai K, Rawlings BJ, Yoshizawa Y, Vederas JC. Biosyntheses of antibiotic A26771B by Penicilliumturbatum and dehydrocurvularin by Alternariacinerariae: comparison of stereochemistry of polyketide and fatty acid enoyl thiol ester reductases. J Am Chem Soc. 1989;111:3391–3399. doi: 10.1021/ja00191a042. [DOI] [Google Scholar]
  4. Bruker AXS (2016) APEX3, Madison, Wisconsin
  5. Chen M, Wang KL, Liu M, She ZG, Wang CY. Bioactive steroid derivatives and butyrolactone derivatives from a gorgonian-derived Aspergillus sp. fungus. Chem Biodiverse. 2015;12:1398–1406. doi: 10.1002/cbdv.201400321. [DOI] [PubMed] [Google Scholar]
  6. Dai J, Krohn K, Flörke U, Pescitelli G, Kerti G, Papp T, Kövér KE, Bényei AS, Draeger S, Schulz B, Kurtán T. Curvularin type metabolites from the fungus Curvularia sp. isolated from a marine alga. Eur J Org Chem. 2010;36:6928–6937. doi: 10.1002/ejoc.201001237. [DOI] [Google Scholar]
  7. de Castro MV, Ióca LP, Williams DE, Costa BZ, Mizuno CM, Santos MF, de Jesus K, Ferreira EL, Seleghim MH, Sette LD, Pereira Filho ER, Ferreira AG, Gonçalves NS, Santos RA, Patrick BO, Andersen RJ, Berlinck RGS. Condensation of macrocyclic polyketides produced by Penicillium sp. DRF2 with mercaptopyruvate represents a new fungal detoxification pathway. J Nat Prod. 2016;79:1668–1678. doi: 10.1021/acs.jnatprod.6b00295. [DOI] [PubMed] [Google Scholar]
  8. Dolomanov OV, Bourhis LJ, Gildea RJ, Howard JAK, Puschmann H. OLEX2: a complete structure solution, refinement and analysis program. J Appl Cryst. 2009;42:339–341. doi: 10.1107/S0021889808042726. [DOI] [Google Scholar]
  9. Fei-Zhang DJ, Li C, Cao S. Hawaii natural compounds are promising to reduce ovarian cancer deaths. Cancer Biol Ther. 2016;17:709–712. doi: 10.1080/15384047.2016.1178428. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Huang P, Li C, Sarotti AM, Turkson J, Cao S. Sphaerialactonam, a γ-lactam–isochromanone from the Hawaiian endophytic fungus Paraphaeosphaeria sp. FT462. Tetrahedron Lett. 2017;58:1330–1333. doi: 10.1016/j.tetlet.2017.02.052. [DOI] [Google Scholar]
  11. Kondratyuk TP, Park EJ, Yu R, VanBreemen RB, Asolkar RN, Murphy BT, Fenical W, Pezzuto J. Novel marine phenazines as potential cancer chemopreventive and anti-inflammatory agents. Mar Drugs. 2012;10:451–464. doi: 10.3390/md10020451. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Lai S, Shizuri Y, Yamamura S, Kawai K, Terada Y, Furukawa H. Novel curvularin-type metabolites of a hybrid strain ME 0005 derived from Penicilliumcitreo-viride B. IFO 6200 and 4692. Tetrahedron Lett. 1989;30:2241–2244. doi: 10.1016/S0040-4039(00)99658-8. [DOI] [Google Scholar]
  13. Li CS, Ding Y, Yang BJ, Miklossy G, Yin HQ, Walker LA, Turkson J, Cao S. A new metabolite with a unique 4-pyranone−γ-lactam–1,4-thiazine moiety from a Hawaiian-plant associated fungus. Org Lett. 2015;17:3556–3559. doi: 10.1021/acs.orglett.5b01650. [DOI] [PubMed] [Google Scholar]
  14. Li C, Yang B, Fenstemacher R, Turkson J, Cao S. Lycopodiellactone, an unusual δ-lactone-isochromanone from a Hawaiian plant-associated fungus Paraphaeosphaerianeglecta FT462. Tetrahedron Lett. 2015;56:1724–1727. doi: 10.1016/j.tetlet.2015.02.076. [DOI] [Google Scholar]
  15. Li CS, Ding Y, Yang BJ, Hoffman N, Yin HQ, Mahmud T, Turkson J, Cao S. Eremophilane sesquiterpenes from Hawaiian endophytic fungus Chaetoconis sp. FT087. Phytochemistry. 2016;126:41–46. doi: 10.1016/j.phytochem.2016.03.005. [DOI] [PubMed] [Google Scholar]
  16. Li CS, Ren G, Yang BJ, Miklossy G, Turkson J, Fei P, Ding Y, Walker LA, Cao S. Meroterpenoids with antiproliferative activity from a Hawaiian-plant associated fungus Peyronellaeacoffeae-arabicae FT238. Org Lett. 2016;18:2335–2338. doi: 10.1021/acs.orglett.6b00685. [DOI] [PubMed] [Google Scholar]
  17. Li C, Sarotti AM, Yang B, Turkson J, Cao S. A New N-methoxypyridone from the co-cultivation of Hawaiian endophytic fungi Camporesiasambuci FT1061 and Epicoccumsorghinum FT1062. Molecules. 2017;22:1166. doi: 10.3390/molecules22071166. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Li C, Hu Z, Liu Q, Wu X, Cao S. Two new tricycloalternarenes from Hawaiian endophytic fungus Didymella sp. FT433. Tetrahedron Lett. 2018;59:3381–3383. doi: 10.1016/j.tetlet.2018.07.061. [DOI] [Google Scholar]
  19. Li C, Sarotti AM, Yoshida W, Cao S. Two new polyketides from Hawaiian endophytic fungus Pestalotiopsis sp. FT172. Tetrahedron Lett. 2018;59:42–45. doi: 10.1016/j.tetlet.2017.11.045. [DOI] [Google Scholar]
  20. Li C, Sarotti AM, Wu X, Yang B, Turkson J, Chen Y, Liu Q, Cao S. An unusual benzoisoquinoline-9-one derivative and other related compounds with antiproliferative activity from Hawaiian endophytic Fungus Peyronellaea sp. FT431. Molecules. 2019;24:196. doi: 10.3390/molecules24010196. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Liang Q, Sun Y, Yu B, She X, Pan X. First total syntheses and spectral data corrections of 11-α-methoxycurvularin and 11-β-methoxycurvularin. J Org Chem. 2007;72:9846–9849. doi: 10.1021/jo701885n. [DOI] [PubMed] [Google Scholar]
  22. Lin ZJ, Zhang GJ, Zhu TJ, Liu R, Wei HJ, Gu QQ. Bioactive cytochalasins from Aspergillus flavipes, an endophytic fungus associated with the mangrove plant Acanthus ilicifolius. Helv Chim Acta. 2009;92:1538–1544. doi: 10.1002/hlca.200800455. [DOI] [Google Scholar]
  23. Martinez-Klimova E, Rodríguez-Peña K, Sánchez S. Endophytes as sources of antibiotics. Biochem Pharmacol. 2017;134:1–17. doi: 10.1016/j.bcp.2016.10.010. [DOI] [PubMed] [Google Scholar]
  24. Newman DJ, Cragg GM. Natural products as sources of new drugs over the nearly four decades from 01/1981 to 09/2019. J Nat Prod. 2020;83:770–803. doi: 10.1021/acs.jnatprod.9b01285. [DOI] [PubMed] [Google Scholar]
  25. Sheldrick GM. SHELXT—integrated space-group and crystal-structure determination. Acta Cryst. 2015;A71:3–8. doi: 10.1107/S2053273314026370. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Spek AL. Structure validation in chemical crystallography. Acta Crystallogr Sect D. 2009;65:148–155. doi: 10.1107/S090744490804362X. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Thom C, Church MB. The Aspergilli. Baltimore: Williams & Wilkins Comp; 1926. pp. 1–272. [Google Scholar]
  28. Vadlapudi V, Borah N, Yellusani KR, Gade S, Reddy P, Rajamanikyam M, Vempati LNS, Gubbala SP, Chopra P, Upadhyayula SM, Amanchy R. Aspergillus secondary metabolite database, a resource to understand the secondary metabolome of Aspergillus genus. Sci Rep. 2017;7:7325. doi: 10.1038/s41598-017-07436-w. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Wang F, Hu Z, Li C, Wu X, Cao S. Circumdatin M, a new benzodiazepine alkaloid with a unique pyrimidone-4-pyrone moiety from a Hawaiian marine fungus Aspergillus sp. Tetrahedron Lett. 2019;60:1724–1726. doi: 10.1016/j.tetlet.2019.05.061. [DOI] [Google Scholar]
  30. Wang C, Wu X, Bai H, Zaman KA, Hou S, Saito J, Wongwiwatthananukit S, Kim HS, Cao S. Antibacterial and NF-κB inhibitory lumazine peptides, aspochalasin, γ-butyrolactone derivatives, and cyclic peptides from a Hawaiian Aspergillus flavipes. J Nat Prod. 2020;83:2233–2240. doi: 10.1021/acs.jnatprod.0c00344. [DOI] [PubMed] [Google Scholar]
  31. Wang F, Sarotti AM, Jiang G, Huguet-Tapia JC, Zheng SL, Wu X, Li C, Ding Y, Cao S. Waikikiamides A-C: Complex diketopiperazine dimer and diketopiperazine–polyketide hybrids from a Hawaiian marine fungal strain Aspergillus sp. FM242. Org Lett. 2020;22:4408–4412. doi: 10.1021/acs.orglett.0c01411. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Zaman KA, Hu Z, Wu X, Cao S. Tryptoquivalines W and X, two new compounds from a Hawaiian fungal strain and their biological activities. Tetrahedron Lett. 2020;61:151730. doi: 10.1016/j.tetlet.2020.151730. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Zaman KA, Hu Z, Wu X, Hou S, Saito J, Kondratyuk TP, Pezzuto JM, Cao S. NF-κB inhibitory and antibacterial helvolic and fumagillin derivatives from Aspergillus terreus. J Nat Prod. 2020;83:730–737. doi: 10.1021/acs.jnatprod.9b01190. [DOI] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplementary file1 (DOCX 5963 KB) (5.8MB, docx)

Data Availability Statement

Accession Number: GenBank (Accession Number CCDC 2026987 and CCDC 2026988).

Articles from 3 Biotech are provided here courtesy of Springer

RESOURCES