COMPOSITION FOR INHIBITING ALPHA-GLUCOSIDASE AND APPLICATION THEREOF

Abstract

The present invention discloses a composition for inhibiting α-glucosidase and application thereof, and belongs to the technical field of natural active compounds. The composition of the present invention contains daidzein and quercetin derivatives, and the quercetin derivative is taxifolin or 3-O-methyl quercetin, where the mass ratio of the daidzein to the taxifolin is 8:25-10:25; and the mass ratio of the daidzein to the 3-O-methyl quercetin is 8:2-8:4. The composition of the present invention has an obvious synergistic effect of inhibiting α-glucosidase, and the effect thereof is better than that of using the flavonoid compound alone, and may reduce a dosage of the use of drugs and occurrence of drug resistance.

Claims

1. A composition, containing daidzein and quercetin derivatives, wherein the quercetin derivative is taxifolin or 3-O-methyl quercetin, wherein the mass ratio of the daidzein to the taxifolin is 8:25-10:25; and the mass ratio of the daidzein to the 3-O-methyl quercetin is 8:2-8:4.

2. Application of the composition in the preparation of a formulation having an effect of inhibiting α-glucosidase according to claim 1.

3. An α-glucosidase inhibitor, wherein effective components thereof contain daidzein and taxifolin, or daidzein and 3-O-methyl quercetin, wherein the mass ratio of the daidzein to the taxifolin is 8:25-10:25; and the mass ratio of the daidzein to the 3-O-methyl quercetin is 8:2-8:4.

4. Application of the composition in the preparation of a drug having a hypoglycemic effect according to claim 1.

5. The application according to claim 4, wherein the hypoglycemic effect is to block digestion and absorption of carbohydrates by inhibiting activity of α-glucosidase to achieve a purpose of controlling postprandial hyperglycemia.

6. A medicine having a hypoglycemic effect, wherein effective components thereof contain daidzein and taxifolin, or daidzein and 3-O-methyl quercetin, wherein the mass ratio of the daidzein to the taxifolin is 8:25-10:25; and the mass ratio of the daidzein to the 3-O-methyl quercetin is 8:2-8:4.

7. The drug according to claim 6, wherein the drug contains a carrier, a solvent, a diluent, an excipient, or other mediums acceptable in pharmacy.

8. The drug according to claim 6, wherein a dosage form of the drug is selected from powder, granules, capsules, injection, oral liquid, or tablets.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0019] FIG. 1 is an inhibitory activity of daidzein compositions of Example 1 and Example 5 on α-glucosidase;

[0020] FIG. 2 is an inhibition curve graph of α-glucosidase by a daidzein+taxifolin (8:25) composition;

[0021] FIG. 3 is a Fa-CI trend graph of α-glucosidase by a daidzein+taxifolin (8:25) composition;

[0022] FIG. 4 is an inhibition curve graph of α-glucosidase by a daidzein+3-O-methyl quercetin (8:2) composition;

[0023] FIG. 5 is a Fa-CI trend graph for inhibition of α-glucosidase by a daidzein+3-O-methyl quercetin (8:2) composition;

[0024] FIG. 6 is an inhibitory activity of daidzein compositions of Example 2 and Example 6 on α-glucosidase;

[0025] FIG. 7 is an inhibition curve graph of α-glucosidase by a daidzein+taxifolin (8:30) composition;

[0026] FIG. 8 is an inhibition curve graph of α-glucosidase by a daidzein+3-O-methyl quercetin (8:4) composition;

[0027] FIG. 9 is an inhibitory activity of daidzein compositions of Example 3 and Example 7 on α-glucosidase;

[0028] FIG. 10 is an inhibition curve graph of α-glucosidase by a daidzein+taxifolin (8:50) composition;

[0029] FIG. 11 is an inhibition curve graph of α-glucosidase by a daidzein+3-O-methyl quercetin (8:6) composition;

[0030] FIG. 12 is an inhibitory activity of daidzein compositions of Example 4 and Example 8 on α-glucosidase;

[0031] FIG. 13 is an inhibition curve graph of α-glucosidase by a daidzein+taxifolin (10:25) composition; and

[0032] FIG. 14 is an inhibition curve graph of α-glucosidase by a daidzein+3-O-methyl quercetin (10:2) composition;

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The terms used in the present invention, unless otherwise specified, generally have meanings normally understood by those of ordinary skills in the art.

[0034] Daidzein, molecular formula is C15H10O4; molecular weight is: 254.24; and CAS accession number is: 486-66-8, and structural formula is:

##STR00001##

[0035] Taxifolin, molecular formula is C15H12O7; molecular weight is: 304.25; and CAS accession number is: 480-18-2, and structural formula is:

##STR00002##

[0036] 3-O-Methyl Quercetin, molecular formula is C16H12O7; molecular weight is: 316.26; and CAS accession number is: 1486-70-0, and structural formula is:

##STR00003##

[0037] α-glucosidase (coming from Saccharomyces cerevisiae, Sigma);

[0038] 4-nitrophenyl-α-D-glucopyranoside (pNPG, TOKYO Chemica Industry Co., LTD);

[0039] acarbose (Acarbose, TOKYO Chemica Industry Co., LTD);

[0040] daidzein, taxifolin, and 3-O-methyl quercetin (Solarbio, Beijing);

[0041] Millipore Simplicity water purification system (Millipore, France);

[0042] sodium phosphate salt buffer solution (pH 6.8, 0.1 mol L−1); and

[0043] enzyme-linked analyzer TECAN infinite M200 PRO (Teacan Group Ltd., Switzerland).

[0044] The present invention will be described in further detail in conjunction with specific embodiments and with reference to data. The following examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention in any way.

Example 1

[0045] A composition of daidzein and taxifolin, where the mass ratio of the daidzein to the taxifolin is 8:25, and specific concentrations of daidzein and taxifolin in the composition are 8 μg/mL and 25 μg/mL respectively.

Example 2

[0046] A composition of daidzein and taxifolin, where the mass ratio of the daidzein to the taxifolin is 8:30, and specific concentrations of daidzein and taxifolin in the composition are 8 μg/mL and 30 μg/mL respectively.

Example 3

[0047] A composition of daidzein and taxifolin, where the mass ratio of the daidzein to the taxifolin is 8:50, and specific concentrations of daidzein and taxifolin in the composition are 8 μg/mL and 50 μg/mL respectively.

Example 4

[0048] A composition of daidzein and taxifolin, where the mass ratio of the daidzein to the taxifolin is 10:25, and specific concentrations of daidzein and taxifolin in the composition are 10 μg/mL and 25 μg/mL respectively.

Example 5

[0049] A composition of daidzein and 3-O-methyl quercetin, where the mass ratio of the daidzein to the 3-O-methyl quercetin is 8:2, and specific concentrations of daidzein and 3 methyl quercetin in the composition are 8 μg/mL and 2 μg/mL respectively.

Example 6

[0050] A composition of daidzein and 3-O-methyl quercetin, where the mass ratio of the daidzein to the 3-O-methyl quercetin is 8:4, and specific concentrations of daidzein and 3-O-methyl quercetin in the composition are 8 μg/mL and 4 μg/mL respectively.

Example 7

[0051] A composition of daidzein and 3-O-methyl quercetin, where the mass ratio of the daidzein to the 3-O-methyl quercetin is 8:6, and specific concentrations of daidzein and 3-O-methyl quercetin in the composition are 8 μg/mL and 6 μg/mL respectively.

Example 8

[0052] A composition of daidzein and 3-O-methyl quercetin, where the mass ratio of the daidzein to the 3-O-methyl quercetin is 10:2, and specific concentrations of daidzein and 3-O-methyl quercetin in the composition are 10 μg/mL and 2 μg/mL respectively.

[0053] Test for Hypoglycemic Effect of Daidzein Composition

[0054] Experimental Method:

[0055] an α-glucosidase solution with a concentration being 0.25 U/mL and a substrate p-nitrophenyl-α-D-glucopyranoside (pNPG) solution with a concentration being 5 mmol/mL were prepared by using a PBS buffer solution (0.1 mol L−1 pH 6.8).

[0056] 40 μL α-glucosidase solution was accurately removed, 100 μL of sample solution to be tested was added respectively, reacted for 10 min at 37° C., then 60 μL of substrate p-nitrophenyl-α-D-glucopyranoside (pNPG) solution was added, reacted for 15 min at 37° C., and an enzyme-linked analyzer measured at a wavelength of 405 nm.

[0057] The solution of the sample to be tested is the daidzein composition of Examples 1-8. First, daidzein, taxifolin, and 3-O-methyl quercetin were respectively prepared into 10 mg/mL mother solutions by using dimethyl sulfoxide (DMSO); and then a sample solution of the specific concentration of the daidzein, taxifolin, and 3-O-methyl quercetin and composition was prepared with PBS buffer solution.

[0058] A positive control group was acarbose (350 μg/mL), a blank group was that samples and enzymes were not added, and a sample blank group was that enzymes were not added.

inhibition rate=[1−(ODsample−ODsample blank)/(ODnegative control−ODblank)]×100%  Calculation formula

[0059] CI values are calculated according to CompuSyn software to evaluate synergistic effect among drugs.

[0060] Combination Index (CI) is used to describe the strength of the synergistic effect of the drugs; CI<1 represents that the synergistic effect exists among drugs, combination can strengthen the therapeutic effect of various monomer drugs, and the smaller the CI values, the stronger the synergistic effect; CI=1 represents that adduction exists among drugs, and a combination result is just linear superposition of the therapeutic effect of various monomer drugs; and CI>1 represents that an antagonistic effect exists among drugs, and combination may reduce the therapeutic effect of each monomer drug inversely.

[0061] 1. Inhibitory Activity of Daidzein Compositions of Example 1 and Example 5 on α-Glucosidase

[0062] The inhibitory activity of daidzein compositions of Example 1 and Example 5 on α-glucosidase is as shown in FIG. 1: inhibition rates of 8 μg/mL daidzein, 25 μg/mL taxifolin, 2 μg/mL 3-O-methyl quercetin and 350 μg/mL acarbose at the corresponding mass concentrations on α-glucosidase are 44.5±2.5%, 40.12±2.1%, 46.23±1.2%, 46.25±3.5% respectively; the inhibition rates of the daidzein and taxifolin composition (8+25 μg/mL) is 67.25±3.35%, and the inhibition rates of the daidzein and 3-O-methyl quercetin (8+2 μg/mL) is 71.56±3.4%. The results show that the composition greatly improves the inhibitory activity on α-glucosidase when used in combination.

[0063] The α-glucosidase inhibitory activity of the daidzein and taxifolin composition at a mass ratio of 8:25 is tested at different concentration gradients, and the concentration gradient of the daidzein and taxifolin composition is (μg/mL): 8+25, 4+12.5, 2+6.25, 1+3.125; the concentration gradient of the daidzein is (μg/mL): 8, 4, 2, 1; and the concentration gradient of the taxifolin is (μg/mL): 25, 12.5, 6.25, 3.125. The results are as shown in FIG. 2: a daidzein and taxifolin composition at a mass ratio of 8:25 increased the inhibitory activity on α-glucosidase at different concentration gradients. The Fa-CI trend graph of a daidzein and taxifolin composition with a mass ratio of 8:25 is as shown in FIG. 3, and it can be seen from FIG. 3 that the CI values of daidzein and taxifolin are both below 1.0, showing a synergistic effect.

[0064] The α-glucosidase inhibitory activity of the daidzein and 3-O-methyl quercetin composition at a mass ratio of 8:2 is tested at different concentration gradients, and the concentration gradient of the daidzein and 3-O-methyl quercetin composition was (μg/mL): 8+2, 4+1, 2+0.5, 1+0.25; the concentration gradient of the daidzein was (μg/mL): 8, 4, 2, 1; and the concentration gradient of the 3-O-methyl quercetin was (μg/mL): 2, 1, 0.5, 0.25. The results are shown in FIG. 4: a daidzein and 3-O-methyl quercetin composition at a mass ratio of 8:2 also correspondingly increased the inhibitory activity on α-glucosidase at different concentration gradients. The Fa-CI trend graph of a daidzein and 3-O-methyl quercetin composition at a mass ratio of 8:2 is as shown in FIG. 5, and it can be seen from FIG. 5 that the CI values of daidzein and 3-O-methyl quercetin are both below 1.0, showing a synergistic effect. The combination index (CI) of the daidzein composition of Example 1 and Example 5 is shown in Table 1:

TABLE-US-00001 TABLE 1 Combination index (CI) of the daidzein composition of Example 1 and Example 5 Mass CI Compound ratio GI.sub.50 GI.sub.75 GI.sub.90 CI.sub.avg Daidzein + 8:25 0.74 ± 0.01 0.79 ± 0.02 0.86 ± 0.01 0.82 taxifolin Daidzein + 8:2  0.71 ± 0.02 0.62 ± 0.03 0.55 ± 0.02 0.60 3-O-methyl quercetin

[0065] Data comes from results of three independent experiments and is represented as average value±standard difference

[0066] From the results in Table 1, it can be seen that when a combination of the daidzein and taxifolin (8:25) and a combination of the daidzein and 3-O-methyl quercetin (8:2) are used, the combination indexes (CI) both are less than 1, showing a synergistic effect, where an average of combination index (CI.sub.avg) of the daidzein and taxifolin (8:25) is 0.82, showing a synergistic effect; and an average of combination index (CI.sub.avg) of the daidzein and 3-O-methyl quercetin (8:2) is 0.60, showing a relatively strong synergistic effect.

[0067] 2. Inhibitory Activity of Daidzein Compositions of Example 2 and Example 6 on α-Glucosidase

[0068] The inhibitory activity of daidzein compositions of Example 2 and Example 6 on α-glucosidase is shown in FIG. 6: inhibition rates of 8 μg/mL daidzein, 30 μg/mL taxifolin, 4 μg/mL 3-O-methyl quercetin and 350 μg/mL acarbose at the corresponding mass concentrations on α-glucosidase are 44.5±2.5%, 54.5±2.4%, 53.52±3.2%, 46.25±3.5% respectively; the inhibition rates of the daidzein and taxifolin composition (8+30 μg/mL) is 58.6±3.5%, and the inhibition rates of the daidzein and 3-O-methyl quercetin (8+4 μg/mL) is 64.5±2.4%. The results show that the composition improves the inhibitory activity of α-glucosidase when used in combination.

[0069] The α-glucosidase inhibitory activity of the daidzein and taxifolin composition at a mass ratio of 8:30 is tested at different concentration gradients, and the concentration gradient of the daidzein and taxifolin composition is (μg/mL): 8+30, 4+15, 2+7.5, 1+3.75; the concentration gradient of the daidzein is (μg/mL): 8, 4, 2, 1; the concentration gradient of the taxifolin is (μg/mL): 30, 15, 7.5, 3.75; and the results are shown in FIG. 7.

[0070] The α-glucosidase inhibitory activity of the daidzein and 3-O-methyl quercetin composition at a mass ratio of 8:4 is tested at different concentration gradients, and the concentration gradient of the daidzein and 3-O-methyl quercetin composition is (μg/mL): 8+4, 4+2, 2+1, 1+0.5; the concentration gradient of the daidzein is (μg/mL): 8, 4, 2, 1; the concentration gradient of the 3-O-methyl quercetin is (μg/mL): 4, 2, 1, 0.5; and the results are shown in FIG. 8. The combination index (CI) of the daidzein composition of Example 2 and Example 6 is shown in Table 2:

TABLE-US-00002 TABLE 2 Combination index (CI) of the daidzein composition of Example 2 and Example 6 Mass CI Compound ratio GI.sub.50 GI.sub.75 GI.sub.90 CI.sub.avg Daidzein + 8:30 >1 >1 >1 >1 taxifolin Daidzein + 8:4  1.09 ± 0.02 0.96 ± 0.02 0.84 ± 0.02 0.92 3-O-methyl quercetin

[0071] Data comes from results of three independent experiments and is represented as average value±standard difference

[0072] From the results in Table 2, it can be seen that although a combination of the daidzein and taxifolin (8:30) composition and a combination of the daidzein and 3-O-methyl quercetin (8:4) have improved inhibitory activity on α-glucosidase; however, when the combination of the daidzein and taxifolin (8:30) composition is used, the combination index (CI) is greater than 1, showing an antagonistic effect; and when the combination of the daidzein and 3-O-methyl quercetin (8:4) is used, the combination index (CI) is close to 1, showing a weak synergistic effect.

[0073] 3. Inhibitory Activity of Daidzein Compositions of Example 3 and Example 7 on α-Glucosidase

[0074] The inhibitory activity of daidzein compositions of Example 3 and Example 7 on α-glucosidase is shown in FIG. 9: inhibition rates of 8 μg/mL daidzein, 50 μg/mL taxifolin, 6 μg/mL 3-O-methyl quercetin and 350 μg/mL acarbose at the corresponding mass concentrations on α-glucosidase are 44.5±2.5%, 75.21±3.4%, 61.72±3.5%, 46.25±3.5% respectively; the inhibition rates of the daidzein and taxifolin composition (8+50 μg/mL) is 67.8±3.7%, and the inhibition rates of the daidzein and 3-O-methyl quercetin (8+6 μg/mL) is 58.9±3.4%. The results show that the composition does not significantly improve the inhibitory activity on α-glucosidase when used in combination.

[0075] The α-glucosidase inhibitory activity of the daidzein and taxifolin composition at a mass ratio of 8:50 is tested at different concentration gradients, and the concentration gradient of the daidzein and taxifolin composition is (μg/mL): 8+50, 4+25, 2+12.5, 1+6.25; the concentration gradient of the daidzein is (μg/mL): 8, 4, 2, 1; the concentration gradient of the taxifolin is (μg/mL): 50, 25, 12.5, 6.25; and the results are shown in FIG. 10.

[0076] The α-glucosidase inhibitory activity of the daidzein and 3-O-methyl quercetin composition at a mass ratio of 8:6 is tested at different concentration gradients, and the concentration gradient of the daidzein and 3-O-methyl quercetin composition is (μg/mL): 8+6, 4+3, 2+1.5, 1+0.75; the concentration gradient of the daidzein is (μg/mL): 8, 4, 2, 1; the concentration gradient of the 3-O-methyl quercetin is (μg/mL): 6, 3, 1.5, 0.75; and the results are shown in FIG. 11.

[0077] The combination index (CI) of the daidzein composition of Example 3 and Example 7 is shown in Table 3:

TABLE-US-00003 TABLE 3 Combination index (CI) of the daidzein composition of Example 3 and Example 7 Mass CI Compound ratio GI.sub.50 GI.sub.75 GI.sub.90 CI.sub.avg Daidzein + 8:50 >1 >1 >1 >1 taxifolin Daidzein + 8:6  >1 >1 >1 >1 3-O-methyl quercetin

[0078] Data comes from results of three independent experiments and is represented as average value±standard difference

[0079] From the results in Table 3, it can be seen that when a combination of the daidzein and taxifolin (8:50) and a combination of the daidzein and 3-O-methyl quercetin (8:6) composition are used, the combination indexes (CI) both are greater than 1, showing an antagonistic effect.

[0080] 4. Inhibitory Activity of Daidzein Compositions of Example 4 and Example 8 on α-Glucosidase

[0081] The inhibitory activity of daidzein compositions of Example 4 and Example 8 on α-glucosidase is shown in FIG. 12: inhibition rates of 10 μg/mL daidzein, 25 μg/mL taxifolin, 2 μg/mL 3-O-methyl quercetin and 350 μg/mL acarbose at the corresponding mass concentrations on α-glucosidase are 52.25±2.5%, 40.12±2.1%, 46.23±1.2%, 46.25±3.5% respectively; the inhibition rates of the daidzein and taxifolin composition (10+25 μg/mL) is 62.3±1.7%, and the inhibition rates of the daidzein and 3-O-methyl quercetin (10+2 μg/mL) is 45.2±2.5%. The results show that the composition does not significantly improve the inhibitory activity on α-glucosidase when used in combination.

[0082] The α-glucosidase inhibitory activity of the daidzein and taxifolin composition at a mass ratio of 10:25 is tested at different concentration gradients, and the concentration gradient of the daidzein and taxifolin composition is (μg/mL): 10+25, 5+12.5, 2.5+6.25, 1.25+3.125; the concentration gradient of the daidzein is (μg/mL): 10, 5, 2.5, 1.25; the concentration gradient of the taxifolin is (μg/mL): 25, 12.5, 6.25, 3.125; and the results are shown in FIG. 13.

[0083] The α-glucosidase inhibitory activity of the daidzein and 3-O-methyl quercetin composition at a mass ratio of 10:2 is tested at different concentration gradients, and the concentration gradient of the daidzein and 3-O-methyl quercetin composition is (μg/mL): 10+2, 5+1, 2.5+0.5, 1.25+0.25; the concentration gradient of the daidzein is (μg/mL): 10, 5, 2.5, 1.25; the concentration gradient of the 3-O-methyl quercetin is (μg/mL): 2, 1, 0.5, 0.25; and the results are shown in FIG. 14.

[0084] The combination index (CI) of the daidzein composition of Example 4 and Example 8 is shown in Table 4:

TABLE-US-00004 TABLE 4 Combination index (CI) of the daidzein composition of Example 4 and Example 8 Mass CI Compound ratio GI.sub.50 GI.sub.75 GI.sub.90 CI.sub.avg Daidzein + 10:25 1.1 ± 0.02 1.0 ± 0.01 0.90 ± 0.03 0.97 taxifolin Daidzein + 10:2  >1 >1 >1 >1 3-O-methyl quercetin

[0085] Data comes from results of three independent experiments and is represented as average value±standard difference

[0086] From the results in Table 4, it can be seen that a combination of the daidzein and taxifolin (10:25) improves inhibitory activity on α-glucosidase, while a combination of the daidzein and 3-O-methyl quercetin (10:2) composition has no significant effect; when the combination of the daidzein and taxifolin (10:25) is used, the combination index (CI) is close to 1, showing a weak synergistic effect, and when the combination of the daidzein and 3-O-methyl quercetin (10:2) composition is used, the combination index (CI) is greater than 1, showing an antagonistic effect.

Comparative Example 1

[0087] This example demonstrates that the combination of each monomeric compound and daidzein does not have a synergistic effect. Each monomeric compound is selected from kaempferide, kaempferol, diosmetin, herbacetin, myricetin, morin, genkwanin, baicalein, hesperetin, fisetin, chrysin, epigallocatechin gallate, delphinidin, cyanidin, isoliquiritigenin, formononetin, and biochanin A.

[0088] First, the inhibition rates of various monomeric compounds under corresponding concentrations on the α-glucosidase are tested according to the above method, as shown in the following Table 5:

TABLE-US-00005 TABLE 5 Monomer Mass concentration Inhibition compound (μg/mL) rate Daidzein 8 44.5 ± 2.5% Kaempferide 5 30.8 ± 1.3% Kaempferol 2.5 40.83 ± 2.3%  Diosmetin 100 43.0 ± 2.1% Herbacetin 2.5 35.2 ± 1.2% Myricetin 1 41.2 ± 1.5% Morin 1 41.2 ± 2.7% Genkwanin 35 70.12 ± 5.5%  Baicalein 10 38.8 ± 3.3% Hesperetin 30 45.2 ± 3.2% Fisetin 6 46.5 ± 2.3% Chrysin 100 51.2 ± 5.5% Epigallocatechin gallate 0.06 42.5 ± 3.5% Delphinidin 1 50.2 ± 4.3% Cyanidin 0.7 47.5 ± 1.4% Isoliquiritigenin 4 35.2 ± 2.5% Formononetin 20 60.07 ± 5.3%  Biochanin A 0.7 38.5 ± 2.1%

[0089] Then, each monomeric compound is combined with the daidzein, and the α-glucosidase inhibition rate of the composition is measured, as shown in the following Table 6:

TABLE-US-00006 TABLE 6 Mass concentration Monomer compound Monomer compound ratio Inhibition rate [00004] [00005] 8:5 34.5 ± 1.3% [00006]   8:2.5 45.1 ± 2.8% [00007]  8:12 46.3 ± 3.7% [00008]   8:2.5 31.8 ± 1.8% [00009] 8:1 17.4 ± 2.3% [00010] 8:1 38.5 ± 2.1% [00011]  8:35 28.5 ± 1.5% [00012]  8:10 38.3 ± 2.5% [00013]  8:30 38.1 ± 2.3% [00014]  8:100 24.7 ± 1.2% [00015] 8:6 28.3 ± 1.5% [00016]   8:0.06 34.5 ± 2.3% [00017] 8:1 35.5 ± 2.6% [00018]   8:0.7 25.7 ± 2.3% [00019] 8:4 37.3 ± 1.5% [00020]  8:20 51.2 ± 2.4% [00021]   8:0.7 42.6 ± 3.1%

[0090] It can be seen from the Table 6 that after each monomeric compound is combined with the daidzein, the inhibition rate of composition thereof is directly lower than effect inhibition rate of a single compound, and the composition actually shows an antagonistic effect without a synergistic effect.

Comparative Example 2

[0091] This example demonstrates that the combination of each monomeric compound and 3-O-methyl quercetin does not have a synergistic effect. Each monomeric compound is selected from kaempferol, luteolin, vincetoxicoside B, herbacetin, myricetin, dihydromorin, vitexin, baicalein, taxifolin, hesperetin, chrysin, epigallocatechin gallate, delphinidin, cyanidin, isoliquiritigenin, phloretin, and biochanin A.

[0092] First, the inhibition rates of various monomeric compounds under corresponding concentrations on the α-glucosidase are tested according to the above method, as shown in the following Table 7:

TABLE-US-00007 TABLE 7 Monomer Mass concentration Inhibition compound (μg/mL) rate 3-Omethyl quercetin 2 46.23 ± 1.2%  Kaempferol 2.5 40.83 ± 2.3%  Luteolin 1 45.5 ± 2.7% Vincetoxicoside 12 48.7 ± 2.1% Herbacetin 2.5 35.2 ± 1.2% Myricetin 1 41.2 ± 1.5% Dihydromorin 15 25.7 ± 4.7% Vitexin 10 29.2 ± 1.4% Baicalein 10 38.8 ± 3.3% Taxifolin 25 40.12 ± 2.1%  Hesperetin 30 45.2 ± 3.2% Chrysin 100 51.2 ± 5.5% Epigallocatechin gallate 0.06 42.5 ± 3.5% Delphinidin 1 50.2 ± 4.3% Cyanidin 0.7 47.5 ± 1.4% Isoliquiritigenin 4 35.2 ± 2.5% Phloretin 8 46.3 ± 2.7% Biochanin A 0.7 38.5 ± 2.1%

[0093] Then, each monomeric compound is combined with the 3-O-methyl quercetin, and the α-glucosidase inhibition rate of the composition is measured, as shown in the following Table 8:

TABLE-US-00008 TABLE 8 Mass concentration Monomer compound Monomer compound ratio Inhibition rate 3-O-methyl quercetin [00022]   2:2.5 44.25 ± 2.5%  [00023] 2:1 25.5 ± 3.2% [00024]  2:12 42.3 ± 3.7% [00025]   2:2.5 42.5 ± 1.8% [00026] 2:1 40.3 ± 2.3% [00027]  2:15 43.5 ± 1.8% [00028]  2:10 44.4 ± 1.5% [00029]  2:10 46.2 ± 2.3% [00030]  2:25 44.3 ± 4.9% [00031]  2:30 42.7 ± 3.3% [00032]  2:100 45.4 ± 3.9% [00033]   2:0.06 42.5 ± 2.8% [00034] 2:1 34.5 ± 3.1% [00035]   2:0.7 37.6 ± 3.6% [00036] 2:4 46.1 ± 1.5% [00037] 2:8 43.2 ± 2.1% [00038]   2:0.7 45.2 ± 2.4%

[0094] It can be seen from the Table 8 that after each monomeric compound is combined with the 3-O-methyl quercetin, the inhibition rate of composition thereof is directly lower than effect inhibition rate of a single compound, and the composition actually shows an antagonistic effect without a synergistic effect.

[0095] The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person familiar with the profession may use the technical content disclosed above to change or modify them into the equivalent embodiments of equivalent changes. However, any simple modification, equivalent change and modification made in accordance with the technical essence of the invention without departing from the technical solution of the invention are still within the scope of protection of the technical solutions of the invention.