Exploitation of Marine Resources

Alkaloids from the Jellyfish-Derived Fungus Aspergillus fumigatus SCSIO41214

  • YANG Bin ,
  • SALENDRA Limbadri ,
  • LIU Juan ,
  • LIU Yonghong
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  • CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
LIU Yonghong. email:

Copy editor: YAO Yantao

Received date: 2022-09-16

  Revised date: 2022-10-08

  Online published: 2022-10-13

Supported by

National Natural Science Foundation of China(21977102)

Guangdong-Joint Foundation of Shenzhen(2021B1515120046)

Abstract

Eight known alkaloids were isolated from jellyfish-derived fungus Aspergillus fumigatus SCSIO41214. These compounds were isolated by silica gel column chromatography, ostade-cylsilane (ODS), and high performance liquid chromatography (HPLC). The structure of 1 was identified by performing a comprehensive analysis of spectroscopic data and X-ray diffraction for the first time. The structures of 2 ~ 8 were elucidated by spectroscopic methods and by comparison with data from the literature. In bioassay, compound 4 showed weak inhibitory activity against lipopolysaccharide (LPS)-induced nitric oxide (NO) in RAW264.7 cells at the concentration of 10 μmol·L-1.

Cite this article

YANG Bin , SALENDRA Limbadri , LIU Juan , LIU Yonghong . Alkaloids from the Jellyfish-Derived Fungus Aspergillus fumigatus SCSIO41214[J]. Journal of Tropical Oceanography, 2023 , 42(4) : 195 -201 . DOI: 10.11978/2022193

1 Introduction

Marine symbiotic and epiphyte microorganisms are widely recognized as rich sources for the discovery of structurally novel and biologically active natural products. However, only few studies have focused on isolation of small-molecule natural products from jellyfish-associated microoraganisms, which are also recognized as a productive resource of bioactive molecules (Wang et al, 2015; Li et al, 2021; Li et al, 2022). The giant Nemopilema nomurai, which causes serious damage, inducing outbreaks in China’s coastal waters and even death of tourists for stinging, is one of the most widely distributed venomous jellyfish (Yue et al, 2015). In our preliminary study, several fungus strains obtained from giant jellyfish N. nomurai are investigated. Several relevant metabolites, including penicillixanthone A, displayed potent anti-HIV-1 activity by inhibiting infection against CCR5-tropic HIV-1 SF162, CXCR4-tropic HIV-1 NL4-3 (Tan et al, 2019) and fumigatosides B-D, and represented the first examples of glycosidated fumiquinzoline-type alkaloids from nature (Liu et al, 2015), have been isolated. As part of our ongoing investigation into the unique and bioactive natural products from jellyfish derived fungus, a strain identified as Aspergillus fumigatus SCSIO41214 was studied, which led to the isolation of eight known compounds (Fig. 1). Their structures were elucidated on the basis of extensive NMR spectroscopic data analysis, and X-ray single-crystal diffraction. Compounds 1 ~ 8 were tested for their inhibitory activities against LPS-induced NO production in RAW 264.7 cells.
Fig. 1 Structures of compounds 1

2 Results and discussion

Compound 1 was isolated as a white crystal. Its molecular formula was established to be C23H22N4O5 by HRESIMS peak at m/z 457.1484 [M+Na]+ (calcd. for C23H22NaN4O5 457.1482), indicating 15 degree unsaturation. The 1H NMR spectrum of 1 showed a methyl at δH 1.61 (d, J=6.5Hz, H-12), a methoxyl at δH 3.17 (s, H-27), three oxygenated/nitrogenated methines at δH 5.92 (s, H-14), 5.61 (s, H-2), 4.63 (q, J=7.0Hz, H-11), nine olefinic protons ranging from δH 7.26 to 8.29. The 13CNMR, and DEPT spectroscopic data of 1 showed 23 carbon signals, including one methyl, one methoxyl, one methylene, twelve methines (i.e., nine olefinic carbons and three nitrogenated carbons), and eight quaternary carbons (i.e., one oxygenated carbon, three carbonyls, and four olefinic carbons). By the HSQC spectrum, all proton resonances were unambiguously assigned to their respective carbons. Its 1D and 2D NMR spectra of 1 were almost the same as those of chaetominine (2) (Jiao et al, 2006). The distinction was attributed to the presence of a methoxyl group of 1, as which is evident from its molecular weight, to be 14 amu more than that of the known analogue, as well as in its NMR spectra. Further COSY correlation and HMBC correlations from CH3-27 to C-10, and CH3-12 to C-10, and C-11 confirmed the planar structure of 1, which was confirmed by its single-crystal X-ray crystallographic analysis (Fig. 2). The achievable precision of the Flack parameter (0.5 (3)) for 1 is limited, which could only support the determination of the relative configurations as 2S*, 3S*, 11R* and 14R*. Consequently, the structure of 1 was determined and named as fumuquinazoline K. Fumuquinazoline K has been reported that it was able to prevent the conformation of the winged-helix domain of the methyl methanesulfonate and ultraviolet-sensitive 81 (ωMUS81) via forming a strong binding affinity to the enzyme via perturbation approach (Ngo et al, 2021). However, its structure, including the relative configurations of the stereogenic carbons, was firstly elucidated based on spectroscopic analysis and the X-ray data.
Fig. 2 Selected 1H-1H COSY, HMBC correlations and X-ray crystallographic structure of 1
Additionally, the structures of other known compounds, chaetominine (2) (Jiao et al, 2006), 3'-(4-oxoquinazolin-3-yl) spiro[5'-oxolane]-2, 2'-dione (3) (Buttachon et al. 2012), fumiquinazoline J (4) Zhang et al, 2011; Yang et al, 2013 ), fumitremorgin C (5) (Wang et al, 2019), spirotryprostatin A (6) (Cui et al, 1996; Wang et al, 2019), brevianamide F (7) (Son et al, 2007), cyclo-(L-Pro-L-Tyr) (8) (Jayatilake et al, 1996) were also isolated and identified by using their NMR and MS data, and comparing these data with those reported in the literature. This is the first report of these compounds from the jellyfish associated fungus.
The anti-inflammatory activities of the isolated metabolites were also evaluated on the basis of their inhibition effects of NO production in the LPS induced mouse macrophage RAW264.7 cells. At a concentration of 10μM, compound 4 showed inhibitory abilities with inhibitory rates at 28.5%, while the positive control LNMMA showed inhibition rate at 31.1%. Other compounds showed no inhibition activities.

3 The physicochemical data of the compounds

Fumuquinazoline K (1): HR ESI-MS m/z 435.1670 [M+H]+ (calcd. for C23H23N4O5 435.1663); 457.1484 [M+Na]+ (calcd. for C23H22NaN4O5 457.1482); α D 2 5-3.5° (0.1, c, MeOH); UV (MeOH) λmax (log ε): 210 (0.74), 230 (0.52) nm; IR (film) vmax: 3356, 1724, 1666, 1608, 1479cm-1; 1H NMR (500MHz, DMSO-d6) δ: 8.29 (1H, s, H-25), 8.18 (1H, s, H-19), 7.88 (1H, td, J=8.5, 1.5Hz, H-21), 7.70 (1H, d, J=8.0Hz, H-22), 7.59 (1H, t, J=7.5Hz, H-20), 7.51 (1H, d, J=8.0Hz, H-8), 7.50 ( 1H, d, J=7.5Hz, H-5), 7.44 (1H, td, J=7.5, 1.0Hz, H-7), 7.26 (1H, td, J=7.5, 1.0Hz, H-6), 5.92 (1H, s, H-14), 5.61 (1H, s, H-2), 4.63 (1H, q, J=7.0Hz, H-11), 3.17 (3H, s, H-27), 2.96 (1H, t, J=7.5Hz, H-13a), 2.54 (1H, m, H-13b), 1.61 (3H, d, J=6.5Hz, H-12). 13C NMR (125MHz, DMSO-d6) δ: 172.0 (C, C-10), 165.7 (C, C-17), 160.0 (C, C-15), 147.4 (C, C-23), 146.6 (C, C-25), 138.7 (C, C-9), 136.7 (C, C-4), 134.7 (CH, C-21), 129.9 (CH, C-7), 127.3 (CH, C-20), 127.2 (CH, C-22), 126.4 (CH, C-19), 125.5 (CH, C-6), 124.9 (CH, C-5), 121.2 (C, C-18), 114.5 (CH, C-8), 82.5 (CH, C-2), 76.4 (C, C-3), 59.8 (CH, C-14), 50.4 (CH, C-11), 48.6 (CH3, C-27), 39.0 (CH2, C-13), 14.0 (CH3, C-12).
X-ray crystal data for compound 1: chemical formulae C23H24N4O6, F.W=434.44, white color crystals, 0.15×0.11×0.1mm3, trigonal, space group: P3121, Å, a=10.7396 (4) Å, b=10.7396 (4) Å, c=35.6809 (12) Å, α=β=90°, γ=120°. V=3564.0 (3) Å3, Z=6, Dc=1.214g/cm3, F(000)=1368.0, Cu Kα radiation, λ=1.54184, θ range for data collection: 7.432 to 148.206°; 8851 reflections collected, 4382 unique (Rint=0.0564), the structure was refined by full-matrix least-squares on F2. Final GoF=1.047. Final R indexes [I>2σ (I)]: R1=0.0793, wR2=0.2256. Final R indexes (all data) R1=0.0.0846, wR2=0.2360; Flack Parameters=-0.5 (3); Largest diff. peak and hole: 0.48 and -0.48eÅ-3. Data were collected on Agilent Xcalibur Nova single-crystal diffractometer using Cu Kα radiation. The crystal structure was refined by full-matrix least-squares calculation. Crystallographic data for the structure of 1 have been deposited in the Cambridge Crystallographic Data Centre (deposition number: CCDC 1847139).
Chaetominine (2): ESI-MS m/z: 403 [M+H]+; 1H NMR (700MHz, CD3OD) δ: 8.23 (1H, brs, H-24), 8.13 (1H, s, H-19), 7.81 (1H, t, J=7.7Hz, H-21), 7.70 (1H, d, J=7.5Hz, H-22), 7.52 (1H, t, J=7.0Hz, H-20), 7.45 (1H, d, J=8.4Hz, H-5), 7.37 (1H, t, J=7.7Hz, H-8), 7.20 (1H, t, J=7.7Hz, H-6), 5.88 (1H, s, H-12), 5.55 (1H, s, H-2), 4.55 (1H, q, J=14.0, 6.3Hz, H-24), 2.88 (1H, t, J=12.6Hz, H-13a), 2.47 (1H, d, J=11.9Hz, H-13b), 1.55 (1H, d, J=2.8Hz, H-26). 13C NMR (150MHz, CD3OD) δ: 172.0 (C, C-25), 165.6 (C, C-15), 160.0 (C, C-11), 147.4 (C, C-23), 146.8 (C, C-21), 138.7 (C, C-9), 134.7 (CH, C-4, C-19), 129.9 (CH, C-7), 127.3 (CH, C-17), 127.2 (CH, C-18), 126.4 (CH, C-20), 125.5 (CH, C-6), 124.9 (CH, C-5), 120.9 (C, C-16), 114.5 (CH, C-8), 82.5 (CH, C-2), 76.4 (C, C-3), 59.6 (CH, C-24), 50.1 (CH, C-14), 38.2 (CH2, C-13), 14.0 (CH3, C-12).
3'-(4-oxoquinazolin-3-yl) spiro[5'-oxolane]-2, 2'-dione (3): Pale yellow oil; ESI-MS m/z: 348 [M+H]+; 1H NMR (700MHz, CDCl3) δ: 8.64 (1H, s, H-22), 8.29 (1H, d, J=7.7Hz, H-16), 7.90 (1H, t, J=7.7Hz, H-18), 7.77 (1H, d, J=7.0Hz, H-5), 7.76 (1H, d, J=8.6Hz, H-19), 7.75 (1H, d, J=7.7Hz, H-17), 7.40 (1H, t, J=7.7Hz, H-7), 7.19 (1H, t, J=7.7Hz, H-6), 7.02 (1H, d, J=7.7Hz, H-8), 5.70 (1H, t, J=10.5Hz, H-11), 3.25 (1H, dd, J=14.0, 10.5Hz, H-12a), 3.11 (1H, dd, J=14.0, 4.2Hz, H-12b). 13C NMR (150MHz, CDCl3) δ: 175.4 (C, C-2), 171.1 (C, C-10), 160.1 (C, C-14), 147.2 (CH, C-22), 147.2 (C, C-20), 142.6 (C, C-9), 134.6 (CH, C-18), 131.4 (CH, C-7), 127.6 (CH, C-17), 127.3 (CH, C-19), 126.7 (C, C-4), 126.1 (CH, C-16), 125.4 (CH, C-5), 123.1 (CH, C-6), 121.9 (C, C-15), 110.5 (CH, C-8), 80.7 (C, C-3), 57.2 (CH, C-11), 33.7 (CH2, C-12).
Fumiquinazoline J (4): ESI-MS m/z: 357 [M+H]+; 1H NMR (700MHz, DMSO-d6) δ: 9.58 (1H, s, H-19), 8.15 (1H, dd, J=8.0, 1.0Hz, H-10), 7.81 (1H, td, J=7.8, 7.3Hz, H-8), 7.64 (1H, d, J=8.0Hz, H-7), 7.53 (1H, td, J=7.8, 7.5Hz, H-9), 7.41 (1H, d, J=8.0Hz, H-24), 7.38 (1H, d, J=8.5Hz, H-21), 7.11 (1H, td, J=8.0, 7.0Hz, H-22), 7.00 (1H, td, J=7.5, 7.0Hz, H-22), 5.71 (1H, br, H-14), 3.44 (1H, dd, J=17.5, 3.5Hz, H-15a), 3.24 (1H, dd, J=18.0, 4.5Hz, H-15b), 2.12 (3H, s, H-16). 13C NMR (150MHz, DMSO-d6) δ: 169.2 (C, C-1), 159.4 (C, C-12), 154.4 (C, C-4), 146.7 (C, C-6), 134.9 (CH, C-8), 134.0 (C, C-18, C-20), 127.4 (CH, C-7, C-9), 127.3 (C, C-25), 126.4 (CH, C-10), 122.3 (CH, C-22), 120.2 (C, C-11), 119.4 (CH, C-23), 118.2 (CH, C-24), 111.8 (CH, C-21), 105.6 (C, C-17), 54.6 (C, C-3), 54.2 (CH, C-14), 25.6 (CH2, C-15), 18.4 (CH3, C-16).
Fumitremorgin C (5): ESI-MS m/z: 380 [M+H]+; 1H NMR (700MHz, CDCl3) δ: 7.94 (1H, s, H-1), 7.43 (1H, d, J=8.6Hz, H-16), 6.85 (1H, d, J=2.1Hz, H-19), 6.82 (1H, d, J=9.1Hz, H-17), 5.98 (1H, d, J=9.5Hz, H-3), 4.83 (1H, m, H-6), 4.18 (1H, dd, J=11.6, 4.9Hz, H-6), 4.05 (1H, m, H-12), 3.83 (3H, s, OCH3-18), 3.60 (2H, m, H-9), 3.44 (2H, m, H-15), 3.10 (dd, J=15.8, 11.6Hz, H-13), 2.34 (1H, m, H-7a), 2.23 (1H, d, J=1.9Hz, H-7b), 2.06 (1H, dd, J=7.2, 4.1Hz, H-8a), 1.94 (1H, d, J=8.7Hz, H-8b), 1.94 (3H, d, J=0.8Hz, H-23), 1.64 (3H, d, J=0.8Hz, H-24). 13C NMR (150MHz, CDCl3) δ: 169.6 (C, C-5), 165.8 (C, C-11), 156.5 (C, C-18), 137.1 (C, C-20), 134.0 (C, C-22), 132.2 (C, C-2), 124.2 (CH, C-21), 120.8 (C, C-15), 118.9 (CH, C-16), 109.5 (CH, C-17), 106.2 (C, C-14), 95.3 (CH, C-19), 59.3 (CH, C-6), 56.8 (CH, C-12), 55.8 (CH3, C-25), 51.0 (CH, C-3), 45.4 (CH2, C-9), 30.6 (CH2, C-7), 28.6 (CH2, C-7), 25.7 (CH3, C-23), 23.1 (CH2, C-8), 22.0 (CH2, C-13), 18.1 (CH3, C-24).
Spirotryprostatin A (6): ESI-MS m/z: 396 [M+H]+; 1H NMR (700MHz, CD3OD) δ: 7.04 (1H, d, J=8.4Hz, H-4), 6.56 (1H, dd, J=8.4, 2.1Hz, H-5), 6.50 (1H, d, J=2.1Hz, H-7), 5.11 (1H, dt, J=9.1, 1.4Hz, H-19), 5.04 (1H, dd, J=12.5, 7.7Hz, H-9), 4.73 (1H, d, J=9.1Hz, H-18), 4.45 (1H, t, J=7.7Hz, H-12), 3.80 (3H, s, OMe-6), 3.57 (1H, m, H-15), 2.61 (1H, dd, J=13.3, 9.5Hz, H-8a), 2.35 (1H, dd, J=13.3, 10.1Hz, H-8b), 2.33 (1H, m, H-13a), 2.14 (1H, m, H-13b), 2.06 (1H, m, H-14a), 2.03 (1H, m, H-14b), 1.67 (3H, d, J=0.7Hz, H-21), 1.20 (3H, d, J=8.4Hz, H-22). 13C NMR (150MHz, CD3OD) δ: 183.2 (C, C-2), 169.5 (C, C-11), 168.9 (C, C-17), 162.2 (C, C-6), 144.4 (C, C-7a), 139.1 (C, C-20), 128.2 (CH, C-4), 122.7 (CH, C-19), 120.1 (C, C-3a), 107.7 (CH, C-5), 97.7 (CH, C-7), 62.3 (CH, C-9), 61.8 (CH, C-12), 59.8 (CH, C-18), 57.1 (C, C-3), 55.9 (C, OCH3-6), 46.2 (CH2, C-14), 35.3 (CH2, C-8), 28.5 (CH2, C-13), 25.6 (CH3, C-22), 24.5 (CH2, C-15), 18.1 (CH3, C-21).
Brevianamide F (7): ESI-MS m/z: 284 [M+H]+; α D 2 5-75.3° (c 0.1 MeoH); 1H NMR (500MHz, CD3OD) δ: 7.75 (1H, s, NH-1), 7.58 (1H, d, J=8.0Hz, H-4), 7.34 (1H, d, J=8.0Hz, H-7), 7.12 (1H, d, J=2.0Hz, C-2), 7.07 (1H, t, J=7.5Hz, H-6), 6.98 (1H, t, J=7.5Hz, H-5), 4.32 (1H, t, J=5.0Hz, H-9), 4.09 (1H, t, J=8.5Hz, H-12), 3.32 (1H, m, H-15a), 3.23 (2H, m, H-15b, H-8a), 3.09 (1H, dd, J=14.5, 5.5Hz, H-8b), 1.99 (1H, m, H-14a), 1.68 (1H, m, H-14b), 1.61 (1H, m, H-13a), 1.40 (1H, m, H-13b). 13C NMR (125MHz, CD3OD) δ: 169.0 (C, C-11), 165.5 (C, C-17), 135.9 (C, C-7a), 127.3 (C, C-3a), 124.4 (CH, C-2), 120.8 (CH, C-6), 118.6 (CH, C-4), 118.2 (CH, C-5), 111.2 (CH, C-7), 109.2 (C, C-3), 58.4 (CH, C-12), 55.2 (CH, C-9), 44.6 (CH2, C-15), 27.6 (CH2, C-14), 25.8 (CH2, C-8), 21.8 (CH2, C-13).
Cyclo-(L-Pro-L-Tyr) (8): ESI-MS m/z: 261 [M+H]+; α D 2 5-51.2° (c 0.2 MeoH); 1H NMR (500MHz, CD3OD) δ: 7.28 (1H, s, NH-2), 7.09 (2H, d, J=7.5Hz, H-12, H-16), 6.81 (2H, d, J=7.5Hz, H-13, H-15), 5.89 (1H, s, NH-8), 4.25 (1H, dd, J=9.5, 2.0Hz, H-9), 4.12 (1H, t, J=8.0Hz, H-6), 3.67 (1H, m, H-3a), 3.61 (1H, m, H-3b), 3.52 (1H, dd, J=15.0, 4.0Hz, H-10a), 2.82 (1H, dd, J=14.5, 10.0Hz, H-10b), 2.38 (1H, m, H-5a), 2.04 (1H, m, H-4a), 1.96 (1H, m, H-5b), 1.94 (1H, m, H-4b). 13C NMR (125MHz, CD3OD) δ: 169.7 (C, C-7), 165.2 (C, C-1), 155.6 (C, C-14), 130.3 (CH, C-12, C-16), 127.0 (C, C-11), 116.1 (CH, C-13, C-15), 59.2 (CH, C-6), 56.3 (CH, C-9), 45.5 (CH2, C-3), 35.9 (CH2, C-10), 28.4 (CH2, C-5), 22.5 (CH2, C-4).

4 Experiment

4.1 General experimental procedures

The NMR spectra was measured with a Bruker-AC500 or AVANCE-III-HD700 NMR spectrometer with TMS as an internal standard. HR-ESI-MS data was recorded on a Bruker micro-TOF-QII mass spectrometer. Optical rotations were recorded on an Anton Paar MCP500 polarimeter. CD spectra was recorded with a Chirascan circular dichroism spectrometer (Applied Photophysics). UV spectra was obtained on a Shimadzu UV-2401PC spectrophotometer (Shimadzu Corporation, Kyoto, Japan). Semi-preparative HPLC was performed on HTACHI L2000 and HTACHI L2130 with YMC ODS SERIES (YMC-pack ODS-A, YMC Co., Ltd., 10mm×250mm, 5µm, Kyoto, Japan). YMC gel (ODS-A, 12nm, S-50µm) was used for column chromatography. The silica gel GF254 used for TLC was supplied by the Qingdao Marine Chemical Factory, Qingdao, China.

4.2 Fungal material

Aspergillus fumigatus SCSIO41214 (Original Number: J08NF-8) was isolated from the jellyfish Nemopilema nomurai collected off the southern coast of Korea in June 2007 and identified by Dr. K.S. Bae. The specimen was identified by Dr. Xiuping Lin. The strain was deposited in the RNAM Center, South China Sea Institute of Oceanology, Chinese Academy of Sciences.

4.3 Extraction and isolation

The strain SCSIO41214 was cultured on MA agar plates (malt extract: 25g, agar: 15g, sea salt: 10g, distilled water: 1L and pH: 7.4~7.8) and incubated for 5 days at 28℃. MA seed medium (malt extract: 25g, sea salt: 10g, distilled water: 1L and pH: 7.4~7.8) in 150mL Erlenmeyer flasks was inoculated with the fungus and incubated at 25℃ for 3 days on a rotating shaker (180r·min-1). Autoclaved rice solid-substrate medium in 1000 mL flasks (rice 220g, sea salt 6.6g, water 220mL) was inoculated with 10 mL seed solution. Flasks were incubated at 25℃ in a static position. After 45 days, cultures from 62 flasks were harvested for the isolation of substances. The obtained solid culture was crushed and extracted with twice the amount of acetone three times. The acetone extract was evaporated under reduced pressure to afford an aqueous solution, which was extracted with twice the amount of EtOAc to yield a crude gum.
The EtOAc portion (140g) was subsequently separated by silica gel column chromatography using Petroleum ether/EtOAc/MeOH (v/v/v, 100:0:0, 50:50:0, 0:0:100) gradient elution to give twenty-one fractions (Frs. 1-21). Fr.8 was subjected to ODS gel column chromatography, using a gradient of MeOH (10%~100%) in H2O, to give 17 fractions (Frs. 8-1~8-17). Frs.8-8 was purified by semi-preparative RP-HPLC (60%MeOH in H2O) at a flow rate of 3mL·min-1 to afford 8 (28.6mg, τR=29.1min). Frs.8-9 was purified by semi-preparative RP-HPLC (65%MeOH in H2O) at a flow rate of 3mL·min-1 to afford 7 (12.6mg, τR=34.0min). Fr.11 was subjected to ODS gel column chromatography, using a gradient of MeOH (10%→100%) in H2O, to get 20 fractions (Frs. 11-1~11-20). Frs.11-14 was purified by semi-preparative RP-HPLC (45%MeOH in H2O) at a flow rate of 3mL·min-1 to yield 4 (4.2mg, τR=30.2min). Frs.11-15 was purified by semi-preparative RP-HPLC (40%MeCN in H2O) at a flow rate of 3mL·min-1 to offer 5 (1.30mg, τR=25.2min). Fr.13 was subjected to ODS gel column chromatography, using a gradient of MeOH (10%~100%) in H2O, to acquire 16 fractions (Frs. 13-1~13-19). Frs.13-9 was purified by semi-preparative RP-HPLC (45%MeOH in H2O) at a flow rate of 3mL·min-1 to obtain 1 (10.0mg, τR=37.5min). Frs.13-10 was separated on Sephadex LH-20 eluted with CH2Cl2-MeOH (v/v, 1:1) and then purified by semi-preparative RP-HPLC (53%MeOH in H2O) at a flow rate of 3mL·min-1 to provide 3 (9mg, τR=23.2min), 6 (5.6mg, τR=34.5min). Frs.13-12 was purified by semi-preparative RP-HPLC (40%MeOH in H2O) at a flow rate of 3mL·min-1 to offer 2 (37mg, τR=31.0min).

4.4 NO production inhibitory assay

The nitric oxide assay of 1 ~ 8 was performed using the Griess method in vitro in 24-well plates as previously described (Long et al, 2022).

5 Conclusion

In our search for fungus Aspergillus fumigatus SCSIO41214 from the jellyfish Nemopilema nomurai, collected off the southern coast of Korea, eight known alkaloids, fumuquinazoline K (1), chaetominine (2), 3'-(4-oxoquinazolin-3-yl) spiro[5'-oxolane]-2, 2'-dione (3), fumiquinazoline J (4), fumitremorgin C (5), spirotryprostatin A (6), brevianamide F (7), cyclo-(L-Pro-L-Tyr) (8), were isolated. Their structures were determined by extensive spectroscopic analysis. Among them, compound 4 showed weak anti-inflammatory activity at 10 μM. This research enriches the chemical libraries of jellyfish-derived fungus and provides a basis for developing new drugs.
[1]
王亚楠, 高海, 丁健, 等, 2019. 红树林来源耐酸真菌Aspergillus fumigatus OUCMDZ-5210次生代谢产物的研究[J]. 中国海洋药物, 38(5): 47-53.

WANG YANAN, GAO HAI, DING JIAN, et al, 2019. Studies on secondary metabolite of aciduric fungus Aspergillus fumigatus OUCMDZ-5210 derived from Thailand mangrove[J]. Chinese Journal of Marine Drugs, 38(5): 47-53 (in Chinese with English abstract).

[2]
杨勇勋, 董小萍, 晏永明, 等, 2013. 白三叶草植物内生真菌烟曲霉及其次生代谢产物的研究[J]. 天然产物研究与开发, 25(1): 64-67.

YANG YONGXUN, DONG XIAOPING, YAN YONGMING, et al, 2013. Studies on secondary metabolites produced by endophytic Aspergillus fumigatus from Trifolium repens[J]. Natural Product Research and Development, 25(1): 64-67 (in Chinese with English abstract).

[3]
张丽敏, 李占林, 白皎, 等, 2011. 真菌Aspergillus sp. HT-2次级代谢产物的研究[J]. 中国药学杂志, 46(15): 1154-1158.

ZHANG LIMIN, LI ZHANLIN, BAI JIAO, et al, 2011. Metabolites of Aspergillus sp. HT-2[J]. Chinese Pharmaceutical Journal, 46(15): 1154-1158 (in Chinese with English abstract).

[4]
BUTTACHON S, CHANDRAPATYA A, MANOCH L, et al, 2012. Sartorymensin, a new indole alkaloid, and new analogues of tryptoquivaline and fiscalins produced by Neosartorya siamensis (KUFC 6349)[J]. Tetrahedron, 68(15): 3253-3262.

DOI

[5]
CUI CHENBIN, KAKEYA H, OSADA H, 1996. Novel mammalian cell cycle inhibitors, spirotryprostatins A and B, produced by Aspergillus fumigatus, which inhibit mammalian cell cycle at G2/M phase[J]. Tetrahedron, 52(39): 12651-12666.

DOI

[6]
JAYATILAKE G S, THORNTON M P, LEONARD A C, et al, 1996. Metabolites from an Antarctic sponge-associated bacterium, Pseudomonas aeruginosa[J]. Journal of Natural Products, 59(3): 293-296.

DOI

[7]
JIAO RUIH, XU SHU, LIU JUNY, et al, 2006. Chaetominine, a cytotoxic alkaloid produced by endophytic Chaetomium sp IFB-E015[J]. Organic Letters, 8(25): 5709-5712.

DOI

[8]
LI DAN-DAN, WANG YING, KIM E L, et al, 2021. Neuroprotective effect of cyclo-(L-Pro-L-Phe) isolated from the jellyfish-derived fungus Aspergillus flavus[J]. Marine Drugs, 19(8): 417.

DOI

[9]
LI DAN-DAN, WANG YING, KIM E L, et al, 2022. A new fungal triterpene from the fungus Aspergillus flavus Stimulates glucose uptake without fat accumulation[J]. Marine Drugs, 20(3): 203.

DOI

[10]
LIU JUAN, WEI XIAOYI, KIM E L, et al, 2015. New glucosidated pyrazinoquinazoline indole alkaloids from fungus Aspergillus fumigatus derived of a jellyfish[J]. Tetrahedron, 71(2): 271-275.

DOI

[11]
LONG JIEYI, PANG XIAOYAN, LIN XIUPING, et al, 2022. Asperbenzophenone A and Versicolamide C, new fungal metabolites from the soft coral derived Aspergillus sp. SCSIO 41036[J]. Chemistry & Biodiversity, 19(3): e202100925.

[12]
NGO S T, VU K B, PHAM M Q, et al, 2021. Marine derivatives prevent wMUS81 in silico studies[J]. Royal Society Open Science, 8(9): 210974.

DOI

[13]
SON B W, ZHANG DAHAI, NOVIENDRI D, et al, 2007. 12, 13-Dihydroxyfumitremorgin C, fumitremorgin C, and brevianamide F, antibacterial diketopiperazine alkaloids from the marine-derived fungus Pseudallescheria sp[J]. Natural Product Sciences, 13(3): 251-254.

[14]
TAN SUIYI, YANG BIN, LIU JUAN, et al, 2019. Penicillixanthone A, a marine-derived dual-coreceptor antagonist as anti-HIV-1 agent[J]. Natural Product Research, 33(10): 1467-1471.

DOI PMID

[15]
WANG HAIBO, HONG J, YIN JUN, et al, 2015. Dimeric octaketide spiroketals from the Jellyfish-derived fungus Paecilomyces variotii J08NF-1[J]. Journal of Natural Products, 78(11): 2832-2836.

DOI

[16]
YUE YANG, YU HUAHUA, LI RONGFENG, et al, 2015. Exploring the antibacterial and antifungal potential of jellyfish-associated marine fungi by cultivation-dependent approaches[J]. Plos One, 10(12): e0144394.

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