Houttuynia cordata extract and preparation method thereof

Abstract

The invention discloses a kind of Herba Houttuyniae extract and preparation method thereof, comprise the following steps:S1, Herba Houttuyniae rhizome is added in mixed acid aqueous solution after being crushed, immersion treatment, obtain Herba Houttuyniae mixed liquor;S2, Herba Houttuyniae mixed liquor is adjusted to pH 4 5, adds pectinase, primary enzymolysis, enzyme inactivation, adjusts pH to 6 7, adds complex enzyme, secondary enzymolysis, enzyme inactivation, obtains enzymolysis solution;S3, menthol is added to enzymolysis solution, water extraction, obtains water extract and filter residue;S4, filter residue is added in ethanol, then salicylic acid, diacetyl tartaric acid mono- and diglycerides are added, alcohol extraction, filter, obtain alcohol extract;S5, water extract is mixed with alcohol extract, decompression distillation, obtains Herba Houttuyniae extract.The present invention can effectively improve the extraction yield of polysaccharide and flavonoids in Herba Houttuyniae, and meanwhile, the Herba Houttuyniae extract prepared has better antioxidant property, has good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of plant extracts, and particularly relates to a houttuynia cordata extract and a preparation method thereof. Background Art

[0002] Houttuynia cordata, also known as Houttuynia cordata, Cen grass, Side ear root, and smelly smelling grass, is the whole herb of the Houttuynia cordata plant in the Saururaceae family. It is a perennial herb. In my country, Houttuynia cordata is primarily distributed in the central, southeastern, and southwestern provinces south of the Yangtze River, with a particular prevalence in Sichuan, Hubei, Zhejiang, Fujian, Guangxi, and Guizhou.

[0003] Houttuynia cordata is a plant resource with great development potential, serving as both a medicine and a food. Its chemical composition is complex, with major compounds including flavonoids, alkaloids, volatile oils, polysaccharides, terpenes, and sterols. Modern pharmacological research has demonstrated that Houttuynia cordata extracts possess diverse biological activities, including anti-inflammatory, antiviral, anti-allergic, antibacterial, antioxidant, anti-tumor, and immunomodulatory activities. Clinically, Houttuynia cordata is primarily used to treat dysentery, colds and fevers, mumps, and acute icteric hepatitis. Compound Houttuynia cordata tablets and Houttuynia cordata eye drops are already widely used clinically.

[0004] However, other bioactive components of Houttuynia cordata, such as flavonoids and water-soluble polysaccharides, have received little attention. Flavonoids primarily refer to compounds based on 2-phenylchromone, typically found in many plants as free aglycones or as glycosides bound to sugars. Flavonoids are potent scavengers of reactive oxygen free radicals. A significant portion of today's emerging natural health foods is associated with anti-aging and free radical scavenging, suggesting that flavonoids may be the bioactive factors underlying these benefits. Polysaccharides are widely found in the tissues of animals, plants, and microorganisms. They are a class of naturally occurring high-molecular-weight compounds composed of various monosaccharides. Various types of cellulose, pectin, and mucilage all function as structural polysaccharides. Polysaccharides are organic compounds found in nature with a broad spectrum of chemical structures and biological functions. They are widely found in plants, animals, and microorganisms, and have demonstrated immune regulation, anti-tumor, antiviral, blood sugar and lipid lowering, and anti-aging effects.

[0005] Chinese patent application CN108530548A discloses a method for preparing a Houttuynia cordata polysaccharide extract, comprising the following steps: (1) crushing fresh Houttuynia cordata, adding purified water at a solid-liquid ratio of 1:60-65 g / mL, extracting at a pH of 7-7.5 and a temperature of 85-90°C for 120-160 min, and filtering to obtain a filtrate a and a Houttuynia cordata filter residue; (2) refluxing the Houttuynia cordata filter residue with ether for 160-180 min, centrifuging, drying the filter residue at 40°C, refluxing with ethanol for 220-250 min, centrifuging, drying the filter residue at 40°C, adding 40 times the amount of deionized water, extracting in a water bath at 85-90°C for 10 h, repeating four times, and collecting by centrifugation to obtain a filtrate b; (3) mixing the filtrate a and the filtrate b, concentrating under reduced pressure, and drying to obtain a Houttuynia cordata polysaccharide extract. The Houttuynia cordata polysaccharide of the invention has a high extraction rate and is relatively pure. Chinese patent application CN104906238A discloses a method for preparing total flavonoids from Houttuynia cordata. The method comprises: drying Houttuynia cordata in the shade, pulverizing it, adding 1-2 times the amount of 50-60% ethanol to the raw material, and mixing and homogenizing it in a homogenizer; after homogenization, the material is placed in an ultrasonic device, and a 50-60% ethanol solution 3-5 times the amount of the raw material is added. Ultrasonic extraction is performed for 90-120 minutes, followed by concentration under reduced pressure and ethanol recovery to obtain a concentrate; the resulting concentrate is applied to an 80-100 mesh polyamide resin column, eluted, and the eluate is collected, concentrated, and dried to obtain the total flavonoids from Houttuynia cordata. This invention offers advantages such as rapidity, high efficiency, low solvent usage, good reproducibility, and reusable resin.

[0006] However, the above patents only extract a single active ingredient from Houttuynia cordata and are unable to simultaneously extract the polysaccharides and flavonoids from Houttuynia cordata. Therefore, it is of great significance to develop a new method for extracting Houttuynia cordata extract and to improve the extraction rate of polysaccharides and flavonoids from Houttuynia cordata. Summary of the Invention

[0007] In view of the deficiencies of the prior art, the present invention aims to provide a herba houttuyniae extract and a preparation method thereof, which can effectively improve the extraction rate of polysaccharides and flavonoids in herba houttuyniae. At the same time, the prepared herba houttuyniae extract has better antioxidant properties and good application prospects.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A method for preparing a houttuynia cordata extract comprises the following steps:

[0010] S1. Pretreatment of Houttuynia cordata: washing and drying the rhizomes of Houttuynia cordata, crushing the rhizomes, adding the rhizomes to a mixed acid aqueous solution, and immersing the rhizomes to obtain a Houttuynia cordata mixed solution;

[0011] S2, complex enzyme enzymolysis: the Houttuynia mixed solution in step S1 is adjusted to a pH of 4-5, and then pectinase is added to perform a primary enzymolysis. After the enzymolysis is completed, the enzyme is inactivated. The pH is adjusted to 6-7, and the complex enzyme is added to perform a secondary enzymolysis. After the enzymolysis is completed, the enzyme is inactivated to obtain an enzymolysis solution;

[0012] S3, preparation of aqueous extract: adding menthol to the enzymatic hydrolyzate in step S2, performing aqueous extraction, filtering after the aqueous extraction is completed to obtain an aqueous extract and a filter residue, and drying the filter residue for later use;

[0013] S4, preparation of an alcohol extract: adding the filter residue from step S3 to ethanol, followed by adding salicylic acid and diacetyl tartaric acid mono- and diglycerides, and performing alcohol extraction under ultrasonic conditions. After the alcohol extraction is completed, filtering is performed to obtain an alcohol extract;

[0014] S5. Preparation of Houttuynia cordata extract: uniformly mix the water extract in step S3 and the alcohol extract in step S4, and then perform reduced pressure distillation to remove the solvent to obtain the Houttuynia cordata extract.

[0015] Preferably, the mesh size of the Houttuynia cordata powder after the pulverization in step S1 is 80-120 mesh, and the temperature of the immersion treatment is 30-40° C., and the time is 2-3 hours.

[0016] Preferably, the mixed acid aqueous solution in step S1 is composed of malic acid, tartaric acid and water, the concentration of malic acid is 7-10 g / L, and the concentration of tartaric acid is 3-5 g / L; the solid-liquid ratio of the Houttuynia cordata rhizome to the mixed acid aqueous solution is 1:10-15.

[0017] In the present invention, Houttuynia cordata is treated with a mixed acid. The malic acid in the mixed acid can partially hydrolyze components such as cellulose, hemicellulose and pectin in the plant cell wall, thereby loosening the cell wall structure and facilitating subsequent enzymatic hydrolysis and solvent penetration. Tartaric acid has certain antioxidant and chelating effects. The antioxidant properties can protect easily oxidized components such as flavonoids in Houttuynia cordata and reduce their loss during the extraction process. Compared with other inorganic acids and organic acids, the mixed acid has a milder effect on Houttuynia cordata, reduces damage to polysaccharides and flavonoids, and increases the content of polysaccharides and flavonoids in subsequent extracts.

[0018] Preferably, the amount of pectinase added in step S2 is 0.5-0.8% of the mass of the rhizome of Houttuynia cordata, and the temperature of the primary enzymatic hydrolysis is 45-50° C., and the time is 1-2 h.

[0019] Preferably, the complex enzyme in step S2 is a mixture of cellulase and xylanase in a mass ratio of 5-7:3-5, the amount of the complex enzyme added is 1-1.2% of the mass of the Houttuynia cordata rhizome, the temperature of the secondary enzymatic hydrolysis is 40-45°C, and the time is 30-50min.

[0020] In the present invention, a two-step enzymatic hydrolysis process allows for more thorough degradation of different cell wall components, improving extraction efficiency. Initial enzymatic hydrolysis using pectinase reduces cell wall integrity and reduces resistance to the dissolution of intracellular substances. Subsequently, a complex enzyme is added: cellulase hydrolyzes cellulose in the cell wall, while xylanase hydrolyzes hemicellulose in the cell wall. The combined action of these two enzymes maximizes the cell wall destruction, fully releasing intracellular substances and improving the polysaccharide extraction rate.

[0021] Preferably, the amount of menthol added in step S3 is 0.07-0.1% of the mass of the enzymatic hydrolysate, the water extraction temperature is 80-90° C., and the time is 1-2 h.

[0022] In the present invention, by adding menthol to the enzymatic hydrolysis solution and then performing water extraction, after the complex enzyme hydrolyzes the cell wall, the menthol can accelerate the penetration of the solvent into the cell, accelerate the dissolution of intracellular substances, shorten the extraction time and improve the yield.

[0023] Preferably, in step S4, the material-liquid ratio of the filter residue to ethanol is 1:8-12, the amount of salicylic acid added is 0.2-0.3% of the mass of the filter residue, and the amount of diacetyl tartaric acid mono- and diglycerides added is 0.3-0.5% of the mass of the filter residue.

[0024] In the present invention, salicylic acid and diacetyl tartaric acid mono- and diglycerides are added during the alcohol extraction process. Salicylic acid has certain antioxidant and anti-inflammatory effects and may form complexes with certain flavonoid compounds, making it easier to extract the flavonoids. Diacetyl tartaric acid mono- and diglycerides have certain cell membrane penetration ability, which helps ethanol enter the cells and improves the extraction rate of flavonoids.

[0025] Preferably, the power of the ultrasound in step S4 is 60-70 W, the frequency is 30-40 kHz, the temperature of the alcohol extraction is 60-65° C., and the time is 1-2 h.

[0026] Preferably, the pressure of the reduced pressure distillation in step S5 is 5-10 kPa.

[0027] The present invention also protects a herba houttuyniae extract prepared by the above method.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The preparation method of Houttuynia cordata extract provided by the present invention realizes the efficient simultaneous extraction of polysaccharides and flavonoids by mixed acid pretreatment and multi-stage enzymatic hydrolysis technology; a mixed acid system of malic acid and tartaric acid is used to effectively loosen the plant cell wall structure under mild conditions, and through the synergistic action of the pectinase-cellulase-xylanase complex enzyme system, cellulose, hemicellulose and pectin in the cell wall are directionally decomposed, significantly improving the dissolution rate of cell contents; then, step-by-step water extraction and ultrasound-assisted alcohol extraction processes are combined to efficiently extract water-soluble polysaccharides and alcohol-soluble flavonoids respectively; compared with traditional single extraction methods, the present invention can simultaneously obtain high-yield polysaccharides and flavonoids, avoiding waste of resources and improving the comprehensive utilization value of Houttuynia cordata.

[0030] (2) The preparation method of Houttuynia cordata extract provided by the present invention innovatively uses a mixed acid solution of malic acid and tartaric acid in the pretreatment stage. Malic acid can more gently hydrolyze the cell wall of Houttuynia cordata, loosening the structure and creating favorable conditions for subsequent enzymatic hydrolysis and solvent penetration. Tartaric acid has antioxidant and chelating effects, which can protect polysaccharides and flavonoids from damage, thereby improving the yield and quality of the target product; subsequently, a two-step enzymatic hydrolysis process is adopted in the enzymatic hydrolysis stage with the synergistic action of pectinase and complex enzymes (cellulase and xylanase). Pectinase can effectively degrade the pectin component in the cell wall and reduce the resistance to the dissolution of intracellular substances; the complex enzyme further acts on cellulose and hemicellulose, more thoroughly destroying the cell wall structure and promoting the release of polysaccharides and flavonoids. This enzymatic hydrolysis combination fully considers the composition characteristics of the cell wall of Houttuynia cordata, has strong targeting and high enzymatic hydrolysis efficiency.

[0031] (3) The preparation method of Houttuynia cordata extract provided by the present invention includes the following steps: introducing menthol in the water extraction stage, which can accelerate the penetration of the solvent into the cells and shorten the extraction time; introducing salicylic acid and diacetyl tartaric acid mono- and diglycerides as extraction aids in the alcohol extraction stage; the synergistic effect of these agents can effectively destroy the hydrogen bond between flavonoids and lignin, promote the permeability of cell membranes, further improve the extraction rate of flavonoid compounds, and inhibit the activity of polyphenol oxidase to avoid the oxidation loss of flavonoid components; at the same time, the cavitation effect of ultrasound also helps to rupture cells and dissolve the target components. Through the comprehensive use of these extraction aids, the extraction process is made more efficient and thorough, thereby effectively improving the extraction rate of polysaccharides and flavonoids in Houttuynia cordata, and the prepared Houttuynia cordata extract has better antioxidant properties. DETAILED DESCRIPTION

[0032] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] Example 1

[0034] A method for preparing a houttuynia cordata extract comprises the following steps:

[0035] S1. Pretreatment of Houttuynia cordata: Wash and dry the rhizomes of Houttuynia cordata, crush them into 100 mesh, add them into a mixed acid aqueous solution (malic acid concentration is 9 g / L, tartaric acid concentration is 4 g / L), the solid-liquid ratio of Houttuynia cordata rhizomes to the mixed acid aqueous solution is 1:13, and immerse them at 35°C for 2.5 hours to obtain a Houttuynia cordata mixed solution;

[0036] S2, enzymatic hydrolysis of complex enzymes: add 0.1 mol / L sodium hydroxide solution to the Houttuynia cordata mixed solution in step S1, adjust the pH to 4.5, then add pectinase (0.7% of the mass of Houttuynia cordata rhizome), enzymolysis at 48°C for 1.5 h, inactivate the enzyme in boiling water for 10 min after the enzymatic hydrolysis is completed, add 0.1 mol / L sodium hydroxide solution to adjust the pH to 6.5, add complex enzyme (cellulase and xylanase in a mass ratio of 6:4), the amount of complex enzyme added is 1.1% of the mass of Houttuynia cordata rhizome, enzymolysis at 43°C for 40 min, inactivate the enzyme in boiling water for 10 min after the enzymatic hydrolysis is completed, and obtain an enzymatic solution;

[0037] S3, preparation of aqueous extract: adding menthol (0.09% by mass of the aqueous extract) to the enzymatic hydrolysate in step S2, extracting with water at 85°C for 1.5h, filtering after the aqueous extraction to obtain an aqueous extract and a filter residue, and drying the filter residue for later use;

[0038] S4, preparation of alcohol extract: the filter residue in step S3 was added to ethanol, the solid-liquid ratio of the filter residue to ethanol was 1:10, followed by adding salicylic acid (0.25% of the filter residue mass) and diacetyl tartaric acid mono- and diglycerides (0.4% of the filter residue mass), and alcohol extraction was performed under ultrasonic conditions, the ultrasonic power was 65 W, the frequency was 35 kHz, the alcohol extraction temperature was 63 ° C, the time was 1.5 h, and after the alcohol extraction was completed, the alcohol extract was filtered to obtain the alcohol extract;

[0039] S5. Preparation of Houttuynia cordata extract: The water extract in step S3 and the alcohol extract in step S4 are mixed evenly, and then the solvent is removed by vacuum distillation at a pressure of 7 kPa to obtain the Houttuynia cordata extract.

[0040] Example 2

[0041] A method for preparing a houttuynia cordata extract comprises the following steps:

[0042] S1. Pretreatment of Houttuynia cordata: Wash and dry the rhizomes of Houttuynia cordata, crush them into 100 mesh, add them into a mixed acid aqueous solution (malic acid concentration is 8 g / L, tartaric acid concentration is 4 g / L), the solid-liquid ratio of Houttuynia cordata rhizomes to the mixed acid aqueous solution is 1:12, and immerse them at 35°C for 2.5 hours to obtain a Houttuynia cordata mixed solution;

[0043] S2, enzymatic hydrolysis of complex enzyme: add 0.1 mol / L sodium hydroxide solution to the Houttuynia cordata mixed solution in step S1, adjust the pH to 4.5, then add pectinase (0.6% of the mass of Houttuynia cordata rhizome), enzymolysis at 47°C for 1.5 h, inactivate the enzyme in boiling water for 10 min after the enzymolysis is completed, add 0.1 mol / L sodium hydroxide solution to adjust the pH to 6.5, add complex enzyme (cellulase and xylanase in a mass ratio of 7:3), the amount of complex enzyme added is 1.1% of the mass of Houttuynia cordata rhizome, enzymolysis at 42°C for 40 min, inactivate the enzyme in boiling water for 10 min after the enzymolysis is completed, and obtain an enzymolysis solution;

[0044] S3, preparation of aqueous extract: adding menthol (0.08% by mass of the hydrolyzate) to the enzymatic hydrolyzate in step S2, extracting with water at 85°C for 1.5h, filtering after the extraction to obtain an aqueous extract and a filter residue, and drying the filter residue for later use;

[0045] S4, preparation of alcohol extract: the filter residue in step S3 was added to ethanol, the solid-liquid ratio of the filter residue to ethanol was 1:10, followed by adding salicylic acid (0.25% of the filter residue mass) and diacetyl tartaric acid mono- and diglycerides (0.4% of the filter residue mass), and alcohol extraction was performed under ultrasonic conditions, the ultrasonic power was 65 W, the frequency was 35 kHz, the alcohol extraction temperature was 62 ° C, the time was 1.5 h, and after the alcohol extraction was completed, the alcohol extract was filtered to obtain the alcohol extract;

[0046] S5. Preparation of Houttuynia cordata extract: The water extract in step S3 and the alcohol extract in step S4 are mixed evenly, and then the solvent is removed by vacuum distillation at a pressure of 8 kPa to obtain the Houttuynia cordata extract.

[0047] Example 3

[0048] A method for preparing a houttuynia cordata extract comprises the following steps:

[0049] S1. Pretreatment of Houttuynia cordata: Wash and dry the rhizomes of Houttuynia cordata, crush them into 80 mesh size, add them into a mixed acid aqueous solution (malic acid concentration is 7 g / L, tartaric acid concentration is 3 g / L), the solid-liquid ratio of Houttuynia cordata rhizomes to the mixed acid aqueous solution is 1:10, and immerse them at 30° C. for 3 h to obtain a Houttuynia cordata mixed solution;

[0050] S2, enzymolysis with complex enzymes: add 0.1 mol / L sodium hydroxide solution to the Houttuynia cordata mixed solution in step S1 to adjust the pH to 4, then add pectinase (0.5% of the mass of the Houttuynia cordata rhizome), and enzymolyze at 45°C for 2 hours. After the enzymolysis is completed, inactivate the enzyme in boiling water for 10 minutes, add 0.1 mol / L sodium hydroxide solution to adjust the pH to 6, add complex enzyme (cellulase and xylanase in a mass ratio of 5:5), the amount of the complex enzyme added is 1% of the mass of the Houttuynia cordata rhizome, and enzymolyze at 40°C for 50 minutes. After the enzymolysis is completed, inactivate the enzyme in boiling water for 10 minutes to obtain an enzymolyzed solution;

[0051] S3, preparation of aqueous extract: adding menthol (0.07% by mass of the aqueous extract) to the enzymatic hydrolysate in step S2, extracting with aqueous solution at 80°C for 2h, filtering after the aqueous extraction to obtain an aqueous extract and a filter residue, and drying the filter residue for later use;

[0052] S4, preparation of alcohol extract: the filter residue in step S3 was added to ethanol, the solid-liquid ratio of the filter residue to ethanol was 1:8, and then salicylic acid (0.2% of the mass of the filter residue) and diacetyl tartaric acid mono- and diglycerides (0.3% of the mass of the filter residue) were added, and alcohol extraction was performed under ultrasonic conditions, the ultrasonic power was 60 W, the frequency was 40 kHz, the alcohol extraction temperature was 60 ° C, the time was 2 h, and after the alcohol extraction was completed, the alcohol extract was filtered to obtain the alcohol extract;

[0053] S5. Preparation of Houttuynia cordata extract: The water extract in step S3 and the alcohol extract in step S4 are mixed evenly, and then the solvent is removed by vacuum distillation at a pressure of 10 kPa to obtain the Houttuynia cordata extract.

[0054] Example 4

[0055] A method for preparing a houttuynia cordata extract comprises the following steps:

[0056] S1. Pretreatment of Houttuynia cordata: Wash and dry the rhizomes of Houttuynia cordata, crush them into 120 mesh size, add them into a mixed acid aqueous solution (malic acid concentration is 10 g / L, tartaric acid concentration is 5 g / L), the solid-liquid ratio of Houttuynia cordata rhizomes to the mixed acid aqueous solution is 1:15, and immerse them at 40°C for 2 hours to obtain a Houttuynia cordata mixed solution;

[0057] S2, enzymolysis with complex enzymes: add 0.1 mol / L sodium hydroxide solution to the Houttuynia cordata mixed solution in step S1, adjust the pH to 5, then add pectinase (0.8% of the mass of Houttuynia cordata rhizome), enzymolysis at 50°C for 1 hour, inactivate the enzyme in boiling water for 10 minutes after the enzymolysis is completed, add 0.1 mol / L sodium hydroxide solution to adjust the pH to 7, add complex enzyme (cellulase and xylanase in a mass ratio of 7:3), the amount of complex enzyme added is 1.2% of the mass of Houttuynia cordata rhizome, enzymolysis at 45°C for 30 minutes, inactivate the enzyme in boiling water for 10 minutes after the enzymolysis is completed, and obtain an enzymolysis solution;

[0058] S3, preparation of aqueous extract: adding menthol (0.1% by mass of the aqueous extract) to the enzymatic hydrolysate in step S2, extracting with water at 90°C for 1 hour, filtering after the aqueous extraction to obtain an aqueous extract and a filter residue, and drying the filter residue for later use;

[0059] S4, preparation of alcohol extract: the filter residue in step S3 was added to ethanol, the solid-liquid ratio of the filter residue to ethanol was 1:12, followed by adding salicylic acid (0.3% of the filter residue mass) and diacetyl tartaric acid mono- and diglycerides (0.5% of the filter residue mass), and alcohol extraction was performed under ultrasonic conditions, the ultrasonic power was 70 W, the frequency was 30 kHz, the alcohol extraction temperature was 65 ° C, the time was 1 h, and after the alcohol extraction was completed, the alcohol extract was filtered to obtain the alcohol extract;

[0060] S5. Preparation of Houttuynia cordata extract: The water extract in step S3 and the alcohol extract in step S4 are mixed evenly, and then the solvent is removed by vacuum distillation at a pressure of 5 kPa to obtain the Houttuynia cordata extract.

[0061] Comparative Example 1

[0062] A method for preparing a houttuynia cordata extract comprises the following steps:

[0063] S1. Pretreatment of Houttuynia cordata: Wash and dry the rhizomes of Houttuynia cordata, crush them into 100 mesh, add them into a citric acid aqueous solution (concentration: 13 g / L), with the ratio of Houttuynia cordata rhizomes to the citric acid aqueous solution being 1:13, and immerse them at 35°C for 2.5 hours to obtain a Houttuynia cordata mixed solution;

[0064] S2, enzymatic hydrolysis of complex enzymes: add 0.1 mol / L sodium hydroxide solution to the Houttuynia cordata mixed solution in step S1, adjust the pH to 4.5, then add pectinase (0.7% of the mass of Houttuynia cordata rhizome), enzymolysis at 48°C for 1.5 h, inactivate the enzyme in boiling water for 10 min after the enzymatic hydrolysis is completed, add 0.1 mol / L sodium hydroxide solution to adjust the pH to 6.5, add complex enzyme (cellulase and xylanase in a mass ratio of 6:4), the amount of complex enzyme added is 1.1% of the mass of Houttuynia cordata rhizome, enzymolysis at 43°C for 40 min, inactivate the enzyme in boiling water for 10 min after the enzymatic hydrolysis is completed, and obtain an enzymatic solution;

[0065] S3, preparation of aqueous extract: adding menthol (0.09% by mass of the aqueous extract) to the enzymatic hydrolysate in step S2, extracting with water at 85°C for 1.5h, filtering after the aqueous extraction to obtain an aqueous extract and a filter residue, and drying the filter residue for later use;

[0066] S4, preparation of alcohol extract: the filter residue in step S3 was added to ethanol, the solid-liquid ratio of the filter residue to ethanol was 1:10, followed by adding salicylic acid (0.25% of the filter residue mass) and diacetyl tartaric acid mono- and diglycerides (0.4% of the filter residue mass), and alcohol extraction was performed under ultrasonic conditions, the ultrasonic power was 65 W, the frequency was 35 kHz, the alcohol extraction temperature was 63 ° C, the time was 1.5 h, and after the alcohol extraction was completed, the alcohol extract was filtered to obtain the alcohol extract;

[0067] S5. Preparation of Houttuynia cordata extract: The water extract in step S3 and the alcohol extract in step S4 are mixed evenly, and then the solvent is removed by vacuum distillation at a pressure of 7 kPa to obtain the Houttuynia cordata extract.

[0068] Compared with Example 1, the present invention replaces the mixed acid with citric acid.

[0069] Comparative Example 2

[0070] A method for preparing a houttuynia cordata extract comprises the following steps:

[0071] S1. Pretreatment of Houttuynia cordata: Wash and dry the rhizomes of Houttuynia cordata, crush them into 100 mesh, add them into a mixed acid aqueous solution (malic acid concentration is 9 g / L, tartaric acid concentration is 4 g / L), the solid-liquid ratio of Houttuynia cordata rhizomes to the mixed acid aqueous solution is 1:13, and immerse them at 35°C for 2.5 hours to obtain a Houttuynia cordata mixed solution;

[0072] S2, enzymatic hydrolysis of complex enzymes: add 0.1 mol / L sodium hydroxide solution to the Houttuynia cordata mixed solution in step S1, adjust the pH to 4.5, then add pectinase (0.7% of the mass of Houttuynia cordata rhizome), enzymolysis at 48°C for 1.5 h, inactivate the enzyme in boiling water for 10 min after the enzymatic hydrolysis is completed, add 0.1 mol / L sodium hydroxide solution to adjust the pH to 6.5, add complex enzyme (cellulase and xylanase in a mass ratio of 6:4), the amount of complex enzyme added is 1.1% of the mass of Houttuynia cordata rhizome, enzymolysis at 43°C for 40 min, inactivate the enzyme in boiling water for 10 min after the enzymatic hydrolysis is completed, and obtain an enzymatic solution;

[0073] S3, preparation of aqueous extract: extract the enzymatic hydrolyzate in step S2 at 85°C for 1.5h, filter after the extraction to obtain aqueous extract and filter residue, and dry the filter residue for later use;

[0074] S4, preparation of alcohol extract: the filter residue in step S3 was added to ethanol, the solid-liquid ratio of the filter residue to ethanol was 1:10, followed by adding salicylic acid (0.25% of the filter residue mass) and diacetyl tartaric acid mono- and diglycerides (0.4% of the filter residue mass), and alcohol extraction was performed under ultrasonic conditions, the ultrasonic power was 65 W, the frequency was 35 kHz, the alcohol extraction temperature was 63 ° C, the time was 1.5 h, and after the alcohol extraction was completed, the alcohol extract was filtered to obtain the alcohol extract;

[0075] S5. Preparation of Houttuynia cordata extract: The water extract in step S3 and the alcohol extract in step S4 are mixed evenly, and then the solvent is removed by vacuum distillation at a pressure of 7 kPa to obtain the Houttuynia cordata extract.

[0076] Compared with Example 1, this comparative example did not add menthol during the water extraction process.

[0077] Comparative Example 3

[0078] A method for preparing a houttuynia cordata extract comprises the following steps:

[0079] S1. Pretreatment of Houttuynia cordata: Wash and dry the rhizomes of Houttuynia cordata, crush them into 100 mesh, add them into a mixed acid aqueous solution (malic acid concentration is 9 g / L, tartaric acid concentration is 4 g / L), the solid-liquid ratio of Houttuynia cordata rhizomes to the mixed acid aqueous solution is 1:13, and immerse them at 35°C for 2.5 hours to obtain a Houttuynia cordata mixed solution;

[0080] S2, enzymatic hydrolysis of complex enzymes: add 0.1 mol / L sodium hydroxide solution to the Houttuynia cordata mixed solution in step S1, adjust the pH to 4.5, then add pectinase (0.7% of the mass of Houttuynia cordata rhizome), enzymolysis at 48°C for 1.5 h, inactivate the enzyme in boiling water for 10 min after the enzymatic hydrolysis is completed, add 0.1 mol / L sodium hydroxide solution to adjust the pH to 6.5, add complex enzyme (cellulase and xylanase in a mass ratio of 6:4), the amount of complex enzyme added is 1.1% of the mass of Houttuynia cordata rhizome, enzymolysis at 43°C for 40 min, inactivate the enzyme in boiling water for 10 min after the enzymatic hydrolysis is completed, and obtain an enzymatic solution;

[0081] S3, preparation of aqueous extract: adding menthol (0.09% by mass of the aqueous extract) to the enzymatic hydrolysate in step S2, extracting with water at 85°C for 1.5h, filtering after the aqueous extraction to obtain an aqueous extract and a filter residue, and drying the filter residue for later use;

[0082] S4, preparation of alcohol extract: the filter residue in step S3 was added to ethanol, the solid-liquid ratio of the filter residue to ethanol was 1:10, and then salicylic acid (0.65% of the mass of the filter residue) was added, and alcohol extraction was performed under ultrasonic conditions, the ultrasonic power was 65W, the frequency was 35kHz, the alcohol extraction temperature was 63°C, and the time was 1.5h. After the alcohol extraction was completed, the mixture was filtered to obtain an alcohol extract;

[0083] S5. Preparation of Houttuynia cordata extract: The water extract in step S3 and the alcohol extract in step S4 are mixed evenly, and then the solvent is removed by vacuum distillation at a pressure of 7 kPa to obtain the Houttuynia cordata extract.

[0084] Compared with Example 1, in this comparative example, no diacetyl tartaric acid mono- and diglycerides were added during the alcohol extraction process.

[0085] Comparative Example 4

[0086] A method for preparing a houttuynia cordata extract comprises the following steps:

[0087] S1. Pretreatment of Houttuynia cordata: Wash and dry the rhizomes of Houttuynia cordata, crush them into 100 mesh, add them into a mixed acid aqueous solution (malic acid concentration is 9 g / L, tartaric acid concentration is 4 g / L), the solid-liquid ratio of Houttuynia cordata rhizomes to the mixed acid aqueous solution is 1:13, and immerse them at 35°C for 2.5 hours to obtain a Houttuynia cordata mixed solution;

[0088] S2, enzymatic hydrolysis of complex enzymes: add 0.1 mol / L sodium hydroxide solution to the Houttuynia cordata mixed solution in step S1, adjust the pH to 4.5, then add pectinase (0.7% of the mass of Houttuynia cordata rhizome), enzymolysis at 48°C for 1.5 h, inactivate the enzyme in boiling water for 10 min after the enzymatic hydrolysis is completed, add 0.1 mol / L sodium hydroxide solution to adjust the pH to 6.5, add complex enzyme (cellulase and xylanase in a mass ratio of 6:4), the amount of complex enzyme added is 1.1% of the mass of Houttuynia cordata rhizome, enzymolysis at 43°C for 40 min, inactivate the enzyme in boiling water for 10 min after the enzymatic hydrolysis is completed, and obtain an enzymatic solution;

[0089] S3, preparation of aqueous extract: adding menthol (0.09% by mass of the aqueous extract) to the enzymatic hydrolysate in step S2, extracting with water at 85°C for 1.5h, filtering after the aqueous extraction to obtain an aqueous extract and a filter residue, and drying the filter residue for later use;

[0090] S4, preparation of alcohol extract: the filter residue in step S3 was added to ethanol, the solid-liquid ratio of the filter residue to ethanol was 1:10, and then diacetyl tartaric acid mono- and diglycerides (0.65% of the mass of the filter residue) were added, and alcohol extraction was performed under ultrasonic conditions, the ultrasonic power was 65 W, the frequency was 35 kHz, the alcohol extraction temperature was 63 ° C, the time was 1.5 h, and after the alcohol extraction was completed, the alcohol extract was filtered to obtain the alcohol extract;

[0091] S5. Preparation of Houttuynia cordata extract: The water extract in step S3 and the alcohol extract in step S4 are mixed evenly, and then the solvent is removed by vacuum distillation at a pressure of 7 kPa to obtain the Houttuynia cordata extract.

[0092] Compared with Example 1, salicylic acid was not added during the alcohol extraction process in this comparative example.

[0093] For the preparation methods of Examples 1-4 and Comparative Examples 1-4, the polysaccharide yield and total flavonoid yield in the Houttuynia cordata extract were calculated. The polysaccharide content was determined by phenol-sulfuric acid colorimetry, where the polysaccharide yield / % = the mass of polysaccharides in the extract / the mass of Houttuynia cordata used × 100; the flavonoids were determined by ultraviolet spectrophotometry, where the flavonoid yield / % = the mass of flavonoids in the extract / the mass of Houttuynia cordata used × 100. At the same time, the antioxidant activity of the Houttuynia cordata extract was tested. The specific test method was as follows: 2.0 mL of a 0.2 mmol / L -1 The DPPH·ethanol solution was placed in a 10 mL test tube, and 2 mL of the Houttuynia cordata extract solution of Examples 1-4 and Comparative Examples 1-4 was added to a concentration of 5 mg·mL -1 , quickly mix, keep it in a 37℃ constant temperature water bath and avoid light, react for 30min, measure the absorbance A1, take 2mL ethanol and 2mL DPPH·ethanol (0.2mmoI·L -1) and mix well, measure the absorbance A0, and at the same time measure the absorbance A2 after mixing 2 mL of 95% ethanol with 2 mL of sample solution; DPPH clearance rate is calculated according to the following formula: DPPH clearance rate = , the test results are shown in Table 1.

[0094] Table 1

[0095]

[0096] As can be seen from Table 1 above, the preparation method of the Houttuynia cordata extract provided by the present invention effectively improves the yield of Houttuynia cordata polysaccharides and total flavonoids. At the same time, the prepared Houttuynia cordata extract has better antioxidant activity and has good application prospects.

[0097] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a Houttuynia cordata extract, characterized in that: The following steps are involved: S1. Crush the rhizomes of Houttuynia cordata and add them into a mixed acid aqueous solution for immersion to obtain a Houttuynia cordata mixed solution; S2, adjusting the pH of the Houttuynia cordata mixed solution to 4-5, adding pectinase, performing enzymatic hydrolysis once, inactivating the enzyme, adjusting the pH to 6-7, adding complex enzyme, performing enzymatic hydrolysis twice, inactivating the enzyme, and obtaining an enzymatic hydrolyzate; S3, adding menthol to the enzymatic hydrolyzate, extracting with water, and obtaining a water extract and a filter residue; S4, adding the filter residue to ethanol, followed by adding salicylic acid and diacetyl tartaric acid mono- and diglycerides, performing alcohol extraction under ultrasonic conditions, and filtering to obtain an alcohol extract; S5. Mixing the aqueous extract and the alcohol extract, and performing reduced pressure distillation to obtain a herb Houttuynia cordata extract; The mixed acid aqueous solution in step S1 is composed of malic acid, tartaric acid and water, the concentration of malic acid is 7-10g / L, and the concentration of tartaric acid is 3-5g / L; the complex enzyme in step S2 is composed of a mixture of cellulase and xylanase in a mass ratio of 5-7:3-5.

2. The preparation method according to claim 1, characterized in that The mesh size of the Houttuynia cordata powder after the pulverization in step S1 is 80-120 mesh, and the temperature of the immersion treatment is 30-40° C. and the time is 2-3 hours.

3. The preparation method according to claim 1, characterized in that In step S1, the material-liquid ratio of the houttuynia cordata rhizome to the mixed acid aqueous solution is 1:10-15.

4. The preparation method according to claim 1, characterized in that In step S2, the amount of pectinase added is 0.5-0.8% of the mass of the rhizome of Houttuynia cordata, the temperature of the first enzymatic hydrolysis is 45-50° C., and the time is 1-2 h.

5. The preparation method according to claim 1, characterized in that In step S2, the amount of the complex enzyme added is 1-1.2% of the mass of the rhizome of Houttuynia cordata, the temperature of the secondary enzymatic hydrolysis is 40-45° C., and the time is 30-50 min.

6. The preparation method according to claim 1, characterized in that In step S3, the amount of menthol added is 0.07-0.1% of the mass of the enzymatic hydrolysate, the water extraction temperature is 80-90° C., and the time is 1-2 h.

7. The preparation method according to claim 1, characterized in that In step S4, the material-liquid ratio of the filter residue to ethanol is 1:8-12, the amount of salicylic acid added is 0.2-0.3% of the mass of the filter residue, and the amount of diacetyl tartaric acid mono- and diglycerides added is 0.3-0.5% of the mass of the filter residue.

8. The preparation method according to claim 1, characterized in that The power of the ultrasound in step S4 is 60-70W, the frequency is 30-40kHz, the temperature of the alcohol extraction is 60-65°C, and the time is 1-2h.

9. The preparation method according to claim 1, characterized in that The pressure of the reduced pressure distillation in step S5 is 5-10 kPa.

10. A herba houttuyniae extract prepared by the method according to any one of claims 1 to 9.

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