Ochratoxin compound with activity of resisting aquatic pathogenic bacteria as well as preparation method and application of ochratoxin compound

Abstract

The invention discloses an ochratoxin compound with aquatic pathogenic bacterium resisting activity and a preparation method and application thereof, the ochratoxin compound is characterized in that the structural formula of the compound is shown as I, and the preparation method comprises the following steps: firstly, obtaining a fermentation product of marine fungi through fermentation culture; soaking the fermented product with ethyl acetate, and extracting to obtain a crude extract; the preparation method comprises the following steps: firstly, preparing a crude extract, then separating and purifying the crude extract by using normal-phase silica gel column chromatography, reverse medium-pressure column chromatography and reversed-phase semi-preparative high performance liquid chromatography to finally obtain the target ochratoxin, and the target ochratoxin has the advantages that the target ochratoxin has a remarkable effect of resisting the activity of aquatic pathogenic bacteria and can be used for research and development of drugs for treating aquatic mycosis.

Description

Technical Field

[0001] This invention relates to a novel ochratoxin, and more particularly to an ochratoxin-like compound extracted from secondary metabolites of marine fungi that has activity against aquatic pathogens, as well as its preparation method and uses. Background Technology

[0002] Aquaculture, a core link in the global food supply chain, has an annual output exceeding 120 million tons (FAO 2025). However, diseases caused by pathogens result in annual losses of up to $9 billion for the industry. Current disease control faces a triple challenge: first, the pathogen spectrum is becoming increasingly complex, with dominant strains such as Vibrio and Aeromonas evolving multi-type drug resistance; second, the overuse of traditional antibiotics has spawned superbugs carrying resistance genes such as NDM-1; and third, existing disinfectants (such as potassium persulfate) have ecotoxicological residues. Taking shrimp farming as an example, an outbreak of acute hepatopancreatic necrosis disease (AHPND) can wipe out an entire farm within 72 hours, and Edwardsiella tarda, which forms biofilms, can even penetrate polyethylene net cages. More seriously, the horizontal transfer of drug-resistant genes in nearshore aquaculture areas has affected the gene pool of wild populations, creating a complex ecological and economic crisis. Against this backdrop, developing marine-derived antimicrobial agents with novel targets has become a strategic choice to overcome the bottlenecks in the sustainable development of aquaculture.

[0003] The overuse of traditional antibiotics (such as florfenicol and oxytetracycline) has led to frequent outbreaks of drug-resistant strains, necessitating the development of novel antibacterial agents. Marine fungi, as a natural treasure trove of marine secondary metabolites, exhibit unique ecological adaptability in their antibacterial mechanisms, showing great application potential, particularly in the development of drugs against aquatic pathogens. During a chemical investigation of the ethyl acetate extract of the marine fungus *Aspergillus* sp. fermented in culture medium, the inventors discovered a novel ochratoxin. Currently, there are no reports on the chemical structure and anti-aquatic pathogen activity of this compound, and therefore, no related drugs are available on the market. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an ochratoxin with activity against aquatic pathogens, its preparation method and uses.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] 1. An ochratoxin-like compound with activity against aquatic pathogens, the structural formula of which is shown in (I):

[0007]

[0008] 2. The preparation method of the above-mentioned ochratoxin-like compounds with anti-aquatic pathogenic bacteria activity includes the following steps:

[0009] (1) Fermentation production

[0010] Aspergillus ustus with accession number CCTCC NO: M2014086 was inoculated into PDB liquid medium and cultured on a shaker at 25-32℃ for 5-9 days. Seed liquid free from microbial contamination was screened out and inoculated into sterilized rice medium. It was then statically cultured in a constant temperature incubator at 25-32℃ for 20-40 days to obtain the fermentation product.

[0011] (2) Extraction of extract

[0012] Ethyl acetate was added to the fermentation product obtained in step (1), and the extraction was repeated 3 to 4 times. The ethyl acetate extract was then evaporated by rotary evaporation to obtain a crude extract.

[0013] (3) Isolation, purification and preparation of compounds

[0014] First, the crude extract obtained in step (2) was fully dissolved in a mixture of dichloromethane and methanol in a volume ratio of 1:1. Then, 200-300 mesh silica gel was added and the mixture was stirred. Normal-phase medium-pressure column chromatography was performed, using a mixture of petroleum ether and ethyl acetate in a volume ratio of 3:7 as the eluent. The eluent was collected and mixed with 100-200 mesh reversed-phase silica gel. Then, reversed-phase medium-pressure column chromatography was performed, using a methanol-water eluent with a methanol volume percentage of 20-100% for linear gradient elution for 120 min. The eluted fractions were collected and arranged in descending order of polarity, and combined to obtain 5 components. The second component was purified by semi-preparative reversed-phase high-performance liquid chromatography using a mixture of acetonitrile and water in a volume ratio of 40:60 as the mobile phase to obtain compound I, the structure of which is shown in (I).

[0015]

[0016] Furthermore, the preparation method of the PDB liquid culture medium in step (1) is as follows: Take 200g of peeled and diced potatoes, add 1000mL of distilled water and boil for 10-60min, filter and retain the filtrate, add 20g of glucose to the filtrate, stir until completely dissolved, adjust the volume to 1000mL with distilled water, autoclave at 121℃ for 15-20mL and cool, and it can be used for culture.

[0017] Furthermore, the rice culture medium prepared in step (1) is prepared as follows: Take 100g of rice, add 110mL of distilled water and 3g of sea salt, put the mixture into a culture bottle, and then sterilize it by high pressure steam at 121℃ for 20min and then cool it for inoculation and fermentation.

[0018] Furthermore, the flow rate of the mobile phase in the semi-preparative reversed-phase high-performance liquid chromatography described in step (3) is 2 mL / min.

[0019] The present invention also provides the use of the above-mentioned ochratoxin compounds in the preparation of drugs against aquatic pathogens.

[0020] The present invention also provides the use of the above-mentioned ochratoxin compounds in the preparation of drugs against Edwardsiella tarda.

[0021] The present invention also provides the use of the above-mentioned ochratoxin compounds in the preparation of drugs that inhibit LPS-induced macrophage inflammation.

[0022] Compared with the prior art, the advantages of the present invention are as follows: The present invention discloses an ochratoxin-like compound with anti-aquatic pathogenic bacteria activity, its preparation method and uses. The fermentation product is obtained by microbial fermentation culture, and then the fermentation product is extracted by soaking in ethyl acetate to obtain a crude extract. The crude extract is then purified by medium-pressure normal-phase column chromatography, medium-pressure reverse-phase column chromatography and semi-preparative high-performance liquid chromatography. The compound has significant anti-aquatic pathogenic bacteria activity and can be used in the development of drugs to inhibit related diseases caused by aquatic pathogenic bacteria.

[0023] The aforementioned Aspergillus ustus strain DJ003, with accession number CCTCC NO: M2014086, was deposited on March 14, 2014, at the China Center for Type Culture Collection, Wuhan University, Wuhan, China. Attached Figure Description

[0024] Figure 1 High-resolution mass spectrometry (HR-ES1-MS) of the compounds of this invention;

[0025] Figure 2 The ultraviolet (UV) spectrum of the compound of this invention is shown below.

[0026] Figure 3 The proton nuclear magnetic resonance spectrum of the compound of this invention (NMR) 1 HNMR);

[0027] Figure 4 The carbon NMR spectrum of the compound of this invention ( 13 C NMR);

[0028] Figure 5The DEPT-135 NMR spectrum of the compound of this invention;

[0029] Figure 6 The COSY NMR spectrum of the compound of this invention;

[0030] Figure 7 The HSQC nuclear magnetic resonance spectrum of the compound of this invention;

[0031] Figure 8 The nuclear magnetic resonance HMBC spectrum of the compound of this invention;

[0032] Figure 9 The key to the compound of this invention 1 H- 1 Correlation between H COSY (thick blue line) and HMBC (red arrow);

[0033] Figure 10 Experimental and calculated values ​​of the ECD spectra of the compounds of this invention;

[0034] Figure 11 This is a single-crystal diffraction pattern (X-ray) of the compound of the present invention;

[0035] Figure 12 The results represent the cytotoxicity of the compounds to normal cells, where A represents LX-2 cells, B represents HEK293T cells, and C represents Raw264.7 cells.

[0036] Figure 13 The compound inhibits LPS-induced inflammatory response in macrophages in a dose-dependent manner, where A represents NO production and BD represents the effects of the compound on the expression of IL-1β (B), IL-6 (C), and TNF-α (D) mRNA.

[0037] Figure 14 The figures show the direct and indirect antibacterial effects of the compounds against Edwardsiella tarda. A represents the effect of different concentrations of the compound on the growth curve of Edwardsiella tarda; BC represents the effect of the compound on the phagocytic ability of macrophages against Edwardsiella tarda; DG represents the effect of the compound on the phagocytic ability of macrophages against FITC-labeled microspheres; H represents the standard curve of Edwardsiella tarda copy number versus RT-qPCR Ct value; I represents the effect of RT-qPCR on Edwardsiella tarda viability and plate counting method on the bactericidal activity of the compound on Raw264.7 cells. In the figures, * indicates P < 0.05, ** indicates P < 0.001, *** indicates P < 0.0001, and **** indicates P < 0.00001. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0039] Example 1: The structural formula of an ochratoxin-like compound derived from marine fungi with activity against aquatic pathogens is shown in (I):

[0040]

[0041] Example 2, the preparation method of the ochratoxin-like compounds shown in Example 1, the specific steps are as follows:

[0042] (1) Fermentation production

[0043] Aspergillus ustus with accession number CCTCC NO: M2014086 was inoculated into PDB liquid medium and cultured on a shaker at 120 rpm and 28°C for 7 days. Seed liquid free from microbial contamination was screened out and inoculated into sterilized rice medium according to standard operating procedures. It was statically cultured in a constant temperature incubator at 28°C for 30 days to obtain fermentation products.

[0044] (2) Extraction of extract

[0045] Ethyl acetate was added to the fermentation product obtained in step (1), and the extraction was repeated 3 to 4 times. The ethyl acetate extract was evaporated by rotary evaporation to obtain 33g of crude extract.

[0046] (3) Isolation, purification and preparation of compounds

[0047] First, the crude extract obtained in step (2) was fully dissolved in a mixture of dichloromethane and methanol in a volume ratio of 1:1. Then, 200-300 mesh silica gel was added and the mixture was stirred. Normal-phase medium-pressure column chromatography was performed, using a mixture of petroleum ether and ethyl acetate in a volume ratio of 3:7 as the eluent. The eluent was collected and mixed with 100-200 mesh reversed-phase silica gel. Then, reversed-phase medium-pressure column chromatography was performed, using a methanol-water eluent with a methanol volume percentage of 20-100% for linear gradient elution for 120 min. The eluted fractions were collected and arranged in descending order of polarity, and combined to obtain 5 components. The second component was purified by semi-preparative reversed-phase high-performance liquid chromatography using a mixture of acetonitrile and water in a volume ratio of 40:60 as the mobile phase to obtain compound I, the structure of which is shown in (I).

[0048]

[0049] Example 3: Structural identification of ochratoxin compounds.

[0050] The ochratoxin compound prepared in Example 2 above is a brown crystal, and compound 1 is a light brown crystal, as shown above. Figure 1 and Figure 2As shown, its molecular formula was determined by HR-ESI-MS (m / z 400.1395 [M+H]). + The calculated value (400.1395) is determined to be C. 21 H 21 NO7 indicates the presence of 12 degrees of unsaturation. For example... Figure 3 As shown, 1 The H NMR spectrum showed two sets of characteristic aromatic proton signals: δ H 7.1-7.2 (5H, overlap, H-14-18) and δ H 6.94 (1H, s, H-6) / 8.06 (1H, s, H-7) correspond to a monosubstituted benzene ring (L-Phe structural unit) and a tetrasubstituted benzene ring (4-hydroxymellein structural unit), respectively. Figure 4 and Figure 5 As shown, 13 C10 NMR and DEPT spectral analysis revealed 18 carbon signals, including 8 quaternary carbons, 11 methines, 1 methylene, and 2 methyl carbons. For example... Figure 6 , Figure 7 and Figure 8 As shown, the key HMBC-related signal is: H3-21(δ H 1.63) and H-6 (δ) H 6.94) and C-5 (δ) C 66.9) related, H-5(δ) H 4.55) and C-2(δ C 107.7) related, H-6 and C-2 / C-8 (δ C 120.0) related, H-7(δ) H 8.06) and C-1(δ C 144.6) / C-9(δ C The 4-hydroxymelin skeleton structure was confirmed by correlation with 160.2) and combined with COSY correlation signals (H-4 / H-21; H-6 / H-7). The L-phenylalanine unit was confirmed by the following evidence: Figure 9 As shown, H2-12(δ H 3.20) and C-19 (δ) C 171.9) related, H-14 / H-18 and C-12 (δ C 38.0) related, H-11(δ) H 5.01) and C-13(δ C Evidence for the connection between L-Phe and 4-hydroxymelin via an amide bond (C-10-N) and the COSY correlation signal of H-11 / H2-12, as well as the HMBC correlation signal of H-6 and C-10 (δC 169.8), is derived from the HMBC correlation signal of H-6 and C-10 (δC 169.8). Figure 10 and Figure 11 As shown, the absolute configuration was finally determined to be 4R,5R,11S by matching analysis of experimental ECD (MeOH) and time-dependent DFT calculations (PBE1PBE / def2-TZVP / PCM) and combined with single-crystal X-ray diffraction data.

[0051] Table 1. NMR data of compound 1 ( 1 H, 600; 13 C, 150MHz; CDCl3)

[0052]

[0053]

[0054] Note 1: s—single peak, d—double peak, q—quartet, m—multiple peak, overlapped—overlapped, br s—broad single peak.

[0055] Note 2: 1 H was obtained by 600MHz NMR; 13 C was obtained by 150MHz NMR.

[0056] Example 4: Anti-aquatic pathogenic bacteria activity of ochratoxin compounds prepared by the method of Example 2.

[0057] 1. Experimental Method:

[0058] (1) The cells were arranged at an appropriate density (8 × 10⁶ cells per well). 3 Up to 1×10 4 Cells were seeded into 96-well plates and incubated overnight at 37°C in a 5% CO2 cell culture incubator. Three replicates were performed for each sample. Different final concentrations (1 μM, 5 μM, 10 μM, 25 μM, 50 μM) of the compound were added to each well, and the plates were incubated for 24 hours. 10 μL of CCK-8 reagent was added to each well containing 100 μL of culture medium. The plates were then incubated at 37°C in a humidified environment with 5% CO2 for 1–4 hours in the dark. The absorbance (OD) at 450 nm was measured using a microplate reader. Relative cell viability is expressed as a percentage relative to the control group, which was considered to have 100% viable cells.

[0059] (2) Screening of compounds using an LPS-induced macrophage inflammation model. RAW264.7 macrophages were plated and cultured in a 5% CO2 cell culture incubator at 37°C for 24 h. The cells were simultaneously treated with the compound (final concentration 10 μM) and LPS (100 ng / mL) for 24 h. The supernatant culture medium was collected to detect NO content, and RNA was extracted from the cells to detect the expression of inflammatory factors IL-6, IL-1β, TNF-α, and mRNA.

[0060] (3) The effects of different doses of the compound on NO and inflammatory factor expression in LPS-induced macrophage inflammation were tested. RAW264.7 macrophages were plated and cultured in a 5% CO2 cell culture incubator at 37°C for 24 h. The compound (final concentrations of 5 μM and 10 μM) and LPS (100 ng / mL) were treated simultaneously for 24 h. The supernatant culture medium was collected to detect NO content, and RNA was extracted from the cells to detect the expression of inflammatory factors IL-6, IL-1β, TNF-α, and mRNA.

[0061] (4) Take Edwardsiella tarda from the -80℃ freezer, inoculate it into TSB medium, and incubate overnight on a shaker at 28℃. After counting the bacteria in the overnight culture, dilute the solution 1000 times and add 200 μL (1×10⁻⁶) to each well of a 96-well plate. 8 CFU / mL bacterial culture was added. Compounds were added to final concentrations of 12.5 μM, 25 μM, and 50 μM. The negative control group received only 100 μL of culture medium. The positive control (ciprofloxacin, Cip.) was added at a final concentration of 0.5 μg / mL. Each treatment was performed in triplicate.

[0062] (5) Edwardsiella tarda phagocytosis assay. RAW264.7 macrophages were seeded and, after cell adhesion, treated with compounds (final concentrations of 5 μM and 10 μM) and positive control drugs for 24 hours, with a control group included. Edwardsiella tarda in logarithmic growth phase was treated with BacLight. TM Red bacterial staining was performed. RAW264.7 macrophages were infected at a 10:1 infection ratio and incubated for 2 hours. After incubation, the supernatant was discarded, and the cells were gently washed twice with 1 ml of PBS buffer. After discarding the supernatant, 4℃ PBS buffer was added again. The adherent macrophages were scraped off the cell wall with a cell scraper, and the cell suspension was collected for flow cytometry analysis.

[0063] (6) FITC-labeled microsphere phagocytosis assay. RAW264.7 macrophages were seeded and, after cell adhesion, treated with compounds (final concentrations of 5 μM and 10 μM) and positive control drugs for 24 h, with a control group included. Cells were co-incubated with fluorescent microspheres for 2 h. After incubation, the supernatant was discarded, and the cells were gently washed twice with 1 mL of PBS buffer. After discarding the supernatant, 4℃ PBS buffer was added again, and the adhered macrophages were scraped off the microspheres. The cell suspension was collected and analyzed by flow cytometry.

[0064] (7) Sterilization. RAW264.7 cells were treated with the compound as described previously and then infected with live *E. tarda* bacteria at a fold-in-infection (MOI) ratio of 10 for 30 minutes. After infection, cells were incubated with 80 μg / mL gentamicin for 15 minutes to eliminate extracellular bacteria and allow for the degradation of RNA from dead extracellular bacteria. Macrophages were then washed three times with sterile PBS. Two experimental groups were established: an "uptake" group, in which samples were collected immediately after gentamicin treatment for RNA extraction; and a "kill" group, in which cells were further incubated for 1.5 hours to allow for the elimination of intracellular bacteria before lysis. For real-time quantitative polymerase chain reaction (RT-qPCR) analysis, RNA was extracted from both groups and reverse transcribed into cDNA. The 16S rRNA gene of *E. tarda* was amplified using specific primers. Ct values ​​were analyzed using a standard curve to determine the CFU / mL value in each sample. Simultaneously, cell lysates extracted from both groups were serially diluted and inoculated onto TCBS agar. The bacteria were incubated at 28°C for 24 hours, and then colonies were counted to calculate CFU. Bacterial survival was calculated by normalizing the CFU counts of the kill group to the CFU counts of the ingestion group.

[0065] 2. Experimental Results: The compounds of this invention exhibit the following anti-aquatic pathogenic bacteria activity: Figure 12 , 13 As shown in Figure 14.

[0066] (1) The compound showed no cytotoxic effects on normal cells. The effects of the compound on the human hepatocyte line LX-2 were investigated using CCK8 assay. Figure 12 A) Kidney cell line HEK293T ( Figure 12 B) and mouse macrophages Raw 264.7 ( Figure 12 C) Cytotoxicity. The results showed that the compound had no cytotoxicity to Raw 264.7, LX-2 and HEK293T cells even after 72 hours of incubation at concentrations below 100 μM.

[0067] (2) The compound can inhibit LPS-induced macrophage inflammatory response: The effects of the compound on NO and cytokine levels were further evaluated using an LPS-induced macrophage model, such as... Figure 13A, Figure 13 B and Figure 13 Results showed that the compound could inhibit LPS-induced NO production and reduce IL-6 and TNFα levels, exhibiting superior anti-inflammatory activity compared to the positive control dexamethasone (DEX) at high concentrations. Furthermore, as... Figure 13 As shown in Figure C, the compound also inhibits LPS-induced upregulation of IL-1β expression. Further studies have shown that the anti-inflammatory effect of this compound is concentration-dependent.

[0068] (3) The compound promotes the clearance of Edwardsiella pneumoniae by enhancing macrophage-mediated bactericidal activity rather than direct antibacterial effects.

[0069] Edwardsiella tarda is a Gram-negative bacterium known to infect a variety of hosts, including fish, amphibians, and mammals, posing a significant threat to agriculture, food, and human health. Given the significant immunomodulatory properties of the compound, we further investigated its potential antibacterial activity against Edwardsiella tarda. The effect of compound 1 on bacterial proliferation was assessed using a microbroth dilution method combined with dynamic growth monitoring via ELISA. The results showed that the compound had no direct antibacterial activity against Edwardsiella tarda. Figure 14 A).

[0070] A key virulence characteristic of Edwardsiella tarda is its ability to survive and replicate within host cells, particularly phagocytes, a process mediated by various virulence factors that support immune evasion and successful infection. Therefore, we evaluated the effects of a compound on macrophage phagocytosis and bactericidal function. The study found that the compound significantly enhanced macrophage inhibition of Edwardsiella tarda (… Figure 14 B and 14C) and FITC-labeled microspheres ( Figure 14 Phagocytosis of D and 14E. Notably, compound treatment reduced the proportion of cells phagocytosing individual microspheres (D and 14E). Figure 14 F), while increasing the percentage of cells that engulf two or more microspheres ( Figure 14 G). More importantly, compared with the untreated group, the compound significantly enhanced the bacterial clearance capacity of macrophages in a dose-dependent manner (G). Figure 14 H and 14I).

[0071] The foregoing description is not intended to limit the invention, nor is the invention limited to the examples given. Any changes, modifications, additions, or substitutions made by those skilled in the art within the scope of the invention should also be considered within the protection scope of the invention.

Claims

1. An ochratoxin-like compound with activity against aquatic pathogens, characterized in that... The compound is an ochratoxin derived from marine fungi, and its structural formula is shown in (1).

2. The method for preparing an ochratoxin-like compound with anti-aquatic pathogenic bacteria activity as described in claim 1, characterized in that... Includes the following steps: (1) Fermentation production Aspergillus ustus with accession number CCTCC NO: M2014086 was inoculated into PDB liquid medium and cultured on a shaker at 25-32℃ for 5-9 days. Seed liquid free from microbial contamination was screened out and inoculated into sterilized rice medium. It was then statically cultured in a constant temperature incubator at 25-32℃ for 20-40 days to obtain the fermentation product. (2) Extraction of extract Ethyl acetate was added to the fermentation product obtained in step (1), and the extraction was repeated 3 to 4 times. The ethyl acetate extract was then evaporated by rotary evaporation to obtain a crude extract. (3) Isolation, purification and preparation of compounds First, the crude extract obtained in step (2) was fully dissolved in a mixture of dichloromethane and methanol in a volume ratio of 1:

1. Then, 200-300 mesh silica gel was added and the mixture was stirred. Normal-phase medium-pressure column chromatography was performed, using a mixture of petroleum ether and ethyl acetate in a volume ratio of 3:7 as the eluent. The eluent was collected and mixed with 100-200 mesh reversed-phase silica gel. Then, reversed-phase medium-pressure column chromatography was performed, using a methanol-water eluent with a methanol volume percentage of 20-100% for linear gradient elution for 120 min. The eluted fractions were collected and arranged in descending order of polarity, and combined to obtain 5 components. The second component was purified by semi-preparative reversed-phase high-performance liquid chromatography using a mixture of acetonitrile and water in a volume ratio of 40:60 as the mobile phase to obtain compound I, the structure of which is shown in (I).

3. The method for preparing an ochratoxin-like compound with anti-aquatic pathogenic bacteria activity according to claim 2, characterized in that... The preparation method of PDB liquid culture medium in step (1) is as follows: Take 200g of peeled and diced potatoes, add 1000mL of distilled water and boil for 20-40 minutes. Filter and retain the filtrate. Add 20g of glucose to the filtrate and stir until completely dissolved. Adjust the volume to 1000mL with distilled water. Autoclave at 121℃ for 15-20mL and then cool. It is ready for culture.

4. The method for preparing an ochratoxin-like compound with anti-aquatic pathogenic bacteria activity according to claim 2, characterized in that... The rice culture medium prepared in step (1) is as follows: Take 100g of rice, add 110mL of distilled water and 3g of sea salt, put the mixture into a culture bottle, and then autoclave it at 121℃ for 20min. After cooling, it can be used for inoculation and fermentation.

5. The method for preparing an ochratoxin-like compound with anti-aquatic pathogenic bacteria activity according to claim 2, characterized in that: The flow rate of the mobile phase in the semi-preparative reversed-phase high-performance liquid chromatography described in step (3) is 2 mL / min.

6. Use of the ochratoxin compound of claim 1 in the preparation of a drug for treating aquatic pathogens.

7. Use of the ochratoxin compound of claim 6 in the preparation of an anti-Edwardsiella tarda drug.

8. Use of the ochratoxin compound of claim 1 in the preparation of a drug for inhibiting LPS-induced macrophage inflammation.

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