Mint extract as well as preparation method and application thereof

Abstract

The invention provides a mint extract and a preparation method and application thereof, and belongs to the technical field of traditional Chinese medicine extracts.The preparation method comprises the following steps that mint powder and an ethanol solution are mixed, treated at 45-55 DEG C for 50-70 min and then subjected to ultrasonic extraction 1-5 times, and the mint extract is obtained; the mass volume ratio of the mint powder to the ethanol solution is 1g: (25-35) mL; the temperature of the ultrasonic extraction is 45-55 DEG C, the power of the ultrasonic extraction is 650-750W, and the time of each ultrasonic extraction is 30-50 minutes. The mint extract provided by the invention can significantly reduce serum uric acid, creatinine and urea nitrogen levels of HUA mice; kidney injury caused by hyperuricemia is improved, and the uric acid level of an organism is reduced by inhibiting the activity of xanthine oxidase in serum and liver.

Description

Technical Field

[0001] The invention belongs to the technical field of traditional Chinese medicine extraction, and in particular relates to a peppermint extract and a preparation method and application thereof. Background Art

[0002] Hyperuricemia (HUA) is a metabolic disorder that is widely seen around the world, mainly manifested by an imbalance in the production and excretion of uric acid in the body. Uric acid is the end product of purine metabolism in the human body. Usually, about 75% of uric acid is excreted through the kidneys to maintain physiological balance. When the production of uric acid in the body increases or the excretion function of the kidneys is hindered, the level of uric acid in the serum increases, leading to the occurrence of HUA. HUA is not only closely related to the onset of gout, but may also promote or aggravate many metabolic-related diseases, such as cardiovascular disease, renal failure, hypertension, hyperlipidemia, diabetes, and metabolic syndrome. Under the premise of balanced nutrition and normal purine intake, the laboratory diagnostic criteria for HUA are mainly based on the measurement of serum uric acid (SUA) concentration. If the fasting SUA level of adult males on different days continues to exceed 420 μmol / L, or adult females exceed 360 μmol / L, they are diagnosed with HUA.

[0003] The prevalence of HUA has shown a clear upward trend and is becoming younger. In the biochemical metabolic process, the production of uric acid is the final result of purine metabolism, and xanthine oxidase (XOD) is the key enzyme in UA synthesis. Therefore, the increase in XOD activity in the liver is one of the main causes of HUA.

[0004] The normal excretion mechanism of uric acid in the kidney plays a decisive role in maintaining SUA levels, and insufficient uric acid excretion accounts for about 90% of the total cases. Under normal physiological conditions, 70% of urate is excreted through a variety of uric acid transporters (URAT1, GLUT9, OAT4, OAT1, OAT3, etc.), which jointly regulate the filtration, reabsorption and secretion of UA in the kidney. Impaired renal function or excessive reabsorption of uric acid by the renal tubules can lead to uric acid excretion disorders, thereby increasing SUA levels and ultimately causing HUA.

[0005] The main method for preventing and treating HUA is to reduce the level of uric acid (UA) in the body, which can be achieved by inhibiting the production of urate or promoting its excretion. At present, drugs used for the treatment of HUA are divided into two categories: one is xanthine oxidase inhibitors used to reduce uric acid production, such as allopurinol and febuxostat; the other is uricosurics that increase uric acid excretion, such as benzbromarone and probenecid. However, long-term use of the above drugs will produce serious side effects, such as allopurinol triggering allergic reactions and nephrotoxicity in the body, febuxostat increasing the risk of cardiovascular death, and benzbromarone increasing hepatotoxicity. Therefore, the development of new uric acid-lowering drugs with high efficiency and more ideal safety for the treatment of hyperuricemia remains an indispensable task. Summary of the invention

[0006] In view of this, the object of the present invention is to provide a peppermint extract and a preparation method and application thereof; the peppermint extract prepared according to the preparation method provided by the present invention can significantly reduce the levels of serum uric acid, creatinine, and urea nitrogen in HUA mice; improve kidney damage caused by high uric acid, and inhibit the activity of xanthine oxidase in serum and liver to reduce the body's uric acid level.

[0007] The invention provides a method for preparing a mint extract, comprising the following steps: mixing mint powder with an ethanol solution, treating at 45-55° C. for 50-70 min, and ultrasonically extracting for 1-5 times to obtain the mint extract;

[0008] The mass volume ratio of the mint powder to the ethanol solution is 1 g: 25-35 mL;

[0009] The temperature of the ultrasonic extraction is 45-55° C., the power of the ultrasonic extraction is 650-750 W, and the time of each ultrasonic extraction is 30-50 min.

[0010] Preferably, the volume concentration of the ethanol solution is 35% to 45%.

[0011] Preferably, the ultrasonic extraction is performed 2 to 4 times.

[0012] Preferably, the mint powder is obtained by freeze-drying, crushing and sieving mint leaves; the sieving is through a 40-mesh sieve.

[0013] Preferably, the mint variety is orange mint.

[0014] Preferably, after the ultrasonic extraction, the method further comprises the steps of reduced pressure concentration and freeze drying.

[0015] Preferably, the temperature of the reduced pressure concentration is 34-36° C., and the time of the reduced pressure concentration is 20-40 min.

[0016] The invention provides a mint extract prepared by the preparation method. The mint extract has a total flavonoid content of 65.5% to 66.15% and a total polyphenol content of 5.4% to 5.45%.

[0017] The invention provides application of the peppermint extract in preparing a medicine for treating hyperuricemia.

[0018] The invention provides application of peppermint extract in preparing medicine for treating kidney damage caused by hyperuricemia.

[0019] The invention provides application of the peppermint extract in preparing food or health products for assisting in maintaining normal uric acid levels.

[0020] Compared with the prior art, the present invention has the following beneficial effects: the preparation method of the peppermint extract provided by the present invention comprises mixing peppermint powder with an ethanol solution, treating at 45 to 55° C. for 50 to 70 minutes, and ultrasonically extracting for 1 to 5 times to obtain the peppermint extract; the peppermint extract prepared by the present invention can significantly reduce the levels of serum uric acid, creatinine, and urea nitrogen in HUA mice; increase the level of glutathione in the kidney; reduce the level of malondialdehyde in the kidney; improve the total antioxidant capacity of the kidney; improve kidney damage caused by high uric acid, and reduce the body's uric acid level by inhibiting the activity of xanthine oxidase in serum and liver. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the TIC diagram of mint extract ME under positive and negative ion modes;

[0022] Figure 2 The effect of peppermint extract ME on serum uric acid in HUA mice;

[0023] Figure 3 The effect of peppermint extract ME on serum creatinine in HUA mice;

[0024] Figure 4 The effect of peppermint extract ME on serum urea nitrogen in HUA mice;

[0025] Figure 5 The effect of peppermint extract ME on serum xanthine oxidase in HUA mice;

[0026] Figure 6 The effect of peppermint extract ME on xanthine oxidase in liver of HUA mice;

[0027] Figure 7 The effect of peppermint extract ME on renal glutathione in HUA mice;

[0028] Figure 8 The effect of peppermint extract ME on malondialdehyde in the kidney of HUA mice;

[0029] Fig. 9 The effect of peppermint extract ME on the total antioxidant capacity of kidney in HUA mice;

[0030] Fig.10 The effect of peppermint extract ME on H&E of HUA mouse kidneys, the scale bar length is 200 μm;

[0031] Figures 2 to 9 In: “*” indicates p<0.05, “**” indicates p<0.01, “***” indicates p<0.001, and “****” indicates p<0.0001. DETAILED DESCRIPTION

[0032] The invention provides a preparation method of a mint extract, comprising the following steps: mixing mint powder with an ethanol solution, treating at 45-55° C. for 50-70 min, and ultrasonically extracting for 1-5 times to obtain the mint extract; the mass volume ratio of the mint powder to the ethanol solution is 1 g: 25-35 mL; the temperature of the ultrasonic extraction is 45-55° C., the power of the ultrasonic extraction is 650-750 W, and the time of each ultrasonic extraction is 30-50 min.

[0033] In the present invention, firstly, mint powder is mixed with ethanol solution; the mint powder is preferably obtained by freeze-drying, crushing and sieving mint leaves. In the present invention, the variety of mint is orange mint, and the source of orange mint is not particularly limited in the present invention, and conventional commercial products in the field can be used. In the present invention, fresh mint leaves are preferably used, washed and freeze-dried; the washing is preferably carried out with purified water or distilled water; the freeze-drying temperature is -85℃~-75℃, preferably -80℃; the freeze-drying time is 10~14h. The present invention is crushed after the freeze-drying, and the present invention does not specifically limit the crushing method, and the conventional crushing method in the field can be used; the present invention is sieved after the crushing, and the sieving is preferably through a 40-mesh sieve, and the components under the sieve are collected to obtain mint powder. In the present invention, the mint powder is preferably sealed and stored, and the storage temperature is preferably -18~-22℃. The present invention mixes the mint powder with an ethanol solution; the volume concentration of the ethanol solution is preferably 35%~45%, more preferably 38%~42%, and most preferably 40%. In the present invention, the mass volume ratio of the mint powder to the ethanol solution is preferably 1 g: 25-35 mL, more preferably 1 g: 28-32 mL, and most preferably 30 mL.

[0034] In the present invention, after mixing the mint powder with the ethanol solution, the mixture is treated at 45-55° C. for 50-70 minutes. In the present invention, the treatment is preferably carried out by water bath heating, the treatment temperature is preferably 47-53° C., more preferably 50° C.; the treatment time is preferably 55-65 minutes, more preferably 60 minutes. In the present invention, the treatment is used to increase the yield of flavonoids.

[0035] The present invention performs ultrasonic extraction after the treatment, and the temperature of the ultrasonic extraction is 45-55°C, preferably 48-52°C, and more preferably 50°C; the power of the ultrasonic extraction is 650-750W, preferably 670-730W, and more preferably 700W; the number of ultrasonic extractions is preferably 2-4 times, and more preferably 3 times; the time of each ultrasonic extraction is 30-50min, preferably 35-45min, and more preferably 40min. After the ultrasonic extraction is completed, the present invention preferably combines all the extracts, filters, and collects the supernatant; the filtration is preferably carried out by qualitative filter paper filtration.

[0036] The present invention preferably further comprises the steps of reduced pressure concentration and freeze drying after the ultrasonic extraction. In the present invention, the reduced pressure concentration is preferably rotary evaporation concentration; the temperature of the reduced pressure concentration is preferably 34 to 36°C, more preferably 35°C; the time of the reduced pressure concentration is preferably 20 to 40 minutes, preferably 25 to 35 minutes, more preferably 30 minutes. In the present invention, the temperature of the freeze drying is preferably -85°C to -75°C, more preferably -80°C; the time of the freeze drying is preferably 10 to 14 hours, more preferably 12 hours.

[0037] The invention provides a mint extract prepared by the preparation method. The mint extract has a total flavonoid content of 65.5% to 66.15% and a total polyphenol content of 5.4% to 5.45%.

[0038] The present invention also provides application of the peppermint extract in preparing a medicine for treating hyperuricemia.

[0039] The invention provides application of peppermint extract in preparing medicine for treating kidney damage caused by hyperuricemia.

[0040] In the present invention, the peppermint extract can reduce the level of xanthine oxidase in serum or liver, improve the oxidative stress level of kidney tissue, and improve kidney damage caused by high uric acid.

[0041] The invention provides application of the peppermint extract in preparing food or health products for assisting in maintaining normal uric acid levels.

[0042] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0043] Example 1

[0044] 1. Materials and methods

[0045] 1.1 Materials

[0046] Orange mint was purchased from Beijing Panglong Flower and Tree Horticulture Co., Ltd.

[0047] 1.2 Reagents

[0048] Potassium oxonate (Sigma Bioreagent Co., Ltd.); hypoxanthine (Shanghai Adamas Reagent Co., Ltd.); allopurinol (Shanghai Yuanye Biotechnology Co., Ltd.); uric acid (UA) detection kit (Nanjing Jiancheng Bioengineering Institute); creatinine (CRE) detection kit (Nanjing Jiancheng Bioengineering Institute); urea nitrogen (BUN) detection kit (Nanjing Jiancheng Bioengineering Institute); xanthine oxidase (XOD) detection kit (Nanjing Jiancheng Bioengineering Institute); malondialdehyde (MDA) determination kit (Nanjing Jiancheng Bioengineering Institute); reduced glutathione (GSH) determination kit (Nanjing Jiancheng Bioengineering Institute); total antioxidant capacity (T-AOC) determination kit (Nanjing Jiancheng Bioengineering Institute).

[0049] 1.3 Experimental instruments

[0050] ELISA reader (Thermo Tisher Scientific); high-speed refrigerated centrifuge (Sigma-Aldrich); electric constant temperature water bath (Beijing Changan Yongchuang Scientific Instrument Co., Ltd.);

[0051] 1.4 Experimental methods

[0052] 1.4.1 Extraction of peppermint extract ME

[0053] Wash the fresh mint with pure water, freeze at -80℃ overnight, dry in a freeze dryer, crush through a 40-mesh sieve, seal, and store at -20℃ for later use. Weigh fresh orange mint powder in a conical flask, add 40% ethanol solution according to the solid-liquid ratio of 1g:30mL, seal, heat in a 50℃ water bath for 1h, ultrasonically control for 40min at 700W power, repeat three times, filter, evaporate and concentrate the supernatant using a rotary evaporator at 35℃ for 30min, freeze-dry the concentrate using a freeze dryer, and store at -80℃ for later use.

[0054] 1.4.2 Determination of total flavonoids, total polyphenols and compound composition

[0055] Determination of total flavonoids: using NaNO2 -AI(NO 3 ) 3 Colorimetric method. Weigh 10 mg of rutin standard dried to constant weight, dissolve and dilute to 50 mL with 70% ethanol, shake well, and use as standard solution. Take 0.0, 0.3, 0.6, 0.9, 1.2, 1.5, 1.8 mL of standard solution in 10 mL test tubes, add 0.15 mL of 5% sodium nitrite, shake well and let stand for 5 min, then add 0.15 mL of 10% aluminum nitrate, shake well and let stand for 5 min, then add 1.0 mL of 4% sodium hydroxide, add 30% ethanol to 5 mL, shake well and let stand for 15 min, use Wahaha water as blank to zero, measure absorbance at a wavelength of 510 nm, and draw a standard curve to obtain the regression equation. Take 1 mL of peppermint extract solution with a concentration of 0.4 mg / mL, and the determination method is the same as the standard curve determination. Calculate the total flavonoid content according to the standard curve standard equation.

[0056] Determination of total phenol: Folin phenol method. Weigh 0.1g of gallic acid and dilute to 100mL with Wahaha water. Take 1mL and dilute to 10mL volumetric flask to prepare a 0.1mg / mL standard solution. Take 0.2, 0.4, 0.6, 0.8, and 1.0mL of the standard solution from the standard solution into a 25mL volumetric flask, and add 1mL of Folin phenol reagent and 10mL of 7% Na 2 CO 3 Solution, mix well, dilute to 25mL with Wahaha water, keep it in dark for 1h, and measure the absorbance at 750nm. Take 1mL of 0.5mg / mL peppermint extract solution, add 1mL of Folin phenol reagent and 10mL of 7% Na 2 CO 3 Solution, mix well, dilute to 25mL with Wahaha water, keep in dark for 1h, and measure absorbance at 750nm. Measure standard curve with gallic acid as standard. Calculate total phenol content according to standard curve standard equation.

[0057] Ultra-high performance liquid chromatography-mass spectrometry and high-resolution mass spectrometry (LC-MS) were used to detect peppermint extract (ME). A chromatographic column Hypersil GoldAQ C18 column (10.0 mm × 2.1 mm, 1.9 min m, Thermo Fisher) was used, the column temperature was 35 ° C, the injection volume was 5 μL, and the Dionex Ultimate3000RSLC system (Thermo Fisher) was used. The gradient elution flow rate was 0.4 mL / min, the eluent A was 0.1% formic acid-acetonitrile, and the eluent B was 0.1% formic acid-water. Elution conditions: 0-2 min, 5% A; 2-40 min, 5-95% A; 40-45 min, 95% A; 40-40.1 min, 95% A; 45.1-50 min, 5% A. The detection was carried out in full scan mode, and the samples were detected in positive and negative ion modes respectively. The resolution was 70,000 (half-maximum width 200 m / z). The scanning range was 100-1500 m / z. Nitrogen was used as the auxiliary gas, and the sheath gas and sweep gas were set to flow rates of 45, 15, and 0, respectively. The spray voltage was 3.2 KV for the positive electrode, 2.8 KV for the negative electrode, 60 V for the S-lens RF, and the auxiliary gas heater temperature and the capillary temperature were both controlled at 350 °C. The secondary NCE20-60 was adjusted according to the compound. All the acquired data were collected and processed by the software Xcalbur4.0 (ThermoScience, USA).

[0058] 1.4.3 Experimental evaluation of the effect of peppermint extract ME on lowering uric acid

[0059] 1.4.3.1 Animal grouping and treatment

[0060] A total of 72 6-week-old, 35g Kunming male mice were selected. Kunming mice were purchased from Spef (Beijing) Biotechnology Co., Ltd., mouse maintenance feed was purchased from Beijing Keao Xieli Feed Co., Ltd., and high uric acid model feed (containing 0.25% adenine + 2% potassium oxonic acid + 97.75% normal feed) was purchased from Beijing Keao Xieli Feed Co., Ltd.

[0061] The mice were adaptively raised in an environment with a relative humidity of 50%-70%, a constant temperature of 25±2℃, and a 12h day and night alternation for one week. During this period, the mice were fed with ordinary feed and had free access to water. After one week, the mice were randomly divided into a blank group and a model group. The blank group was gavaged with normal saline (10μL / g) every morning, and the model group was gavaged with potassium oxonate (PO, 500mg / kg) and hypoxanthine (I, 300mg / kg) every day for one week. After one week, the serum uric acid value of the mice was measured. The serum uric acid value was significantly higher than that of the blank group, which was a successful model. The model mice were then randomly divided into five groups: model group (MD), allopurinol group (AP), low-dose (150mg / kg) peppermint extract group (LME), medium-dose (300mg / kg) peppermint extract group (MME), and high-dose (600mg / kg) peppermint extract group (HME), with 12 mice in each group. The above-mentioned treatment groups were all prepared with normal saline as the solvent to the corresponding concentration, and gavage treatment was performed at 0.1mL / 10g. The dosage of each group is shown in Table 1. After the last administration, the mice were fasted for 12 h, serum was collected, and tissues such as kidney and liver were dissected for subsequent biochemical index determination.

[0062] Table 1 Dosage of each group

[0063]

[0064]

[0065] 1.4.3.2 Serum biochemical index detection

[0066] Kits were used to detect serum uric acid (UA), creatinine (CRE), and urea nitrogen (BUN) levels.

[0067] 1.4.3.3 Serum and liver XOD detection

[0068] The xanthine oxidase (XOD) levels in serum and liver were detected using a kit.

[0069] 1.4.3.4 Observation and evaluation of renal tissue pathology

[0070] Hematoxylin-eosin (H&E) staining was used to evaluate the effects of ME on mouse kidney tissue.

[0071] 2. Results and Analysis

[0072] 2.1 The contents of total flavonoids, total polyphenols and main compound components in peppermint extract ME are shown in Tables 2 and 3.

[0073] Table 2 Contents of total flavonoids and total polyphenols in peppermint extract

[0074]

[0075] Table 3 Main compounds in peppermint extract

[0076]

[0077]

[0078]

[0079] Effects of 2.2ME on serum uric acid, creatinine and urea nitrogen levels in mice

[0080] like Figure 2 As shown in the figure, compared with the UA (81.12 μmol / L) in the normal control group, the UA level in the MD group (153.94 μmol / L) was significantly increased (p<0.0001), indicating that the HUA model was successfully established. The UA level (16.63 μmol / L) of HUA mice in the allopurinol group was significantly reduced (p<0.0001), and the SUA levels in the low, medium, and high dose groups were significantly reduced to 120.23, 102.99, and 86.36 μmol / L, respectively. The results show that allopurinol and menthol extracts can effectively promote uric acid excretion and reduce the uric acid content in HUA mice.

[0081] like Figure 3 As shown in the figure, the SCR level in the MD group was significantly higher than that in the CON group (p<0.0001), indicating kidney damage in HUA mice. Compared with the HUA group, the serum creatinine content in the AP group was higher than that in the HUA group (p<0.05), indicating that while AP treated HUA, it further aggravated the damage of HUA to glomerular filtration, thereby aggravating the kidney damage in mice. After intervention with high, medium, and low doses of extracts, kidney damage caused by HUA was alleviated to a certain extent.

[0082] like Figure 4 As shown in the figure, compared with the CON group, the BUN level of mice in the MD group increased significantly (P<0.0001). Combined with the SCR level of mice in the MD group, it shows that HUA can cause certain kidney damage. Compared with the MD group, the BUN level of the AP group also increased significantly (P<0.0001), further indicating that although allopurinol has the effect of reducing the uric acid level in mice, it will further increase the kidney damage in mice. Compared with the MD group, the serum urea nitrogen levels of the three extract groups decreased significantly (P<0.0001), especially the HME group, which decreased significantly (P<0.0001). The above results show that menthol extract can help alleviate the kidney damage caused by HUA to a certain extent while reducing the uric acid level.

[0083] Effects of 3ME on serum and liver XOD in mice

[0084] Figure 5 ,6 The effects of ME on serum and liver XOD activity in HUA mouse models induced by potassium oxonate and hypoxanthine were demonstrated. XOD is a key enzyme in the uric acid synthesis pathway. It can catalyze the production of uric acid. Therefore, changes in its activity directly affect uric acid levels and are a key target for HUA treatment research. The results showed that compared with the CON group, the serum and liver XOD activities of the MD group were significantly increased (p<0.0001), indicating that uric acid synthesis in HUA mice was increased. After treatment with three concentrations of ME, the serum and liver XOD activities of mice showed a significant dose-dependent decrease, especially in the HME group, where the decrease effect was the most significant (p<0.0001). This suggests that ME may have a significant inhibitory effect on XOD in vivo, thereby effectively reducing the production of uric acid. In addition, compared with the AP group, ME showed similar effects in reducing XOD activity, further emphasizing its potential therapeutic value in regulating uric acid metabolism. Combined with these analysis results, ME may exert its effect of reducing serum uric acid levels by inhibiting XOD activity. Given that XOD is a key enzyme controlling uric acid production, inhibition of its activity may be one of the mechanisms by which ME slows the development of HUA.

[0085] Effects of 2.4ME on oxidative stress level in mouse kidney tissue

[0086] GSH, MDA and T-AOC are classic indicators reflecting the level of oxidative stress in body tissues. Figure 7 , 8 As shown in Figure 9, compared with the CON group, the levels of GSH and T-AOC in the kidney tissue of the mice in the MD group were significantly reduced, while the level of MDA was significantly increased, indicating that the renal lipid peroxidation and antioxidant capacity of hyperuricemia rats decreased, and a certain oxidative stress occurred. After oral administration of peppermint extract, the levels of GSH (p < 0.0001) and T-AOC (p < 0.0001) in the kidney tissue of hyperuricemia mice were significantly increased, and the level of MDA was significantly reduced (p < 0.0001). The above results show that peppermint extract inhibited the oxidative stress response in the kidney tissue of hyperuricemia mice to a certain extent.

[0087] Effects of 2.5ME on renal tissue pathology in mice

[0088] After HE staining, it can be observed that the glomerular morphology of the normal control group is normal, the glomerular capillary structure is clear, and no inflammatory cell infiltration is observed in the renal interstitium. Compared with the normal control group, the kidneys of the mice in the model group were significantly damaged, the medullary structure was unclear, the tubular epithelial cells showed obvious edema, the tubular lumen was significantly dilated and vacuolated, and there was obvious inflammatory cell infiltration in the renal interstitium. Although allopurinol can effectively reduce the serum UA, Cr, and BUN levels of hyperuricemia mouse models and reduce the activity of liver XO, it cannot alleviate kidney damage, and the tubular epithelial cells show obvious edema and vacuolar degeneration. The renal tissue of hyperuricemia mice treated with low-dose LME was pink and loose, and the cells showed obvious edema. After treatment with medium and high doses, the renal tubular dilation and vacuolation of HUA mice were significantly improved, especially the kidney sections of the high-dose group were closest to the blank group, further proving that peppermint extract can alleviate renal damage in HUA mice. The experimental results show that ME has a renal protective effect and can alleviate renal damage caused by PO-induced hyperuricemia mice.

[0089] Based on the above embodiments and test examples, it can be seen that the peppermint extract treatment of the present invention can effectively inhibit the uric acid level of hyperuricemia model mice, improve the renal damage of hyperuricemia model mice, and reduce uric acid production by inhibiting xanthine oxidase activity, thereby achieving the purpose of treating hyperuricemia and improving renal damage.

[0090] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a peppermint extract, characterized in that: The following steps are involved: The mint powder is mixed with the ethanol solution, treated at 45-55° C. for 50-70 min, and then ultrasonically extracted for 1-5 times to obtain a mint extract; The mass volume ratio of the mint powder to the ethanol solution is 1 g: 25-35 mL; The temperature of the ultrasonic extraction is 45-55° C., the power of the ultrasonic extraction is 650-750 W, and the time of each ultrasonic extraction is 30-50 min.

2. The preparation method according to claim 1, characterized in that: The volume concentration of the ethanol solution is 35% to 45%.

3. The preparation method according to claim 1, characterized in that: The ultrasonic extraction is performed 2 to 4 times.

4. The preparation method according to claim 1, characterized in that: The mint powder is obtained by freeze-drying, crushing and sieving mint leaves; the sieving is through a 40-mesh sieve.

5. The preparation method according to claim 4, characterized in that: The variety of the mint is orange mint.

6. The preparation method according to claim 1, characterized in that: After the ultrasonic extraction, the method further comprises the steps of reduced pressure concentration and freeze drying; the temperature of the reduced pressure concentration is 34 to 36° C., and the time of the reduced pressure concentration is 20 to 40 minutes.

7. The peppermint extract prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The mint extract has a total flavonoid content of 65.5% to 66.15% and a total polyphenol content of 5.4% to 5.45%.

8. Use of the peppermint extract according to claim 7 in the preparation of a medicament for treating hyperuricemia.

9. Use of the peppermint extract according to claim 7 in the preparation of a medicament for treating renal damage caused by hyperuricemia.

10. Use of the peppermint extract according to claim 7 in preparing food or health products that assist in maintaining normal uric acid levels.

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