Tellurium-containing melanin as well as preparation method and application thereof

Abstract

The invention relates to a compound, in particular to tellurium-containing melanin as well as a preparation method and application thereof. The compound of the formula (I) has excellent oxidation resistance, radiation protection capability and contrast imaging capability. As a novel biological material which is simple to prepare, safe to synthesize, good in biocompatibility and excellent in radiation protection performance, the tellurium-containing melanin is expected to be widely applied to the fields of oral medicines, external dressings, cosmetic auxiliary materials, medical radiation protection articles, nuclear wastewater treatment, gastrointestinal tract radiography and the like; in the formula (I), R1 and R2 are respectively and independently selected from-CH3,-NH2,-COOH, CHO,-C6H5,-OH,-H,-F,-Cl,-Br,-I and-NO2.

Description

Technical Field

[0001] This invention relates to compounds, specifically to a tellurium-containing melanin, its preparation method, and its applications. Background Art

[0002] With the rapid development of the nuclear industry and nuclear medicine, safety issues arising from accidental radiation exposure are receiving increasing attention. There are many sources of ionizing radiation hazards, such as radiotherapy, imaging diagnostics, and the discharge of nuclear wastewater and radioactive wastewater, as well as natural radiation sources such as cosmic rays and radioactive elements. Research on radiation protection is of great significance.

[0003] Melanin is a class of naturally occurring high-molecular polymers widely found in the biological world, such as in black fungus, cuttlefish ink, animal hair, and plant seeds, playing an important role in the stress resistance of microorganisms, plants, and animals. Studies have shown that melanin can help certain microorganisms survive in environments with strong radiation. However, due to its inherently lightweight elemental composition, the radiation protection performance of melanin is limited. Therefore, its radiation protection capabilities need further improvement. Patent CN110279613A invented a light-colored melanin sunscreen for skin protection against ultraviolet rays; the sunscreen is a dopamine-based polymer with low visible light absorption, good biological stability, and significant free radical scavenging effect. CN114316224A reported a method for preparing and applying artificial pustular melanin nanomaterials, using sodium periodate as an oxidant and homogentic acid as a pustular melanin precursor molecule, which are polymerized and assembled to form nanoparticles, thereby obtaining artificial pustular melanin nanomaterials. However, these improved synthesis methods are still based on lightweight elements. By introducing selenium, patent CN118496222A invented a selenium-containing melanin with excellent antioxidant and radiation protection capabilities.

[0004] Tellurium and selenium belong to the same group of elements, with Tellurium having a larger atomic number (Te:52 vs Se:34). Therefore, introducing tellurium into melanin is expected to improve its radiation protection properties by optimizing its chemical structure and increasing the attenuation of radiation energy. Summary of the Invention

[0005] In a first aspect, the present invention provides a compound of formula (I),

[0006]

[0007] R1 and R2 are each independently selected from -CH3, -NH2, -COOH, CHO, -C6H5, -OH, -H, -F, -Cl, -Br, -I, and -NO2.

[0008] Optionally, R1 is -H and R2 is -H, or R1 is -COOH and R2 is -COOH; or R1 is -H and R2 is -COOH; or R1 is -COOH and R2 is -H.

[0009] Optionally, the tellurium heterocycle can be a four-membered ring, five-membered ring, six-membered ring, or seven-membered ring containing carbon-nitrogen double bonds, or a four-membered ring, five-membered ring, six-membered ring, or seven-membered ring containing carbon-nitrogen single bonds.

[0010] The present invention has found that the compound of formula (1) above, namely the tellurium-containing melanin, has excellent antioxidant capacity, radiation protection capacity and imaging capacity.

[0011] Secondly, the present invention also provides a method for preparing the compound of formula (I) above, the reaction route of which is as follows:

[0012]

[0013] The definitions of R1 and R2 are the same as those above.

[0014] Specifically, compound (II) polymerizes in the presence of an oxidizing agent to generate compound (III). The oxidizing agent may be selected from potassium permanganate, oxygen, sodium periodate, ammonium persulfate, sodium periodate, hydrogen peroxide, sodium hypochlorite, potassium persulfate complex salt, ruthenium tetroxide, cerium ammonium nitrate, manganese dioxide, selenium dioxide, peroxybenzoic acid, m-chloroperoxybenzoic acid, peracetic acid, potassium dichromate, pyridinium dichromate, or ruthenium tetroxide, preferably potassium permanganate or oxygen.

[0015] Specifically, when R1 in compound (II) is H, oxygen is selected as the oxidant, and the reaction rate can be increased in an alkaline environment provided by ammonia monohydrate (NH3·H2O).

[0016] Specifically, when R1 in compound (II) is -COOH, potassium permanganate is selected as the oxidant.

[0017] Specifically, compound (III) reacts with a tellurium cysteine ​​solution to generate compound (I). Optionally, the tellurium cysteine ​​solution further contains GSH solution to improve the stability of tellurium cysteine; preferably, the tellurium cysteine ​​solution further contains tris(2-carboxyethyl) phosphate hydrochloride (TCEP·HCl) to improve the stability of tellurium cysteine. Specifically, the pH of the tellurium cysteine ​​solution is 5-9, preferably 6-8, and more preferably 7.

[0018] Specifically, the reaction time for generating compound (III) can be 10-60 minutes, and the reaction time for generating compound (I) can be overnight. Preferably, after the reaction for generating compound (II) has proceeded for 30 minutes, it is reacted with tellurium cysteine ​​and stirred overnight. Finally, the product is collected by centrifugation, washed, and dialyzed to obtain compound (I).

[0019] Specifically, the tellurium-containing melanin is in the form of spherical nanoparticles, typically with a particle size of approximately 50-300 nm, for example, 80-120 nm. These nanoparticles are generally uniformly spherical, which facilitates their entry into cells, thereby enhancing their antioxidant and radiation protection properties.

[0020] Thirdly, the present invention also provides demonstrations of the preparation of compounds of formula (I) with antioxidant properties, radiation protection properties, and contrast imaging properties. The products include pharmaceuticals, cosmetics, medical protective equipment, and contrast agents.

[0021] Fourthly, the present invention also provides a method for preventing or treating oxidative stress damage or radiation damage, comprising administering a therapeutic dose of the compound of formula (I) above.

[0022] Specifically, the radiation protection performance of the present invention includes radiation protection capability against cells and radiation protection capability against mouse intestines.

[0023] This invention introduces a novel reactive monomer to obtain a previously unreported type of melanin—tellurium-containing melanin—further enhancing its antioxidant efficacy, radiation protection capabilities, and imaging performance. This tellurium-containing melanin, as a novel biomaterial that is simple to prepare, safe to synthesize, biocompatible, and possesses excellent radiation protection properties, holds great promise for wide application in oral medications, topical dressings, cosmetic excipients, medical radiation protection products, nuclear wastewater treatment, and gastrointestinal imaging, demonstrating tremendous application potential. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart illustrating the preparation process of tellurium-containing melanin according to the present invention.

[0026] Figure 2 This is a picture of the solution containing tellurium melanin in Example 1 of the present invention.

[0027] Figure 3This is a transmission electron microscope image of tellurium-containing melanin from Example 1 of the present invention.

[0028] Figure 4 This is an X-ray energy dispersive spectral distribution image of tellurium-containing melanin in Example 1 of the present invention.

[0029] Figure 5 These are the antioxidant capacity test data of tellurium-containing melanin in Example 1 of the present invention.

[0030] Figure 6 This is an in vitro contrast-enhanced CT image of tellurium-containing melanin, as described in Embodiment 1 of the present invention.

[0031] Figure 7 This is the test data from Example 1 of the present invention regarding the removal of excess reactive oxygen species caused by radiation in cells by tellurium-containing melanin.

[0032] Figure 8 This is the test data of Example 1 of the present invention on the protection of cell cycle arrest caused by intracellular radiation by tellurium-containing melanin.

[0033] Figure 9 This is a distribution diagram of tellurium-containing melanin in the gastrointestinal tract of mice after oral administration in Example 1 of the present invention.

[0034] Figure 10 This is a diagram showing the radiation protection effect of oral administration of tellurium-containing melanin on the intestines of mice in Example 1 of the present invention.

[0035] Figure 11 It is a structural characterization of tellurium-containing melanin.

[0036] Chinese-English comparison table

[0037] English Chinese TeMNPs Tellurium melanin L-DOPA Levodopa <![CDATA[KMnO4]]> potassium permanganate <![CDATA[NH3·H2O]]> Ammonia monohydrate TCEP·HCl Tris(2-carboxyethyl) phosphate hydrochloride GSH Reduced glutathione NaOH Sodium hydroxide CT Computed tomography HaCaT Immortalized human keratinocytes HIEC-6 Human small intestinal epithelial cells UV-Vis UV-visible spectroscopy XPS X-ray photoelectron spectroscopy EPR Electron paramagnetic resonance FTIR Fourier transform infrared spectroscopy <![CDATA[ 13 CssNMR]]> <![CDATA[ 13 [C solid-state nuclear magnetic resonance spectrum]]> Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0039] Unless otherwise specified, all raw materials used in the embodiments are commercially available conventional raw materials, and the technical means used are conventional means well known to those skilled in the art.

[0040] The specific preparation flowchart for tellurium-containing melanin is shown below. Figure 1 .

[0041] Example

[0042] This embodiment provides a tellurium-containing melanin—TeMNPs, and its synthesis and preparation steps are as follows:

[0043] First, L-DOPA was dissolved in 20 mL of ultrapure water, then reacted with 240 μL of potassium permanganate (KMnO4) by stirring for 30 minutes. Telluric acid cysteine ​​solution was then added. Stirring continued at room temperature for 24 hours. The product was collected, centrifuged at 11500 rpm for 10 min, washed three times with 6 mL of 1M hydrochloric acid (HCl) and ultrapure water, and then dialyzed to exchange and remove Mn. 2+ Ions. Finally, appropriate aliquots of the solution were lyophilized and weighed to determine the yield of TeMNPs.

[0044] Telluric acid is unstable in air. Therefore, it is produced in situ by reducing telluric acid with tris(2-carboxyethyl) phosphate hydrochloride (TCEP·HCl). The pH is adjusted to 7 with sodium hydroxide (NaOH) solution before use.

[0045] Comparative Example 1

[0046] This comparative example provides a solution of poly-L-DOPANPs nanoparticles, the synthesis and preparation steps of which are as follows:

[0047] First, L-DOPA was dissolved in 20 mL of ultrapure water, then reacted with 240 μL of potassium permanganate (KMnO4) at room temperature for 24 hours with stirring. The product was collected, centrifuged at 11500 rpm for 10 min, washed three times with 6 mL of 1M hydrochloric acid (HCl) and ultrapure water, and then dialyzed again to exchange and remove Mn. 2+ Ions. Finally, appropriate aliquots of the solution were lyophilized and weighed to determine the yield of L-DOPANPs.

[0048] The detection results of TeMNPs- and L-DOPANPs prepared in Example 1 and Comparative Example 1, respectively, are as follows:

[0049]

[0050] 1. Measured by X-ray photoelectron spectroscopy.

[0051] 2. Measured by inductively coupled plasma atomic emission spectrometry.

[0052] Figure 2 This is a picture of the solution state in Example 1. Its concentration is 0.2 mg / mL. -1 .

[0053] Figure 3 The image shown is a transmission electron microscope image of Example 1, which shows that all particles are spherical nanoparticles of uniform size.

[0054] Figure 4 The image shows the X-ray energy dispersive spectral distribution of Example 1, which shows that the Te element on TeMNPs is mainly distributed on the nanoparticles.

[0055] Test case

[0056] (1) Test of intracellular reactive oxygen species scavenged by radiation from tellurium-containing melanin prepared in the example.

[0057] This study selected human intestinal epithelial cells-6 (HIEC-6) and human keratinocytes (HaCaT) as research subjects. This is because the skin is the primary organ exposed to radiation, and the intestines are one of the most radiation-sensitive organs in the human body.

[0058] Depend on Figure 7 It can be seen that in HIEC-6 cells, Example 1 can effectively remove excess reactive oxygen species induced by 6 Gy gamma ray radiation and restore them to normal cell levels. In HaCaT cells, Example 1 can effectively remove excess reactive oxygen species induced by 10 Gy gamma ray radiation and restore them to normal cell levels.

[0059] (2) Tests on the improvement of radiation-induced cell cycle arrest by tellurium-containing melanin prepared in the examples.

[0060] Depend on Figure 8 It can be seen that after HIEC-6 cells were irradiated with 6 Gy gamma rays, and HaCaT cells were irradiated with 10 Gy gamma rays, the cell cycle of both cell types was arrested at the G2 / M phase. Adding Example 1 24 hours before irradiation effectively alleviated the cell cycle arrest in both cell types.

[0061] (3) Test on the relief of radiation-induced intestinal damage in mice after oral administration of the tellurium-containing melanin prepared in the example.

[0062] Depend on Figure 10 It can be seen that after mice were exposed to 6 Gy irradiation, their intestinal structure was significantly damaged, including the disappearance of intestinal villi and epithelial cell apoptosis. However, after mice were subjected to multiple intensive feeding regimens as described in Example 1 before and after irradiation, intact intestinal villi structures were observed 7 days after irradiation, and the intestinal structure was basically consistent with that of normal mice, indicating the strong radiation protection effect of Example 1 in vivo.

[0063] (4) Testing the performance of the tellurium-containing melanin prepared in the examples as a contrast agent

[0064] Depend on Figure 6 It can be seen that, at the same mass concentration, the CT signal intensity of Example 1 is significantly higher than that of Comparative Example 1. Three concentrations (5 mg / mL) -1 10mg mL -1 and 15mg mL -1The CT values ​​(Hounsfield, HU) of TeMNPs were significantly higher than those of L-DOPANP, indicating that the incorporation of Te effectively enhanced radiation protection. Further comparison of the X-ray absorption coefficients of tellurium-containing monomers tellurium cystine and TeMNPs with tellurium concentration revealed that TeMNPs (23.6 HU mg) showed significantly higher CT values ​​(Hounsfield, HU) than L-DOPANP. -1 mL) of tellurium monomer (Te-COOH, 8.5 HU mg) -1 The higher X-ray absorption coefficient of Example 1 (mL) is due to the fact that the conjugated structure of Example 1 also plays a key role in X-ray attenuation, indicating the potential of Example 1 as a contrast agent, especially in gastrointestinal contrast imaging.

[0065] Figure 11 This is a structural characterization of Example 1. Wherein, a is the ultraviolet-visible spectrum (UV-Vis) indicating broadband absorption, b is the X-ray photoelectron spectroscopy (XPS) indicating the presence of tellurium, c is the electron paramagnetic resonance (EPR) indicating the presence of stable free radicals, and d is... 13 C solid-state nuclear magnetic resonance spectrum ( 13 C ssNMR).

[0066] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. Compound of formula (III), in, R1 and R2 are each independently selected from -CH3, -NH2, -COOH, CHO, -C6H5, -OH, -H, -F, -Cl, -Br, -I, and -NO2.

2. The compound of formula (I) according to claim 1, characterized in that, R1 and R2 are each independently selected from -H or -COOH; Optionally, R1 is -H and R2 is -H, or R1 is -COOH and R2 is -COOH; or R1 is -H and R2 is -COOH; or R1 is -COOH and R2 is -H.

3. A method for preparing the compound of formula (I), characterized in that, The reaction route is as follows: Among them, R1 and R2 are each independently selected from -CH3, -NH2, -COOH, CHO, -C6H5, -OH, -H, -F, -Cl, -Br, -I, -NO2; Optionally, R1 and R2 are each independently selected from -H or -COOH; Optionally, R1 is -H and R2 is -H, or R1 is -COOH and R2 is -COOH; or R1 is -H and R2 is -COOH; or R1 is -COOH and R2 is -H. Optionally, the tellurium heterocycle can be a four-membered ring, five-membered ring, six-membered ring, or seven-membered ring containing carbon-nitrogen double bonds, or a four-membered ring, five-membered ring, six-membered ring, or seven-membered ring containing carbon-nitrogen single bonds.

4. The preparation method according to claim 3, characterized in that, Compound (II) polymerizes in the presence of an oxidizing agent to form compound (I); Optionally, the oxidant is selected from at least one of potassium permanganate, sodium periodate, oxygen, ammonium persulfate, sodium periodate, hydrogen peroxide, sodium hypochlorite, potassium persulfate complex salt, ruthenium tetroxide, cerium ammonium nitrate, manganese dioxide, selenium dioxide, peroxybenzoic acid, m-chloroperoxybenzoic acid, peracetic acid, potassium dichromate, pyridinium dichromate, and ruthenium tetroxide, preferably potassium permanganate or oxygen; Optionally, when R1 in compound (II) is -COOH, potassium permanganate or sodium periodate is selected as the oxidant; when R1 in compound (II) is H, oxygen is selected as the oxidant.

5. The preparation method according to claim 3 or 4, characterized in that, Compound (III) reacts with a solution of tellurium cysteine ​​to produce compound (I); Optionally, the tellurium cysteine ​​solution further contains tris(2-carboxyethyl) phosphate hydrochloride; optionally, the tellurium cysteine ​​solution further contains GSH; preferably, the pH of the tellurium cysteine ​​solution is 5-9, more preferably 6-8, and even more preferably pH 7.

6. Containing tellurium melanin, characterized in that, It is prepared by the method described in any one of claims 3-5.

7. The tellurium-containing melanin according to claim 5, characterized in that, The resulting melanin is in the form of spherical nanoparticles; optionally, the particle size is 50-300 nm, preferably 80-120 nm.

8. The compound of formula (I) according to claim 1 or 2 is used to prepare products with antioxidant properties, radiation protection properties, and contrast imaging properties. The products include pharmaceuticals, cosmetics, and medical protective equipment; Optionally, the radiation protection performance includes external X-ray shielding capability and cellular radiation protection capability; Optionally, the contrast imaging capabilities include contrast imaging of the gastrointestinal tract in laboratory animals and humans.

9. A method for providing antioxidant capacity, preventing or treating radiation damage, and imaging, comprising administering a tellurium-containing melanin to a compound of formula (I) as claimed in claim 1 or 2.

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