阅读说明：本技术 一种彝药齿叶蓼提取物及其制备方法和抗癌应用 (Yi medicine polygonum cuspidatum extract as well as preparation method and anticancer application thereof ) 是由 薛永波 苏向东 邓文斌 何鑫 曾子谦 于 2021-08-30 设计创作，主要内容包括：本发明属于天然药物提取物技术领域,具体涉及一种彝药齿叶蓼提取物及其制备方法和抗癌应用,为加强齿叶蓼在抗癌药物及保健品应用方面的研究,提高对齿叶蓼这一民族药用植物的资源开发和利用,本发明提供了一种有效、稳定、安全的制备齿叶蓼块根的不同极性提取部位的方法,所提取得到的齿叶蓼块根乙醇提取物、齿叶蓼块根乙酸乙酯提取物和齿叶蓼块根正丁醇提取物对肺癌细胞、肝癌细胞、乳腺癌细胞、结肠癌细胞和神经母细胞癌细胞均表现出一定的抑制效果。本发明涉及齿叶蓼抗癌有效部位的提取制备工艺流程简易、高效,绿色环保,有利于对何首乌属植物齿叶蓼植物资源的进一步开发。(The invention belongs to the technical field of natural medicine extracts, and particularly relates to a Yi medicine polygonum cuspidatum extract, a preparation method and anticancer application thereof, aiming at strengthening the research of polygonum cuspidatum on the application aspect of anticancer medicines and health care products and improving the resource development and utilization of the polygonum cuspidatum, which is a national medicinal plant. The invention relates to a preparation method of an anticancer effective part of polygonum cuspidatum, which has simple and efficient extraction process flow and is green and environment-friendly and is beneficial to further development of polygonum cuspidatum plant resources of polygonum.)

1. A preparation method of an ethanol extract of polygonum cuspidatum tuberous roots of a Yi medicinal plant is characterized in that polygonum cuspidatum tuberous roots are crushed and sieved, soaked and extracted by an ethanol solvent, filtered and collected after being soaked and extracted, and the extract is concentrated under reduced pressure until no ethanol taste exists, so that the ethanol extract of the polygonum cuspidatum tuberous roots is obtained.

2. A method for preparing a Yi medicinal plant polygonum cuspidatum root ethyl acetate extract is characterized in that the polygonum cuspidatum root ethyl acetate extract in claim 1 is dissolved in distilled water to the maximum extent to form a suspension with uniform concentration, then an ethyl acetate solvent is added for extraction, and the extract is concentrated under reduced pressure until no solvent flavor exists, thus obtaining the polygonum cuspidatum root ethyl acetate extract.

3. A method for preparing n-butanol extract of polygonum cuspidatum root tuber of Yi medicinal plants is characterized in that n-butanol solvent is added into the ethanol extract suspension of claim 2 for extraction, and the extract is concentrated under reduced pressure until no solvent smell exists, thus obtaining the n-butanol extract of polygonum cuspidatum root tuber.

4. The method for preparing ethanol extract of polygonum cuspidatum root tuber of Yi nationality medicinal plant as claimed in claim 1, wherein the material-to-liquid ratio of polygonum cuspidatum root tuber to ethanol solution is 1.0 g: 15-25 mL of ethanol solution is 95% ethanol solution.

5. The method for preparing the ethyl acetate extract of the polygonum cuspidatum root for medicinal use of the Yi nationality according to claim 2, wherein the volume of the ethyl acetate solvent is 1-1.5 times of the volume of the ethanol extract suspension.

6. The method for preparing n-butanol extract of polygonum cuspidatum root tuber as a medicinal herb of the Yi nationality as claimed in claim 3, wherein the volume of n-butanol solvent added is 1-1.5 times of that of ethanol extract suspension.

7. The ethanol extract of the polygonum cuspidatum root tuber prepared by the preparation method of claim 1 or 4, or the ethyl acetate extract of the polygonum cuspidatum root tuber prepared by the preparation method of claim 2 or 5, or the n-butanol extract of the polygonum cuspidatum root tuber prepared by the preparation method of claim 3 or 6.

8. The use of the ethanol extract of the polygonum denticulatum root tuber or the ethyl acetate extract of the polygonum denticulatum root tuber or the n-butanol extract of the polygonum denticulatum root tuber in the preparation of anti-cancer drugs as claimed in claim 7.

9. The use of the ethanol extract of the polygonum denticulatum root tuber or the ethyl acetate extract of the polygonum denticulatum root tuber or the n-butanol extract of the polygonum denticulatum root tuber as claimed in claim 7 in the preparation of medicaments for inhibiting the proliferation of tumor cells.

10. The use according to claim 9, wherein said tumor cells comprise lung cancer cells (a549), liver cancer cells (SMMC-7721), breast cancer cells (MCF-7), colon cancer cells (SW480) and neuroblast cancer cells (SH-SY 5Y).

Technical Field

The invention belongs to the technical field of medicinal extracts, and particularly relates to a Yi medicine polygonum cuspidatum extract as well as a preparation method and anticancer application thereof.

Background

Cancer is an important disease that seriously harms human health. According to statistical data published in the international agency for research on cancer (IARC) the 2020 world report on cancer, it has been shown that in 2020, there are approximately 1930 million new cases of cancer worldwide and 1000 million cases of cancer death, with a mortality rate of lung cancer of up to 18.0%, followed by colon cancer (9.4%), liver cancer (8.3%), stomach cancer (7.7%) and breast cancer (6.9%). In the future, the cancer is the high-grade year of the global cancer, and if urgent measures are not taken in each country, 2840 million new cancer cases appear in the world every year by 2040. Therefore, the task of preventing and treating cancer is very difficult, and research and development work of anticancer drugs is actively invested in all countries in the world.

The rapid development of life science research makes people continuously and deeply know the pathogenesis, physiological change and pathological mechanism of malignant tumor. Meanwhile, with the gradual elucidation of various basic processes such as signal transduction, cell cycle regulation, apoptosis, angiogenesis, cell metastasis and infiltration in tumor cells, a plurality of antitumor drugs are developed. However, most of the developed antitumor drugs are chemically synthesized, and have the problems of poor selectivity, large toxic and side effects, drug resistance and the like. Therefore, the search for effective anticancer natural drugs from plants has become a hot research topic for pharmaceutical researchers at home and abroad. In recent 40 years from 1981 to 2019, 64.4% of the antitumor drugs that have been marketed are derived from natural products or derivatives thereof. Such as paclitaxel (Taxol) derived from Taxus Chinensis (Taxus Chinensis); camptothecin (Camptothecine) of Camptotheca acuminata (Camptotheca acuminata) of Davidiaceae. Many medicinal plants have thousands of years of medicinal history in folks, and have a thick medical clinical medication basis. Therefore, the research and development of new natural anticancer drugs from medicinal plant resources has huge potential and application prospect.

Polygonum denticulatum [ Fallopia Denticuta (Huangga. J. Li) ] is a perennial winding herbaceous plant of Polygonum genus (Fallopia) of Polygonaceae family (Polygonaceae), and is mainly distributed in Yunnan (Yunnan, Dianzhong and northwest Yunnan) in south China, Guizhou and other areas. The root tuber of the polygonum cuspidatum is enlarged and nearly spherical, has hard texture and powdery property, and is a common traditional herbal medicine for people of the Yi nationality. The medicinal value is recorded in 'Yunnan herbal medicine selection' and 'Qujing Special district Chinese herbal medicine handbook' of 1970 edition at first, namely Maotai, Jiantou, Chidanhong, etc. According to the records of the medical classics, the polygonum cuspidatum root tuber is bitter in taste, astringent and cool in property, and has the effects of astringing and checking diarrhea, diminishing inflammation and stopping dysentery, and the main applicable diseases comprise digestive tract diseases such as dyspepsia, stomachache and dysentery; chronic hepatitis; menoxenia; metrorrhagia and metrostaxis, etc.; the external use can treat traumatic hemorrhage; the initial stage of furuncle. However, Polygonum dentatum as a ethnic herb with traditional medicinal experience has not been regarded as important, and the research on the Polygonum dentatum is relatively delayed. At present, there is no report on the application of polygonum cuspidatum in preparing anticancer drugs or health care products.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a preparation method of a Yi medicinal plant polygonum cuspidatum extract, the preparation process flow is simple, efficient and environment-friendly, the extracted parts with different polarities have certain inhibition effects on lung cancer cells (A549), liver cancer cells (SMMC-7721), breast cancer cells (MCF-7), colon cancer cells (SW480) and neuroblast cancer cells (SH-SY5Y), and the further development and utilization of the polygonum cuspidatum which is a popular herb resource in the nationality are facilitated.

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

the invention provides a method for preparing ethanol extract of polygonum cuspidatum root tuber, which is a Yi medicinal plant, and specifically comprises the following steps: crushing and sieving the polygonum cuspidatum root tuber, soaking and extracting by using an ethanol solution, filtering and collecting an extracting solution after soaking and extracting, and then concentrating the extracting solution under reduced pressure until no ethanol smell exists to obtain the polygonum cuspidatum root tuber ethanol extract.

The invention also provides a preparation method of the ethyl acetate extract of the Yi medicinal plant polygonum cuspidatum root, which specifically comprises the following steps: dissolving the ethanol extract of the polygonum cuspidatum root tuber in water to the maximum extent to form uniform suspension, then adding an ethyl acetate solvent for extraction, and concentrating the extract until no solvent smell exists to obtain the polygonum cuspidatum root ethyl acetate extract.

The invention also provides a preparation method of the n-butanol extract of the medicinal plant polygonum cuspidatum root tuber of the Yi nationality, which comprises the following steps: and (3) adding the n-butyl alcohol solvent into the suspension of the ethanol extract for extraction, and finally concentrating until no solvent smell exists to obtain the n-butyl alcohol extract of the polygonum cuspidatum root tuber.

Preferably, in the extraction process of the polygonum cuspidatum root tuber ethanol extract, the material-liquid ratio of the polygonum cuspidatum root tuber to the ethanol solution is 1.0 g: 15-25 mL of ethanol solution is 95% ethanol solution.

Preferably, the ethanol extract of the polygonum cuspidatum root tuber is concentrated under reduced pressure at 45 + -5 deg.C under vacuum degree of 0.04 + -0.02 MPa.

Preferably, in the extraction process of the polygonum cuspidatum root tuber ethanol extract, the soaking is carried out for 24-36 hours at the temperature of 20 +/-5 ℃, and the soaking process is repeated for 3-4 times.

Preferably, in the extraction process of the polygonum cuspidatum root tuber ethanol extract, the filtration adopts a pressure suction filtration method, and the standing is carried out before the filtration until the liquid is clear and the filtration is carried out until no dregs exist.

Preferably, in the extraction process of the polygonum cuspidatum root tuber ethyl acetate extract, the addition volume of the ethyl acetate solvent is 1-1.5 times of the suspension, and the extraction process is repeated.

Preferably, in the extraction process of the polygonum cuspidatum root n-butanol extract, the volume of the n-butanol solvent is 1-1.5 times of that of the suspension.

Preferably, the temperature of decompression concentration is 50 +/-5 ℃ and the vacuum degree is 0.04 +/-0.02 MPa in the extraction process of the polygonum cuspidatum root ethyl acetate extract and the extraction process of the polygonum cuspidatum root n-butyl alcohol extract.

Preferably, in the extraction of the polygonum cuspidatum root tuber ethyl acetate extract and the extraction of the polygonum cuspidatum root normal-butanol extract, the extraction times of the polygonum cuspidatum root tuber ethyl acetate extract and the polygonum cuspidatum root normal-butanol extract are 3-4 times respectively.

The invention also provides the polygonum cuspidatum root tuber ethanol extract, the polygonum cuspidatum root tuber ethyl acetate extract or the polygonum cuspidatum root normal butanol extract prepared by the preparation method.

The invention also provides application of the polygonum cuspidatum root tuber ethanol extract or the polygonum cuspidatum root tuber ethyl acetate extract or the polygonum cuspidatum root n-butanol extract in preparing an anti-cancer medicament.

The invention also provides application of the polygonum cuspidatum root tuber ethanol extract or the polygonum cuspidatum root tuber ethyl acetate extract or the polygonum cuspidatum root n-butanol extract in preparing a medicament for inhibiting tumor cell proliferation.

Preferably, the tumor cells include lung cancer cells (A549), liver cancer cells (SMMC-7721), breast cancer cells (MCF-7), colon cancer cells (SW480) and neuroblast cancer cells (SH-SY 5Y).

The invention researches the in-vitro anti-tumor effects of different polarity extraction parts (polygonum cuspidatum tuberous root ethanol extract, polygonum cuspidatum tuberous root ethyl acetate extract and polygonum cuspidatum tuberous root n-butyl alcohol extract) of polygonum cuspidatum tuberous root on lung cancer (A549), liver cancer (SMMC-7721), breast cancer (MCF-7), colon cancer (SW480) and neuroblast cell cancer (SH-SY5Y) by adopting an MTS method, wherein the ethanol extract and the ethyl acetate extract of the polygonum cuspidatum tuberous root have obvious inhibition rate on the in-vitro proliferation of the neuroblast cell cancer cells (SH-SY5Y), the ethyl acetate extract and the n-butyl alcohol extract have obvious inhibition rate on the in-vitro proliferation of the colon cancer (SW480), and the ethyl acetate extract has inhibition rate on the in-vitro proliferation of the liver cancer (SMMC-7721) and the breast cancer (MCF-7) to a certain degree Has important application potential in the research and development of anti-cancer drugs.

Compared with the prior art, the invention has the beneficial effects that:

in order to strengthen the research of the polygonum cuspidatum in the application aspect of anticancer drugs and health care products and improve the resource development degree of the polygonum cuspidatum which is a national medicinal plant, the invention provides an effective, stable and safe method for preparing different polarity extraction parts of the polygonum cuspidatum tuberous root, and the extracted polygonum cuspidatum tuberous root ethanol extract, polygonum cuspidatum tuberous root ethyl acetate extract and polygonum cuspidatum tuberous root n-butyl alcohol extract show certain inhibition effects on lung cancer cells (A549), liver cancer cells (SMMC-7721), breast cancer cells (MCF-7), colon cancer cells (SW480) and neuroblast cancer cells (SH-SY5Y), thereby indicating that the polygonum cuspidatum has potential application value in the research and development aspect of anticancer drugs. The extraction and preparation process flow of the polygonum cuspidatum anticancer effective part is simple and efficient, green and environment-friendly, and can promote the development and utilization of polygonum cuspidatum plant resources of polygonum.

The invention firstly evaluates the anticancer activity of the different polarity extraction parts of the polygonum cuspidatum root tuber, provides the medicinal value of the polygonum cuspidatum except for the folk common use for treating digestive tract diseases and hemorrhage, namely the application of the different polarity extraction parts of the polygonum cuspidatum root tuber in the aspect of preparing antitumor drugs, and is beneficial to the continuous development and utilization of the polygonum cuspidatum which is a common folk herbal medicine resource of the Yi nationality.

Drawings

FIG. 1 shows the anti-cell proliferation activity of the extracts of Polygonum cuspidatum root tuber with different polarities on 5 cancer cell lines;

FIG. 2 is a graph showing the anti-cell proliferation activity of an ethanol extract and an ethyl acetate extract of a polygonum cuspidatum root tuber on a neuroblast cancer (SH-SY5Y) cell line;

FIG. 3 is a graph showing the anti-cell proliferation activity of an ethyl acetate extract and an n-butanol extract of Polygonum cuspidatum root tuber on colon cancer (SW480) cell line;

FIG. 4 is a diagram showing the anti-cell proliferation activity of an ethyl acetate extract of Polygonum cuspidatum root tuber on breast cancer (MCF-7) and liver cancer (SMMC-7721) cell lines.

Detailed Description

The following further describes the embodiments of the present invention. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The experimental procedures in the following examples were carried out by conventional methods unless otherwise specified, and the test materials used in the following examples were commercially available by conventional methods unless otherwise specified.

The following examples relate to pharmaceutical materials, reagents and apparatus:

(1) medicinal materials and reagents

The root tuber of Polygonum denticulatum is collected from Chenjin county of Bijie city, Guizhou province, and identified as root tuber of Polygonum denticulatum [ Fallopia denticuta (Huangga. J.Li) ] of Polygonum of Polygonaceae by professor Huang Sheng of Hubei national university.

Fetal bovine serum (FBS, Hyclone), pancreatin (Hyclone), RMPI1640 or DMEM high and DMEM low sugar (Hyclone, Logan, UT, USA), tetramethylazoazolium salt (MTT, Sigma, st.louis, MO, USA), dimethyl sulfoxide (DMSO, Sigma), cisplatin and paclitaxel (Sigma), and further, 95% ethanol, ethyl acetate and n-butanol were all in-house analytical purity.

(2) Five cancer cell lines were purchased from ATCC (Manassas, VA, USA): lung cancer cells (A549), liver cancer cells (SMMC-7721), breast cancer cells (MCF-7), colon cancer cells (SW480) and neuroblast cancer cells (SH-SY 5Y).

(3) The instrument comprises the following steps: a Hadoffer rotary evaporator (Hei-VAP Core ML); electronic balance, multi-functional microplate reader (multistkan FC).

Example 1 preparation of different polarity extracted parts of Polygonum denticulatum root tuber

(1) Drying in the shade, powdering hard root tuber of herba Polygoni Ciliinerve, sieving with 40 mesh sieve, and sieving according to the weight ratio of 1: adding 95% ethanol solution into 20(g/mL) of the materials, fully stirring and uniformly mixing, and soaking at room temperature (20 +/-5 ℃). In the soaking process, the soaked samples are fully stirred once every 4 hours, and are soaked for 24 hours.

(2) And (2) standing the ethanol extracting solution obtained in the step (1) until the liquid is clear, then filtering the extracting solution by a pressure suction filtration method, and repeating the suction filtration step for 3 times until no medicine residue exists.

(3) And (3) repeating the step (1) and the step (2), soaking and extracting the polygonum cuspidatum root tuber for 3-4 times for 24 hours, and collecting all extracting solutions.

(4) And (4) concentrating the ethanol extract collected in the step (3) under reduced pressure (the temperature is 45 +/-5 ℃ and the vacuum degree is 0.04 +/-0.02 Mpa) until the concentrate has no ethanol smell, so as to obtain the polygonum cuspidatum tuberous root ethanol extract.

(5) According to the extract: distilled water 1: 1-1: 2, the ethanol extract is dissolved to the maximum extent to form a uniform suspension.

(6) And (3) adding an ethyl acetate solvent with the volume of 1-1.5 times of that of the suspension obtained in the step (5), extracting for 3 times, combining the 3 times of extraction liquid, and concentrating under reduced pressure (the temperature is 50 +/-5 ℃, and the vacuum degree is 0.04 +/-0.02 Mpa) until no solvent smell exists, so as to obtain the polygonum cuspidatum tuberous root ethyl acetate extract.

(7) And (4) after the extraction in the step (6) is finished, continuously adding an n-butyl alcohol solvent with the volume of 1-1.5 times into the suspension, extracting for 3 times by using the solvent, combining the extraction solutions for 3 times, and concentrating under reduced pressure (the temperature is 50 +/-5 ℃, and the vacuum degree is 0.04 +/-0.02 Mpa) until no solvent smell exists, thus obtaining the n-butyl alcohol extract of the polygonum cuspidatum root tuber.

Example 2 application of different extraction parts of Polygonum denticulatum root tuber in research and development of anticancer drugs

(1) Principle for detecting cell activity by MTS method

MTS is a novel MTT analogue, is called 3- (4, 5-dimethylthiozol-2-yl) -5 (3-carboxymethyloxyphenyl) -2- (4-sulfopheny) -2H-tetrazolium, and is a yellow dye. Succinate dehydrogenase in the mitochondria of living cells can metabolize and reduce MTS to generate soluble Formazan (Formazan) compounds, and the content of the Formazan can be measured at 490nm by using an enzyme labeling instrument. Since the formazan production amount is generally proportional to the number of living cells, the number of living cells can be estimated from the optical density OD value.

(2) Experimental methods

1) Inoculating cells: preparing single cell suspension by using culture solution (DMEM or RMPI1640) containing 10% fetal calf serum, inoculating the single cell suspension into a 96-well plate at the density of 3000-12000 cells per well, wherein the inoculation volume of each well is 100 mu L, and the cells are inoculated and cultured 12-24 hours in advance.

2) Adding the solution of the extract to be detected: the ethanol extract, ethyl acetate extract and n-butanol extract prepared in example 1 were dissolved in DMSO and added to the 96-well plate of step (1), and each extract was sieved at a concentration of 100. mu.g/mL, 20. mu.g/mL, 4. mu.g/mL, 0.8. mu.g/mL, 0.16. mu.g/mL, with a final volume of 200. mu.L per well, with 3 replicates per treatment.

3) Color development: adding the extract to be tested, culturing the cells at 37 ℃ for 48 hours, removing the culture solution in each well, and adding 20 mu L of MTS solution and 100 mu L of culture solution in each well; setting 3 blank multiple wells (mixed solution of 20 mu L MTS solution and 100 mu L culture solution), and continuing incubation for 2-4 hours to ensure that the light absorption value is measured after the reaction is fully performed.

4) Color comparison: selecting 492nm wavelength, reading light absorption value of each well with multifunctional microplate reader (MULTISKAN FC), drawing cell growth curve with extract concentration as abscissa and cell survival rate as ordinate, and calculating IC of compound by two-point method (Reed and Muench method)₅₀The value is obtained.

5) Positive control compound: two positive compounds of cisplatin (DDP) and paclitaxel (Taxol) are set in each experiment, then a cell growth curve is drawn by taking the concentration as the abscissa and the cell survival rate as the ordinate, and the IC of the compound is calculated by using a two-point method (Reed and Muench method)₅₀The value is obtained.

(3) Results of the experiment

As shown in the results of FIG. 1, the ethanol extract, the ethyl acetate extract and the n-butanol extract all have certain inhibitory effects on lung cancer cells (A549), liver cancer cells (SMMC-7721), breast cancer cells (MCF-7), colon cancer cells (SW480) and neuroblast cancer cells (SH-SY 5Y). Wherein the ethanol extract has the best effect in inhibiting growth and proliferation of neuroblastoma cells (SH-SY5Y), and the drug effect has concentration dependence and IC₅₀The value was 30.1. + -. 0.67. mu.g/mL.

As shown in the results of FIGS. 2 and 4, the ethyl acetate extract showed the best inhibitory effect on both neuroblastoma (SH-SY5Y) and liver cancer (SMMC-7721) cells, and the drug effect showed concentration dependence and IC₅₀The values were 36.6. + -. 1.37. mu.g/mL and 59.5. + -. 3.86. mu.g/mL, respectively. Meanwhile, fig. 3 and 4 can be used to realize the above-described effectsIt is shown that the ethyl acetate extract has certain effect of inhibiting the growth and proliferation of breast cancer (MCF-7) and colon cancer (SW480) cells, and the drug effect shows concentration dependence and IC₅₀The values were 95.4. + -. 1.07. mu.g/mL and 77.2. + -. 2.11. mu.g/mL, respectively (see FIGS. 3 and 4).

In addition, as can be seen from FIG. 3, n-butanol extract had a good inhibitory effect on the growth and proliferation of colon cancer (SW480) cells, and the drug effect was concentration-dependent, IC₅₀The value was 72.1. + -. 1.06. mu.g/mL.

In conclusion, the extracts of the polygonum cuspidatum tuberous roots with different polarities, such as the ethanol extract, the ethyl acetate extract, the n-butanol extract and the like, have the inhibition effect on the growth and proliferation of different tumor cells and have potential anti-tumor activity. Wherein, the ethyl acetate has inhibitory effect on four tumor cells, namely neuroblastoma cell (SH-SY5Y), liver cancer (SMMC-7721), breast cancer (MCF-7) and colon cancer (SW480), namely the anti-tumor activity is obviously better than that of ethanol extract and n-butanol extract. Interestingly, the ethanol extract and the ethyl acetate extract both had a significant growth proliferation inhibitory effect on neuroblastoma cells (SH-SY5Y) (FIG. 2), while the ethyl acetate extract and the n-butanol extract had a significant growth proliferation inhibitory effect on colon cancer (SW480) (FIG. 3). In addition, the ethyl acetate extract inhibited the activity of liver cancer (SMMC-7721) and breast cancer (MCF-7) cells to some extent (FIG. 4). Therefore, the polygonum cuspidatum of polygonum has potential anticancer medicinal efficacy, and provides theoretical basis for better developing the application of the traditional medicinal plants of the Yi nationality of polygonum cuspidatum in the research and development of anticancer drugs.

The embodiments of the present invention have been described in detail, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, and the scope of protection is still within the scope of the invention.