CN114249638A - Magnolol derivative containing halogen group and application thereof in resisting parasitic protozoa of fishes - Google Patents

Abstract

The invention discloses a magnolol derivative containing halogen group and application thereof in resisting fish parasitic protozoa. The invention synthesizes a series of magnolol derivatives containing halogen groups, such as a compound dibromoethoxy magnolol prepared by the halogenation reaction of magnolol and 1-bromopropane in an alkaline environment. The derivatives take magnolol as a raw material, have low toxicity to fish, can improve the killing activity to the ichthyophthirius multifiliis, have simple synthesis method and high yield, and are convenient to popularize and apply.

Description

Magnolol derivative containing halogen group and application thereof in resisting parasitic protozoa of fishes

Technical Field

The invention relates to a halogenated magnolol derivative, in particular to preparation of magnolol derivatives containing halogen groups such as dibromoethoxy magnolol and the like and application of the magnolol derivatives in killing parasitic protozoa of fishes.

Background

The fish diseases are one of the main obstacles for realizing high yield and high efficiency of aquaculture in current fishery production, wherein the fish parasitic diseases are the types with highest morbidity and most serious harm. Statistical data indicate that the parasitic disease accounts for 24.58% of 118 biogenic diseases of fish, wherein the fish parasitic protozoa disease is a type which is easy to outbreak and seriously harmful. The etiological agents of fish parasitic protozoa are parasitic protozoa, including the six phyla sarcophaga (sarcophaga), Apicomplexa (Apicomplexa), microsporida (Microspora), ascosporota (Ascetospora), mucospoda (Myxozoa) and cilia (Ciliophora). Among them, the Trichodina, Cucumis spinulosa (abbreviated as Cucumis spinulosa) and myxosporidia are species which are harmful to fish. At present, the epidemic of parasitic protozoa diseases such as ichthyophthiriasis, trichodiniasis and the like is not effectively controlled and almost occurs every year, so that a great amount of fish death is caused and huge economic loss is caused; in addition, these parasitic protozoal diseases have also severely affected the development of ornamental aquaculture fisheries. Therefore, the prevention, control and treatment of the parasitic protozoal disease have important social significance and economic value.

The currently commonly used clinical protozoon-killing fishery drugs mainly comprise zinc sulfate, copper sulfate, robenidine hydrochloride, diclazuril and the like, and increasingly outstanding drug resistance, food safety and environmental safety problems become bottlenecks for restricting the prevention and control of parasitic protozoal diseases. Natural products such as magnolol extracted and isolated from dried bark, root bark and branch bark of Magnolia officinalis (Magnolia officinalis) belonging to the family magnoliaceae have been reported to have excellent anti-insect activity (see chinese patent CN105726522A, etc.). However, in practical application, magnolol has the defect of low therapeutic index although the anti-insect effect is obvious.

The introduction of the insect-resistant active group by a chemical structure modification method is an important way for improving the insecticidal activity, reducing the insecticidal cost and reducing the toxic and side effects. Yang et al obtained a series of azo magnolol derivatives by azo synthesis (Yang C, Zhi X, Li J, ZHa J, Xu H. Natural Products-based inductive agents 20Design, synthesis and inductive activity of novel hookiol/macromolecular azo derivative industrial Crops and Products 2015,761-767.), but these derivatives were tested to have low activity against Pectinatus pis.

Disclosure of Invention

The invention aims to provide a magnolol derivative containing a halogen group and application thereof in resisting fish parasitic protozoa.

In order to achieve the purpose, the invention adopts the following technical scheme:

a magnolol derivative, the structure of which is shown in formula I, or the derivative is a pharmaceutically acceptable salt, tautomer or stereoisomer of a compound with the structure shown in formula I:

wherein R is₁Is H, CH₂Br、CH₂Cl、(CH₂)₂Br or (CH)₂)₂Cl；R₂Is CH₂Br、CH₂Cl、(CH₂)₂Br or (CH)₂)₂Cl。

The preparation method of the magnolol derivative comprises the following steps:

halogenating magnolol and halohydrocarbon under alkaline condition, extracting, drying organic phase, concentrating, performing column chromatography and drying (removing mobile phase solvent) after reaction to obtain magnolol derivative (specifically halogen-containing group magnolol derivative such as bisbromoethoxy magnolol shown in formula I) with single hydroxyl hydrogen atom substituted or two hydroxyl hydrogen atoms substituted simultaneously, wherein the halohydrocarbon is CH₃(CH₂)_nX, wherein n is 1, 2, X is Br, Cl.

Preferably, the reaction temperature is 80-100 ℃, and the reaction time is 12-24 h; the molar ratio of magnolol to halogenated hydrocarbon is 1: 5-1: 10.

Preferably, the alkaline reagent used in the reaction is NaOH or KOH (for example, the alkaline environment may be provided by 5-10% by weight of sodium hydroxide aqueous solution); a catalyst is also adopted in the reaction, the catalyst is tetrabutylammonium bromide (TBAB) or phosphorus tribromide or other common halogenated reagents, and the mass ratio of magnolol to the catalyst is 1000: 0.09-0.2.

Preferably, the extraction reagent is dichloromethane or chloroform, the mobile phase adopted in column chromatography is a petroleum ether-dichloromethane mixed solution or a petroleum ether-chloroform mixed solution, and the volume ratio of petroleum ether to dichloromethane or petroleum ether to chloroform in the mobile phase is 2: 1-1: 1.

The magnolol derivative can be used for killing parasite on body surface (in vitro).

Preferably, the magnolol derivative is used for killing fish parasitic protozoa.

Preferably, the parasitic protozoa are selected from fish epizootic protozoa such as Pectinatus polyactii.

The magnolol derivative is used for preparing a medicament for preventing and treating parasitic diseases.

Preferably, the parasitic disease includes parasitic protozoal disease, caused by chaulmoogra, etc.

Preferably, the medicament is for external or oral administration.

The invention has the beneficial effects that:

the invention carries out new chemical structure modification and reformation on the known compound magnolol, and compared with the magnolol, the obtained magnolol derivative has obviously improved insecticidal effect and can be used as an active ingredient of an antiparasitic medicament, thereby playing a role in preventing and treating parasitic diseases (including parasitic protozoosis caused by ichthyophthirius multifiliis). The magnolol derivative disclosed by the invention is simple in synthesis, separation and application methods.

Furthermore, the invention establishes a synthetic route of the bromo (chloro) hydrocarbyl derivative by taking magnolol as a substrate, selecting common halogenating agents such as tetrabutylammonium bromide and the like as catalysts, and adopting common alkaline agents such as NaOH and the like to provide an alkaline environment. The synthetic route has high yield and the product is easy to separate and purify, and is a preferred route for preparing the compound in the formula I.

Furthermore, the invention greatly improves the killing effect of the magnolol derivative on fish parasitic protozoa (especially the chaulmoogra) by taking the bromine-containing group as an insect-resistant active group and carrying out structural modification on magnolol.

Furthermore, in the magnolol derivative, the dibromoethoxy magnolol has lower toxicity to fish, can efficiently kill the ichthyophthirius multifiliis in each life stage, and is an effective component of a novel pollution-free green fishing medicament.

Drawings

FIG. 1 shows the synthetic routes of bisbromoethoxy magnolol and bischloroethoxy magnolol.

Detailed Description

The present invention will be described in further detail with reference to the following drawings and examples. The examples are given solely for the purpose of illustration and are not intended to limit the scope of the invention.

Example 1

This example provides a chemically synthesized magnolol derivative, namely, dibromoethoxyphenoxy magnolol. Compared with magnolol, the magnolol derivative has better insect-resistant effect and relatively simple synthesis process. The application of the compound (specifically, the dibromine ethoxy magnolol) in killing fish parasitic protozoa is explained in the aspects of preparation of the compound, acute toxicity tests, pharmacological tests and the like of the fish.

(mono) bis-bromoethoxy magnolol (C)₂₂H₁₆O₂Br₂) Preparation of

1 materials and methods

1.1 materials

1.1.1 test samples

Magnolol (98%, HPLC) and tetrabutylammonium bromide (99%, HPLC) used in the tests were purchased from Shanghai Allantin Biotech Co., Ltd. Anhydrous sodium sulfate (99%, HPLC), sodium hydroxide (99%, HPLC), petroleum ether (99%, HPLC), dichloromethane (99%, HPLC), 1-bromopropane (99%, HPLC) were purchased from sienna san pu chemical reagent plant.

1.1.2 test apparatus

ALC-1100 hundredth electronic balance, beijing sidoris instruments systems ltd; KQ-500E type ultrasonic cleaner; 5-10 muL, 20-200 muL pipettor VoluMate; an RE-2000B rotary evaporator of a Yangrong biochemical instrument; its linbel QL-901 vortex oscillator; german Bruker-AM500 NMR spectrometer.

1.2 test methods

1.2.1 Synthesis, separation and purification of Bibromoethoxy magnolol

Referring to fig. 1, 1.07g of magnolol is dissolved in 10mL of NaOH solution with the mass fraction of 10%, 5 equivalents (5 times of the amount of the substance) of 1-bromopropane (the mole ratio of magnolol: 1-bromopropane is 1:5) are added into the obtained magnolol solution, 0.10mg of tetrabutylammonium bromide is added as a catalyst, the mixture is stirred and uniformly mixed at room temperature and then is refluxed at 80 ℃ for 24 hours, after the reaction is finished, a proper amount of dichloromethane is added for extraction for three times, and the lower organic phase is combined; and adding 10-20 g of anhydrous sodium sulfate into the obtained organic phase, standing, drying overnight, filtering to remove sodium sulfate solids, and then removing the reaction solvent by evaporation under reduced pressure (70 ℃, and negative pressure of 0.07 MPa) to obtain a crude product. And (3) carrying out dry loading, separating and purifying all crude products by silica gel column chromatography (petroleum ether: dichloromethane is 1:1, v/v), collecting an eluted part containing the target compound by TLC detection, and evaporating the solvent to obtain 0.258g of a tan solid product.

1.2.2 structural identification of Bibromoethoxy magnolol

And analyzing and identifying the products synthesized, separated and purified by the method through nuclear magnetic resonance to obtain a C spectrum and an H spectrum.

2 results and analysis

The product spectral data obtained by analysis are as follows:

¹H NMR(500MHz,CDCl₃)δ7.43(d,J＝1.8Hz,1H),7.39(dd,J＝8.4,2.0Hz,1H),7.15(d,J＝1.9Hz,1H),7.08(dd,J＝8.3,1.9Hz,1H),6.87(t,J＝8.2Hz,2H),6.01(dddt,J＝36.9,16.8,10.0,6.7Hz,2H),5.09(ddd,J＝28.4,14.1,5.5Hz,4H),4.35(t,J＝6.2Hz,2H),4.23(t,J＝6.2Hz,2H),3.68(t,J＝6.2Hz,2H),3.55(t,J＝6.2Hz,2H),3.47(d,J＝6.7Hz,2H),3.38(t,J＝9.1Hz,2H).¹³C NMR(126MHz,CDCl₃)δ155.09,153.53,137.74,137.21,133.61,131.69,131.30,131.04,128.77,128.55,128.21,115.85,115.64,113.60,111.41,68.91,68.26,39.58,34.66,29.56,29.49.

the data show that the dibromine ethoxy magnolol (a compound with a structure shown in a formula I-1) can be successfully synthesized by adopting a halogenation reaction:

acute toxicity test of (di) dibromoethoxy magnolol on zebra fish

1 materials and methods

1.1 materials

1.1.1 test samples

The purity of the dibromoethoxy magnolol used in the test is 99.0%, and the dibromoethoxy magnolol is prepared by aquatic animal disease laboratory of northwest agriculture and forestry science and technology university (the preparation method refers to section 1.2 in the first step). Accurately weighing 1.0g of dibromoethoxy magnolol, fully dissolving with dimethyl sulfoxide (DMSO, purchased from Simian chemical reagent factory), fixing the volume in a 100mL volumetric flask, preparing dibromoethoxy magnolol mother liquor with the concentration of 10mg/mL, and storing in a refrigerator at 4 ℃ for later use.

1.1.2 test animals

The zebra fish used in the test is purchased from the Shanxi province market of sparrow flowers and birds, and is required to be robust in constitution, consistent in specification and 0.47g in average weight. Temporarily culturing in a laboratory aquaria box for 10 days after purchase, feeding for 2 times every day, and finishing eating the special zebra fish feed (purchased in the market of sparrow flowers and birds in Shanxi province) within 10 min. And carrying out toxicity test after the test is adapted to the environmental conditions of the laboratory.

1.1.3 test apparatus

ALC-1100 hundredth electronic balance, beijing sidoris instruments systems ltd; KQ-500E type ultrasonic cleaner; a 5-10 mu L, 20-200 mu L liquid transferring device; an automatic temperature control heating rod, fishing gear factories in Zhoshan city, Zhejiang.

1.2 test methods

1.2.1 test conditions

Adding fully aerated tap water, controlling the pH to be 7.2 and the water temperature to be 23 +/-1 ℃ by adopting a still water type test method, adding the bisbromoethoxy magnolol mother liquor, fully mixing to form a bisbromoethoxy magnolol liquid medicine with a certain concentration, then adding zebra fish, and stocking 100 fish in each pot. The dissolved oxygen in water is required to be kept above 5mg/L in the whole test.

1.2.2 setting of test drug concentration

Firstly, the approximate range of the concentration of the bisbromoethoxymagnolol in the liquid medicine in the formal test, namely the concentration of the drug which can completely kill the zebra fish within 24h (6.0mg/L) and the concentration of the drug which can not die within 96h (2.5mg/L), is determined through a preliminary test. Then, on the basis of the preliminary test, eight concentration test groups of 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5 and 6.0mg/L were set in the range of the concentration of the drug solution from 2.5 to 6.0mg/L by the concentration difference (tolerance d is 0.5), and the poisoning and death of zebra fish were observed in the respective concentrations in the main test.

And (4) observing and recording the death condition of the zebra fish at any time during the test period, and if the zebra fish is found dead, immediately fishing out the zebra fish so as not to influence the water quality and the test result. The fish death judging method is that after the fish stops breathing (the gill cover stops moving), the tail handle of the fish is tapped by a glass rod or tweezers, and if the fish body does not produce any stress reaction within 3min, the fish death can be judged.

The death condition of the zebra fish under the concentration of the liquid medicine in four time periods of 12h, 24h, 48h and 96h is counted during the test period. The test period should be kept quiet to avoid any disturbance of the zebrafish as much as possible. When the mortality rate of the blank control group (drug-free group) is less than 5%, the mortality rate of the zebra fish in each time period can be uncorrected; if the mortality rate of the blank control group is more than 5%, correcting, wherein the correction formula adopts an Abbott formula; if the blank control group mortality rate reaches more than 20%, the toxicity test is carried out again after the reason is found.

Abbott formula: p ═ P' -C/1-C

P-corrected mortality, i.e. mortality caused by purer drugs

P' -test group mortality, i.e. mortality due to natural factors and drugs

C-control mortality, i.e. mortality due to natural factors

1.2.3 minimum lethal concentration Range, half Lethal Concentration (LC)₅₀)

And observing and recording the death conditions of the zebra fish in 12h, 24h, 48h and 96h, calculating the death rate, and obtaining a regression equation and a half lethal concentration (95% confidence limit) of each time period by using a Probit calculation module in SPSS 20.0 software.

1.2.4 calculation of the safe concentration of Bibromoethoxymagnolol

Calculating the safe concentration according to Turbell formula:

wherein 48h LC₅₀Half-lethal concentration at 48 hours, 24h LC₅₀Half lethal concentration at 24 hours.

2 results and analysis

2.1 poisoning of Zebra fish by Bibromoethoxy magnolol of different concentrations over different periods of time

The death condition of the zebra fish with the concentration of each test liquid medicine in 12h, 24h, 48h and 96h is shown in the table 1. In a high-concentration test group with the liquid medicine concentration of 6.0mg/L, the toxic reaction of test fishes is very obvious, abnormal performance appears about 2 hours after the medicine is taken, zebra fishes float heads out of the water surface, then the zebra fishes have slow movement and lateral wandering, paralysis begins to appear in the near future, the balance is lost, and the abdomen faces upwards and dies. In the low concentration test group with the concentration of 2.5mg/L, the zebra fish is quieter in performance, sensitive in response to the outside and normal in activity.

TABLE 1 toxic mortality results of zebrafish with varying concentrations of bisbromoethoxymagnolol

2.2 minimum lethal concentration Range, half Lethal Concentration (LC)₅₀)

The lowest concentration of zebra fish at which death begins to occur at each time period and the next concentration are the lowest lethal concentration range for that time period, and the mortality is calculated.

TABLE 2 Linear regression equation, LC for each time period₅₀And 95% confidence limit thereof

2.3 safe concentration

The regression equation, the median lethal concentration (LC50) and the 95% confidence limit for LC50 for each time period are shown in table 2. And calculating the safe concentration of the dibrominated ethoxy magnolol on the zebra fish according to a Turbell formula.

The result shows that the phenomenon of fish death does not occur within 96h under the condition that the concentration of the dibromoxyethoxy magnolol is 2.5 mg/L.

Killing effect of (III) dibromoethoxy magnolol on ichthyophthirius multifiliis

1 materials and methods

1.1 test animals

The test animals are goldfish (Carassius auratus), the weight of the test animals is less than 5.0g, and the test animals are from Changxing goldfish farms in the Yangyang city of Shaanxi province.

1.2 parasites

The multi-seed ichthyophthirius multifiliis separated from diseased goldfish in the markets of red sparrow flower and bird in Shaanxi province, and the passage mode is as follows: placing goldfish in 40L water tank at 22.0 + -2.0 deg.C, oxygenating with oxygen pump, siphoning to absorb dirt, and changing water 1/3 every other day. The method for collecting the ichthyophthirius multifiliis: several goldfish with severe parasitic ichthyophthirius multifiliis first placed in a beaker with 300mL of filtered water for 30 minutes. The goldfish continuously swims, so that the mature ichthyophthirius multifiliis shed from the body surface of the goldfish, and the shed ichthyophthirius multifiliis cysts are collected by a suction pipe. And then culturing the collected cysts at the temperature of 23.5 +/-0.5 ℃ for 18-20 h to obtain the larvae of the ichthyophthirius multifiliis. The counting method of the small melon insects comprises the following steps: using a liquid transfer machine to transfer 2 mu L of larva suspension to be placed on a glass slide, counting under a dissecting mirror, repeating ten times to obtain an average value as the concentration of the larva suspension of the ichthyophthirius multifiliis, and counting the ichthyophthirius multifiliis according to the concentration.

1.3 test drugs

The purity of the dibromoethoxy magnolol used in the test is 99.0 percent, and the dibromoethoxy magnolol is prepared by an aquatic animal disease laboratory of northwest agriculture and forestry science and technology university. The dibromine ethoxy magnolol is fully dissolved by dimethyl sulfoxide (DMSO, purchased from Simian chemical reagent factory), the volume is determined in a 100mL volumetric flask, and a dibromine ethoxy magnolol mother liquor with the concentration of 10mg/mL is prepared and stored in a refrigerator at 4 ℃ for later use.

1.4 Bibromoethoxy magnolol killing larvae of Cucumis melo

The killing effect of the dibromoethoxy magnolol on the larvae of the ichthyophthirius multifiliis is determined by a fixation method. 300 larvae were placed in each well of a 96-well plate. Then the mother liquor of the dibromine ethoxy magnolol is put in sequence, so that the final concentration of the medicine reaches 0, 0.05, 0.1, 0.2, 0.3, 0.5, 0.7 and 0.8mg/L respectively. Dead larvae of the melon were then observed and recorded at 4h with a dissecting scope. Abnormal or immotile larvae were considered dead. The whole experiment was carried out at 23.5 + -0.5 deg.C and repeated 3 times with larvae of the ichthyophthirius multifiliis grown in different hosts at different times.

1.5 Bibromoethoxy magnolol capsule for killing ichthyophthirius multifiliis

30 Pectinatus cantoniensis capsules (with the volume of 1mL) are placed in each hole of a 24-hole plate, and then the dibromoethoxyphyllophora mother liquor is sequentially placed to enable the final concentration of the medicine to reach 0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0 and 1.2mg/L respectively. The 24-well plate was incubated in an incubator (23.5. + -. 0.5 ℃ C.). And (4) taking out the 24-hole plate after 18-20 h, recording dead watermelon cysts under a dissecting mirror, counting the number of the larvae of the watermelon, calculating the reproduction rate of the watermelon (the number of the larvae of the watermelon in each hole/the number of the surviving watermelon cysts) according to the number of the larvae of the watermelon, and repeating the whole test for 3 times.

2 results and analysis

2.1 Effect of Bibromoethoxy magnolol on killing larvae of Cucumis melo

The effect of different concentrations of dibromoethoxyphenol on killing larvae of ichthyophthirius was shown in table 3. The results show that: when the concentration of the dibromoethoxy magnolol is more than 0.40mg/L, the larva of the ichthyophthirius multifiliis can be killed by 100 percent. Calculated, the half lethal concentration of the dibromoethoxyphenol for killing the larvae of the ichthyophthirius multifiliis 0.157mg/L (the confidence interval of 95 percent is 0.13-0.188 mg/L) at 4 h. It was also found that a concentration of 0.40mg/L or higher of dibrominated ethoxymagnolol at 1h resulted in deformation (rounding from shoe sole) of most of the larvae of the ichthyophthirius multifiliis and concomitant loss of locomotor ability. Although some of the larvae of Cucumis sativus were rounded at 1h at concentrations of 0.20 and 0.30mg/L of dibromoxyethoxyphyllophol, they were still free to swim, only slightly slower than the rate of movement of the larvae of Cucumis sativus in the control group (0 mg/L).

TABLE 3 Effect of Bibromoethoxymagnolol on Pectinatus Cucumidis larvae killing

2.2 Effect of Bibromoethoxymagnolol on Pectinatus Cucumidis cyst

The effect of varying concentrations of dibromoxyethoxyphenkol on ichthyophthirius multifiliis encystment is shown in table 4. The results show that: the dibromoethoxyphenoxy magnolol of more than 0.6mg/L can obviously influence the cyst formation rate of the ichthyophthirius multifiliis cyst (P is less than 0.05). The concentration of the dibromoethoxyphenoxy magnolol is 0.6mg/L or more, which can cause the hatching rate of the ichthyophthirius multifiliis cysts to be 0.

TABLE 4 Effect of Bibromoethoxymagnolol on Pectinatus Cucumidis cyst

Note: the letters in the table are different and represent statistical differences; cyst formation rate 1-cyst mortality;

hatchability equals reproduction rate.

Pharmacodynamic test of (tetra) Bibromoethoxy magnolol (killing parasitic protozoa of fish)

1 materials and methods

1.1 test animals

The test animal is goldfish (Carassius auratus) with the same specification and source (III).

1.2 parasites

The sources, passages and counting modes of the ichthyophthirius multifiliis the same as those of the ichthyophthirius multifiliis.

1.3 test drugs

The purity of the dibromoethoxy magnolol used in the test is 99.0 percent, and the dibromoethoxy magnolol is prepared by an aquatic animal disease laboratory of northwest agriculture and forestry science and technology university. The dibromine ethoxy magnolol is fully dissolved by dimethyl sulfoxide (DMSO, purchased from Simian chemical reagent factory), the volume is determined in a 100mL volumetric flask, and a dibromine ethoxy magnolol mother liquor with the concentration of 10mg/mL is prepared and stored in a refrigerator at 4 ℃ for later use.

1.4 anti-infective Effect of Bibromoethoxy magnolol

The larvae of the ichthyophthirius multifiliis (20000 larvae/fish) and 50 goldfish were placed in 5 beakers of 2L (10 fish/cup) containing 1000mL of aerated tap water, respectively. After 30 minutes, the goldfish was transferred to a 20L water tank (10 fish/tank, water temperature 21.5 ± 1.5 ℃, bisbromoethoxy magnolol solution was formed by adding the above mother liquor to the water tank) with bisbromoethoxy magnolol concentrations of 0.2, 0.5, 0.8 and 1.2 mg/L. All water tanks were oxygenated with an oxygenating pump and the drug solution was refreshed daily and the test fish were kept in these tanks for at least one week prior to the test. The fish were observed and recorded for mortality each day and the trophozoites of the ichthyophthirius were counted under a dissecting scope on the third day after infection. The whole experiment was repeated 3 times.

1.5 therapeutic Effect of Bibromoethoxymagnolol

20 diseased goldfishes (the number of parasitic ichthyophthirius multiformis of 103 +/-23) and 20 healthy goldfishes are put into four water tanks containing 18L of aerated tap water respectively and are mixed and cultured. And immediately adding the mother liquor of the dibromine ethoxy magnolol into a water tank after polyculture to ensure that the final concentration of the dibromine ethoxy magnolol in the water tank is 0, 0.6, 1.2 and 2.4 mg/L. The liquid medicine with the same concentration is renewed 1 time every three days. The fish deaths were observed and recorded daily and the trophozoites of the ichthyophthirius were counted under a dissecting scope on day 10 after drug treatment. The whole experiment was repeated 2 times.

1.6 oral Pest-resistant Effect of Bibromoethoxy magnolol

Mixing the dibromoethoxy magnolol with common feed, stirring uniformly, and air drying for later use. An oral group and a control group are set, 6 diseased goldfishes and 14 healthy goldfishes are respectively placed in each group, the oral group is fed with feed containing dibrominated ethoxy magnolol with the weight of 1% of the weight of the goldfishes three times a day, and the control group is fed with common feed with the same quality and is continuously fed for 14 days. During the test period, the death conditions of goldfish in each group are counted daily, the protection rate (the mortality rate of the control group-the mortality rate of the treatment group) is calculated by taking the control group as a reference, and the SPSS software is used for carrying out significance analysis to comprehensively evaluate the control effect of oral bisbromoethoxy magnolol on the ichthyophthiriasis.

2 results and analysis

2.1 anti-infective Effect of Bibromoethoxy magnolol

The anti-ichthyophthiriasis effect of bisbromoethoxymagnolol is shown in table 5. The results show that: when the concentration of the dibromoethoxy magnolol is higher than 0.5mg/L, the quantity of the ichthyophthirius multifiliis trophozoites parasitized on the fins of the goldfish after three days of infection can be obviously reduced compared with a control group (0mg/L), so that the infection rate is obviously reduced. This indicates that the bisbromoethoxymagnolol has an obvious effect on inhibiting the epidemic of ichthyophthiriasis.

TABLE 5 Bibromoethoxy magnolol anti-Pediculus Cucumidis Sativi infection effect

2.2 therapeutic Effect of Bibromoethoxymagnolol

The effect of the bisbromoethoxymagnolol on treating ichthyophthiriasis is shown in table 6, and the results show that: when the concentration of the dibromoethoxy magnolol is more than 1.2mg/L, the death rate of the diseased goldfish can be obviously reduced, and the healthy goldfish can be effectively protected from being infected by ichthyophthirius multifiliis; and when the concentration of the dibromoethoxy magnolol is 2.4mg/L, the death rate of the diseased goldfish is further reduced to 30 percent after 10 days.

TABLE 6 Effect of bisbromoethoxymagnolol on treatment of Cucumaria disease

Note: group A refers to diseased goldfish before polyculture; group B was healthy goldfish before polyculture.

2.3 oral Pest-resistant Effect of Bibromoethoxy magnolol

The dibromine ethoxy magnolol is fed with a mixed feed according to a dosage of 10-30 mg/kg (the weight of 1kg of fish is 10-30 mg of dibromine ethoxy magnolol), and the result shows that (table 7): after the continuous feeding for 14 days, the infection rate of the ichthyophthirius multifiliis (diseased goldfish/all goldfishes) in the oral administration 30mg/kg dose group is obviously lower than that in the control group. This shows that feeding the feed containing the dibromine ethoxy magnolol can effectively prevent and treat ichthyophthiriasis of the fishes.

TABLE 7 Effect of oral dibromoethoxyphenol on the prevention and treatment of ichthyophthiriasis

According to the test result of the example 1, the halogen-containing functional group derivative (the dibrominated ethoxy magnolol) has good popularization value as the pesticide effect component of the pesticide and fishing medicine by combining the safe concentration of the dibrominated ethoxy magnolol on the zebra fish and the effective pesticide dose of 0.157(0.130-0.188) mg/L.

Example 2

This example provides a chemically synthesized magnolol derivative, namely dichloroethoxy magnolol. Compared with magnolol, the magnolol derivative has good insect-resistant effect and a relatively simple synthesis process. The concrete description is as follows.

(mono) dichloroethoxy magnolol (C)₂₂H₁₆O₂Cl₂) Preparation of

1 materials and methods

1.1 materials

1.1.1 test samples

Magnolol (98%, HPLC) and tetrabutylammonium bromide (99%, HPLC) used in the tests were purchased from Shanghai Allantin Biotech Co., Ltd. Anhydrous sodium sulfate (99%, HPLC), sodium hydroxide (99%, HPLC), petroleum ether (99%, HPLC), dichloromethane (99%, HPLC), 1-chloropropane (99%, HPLC) were purchased from sienna san pu chemical reagent factory.

1.1.2 test apparatus

ALC-1100 hundredth electronic balance, beijing sidoris instruments systems ltd; KQ-500E type ultrasonic cleaner; 5-10 muL, 20-200 muL pipettor VoluMate; an RE-2000B rotary evaporator of a Yangrong biochemical instrument; its linbel QL-901 vortex oscillator; german Bruker-AM500 NMR spectrometer.

1.2 test methods

1.2.1 Synthesis, separation and purification of Dichloroethoxy magnolol

Referring to fig. 1, 1.07g of magnolol is dissolved in 10mL of NaOH solution with the mass fraction of 10%, 5 equivalents (5 times of the amount of the substance) of 1-chloropropane is added into the obtained magnolol solution, 0.10mg of tetrabutylammonium bromide is added to be used as a catalyst, the mixture is stirred and uniformly mixed at room temperature and then is refluxed at 80 ℃ for 24 hours, after the reaction is finished, a proper amount of dichloromethane is added for extraction for three times, and the lower organic phase is combined; and adding 10-20 g of anhydrous sodium sulfate into the obtained organic phase, standing, drying overnight, filtering to remove sodium sulfate solids, and then removing the reaction solvent by evaporation under reduced pressure (70 ℃, and negative pressure of 0.07 MPa) to obtain a crude product. And (3) carrying out dry loading, separating and purifying all crude products by silica gel column chromatography (petroleum ether: dichloromethane is 1:1, v/v), detecting by TLC, collecting eluted parts containing the target compounds, and evaporating the solvent to obtain a dark brown solid product.

1.2.2 structural identification of Chloroethoxy magnolol

And analyzing and identifying the products synthesized, separated and purified by the method through nuclear magnetic resonance to obtain a C spectrum and an H spectrum.

2 results and analysis

The product spectral data obtained by analysis are as follows:

¹H NMR(500MHz,CDCl₃)δ7.15(d,J＝1.8Hz,2H),7.11(dd,J＝8.4,1.8Hz,2H),6.89(d,J＝8.3Hz,2H),6.02–5.92(m,2H),5.08(dd,J＝22.0,5.2Hz,4H),4.14(t,J＝6.1Hz,4H),3.63(t,J＝6.1Hz,4H),3.37(d,J＝6.6Hz,4H).¹³C NMR(126MHz,CDCl₃)δ154.11,137.89,132.90,132.38,128.62,128.18,115.72,113.38,69.18,42.05,39.55.

the data show that the dichloroethoxy magnolol (the compound with the structure shown in the formula I-2) can be successfully synthesized by adopting the halogenation reaction

The above results show that when the bis-chloroethoxy magnolol in example 2 is synthesized, only 1-bromopropane needs to be replaced by 1-chloropropane, and the synthesis and separation processes and parameters can refer to the preparation method of the bis-chloroethoxy magnolol in example 1.

Example 3

Referring to the preparation method of the bisbromoethoxy magnolol in the example 1, the compound shown in the structural formula I-3 is finally synthesized by replacing 1-bromopropane.

Example 4

When the magnolol derivative of example 1 is synthesized, it is found that the product of different batches of tests may also contain a magnolol derivative in which two hydroxyl groups (hydrogen atoms) are monosubstituted, and the specific structure is shown as formula I-4:

comparative example

The structure of magnolol derivatives has been reported in part (Yang et al, 2015) as follows:

the results of comparing the activity against ichthyophthirius multifiliis and the toxicity against zebra fish of the above examples and comparative examples are shown in table 8.

TABLE 8 comparison of the activity and toxicity of the magnolol derivatives synthesized in accordance with the present invention with those reported

Note: the experimental observation result shows that the toxicity is lower than that of the dibromoethoxy magnolol

As shown in table 8, the magnolol derivative containing a halogen group prepared in the examples of the present invention has an approximately 10-100-fold improved killing effect against chaulmoogra compared to the reported magnolol derivative (Yang et al, 2015) (although the killing effect of the magnolol derivative in which two hydroxyl groups are monosubstituted is much higher than that of magnolol, the effect is improved only by a limited amount compared to the reported magnolol derivative). Therefore, magnolol derivatives (including dibromoxyethoxyphenol) in which both hydroxyl groups are disubstituted have the potential to be preferentially developed as a drug for preventing and treating protozoal diseases in fish.

Claims (10)

1. A magnolol derivative is characterized in that: the derivative is a compound with a structure shown in a formula I or a pharmaceutically acceptable salt, tautomer or stereoisomer of the compound:

wherein R is₁Is H, CH₂Br、CH₂Cl、(CH₂)₂Br or (CH)₂)₂Cl；R₂Is CH₂Br、CH₂Cl、(CH₂)₂Br or (CH)₂)₂Cl。

2. The method of preparing a magnolol derivative according to claim 1, characterized in that: the method comprises the following steps:

halogenating magnolol and halogenated hydrocarbon under alkaline condition to obtain hydrogen atom of single hydroxyl for substitution or hydrogen atoms of two hydroxyl groupsMagnolol derivatives substituted when present, the halogenated hydrocarbon being CH₃(CH₂)_nX, wherein n is 1, 2, X is Br, Cl.

3. The method of preparing magnolol derivatives according to claim 2, characterized in that: the reaction temperature is 80-100 ℃, and the reaction time is 12-24 h; the molar ratio of magnolol to halogenated hydrocarbon is 1: 5-1: 10.

4. The method of preparing magnolol derivatives according to claim 2, characterized in that: the alkaline reagent adopted in the reaction is NaOH or KOH; the reaction uses catalyst which is halogenating agent.

5. Use of magnolol derivatives according to claim 1 for killing ectoparasites.

6. Use according to claim 5, characterized in that: the magnolol derivative is used for killing fish parasitic protozoa.

7. Use according to claim 6, characterized in that: the parasitic protozoa are selected from the group consisting of the Torulopsis multifida.

8. Use of magnolol derivatives according to claim 1 for the preparation of a medicament for the control of parasitic diseases.

9. Use according to claim 8, characterized in that: the parasitic disease includes parasitic protozoal disease.

10. Use according to claim 8, characterized in that: the medicine is externally applied or orally taken.

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