A benzogchromone compound with antibacterial activity, its preparation method and application

Abstract

The present invention belongs to the technical field of food chemistry, and particularly relates to a benzo[g]chromone compound with antibacterial activity, a preparation method thereof, and an application thereof. The structural formula of the antibacterial benzo[g]chromone compound is as follows: #imgabs0#. The antibacterial benzo[g]chromone compound of the present invention is obtained from the medicinal plant Cassia obtusifolia ( Chamaecrista rotundifolia It is isolated from the wild-type chlorinated ...

Description

Technical Field

[0001] The present invention belongs to the technical field of plant chemistry, and in particular relates to a benzo[g]chromone compound with antibacterial activity, a preparation method and an application thereof. Background Art

[0002] Cassia tora (scientific name: Chamaecrista rotundifolia Pers. Greene is a semi-erect perennial herbaceous plant in the Fabaceae family, Cassia genus. Round-leaved Cassia is tolerant to acidity, drought, and infertility, offers high yields, strong nitrogen-fixing abilities, high nutrient content, and is pest and disease-free.

[0003] Years of cultivation have shown that Cassia obtusifolia, as a perennial herb, is suitable for cultivation on mountainous and sloping lands. It helps prevent soil erosion and water loss, and also plays a significant role in maintaining ecological balance. Cassia obtusifolia has a crude protein content of approximately 20%, and is also high in crude fat, nitrogen, phosphorus, and calcium, while its crude fiber content is relatively low. Its yield per mu reaches 1,500 kg, equivalent to the crude protein content of 3,000 kg of corn, making it an excellent forage crop with high economic value. Cassia obtusifolia also has a wide range of medicinal uses, including heat-clearing and detoxifying, diuretic and stranguria-relieving, lipid-lowering, antibacterial, and radiation-resistant properties. Currently, relatively little research has been conducted on its secondary metabolites. Summary of the Invention

[0004] The first purpose of the present invention is to provide a benzo[g]chromone compound with antibacterial activity; the second purpose is to provide a method for preparing the benzo[g]chromone compound with antibacterial activity; and the third purpose is to provide an application of the benzo[g]chromone compound with antibacterial activity.

[0005] The first object of the present invention is achieved by: the benzo[g]chromone compound having antibacterial activity is prepared from the medicinal plant Cassia obtusifolia ( Chamaecrista rotundifolia The whole plant was used as raw material, and the product was prepared through pretreatment, extract extraction, MCI decolorization, silica gel column chromatography and high performance liquid chromatography separation. It is named: 6-methoxy-2,9-dimethylbenzo [2,3-g]-4H-chromone, and its English name is: 6-methoxy-2,9-dimethylbenzo [2,3-g]-4H-chromone, with the following structure:

[0006] .

[0007] The second object of the present invention is achieved by using the medicinal plant Cassia obtusifolia ( Chamaecrista rotundifolia ) whole plant is used as raw material, and the preparation is carried out through pretreatment, extract extraction, MCI decolorization, silica gel column chromatography and high performance liquid chromatography separation, which specifically includes the following steps:

[0008] A. Pretreatment: Grind or cut the whole plant of the raw medicinal plant Cassia tora into segments to obtain material a;

[0009] B. Extraction: Add 2 to 6 times the mass of organic extraction solvent to material a, soak and extract 2 to 5 times at room temperature, each extraction time is 12 to 20 hours, combine the extracts and filter to obtain sample extract b;

[0010] C. MCI decolorization: The sample extract was decolorized on an MCI column, the effluent was collected and concentrated under reduced pressure to obtain extract C;

[0011] D. Silica gel column chromatography:

[0012] 1) Add 200-250 mesh silica gel in an amount 3-10 times the weight of extract C to the column, and perform gradient elution with a chloroform-methanol solution in a volume ratio of 20:1 to 1:1. Monitor by TLC and combine the same fractions.

[0013] 2) The 9:1 chloroform-methanol eluate was concentrated under reduced pressure to obtain fraction d. A 200-250 mesh silica gel column was loaded with 3-10 times the weight of the obtained fraction d. Gradient elution was performed with a 1:0-1:2 volume ratio of chloroform-acetone solution. The eluate was monitored by TLC and the same fractions were combined.

[0014] E. High performance liquid chromatography separation: The eluate obtained by eluting with a chloroform-acetone solution in a ratio of 8:2 is separated and purified by high performance liquid chromatography to obtain the target benzo[g]chromone compounds with antibacterial activity.

[0015] The structures of the prepared benzo[g]chromone compounds with antibacterial activity were identified by the following method:

[0016] The compound was a yellow colloid. HRESI-MS showed that its quasi-molecular ion peak was 277.0831[M+Na] + (calculated value 277.0835), combined 1 H NMR, 13 C and DEPT spectra confirmed that its molecular formula is C 16 H 14 NaO3, degree of unsaturation is 10.

[0017] The infrared spectrum shows carbonyl (1665) and aromatic rings (1616, 1570 and 1448 cm -1 The UV spectrum has maximum absorption at 215, 272, and 364 nm, which also indicates that there may be aromatic ring structures in the compound.

[0018] Compound 1H and 13 C NMR spectrum (see Table 1, Figure 1 and Figure 2 ) showed that it contains 16 carbons and 14 hydrogens, including 1 tetrasubstituted naphthalene ring (C-5~C-13, H-5, H-7, H-8 and H-10), and 1 α,β -unsaturated carbonyl (-OC=CH-CO-, C-2~C-4, H-3), two methyl groups (C-15, C-16, H3-15 and H3-16), and one methoxy group ( δ C 56.2 and δ H 3.80s). Further analysis of its NMR data, α,β The unsaturated carbonyl group should be connected to the naphthalene ring to form a pyran ring, forming a b-benzo[g]chromone skeleton, supporting the presence of ten unsaturated residues and two oxidized aromatic carbons (C-11 and C-2). This speculation was further confirmed by HMBC correlations between H-3 and C-2 / C-4 / C-12, H-5 to C-4 / C-6, H-7 to C-13, H-8 and C-14, and H-10 and C-9.

[0019] Table 1. Compounds of the present invention 1 H NMR and 13 C NMR data (CDCl3)

[0020]

[0021] After the parent compound is determined, the remaining substituents (methoxy and two methyl groups) can be regarded as substituents on benzo[g]chromone. The methoxy group is substituted at the C-6 position and can be replaced by the methoxy hydrogen ( δ H The HMBC correlations of H3-15 with C-2 / C-3, H3-16 with C-8 / C-9 / C-14, H-3 with C-15, and H-8 with C-16 confirmed the presence of two methyl groups at the C-2 and C-9 positions. Thus, the structure of the compound of the present invention was determined and named 6-methoxy-2,9-dimethylbenzo[2,3-g]-4H-chromone.

[0022] Infrared, UV and mass spectrometry data of the compound:

[0023] UV spectrum (methanol), λ max (log ε) 215 (4.42), 272 (4.18), 364 (3.96) nm; Infrared spectrum (potassium bromide tablet): ν max 2942, 1665, 1616, 1570, 1448, 1279, 1163, 1038, 960 cm -1 ; 1 H and 13 CNMR data (500 and 125 MHz, (C5D5N), see Table 1; positive ion mode ESIMS m / z 277 [M+Na] + ; Positive ion mode HRESIMS m / z 277.0831 [M+Na] + (Calculated value 277.0835, C 16 H 14 NaO3).

[0024] The third object of the present invention is achieved by using the antibacterial active benzo[g]chromone compounds in the preparation of cosmetic additives.

[0025] The present invention studies the chemical components of Cassia obtusifolia and isolates a benzo[g]chromone compound with antibacterial activity. The compound is derived from a natural product and has strong absorption of ultraviolet rays in both UVA and UVB regions, can effectively prevent skin from being sunburned and tanned, has a significant sun protection effect, and is an ideal sunscreen cosmetic additive.

[0026] The advantages of the present invention are:

[0027] (1) The compound of the present invention is a benzo[g]chromone obtained from the medicinal plant Cassia obtusifolia ( Chamaecrista rotundifolia To control soil erosion, Cassia tora is cultivated on a large scale in barren wastelands and sloping lands. It has a high biomass yield, a wide range of raw material sources, low cost, and is easily isolated and prepared.

[0028] (2) The compound of the present invention has a good tyrosinase inhibition effect and also has significant antibacterial activity. It can be used in cosmetic additives without adding additional preservatives. Moreover, the compound has a significant inhibitory effect on both representative Gram-positive and Gram-negative strains and has a good broad-spectrum antibacterial property. When added to cosmetics, it can exert its efficacy while inhibiting bacterial growth.

[0029] (3) The compound of the present invention is derived from natural products, is safe and non-toxic, has strong absorption of ultraviolet rays in both UVA and UVB regions, can effectively prevent skin from being red and tanned, has a significant sun protection effect, and is an ideal sunscreen cosmetic additive. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The nuclear magnetic resonance carbon spectrum of the antibacterial active benzo[g]chromone compounds of the present invention ( 13 C NMR);

[0031] Figure 2 The nuclear magnetic resonance hydrogen spectrum of the antibacterial active benzo[g]chromone compound of the present invention is ( 1 H NMR);

[0032] Figure 3 Key HMBC correlation diagram of the antimicrobial active benzo[g]chromone compounds of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described below with reference to the embodiments and drawings, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention fall within the scope of protection of the present invention.

[0034] The benzo[g]chromone compounds with antibacterial activity described in the present invention are derived from the medicinal plant Cassia tora ( Chamaecrista rotundifolia The whole plant was used as raw material, and the product was prepared through pretreatment, extract extraction, MCI decolorization, silica gel column chromatography and high performance liquid chromatography separation. It is named: 6-methoxy-2,9-dimethylbenzo [2,3-g]-4H-chromone, and its English name is: 6-methoxy-2,9-dimethylbenzo [2,3-g]-4H-chromone, with the following structure:

[0035] .

[0036] The preparation method of the benzo[g]chromone compounds with antibacterial activity of the present invention is to use the medicinal plant Cassia obtusifolia ( Chamaecrista rotundifolia ) whole plant is used as raw material, and the preparation is carried out through pretreatment, extract extraction, MCI decolorization, silica gel column chromatography and high performance liquid chromatography separation, which specifically includes the following steps:

[0037] A. Pretreatment: Grind or cut the whole plant of the raw medicinal plant Cassia tora into segments to obtain material a;

[0038] B. Extraction: Add 2 to 6 times the mass of organic extraction solvent to material a, soak and extract 2 to 5 times at room temperature, each extraction time is 12 to 20 hours, combine the extracts and filter to obtain sample extract b;

[0039] C. MCI decolorization: The sample extract was decolorized on an MCI column, the effluent was collected and concentrated under reduced pressure to obtain extract C;

[0040] D. Silica gel column chromatography:

[0041] 1) Add 200-250 mesh silica gel in an amount 3-10 times the weight of extract C to the column, and perform gradient elution with a chloroform-methanol solution in a volume ratio of 20:1 to 1:1. Monitor by TLC and combine the same fractions.

[0042] 2) The 9:1 chloroform-methanol eluate was concentrated under reduced pressure to obtain fraction d. A 200-250 mesh silica gel column was loaded with 3-10 times the weight of the obtained fraction d. Gradient elution was performed with a 1:0-1:2 volume ratio of chloroform-acetone solution. The eluate was monitored by TLC and the same fractions were combined.

[0043] E. High performance liquid chromatography separation: The eluate obtained by eluting with a chloroform-acetone solution in a ratio of 8:2 is separated and purified by high performance liquid chromatography to obtain the target benzo[g]chromone compounds with antibacterial activity.

[0044] The organic extraction solvent in step B is a methanol aqueous solution with a mass concentration of 70% to 100%, an ethanol aqueous solution with a mass concentration of 70% to 100%, or an acetone aqueous solution with a mass concentration of 70% to 100%.

[0045] Step D also includes a sample mixing step before loading onto the column, wherein the material C is dissolved in an organic solvent at a volume of 1.5 to 3 times the weight of the material C and then 0.8 to 2.0 times the weight of the material C is added with 80 to 100 mesh silica gel.

[0046] The organic solvent is pure methanol or pure acetone.

[0047] D. The volume ratios of the chloroform-methanol solution described in step 1) are 20:1, 9:1, 8:2, 7:3, 6:4 and 1:1.

[0048] In step E, the high performance liquid chromatography separation and purification uses a methanol-water solution with a volume concentration of 55-62% as the mobile phase, a flow rate of 12 mL / min, a 2.12×250 mm, 5 μm Zorbax PrepHT GF reverse phase preparative column as the stationary phase, an ultraviolet detector with a detection wavelength of 364 nm, 0.5~1.0 mL is injected each time, and the chromatographic peak of 28~35 min is collected. After multiple accumulation, the target antibacterial active benzo[g]chromone compound is evaporated to dryness.

[0049] The application of the present invention is the application of the antibacterial active benzo[g]chromone compounds in the preparation of cosmetic additives.

[0050] The present invention will be further described below with reference to specific examples of Cassia obtusifolia raw materials from different production areas in Yunnan:

[0051] Example 1

[0052] This embodiment provides a method for preparing the antibacterial active benzo[g]chromone compounds of the present invention. The method comprises the steps of extract extraction, silica gel column chromatography, and high performance liquid chromatography separation. The medicinal plant Cassia tora is used as the raw material. The specific operations are as follows:

[0053] The medicinal plant Cassia obtusifolia is produced in Yuanjiang, Yuxi, Yunnan. The raw material is a sample of the whole plant of the medicinal plant Cassia obtusifolia, which is crushed or cut into sections. The sample is extracted with a 70% methanol aqueous solution for 4 times, each time for 15 hours. The combined extracts are decolorized on an MCI column, and the eluent is concentrated under reduced pressure to obtain an extract. The extract is dissolved in methanol 2 times the mass of the extract, and then 90 mesh silica gel is added to mix the sample. The column is packed with 220 mesh silica gel, and the sample is loaded onto the column after mixing. Gradient elution is performed using chloroform-methanol eluents with volume ratios of 20:1, 9:1, 8:2, 7:3, 6:4, and 1:1, respectively. The gradient eluents are collected, concentrated, and monitored by TLC. The same fractions are combined to obtain 6 fractions AF, among which the collected sample B (9:1) A 208g portion was added to a 220-mesh silica gel column, 8 times the amount of the extract, and gradient elution was performed using chloroform-acetone ratios of 1:0, 4:1, 1:1, and 1:2, respectively. The gradient eluates were collected, concentrated, and monitored by TLC. Identical fractions were combined to yield three fractions, of which 204g was the 4:1 fraction. This fraction was then eluted using a 2.12×250mm, 5µm Zorbax PrepHT GF reverse-phase preparative column with 58% methanol as the mobile phase at a flow rate of 12ml / min. The column was then chromatographically analyzed using a UV detector at a wavelength of 364nm. 0.8mL of sample was injected each time, and the chromatographic peak at 30.4min was collected. Multiple additions were performed and evaporated to dryness to yield the antibacterial benzo[g]chromone compound described herein. The compound structure was identified by the following method.

[0054] The compound was a yellow colloid. HRESI-MS showed that its quasi-molecular ion peak was 277.0831[M+Na] + (calculated value 277.0835), combined 1 H NMR, 13 C and DEPT spectra confirmed that its molecular formula is C 16 H 14 NaO3, degree of unsaturation is 10.

[0055] The infrared spectrum shows carbonyl (1665) and aromatic rings (1616, 1570 and 1448 cm -1The UV spectrum has maximum absorption at 215, 272, and 364 nm, which also indicates that there may be aromatic ring structures in the compound.

[0056] Compound 1 H and 13 C NMR spectrum (see Table 1, Figure 1 and Figure 2 ) showed that it contains 16 carbons and 14 hydrogens, including 1 tetrasubstituted naphthalene ring (C-5~C-13, H-5, H-7, H-8 and H-10), and 1 α,β -unsaturated carbonyl (-OC=CH-CO-, C-2~C-4, H-3), two methyl groups (C-15, C-16, H3-15 and H3-16), and one methoxy group ( δ C 56.2 and δ H 3.80s). Further analysis of its NMR data, α,β The unsaturated carbonyl group should be connected to the naphthalene ring to form a pyran ring, forming a b-benzo[g]chromone skeleton, supporting the presence of ten degrees of unsaturation in the compound and two oxidized aromatic carbons (C-11 and C-2). This speculation was further confirmed by HMBC correlations between H-3 and C-2 / C-4 / C-12, H-5 and C-4 / C-6, H-7 and C-13, H-8 and C-14, and H-10 and C-9.

[0057] After the parent compound is determined, the remaining substituents (methoxy and two methyl groups) can be regarded as substituents on benzo[g]chromone. The methoxy group is substituted at the C-6 position and can be replaced by the methoxy hydrogen ( δ H The HMBC correlation between H3-15 and C-2 / C-3, H3-16 and C-8 / C-9 / C-14, H-3 and C-15, and H-8 and C-16 confirmed the presence of two methyl groups at the C-2 and C-9 positions. Thus, the structure of the compound of the present invention was determined and named 6-methoxy-2,9-dimethylbenzo[2,3-g]-4H-chromone.

[0058] Example 2

[0059] This embodiment provides a method for preparing the antibacterial active benzo[g]chromone compounds of the present invention. The method comprises the steps of extract extraction, silica gel column chromatography, and high performance liquid chromatography separation. The medicinal plant Cassia tora is used as the raw material. The specific operations are as follows:

[0060] The medicinal plant Cassia toratum used is produced in the estuary of the Honghe River in Yunnan. The raw material is a sample of the whole plant of the medicinal plant Cassia toratum, which is crushed or cut into sections. It is soaked and extracted with an ethanol aqueous solution with a mass concentration of 80% for 5 times, each time for 12 hours. The combined extracts were decolorized on an MCI column, and the eluate was concentrated under reduced pressure to obtain an extract. The extract was dissolved in acetone 3 times the mass of the extract, and then 100-mesh silica gel was added to mix the sample, and the column was loaded with 250-mesh silica gel. After mixing, the sample was loaded onto the column. Gradient elution was performed with chloroform-methanol eluents in volume ratios of 20:1, 9:1, 8:2, 7:3, 6:4, and 1:1, respectively. The gradient eluents were collected and concentrated. After TLC monitoring, the same fractions were combined to obtain 6 fractions AF. Among them, 244 g of the collected sample B (9:1) fraction was added with 250-mesh silica gel 10 times the mass of the extract and loaded onto the column. Gradient elution was performed with chloroform-acetone eluents in volume ratios of 1:0 to 1:2, respectively. The gradient eluents were collected and concentrated. After TLC monitoring, the same fractions were combined to obtain 3 fractions, of which 201 g of the 8:2 fraction was washed with 60% methanol as the mobile phase at a flow rate of 12 ml / min. The column was 2.12×250 mm, 5 µm The stationary phase was a Zorbax PrepHT GF reverse phase preparative column, the detection wavelength of the UV detector was 364 nm, 0.5-1.0 mL was injected each time, and the chromatographic peak of 33.6 min was collected. After multiple accumulations, the chromatographic peak was evaporated to dryness to obtain the antibacterial active benzo[g]chromone compound of the present invention. After identification, the identification method was the same as in Example 1, and the molecular formula was C 16 H 14 O3.

[0061] Example 3

[0062] This embodiment provides a method for preparing the antibacterial active benzo[g]chromone compounds of the present invention. The method comprises the steps of extract extraction, silica gel column chromatography, and high performance liquid chromatography separation. The medicinal plant Cassia tora is used as the raw material. The specific operations are as follows:

[0063] The medicinal plant Cassia obtusifolia used is produced in Menghai, Xishuangbanna, Yunnan. The raw material is a sample of the whole plant of the medicinal plant Cassia obtusifolia, which is crushed or cut into sections. The sample is extracted twice with an acetone aqueous solution of 80% by mass, each time for 12 hours. The combined extracts are decolorized on an MCI column, and the eluate is concentrated under reduced pressure to obtain an extract. The extract is dissolved in methanol with a volume of 1.5 times that of the extract, and then 80-mesh silica gel is added to mix the sample. The column is packed with 200-mesh silica gel, and the sample is loaded onto the column after mixing. Gradient elution is performed using chloroform-methanol eluents with volume ratios of 20:1, 9:1, 8:2, 7:3, 6:4, and 1:1, respectively. The gradient eluents are collected, concentrated, and monitored by TLC. The same fractions are combined to obtain 6 fractions AF, among which the collected sample B (9:1) 206g of the extract was added to a 200-mesh silica gel column with 3 times the amount of the extract, and gradient elution was performed with chloroform-acetone eluents in volume ratios of 1:0, 8:2, 1:1, and 1:2. The gradient eluents were collected and concentrated, and monitored by TLC. The same fractions were combined to obtain three fractions, of which 183g of the 8:2 fraction was then used as the mobile phase with 62% methanol at a flow rate of 12ml / min. A 2.12×250mm, 5µm Zorbax PrepHT GF reverse phase preparative column was used as the stationary phase. The UV detector was detected at a wavelength of 364nm. 0.5-1.0mL was injected each time, and the chromatographic peak at 34.9min was collected. After multiple accumulations, the chromatographic peak was evaporated to dryness to obtain the antibacterial active benzo[g]chromone compound of the present invention. After identification, the identification method was the same as in Example 1, and the molecular formula was C 16 H 14 O3.

[0064] Example 4

[0065] The antibacterial active benzo[g]chromone compounds prepared in Example 1 were tested:

[0066] A. Antibacterial activity test of the compounds: The antibacterial activity of the compounds was determined according to the microdilution method recommended by the Clinical and Laboratory Standards Institute (CLSI). Representative Gram-positive strains (Staphylococcus aureus (Staphylococcus genus), beta-hemolytic Streptococcus (Streptococcus genus), Streptococcus pneumoniae (Streptococcus genus)) and representative Gram-negative strains (Escherichia coli (Escherichia genus), Enterococcus (Salmonella genus), Pseudomonas aeruginosa (Pseudomonas genus)) were selected for testing. The results showed that the IC values of the compounds of the present invention against the representative strains were 0.1% and 0.2%, respectively. 50 The values (μg / mL) were: Staphylococcus aureus 3.88, beta-hemolytic Streptococcus 8.06, Streptococcus pneumoniae 4.95, Escherichia coli 3.22, Enterococcus 4.90, Pseudomonas aeruginosa 6.18. The compound has significant antibacterial activity and broad antibacterial spectrum.

[0067] B. Tyrosinase Inhibition Activity Testing of Compounds: Since tyrosinase is a key enzyme involved in melanin synthesis in the skin, modulating its activity can achieve a whitening effect. The tyrosinase inhibition activity of the benzo[g]chromone compounds was further tested. Specific testing procedures were described in the "Cosmetics - Tyrosinase Inhibition Test Method (T / ZHCA 001-2018)." The results demonstrated that the benzo[g]chromone compounds exhibited significant tyrosinase inhibition activity, with an inhibition rate of 58.6% at a concentration of 50 μg / mL.

[0068] C. Determination of the Sunscreen Properties of the Compounds: Benzo[g]chromone compounds have a large conjugated system and exhibit strong UV absorption, so their sunscreen properties were determined. The test was conducted according to the "Qualitative Determination of Ultraviolet Absorbers in Cosmetics - Ultraviolet Spectrophotometric Method (QB / T 2334-1997)." The test results indicate that the benzo[g]chromone exhibits strong UV absorption in both the UVB region (280-320 nm) and the UVA region (320-400 nm), with molar absorptivity greater than 3.2×10-1 within these wavelength ranges. 3 Since ultraviolet rays in the UVA and UVB regions can cause the skin to become red, tanned, or even damaged in severe cases, the benzo[ g ]The strong ultraviolet absorption of chromone in this wavelength range confirms that the compound has a significant sunscreen effect.

[0069] D. Application effect of compound whitening skin cream: Referring to the formula design ideas of whitening skin cream, the basic formula of skin cream selects olive oil, medical vaseline, paraffin oil, hexadecanol (cetyl alcohol), octadecyl alcohol, etc. as the oil phase; deionized water (distilled water), cyclodextrin, propylene glycol, tartaric acid, citric acid, etc. as the aqueous phase, supplemented with sodium carboxymethyl cellulose and polyvinyl alcohol for thickening; then monostearate glyceryl, sodium stearate, lanolin and SE emulsifier are used to adjust the hydrophilic-lipophilic balance value and water content; then physical additives (titanium dioxide, pearl powder, calcium carbonate), moisturizers (allantoin, glycerin), antioxidants (cod liver oil, VC, VE), natural essential oils (rose essential oil, lavender essential oil, jasmine essential oil, etc.) are added for fragrance, and the benzo[g]chromone extract of the present invention is used as an antibacterial, whitening and UV protection additive. The specific formula proportions (by mass%) are: 2.0% olive oil, 12.0% medical petrolatum, 4.0% paraffin oil, 1.0% cetyl alcohol, 0.8% stearyl alcohol; 2.0% cyclodextrin, 5.0% propylene glycol, 0.1% tartaric acid, 0.1% citric acid, 0.2% polyvinyl alcohol; 2.0% glyceryl monostearate, 0.8% sodium stearate, 1.2% lanolin, 1.2% SE emulsifier, 0.2% titanium dioxide, 2.0% vitamin E, 0.05% vitamin E, 0.1% natural essential oil (0.1-0.3%, adjusted according to the desired fragrance), 0.2% benzo[g]chromone described in this invention, and the balance water. The formulated whitening skin cream was tested by a professional testing agency using the brown guinea pig skin test method. The results showed that the inhibition rate of melanocytes and melanocytes was over 46.5%. The skin care acid with the same formula but without the benzo[g]chromone compound was used as a control, and the inhibition rate of the control on melanocytes and melanocytes was above 45.6%.

[0070] Example 5

[0071] The antibacterial active benzo[g]chromone compounds prepared in Example 2 and Example 3 were tested respectively using the same method as Example 4. The results showed that the antibacterial active benzo[g]chromone compounds described in the present invention have significant antibacterial activity, broad-spectrum antibacterial activity, tyrosinase inhibitory activity, sun protection effect and whitening effect.

Claims

1. A benzo[g]chromone compound having antibacterial activity, characterized in that: The benzo[g]chromone compound with antibacterial activity is prepared from the whole plant of the medicinal plant Cassia torafolia by pretreatment, extract extraction, MCI decolorization, silica gel column chromatography, and high-performance liquid chromatography separation. It is named: 6-methoxy-2,9-dimethylbenzo[2,3-g]-4H-chromone, and its English name is: 6-methoxy-2,9-dimethylbenzo [2,3-g]-4H-chromone, and has the following structure: 。 2. A method for preparing the benzo[g]chromone compound with antibacterial activity according to claim 1, characterized in that: The preparation method is prepared from the whole plant of the medicinal plant Cassia obtusifolia as raw material through pretreatment, organic solvent extraction, MCI decolorization, silica gel column chromatography and high performance liquid chromatography separation, specifically comprising the following steps: A. Pretreatment: crush or cut the whole plant of the raw medicinal plant Cassia tora into segments to obtain material a; B. Organic solvent extraction: Add 2 to 6 times the mass of organic extraction solvent to material a, soak and extract 2 to 5 times at room temperature, each extraction time is 12 to 20 hours, combine the extracts and filter to obtain sample extract b; C. MCI decolorization: The sample extract was decolorized on an MCI column, the effluent was collected and concentrated under reduced pressure to obtain extract C; D. Silica gel column chromatography: 1) Add 200-250 mesh silica gel in an amount 3-10 times the weight of extract C to the column, and perform gradient elution with a chloroform-methanol solution in a volume ratio of 20:1 to 1:

1. Monitor by TLC and combine the same fractions. 2) The 9:1 chloroform-methanol eluate was concentrated under reduced pressure to obtain fraction d. A 200-250 mesh silica gel column was loaded with 3-10 times the weight of the obtained fraction d. Gradient elution was performed with a 1:0-1:2 volume ratio of chloroform-acetone solution. The eluate was monitored by TLC and the same fractions were combined. E. High Performance Liquid Chromatography Separation: The eluate obtained by eluting with a chloroform-acetone solution in a ratio of 8:2 was separated and purified by high performance liquid chromatography to obtain the target benzo[g]chromone compounds with antibacterial activity.

3. The preparation method according to claim 2, characterized in that The organic extraction solvent in step B is a methanol aqueous solution with a mass concentration of 70% to 100%, an ethanol aqueous solution with a mass concentration of 70% to 100%, or an acetone aqueous solution with a mass concentration of 70% to 100%.

4. The preparation method according to claim 2, characterized in that Step D also includes a sample mixing step before loading onto the column, wherein the material C is dissolved in an organic solvent at a volume of 1.5 to 3 times the weight of the material C and then 0.8 to 2.0 times the weight of the material C is added with 80 to 100 mesh silica gel.

5. The preparation method according to claim 2, characterized in that The organic extraction solvent is pure methanol or pure acetone.

6. The preparation method according to claim 2, characterized in that D. The volume ratios of the chloroform-methanol solution described in step 1) are 20:1, 9:1, 8:2, 7:3, 6:4 and 1:

1.

7. The preparation method according to claim 2, characterized in that In step E, the high performance liquid chromatography separation and purification uses a methanol aqueous solution with a volume concentration of 55-62% as the mobile phase, a flow rate of 12 mL / min, a 2.12×250 mm, 5 μm Zorbax PrepHT GF reverse phase preparative column as the stationary phase, an ultraviolet detector with a detection wavelength of 364 nm, 0.5~1.0 mL is injected each time, and the chromatographic peak of 28~35 min is collected. After multiple accumulation, the target antibacterial active benzo[g]chromone compound is evaporated to dryness.

8. A use of the benzo[g]chromone compound with antibacterial activity according to claim 1, characterized in that: The application of the antibacterial active benzo[g]chromone compounds in the preparation of cosmetic additives.

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