阅读说明：本技术 一种酶法制备人参皂苷f1的方法及其应用 (Method for preparing ginsenoside F1 by using enzymatic method and application thereof ) 是由 周义发 范玉莹 原野 孟煜晗 胡晨星 李苇荔 于 2021-07-05 设计创作，主要内容包括：本发明涉及生物医学领域,提供了一种酶法制备人参皂苷F1的方法及其应用,所述方法直接采用糖苷水解酶BglSK水解糖基实现皂苷之间的转化,反应时间短,成本低,反应条件更温和,F1粗品中的副产物含量少,容易纯化,原料转化率、纯度和产率均有提升。同时制备得到的人参皂苷F1能够降低血脂含量,减少白色脂肪沉积,降低血糖,改善胰岛素抵抗,加速能量消耗,具有作为降血脂、降血糖和减肥药物的良好潜力。(The invention relates to the field of biomedicine, and provides a method for preparing ginsenoside F1 by an enzymatic method and application thereof, wherein the method directly adopts glycoside hydrolase BglSK to hydrolyze glycosyl so as to realize conversion between saponins, the reaction time is short, the cost is low, the reaction condition is milder, the content of byproducts in a F1 crude product is less, the purification is easy, and the conversion rate, the purity and the yield of raw materials are improved. Meanwhile, the prepared ginsenoside F1 can reduce the blood fat content, reduce white fat deposition, reduce blood sugar, improve insulin resistance and accelerate energy consumption, and has good potential as a medicament for reducing blood fat, reducing blood sugar and losing weight.)

1. A method for preparing ginsenoside F1 by an enzymatic method is characterized by comprising the following steps:

mixing triol group ginsenoside, glycoside hydrolase BglSK and buffer solution for hydrolysis, centrifuging the hydrolysate to obtain precipitate, removing protein from the precipitate, and purifying to obtain the ginsenoside F1.

2. The method of claim 1, wherein the buffer is 20mM Na₂HPO₄-NaH₂PO₄And (4) a buffer solution.

3. The method of claim 1, wherein the concentration of the triol set of ginsenosides is (15-25) mg/mL.

4. The method as claimed in claim 1, wherein the glycoside hydrolase BglSK is added in an amount of 2-4kU/g of starting material.

5. The method of claim 1, wherein the pH of the hydrolysis is 7-9 and the temperature of the hydrolysis is 30-40 ℃.

6. The method of claim 1, wherein the hydrolysis time is 2.5-4 days.

7. The method as claimed in claim 1, wherein the centrifugal force of the centrifugation is 4000-8000rcf and the time of the centrifugation is 10-30 min.

8. The method of claim 1, wherein the deproteinizing solvent is 80% -95% ethanol.

9. Use of ginsenoside F1 prepared by the method of any one of claims 1-8 in the preparation of a hypoglycemic or hypolipidemic agent.

10. Use of ginsenoside F1 prepared by the method of any one of claims 1-8 in preparing weight-reducing medicine.

Technical Field

The invention relates to the field of biomedicine, in particular to a method for preparing ginsenoside F1 by an enzyme method and application thereof.

Background

Obesity is a chronic metabolic disease, and refers to abnormal distribution of body fat and/or excessive accumulation and weight gain. Obesity is also a risk factor for the development of cardiovascular and cerebrovascular diseases, type II diabetes, osteoarthropathy, and the like. Obesity causes a series of complications or related diseases, affects the life span of humans, and causes a reduction in the quality of life of humans.

Obesity occurs because the body's caloric intake is greater than the consumption, resulting in excessive fat accumulation. Studies have demonstrated that adipose tissue in the body can be divided into two broad categories: white Adipose Tissue (WAT) distributed in subcutaneous, mesenteric, etc. regions and a small amount of Brown Adipose Tissue (BAT) present in the pericervical, interscapular, pericostal, etc. regions. Obesity is commonly referred to as being caused in the body by excessive accumulation of WAT; BAT is the major organ of non-shivering heat production under cold adaptation conditions, and can maintain the energy metabolism balance of the body by consuming energy and producing heat.

The pathogenesis of obesity is complex, and a good drug target point is not provided at present. In the development process of weight-reducing drugs, many drugs act by acting on the nerve feeding center, possibly with the side effects of depression and anxiety; at the same time, researchers are not well aware of the mechanisms of peripherally acting drugs in various tissues, and unexpected side effects such as the risk of immunogenicity of peptide hormone analogs may occur. However, from a new perspective, namely energy balance, the effect of losing weight by increasing the energy consumption of the body can become a new obesity treatment strategy, and a new direction is provided for the discovery of potential weight-losing drugs.

Ginseng (panaxginngcc.a.mey.) is a herbaceous plant of the genus panacis (Panax) of the family Araliaceae (Araliaceae), and is a famous and precious medicinal material produced in the northeast of China. Today, ginseng is one of the most widely used Chinese herbal medicines throughout the world. The ginseng contains various effective components including ginsenoside, ginseng polysaccharide, peptide, amino acid, trace elements, organic acid, etc., wherein the ginsenoside is the main active component of the ginseng and has the functions of resisting oxidation, aging, tumor and fatigue and improving the immunity of a human body. Ginsenoside is glycoside compound formed by connecting glycosyl with ginsenoside through glycosidic bond. The sugar chain composition has a close relationship with pharmacological activity. According to content, the ginsenoside can be divided into main ginsenoside (such as Rb1, Rb2, Rc, Rd, etc.) and rare ginsenoside (Rg3, Rh1, F1, CK, etc.), wherein ginsenoside F1 is triol type ginsenoside. Ginsenoside F1 is intestinal bacteria metabolite of ginsenoside Rg1 and notoginsenoside R1, has low content in natural medicinal materials, and is only separated from leaves and flowers of ginseng at present. The content of ginsenoside in Ginseng radix is 2-4%, the variety of saponin is more, and the variety has been identified to be more than 70. Ginsenoside F1 has strong pharmacological activity in many aspects: ginsenoside F1 is absorbed into the blood and can exert estrogenic effects therein; it also exhibits an anti-cancer effect, showing a strong inhibitory effect on the proliferation of B16 cells; it has anti-aging and anti-oxidation effects, and has competitive inhibition effect on the activity of CYP3A4, and has weaker inhibition effect on the activity of CYP2D 6; ginsenoside F1 also has good protective effect on keratinocyte.

Studies have shown that rare saponin content is very low or even absent in wild ginseng. And compared with glycosylated ginseng, the rare saponins have better pharmacological activity. But the preparation and production are limited due to the low content. The rare ginsenoside prepared by the enzyme method has specific selectivity and high efficiency conversion rate and yield, and is a potential method. Therefore, it is very necessary to prepare rare ginsenosides by selectively hydrolyzing glycosyl of the original ginsenosides by enzyme method.

CN105418718A discloses that a new compound 6' -malonic acid monomethyl acyl ginsenoside F1 is obtained by using ginseng flower as a raw material and carrying out methods of alcohol extraction, silica gel column chromatography, MCIGEL column chromatography and recrystallization. CN105601693A discloses that F1 is extracted from ginseng flowers, and the ginsenoside F1 monomer is obtained by organic solvent extraction, silica gel column chromatography and separation and purification. Application publication Nos. CN108623650A, CN108727457A and CN109021053A disclose that ginseng flower buds are used as raw materials, total extract is obtained by extraction with organic solvent, impurity removal and concentration are carried out by a combination method of macroporous resin and organic solvent, then high-speed countercurrent separation is carried out by organic solvent, and 6 '-acetyl ginsenoside F1, 6' -malonyl ginsenoside F1 and 3-acetyl ginsenoside F1 are respectively obtained by the same method of the three patents. These methods resulted in essentially the F1(F1 derivative) with a group, rather than the monomeric ginsenoside F1. At present, ginsenoside F1 is prepared from rare ginsenoside by enzyme conversion, and CN101012473 discloses ginsenoside F1 prepared by biotransformation technology, wherein the raw material is panaxatriol group saponin or ginsenoside Rg1 monomer to generate F1, and the selected strain is Penicillium planiculosum or Myrothecium verrucaria. CN105648021B discloses that triol saponins are respectively mixed with organic solvent and buffer solution to prepare substrate solution, and the substrate solution reacts with crude enzyme solution obtained by fermenting aspergillus microorganism to obtain rare ginsenoside F1. However, the patents of preparing F1 by biological methods are all prepared by bacterial or fungal fermentation, the preparation process is complex, the requirements on reaction conditions are high, the conversion rate of raw materials is low, the obtained byproducts are many, the purity of ginsenoside F1 is poor, and the yield is low. Therefore, it is necessary to provide a method for preparing ginsenoside F1 by an enzymatic method, thereby improving the conversion rate of raw materials and the purity and yield of products and reducing the by-products.

Disclosure of Invention

In view of the above, the present invention provides a method for preparing ginsenoside F1 by an enzymatic method, which can improve the conversion rate of raw materials, reduce the obtained byproducts, and improve the purity and yield of monomeric ginsenoside F1.

In order to solve the technical problems, the invention provides a method for preparing ginsenoside F1 by an enzyme method, which specifically comprises the following steps:

mixing triol group ginsenoside, glycoside hydrolase BglSK and buffer solution for hydrolysis, centrifuging the hydrolysate to obtain precipitate, removing protein from the precipitate, and purifying to obtain the ginsenoside F1.

Preferably, the buffer is 20mM Na₂HPO₄-NaH₂PO₄And (4) a buffer solution.

Preferably, the concentration of the triol group of ginsenosides is (15-25) mg/mL.

Preferably, the addition amount of the glycoside hydrolase BglSK is 2-4kU/g raw material.

Preferably, the pH of the hydrolysis is 7-9 and the temperature of the hydrolysis is 30-40 ℃.

Preferably, the hydrolysis time is 2.5-4 d.

Preferably, the centrifugal force of the centrifugation is 4000-8000rcf, and the time of the centrifugation is 10-30 min.

Preferably, the deproteinizing solvent is 80% -95% ethanol.

The invention also provides application of the ginsenoside F1 prepared by the method in preparing a medicine for reducing blood sugar or blood fat.

The invention also provides application of the ginsenoside F1 prepared by the method in preparing weight-reducing medicines.

The invention provides a method for preparing ginsenoside F1 by an enzyme method, which directly adopts glycoside hydrolase BglSK to hydrolyze glycosyl so as to realize conversion between saponins, has short reaction time, low cost, milder reaction condition, less by-product content in FI crude product and easy purification, and can obviously improve the conversion rate of raw materials for preparing ginsenoside F1 and the purity and yield of ginsenoside F1. Meanwhile, the prepared ginsenoside F1 can reduce the blood fat content, reduce white fat deposition, reduce blood sugar, improve insulin resistance and accelerate energy consumption, and has good potential as a medicament for reducing blood fat, reducing blood sugar and losing weight.

Drawings

Fig. 1 shows the effect of different concentrations of notoginseng triol saponin on the conversion rate of Rg 1; wherein the abscissa is the concentration of the notoginseng triol saponin, and the ordinate is the conversion rate of Rg 1.

FIG. 2 shows the effect of different enzyme addition amounts and hydrolysis times on the conversion of Rg 1; wherein the abscissa is hydrolysis time, and the ordinate is Rg1 conversion rate.

Fig. 3 is a graph of the effect of different pH on Rg1 conversion; wherein the abscissa is pH and the ordinate is Rg1 conversion.

Fig. 4 is a graph of the effect of different hydrolysis temperatures on Rg1 conversion; wherein the abscissa is the hydrolysis temperature and the ordinate is the conversion rate of Rg 1.

FIG. 5 is the electrophoresis chart of purified BglSK enzyme; wherein, 1 is BglSK enzyme before induction; 2 is induced BglSK enzyme; and 3 is purified BglSK enzyme.

FIG. 6 is a high performance liquid chromatogram of different compositions; wherein A is the chromatogram of a reference substance of ginsenoside F1; b is chromatogram of raw material of notoginseng triol group saponin; c is a chromatogram of a crude product of ginsenoside F1; d is the chromatogram of purified ginsenoside F1.

FIG. 7 is a graph showing the effect of ginsenoside F1 on mouse energy metabolism; wherein A-B is the influence of ginsenoside F1 on mouse heat production; C-D is the influence of ginsenoside F1 on oxygen intake of mice; E-F is the effect of ginsenoside F1 on the carbon dioxide production of mice.

Detailed Description

The invention provides a method for preparing ginsenoside F1 by an enzyme method, which specifically comprises the following steps:

mixing triol group ginsenoside, glycoside hydrolase BglSK and buffer solution for hydrolysis, centrifuging the hydrolysate to obtain precipitate, removing protein from the precipitate, and purifying to obtain the ginsenoside F1. In the invention, the glycoside hydrolase BglSK can specifically hydrolyze C-6 glycosyl of ginsenoside Rg1, so that the ginsenoside F1 is prepared by the following specific principle:

in the invention, the triol group ginsenoside is preferably pseudo-ginseng triol group saponin. The source of the panaxtriol saponins is not particularly limited in the invention, and the panaxtriol saponins can be obtained by adopting conventional commercial products in the field. In a specific embodiment of the present invention, the notoginseng triol saponin is obtained from Ningbo jin einong Biotechnology Ltd, wherein the content of Rg1 is 54.3%. In the present invention, the concentration of the triol ginsenoside is preferably (15-25) mg/mL.

In order to determine the concentration of the panaxatriol saponins, the influence of the concentration of different panaxatriol saponins on the conversion rate of Rg1 is determined on the basis of determination of other raw materials and experimental conditions, and the method comprises the following specific steps:

1) preparation of 50mL reaction system: is prepared from panaxtriol saponins, 5kU glycoside hydrolase BglSK, pH8.0, and 20mM Na₂HPO₄-NaH₂PO₄Buffer solution; wherein, the addition amounts of the notoginseng triol group saponin are respectively set as 0.75g, 1g, 1.25g, 1.5g and 1.75g, and the corresponding concentrations are respectively 15mg/mL, 20mg/mL, 25mg/mL, 30mg/mL and 35 mg/mL;

2) placing the reaction system in a 35 ℃ constant temperature shaking table, and reacting for 7d at 170 rpm;

3) after the reaction is finished, taking 200uL of reaction liquid, freeze-drying, adding 1mL of methanol for redissolving, centrifuging at 6000rcf for 5min, filtering by using a 0.22 mu m organic filter membrane, taking 10 mu L of sample injection for high performance liquid detection, and calculating the conversion rate of Rg1, wherein the detection result is shown in figure 1.

As shown in the attached figure 1, when the concentration of the raw materials is (15-25) mg/mL, the conversion rate of Rg1 in the reaction liquid at 7d is over 95%, and when the concentration is further improved, the conversion rate of Rg1 at 7d is still lower than 70%.

In the present invention, the buffer is preferably Na₂HPO₄-NaH₂PO₄Buffer solution of said Na₂HPO₄-NaH₂PO₄The concentration of the buffer is preferably 10 to 100mM, more preferably 20 mM. In the invention, the addition amount of the glycoside hydrolase BglSK is preferably 2-4kU/g of raw material, and more preferably 3kU/g of raw material. The source of the glycoside hydrolase BglSK is not particularly limited in the present invention, and in the specific embodiment of the present invention, the glycoside hydrolase BglSK is preferably obtained by recombinant production. In the present invention, the pH of the hydrolysis is preferably 7 to 9, more preferably 8; the temperature of the hydrolysis is preferably 30-40 ℃, and more preferably 35 ℃; the hydrolysis time is preferably 2.5-4d, more preferably 3 d.

In order to determine the adding amount and hydrolysis time of the glycoside hydrolase BglSK, the influence of the adding amount or hydrolysis time of different glycoside hydrolase BglSK on the conversion rate of Rg1 is determined on the basis of determination of other raw materials and experimental conditions, and the specific steps are as follows:

1) preparation of 50mL reaction system: is prepared from 1.25g of panaxtriol saponins, glycoside hydrolase BglSK, pH8.0, and 20mM Na₂HPO₄-NaH₂PO₄Buffer solution; wherein the addition amounts of the glycoside hydrolase BglSK are respectively 1.25kU, 2.5kU, 3.75kU and 5kU, and the addition amounts of the recombinase corresponding to each gram of raw material are respectively 1kU, 2kU, 3kU and 4 kU;

2) placing the reaction system in a 35 ℃ constant temperature shaking table, reacting at 170rpm for 1d, 2d, 3d, 4d and 5d respectively;

3) after the reaction is finished, taking 200uL of reaction liquid, freeze-drying, adding 1mL of methanol for redissolving, centrifuging at 6000rcf for 5min, filtering by using a 0.22 mu m organic filter membrane, taking 10 mu L of sample injection for high performance liquid detection, and calculating the conversion rate of Rg1, wherein the detection result is shown in figure 2.

As shown in the attached figure 2, the reaction time 3d is favorable for improving the conversion rate of Rg1 by adding 3kU of glycoside hydrolase BglSK per gram of raw material; decreasing the amount of enzyme will decrease the conversion of Rg1, while increasing the amount of enzyme will not further increase the conversion but will increase the cost.

In order to determine the pH of hydrolysis, the influence of different pH values on the conversion rate of Rg1 is determined on the basis of determination of raw materials and experimental conditions, and the specific steps are as follows:

1) preparation of 50mL reaction system: consists of 0.5g of notoginseng triol saponin, 2kU of glycoside hydrolase BglSK and buffer solution; wherein the buffer solution is pH5.0, 20mM NaAc-H Ac buffer solution, pH6.0, 20mM Na₂HPO₄-NaH₂PO₄Buffer, pH7.0, 20mM Na₂HPO₄-NaH₂PO₄Buffer, pH8.0, 20mM Na₂HPO₄-NaH₂PO₄Buffer, pH9.0, 20mM Glycine-NaOH buffer;

2) placing the reaction system in a constant temperature shaking table at 37 ℃ and reacting for 1d at 170 rpm;

3) after the reaction is finished, taking 200uL of reaction liquid, freeze-drying, adding 1mL of methanol for redissolving, centrifuging at 6000rcf for 5min, filtering by using a 0.22 mu m organic filter membrane, taking 10 mu L of sample injection for high performance liquid detection, and calculating the conversion rate of Rg1, wherein the detection result is shown in figure 3.

As can be seen from the attached figure 3, the conversion rate of the ginsenoside Rg1 by the glycoside hydrolase BglSK is the highest when the pH value is 8.0.

In order to determine the hydrolysis temperature, the influence of different temperatures on the conversion rate of the Rg1 is determined on the basis of determination of raw materials and experimental conditions, and the specific steps are as follows:

1) preparation of 50mL reaction system: consists of 0.5g of notoginseng triol saponin, 2kU of glycoside hydrolase BglSK, pH8.0, 20mM Na₂HPO₄-NaH₂PO₄Buffer solution;

2) placing the reaction system in a constant temperature shaking table, and reacting for 24h at 170rpm, wherein the reaction temperature is respectively 25 ℃, 30 ℃, 35 ℃, 40 ℃ and 45 ℃;

3) after the reaction is finished, taking 200 mu L of reaction liquid, freeze-drying, adding 1mL of methanol for redissolving, centrifuging at 6000rcf for 5min, filtering by using a 0.22 mu m organic filter membrane, taking 10 mu L of sample injection for high performance liquid detection, and calculating the conversion rate of Rg1, wherein the detection result is shown in figure 4.

As can be seen from the attached figure 4, the conversion rate of the ginsenoside Rg1 by the glycoside hydrolase BglSK is the highest when the hydrolysis temperature is 35 ℃.

In the invention, the hydrolysate is centrifuged to obtain a precipitate, the centrifugal force of the centrifugation is preferably 4000-8000rcf, more preferably 6000rcf, and the time of the centrifugation is preferably 10-30min, more preferably 15 min.

In the invention, the solvent for removing protein is preferably 80-95% ethanol. The protein removing method comprises the following steps: adding 80-95% ethanol into the precipitate, heating and stirring for the first time under the condition of condensation and reflux, and centrifuging to obtain a supernatant and a precipitate 1; adding 80-95% ethanol into the obtained precipitate 1, heating and stirring twice under reflux, centrifuging to obtain supernatant, mixing the two supernatants, and drying to obtain crude product of ginsenoside F1.

In the present invention, the mass-to-volume ratio of the precipitate to the ethanol in one heating and stirring is preferably 1g: 5mL-1 g: 20mL, more preferably 1g:10 mL; when the mixture is heated and stirred for the second time, the mass-to-volume ratio of the precipitate 1 to the ethanol is preferably 1g: 5mL-1 g: 20mL, more preferably 1g:5 mL. In the present invention, the heating temperature is preferably 55 to 65 ℃, more preferably 60 ℃; the heating time is preferably 0.5 to 1.5h, more preferably 1 h. In the present invention, the centrifugal force of the centrifugation is preferably 5500-6500rcf, more preferably 6000rcf, and the time of the centrifugation is preferably 13-20min, more preferably 15 min. The drying method of the present invention is not particularly limited, and a drying method that is conventional in the art may be employed.

The ginsenoside F1 is obtained by purifying the ginsenoside F1 crude product. In the present invention, the purification method is not particularly limited, and in the specific examples of the present invention, the purification method is preferably silica gel column chromatography. In the invention, the purity of the purified ginsenoside F1 is more than 95%.

The invention also provides application of the ginsenoside F1 prepared by the method in preparing a medicine for reducing blood sugar or blood fat.

The invention also provides application of the ginsenoside F1 prepared by the method in preparing weight-reducing medicines.

In a specific embodiment of the invention, sources of orlistat, mouse and ginsenoside PPT are as follows:

orlistat (Orlistat): (iii) Aladdin, O159936;

obese mice (B6/JGpt-Lep)^em1Cd25/Gpt, abbreviated ob/ob): jiangsu Jiejiaokang Biotech Co., Ltd., T001461;

normal mice (C57BL/6JGpt, abbreviated C57 BL/6J): jiangsu Jiejiaokang Biotech limited, N000013;

ginsenoside PPT: oddment biotechnology limited, a 0249; the structural formula of the ginsenoside PPT is shown as a formula I:

the present invention will be described in further detail with reference to some examples. The experimental procedures in the following examples are conventional unless otherwise specified. Materials, reagents, instruments and the like used in the following examples are commercially available unless otherwise specified. The quantitative tests in the following examples, all set up three replicates and the results averaged.

Example 1 preparation of glycoside hydrolase BglSK

(first) construction of recombinant vector

Artificially synthesizing a DNA molecule (namely, a glucoside hydrolase coding gene which is marked as a BglSK gene and has a fragment size of 1857bp) shown in a sequence table (with a GenBank login number of ACZ20402.1), taking the DNA molecule as a template, and performing amplification by using a primer forward primer: 5' -GGTTCCGCGTGGATCCCCCACTCCCCTGACCACCCTGACC-3' (recognition sequence for restriction enzyme BamHI is underlined) and reverse primer: 5' -GATGCGGCCGCTCGAGTCAGATGCTCAGCCCGTGCCCCAC-3' (recognition sequence of restriction enzyme XhoI is underlined) was subjected to PCR amplification to obtain a PCR product.

Carrying out double enzyme digestion on the obtained PCR product by using BamHI and XhoI, connecting the obtained enzyme digested fragment with a vector skeleton obtained by carrying out double enzyme digestion on PGEX-4T-1 by using BamHI and XhoI to obtain a recombinant vector, and marking the obtained recombinant vector with a correct sequence as PGEX-4T-1-BglSK.

Preparation of (II) BglSK enzyme

The obtained PGEX-4T-1-BglSK is introduced into Escherichia coli BL21(DE3) to obtain a recombinant bacterium, which is marked as BL 21-PGEX-4T-1-BglSK. BL21-PGEX-4T-1-BglSK was inoculated into LB medium containing kanamycin, cultured at 37 ℃ until the culture reached an OD600 of 0.6, isopropyl-. beta. -D-thiogalactopyranoside (IPTG) at a concentration of 0.1mM in the culture system was added to the culture system, the culture system was cultured at 25 ℃ for 24 hours to induce protein expression, and after completion of the culture, the culture system was centrifuged at 6000rcf for 15min at 4 ℃ to collect cells.

The obtained cells were washed twice with 100mM phosphate buffer (pH 7.0), and then suspended in this buffer to obtain a cell suspension. Subjecting the obtained thallus suspension to cell disruption by ultrasonication to obtain disrupted product, centrifuging the disrupted product at 26000rcf4 deg.C for 30min, and collecting supernatant to obtain crude cell extract. The crude cell extract obtained is used to obtain purified alpha-L-rhamnosidase. Electrophoresis detection As shown in FIG. 5, the purity of the purified BglSK is high and the size of the band is correct.

Enzyme activity detection of (tri) glycoside hydrolase BglSK

1. Preparing a reaction system: the reaction system was 100. mu.L, and 10. mu.L of a sample to be tested (a dilution of purified glycoside hydrolase (diluted 5-fold with ultrapure water) or a dilution of IPTG-induced total protein solution (diluted 5-fold with ultrapure water), 10. mu.L of an aqueous solution of pNP-. beta. -D-Glu (a product of Sigma Co.) having a concentration of 5mM, and 80. mu. LpH 8.0.0 and 25mM Na were added to the reaction system₂HPO₄-NaH₂PO₄And (4) buffer solution.

2. And (3) placing the system prepared in the step (1) at 35 ℃ and reacting for 10 min.

3. After completing step 2, 100. mu.L of 0.5M NaOH aqueous solution was added to terminate the reaction, and then 6000rcf was centrifuged for 10min, and the supernatant was collected and filtered through 0.45 μ M organic filter membrane, and the filtrate was collected.

4. After the step 3 is finished, detecting the light absorption value of the filtrate at 405 nm; and obtaining the enzyme activity of the glycoside hydrolase of the sample to be detected according to the pNP standard curve. Further obtaining the enzyme activity of the total protein solution after the induction of the purified glycoside hydrolase BglSK and IPTG.

5. And respectively measuring the total protein content of the total protein solution after the induction of the purified glycoside hydrolase BglSK and IPTG by using a Coomassie brilliant blue G250 method, and further obtaining the specific activity of the total protein solution after the induction of the purified glycoside hydrolase BglSK and IPTG.

The result shows that the specific activity of the total protein solution after IPTG induction is 12U/mg, the specific activity of the purified glycoside hydrolase BglSK is 35U/mg, and the glycoside hydrolase BglSK has the activity of glycoside hydrolase.

The enzyme activity unit (U) of the glycoside hydrolase BglSK is defined as: the enzyme amount required for catalyzing p-Nitrophenyl alpha-L-glucoside (pNP-beta-D-Glu) to generate 1 mu mol of pNP per minute at 35 ℃ is 1U.

Example 2

The method for preparing the ginsenoside F1 comprises the following steps:

1. hydrolysis: 500mL of 20mM phosphate buffer solution with pH8.0 was added to a 2L Erlenmeyer flask, 25g of notoginseng triol saponin (Ningbo Jinianong Biotech Co., Ltd., Rg1 content of 54.3%) was added, 80kU of glycoside hydrolase BglSK was added, and the buffer solution was added to make up the system to 1L. The flask was placed in a constant temperature shaker and reacted at 35 ℃ for 72h at 170 rpm.

2. Centrifuging: transferring the reaction solution into a centrifuge cup, centrifuging at 6000rcf and 25 ℃ for 15min, discarding the supernatant, and collecting the precipitate.

3. Removing protein: adding 250mL of 95% ethanol into the precipitate, stirring uniformly, heating at 60 ℃ for 1h, centrifuging for 15min (6000rcf, 25 ℃), collecting the supernatant, adding 125mL of 95% ethanol into the precipitate, stirring uniformly at 25 ℃, centrifuging, collecting the supernatant, and combining the supernatants. And (3) concentrating the supernatant to be solid or powder by using a rotary evaporator under reduced pressure, and finally drying in a vacuum drying oven to obtain a ginsenoside F1 crude product.

4. And (3) purification: purifying the crude ginsenoside F1 by using a silica gel column, using normal phase silica gel powder (200 meshes and 300 meshes), wherein the mass of the silica gel is 400g, the specification of a glass column is 8 multiplied by 24cm, isocratic elution is adopted, and the mobile phase is methanol: ethanol: ethyl acetate ═ 3: 7: 60 (volume ratio), carrying out wet-process sample loading at the flow rate of 16mL/min, collecting effluent liquid by using a glass test tube, collecting 15mL of effluent liquid in each part, detecting a collecting solution by TLC (thin layer chromatography), combining the collecting solutions with a detection result of pure F1, and drying to obtain the ginsenoside F1.

Example 3

The panaxatriol saponins, the crude ginsenoside F1 and the pure F1 in example 2 are detected by high performance liquid chromatography, and the F1 content is calculated by comparing the peak areas of a sample to be detected and a standard F1.

The chromatographic conditions were as follows:

l-3000 high performance liquid chromatography system (available from Puyuan Seiko electro-technology, Inc.) using a C18 reverse phase column (4.6 mm. times.250 mm, 5 m). Linear gradient eluting with acetonitrile-water solution as eluent for 0-10min, 22.5% acetonitrile; 10-40min, 22.5% -70% acetonitrile; 40-50min, 100% acetonitrile. Sample loading amount: 200g, column temperature: 30 ℃, flow rate: 0.8mL/min, detector: UV-VIS detector, and absorbance at 203 nm.

In the embodiment, the ginsenoside F1 standard substance is a product of China pharmaceutical biological product institute, and the content of F1 is 93.5%. The high performance liquid chromatogram of the panaxtriol saponins, the crude product of ginsenoside F1 and the pure product of ginsenoside F1 are shown in figures 6B-D respectively. The calculated content and yield of ginsenoside F1 are shown in table 1 below.

TABLE 1 ginsenoside F1 content and yield

As can be seen from fig. 6C, during the transformation, Rg1 is completely transformed, a large amount of F1 and a small amount of Rh1 are generated, a small amount of Re is transformed into Rg2, the transformed product mainly consists of F1, and at the same time contains a small amount of Re, Rg2 and Rg1, and the composition of the transformed product (crude ginsenoside F1) is shown in table 2 below:

TABLE 2 crude composition of ginsenoside F1

Example 4

Comparing the method for preparing ginsenoside F1 of the present invention described in example 2 with the existing method for preparing ginsenoside F1 (wherein, method 1 refers to "study on immobilized β -glucosidase for preparing ginsenoside F1", zhangqi et al, china journal of antibiotics, 2012,37(001): 49-55. method 2 refers to "study on panaxatriol saponin hydrolase", xu shuang, university of Dalian industries, 2012. method 3 refers to "study on biotransformation method for preparing ginsenoside F1 and Rh 1", Wangyu, university of Dalian industries. method 4 refers to "study on oriented conversion of ginsenoside Rg1 to ginsenoside F1 by fungi EST-I and EST-II", Wuxili et al, university of Shenyang pharmacy, 2008 "), statistical analysis results in the following table 3:

TABLE 3 comparison of different methods for preparing ginsenoside F1

Example 5

Dissolving the ginsenoside F1 of example 2 in DMSO to prepare a 4mg/mL ginsenoside F1 stock solution; dissolving ginsenoside PPT in DMSO to obtain 4mg/mL ginsenoside PPT stock solution; orlistat is dissolved in H₂Preparing 4mg/mL orlistat stock solution in O; storing at room temperature.

8 male C57BL/6J mice at 4 weeks of age were used as group 1 and were not treated with the drug. 40 male ob/ob mice with the age of 4 weeks are selected and divided into 5 groups of 8 mice, and the following treatments are respectively carried out: group 2, no treatment with drug administration, was a blank control group; group 3, 5% DMSO was injected intraperitoneally for 5 weeks in equal volume in succession as a negative control; group 4, Orlistat (Orlistat) was injected intraperitoneally at a dose of 20mg/kg/d for 5 consecutive weeks as a positive control; group 5, ginsenoside F1 of example 2 was administered by intraperitoneal injection at a dose of 20mg/kg/d for 5 weeks; group 6, ginsenoside PPT was administered by intraperitoneal injection at a dose of 20mg/kg/d for 5 weeks. Each mouse of the administration group was administered 1 time per day. Wherein DMSO is dissolved in dH₂In O, a DMSO concentration of 5% (1mLDMSO/9 mLdH) was obtained₂O) solution, recorded as 5% DMSO.

Fasting plasma glucose was measured with a glucometer (neonatal ultra easy) 9 am after grouping before administration, and then weighed. Fasting glucose was monitored once a week from the start of dosing, fixed for detection with a glucometer (neonatal ultra easy) at 9 am, and mouse body weight was monitored once a week. After the administration, blood was collected from the mouse eyeball, and serum INS (Insulin), TG (Triglyceride), NEFA (Non-esterified fatty acid), and TC (Total cholesterol) contents were measured. After completion of the 5 week dosing, mice were sacrificed and gonadal white fat (gWAT) and inguinal white fat (iWAT) were removed and weighed.

The detection of the contents of INS, TG, NEFA and TC in serum is carried out by adopting an insulin Kit (Mouse INS Elisa Kit) (product number YX-091419M) of IBL company and a triglyceride Kit (TG, A110-1-1), a free fatty acid Kit (NEFA, A042-2-1) and a total cholesterol Kit (TC, A111-1) of Nanjing institute of Biotechnology.

Calculating the weight reduction rate and the fasting blood glucose reduction rate:

the weight loss rate is the change in body weight of mice in the drug-treated group/the change in body weight of mice in the non-administered group × 100%, and the change in body weight is the body weight after the 5 th week administration — the body weight before administration;

the fasting blood glucose lowering rate (blood glucose of mice after administration-blood glucose of mice before administration after grouping)/blood glucose of mice before administration after grouping × 100%.

ANOVA-one way statistical analysis was performed using SPSS statistical software, and the results of each index after completion of the 5 th week administration are shown in Table 4.

TABLE 4 Effect of ginsenoside F1 on the metabolic indices of obese mice

In Table 4, the results are expressed as mean. + -. SD; significance analysis results compared to group 3: p < 0.05; **: p <0.01, x: p < 0.001.

Wherein C57BL/6J is group 1, i.e., C57BL/6J no drug treatment group; ob/ob is group 2, i.e., ob/ob gives no drug treatment blank control group; ob + DMSO is group 3, i.e., ob/ob negative control group; ob + Orlistat is group 4, namely ob/ob Orlistat processing group; ob + F1 is group 5, i.e., ob/ob ginsenoside F1 treated group; ob + PPT is group 6, i.e., ob/ob ginsenoside PPT treated group.

As can be seen from Table 4 above, for ob/ob mice, the index changes are as follows:

(1) from the analysis of the body weight loss rate, the body weight of the mice after the administration of ginsenoside F1 increased very slowly compared to the group 3 mice, and the body weight loss rate was 29.33%. From the white fat gravimetric analysis, the weight of both gWAT and iWAT was significantly reduced in mice after ginsenoside F1 administration compared to group 3 mice, while there was no significant change in both gWAT and iWAT weight in mice after Orlistat administration, indicating that ginsenoside F1 can significantly reduce the weight of mice and white fat weight.

(2) From the analysis of the blood sugar reduction rate, compared with the group 3 mice, the blood sugar of the mice is remarkably reduced after the ginsenoside F1 is administrated, the reduction rate is 46.65%, while the blood sugar reduction rate of the mice after Orlistat is only 32.23%, which shows that the ginsenoside F1 has remarkable effect in reducing the blood sugar.

(3) From the analysis of insulin content, compared with the group 3 mice, the serum insulin content of the mice is remarkably reduced to 84.10mIU/L after the ginsenoside F1 is administrated, which shows that the ginsenoside F1 can improve the insulin resistance.

(4) From the analysis of blood lipid content, compared with the group 3 mice, the serum TG and NEFA levels of the mice are obviously reduced after the ginsenoside F1 is administrated, and the TC content is not obviously changed, which indicates that the ginsenoside F1 also has the function of reducing blood lipid.

Therefore, the ginsenoside F1 injected into the abdominal cavity can reduce the weight of an obese mouse, reduce the blood fat content, reduce white fat deposition, reduce blood sugar and improve insulin resistance, namely the ginsenoside F1 has the functions of reducing blood sugar and blood fat and has the potential of being used as a medicine for reducing blood sugar, blood fat or losing weight. The ginsenoside PPT can not reduce the weight of obese mice and the blood fat content, and the blood sugar level has no obvious change.

Example 6

The same administration method as that in example 4 is adopted, and after 5 weeks of administration, indices such as oxygen consumption, activity and the like of the mice are detected by a metabolism cage-CLAMS laboratory animal detection system (Columbus, USA), wherein the CLAMS laboratory animal detection system can eliminate the influence of the activity factor on the metabolic rate of the bodies of the laboratory mice. Mice were housed in a single cage for 1 week before they were placed in a metabolism cage, and were allowed to acclimate for 24 hours after the placement in the metabolism cage, after which the oxygen consumption (V) was recorded for 24 hoursO₂)、CO₂Expired Volume (VCO)₂) Activity (xAMB) and HEAT generation rate (HEAT). The results of the experiments were analyzed and plotted using GraphPad Prism 6.0 or excel 2010 software, and are shown in fig. 7.

As can be seen from the results in FIG. 7, the heat production of the mice in the ginsenoside F1-treated group was significantly higher than that of the mice in the group 3 (i.e., the negative control group) (A in FIG. 7) at each test time point, and the statistical analysis of the diurnal difference in heat production of the two groups of mice was statistically significant (B in FIG. 7). The results of the CLAMS animal test system show that the oxygen consumption and carbon dioxide exhalation of the ob/ob mice of the ginsenoside F1 treatment group are higher than those of the mice of the group 3 (namely, a negative control group), and the difference has statistical significance (figures 7C-F). The ginsenoside F1 prepared by the method can increase the metabolic rate of experimental mice. The obesity is caused by the fact that the intake of energy is larger than the output, the metabolic rate is increased, the energy can be more dissipated in a heat energy mode under the same state, and the body weight is further reduced, so that the ginsenoside F1 has the effect of accelerating energy consumption and can be used as an active ingredient of a weight-losing medicine.

The above examples show that the enzymatic method for preparing ginsenoside F1 of the present invention directly adopts glycoside hydrolase BglSK to hydrolyze glycosyl to achieve conversion between saponins, has the advantages of short reaction time, low cost, mild reaction conditions, low content of by-products in crude F1, easy purification, and capability of significantly improving the conversion rate of raw materials for preparing ginsenoside F1, and the purity and yield of ginsenoside F1. Meanwhile, the prepared ginsenoside F1 can reduce the blood fat content, reduce white fat deposition, reduce blood sugar, improve insulin resistance and accelerate energy consumption, and has good potential as a medicament for reducing blood fat, reducing blood sugar and losing weight.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by the present specification, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.