CN117298088A

CN117298088A - Application of cis-6-octadecenoic acid in preparation of antifungal drugs

Info

Publication number: CN117298088A
Application number: CN202311407086.5A
Authority: CN
Inventors: 王彦; 王欣荣; 仲华; 张俊平; 赵庆杰
Original assignee: Second Military Medical University SMMU
Current assignee: Second Military Medical University SMMU
Priority date: 2023-10-27
Filing date: 2023-10-27
Publication date: 2023-12-29

Abstract

The invention discloses an application of cis-6-octadecenoic acid or medicinal salt thereof in preparing antifungal medicines, wherein the structure of the cis-6-octadecenoic acid is shown as follows:the invention utilizes candida albicans monoallel gene knockout bacteria library to screen out fructose-1, 6-bisphosphate aldolase as an antifungal action target of PeAc, wherein the PeAc is an inhibitor of fructose-1, 6-bisphosphate aldolase. According to the invention, the PeAc is found to exhibit better in-vitro antifungal activity by widely screening a natural compound library by using a trace liquid-based dilution method. According to the invention, the PeAc is found to show good in-vivo antifungal activity by a mouse and wax moth larva fungus infection experiment. According to the invention, through researches of a chessboard type trace liquid-based dilution method, a bacteriostasis circle method and a growth curve method, the combination of PeAc and fluconazole shows definite synergic drug-resistant fungus resisting effect.

Description

Application of cis-6-octadecenoic acid in preparation of antifungal drugs

Technical Field

The invention belongs to the technical field of medicinal chemistry, and particularly relates to application of cis-6-octadecenoic acid in preparation of antifungal medicines.

Background

In recent years, with the increasing number of immunocompromised individuals such as cancer patients, organ transplant recipients, elderly patients, etc., the incidence and mortality of invasive fungal infections (Invasive Fungal Infections, IFIs) has increased. Invasive Candida infections (Invasive Candidiasis, IC) predominate in IFIs, with mortality rates roughly estimated to be higher than 40%, which in turn are based on Candida albicans (Candida albicans) as the dominant infectious strain. Candida albicans can cause superficial and deep fungal infections of human bodies in a yeast state and a hypha state, and can be adhered to the inner dirty surface or the surface of biological materials by forming a biological film with compact structure, so that the candida albicans is difficult to remove, and repeated infections are caused. The antifungal drugs commonly used clinically at present comprise azoles, polyenes, echinocandins, allylamines and the like, and with the annual use of the traditional drugs, the phenomenon of fungus resistance is increased clinically, which also becomes one of the main reasons of fungus infection treatment failure. In addition, the traditional antifungal medicines have the problems of more or less large toxicity, low effective rate, high price and the like, and are difficult to meet the requirements of human health, so that development of novel antifungal medicines with high efficiency and low toxicity is urgently needed.

Cis-6-octadecenoic acid (Petroselinic Acid, hereinafter, peAc is used for cis-6-octadecenoic acid) is unsaturated fatty acid in coriander, carrot, etc., and has the structural formula shown in (I), and the moleculeC (C) ₁₈ H ₃₄ O ₂ Molecular weight 282.46.

Studies have shown that: peAc regulates the intestinal bacterial flora (genes.2022; 13 (11): 1967.). PeAc is a bactericide of Porphyromonas gingivalis, and is a main active ingredient of plant extracts for preventing and treating periodontal diseases (Microbiol.2022; 13:816047.). PeAc inhibits the formation of biofilms of staphylococcus aureus, including methicillin-resistant staphylococcus aureus, and also inhibits the production of staphylococcus aureus virulence factors (Microbiology spot.2022; 10 (3) e 0133022). PeAc can reduce intestinal damage and apoptosis in mice with intestinal ischemia/reperfusion injury (British journal of anaesthesia.2022;128 (3): 501-12.). The fungus kingdom (eumyces) is a kingdom of organisms, is a large class of higher eukaryotes, is completely different from bacteria, and most of the reports are research reports of PeAc against pathogenic bacteria, but the research of PeAc against pathogenic fungi related to the invention has not been reported at home and abroad at present.

Haploid deficiency effect analysis (haploinsufficiency profiling, HIP) is one of the effective methods of finding antifungal drug targets. The literature reports that diploid fungi have halved gene dosage (gene dose) after deleting an allele encoding a drug target, and the sensitivity of the drug target gene deletion fungus to drugs is greatly increased, which is called a haploid deficiency effect. Researchers can use haploid deficiency effect to screen gene knockout bacteria sensitive to drugs by constructing a gene knockout bacteria library, thereby identifying drug targets. In 2014 Science has reported the identification of the fluconazole drug target Erg11p and tamoxifen drug target Neo1p using the Saccharomyces cerevisiae gene knockout bacteria library (science.2014; 344 (6180): 208-11). Scientists also used the haploid deficiency effect to make sure that the antifungal drug target of turbomicin was Sec14p (science.2020; 370 (6519): 974-8), the antifungal drug target of F901318 was dihydrolactate dehydrogenase (DHODH) (Proc Natl Acad Sci U S A.2016;113 (45): 12809-14), the antifungal drug targets of compounds G884, G365 were Gwt1p (ACS effect Dis.2015;1 (1): 59-72), and the like.

Disclosure of Invention

The invention aims to provide an application of cis-6-octadecenoic acid in preparing antifungal medicines.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

the first aspect of the invention provides an application of cis-6-octadecenoic acid or pharmaceutically acceptable salts thereof in preparing antifungal medicines.

The structure of the cis-6-octadecenoic acid (Petroselinic Acid, peAc) is shown below:

the antifungal action target of the cis-6-octadecenoic acid is Fructose-1,6-bisphosphate aldolase (Fructose-1, 6-bisphosphate aldolase, fba1 p). Cis-6-octadecenoic acid exerts an antifungal effect by fructose-1,6-bisphosphate aldolase (Fba 1 p).

The pharmaceutically acceptable salts refer to acid addition salts of cis-6-octadecenoic acid with the following acids: hydrochloric acid, sulfuric acid, nitric acid, citric acid, maleic acid, and the like.

The fungus is selected from candida albicans, candida krusei, candida tropicalis, trichophyton mentagrophytes and the like; the method specifically comprises the following steps: candida albicans (Candida albicans) SC5314; candida krusei (Candida krusei) 4996, 62588, 10153; trichophyton mentagrophytes (Trichophyton mentagrophytes) T5b, T5a; candida tropicalis (Candida tropicalis) 409, 8915; candida albicans 14103, 7654, 9161, 10066, 10060, 10061, 7879, 901, 953.

The effective concentration of the cis-6-octadecenoic acid or the medicinal salt thereof in the candida albicans resisting medicine is more than or equal to 2 mug/ml; the effective concentration of the cis-6-octadecenoic acid or the medicinal salt thereof in the anti-candida krusei medicament is more than or equal to 2 mug/ml; the effective concentration of the cis-6-octadecenoic acid or the medicinal salt thereof in the candida tropicalis medicament is more than or equal to 32 mug/ml; the effective concentration of the cis-6-octadecenoic acid or the medicinal salt thereof in the trichophyton mentagrophytes resisting medicine is more than or equal to 4 mug/ml.

The second aspect of the invention provides an application of cis-6-octadecenoic acid or medicinal salt thereof in preparing antifungal medicines in cooperation with clinically common antifungal medicines.

The clinical common antifungal medicine is selected from clinical common antifungal medicines such as fluconazole, ketoconazole, itraconazole, amphotericin B, caspofungin, terbinafine and the like.

The invention discovers that for fluconazole resistant candida albicans, the combined use of PeAc and fluconazole can reduce the effective concentration of the medicament, so that the effective concentration of fluconazole is reduced from 64 mug/ml to 0.5 mug/ml. The preferred combination regimen is a PeAc concentration of 2 μg/ml+fluconazole concentration of 0.5 μg/ml; or PeAc concentration of 2 μg/ml+fluconazole concentration of 1 μg/ml.

The invention discovers that the PeAc has very low toxicity at the antifungal effective concentration, and can generate toxicity to mammalian cells when the concentration is more than or equal to 64 mug/ml.

In a third aspect, the invention provides the use of cis-6-octadecenoic acid or a pharmaceutically acceptable salt thereof for the manufacture of a Fructose-1,6-bisphosphate aldolase inhibitor (Fructose-1, 6-bisphosphate aldolase, fba1 p).

Experiments prove that the PeAc plays an antifungal role through Fba1p, and the PeAc is an inhibitor of Fructose-1,6-bisphosphate aldolase (Fructose-1, 6-bisphosphate aldolase, fba1 p). The method specifically comprises the following steps: the scientific and feasible application of the haploid deficiency effect to drug target identification is proved by constructing a candida albicans monoallel knockout bacteria library, the drug target of PeAc antifungal is researched according to the haploid deficiency effect, fructose-1,6-bisphosphate aldolase is the drug target of PeAc, and PeAc is a fructose-1,6-bisphosphate aldolase inhibitor.

In the invention, when the wax moth larvae (example 7) or the mice (example 7) are used as an in-vivo experimental model of fungal infection, the survival rate of the wax moth larvae infected by the fungi can be obviously improved when the PeAc concentration reaches 32mg/kg, and the survival rate of the mice infected by the fungi can be obviously improved when 16 mg/kg.

By adopting the technical scheme, the invention has the following advantages and beneficial effects:

the present invention has found an effective antifungal compound with a proprietary potential: cis-6-octadecenoic acid (PeAc). The compound PeAc in the invention has definite antibacterial effect on pathogenic fungi such as Candida albicans (Candida albicans), candida krusei (Candida krusei), candida tropicalis (Candida tropicalis), trichophyton mentagrophytes (Trichophyton mentagrophytes) and the like, and MIC ₈₀ Between 2-32 mug/ml. PeAc can inhibit the growth of Candida albicans, inhibit the formation of Candida albicans hyphae (2 μg/ml) and biofilm (16 μg/ml). The PeAc also shows better antifungal activity on fluconazole resistant strains in candida albicans and candida krusei (natural resistance to fluconazole), and the PeAc and fluconazole show synergistic antifungal effect when combined. The PeAc has low cytotoxicity and can effectively improve the survival rate of the larva and the mice infected by the fungus. The invention also discovers that the fructose-1,6-bisphosphate aldolase inhibitor is a drug target of PeAc, which is the fructose-1,6-bisphosphate aldolase inhibitor.

The invention provides the use of cis-6-octadecenoic acid (Petroselinic Acid, peAc) as an antifungal compound and the use of cis-6-octadecenoic acid as a fructose-1,6-bisphosphate aldolase inhibitor. The in-vitro and in-vivo experiments prove that the PeAc has wide antifungal spectrum, can obviously inhibit the formation of candida albicans hyphae, and also has better antifungal activity on fluconazole resistant bacteria; the combination of the PeAc and the fluconazole shows definite synergic action of resisting the drug-resistant fungi; peAc can increase the survival rate of animals infected by fungi, and has low toxicity to mammalian cells. PeAc is an antifungal compound with pharmaceutical potential. According to researches such as haploid deficiency effect analysis, the invention discovers that Fructose-1,6-bisphosphate aldolase (Fructose-1, 6-bisphosphate aldolase, fba1 p) is a drug target of PeAc, and experiments prove that the PeAc plays an antifungal role through the Fba1p, and cis-6-octadecenoic acid is a Fructose-1,6-bisphosphate aldolase inhibitor.

According to the invention, the candida albicans single allele knock-out bacteria library is utilized to screen out an antifungal action target point of which Fba1p is PeAc, wherein the PeAc is an inhibitor of the Fba1 p. According to the invention, the PeAc is found to exhibit good antifungal activity by widely screening a natural compound library by using a trace liquid-based dilution method.

Drawings

FIG. 1 is a schematic diagram showing the results of inhibiting the formation of hyphae of Candida albicans SC5314 by PeAc from a concentration of 2. Mu.g/ml in example 2.

FIG. 2 is a graph showing the results of inhibition of biofilm formation by Candida albicans SC5314 by PeAc at a concentration of 16. Mu.g/ml in example 3.

Fig. 3 is a schematic diagram of the results of measuring the zone of inhibition of drug-resistant fungi by PeAc in combination with fluconazole in example 5.

FIG. 4 is a graph showing the quantitative relationship between PeAc and fluconazole in example 6.

FIG. 5 is a graph showing the results of PeAc in example 7 effective in increasing survival rate of Candida albicans infected mice.

FIG. 6 is a graphical representation of the cytotoxicity results of PeAc in example 8.

FIG. 7 is a schematic of the strategy for creating a pool of single allele knock-outs of Candida albicans in example 9.

FIG. 8 is a schematic representation of the implementation of the establishment of a pool of single allele knock-outs of Candida albicans in example 9.

FIG. 9 is a schematic representation of the implementation of the establishment of a pool of single allele knock-outs of Candida albicans in example 9.

Figure 10 is a schematic of the results of a spot-plating experiment in a feasibility validation of the haploid deficiency effect in example 10 for identification of an antifungal drug target.

FIG. 11 is a schematic diagram of the results of MIC experiments in the feasibility of the haploid deficiency effect of example 10 for identification of targets of antifungal agents.

FIG. 12 is a schematic of the results of a spot-plating experiment in a proprietary verification of the use of the haploid deficiency effect in the identification of antifungal drug targets in example 10.

FIG. 13 is a schematic representation of the results of MIC experiments in which the haploid deficiency effect of example 10 was used in the specific validation of antifungal drug target identification.

FIG. 14 is a schematic representation of the results of spot plate experiments and MIC experiments for application of the haploid deficiency effect to PeAc target screening in example 10.

FIG. 15 is a schematic diagram of the results of the spot-plate and MIC experiments of example 10 using the haploid deficiency effect for PeAc target screening

FIG. 16 is a schematic representation of the results of examining the mode of action of PeAc and Fba1p by molecular docking in example 10.

FIG. 17 is a schematic diagram showing the results of verification of the inhibition of hypha formation by PEAc exerting antifungal effect through Fba1p in example 11.

FIG. 18 is a schematic diagram showing the results of inhibition of biofilm formation by PeAc exerting antifungal effect through Fba1p in example 11.

FIG. 19 is a schematic representation of the results of the survival experiments of wax moth larvae in example 11 where PeAc exerts antifungal effect through Fba1p.

Detailed Description

In order to more clearly illustrate the present invention, the present invention will be further described with reference to preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and that this invention is not limited to the details given herein.

The invention discovers that the compound PeAc has better antifungal activity and synergistic antifungal activity with fluconazole, the cytotoxicity of the PeAc is low, and the antifungal action target point of the PeAc is Fba1p.

In the present invention, the fungi used may be obtained or cultured by a conventional method, or may be obtained by a commercially available route such as isolation from somatic cells or tissues of a patient suffering from the corresponding disease, or purchased from any of the commercial institutions or companies of standard strains such as ATCC. It should be understood that the strain samples used in the examples of the present invention are merely illustrative examples, and any fungus that can form hyphae or biofilm or is resistant to fluconazole can be used to test the antifungal activity of the compounds of the present invention without limiting the scope of the examples. It should be understood that in the examples of the present invention, only the minimum concentration of the active ingredient is indicated as being effective in inhibiting fungal hyphae formation, biofilm formation. It is known in the art that the antifungal effect is improved to some extent when the concentration of the antifungal active pharmaceutical ingredient is increased. Thus, dosages above the minimum concentration may be employed to inhibit fungal hyphae formation or biofilm growth by any person skilled in the art, after reading this specification, by combining with common general knowledge in the art, and such variations are within the scope of the present disclosure.

Example 1: determination of PeAc antifungal Spectrum

Materials and methods

1. Reagent: peAc: purchased from Shanghai Tao Shu Biotech Co. Fluconazole (FLC): purchased from Shanghai Ala Biochemical technologies Co., ltd. Dimethyl sulfoxide (DMSO): purchased from Macklin corporation. The PeAc and fluconazole are prepared into 10mg/ml solution by DMSO, and the tested medicine is preserved at the temperature of minus 20 ℃. Before the experiment, the medicine storage liquid is taken out and put into a 35 ℃ incubator to be melted, and the medicine storage liquid is fully and uniformly mixed to respectively carry out the subsequent experiment.

2. Strains: ATCC standard strain: candida albicans (Candida albicans) SC5314 (commercially available from ATCC). The remaining strains; candida krusei (Candida krusei) 4996, 62588, 10153, trichophyton mentagrophytes (Trichophyton mentagrophytes) T5b, T5a, candida tropicalis (Candida tropicalis) 409, 8915 are offered by the dermatology of the Shanghai long-sign hospital; candida albicans 14103, 7654, 9161, 10066, 10060, 10061, 7879, 901, 953 are provided by the medical system pharmaceutical chemistry teaching and research laboratory of the navy university.

All candida strains for experiments are subjected to scratch activation on a sandcastle glucose agar medium (SDA), are cultured for 48 hours at 35 ℃, then are respectively picked up and subjected to scratch activation again, the monoclonal obtained in the second time is placed on an SDA inclined plane, and are cultured by the method and then are stored at 4 ℃ for standby. Trichophyton mentagrophytes are activated in potato dextrose agar (PDA medium) as described above.

3. Culture solution: RPMI 1640 medium: RPMI 1640 (Gibco BRL) 10g, naHCO ₃ 2.0 34.5g (0.165M) of morpholinopropane sulfonic acid (morpholinepropanesulfonic acid, MOPS) (Sigma) are dissolved in 900ml of distilled water, the pH is adjusted to 7.0 (25 ℃) by 1NNaOH, the volume is fixed to 1000ml, filtered and sterilized, and the mixture is stored at 4 ℃.

Sandcastle dextrose agar medium (SDA): 10g of peptone, 40g of glucose and 18g of agar, adding 900ml of triple distilled water for dissolution, adding 50ml of 2mg/ml chloramphenicol water solution, adjusting the pH to 7.0, fixing the volume to 1000ml, and preserving at 4 ℃ after high-pressure sterilization.

YPD liquid medium: 10g of yeast extract, 20g of peptone and 20g of glucose, adding 900ml of triple distilled water for dissolution, fixing the volume to 1000ml, and preserving at 4 ℃ after autoclaving.

4. Instrument: constant temperature incubator (Shanghai-constant scientific instruments Co., ltd. -MJ-150-I); shaking incubator (Jiangsu Taicang laboratory equipment Co., ltd. HZ-2111K-B); multifunctional enzyme labeling instrument (TECAN Infinite M200).

5. Preparing a drug sensitive plate: candida albicans was inoculated in YPD liquid medium and cultured at 30℃for 16 hours. The activated bacterial liquid is sucked into a 1.5ml centrifuge tube, centrifuged for 1min at 3000g, the culture medium is sucked and removed, the PBS is used for washing once, the supernatant is centrifuged and removed, the supernatant is resuspended in 1ml PBS, and 10 μl is taken to be counted by a blood cell counting plate after dilution. Adjusting the concentration of the bacterial liquid to 1X 10 by using RPMI 1640 culture medium ³ cells/ml. Transferring the bacterial liquid into a disposable reagent tank, uniformly mixing by blowing with a plurality of liquid movers for a plurality of times, then sucking 100 mu l of the bacterial liquid to 3 rd-12 th columns of a prepared 96-well plate, adding 200 mu l of the bacterial liquid in the 2 nd column, and adding 100 mu l of RPMI 1640 liquid culture medium in the first column as a blank control. The mother liquor was prepared from PeAc and FLC with DMSO. PeAc, FLC were added to each well of the second column to a final concentration of 64. Mu.g/ml (note that the DMSO content in each well was less than 1%), and 3 wells were made for each drug. Multichannel pipettor for 2-11 holes2-fold dilution was performed. No. 12 wells were not dosed as growth controls. Culturing the prepared drug sensitive plate in a 35 ℃ incubator. After 24h/48h, the drug sensitive plate is mixed by shaking, and OD value of each hole is measured at 630nm by using an enzyme-labeled instrument. The concentration of the drug in the lowest concentration well with the OD value reduced by more than 80% is MIC compared with the growth control well ₈₀ (drug concentration at which fungal growth was 80% inhibited) and the experimental results are shown in Table 1.

Conclusion: the results in Table 1 show that PeAc has stronger antibacterial effect on common pathogenic fungi and has wider antibacterial spectrum. PeAc showed stable antimicrobial activity against all 10 strains of Candida albicans tested, MIC ₈₀ Between 2-16 μg/ml, the fluconazole resistant strain in candida albicans in particular shows similar antifungal activity as the sensitive strain. Has better antifungal activity to 3 candida krusei (natural drug resistance to fluconazole) and MIC ₈₀ 2. Mu.g/ml. The antibacterial activity on trichophyton mentagrophytes is kept between 4-8 mug/ml, and the trichophyton mentagrophytes also has a certain antibacterial effect on 2 strains of candida tropicalis, MIC ₈₀ 32. Mu.g/ml.

TABLE 1

Example 2: determination of the inhibition of candida albicans hyphae formation by PeAc

Materials and methods

1. Reagent: peAc: purchased from Shanghai Tao Shu Biotech Co. Dimethyl sulfoxide (DMSO): purchased from Macklin corporation. PeAc was prepared as a 10mg/ml solution in DMSO and the test drug was stored at-20deg.C. Before the experiment, the medicine storage liquid is taken out and put into a 35 ℃ incubator to be melted, and the medicine storage liquid is fully and uniformly mixed for the subsequent experiment.

2. Strains: ATCC standard strain: candida albicans (Candida albicans) SC5314 (commercially available from ATCC). The candida albicans strain is subjected to scratch activation in a sandcastle glucose agar medium (SDA), cultured for 48 hours at 35 ℃, then the monoclonal is respectively selected and subjected to scratch activation again, the monoclonal obtained in the second time is placed on an SDA inclined plane, and the culture is carried out by the method and then the culture is preserved at 4 ℃ for standby.

3. Culture solution

Spider liquid medium: weighing 10g of Nutrient broth, 10g of mannitol and K ₂ HPO ₄ 2.0 g, adding double distilled water for dissolution, fixing the volume to 1L in a measuring cylinder, sterilizing at high temperature and high pressure, and storing in a refrigerator at 4 ℃.

Lee liquid medium: precisely weighing 0.5g of alanine, 1.3g of leucine, 1.0g of lysine, 0.1g of methionine, 0.0714g of ornithine, 0.5g of phenylalanine, 0.5g of proline and 0.5g of threonine, and respectively adding (NH) after ultrasonic dissolution in a proper amount of triple distilled water ₄ ) ₂ SO ₄ 0.5 g，MgSO ₄ ·7H ₂ O 0.357g，K ₂ HPO ₄ 0.25 5.0g of NaCl, 0.001g of biotin and 12.5g of glucose are fully stirred and dissolved, water is continuously added to fix the volume to 1L, the sterilization is carried out at high temperature and high pressure, and the mixture is placed in a refrigerator at 4 ℃ for storage.

4. Instrument: constant temperature incubator (Shanghai-constant scientific instruments Co., ltd. -MJ-150-I); shaking incubator (Jiangsu Taicang laboratory equipment Co., ltd. HZ-2111K-B); philips XL-30 inverted phase contrast microscope (Amersham Pharmacia AMG EVOS X1).

5. Preparation and observation of liquid hyphae

Candida albicans was inoculated in YPD liquid medium and cultured at 30℃for 16 hours. The activated bacterial liquid is sucked into a 1.5ml centrifuge tube, centrifuged for 1min at 3000g, the culture medium is sucked and removed, the PBS is used for washing once, the supernatant is centrifuged and removed, the supernatant is resuspended in 1ml PBS, and 10 μl is taken to be counted by a blood cell counting plate after dilution. Adjusting bacteria concentration to 2×10 with Spider liquid culture medium and Lee liquid culture medium respectively ⁵ cells/ml, bacterial liquid was taken in 12-well plates, 2 ml/well. A series of concentrations (0, 2, 4, 8. Mu.g/ml) of the drug to be tested was then added to each well, and the mixture was left to stand at 37℃for 3 hours, and the formation of hyphae was observed and photographed with an inverted microscope. The experimental results are shown in FIG. 1, FIG. 1 is The results of PeAc in example 2 in inhibiting the formation of hyphae of Candida albicans SC5314 from a concentration of 2. Mu.g/ml are schematically shown.

The results show that PeAc has a clear effect of inhibiting liquid hyphae formation. Under the condition of no drug action, candida albicans forms slender and non-segmented true hyphae in two hyphae induction culture mediums. In the Spider liquid medium, 2 mug/ml of PeAc can obviously inhibit the formation of candida albicans hyphae, 4 mug/ml of candida albicans stays in a yeast state mostly, and the inhibition of candida albicans hyphae formation is dose-dependent. In the Lee liquid medium, candida albicans hyphae also begin to shorten under the action of 2 mug/ml of PeAc, the hyphae become shorter gradually along with the increase of the concentration of the PeAc, and the hyphae become shorter obviously when the concentration of the PeAc is 8 mug/ml.

Example 3: determination of the inhibition of candida albicans biofilm by PeAc

Materials and methods

1. Reagent: peAc: purchased from Shanghai Tao Shu Biotech Co. XTT (sodium 2,3-Bis- (2-methoxy-4-nitro-5-sulfophenyl) -2H-tetrazolium-5-carboxanide, 3' - [1- [ (anilino) -carbonyl ] -3, 4-tetrazole ] -Bis (4-methoxy-6-nitro) benzene-sulfonate): purchased from Macklin corporation. Menadione (menadione): purchased from Macklin corporation. Dimethyl sulfoxide (DMSO): purchased from Macklin corporation. Acetone: purchased from Sigma. PeAc was prepared as a 10mg/ml solution in DMSO and the test drug was stored at-20deg.C. Before the experiment, the medicine storage liquid is taken out and put into a 35 ℃ incubator to be melted, and the medicine storage liquid is fully and uniformly mixed for the subsequent experiment.

Dissolving menadione with acetone to prepare stock solution with concentration of 10m M, and storing in dark place; the XTT powder was weighed and dissolved in PBS to prepare a 0.5mg/ml solution, which was mixed well in a ratio of 1. Mu.l menaquinone stock solution per 10ml XTT solution and sterilized by filtration through a 0.22 μm microporous filter, the whole procedure being kept from light. XTT, menaquinone were stored at-80 ℃. Before the experiment, the medicine storage liquid is taken out and put into a refrigerator with the temperature of 4 ℃ and a temperature box with the temperature of 35 ℃ to be melted in a gradient way, and the medicine storage liquid is fully and uniformly mixed for pharmacodynamics experiment.

2. Strains: ATCC standard strain: candida albicans (Candida albicans) SC5314 (commercially available from ATCC). All experimental strains are subjected to streak activation on a sandcastle glucose agar medium (SDA), candida albicans is cultured for 48 hours at 35 ℃, then monoclonal is selected and subjected to streak activation again, the monoclonal obtained in the second time is placed on an SDA inclined plane, and the culture is carried out by the method and then the culture is preserved at 4 ℃ for standby.

3. Culture solution

5. Preparation of candida albicans biological envelope

Candida albicans is inoculated in YPD liquid culture medium and cultured at 30 ℃ for 16 hours, so that fungi are in the late stage of exponential growth phase. The activated bacterial liquid is sucked into a 1.5ml centrifuge tube, centrifuged for 1min at 3000g, the culture medium is sucked and removed, the PBS is used for washing once, the supernatant is centrifuged and removed, the supernatant is resuspended in 1ml PBS, and 10 μl is taken to be counted by a blood cell counting plate after dilution. Adjusting the bacterial concentration to 1×10 with Spider liquid culture medium ⁶ cells/ml. The bacterial solution was added to the surface-treated 96-well plate (tissue culture treated, TC-treated) in an amount of 100. Mu.l per well. Note that column 1 was left empty and Spider broth was added as a blank. The 96-well plate is placed in a constant temperature incubator at 37 ℃ for 90min, so that candida albicans cells are settled and adhered on the surface of the well.

6. Preparation of candida albicans-resistant biological envelope drug-sensitive plate

A new 96-well plate is taken, 150 μl of Spider liquid culture medium is added into each well, 150 μl of culture medium (total 300 μl) is additionally added into column 1, 1.92 μl of PeAc (final concentration is 64 μg/ml) is added, 150 μl is sucked into corresponding well of column 2 after being blown and mixed uniformly by a multi-channel pipette, and then blown and mixed uniformly again, the line-ratio dilution is carried out according to the types (final concentrations are 32, 16, 8, 4, 2, 1, 0.5, 0.25 and 0.125 μg/ml in sequence), and no drug is added into column 12, and only DMSO with corresponding volume is added. After the dosing plate is manufactured, the biological film plate adhered with the biological film plate for 90min is taken out, the upper culture medium is sucked, PBS is used for gently washing for 2-3 times, the adhered cells are prevented from being washed off as much as possible, then the liquid medicine in the dosing plate is sequentially added into the corresponding hole sites in the biological film plate, 100 mu l of the liquid medicine is added into each hole, and the culture plate is continuously placed in a constant temperature incubator at 37 ℃ for culturing for 24h.

7. Determination of biofilm Activity

The 96-well plate incubated for 24h was removed, the medium was aspirated, washed gently three times with PBS, then 150. Mu.l of XTT reaction (well No. 12) was added to each well and incubated at 37℃for 3h in the absence of light. The 96-well plate was removed, 70. Mu.l of the upper orange liquid was pipetted from each well into a new 96-well plate, and the absorbance (OD 490) of each well solution at 490nm was measured using a multifunctional microplate reader. Biofilm formation rate = (OD of the group ₄₉₀ Background control OD ₄₉₀ ) /(growth control OD) ₄₉₀ Background control OD ₄₉₀ ) X 100%. Experiments were repeated three times and statistical analysis was performed using One-way anova (One-way anova) and Dunnett-t test. The results of the experiment are shown in FIG. 2, and FIG. 2 is a schematic diagram showing the results of the inhibition of the formation of the biofilm of Candida albicans SC5314 by PeAc from a concentration of 16. Mu.g/ml in example 3. Wherein the abscissa indicates the concentration of PeAc (. Mu.g/ml) and the ordinate indicates the biofilm formation rate (%). * Represents P < 0.05 and P < 0.001. The results show that the concentration of PeAc, starting from 16. Mu.g/ml, shows an effect against Candida albicans biofilm.

Example 4: determination of partial inhibitory concentration index (FICI) for combination of PeAc and fluconazole

Materials and methods

1. Reagent: peAc: purchased from Shanghai Tao Shu Biotech Co. Fluconazole: purchased from Shanghai Ala Biochemical technologies Co., ltd. Dimethyl sulfoxide (DMSO): purchased from Macklin corporation. The PeAc and fluconazole are prepared into 10mg/ml solution by DMSO, and the tested medicine is preserved at the temperature of minus 20 ℃. Before the experiment, the medicine storage liquid is taken out and put into a 35 ℃ incubator to be melted, and the medicine storage liquid is fully and uniformly mixed to respectively carry out the subsequent experiment.

2. Strains: candida albicans drug resistant strains (901, 953) are provided by the medical chemistry teaching and research laboratory of the navy medical university. The candida albicans strain is subjected to scratch activation in a sandcastle glucose agar medium (SDA), cultured for 48 hours at 35 ℃, then the monoclonal is respectively selected and subjected to scratch activation again, the monoclonal obtained in the second time is placed on an SDA inclined plane, and the culture is carried out by the method and then the culture is preserved at 4 ℃ for standby.

3. Culture solution

RPMI 1640 medium: RPMI 1640 (Gibco BRL) 10g, naHCO ₃ 2.0 34.5g (0.165M) of morpholinopropane sulfonic acid (morpholinepropanesulfonic acid, MOPS) (Sigma) are dissolved in 900ml of distilled water, the pH is adjusted to 7.0 (25 ℃) by 1NNaOH, the volume is fixed to 1000ml, filtered and sterilized, and the mixture is stored at 4 ℃.

5. FICI for measuring combination of PeAc and fluconazole by chessboard type trace liquid-based dilution method

Candida albicans was inoculated in YPD liquid medium and cultured at 30℃for 16 hours. The activated bacterial liquid is sucked into a 1.5ml centrifuge tube, centrifuged for 1min at 3000g, the culture medium is sucked and removed, the PBS is used for washing once, the supernatant is centrifuged and removed, the supernatant is resuspended in 1ml PBS, and 10 μl is taken to be counted by a blood cell counting plate after dilution. Adjusting the concentration of the bacterial liquid to 1X 10 by using RPMI 1640 culture medium ³ cells/ml. Uniformly mixing the prepared bacterial liquid and transferring to 6 holesIn the plate, 2.6ml was added to the first well and 1.3ml was added to each of the 2 nd to 6 th wells. Preparing mother solution of PeAc and FLC with DMSO, adding a certain volume of PeAc into the first well to make its final concentration 64 μg/ml, and sequentially performing sesquidilution to make the final concentration of the compound in the 1 st-6 th wells 64-2 μg/ml. The formulated PeAc-containing bacterial suspension was transferred to the A-F rows of 96-well plates at a drug concentration ranging from high to low, with 200. Mu.l/well in the first column and 100. Mu.l/well in the 2-10 columns. As a growth control, 100. Mu.l/well of a blank solution was added to each of the A11-F11 wells of column 11 and the G1-G10 wells of row G. The prepared FLC was added to the A1-G1 wells of the first column, respectively, at a final concentration of 64. Mu.g/ml. Each column was serially diluted from left to right in half to give final FLC concentrations of 64-0.25 μg/ml for columns 1-9, respectively. 100. Mu.l of RPMI 1640 medium was added to each of column 12 and row H of the 96-well plate as a blank. The 96-well plate is placed in a constant temperature incubator at 30 ℃ for static culture for 48 hours, and then OD is measured ₆₃₀ . To grow control group OD ₆₃₀ The value of (2) is 100%, and the bacteriostasis rate (%) of the compound under different drug concentrations corresponding to each hole is calculated to obtain the MIC of the PeAc and the FLC when being used singly or in combination ₈₀ The synergy index FICI is then calculated. The experimental results are shown in table 2, and table 2 is the measurement result of the partial inhibitory concentration index (FICI) of the combination of PeAc and fluconazole.

TABLE 2

Conclusion: the results in table 2 show that PeAc in combination with fluconazole has synergistic resistance against fungi. The partial inhibitory concentration index (fractional inhibitory concentration index, FICI) is the main parameter for evaluating the interaction mode of two drugs for combination. FICI calculation method: the sum of the ratio of the Minimum Inhibitory Concentration (MIC) measured when the two drugs are combined to the MIC when used alone, i.e., fici=fica+ficb= (MICA/MICA) + (MICBA/MICB), MICA and MICBA are the minimum inhibitory concentrations of drug a and drug B when the two drugs are combined, respectively, and MICA and MICB are the minimum inhibitory concentrations of drug a and drug B when used alone. The experiment selects the currently internationally recognized standard to evaluate the combined drug effect: the FICI is less than or equal to 0.5, the synergy is stronger the smaller the FICI index is; FICI is less than or equal to 1 and is 0.5, and the addition effect is achieved; fici is 1 to 4, and the effect is irrelevant; FICI >4, antagonism. The experimental result of the chessboard type trace liquid-based dilution method shows that the FICI of the combined drug of the PeAc and the fluconazole is less than 0.5 for two drug-resistant bacteria (candida albicans versus fluconazole resistant strains 901 and 953), and the combined drug of the two drugs has a synergistic effect.

Example 5: determination of inhibition zone of drug-resistant fungi by combining PeAc and fluconazole

Materials and methods

3. Culture solution

YPD solid medium containing 64. Mu.g/ml FLC: 20g of agar is additionally added on the basis of YPD liquid culture medium, filtered and sterilized FLC liquid is added when the culture medium is not scalded after high-temperature high-pressure sterilization, so that the final concentration of FLC in the culture medium is 64 mu g/ml, and then the culture medium is poured into a 90mm plate and dried for standby.

4. Instrument: constant temperature incubator (Shanghai-constant scientific instruments Co., ltd. -MJ-150-I); shaking incubator (Jiangsu Taicang laboratory equipment Co., ltd. HZ-2111K-B).

5. Experimental procedure for sheet diffusion

Candida albicans was inoculated in YPD liquid medium and cultured at 30℃for 16 hours. The activated bacterial liquid is sucked into a 1.5ml centrifuge tube, centrifuged for 1min at 3000g, the culture medium is sucked and removed, the PBS is used for washing once, the supernatant is centrifuged and removed, the supernatant is resuspended in 1ml PBS, and 10 μl is taken to be counted by a blood cell counting plate after dilution. Sterile PBS was used to adjust the bacterial concentration to 1X 10 ⁵ Taking 5ml of diluted bacterial liquid, pouring the bacterial liquid onto YPD solid culture medium containing 64 mug/ml FLC, incubating the bacterial liquid in an incubator at 30 ℃ for 0.5-1 h to enable bacteria to settle and attach on the surface of the culture medium, discarding the supernatant, and taking out the bacterial liquid after the liquid on the surface of the agar is volatilized. A sterile paper sheet (diameter: 6 mm) was placed on the solid medium, and the same volume (5. Mu.l) of the drug to be tested was added to the center of the paper sheet. The agar culture plate is inverted and incubated in a 30 ℃ incubator, after 48 hours, the formation of a bacteriostasis zone is observed, the diameter of the bacteriostasis zone is measured, and the photo is taken. The experimental results are shown in fig. 3, and fig. 3 is a schematic diagram of the measurement results of the inhibition zone of the combination of PeAc and fluconazole on the drug-resistant fungi in example 5. The results show that the combination of PeAc and fluconazole has synergistic resistance against fungi. Compared with a control paper sheet, the PeAc acts from 8 mug to 256 mug on the dishes of the two bacteria to generate obvious inhibition zones, the inhibition zones have the characteristics of no cloning growth inside and clear boundary, and the inhibition zones are increased along with the increase of the concentration of the PeAc.

Example 6: determination of dose-effect relationship of PeAc and fluconazole combined anti-drug-resistant fungi

Materials and methods

1. Reagent: peAc: purchased from Shanghai Tao Shu Biotech Co. Fluconazole: purchased from Shanghai Ala Biochemical technologies Co., ltd. Dimethyl sulfoxide (DMSO): purchased from Macklin corporation. PeAc was prepared as a 10mg/ml solution in DMSO and the test drug was stored at-20deg.C. Before the experiment, the medicine storage liquid is taken out and put into a 35 ℃ incubator to be melted, and the medicine storage liquid is fully and uniformly mixed for the subsequent experiment.

2. Strains: candida albicans drug-resistant strain 901 is provided by the medical chemistry teaching and research laboratory of the navy medical university. The candida albicans strain is subjected to scratch activation in a sandcastle glucose agar medium (SDA), cultured for 48 hours at 35 ℃, then the monoclonal is respectively selected and subjected to scratch activation again, the monoclonal obtained in the second time is placed on an SDA inclined plane, and the culture is carried out by the method and then the culture is preserved at 4 ℃ for standby.

3. Culture solution

5. Determination of fungal growth curve

Candida albicans was inoculated in YPD liquid medium and cultured at 30℃for 16 hours. The activated bacterial liquid is sucked into a 1.5ml centrifuge tube, centrifuged for 1min at 3000g, the culture medium is sucked and removed, the PBS is used for washing once, the supernatant is centrifuged and removed, the supernatant is resuspended in 1ml PBS, and 10 μl is taken to be counted by a blood cell counting plate after dilution. Before starting culture, undiluted stock solution was added to the first row A1-C1 wells (three wells) of a 96-well plate at 200. Mu.l/well, and 100. Mu.l RP was added to each of the 2 nd-10 th rowsMI 1640 liquid medium was diluted from the first column to the 10 th column at a double ratio, and OD of each well was measured ₆₃₀ And according to the different OD of each well ₆₃₀ The value (x) and its corresponding bacterial concentration (y) are plotted to obtain a standard curve. Then the bacteria liquid is diluted by RPMI 1640 liquid culture medium and adjusted to 1 multiplied by 10 ⁶ cells/ml. The bacterial liquid was divided into several parts and transferred to 50ml centrifuge tubes, 10ml per tube. The medicines to be tested PeAc with different concentrations (2, 4 and 8 mug/ml) are respectively added into each tube of bacterial liquid, and then FLC with different concentrations (4, 16 and 64 mug/ml) are respectively added into a plurality of tubes with 2 mug/ml PeAc, and the same operation is carried out on a plurality of tubes with 4 and 8 mug/ml PeAc. Finally, 3 tubes remained, one tube was only charged with 8. Mu.g/ml PeAc, one tube was only charged with 64. Mu.g/ml FLC, and one tube was not charged. All centrifuge tubes containing bacterial liquid are cultured in a shaking incubator at a constant temperature of 30 ℃ under shaking at 200rpm, 100 μl of each bacterial liquid is respectively sucked into each group of bacterial liquid at 0, 2, 4, 8 and 12 hours, and OD of each well is measured in a 96-well plate (the bacterial liquid is uniformly mixed by vortex before taking out) ₆₃₀ The bacterial concentration at each set of different culture time nodes was calculated using the equation fitted by standard curve and plotted against time at log10 CFU/ml. The experimental results are shown in fig. 4, and fig. 4 is a schematic diagram of the measurement results of the dose-effect relationship of PeAc and fluconazole combined anti-drug-resistant fungi in example 6.

The results show that fluconazole alone (64 mug/ml) or PeAc alone (8 mug/ml) has a certain effect of inhibiting the growth of candida albicans after 8 hours, and the inhibiting effect is rapidly weakened after 12 hours, so that the growth condition of candida albicans is similar to that of a control group. When the concentration of the immobilized PeAc is 2 mug/ml, the concentration of the immobilized PeAc is combined with 4, 16 and 64 mug/ml fluconazole, and the inhibition effect of the synergistic effect of the two medicines on drug-resistant bacteria is increased along with the increase of the concentration of the fluconazole, but the difference of the inhibition effects in groups is not obvious. The ability of the two drugs to inhibit the growth of the drug-resistant bacteria is gradually enhanced along with the increase of the concentration of the PeAc, especially when the concentration of the PeAc reaches 8 mug/ml, the drug-resistant bacteria are combined with 4, 16 and 64 mug/ml fluconazole, the effect of inhibiting the growth of the drug-resistant bacteria by the combination of the two drugs is found to be obvious, the difference of the inhibition effects in the group is obvious, and especially the combination of PeAc 8 mug/ml and FLC 64 mug/ml enables the growth of the drug-resistant bacteria to be inhibited at a lower level. Therefore, the synergistic antifungal effect of the two medicines is more obvious in relation to the quantity effect of the PeAc.

Example 7: determination of antifungal action in PeAc

Materials and methods

1. Reagent and main reagent: peAc: purchased from Shanghai Tao Shu Biotech Co. Dimethyl sulfoxide (DMSO): purchased from Macklin corporation. PEG300: purchased from Shanghai Taitan technologies Co., ltd; tween-80: purchased from Shanghai Taitan technologies Co., ltd; physiological saline: purchased from Shandong Qi pharmaceutical Co., ltd; cyclophosphamide: purchased from Baxter Oncology GmbH company; levofloxacin lactate: shanghai Ala Biochemical technology Co., ltd; PBS: purchased from Shanghai Biotechnology.

The PeAc is prepared into 200mg/ml mother liquor by DMSO, and the tested medicine is preserved at-20 ℃. Before the experiment, the medicine storage liquid is taken out and put into a 35 ℃ incubator to be melted, fully and uniformly mixed, and the in-vivo experiment is carried out after dilution.

The drug solution to be administered to mice was prepared into a solution of the target administration concentration at a ratio of 10% DMSO, 40% PEG300, 5% Tween-80, and 45% physiological saline per ml.

The liquid medicine to be administered to the larva of Chilo suppressalis is diluted with normal saline to each administration concentration (DMSO content is not more than 5%).

3. Culture solution

4. Animals: the mice used in the experiments were clean ICR strain mice purchased from Jiangsu Hua Xinnuo medical science and technology Co., ltd, all purchased at 4-6 weeks old and weighing 18-22g.

Wax moth larvae used in the experiments were purchased from a world-climbing company and weighed about 0.5g.

5. Instrument: constant temperature incubator (Shanghai-constant scientific instruments Co., ltd. -MJ-150-I); shaking incubator (Jiangsu Taicang laboratory equipment Co., ltd. HZ-2111K-B).

6. In vivo experiments

Model of gastrointestinal infection with candida albicans in mice: healthy female ICR mice of 18-22g weight, 4-6 weeks old, were fed adaptively for 3d and the experiment was started. Two days before molding, the mice were intraperitoneally injected with 100mg/kg cyclophosphamide to be in an immunosuppressive state, and the drinking water of the mice was changed to an aqueous solution containing 0.4mg/ml levofloxacin. Candida albicans was inoculated in YPD liquid medium and cultured at 30℃for 16 hours. Sucking activated bacterial liquid into a 1.5ml centrifuge tube, centrifuging at 3000g for 1min, washing with PBS once after sucking and removing culture medium, centrifuging, removing supernatant, re-suspending with 1ml PBS, diluting, collecting 10 μl to blood cell counting plate, and regulating bacterial concentration to 1×10 with physiological saline injection ⁹ cells/ml, mice bacterial liquid 0.4 ml/day (4×10) ⁸ cells/alone) at which point it was recorded as day 0 of observation. After 2h of sterilization, cyclophosphamide is injected into the abdominal cavity of each group of mice, and then each group of mice is irrigated with 0.2 ml/mouse of different concentration of drugs, and the control group is irrigated with physiological saline containing 1% DMSO. The cyclophosphamide was injected in supplementary form on days 3 and 6 of the observation period. Mice survived were recorded daily for 10 days of dosing, survival curves were drawn and Log-rank statistical analysis was performed using GraphPad Prism software. The experimental results are shown in fig. 5, and fig. 5 is a schematic diagram showing the result that PeAc in example 7 effectively improves the survival rate of candida albicans infected mice. * Represents P < 0.05, and P < 0.01. The results show that the survival rate of mice can be obviously improved by 16mg/kg (P is less than or equal to 0.05) and 32mg/kg (P is less than or equal to 0.01) of PeAc. It was demonstrated that PeAc was able to protect candida albicans infected mice, exhibiting antifungal activity in vivo.

Model of candida albicans infection with wax borer: candida albicans (WT and FBA1 single allele knock-out) was inoculated in YPD liquid medium and cultured at 30℃for 16 hours. Sucking the activated bacterial liquid into a 1.5ml centrifuge tubeCentrifugation at 3000g for 1min, washing with PBS once after pipetting off the medium, centrifuging off the supernatant, resuspension with 1ml PBS, dilution and counting 10. Mu.l to a blood cell count plate. Adjusting the concentration of the bacterial liquid to 1X 10 by using sterile PBS ⁸ cells/ml. 16 healthy wax moth larvae with similar sizes are placed in the same plate, and the average weight of the worms is calculated. Mu.l of bacterial liquid is injected at the last leg of the left side of the wax moth larva, and then 5 mu.l of medicines (DMSO less than or equal to 1.5 mu.l) with different concentrations (8, 16 and 32 mg/kg) are injected in the last leg of the right side. The syringe was washed sequentially in ethanol and water before and after use. After injection, the wax moth larvae are cultured in a constant temperature incubator at 37 ℃, death conditions of the wax moth larvae are observed every day, the continuous observation is carried out for 10 days, survival curves are drawn, and Log-rank statistical analysis is carried out by using GraphPad Prism software. The experimental results are shown in FIG. 19. The survival time of the FBA1 delta/FBA 1 infected wax moth larvae was prolonged compared to WT, but still the mortality rate at day 2 of the observation period was over 80%. For both WT and FBA1 delta/FBA 1 infected larvae, peAc 32mg/kg significantly improved larval survival, but 32mg/kg PeAc treatment resulted in 50% FBA1 delta/FBA 1 infected wax moth larvae survival, whereas WT infected wax moth larvae survival was only 25% from the final number of larvae surviving. The effect of PeAc treatment on improving the survival rate of fba1Δ/FBA1 infected wax moth larvae is stronger than that of wild type bacteria infected wax moth larvae.

Example 8: cytotoxicity assay of PeAc

Materials and methods

1. Reagent and main reagent: peAc: purchased from Shanghai Tao Shu Biotech Co. Dimethyl sulfoxide (DMSO): purchased from Macklin corporation. CCK-8: purchased from Shanghai Tao Shu Biotech Co. PeAc was prepared as a 10mg/ml solution in DMSO and the test drug was stored at-20deg.C. Before the experiment, the medicine storage liquid is taken out and put into a 35 ℃ incubator to be melted, and the medicine storage liquid is fully and uniformly mixed for the subsequent experiment.

2. Cell lines: human Umbilical Vein Endothelial Cells (HUVEC) (available from ATCC). HUVEC cells were cultured in complete medium (DMEM+10% foetal calf serum) at 37 ℃.

3. Culture solution: DMEM high sugar medium: purchased from Shanghai Taitan technologies Co. Fetal bovine serum: purchased from the company of Hangzhou biotechnology, inc. on the Zhejiang day. Pancreatic enzyme: purchased from Shanghai Taitan technologies Co.

4. Instrument: constant temperature incubator (Shanghai-constant scientific instruments Co., ltd. -MJ-150-I); multifunctional enzyme labeling instrument (TECAN Infinite M200).

5. Configuration of cell dosing plate

Cultured Human Umbilical Vein Endothelial Cells (HUVECs) were taken, after pancreatin digestion, cells were collected by centrifugation and resuspended in complete medium. Cell density was adjusted to 5X 10 after counting by a cytometer ⁴ cells/ml. The 96-well plate is taken to divide an experimental area, a control area and a cell-free area. 100. Mu.l of cell fluid was added to each well of the experimental and control areas, and 100. Mu.l of complete medium was added to the cell-free area. Care was taken to make the cell distribution in the wells as uniform as possible. Cells were attached overnight in an incubator at 37 ℃. The next day, sterile EP tubes were taken and the drug to be tested was diluted in a double ratio with complete medium to a final drug concentration of 64-8. Mu.g/ml. The 96-well plate was then removed and the original medium was aspirated from the experimental and control areas. Mu.l of medium containing different concentrations of drug was added to each well (three wells per concentration) and incubation was continued for 24h at 37 ℃. The 96-well plate was removed, and the original medium in the experimental, control and cell-free areas was aspirated, and 110. Mu.l of complete medium containing CCK-8 (CCK-8: complete medium=1:10) was added to each well and incubated at 37℃for 2 hours. Measuring OD of each well ₄₅₀ . The OD value of the Cell-free zone was subtracted from the OD value of the experimental zone and the OD value of the control zone at the time of treatment, and the Cell-based mobility of each group was calculated to be 1.0. Experiments were repeated 3 times, plotted with GraphPad and analyzed statistically. The results of the experiment are shown in FIG. 6, and FIG. 6 is a schematic diagram of the cytotoxicity results of PeAc in example 8. Wherein the abscissa indicates the concentration of PeAc (. Mu.g/ml) and the ordinate indicates the cell activity (%). * And P < 0.0001. The results show that the PeAc shows obvious toxicity only when the PeAc concentration is as high as 64 mug/ml, which shows that the antifungal effect of the PeAc has certain specificity and has relatively low toxicity to human cells.

Example 9: establishment of candida albicans monoallel gene knockout bacteria library

The invention autonomously constructs a candida albicans gene knockout bacteria library, and the method for mature establishment of the early gene knockout application period is as follows: SAT1 flip per gene knock-out (Future microbiol.2018, 13:1141-1156.). The method utilizes the nourseothricin (nourseothricin) resistance marker to screen positive clones (the nourseothricin resistance gene can be completely removed in subsequent experiments), can avoid the interference of an auxotrophin marker gene on candida albicans, and the gene knockout strain is used for subsequent research and has reliable characters. The method achieves the aim of gene knockout based on the homologous recombination principle, and can avoid the off-target effect.

Materials and methods

1. Reagent and main reagent: sanPrep column type plasmid extraction kit: purchased from Shanghai Biotechnology. Ampicillin trihydrate (AMP): purchased from Shanghai Biotechnology. DNA molecular weight standard Marker: purchased from Shanghai Biotechnology. Restriction enzyme SacI: purchased from NEB New England Biolabs. Restriction enzyme ApaI: purchased from NEB New England Biolabs. Yeast transformation kit: purchased from Shanghai Kangshen Biotech Co. Noralserin: purchased from Shanghai Kangshen Biotech Co. 10×te Buffer: purchased from beijing tianen biotechnology limited. Ex Taq: purchased from TaKaRa Biotechnology (Dalian) co. Low electroosmotic agarose: purchased from Shanghai Kamong Biotechnology Co. Nucleic acid dye Super Red: purchased from biosharp.50×TAE: purchased from biosharp. DNA Loading Baffer: purchased from Vazyme Biotech Co., ltd.

3. Culture solution

Noralserin solid medium plate: 20g of agar was added on the basis of YPD liquid medium, after autoclaving the medium was cooled to about 50℃and a solution of filter sterilized Noralserin was added to give a final Noralserin concentration of 200. Mu.g/ml in the medium, which was then poured into a 90mm dish and dried for use.

LB liquid medium: weighing 20g of LB culture medium powder, adding triple distilled water to a volume of 1L, sterilizing at high temperature and high pressure, and storing in a refrigerator at 4 ℃.

4. Instrument: clean bench (Jiangsu Antai air technologies Co., ltd. SW-CJ-1 FD); constant temperature incubator (Shanghai-constant scientific instruments Co., ltd. -MJ-150-I); a mini centrifuge (Hitachi CT15 RE); electric water bath (Hualian medical instruments Co., ltd., DK-8D); shaking incubator (Jiangsu Taicang laboratory equipment Co., ltd. HZ-2111K-B); gel imager (Shanghai tenability Tanon 2500R); level electrophoresis apparatus (Shanghai taitan technology Co., ltd HE-130).

5. Construction of monoallelic knockout bacterium by SAT1 flip per knockout method

The candida albicans wild type SC5314 is taken as a parent strain, a target gene is replaced by cassette (containing a noscapillin resistance marker caSAT 1) through two homologous recombination, and the cassette contains candida albicans adaptive FLP fragments and can be completely deleted, so that the knockout strain with the deletion of the target gene is finally obtained. The specific process is as follows: 250 bases (total 500 bases) on the inner side and outer side of the ORF of the target gene are selected upstream, and cloned into the MAL2p-CaFLP-CaSAT1 cassette upstream of the pSFS2 plasmid as upstream homology arms, and likewise 250 bases (total 500 bases) on the inner side and outer side of the ORF of the target gene are selected downstream, and cloned into the MAL2p-CaFLP-CaSAT1 cassette downstream as downstream homology arms, thus constructing the pSFS2- "target gene" updwn plasmid. The function of the two homology arms is to help knockout plasmids to realize homologous recombination with the target gene. After the pSFS2- "target gene" updwn plasmid was obtained, it was double digested with two restriction enzymes ApaI and SacI. The cut fragment is transformed into candida albicans SC5314 by a lithium acetate method, and then one allele of the target gene is replaced by the fragment in a homologous recombination mode. A plurality of primers are used for identifying a transformant which shows resistance to the nociceptin through colony polymerase chain reaction, and the single-allele knockout bacteria of the target gene can be obtained after deleting the nociceptin resistance marker (CaSAT 1) from the correct transformant.

The experimental results are shown in figures 7, 8 and 9; FIG. 7 is a schematic diagram of the strategy for creating a pool of single allele knock-outs of Candida albicans in example 9, which demonstrates the principle of homologous recombination and the nociceptin resistance gene SAT1 utilized for gene knock-out. And (3) identifying whether gene knockout is successful or not by using a nested PCR, wherein the design idea of nested PCR primers is shown in the figure.

FIG. 8 is a schematic diagram of the implementation of the construction of a pool of single allele knock-outs of Candida albicans in example 9, with the combined diagram from left to right: primer information, predicted band size and agarose gel electrophoresis results of nested PCR verification after the candida albicans ARO1 single allele knockout. According to the fact that the sizes of 5 bands of the ARO1 single allele knocked-out bacteria detected in the agarose gel electrophoresis result diagram on the right side of the combined diagram are consistent with the corresponding predicted band sizes, the candida albicans ARO1 single allele is proved to be knocked out successfully.

FIG. 9 is a schematic representation of the implementation of the establishment of a pool of single allele knock-outs of Candida albicans in example 9. Taking candida albicans FBA1 gene as an example, the combined graph is from left to right: primer information, predicted band size and agarose gel electrophoresis results of nested PCR verification after the single allele knockout of candida albicans FBA 1. According to the right agarose gel electrophoresis result diagram of the combined diagram, the 5 band sizes of the tested FBA1 single allele knockout bacteria are consistent with the corresponding predicted band sizes, and the successful knockout of the candida albicans FBA1 single allele is proved. The results show that candida albicans single allele knock-out bacteria can be successfully constructed by using the SAT1 flip er knock-out method.

Example 10: compound target screening based on haploid deficiency effect analysis

The invention firstly confirms that the haploid deficiency effect can be used for identifying antifungal drug targets. The known action targets of the azole drugs such as fluconazole, itraconazole, voriconazole and the like are ERG11, and spot plate experiments and MIC experiments are carried out by utilizing candida albicans (erg1Δ/ERG 11) with single allele knocked out of ERG11 and wild type parent bacteria SC5314 (WildType, WT), and the experimental results are consistent to show that: the sensitivity of the strain lacking one allele of ERG11 to three azole drugs of fluconazole, itraconazole and voriconazole is obviously increased, and the strain completely accords with the haploid deficiency effect. The results are shown in FIGS. 10 and 11.

The invention further examines the special characteristics of the haploid deficiency effect applied to the identification of antifungal drug targets. Given that the action target of the azole drugs such as fluconazole, itraconazole, voriconazole and the like is ERG11, the single allele knockout bacteria of other genes except the ERG11 gene should not show special sensitivity to the azole drugs. Multiple gene (FBA 1, ARO1 and the like) knockdown bacteria are selected to examine the sensitivity of the bacteria to azole drugs. Experiments include spot plate experiments and MIC experiments. The research finds that: the sensitivity of the strain lacking one FBA1 (or ARO1, etc.) allele to azole drugs is unchanged, and the identification of the haploid deficiency effect drug target has specificity, and the results are shown in figures 12 and 13.

In view of the fact that identification of drug targets is sensitive and specific by using haploid deficiency effect, the invention researches the action targets of PeAc by using an autonomously constructed candida albicans gene knockout bacteria library. Strains deleted for single allele were extensively screened for sensitivity to PeAc (micropluid dilution and spot plate assay), and it was found that only strains deleted for one FBA1 allele exhibited increased sensitivity to PeAc, suggesting that FBA1p is the action target of PeAc (results shown in fig. 14) and is the specific action target of PeAc (results shown in fig. 15).

Materials and methods

1. Reagent and main reagent: peAc: purchased from Shanghai Tao Shu Biotech Co. Fluconazole: purchased from Shanghai Ala Biochemical technologies Co., ltd. Dimethyl sulfoxide (DMSO): purchased from Macklin corporation. PeAc was prepared as a 10mg/ml solution in DMSO and the test drug was stored at-20deg.C. Before the experiment, the medicine storage liquid is taken out and put into a 35 ℃ incubator to be melted, and the medicine storage liquid is fully and uniformly mixed for the subsequent experiment.

2. Strains: ATCC standard strain: candida albicans (Candida albicans) SC5314 (commercially available from ATCC). All experimental candida albicans single allele knock-out parent bacteria were SC5314. All experimental strains are subjected to streak activation on a sandcastle glucose agar medium (SDA), candida albicans is cultured for 48 hours at 35 ℃, then monoclonal is selected and subjected to streak activation again, the monoclonal obtained in the second time is placed on an SDA inclined plane, and the culture is carried out by the method and then the culture is preserved at 4 ℃ for standby.

3. Culture solution

YPD solid medium is added with 20g of agar on the basis of liquid medium, and poured into a 90mm dish after autoclaving, and dried for standby.

5. Experimental procedure

Trace liquid-based dilution method: the procedure is as in example 1.

Dot plate test method: candida albicans was inoculated in YPD liquid medium and cultured at 30℃for 16 hours. The activated bacterial liquid is sucked into a 1.5ml centrifuge tube, centrifuged for 1min at 3000g, the culture medium is sucked and removed, the PBS is used for washing once, the supernatant is centrifuged and removed, the supernatant is resuspended in 1ml PBS, and 10 μl is taken to be counted by a blood cell counting plate after dilution. Adjusting the bacterial concentration to 3×10 with PBS ⁶ cells/ml. Preparing serial dilutions of WT and each haploid knockout bacterium, and diluting the serial dilutions to 10-fold ratio5 concentrations of each Candida albicans serial concentration dilution was spotted on YPD agar plates to which different concentrations of the drugs to be examined were added in advance, inverted in a constant temperature incubator, cultured at 35℃for 24-48 hours, during which the difference in growth between the strains was observed and recorded by photographing.

Molecular docking: the mode of action of PeAc and Fba1p was analyzed in silico.

The experimental results are shown in fig. 10-16, and fig. 10 is a schematic diagram showing the results of a plating experiment in feasibility verification of application of haploid deficiency effect in antifungal drug target identification in example 10, and the known effect target of azole drugs such as fluconazole, itraconazole, voriconazole and the like is ERG11, and the results show that the sensitivity of the ERG11 single allele knock-out candida albicans (ERG 11 delta/ERG 11) to fluconazole, itraconazole and voriconazole is obviously improved compared with the Wild Type parent strain SC5314 (Wild Type, WT) and completely accords with the haploid deficiency effect.

Fig. 11 is a schematic diagram of MIC experimental results in the feasibility verification of haploid deficiency effect in antifungal drug target identification in example 10, the results are presented in a thermogram format, and the results also show that ERG11 single allele knock-out candida albicans (erg1Δ/ERG 11) has increased sensitivity to fluconazole, itraconazole, voriconazole compared to its Wild-Type parent strain SC5314 (Wild Type, WT), and also accords with the haploid deficiency effect. The results of fig. 10, 11 together demonstrate that the haploid deficiency effect is viable and effective for antifungal drug target identification.

FIG. 12 is a schematic of the results of a spot-plating experiment in a proprietary verification of the use of the haploid deficiency effect in the identification of antifungal drug targets in example 10. Given that the action target of the azole drugs such as fluconazole, itraconazole, voriconazole and the like is ERG11, the single allele knockout bacteria of other genes except the ERG11 gene should not show special sensitivity to the azole drugs. The results show that there is no significant difference in the sensitivity of other (e.g., FBA1, ARO1, KGD1, ENO 1) single allele knockouts candida albicans versus their Wild-Type parent bacteria SC5314 (Wild Type, WT) to fluconazole, itraconazole, voriconazole.

FIG. 13 is a schematic representation of the results of MIC experiments in which the haploid deficiency effect of example 10 was used in the specific validation of antifungal drug target identification. The results also show that there is no significant difference in the sensitivity of other (e.g., FBA1, ARO1, KGD1, ENO 1) single allele knockouts of candida albicans compared to its Wild-Type parent strain SC5314 (Wild Type, WT) to fluconazole, itraconazole, voriconazole. The results of FIGS. 12 and 13 together demonstrate that strains of alleles other than the ERG11 gene are unchanged in sensitivity to azole drugs, demonstrating that haploid deficiency effect identification targets are proprietary.

FIG. 14 is a schematic of the results of the spot plate and MIC experiments of example 10 in which haploid deficiency effects were used for PeAc target screening, demonstrating that the sensitivity of FBA1 single allele knock-out Candida albicans (fba1Δ/FBA 1) to PeAc was increased compared to its Wild-Type parent strain SC5314 (Wild Type, WT), suggesting that Fba1p is the target of action of PeAc.

FIG. 15 is a schematic diagram of the results of the spot plate experiment and MIC experiment of example 10 in which haploid deficiency effect was applied to PeAc target screening, showing that there was no significant difference in sensitivity contrast of other (e.g., ARO1, KGD1, ENO 1) single allele knock-outs candida albicans and its Wild-Type parent strain SC5314 (Wild Type, WT) to PeAc, suggesting that Fba1p is a specific acting target for PeAc.

FIG. 16 is a schematic representation of the results of examining the mode of action of PeAc and Fba1p by molecular docking in example 10. The results in FIG. 16 show that the carboxyl group of cis-6-octadecenoic acid (PeAc) forms three hydrogen bonds with the surrounding amino acid residues Ser267, thr288, asp289, respectively, and the alkane chain forms a hydrophobic effect with the surrounding amino acid residues such as Asn35, his109, gly265, his 225.

Example 11: investigation of the action of PeAc on antifungal action by Fba1p

The present invention verifies that PeAc exerts antifungal effects through Fba1p by examining liquid hyphae formation (same as example 2), biofilm formation (same as example 3) and in vivo survival (same as example 7).

The experimental results are shown in fig. 17 to 19: FIG. 17 is a schematic diagram showing the results of verification of the inhibition of hypha formation by PEAc exerting antifungal effect through Fba1p in example 11. The results show that both candida albicans (WT and fba1Δ/FBA 1) form hyphae in the hyphae induction medium without drug action. PeAc at a concentration of 1. Mu.g/ml significantly inhibited FBA 1. Delta./FBA 1 hyphae formation, even when yeast cells were observed. In the case of wild-type (WT) bacteria, however, 1. Mu.g/ml PeAc does not allow the hyphae of the wild-type bacteria to be shortened. Demonstrating that the sensitivity of FBA1 single allele knock-out candida albicans (FBA 1 delta/FBA 1) to PeAc is increased compared to its Wild-Type parent strain SC5314 (Wild Type, WT), indicating that FBA1p is the target of action of PeAc.

FIG. 18 is a schematic diagram showing the results of inhibition of biofilm formation by PeAc exerting antifungal effect through Fba1p in example 11. The results show that PeAc can reduce the rate of candida albicans biofilm formation in a dose-dependent manner. 16 μg/ml of PeAc inhibited biofilm formation by WT bacteria with an inhibition rate of approximately 34.12% (#P < 0.05). Whereas for FBA1 delta/FBA 1,8 μg/ml PeAc achieved the above 16 μg/ml PeAc inhibition effect against WT bacteria with an inhibition rate of about 34.07% (. Times.p < 0.05). When the PeAc concentration was increased to 16 μg/ml, the biofilm inhibition rate for FBA1 delta/FBA 1 bacteria reached 50.43% (< 0.001 in P). Demonstrating that the sensitivity of FBA1 single allele knock-out candida albicans (FBA 1 delta/FBA 1) to PeAc is increased compared to its Wild-Type parent strain SC5314 (Wild Type, WT), indicating that FBA1p is the target of action of PeAc.

FIG. 19 is a schematic representation of the results of the survival experiments of wax moth larvae in example 11 where PeAc exerts antifungal effect through Fba1 p. The results in FIG. 19 show that the survival time of the FBA1 delta/FBA 1-infected wax moth larvae was prolonged compared to WT, but still the mortality was over 80% at day 2 of the observation period. For both WT and FBA1 delta/FBA 1 infected larvae, peAc 32mg/kg significantly improved larval survival, but 32mg/kg PeAc treatment resulted in 50% FBA1 delta/FBA 1 infected wax moth larvae survival, whereas WT infected wax moth larvae survival was only 25% from the final number of larvae surviving. Demonstrating that the sensitivity of FBA1 single allele knock-out candida albicans (FBA 1 delta/FBA 1) to PeAc is increased compared to its Wild-Type parent strain SC5314 (Wild Type, WT), indicating that FBA1p is the target of action of PeAc.

The above results all demonstrate that PeAc exerts an antifungal effect through Fba1 p. Fructose-1, 6-bisphosphate aldolase (Fba 1 p) is a drug target for PeAc, which is a fructose-1, 6-bisphosphate aldolase inhibitor.

The foregoing description is only illustrative of the preferred embodiment of the present invention, and is not to be construed as limiting the invention, but is to be construed as limiting the invention to any and all simple modifications, equivalent variations and adaptations of the embodiments described above, which are within the scope of the invention, may be made by those skilled in the art without departing from the scope of the invention.

Claims

1. Application of cis-6-octadecenoic acid or its medicinal salt in preparing antifungal medicine is provided.

2. Use of cis-6-octadecenoic acid or a pharmaceutically acceptable salt thereof according to claim 1 for the preparation of an antifungal agent, wherein the structure of the cis-6-octadecenoic acid is as follows:

3. use of cis-6-octadecenoic acid or a pharmaceutically acceptable salt thereof according to claim 1 for the preparation of an antifungal drug, wherein the fungus is selected from candida albicans, candida krusei, candida tropicalis, trichophyton mentagrophytes.

4. Application of cis-6-octadecenoic acid or pharmaceutically acceptable salt thereof in preparing antifungal medicines in cooperation with clinically common antifungal medicines is provided.

5. The use of cis-6-octadecenoic acid or a pharmaceutically acceptable salt thereof according to claim 4 in combination with a clinically usual antifungal drug for the preparation of an antifungal drug, wherein the clinically usual antifungal drug is selected from the group consisting of fluconazole, ketoconazole, itraconazole, amphotericin B, caspofungin, terbinafine.

6. Use of cis-6-octadecenoic acid or a pharmaceutically acceptable salt thereof according to claim 4 in combination with clinically usual antifungal agents for the preparation of antifungal agents, wherein the fungus is selected from candida albicans, candida krusei, candida tropicalis and trichophyton mentagrophytes.

7. Use of cis-6-octadecenoic acid or its pharmaceutically acceptable salt in preparation of fructose-1, 6-bisphosphate aldolase inhibitor is provided.