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A new benzophenone with biological activities purified from Aspergillus fumigatus SWZ01 Bing Liu , Ning Chen , Ying-xiang Chen , Jie-jing Shen , Ying Xu & Yu-bin Ji To cite this article: Bing Liu , Ning Chen , Ying-xiang Chen , Jie-jing Shen , Ying Xu & Yu-bin Ji (2020): A new benzophenone with biological activities purified from Aspergillus�fumigatus SWZ01, Natural Product Research, DOI: 10.1080/14786419.2020.1825427 To link to this article: https://doi.org/10.1080/14786419.2020.1825427

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NATURAL PRODUCT RESEARCH https://doi.org/10.1080/14786419.2020.1825427

A new benzophenone with biological activities purified from Aspergillus fumigatus SWZ01 Bing Liua,b,c, Ning Chenb,d, Ying-xiang Chena,d, Jie-jing Shend, Ying Xub,d and Yu-bin Jia,d a Pharmaceutical Engineering Technology Research Center, Harbin University of Commerce, Harbin, China; bPostdoctoral Center of Chinese Pharmacy, Harbin University of Commerce, Harbin, China; c Postdoctoral workstation, Institute of Pharmacology, Harbin University of Commerce, Harbin, China; d National Center for Anti-cancer Natural Medicine Engineering, Harbin, China

ABSTRACT

ARTICLE HISTORY

Strain SZW01 was isolated from sea sediment collected from Shenzhen in Guangdong province, China, and was later identified as Aspergillus fumigatus by16S rDNA sequence analysis. Various chromatographic processes led to the isolation and purification of three compounds from the fermentation culture of SZW01, including a new compound, 2,6’-dihydroxy-2,4’dimethoxy-8’methyl-6-methoxy-acyl-ethyl-diphenylmethanone (1), and two known compounds: fumigaclavine C (2) and alternarosin A (3), as characterised by UV, IR, 1 D, 2 D-NMR and MS data. The antioxidant and a-glucosidase inhibitory activities of these compounds were evaluated. The result illustrated that compound 1 exhibited a moderate antioxidant activity and stronger a-glucosidase inhibitory activity than acarbose.

Received 2 July 2020 Accepted 1 September 2020 KEYWORDS

Benzophenone; antioxidant activity; a-glucosidase inhibitory activity

CONTACT Bing Liu [email protected] Supplemental data for this article can be accessed online at https://doi.org/10.1080/14786419.2020.1825427. ß 2020 Informa UK Limited, trading as Taylor & Francis Group

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1. Introduction Aspergillus fumigatus is one of the most common species in the genus aspergillus (Sun et al. 2004). A. fumigatus has a wide range of sources, such as medicinal plants, plant symbionts and animal organs. Some metabolic components produced by A. fumigatus can cause serious damage to the body, leading to the formation and spread of invasive aspergillosis, which seriously endangers life and health. Studies have represented that its metabolites have certain potential to develop into active drug. So far, several compounds have been isolated from the metabolites of A. fumigatus. However, due to the high toxicity, general pharmacological activity and small amount of products, it is difficult to get good development (Zhu and Liu 1998). In recent years, it has been found that some of these compounds have new pharmacological activities (Hamayun et al. 2009, Li et al. 2018), such as antibacterial activity (Li et al. 2018), antitumor activity (Han et al. 2007), etc, especially in anti-tumor aspects. They can not only be used to study the mechanism of tumor occurrence, development, invasion and metastasis, but also to obtain new anti-tumor drugs through structural modification to reduce side effects. Natural benzophenone is a kind of compounds with special structure in iridaceae, garciniaceae, lauraceae, moraceae, rosaceae, daphneceae, myrtle family and other plants. It is generally believed that natural benzophenone is the intermediate of xanthone in organism, which is composed of two benzene rings connected by a carbonyl group, and contains 13 main substituents which are hydroxyl, methoxy, glycosyl, isopentenyl. These natural compounds have a variety of biological activities, such as antiallergy, inhibition of a-glucosidase, anti-inflammatory and cardiovascular protection. They have the advantages of low effective dose and little side effects. Some benzophenone derivatives isolated from Garcinia plants have anti HIV activity (Rubio et al. 2005). Additionally, studies have shown that the modified natural benzophenone has more significant anti-inflammatory, antitumor and antibacterial activities. It is believed that with the further study of the relationship between bioactivity and structure activity of natural benzophenones, it will promote the discovery and development of new drugs.

2. Results and discussion 2.1. Taxonomy of the strain SZW01 The strain SZW01 16S rDNA gene was submitted in the GenBank Database with the accession number GU566228.1.

2.2. Structure determination Compound 1 was obtained as a yellow powder. HRESIMS established its molecular formula as C19H20O7 at m/z 361.1105 [M þ H]þ. The 1H NMR (400 MHz, DMSO) spectrum revealed one phenolic proton signal at dH 12.9 (1H, s). The signals at dH 6.89 (1H, d, J ¼ 1.8 Hz), 6.69 (1H, d, J ¼ 1.8 Hz), 6.38 (1H, s) and 6.25 (1H, s) were assignable to two groups of meta-coupled aromatic protons.

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Figure 1. Chemical structures of 1, 2 and 3.

In addition, proton signals at dH 3.61 (3H, s), 3.61 (3H, s), 3.33 (3H, s), 2.25(3H, s) and 3.20(2H, s) confirmed the existence of four methyl groups and one methylene group. The 13C NMR (150 MHz, DMSO) spectrum of 1 gave 19 carbons, including two carbonyls signal at dC 199.4, 166.0, twelve benzene carbons signals at dC 163.3, 160.8, 158.9, 156.7, 147.7, 128.1, 125.3, 110.2, 110.1, 107.4, 103.5 and 103.3, three methoxyl signals at dC 55.9, 55.9, 52.1, one methylene signal at dC 40.6, and one methyl signal at dC 21.9. The NMR data suggested that compound 1 and 2,20 ,4,40 -tetrahyoxy-80 -methyl-6methoxy-acyl-ethyl-diphenylmethanone reported in the literature (Liu et al. 2015) share the same molecular skeleton (Figure 1). All proton signals were assigned to their directly attached carbons by HSQC spectral data. The structures of rings A and B in compound 1 were determined by the multiplicities and correlations exhibited in the HMBC spectrum. The HMBC correlations from 6.38 (H-50 ) to 21.9 (C-80 ), 103.3 (C-30 ); 6.25 (H-30 ) to 21.9 (C-80 ), 110.2 (C-30 ); 3.61 (90 OCH3) to 156.7 (C-20 ); 2.25 (H-80 ) to 147.7 (C-40 ), 110.2 (C-50 ), 103.3 (C-30 ) led to the elucidation of ring A. The other group of HMBC correlations from 6.89 (H-5) to 103.5 (C3), 158.9 (C-4), 166.0 (C-8), 40.6 (C-7); 6.69 (H-3) to 125.3 (C-1), 110.1 (C-5), 158.9 (C-4) confirmed the structure of ring B. Thus far, the only position that was vacant for substituent in compound 1 was C-6, and there were only one methenyl group and one carbonyl methyl ester group that were not assigned. Finally, the fragment 2a was elucidated and considered to be located at C-6 of ring B by the HMBC correlations from 3.20 (H-7) to 125.3 (C-1), 128.1 (C-6), 110.1 (C-5), 166.0 (C-8) and from 3.61 (9-OCH3) to 166.0 (C-8) and 3.33 (10-OCH3) to 158.9 (C-4). In the NOSEY spectrum, 3.17 (H-7) is related to 6.89 (H-5), showed that the side chain of ethyl methanoate is linked to the C-6. On the basis of these results, the structure of compound 1 was determined to be 2,60 -dihydroxy-2,4’dimethoxy-80 -methyl-6-methoxyacyl-ethyl-diphenylmethanone. Compound 2 and 3 were isolated as white amorphous powder. It was identified as fumigaclavine C (Shen et al. 2015) and alternarosin A (Wang et al. 2009) (Figure 1).

2.3. Antioxidant activities of compounds 1, 2 and 3 In recent years, some scholars have reported that benzophenone compounds have significant antioxidant activity (Tzvetomira et al. 2009; Eva Muriithi et al. 2016). The antioxidant activity of the compound the metabolites 1, 2 and 3 were evaluated by

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DPPH and ABTSþ radical scavenging method (Table 1). The compound 1 showed significant free radical scavenging ability. In the DPPH free radical scavenging experiment, compound 1 showed a relatively weak free radical scavenging capacity compared to the positive control Vc (IC50¼25.13 lM) with an IC50 value of 28.62 lM. In the ABTSþ radical scavenging experiment, 1 showed stronger than the positive control Vc (IC50¼12.5 lM).

2.4 a-Glucosidase inhibitory activities of compounds 1, 2 and 3 The compounds 1–3 were tested for a-glucosidase inhibitory activity, and the test method refers to the test method of butyrolactone compounds in the literature (Dewi. et al. 2014; Gu, et al. 2019). Acarbose is a clinically common a-glucosidase inhibitor derived from secondary metabolites of microorganisms (Kim et al). The results (Table 2) showed that compound 1 exhibited stronger a-glucosidase inhibitory activity than acarbose, compounds 2 and 3 displayed relatively weak inhibitory activities when comparing with acarbose.

2.5. Molecular docking of compound 1 2.5.1. Molecular docking of compound 1 with human antioxidant protein Prx5 The antioxidant protein superfamily Peroxiredoxin is widely present in prokaryotes and eukaryotes, including 6 members Prx1, 2, 3, 4, 5, 6 (Wood et al. 2003). Antioxidant protein family Peroxiredoxin proteins have a conserved cysteine residue at the N-terminus, and some proteins have a conserved cysteine residue at the C-terminus. In this paper, the human antioxidant protein Prx5 was selected as the research object, and its crystal structure (PDB ID: 4k7o) was taken from the Protein Crystal Bank to explore the molecular docking of compound 1. The AutoDock molecular docking program was used to simulate the docking of compound 1 with Prx5 to study the binding conformation of them. The docking score is 7.9. The docking results show that compound 1 binds to Prx5 after the small molecule ligand enters the active pocket of the receptor, the 2-OH, 60 -OH and 9-OCH3, 10OCH3 are respectively associated with the amino acid residues Asp114, Gly92, and Val70, Arg95 of Prx5 by hydrogen bonding. 60 -OH has ionic bridge with the amino acid residue Lys63 of Prx5. 2.5.2. Molecular docking of compound 1 with a-glucosidase After a meal, the alpha glucosidase present on the brush border of the small intestinal mucosa will hydrolyze the carbohydrates in the food to glucose, and glucose is absorbed into the blood circulation to raise blood sugar. Therefore, alpha glucosidase is the main control of postprandial blood glucose One of the target enzymes (Zheng et al. 2013). In this paper, a-glucosidase was selected as the research object, and its crystal structure (PDB ID: 3a4a) was taken from the Protein Crystal Bank to explore its molecular docking with compound 1. The AutoDock molecular docking program was used to simulate the docking of compound 1 with a-glucosidase to study the binding conformation of them. The

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docking score is 8.6. The docking results show that compound 1 binds to a-glucosidase after the small molecule ligand enters the active pocket of the receptor. The 2OH and the carbonyl group at the C-8 are, respectively, associated with the amino acid residues Tyr158 and Asp307 of a-glucosidase by hydrogen bonding. The 9-OCH3 has a polar interaction with the amino acid residue His280 of a-glucosidase. The actual test biological activity is basically consistent with the docking score law, indicating that using a-glucosidase as a virtual screening receptor, the established molecular docking model is reliable and has good predictive ability. Polyhydroxybenzophenone has a diphenyl and polyhydroxy structure similar to flavonoids and resveratrol, and has good antioxidant and anti-diabetic activities (Wu et al. 2010). Compound 1 is able to enter the active pocket of the receptor protein. The phenolic hydroxyl, carbonyl and 6-methoxy-acyl-ethyl in its structure can have a good binding effect with the key amino acid residues on Human antioxidant protein Prx5 and a-glucosidase. It is the structural basis for its good antioxidant activity and anti-diabetic activity. Benzophenone is the main metabolite of A. fumigatus, which also makes A. fumigatus one of the medicinal microorganisms that researchers pay close attention to. In the future, A. fumigatus can metabolize benzophenone compounds in large quantities by regulating the gene of A. fumigatus and chemical epigenetic modification, laying the foundation for future research.

3. Experimental 3.1. General experimental procedures The NMR spectral data were recorded on Bruker AV-600 (400 MHz for 1H and 150 MHz for 13C) with tetramethylsilane (TMS) as the internal standard (Bruker Co.). The HR-ESIMS data were obtained on the Micromass AutoSpec-UltimaE TOF mass spectrophotometer (Bruker Co.). Chromatography was carried out on silica gel (200–300 mesh; Qingdao Haiyang Chemical Factory, Qingdao, China), Sephadex LH-20 (Pharmacia, Piscataway, NJ, USA) and reversed-phase HPLC (Waters 2684, USA).

3.2. Fungi material The fungus was isolated from sediment collected at Shenzhen in Guangdong province, China. The strain SZW01 was isolated after incubation at 28 for 1 week on modified potato dextrose agar (PDA) with artificial sea water instead of NaCl and distilled water. The genomic DNA of strain was prepared. PCR amplification of 16S rDNA and sequencing was performed with conventional methods. The 16S rDNA sequences were performed using BLASTN. The 16S rDNA sequences were aligned with published sequences from the GeneBank database (http://www.ncbi.nlm.nih.gov) using the NCBI BLASTN comparison software. The closest relatives of the remaining sequences were obtained from the GeneBank database using BLAST program; sequence similarity was 100% between strain SZW01 and A. fumigatus.

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3.3. Fermentation, extraction and isolation SZW01 into 500 mL baffled flasks containing 200 mL of the broth (mannitol 2%, glucose 2%, yeast extract 0.5%, peptone 1%, KH2PO4 0.05%, MgSO47H2O 0.03%, corn steep liquor 0.1%, sea salt 3.3% in deionised water, pH 7.0) was fermented by shake culturing at 28  C for 7 days, a total of about 3 L of fermented seed liquid was obtained. Solid rice was fermented in 30 bottles (500 mL bottles), each containing 80 g rice and 110 mL water, and autocluded for 20 minutes at 121  C. The rice culture medium was taken out and lowered to room temperature, and each bottle was poured into 100 mL fermented seed liquid, and stood for 40 days at room temperature. Fermented mycelium methanol ultrasonic for 3 times, combined with extraction solution, decompression and solvent removal to obtain 500 g extract. The 500 g extract is dispersed in water, and extracted with dichloromethane to obtain 108 g extract. The dichloromethane crude extract (108.0 g) was subjected to silica gel column and eluted with CH2Cl2-CH3OH (100:0-0:1), yielding 15 fractions (F1–F15). Fraction 3 (8 g) was purified by silica gel column and eluted with (petroleum ether-acetone (100:0-0:1)), yielding 4 fractions(F3.1–F3.4). Fraction 3.4 (800 mg) was purified by Sephadex LH-20 column chromatography (Pharmacia, Piscataway, NJ, USA) (CH3OH) and semi-preparative HPLC (CH3OH-H2O 63:37, flow rate 3 mL/min, wavelength 210 nm) to obtain compound 1 (28.5 mg, retention time 32.4 min). Fraction 5 (1.3 g) was purified by Sephadex LH-20 column chromatography (Pharmacia, Piscataway, NJ, USA) (CH3OH) and semi-preparative HPLC (CH3OH-H2O 40:60, flow rate 3 mL/min, wavelength 210 nm) to obtain compound 2(18.0 mg, retention time 17.4 min) (Shen et al. 2015) and 3(8.2 mg, retention time 36.6 min) (Wang et al. 2009).

3.3.1. Compound 1 Compound 1: yellow powder; HRESI-MS m/z 361.1105 [M þ H]þ (calcd for C19H20O7, 361.1105). 1H NMR(400 MHz, DMSO-d6) dH：2.25(3H, s, H-80 ), 3.20(2H, s, H-7), 3.33(3H, s, H-10), 3.61(6H, s, H-9, 90 ), 6.25(1H, s, H-30 ), 6.38(1H, s, H-50 ), 6.69(1H, d, J ¼ 1.8 Hz, H3), 6.89(1H, d, J ¼ 1.8 Hz, H-5), 12.9(1H, br s, 60 -OH).13C NMR(150 MHz, DMSO-d6) dC： 21.9(C-80 ), 40.6(C-7), 52.1(C-9), 55.9(C-10, 90 ), 103.3(C-30 ), 103.5(C-3), 107.4(C-10 ), 110.1(C5), 110.2(C-50 ), 125.3(C-1), 128.1(C-6), 147.7(C-40 ), 156.7(C-20 ), 158.9(C-4), 160.8(C-2), 163.3(C-60 ), 166.0(C-8), 199.4(C-70 ). 3.3.2. Compound 2 Compound 2: white amorphous powder; HRESI-MS m/z 366.5123 [M þ H]þ (calcd for C23H30N2O2, 366.5169). 1H NMR(600 MHz, DMSO-d6)dH： 1.23(3H, d, J ¼ 7.3, CH3-14), 1.47(6H, s, H-18-CH3), 1.48(6H, s, H-17-CH3), 2.52(3H, s, H-CH3CO), 2.51(2H, m, H-9)、 3.20(1H, s, H-10), 3.43(1H, dd, J ¼ 13.8, 3.6 Hz, H-16), 5.01(1H, d, J ¼ 17.4 Hz, H-21), 5.50(1H, t, J ¼ 2.7, H-15), 6.13(1H, dd, J ¼ 17.4, 10.8 Hz, H-20), 6.50(1H, d, J ¼ 7.8 Hz, H7), 6.92(1H, t, J ¼ 7.8 Hz, H-6), 7.06(1H, d, J ¼ 7.8 Hz, H-5). 13C NMR(150 MHz, DMSO-d6) dC： 16.4(C-14), 27.3(C-18), 27.4(C 17), 28.7(C-9), 32.6(C-13), 39.4(C-19), 39.5(C-16), 42.8(C-11), 57.0(C-12), 61.4(C-10), 70.7(C-15), 104.5(C-2), 108.1(C-7), 111.3(C-21), 111.4(C5), 121.1(C-6), 127.3(C-3), 128.3(C-4), 132.6(C-1), 137.2(C-8), 146.2(C-20), 169.9(CO).

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3.3.3. Compound 3 Compound 3: white amorphous powder; HRESI-MS m/z 492.5610 [M þ H]þ (calcd for C22H24N2O7S2, 492.1013). 1H NMR(400 MHz, DMSO-d6)dH： 1.98(3H, s, 9-O COCH3), 2.19(3H, s, 2-SCH3), 2.20(3H, s, 20 -SCH3), 2.95(1H, d, J ¼ 15.2 Hz, H-3), 3.25(1H, br d, J ¼ 15.2 Hz, H-3), 4.39(1H, tt, J ¼ 7.6, 2.0 Hz, H-90 ), 4.72(1H, dd, J ¼ 8.0, 2.0 Hz, H-8), 4.75(1H, br d, J ¼ 7.6 Hz, H-10), 4.81(1H, dd, J ¼ 8.0, 2.0 Hz, H-80 ), 4.95(1H, br d, J ¼ 8.0 Hz, H-100 ), 5.28(1H, br d, J ¼ 7.6 Hz, 90 -OH), 5.61(1H, dt, J ¼ 8.0, 2.0 Hz, H-9), 6.29(1H, dd, J ¼ 8.4, 2.4 Hz, H-70 ), 6.45(1H, dd, J ¼ 8.4, 2.4 Hz, H-7), 6.67(1H, br s, H-50 ), 6.77(1H, br s, H-5). 13C NMR(150 MHz, DMSO-d6) dC： 14.3(20 -SCH3), 14.4(2-SCH3), 20.9(9-CH3 COCH3), 38.9(C-30 ), 39.2(C-3), 59.9(C-10), 63.4(C-100 ), 70.2(C-20 ), 71.3(C-9, 90 ), 71.4(C-2), 105.7(C-8), 110.7(C-80 ), 111.3(C-4), 111.5(C-40 ), 136.5(C-50 ), 137.4(C-5), 138.2(C70 ), 140.3(C-7), 164.3(C-10 ), 164.7(C-1), 169.8(9-CO COCH3). 3.4. Antioxidant assay 3.4.1. Dpph method Weigh accurately DPPH 3.94 mg, dissolve it in absolute ethanol, dilute it to a 10 ml brown volumetric flask, dilute it 5 times, prepare a solution with a concentration of 0.2 mM, measure its absorbance at 517 nm, and set the absorbance value 0.7 or so. The concentration of L-ascorbic acid and the test compound is 10,050,251,051 lg/ml with absolute ethanol. Pipette 100 lL into a 96-well plate with a pipette, and then add 100 lL of different concentrations of the sample solution (10,050,251,051 lg/ml) dissolved in ethanol, respectively. After mixing, the mixture was allowed to stand at room temperature for 30 min, and the absorbance of each well was measured by a microplate reader at 517 nm; the activity of each compound to scavenge DPPH radicals was calculated by the following formula:   DPPH scavenging activity ð%Þ ¼ 1  ðSsample  SBblank Þ=ðCcontrol  CBblank Þ  100% Among them, the sample blank SB： sample solution 100 lL þ absolute ethanol 100 lL； Sample S：sample solution 100 lL þ DPPH 100 lL； Negative control C：absolute ethanol 100 lL þ DPPH 100 lL； Blank control CB：absolute ethanol 200 lL.

3.4.2. Abts method Preparation of 0.01 mol/L PBS: 0.395 g NaCl, 0.1 g KCl, 0.12 g KH2PO4 and 0.9 g K2HPO4 was dissolved in 400 ml of distilled water. Then adjusted the solution to pH 7.4 with HCl, finally adjusted to 500 ml, placed in a refrigerator, and refrigerated. Preparation of potassium persulfate (2.45 mmol/L): 0.0066 g of potassium persulfate was diluted to 10 ml with distilled water. Preparation of ABTS solution: 0.0384 g of ABTS was diluted to 10 ml with PBS. ABTSþ free radical generation: Mix the above prepared potassium persulfate solution and ABTS solution in a volume ratio of 1:1, and leave it at room temperature for 12  16 hours to generate ABTSþ. This solution was diluted with PBS (0.01 M) having

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a pH of 7.4, and when it had an absorbance at 734 nm of 0.70 (± 0.02), the absorbance was measured after equilibration at 30  C for 30 min. The concentration of L-ascorbic acid and the test compound is 100,502,510,521 lg/ ml with absolute ethanol. Place the ABTSþ(150 lL) solution in a 96-well plate, add 100 lL of different concentrations of the sample solution (100,502,510,521 lg/ml), mix well and protect from light. After standing for 20 min, the absorbance of each hole was measured at 734 nm with a microplate reader.; The ABTSþ free radical scavenging activity of this compound was calculated as follows:   ABTS þ  scavenging activity ð%Þ ¼ 1  ðSsample  SBblank Þ=ðCcontrol  CBblank Þ  100% Among them, the sample blank SB：sample solution 100 lL þ PBS 150 lL； Sample S：sample solution 100 lL þ ABTSþ 150 lL； Negative control C：absolute ethanol 100 lL þ PBS 150 lL； Blank control CB：absolute ethanol 100 lL þ ABTSþ 150 lL.

3.5 a-Glucosidase inhibitory activity assay 25 lL of a-glucosidase (0.070 U/mL; EC 3.2.1.20, Type I, yeast source, Sigma, Shanghai, China), 49.5 lL of 0.1 M phosphate buffer solution (pH 7.0), 0.5 lL of different concentrations The sample solution was pre-incubated in a 96-well plate at 37  C for 5 minutes; then 25 lL of 3 mM p-nitrophenyl-a-D-glucopyranoside (pNPG, Sigma, Shanghai, China) was added to start the reaction; after incubation at 37  C for 15 minutes, Add 100 lL of Na2CO3 (0.2 M) to stop the reaction. Acarbose (Belavin, Beijing, China) and anhydrous quercetin (purity > 95%, derived from rutin hydrolysate) were used as positive controls. The inhibitory effect is determined by measuring the amount of pNPG at k 410 nm using a microplate reader (Model 680, Thermo Fisher, Fermont, CA, USA).

3.6. Molecular docking assay The three-dimensional structure files of a-glucosidase (PDB ID：3a4a) and Human antioxidant protein Prx5 (PDB ID： 4k7o) crystals are all derived from the RCSB protein database (http://www.rcsb.org/pdb/home) as the receptor model for computer molecular docking. Use Notepad software to remove small molecules including ACR, GOL, HOH, NAG, and SO4 as a template for molecular docking.Use ChemBioDraw to draw the planar framework of compound 1, build a two-dimensional structure database, and convert to Chem3D module to obtain the three-dimensional structure diagram of small molecules and the pdb format file of each small molecule. Confirm the hydrogenation, charge, and protonation status of the small molecule pdb format, and finally save ligand.pdb as the ligand structure for molecular docking. Run AutoDock to open the ligand.pdb and construct the ligand.pdbqt file, which contains the atom information and the rotatable bond information in the ligand structure. Set the size of the docking box through GridBox, and save the gpf file after saving the settings. Run

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Docking-Lamrckian GA, select the Lamarck genetic algorithm as the docking algorithm, and save it as the protein_ligand.dpf file, which contains the information of molecular docking. The default number of docking conformations is 10, and the number of docking conformations is manually modified to 20 (Ga_run20). Run the AutoGrid and AutoDock programs. Run the AutoGrid4 program to get the information of all the atoms in the docking; run the AutoDock program to dock, the docking result file is saved in the dlg file, and the docking score is obtained.

4. Conclusion In this paper, a new compound 2,60 -dihydroxy-2,4’dimethoxy-80 -methyl-6-methoxyacyl-ethyl-diphenylmethanone and two known compounds(fumigaclavine C and alternarosin A)were isolated from the fermentation culture of A. fumigatus SZW01. Compound 1 exhibited a moderate antioxidant activity and stronger a-glucosidase inhibitory activity than acarbose. Compound 1 is expected to become a lead compound in anti-diabetes.

Disclosure statement No potential conflict of interest was reported by the authors.

Funding This work was supported by Postdoctoral support plan of Harbin University of Commerce [grant No. 2017BSH003], University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province [grant No. UNPYSCT-2018140], Harbin University of Commerce “Young Innovative Talents” Support Program [grant No. 2019CX38], Harbin University of Commerce Doctoral Research Startup Fund [grant No. 2019DS111], Harbin University of Commerce “Young Innovative Talents” Support Program [grant No. 2019CX09].

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