A natural molecular probe derivative, its preparation and application, and a method for measuring the viscosity of fish oil

Abstract

The present invention provides a natural molecular probe derivative, its preparation and application, and a method for measuring the viscosity of fish oil, belonging to the technical field of health product detection. The natural molecular probe derivative provided by the present invention contains multiple freely rotatable single-double bond conjugated structures. Such conjugated structures exhibit a certain flexibility and can rotate freely in fish oil with low viscosity, mainly dissipating the excited state energy through non-radiative transitions, and the intensity of the apparent optical signal release is weak or even absent; in fish oil with high viscosity, the rotation is inhibited, and the excited state energy is mainly dissipated through radiative transitions, and the intensity of the apparent optical signal release is strong. Therefore, the thickness of fish oil can be judged according to the intensity of the optical signal release.

Description

Technical Field

[0001] The invention relates to the technical field of health product detection, and in particular to a natural molecular probe derivative and its preparation and application, and a method for measuring fish oil viscosity. Background Art

[0002] With people's continuous pursuit of quality of life and consideration of life and health, fish oil is one of the must-have consumption for many families in modern society. Among various health products, oral deep-sea fish oil is a kind of nutrient extracted from deep-sea fish. This kind of food is rich in various unsaturated fat components such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Under normal circumstances, terrestrial or freshwater fish almost do not contain EPA and DHA, and the overall unsaturated fatty acid content is also low, so it has to be extracted and supplemented from deep-sea fish. In fact, deep-sea fish oil has a good function of softening blood vessels and reducing triglycerides, and can even activate retinal cells, activate brain cells, and promote the development of brain nerve cells and motor nerves. Therefore, this type of health care product has become one of the star products of health care products on the market, and is deeply loved by teenagers and people with high work pressure.

[0003] High-quality fish oil is light yellow, crystal clear, free of impurities, turbidity and oil leakage, soft and easy to swallow. It is wrapped by a layer of capsule shell to prevent the internal fish oil essence from becoming ineffective under the action of gastric acid. The internal fish oil has good fluidity, and the quality of fluidity is closely related to the type of fish oil. Generally, deep-sea fish oil contains a variety of components, including not only various nutrients, animal extracts, etc., but also some glycerol (propylene glycol), water and plant extracts. Glycerol can provide different wetting and thickening effects for fish oil. These properties ultimately lead to the design of product types and the segmentation of consumer groups. For example: when taking low-viscosity deep-sea fish oil, it appears to have better fluidity, it is easier to flow in the digestive tract, and it is more friendly to those with poor gastrointestinal digestion function; when taking high-viscosity deep-sea fish oil, it shows a certain poor fluidity as a whole, but it is easier to stay in the digestive tract. Although it has high requirements for gastrointestinal digestion function, it is easier to exert its effectiveness for a long time and has better nutritional supply. Therefore, the control of viscosity is crucial to the development of fish oil, which is closely related to the final ingestion effect. Micro-region viscosity is defined as a physical property that can reflect the resistance of a fluid to deformation or prevent the relative flow of adjacent fluid layers. Changes in fish oil micro-region viscosity often occur in the microscopic area, which is difficult to accurately measure at the macroscopic level.

[0004] At present, traditional viscosity measurements mostly rely on various viscometers (falling ball viscometers, rotational viscometers, vibrating viscometers, etc.). These viscometers are relatively effective for macroscopic viscosity measurements. Macroscopic viscosity has a strong dependence on various viscometer devices during measurement and requires a relatively large amount of samples to meet the measurement requirements. However, when measuring the viscosity change in a micro-region, it becomes inadequate and there are also large errors in perceiving the viscosity change in the micro-region, making it difficult to measure the micro-region viscosity at the molecular level. On the other hand, most of the existing functional molecules for viscosity measurement rely on artificial organic synthesis, which not only depends on complex preparation conditions and long preparation processes but also consumes a large amount of organic reagents, and does not conform to the current concept of green, low-carbon, environmental protection, and sustainable development. Based on this, there is an urgent need to develop a natural product-based molecular tool that can be applied to the measurement of the micro-region viscosity of fish oil. Summary of the Invention

[0005] The purpose of the present invention is to provide a natural molecular probe derivative and its preparation, application, and method for measuring the viscosity of fish oil. The natural molecular probe derivative can achieve rapid, efficient, and visual measurement of the micro-region consistency of fish oil.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a natural molecular probe derivative having the structure shown in Formula I:

[0008]

[0009] The present invention provides a preparation method of the natural molecular probe derivative according to the above technical solution, including the following steps:

[0010] Mix syringaldehyde, benzothiazole derivative, metal inorganic salt, and organic solvent, and carry out a dehydration condensation reaction to obtain a natural molecular probe derivative having the structure shown in Formula I;

[0011] The benzothiazole derivative has the structure shown in Formula II:

[0012]

[0013] Preferably, the molar ratio of syringaldehyde to benzothiazole derivative is 1 - 60:1; the molar ratio of metal inorganic salt to benzothiazole derivative is 1 - 250:1.

[0014] Preferably, the metal inorganic salt includes one of sodium carbonate, sodium bicarbonate, cesium carbonate, potassium bicarbonate, calcium hydroxide, potassium carbonate, calcium carbonate, tin acetate, magnesium hydroxide and calcium acetate; the organic solvent includes one or more of N,N-dimethylformamide, ethyl acetate, tetrahydrofuran, ethanol, butanediol, n-butanol, isopropanol, cyclohexanol, 2-ethyl-1-propanol, 2-methyl-2-propanol, 1,3-propanediol, 1,2-propanediol, dimethyl sulfoxide and methanol.

[0015] Preferably, the temperature of the dehydration condensation reaction is 20-100 °C and the time is 1-72 h.

[0016] The present invention provides the application of the natural molecular probe derivative described in the above technical solution or the natural molecular probe derivative prepared by the preparation method described in the above technical solution in measuring the viscosity of fish oil.

[0017] The present invention provides a method for measuring the viscosity of fish oil, comprising the following steps:

[0018] Mix the natural molecular probe derivative with a dissolving reagent, and mix the obtained mixture with fish oil to obtain a test mixed solution; the natural molecular probe derivative is the natural molecular probe derivative described in the above technical solution or the natural molecular probe derivative prepared by the preparation method described in the above technical solution;

[0019] Use a spectrometer to measure the optical signal intensity of the test mixed solution, and judge the viscosity of the fish oil according to the corresponding relationship between the optical signal intensity and the viscosity.

[0020] Preferably, the excitation wavelength used for the measurement is 380-420 nm, and the recording range of the emission spectrum is 430-780 nm.

[0021] Preferably, the concentration of the natural molecular probe derivative in the dissolving reagent is 1-10 mol / L; the concentration of the natural molecular probe derivative in the test mixed solution is 10 μmol / L.

[0022] Preferably, when the optical signal intensity > 400, it is determined as high-viscosity fish oil; when the optical signal intensity < 300, it is determined as low-viscosity fish oil.

[0023] The natural molecular probe derivatives provided by the present invention contain a large conjugated structure with freely rotatable single and double bonds. Such conjugated structures can mechanically rotate freely in fish oil with a low viscosity. The excited state energy obtained by an external excitation light source can be dissipated through mechanical motion, and the intensity of the finally released optical signal is weak. By the apparent signal intensity, it can be judged that the fish oil is thinner, with better fluidity and digestion effects, and also better infiltration effects in the digestive tract. As the consistency of the fish oil gradually increases, the mechanical rotation of the natural molecular probe in the fish oil is gradually inhibited, and the excited state energy obtained by the external excitation light source is gradually dissipated through radiative transition, and the presented optical signal intensity gradually increases. The optical signal intensity will gradually increase as the consistency of the fish oil gradually rises, thus achieving a "turn-on" visual imaging effect. Therefore, such molecular probes can be used as tools for the consistency blending process of fish oil, and the results of its blending can be visually monitored through the intensity of the released optical signal. This method is very beneficial for controlling the final fluidity, digestion and infiltration effects of fish oil. Fish oil with a higher consistency is more suitable for people with better digestive functions, and its internal solution concentration is greater, while fish oil with a lower consistency is more suitable for people with poor digestive functions. In particular, the relative amount of omega-3 unsaturated fatty acids contained may cause changes in the consistency of fish oil.

[0024] The natural molecular probe derivatives of the present invention can emit strong fluorescence signals in the range of 420 - 780 nm under the irradiation of an external excitation light of 360 - 450 nm, and the wavelength corresponding to the maximum emission peak is 510 nm. It can visually measure the consistency of fish oil, thereby indirectly judging its thinness and thickness, providing data reference for the development of the consistency blending process of health products such as fish oil, and helping to accurately regulate its thinness and thickness to meet the needs of different populations.

[0025] The natural molecular probe derivative of the present invention is 2-(benzothiazol-2-yl)-3-(4-hydroxy-3,5-dimethoxyphenyl)acrylonitrile (BHDPA), and its molecular formula is C 18 H 14N2O3S, with a relative molecular mass of 338.07251, is a molecular probe obtained by further modification of natural plant product syringaldehyde. It is a pale yellow (off-white) powder, soluble in various common solvents such as ethyl acetate, methanol, ethanol, N,N-dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, etc. This molecular probe derivative has a conjugated structure, good photostability, stable chemical structure, suitable for long-term storage, extremely low hygroscopicity, and is not prone to deliquescence and deterioration. There is a freely rotatable conjugated structure in its molecular structure, presenting a certain flexible conjugated structure. The conjugated structure can rotate freely in fish oil with low consistency (low viscosity), but it is difficult to rotate in fish oil with high consistency (high viscosity). The mechanical state limitation is converted into the strength of the optical signal for release, making the change in the overall consistency visible, providing real-time, non-destructive, and visual detection support for the process development of fish oil. And it will not be affected by common food additives and the main components in various fish oils (such as eicosapentaenoic acid, docosahexaenoic acid, etc.), which are common brain-boosting and lipid-lowering components in fish oil, on the release of its optical signal ( Figure 2 ), so it is particularly suitable for the consistency determination of fish oil.

[0026] The results of the examples show that the emission peak wavelength of the natural molecular probe derivative provided by the present invention reaches 510 nm, is not easily affected by various nutrient components and food additives inside fish oil, and the logarithmic function of the optical signal intensity released and the fish oil consistency value is in agreement with the relationship function, and the viscosity sensitivity coefficient reaches 0.73, indicating that its sensitivity to consistency is very high and it is very suitable for measuring the consistency of fish oil; in the photostability test experiment, the natural molecular probe derivative provided by the present invention can maintain good photostability in solutions with high and low consistency; at the same time, the absorbance of the natural molecular probe derivative changes little in various solutions with different polarities, and the main absorption spectral peak is also concentrated around 400 nm, indicating that it can be used in solution atmospheres with various polarities; in addition, this natural molecular rotor can show good signal release intensity within the common pH range (pH = 2 - 12).

[0027] In summary, compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] (1) The natural molecular probe derivative provided by the present invention is obtained by chemical modification of natural product syringaldehyde and is prepared by a one-step method. The required raw materials are rich in sources and are natural plant extracts, with low prices. The overall application preparation cost is low, and the whole process does not require complex preparation processes, is suitable for large-scale chemical preparation, has a high yield, and the process is relatively green and environmentally friendly, meeting the current concept of low-carbon sustainable development;

[0029] (2) The natural molecular probe derivatives provided by the present invention can visualize and image fish oils with different consistencies, and can be used for the formulation and control of the consistency process of fish oils, which is beneficial to the preparation of various products that meet the requirements of different fish oil cleaning effects;

[0030] (3) The natural molecular probe derivatives provided by the present invention have stable chemical properties, good photostability, and a wide pH application range. They can still stably exist in complex fish oils, the released optical signals are not easily interfered, they have high sensitivity to consistency, are not easily interfered by other nutritional components and food additives in fish oils, and can maintain good optical signal release effects in various polarities. Brief Description of the Drawings

[0031] Figure 1 It is a schematic diagram of the mechanism for detecting the consistency of deep-sea fish oil by the natural molecular probe derivatives provided by the present invention;

[0032] Figure 2 It is a bar chart of the selective test light intensity of the natural molecular probe derivatives in Example 1;

[0033] Figure 3 It is a mass spectrum of the natural molecular probe derivatives in Example 1;

[0034] Figure 4 It is an emission spectrum of the natural molecular probe derivatives in different volume fractions of glycerol / water mixed solutions in Example 1;

[0035] Figure 5 It is a logarithmic function of the fluorescence intensity and consistency value of the natural molecular probe derivatives in Example 1;

[0036] Figure 6 It is a photostability test chart of the natural molecular probe derivatives in high-consistency and low-consistency solutions respectively in Example 1;

[0037] Figure 7 It is an absorption spectrum of the natural molecular probe derivatives in different polar solutions in Example 1;

[0038] Figure 8 It is an emission spectrum of the natural molecular probe derivatives in different pH solutions in Example 1;

[0039] Figure 9 It is an emission spectrum of the natural molecular probe derivatives in different commercially available deep-sea fish oils in Example 1.

[0040] Figure 10 It is a chart of the apparent optical signal release of the natural molecular probe derivatives in different fish oils in Example 1. Detailed Embodiments

[0041] The present invention provides a natural molecular probe derivative having the structure shown in Formula I:

[0042]

[0043] The natural molecular probe derivative provided by the present invention has the structure shown in Formula I, which contains multiple freely rotatable single-double bond conjugated structures. Such conjugated structures exhibit a certain flexibility and can rotate freely in low-viscosity fish oil, mainly dissipating the excited state energy through non-radiative transition, and the intensity of the apparent optical signal release is weak or even non-existent; in high-viscosity fish oil, the rotation is inhibited, and the excited state energy is mainly dissipated through radiative transition, and the intensity of the apparent optical signal release is strong. Therefore, the thickness of fish oil can be judged according to the intensity of the optical signal release. The mechanism of the natural molecular probe derivative of the present invention for measuring the viscosity of fish oil is shown in detail in Figure 1 .

[0044] In addition, the chemical structure of the natural molecular probe derivative of the present invention is stable, and the photostability is also better. It can exert its efficacy within a common pH range, and the absorbance is similar in various polar solution atmospheres, and even maintains a good optical signal intensity under long-term irradiation.

[0045] The present invention provides a preparation method of the natural molecular probe derivative described in the above technical solution, including the following steps:

[0046] Mix syringaldehyde, benzothiazole derivative, metal inorganic salt and organic solvent, and carry out a dehydration condensation reaction to obtain a natural molecular probe derivative having the structure shown in Formula I;

[0047] The benzothiazole derivative has the structure shown in Formula II:

[0048]

[0049] In the present invention, unless otherwise specified, the required preparation raw materials are all commercially available products well-known to those skilled in the art.

[0050] In the present invention, the molar ratio of syringaldehyde to benzothiazole derivative is preferably 1-60:1, more preferably 20-50:1, and even more preferably 30-40:1.

[0051] In the present invention, the syringaldehyde has the structure shown in Formula 1:

[0052]

[0053] In the present invention, the benzothiazole derivative is a commercially available product and is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0054] In the present invention, the molar ratio of the metal inorganic salt to the benzothiazole derivative is preferably 1 to 250:1, more preferably 2 to 120:1, and further preferably 4 to 80:1.

[0055] In the present invention, the metal inorganic salt preferably includes one of sodium carbonate, sodium bicarbonate, cesium carbonate, potassium bicarbonate, calcium hydroxide, potassium carbonate, calcium carbonate, tin acetate, magnesium hydroxide, and calcium acetate; the metal inorganic salt is more preferably a nanoscale inorganic salt. The present invention utilizes the metal inorganic salt to effectively remove the water generated during the reaction and promote the reaction to proceed to the right.

[0056] In the present invention, the organic solvent preferably includes one or more of N,N-dimethylformamide, ethyl acetate, tetrahydrofuran, ethanol, butanediol, n-butanol, isopropanol, cyclohexanol, 2-ethyl-1-propanol, 2-methyl-2-propanol, 1,3-propanediol, 1,2-propanediol, dimethyl sulfoxide, and methanol, and more preferably one or more of tetrahydrofuran, N,N-dimethylformamide, ethyl acetate, ethanol, dimethyl sulfoxide, and methanol; when there are two or more of the above organic solvents, the ratio of different types of organic solvents is preferably an equal volume ratio.

[0057] In the present invention, the process of mixing syringaldehyde, benzothiazole derivative, metal inorganic salt, and organic solvent preferably comprises dissolving syringaldehyde in an organic solvent to obtain a syringaldehyde solution; dissolving the benzothiazole derivative in an organic solvent to obtain a benzothiazole derivative solution; dispersing the metal inorganic salt in an organic solvent to obtain a metal inorganic salt dispersion; dropping the metal inorganic salt dispersion into the benzothiazole derivative solution, stirring and mixing at room temperature for 1 to 32 h, more preferably 15 to 25 h, controlling the stirring rate to be 100 to 1500 rpm, more preferably 500 to 900 rpm, and mixing the obtained mixture with the syringaldehyde solution; the dropping rate is preferably 1 drop / s to 8 drops / s, more preferably 3 drops / s to 5 drops / s.

[0058] In the present invention, the molar concentration of the syringaldehyde solution is preferably 1 to 400 mol / L, more preferably 5 to 150 mol / L, and further preferably 15 to 120 mol / L; the molar concentration of the benzothiazole derivative solution is preferably 1 to 50 mol / L, more preferably 2 to 40 mol / L, and further preferably 3 to 30 mol / L; the molar concentration of the metal inorganic salt dispersion is preferably 1 to 200 mol / L, more preferably 100 mol / L.

[0059] In the present invention, the dehydration condensation reaction is a Knoevenagel dehydration condensation reaction; the temperature of the dehydration condensation reaction is preferably 20-100 °C, more preferably 25-68 °C, the time is preferably 1-72 h, more preferably 24-56 h, and further preferably 10-50 h.

[0060] In the present invention, the dehydration condensation reaction is preferably carried out under the protection of an inert gas to avoid oxidation of some active groups; the inert gas is preferably one of helium, argon, neon and krypton.

[0061] In the present invention, the equation of the Knoevenagel dehydration condensation reaction is as follows:

[0062]

[0063] After completing the dehydration condensation reaction, the present invention preferably purifies the obtained product to obtain a natural molecular probe derivative having the structure shown in Formula I. In the present invention, the purification preferably includes distillation, extraction, chromatography and drying in sequence. In the present invention, the distillation is preferably carried out by a rotary evaporator under a low pressure state of -0.09 MPa to -0.08 MPa to remove the reaction solvent; the extraction agent used for extraction is preferably a mixed system of ethyl acetate and deionized water, and the volume ratio of ethyl acetate to deionized water is preferably 1-12:1, more preferably 1-10:1, and even more preferably 1-8:1; after the extraction, the present invention preferably dries with anhydrous Na2SO4 after removing the extraction agent; the chromatography is preferably carried out using a silica gel chromatographic plate to purify the obtained crude product, and the purification is preferably carried out in a methanol / ethyl acetate mixed system, and the volume ratio of methanol to ethyl acetate is preferably 1:1-15, more preferably 1:5-12; the drying method is preferably freeze-drying, and the freeze-drying preferably includes dissolving the fine product obtained by chromatography in deionized water to make the solid content 1-60 mg / mL, more preferably 30-60 mg / mL, and then placing it in a freeze-dryer and standing for 1-72 h, more preferably 40 h, and the temperature of the freeze-drying is preferably -70 to -5 °C, more preferably -40 °C.

[0064] The present invention provides the use of the natural molecular probe derivative described in the above technical solution or the natural molecular probe derivative prepared by the preparation method described in the above technical solution in measuring the viscosity of fish oil.

[0065] The present invention provides a method for measuring the viscosity of fish oil, comprising the following steps:

[0066] Mix the natural molecular probe derivative with a dissolution reagent, and then mix the resulting mixture with fish oil to obtain a test mixture solution; the natural molecular probe derivative is the natural molecular probe derivative described in the above technical solution or the natural molecular probe derivative prepared by the preparation method described in the above technical solution;

[0067] Measure the optical signal intensity of the test mixture solution using a spectrometer, and judge the viscosity of the fish oil according to the corresponding relationship between the optical signal intensity and the viscosity.

[0068] In the present invention, the dissolution reagent is preferably n-butanol; the concentration of the natural molecular probe derivative in the dissolution reagent is preferably 1-10 mol / L; the concentration of the natural molecular probe derivative in the test mixture solution is preferably 10 μmol / L.

[0069] In the present invention, the excitation wavelength used for the measurement is preferably 380-420 nm, more preferably 390-410 nm, and further preferably 400 nm; the recording range corresponding to the emission spectrum is preferably 430-780 nm.

[0070] In the present invention, when the optical signal intensity > 400, it is determined as high-viscosity fish oil; when the optical signal intensity < 300, it is determined as low-viscosity fish oil.

[0071] During the measurement process, as the viscosity of the system increases, the released optical signal intensity will gradually increase, achieving a "turn-on" visual detection effect. The flexible conjugated molecular structure of this molecular probe can exhibit different rotational characteristics in solution atmospheres with different viscosities, resulting in significant differences in the excited-state dissipation mode, and thus significant differences in the optical signal intensity. This is a typical change in the photoluminescence mode caused by the change in micro-region viscosity (consistency). By detecting the optical signal intensity, the viscosity of the fish oil can be indirectly judged, which can provide great help for the process control during its preparation.

[0072] The technical solutions provided by the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0073] Example 1

[0074] Dissolve 2740.5 mg of syringaldehyde in ethanol and stir evenly to obtain a syringaldehyde solution with a concentration of 15 M;

[0075] Dissolve 348.4 mg of benzothiazole derivative in ethanol and stir ultrasonically to obtain a benzothiazole derivative solution with a concentration of 2 M;

[0076] Disperse 1.38 g of nanoscale potassium carbonate in ethanol, control its concentration to be 100 mol / L, add the obtained dispersion to the benzothiazole derivative solution at a dropping rate of 3 drops / s, mix at room temperature for 15 h, control the stirring rate to be 900 rpm, mix the obtained mixed solution with the syringaldehyde solution, fill with helium for protection, and maintain throughout the reaction process. Control the temperature of the Knoevenagel dehydration condensation reaction to be 68 °C and the reaction duration to be 24 h;

[0077] After the reaction is completed, carry out vacuum distillation of the obtained product under a low pressure of -0.09 MPa using a rotary evaporator; extract the above product with a mixed system of ethyl acetate and deionized water. When extracting, the volume ratio of ethyl acetate to deionized water is 8:1. After removing the extractant, dry it with anhydrous Na2SO4; then purify the obtained crude product on a silica gel chromatographic plate in a mixed system of methanol / ethyl acetate (methanol / ethyl acetate, V / V = 1:5); dissolve the obtained fine product in deionized water to make the solid content 30 mg / mL, place it in a freeze dryer for drying, with a drying duration of 40 h and a drying temperature of -40 °C to obtain 601.8 mg of powder (yield 89%), namely the natural molecular probe derivative, denoted as BHDPA.

[0078] Example 2

[0079] Dissolve 182.2 mg of syringaldehyde in ethyl acetate, stir evenly to obtain a syringaldehyde solution with a concentration of 1 M;

[0080] Dissolve 174.2 mg of benzothiazole derivative in ethyl acetate, stir ultrasonically to obtain a benzothiazole derivative solution with a concentration of 1 M;

[0081] Disperse 84.0 mg of sodium bicarbonate in ethyl acetate, control the concentration of the dispersion to be 1 mol / L, add the obtained dispersion to the benzothiazole derivative solution at a dropping rate of 1 drop / s, mix at room temperature for 1 h, control the stirring rate to be 1500 rpm, mix the obtained mixed solution with the syringaldehyde solution, fill with argon for protection, and maintain throughout the reaction process. Control the temperature of the Knoevenagel dehydration condensation reaction to be 20 °C and the reaction duration to be 72 h;

[0082] After the reaction was completed, the obtained product was subjected to vacuum distillation using a rotary evaporator under a low pressure of -0.09 MPa; the above product was extracted using a mixed system of ethyl acetate and deionized water. During extraction, the volume ratio of ethyl acetate to deionized water was 1:1. After removing the extractant, it was dried with anhydrous Na2SO4; then, the obtained crude product was purified using a silica gel chromatographic plate in a methanol / ethyl acetate mixed system (methanol / ethyl acetate, V / V = 1:1); the obtained fine product was dissolved in deionized water to a solid content of 1 mg / mL and placed in a freeze dryer for drying. The drying time was 72 h and the drying temperature was -5 °C, obtaining 263.7 mg of powder (yield 78%), namely the natural molecular probe derivative, denoted as BHDPA.

[0083] The mass spectrometry results of the natural molecular probe derivative (BHDPA) obtained in this example were the same as those obtained in Example 1.

[0084] Example 3

[0085] Dissolve 273.3 g of syringaldehyde in methanol and stir evenly to obtain a syringaldehyde solution with a concentration of 400 M;

[0086] Dissolve 4.35 g of benzothiazole derivative in methanol and stir ultrasonically to obtain a benzothiazole derivative solution with a concentration of 50 M;

[0087] Disperse 863.8 g of potassium carbonate in methanol, control the concentration of the dispersion to 200 mol / L, and add this dispersion dropwise to the benzothiazole derivative solution at a dropping rate of 8 drops / s. Mix at room temperature for 32 h, control the stirring rate to 100 rpm, mix the obtained mixed solution with the syringaldehyde solution, charge neon for protection, and maintain throughout the reaction process. Control the temperature of the Knoevenagel dehydration condensation reaction to 100 °C and the reaction time to 1 h;

[0088] After the reaction was completed, the obtained product was subjected to vacuum distillation using a rotary evaporator under a low pressure of -0.09 MPa; the above product was extracted using a mixed system of ethyl acetate and deionized water. During extraction, the volume ratio of ethyl acetate to deionized water was 12:1. After removing the extractant, it was dried with anhydrous Na2SO4; then, the obtained crude product was purified using a silica gel chromatographic plate in a methanol / ethyl acetate mixed system (methanol / ethyl acetate, V / V = 1:15); the obtained fine product was dissolved in deionized water to a solid content of 60 mg / mL and placed in a vacuum oven for drying. The drying time was 1 h and the drying temperature was -70 °C, obtaining 6.68 g of powder (yield 79%), namely the natural molecular probe derivative, denoted as BHDPA.

[0089] The mass spectrometry results of the natural molecular probe derivative (BHDPA) obtained in this example are the same as those obtained in Example 1.

[0090] Characterization and performance testing

[0091] Dissolve 16.9 mg of the natural molecular probe derivative (BHDPA) prepared in Example 1 in n-butanol to make its concentration 5.0 mM. Add 90% glycerol and the main components of different fish oil products to the resulting solution to form a test solution. The main components of the fish oil products include metal salt ions (Na + , K + , NO3 - , SO4 2- ), vitamin C, DHA, EPA and some amino acids (Cys, Hcy, GSH). The concentrations of the main components of the fish oil products in the test solution are all 100 μM, and the concentration of BHDPA in the test solution is all 10 μM. Perform corresponding spectroscopic tests and compare with the blank control. The results are shown in Figure 2 ; Figure 2 is the bar chart of the selective test light intensity of the natural molecular probe derivative prepared in Example 1; as can be seen from Figure 2 , the prepared natural molecular probe derivative (BHDPA) can maintain a low light signal release in various main components of fish oil, and only shows an obvious light signal release intensity in the 90% glycerol solution, indicating that the natural molecular probe derivative (BHDPA) has good selectivity and is not easily interfered by other components of fish oil, and is suitable for detecting viscosity in a complex environment.

[0092] Perform high-resolution mass spectrometry detection on the natural molecular probe derivative prepared in Example 1, and the results are as shown in Figure 3 ; as can be seen from Figure 3 , the relative molecular mass of the natural molecular probe derivative prepared in Example 1 is 338.07638 [M] + , and its theoretical relative mass estimated value is 338.07251. It can be determined from the relative molecular mass that the synthesized product is consistent with the relative molecular mass of the natural molecular probe derivative 2-(benzothiazol-2-yl)-3-(4-hydroxy-3,5-dimethoxyphenyl)acrylonitrile (BHDPA). The molecular formula of Formula I is C 18 H 14 N2O3S.

[0093] Test example

[0094] 1. Response test of the natural molecular probe derivative (BHDPA) to viscosity

[0095] Prepare mixed solutions containing glycerol and deionized water with different volume fractions as test solutions, where the volume fraction of glycerol is 0% - 90%. Set the external excitation wavelength to 400 nm, and control the concentration of the natural molecular probe derivative in the test solution to be 10 μM.

[0096] Adjust the viscosity of the mixed solution (1.0 cP - 218.8 cP) by adjusting the volume concentrations of glycerol and deionized water. After storing at room temperature for 0.5 h, conduct the test at room temperature. The specific test results are as Figure 4 shown. It can be found that as the viscosity of the solution gradually increases, the apparent optical signal intensity also gradually increases. In particular, when the volume fraction of glycerol exceeds 70%, the viscosity of the mixed system increases more significantly, and its optical signal intensity increases sharply. Compared with the solution system without added glycerol, it increases by up to 95 times at most.

[0097] In addition, the test finds that the logarithmic function of the optical signal intensity of the mixed solution and the viscosity value of the solution (the specific logarithmic function values are shown in Table 1) can be fitted into a straight line, specifically as Figure 5 shown.

[0098] Table 1 Logarithmic values of viscosity and fluorescence intensity

[0099]

[0100]

[0101] From Figure 5 the data in and Table 1, it can be seen that the natural molecular probe derivative BHDPA provided by the present invention can release a stronger optical signal as the viscosity value increases, which is consistent with the -Hoffmann relationship. It can be seen that the viscosity sensitivity coefficient of BHDPA is 0.73, and the fitting determination coefficient is 0.99.

[0102] The test results show that the natural molecular probe derivative BHDPA provided by the present invention has good detection sensitivity to the micro-region viscosity of the solution and can be used as supporting data for the viscosity (consistency) adjustment process of fish oil.

[0103] 2. Photostability test of natural molecular probe derivative (BHDPA)

[0104] Dissolve 33.8 mg of the natural molecular probe derivative 2-(benzothiazol-2-yl)-3-(4-hydroxy-3,5-dimethoxyphenyl)acrylonitrile (BHDPA) prepared in Example 1 in n-butanol, control its concentration to be 10 mM, and add it to solutions with different viscosities (deionized water (viscosity 1.0 cP) and 90% volume fraction glycerol solution (viscosity 218.8 cP)) respectively, so that the concentration of BHDPA in the test solution is 10 μM. Continuously irradiate it with an excitation light source at 400 nm for 60 min, and test the change rule of its optical signal intensity. The test results are as Figure 6 shown, and the obtained data are shown in Table 2.

[0105] Table 2 Fluorescence test results

[0106]

[0107] From Figure 6 the data obtained in Table 2, it can be seen that the natural molecular probe derivative (BHDPA) has good photostability and can release stable optical signals under the irradiation of an excitation light source for a long time.

[0108] 3. Universality test of the natural molecular probe derivative (BHDPA)

[0109] Dissolve 67.6 mg of the natural molecular probe derivative 2-(benzothiazol-2-yl)-3-(4-hydroxy-3,5-dimethoxyphenyl)acrylonitrile (BHDPA) prepared in Example 1 in n-butanol, control its concentration to be 20 mM, and add it to 6 common solvents with different polarities respectively, so that the concentration of BHDPA in the test solution is 10 μM, and test the change rule of its absorbance. The 6 solutions with different polarities are tetrahydrofuran, glycerol, ethanol, toluene, dichloromethane and dimethyl sulfoxide. The above tests are carried out at room temperature, and the results are as Figure 7 shown.

[0110] From Figure 7 it can be seen that the absorbances in 6 common solvents are similar and there is no significant difference. In addition, except that the peak value of the absorption wavelength of glycerol has a slight red shift, the absorption wavelength changes little in the other 5 common solvents. This may be because in a solution atmosphere with a higher viscosity, its conformation has spatial conjugation, indirectly extending its conjugation degree, indicating that the natural molecular probe derivative (BHDPA) can effectively absorb the energy of the excitation light in a variety of solutions with different polarities, and the absorption spectrum will not change due to the change of solution polarity, indicating that it has good universality in complex fish oil, and the fluctuation of polarity will not affect its measurement effect on viscosity.

[0111] 4. pH stability test of the natural molecular probe derivative (BHDPA)

[0112] Dissolve 16.9 mg of the natural molecular probe derivative 2-(benzothiazol-2-yl)-3-(4-hydroxy-3,5-dimethoxyphenyl)acrylonitrile (BHDPA) prepared in Example 1 in n-butanol, control its concentration to be 5 mM, and add it to PBS buffer solutions with pH = 2 - 12 (2, 5, 6.8, 7.4, 9, and 12) respectively, so that the concentration of BHDPA in the test solution is 10 μM, and test the change rule of its absorbance. The test is carried out at room temperature, and the test results are as Figure 8 shown.

[0113] It can be seen from Figure 8 that the fluorescence intensity of the natural molecular probe derivative (BHDPA) does not change significantly within a relatively wide pH range, and shows good stability of light signal release within this pH range, indicating that this natural molecular rotor can be used in fish oils with various pH atmospheres.

[0114] Application Example 1

[0115] Dissolve 22.5 mg of the natural molecular probe derivative (BHDPA) prepared in Example 1 in n-butanol, control its concentration to be 6.6 mM. At the same time, select 3 commercially available deep-sea fish oils (Deep-sea Fish Oil 1 - Jishengyuan, Deep-sea Fish Oil 2 - Runmeibeijian, Deep-sea Fish Oil 3 - Quankang) as test objects, add the above-mentioned natural molecular probe derivative (BHDPA) to these 3 deep-sea fish oils, so that the concentration of BHDPA in the fish oil mixture is 10 μM, and carry out the test at room temperature. Control the excitation wavelength of the external light source to be 400 nm, and the test results are as Figure 9 shown.

[0116] It can be seen from Figure 9It can be seen that the light signal release intensities of the three kinds of deep-sea fish oils are different, indicating that there are certain viscosity differences among these three kinds of deep-sea fish oils. This may be related to the different micro-region viscosities of the deep-sea fish oils. The different micro-region viscosities of the three kinds of deep-sea fish oils will greatly affect their speeds in the gastric juice digestion area and the degree of nutrient absorption. The deep-sea fish oil with a high viscosity has a slow flow rate in the stomach, a longer digestion and absorption time, and a slower nutrient release degree. The lack of digestive function may further retard the digestion process. Therefore, for people with poor gastrointestinal function, they need deep-sea fish oil with a lower viscosity for digestion more. In contrast, for people with good gastrointestinal function, the deep-sea fish oil with a high viscosity has a longer flow time in the digestive tract, is more durable, and can release nutrients in a long-term manner, which is beneficial for full digestion and will not waste resources. From the final test results, it can be seen that deep-sea fish oil 1 (2.2 cP) belongs to low-viscosity fish oil (1.0 cP - 3.0 cP), presenting a relatively thin apparent effect as a whole, and is more suitable for users with poor gastrointestinal function; deep-sea fish oil 2 (3.3 cP) belongs to medium-viscosity fish oil (3.0 cP - 5.0 cP), with a medium viscosity as a whole; deep-sea fish oil 3 (6.8 cP) belongs to high-viscosity fish oil (>5.0 cP), presenting a lower fluidity as a whole, which is more conducive to long-term slow release.

[0117] Figure 10 It is the apparent light signal release diagram of the natural molecular probe derivative (BHDPA) in three kinds of fish oils in Example 1. The test results show that the natural molecular probe derivative (BHDPA) provided by the present invention can fully sense the changes in the micro-region viscosity in deep-sea fish oil and release it through visual light signals. This is of great significance for studying the thickening and blending processes of different kinds of deep-sea fish oils and can develop more products that meet the needs of different customers.

[0118] As can be seen from the above examples and application examples, the natural molecular probe derivative provided by the present invention, 2-(benzothiazol-2-yl)-3-(4-hydroxy-3,5-dimethoxyphenyl)acrylonitrile (BHDPA), has a flexible conjugated structure and can exhibit different mechanical rotation states in solution environments with different consistencies. The change in the consistency of fish oil can be converted into a visualized light signal and released, providing a brand-new molecular-level tool for effectively detecting the physical index of consistency. Various test results show that the natural molecular probe derivative (BHDPA) can still maintain a relatively stable light release intensity under long-term irradiation, that is, it has good photostability. It can also maintain a good light signal release intensity within a wide pH range (pH = 2 to 12). The absorbance change is small in various polar solutions, indicating that it is very suitable for use in complex liquids containing various nutritional components and food additives. Its emission peak wavelength is 510 nm, which can effectively avoid background light signal interference caused by various components in fish oil. Moreover, the natural molecular probe derivative is prepared by a one-step method. The preparation process is green, environmentally friendly, and has a high yield. The raw materials required are natural plant extracts, which are inexpensive, simple to obtain, and have a low preparation cost. The post-treatment process is simple and easy to operate. Overall, it is low-carbon and environmentally friendly and suitable for industrial application.

[0119] The above description is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A natural molecular probe derivative, characterized in that, It has the structure shown in Formula I: Formula I.

2. The preparation method of the natural molecular probe derivative according to claim 1, characterized in that, It includes the following steps: Mix syringaldehyde, benzothiazole derivative, metal inorganic salt and organic solvent, and carry out a dehydration condensation reaction to obtain a natural molecular probe derivative with the structure shown in Formula I; The benzothiazole derivative has the structure shown in Formula II: Formula II; The molar ratio of syringaldehyde to benzothiazole derivative is 1~60:1; the molar ratio of metal inorganic salt to benzothiazole derivative is 1~250:1; The metal inorganic salt includes one of sodium carbonate, sodium bicarbonate, cesium carbonate, potassium bicarbonate, calcium hydroxide, potassium carbonate, calcium carbonate, tin acetate, magnesium hydroxide and calcium acetate; The temperature of the dehydration condensation reaction is 20~100 °C, and the time is 1~72 h.

3. The preparation method according to claim 2, characterized in that, The organic solvent includes one or several of N,N-dimethylformamide, ethyl acetate, tetrahydrofuran, ethanol, butanediol, n-butanol, isopropanol, cyclohexanol, 2-ethyl-1-propanol, 2-methyl-2-propanol, 1,3-propanediol, 1,2-propanediol, dimethyl sulfoxide and methanol.

4. Use of the natural molecular probe derivative according to claim 1 or the natural molecular probe derivative prepared by the preparation method according to any one of claims 2~3 in measuring the viscosity of fish oil.

5. A method for measuring the viscosity of fish oil, characterized in that, It includes the following steps: Mix the natural molecular probe derivative with a dissolution reagent, and mix the resulting mixture with fish oil to obtain a test mixture solution; the natural molecular probe derivative is the natural molecular probe derivative according to claim 1 or the natural molecular probe derivative prepared by the preparation method according to any one of claims 2~3; Measure the optical signal intensity of the test mixture solution using a spectrometer, and judge the viscosity of the fish oil according to the corresponding relationship between the optical signal intensity and the viscosity; The excitation wavelength used for the measurement is 380~420 nm, and the recording range of the emission spectrum is 430~780 nm; When the optical signal intensity > 400, it is determined as high-viscosity fish oil; when the optical signal intensity < 300, it is determined as low-viscosity fish oil.

6. The method according to claim 5, wherein The concentration of the natural molecular probe derivative in the dissolution reagent is 1~10 mol / L; the concentration of the natural molecular probe derivative in the test mixture solution is 10 μmol / L.

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