A highly effective antibacterial hydroxy acid ester oligomer

Abstract

The present invention discloses a highly effective antibacterial hydroxy acid ester oligomer. The general structural formula of the hydroxy acid ester oligomer proposed in the present invention is Formula (I). Starting from molecular structural design, the present invention rationally designs the end groups and chain length structure of the substance of Formula (I), and controls its clogP value to achieve an appropriate size of the substance of Formula (I). This maximizes and synergistically improves the ability of the substance of Formula (I) to penetrate into bacteria and destroy bacterial cell membranes, thereby achieving the purpose of highly effective antibacterial properties. Furthermore, by precisely designing the molecular structure and regulating the hydrophilicity and hydrophobicity of the hydroxy acid ester oligomer, a bio-based antibacterial agent with controllable water solubility is obtained.

Description

[0001] This application is a divisional application of the invention patent application with application number 202111137059.1, application date September 27, 2021, and name “A highly effective antibacterial hydroxy acid oligomer”. Technical Field

[0002] The present invention belongs to the field of biomedicine, and in particular relates to a highly effective antibacterial hydroxy acid ester oligomer. Background Art

[0003] Antimicrobial agents are substances that can suppress the growth or reproduction of certain microorganisms (such as bacteria, fungi, yeasts, algae, and viruses) for a specified period of time. They are widely used in textiles, plastics, detergents, medical products, and other fields.

[0004] As people's living standards continue to improve, the demand for hygiene in textiles and various household plastics is also increasing. The continuous improvement of the natural and environmentally friendly standards for antimicrobial products has important practical value in improving my country's health care level and reducing cross-infection in the public environment. Therefore, the research on natural, safe, and efficient bio-based antimicrobial agents is imperative.

[0005] Chinese patent CN 110452115 A discloses a poly 3-hydroxybutyrate oligomer, which is used to prepare antibacterial materials. Its minimum inhibitory concentration (MIC, in mg / mL) is as follows:

[0006]

[0007] The antimicrobial activity of these oligomers is insufficient to meet the growing demand for performance in antimicrobial products. Furthermore, their water solubility cannot be controlled, limiting their application range. Furthermore, their synthesis process uses expensive, non-biobased butyrolactone as a raw material, along with toxic catalysts and solvents, resulting in complex post-processing.

[0008] Because bacteria have highly organized cell membranes, they can effectively resist the binding and penetration of foreign invading molecules. Therefore, the rational design of antimicrobial agents that effectively penetrate and disrupt bacterial cell membranes is of great significance. Through extensive research, the inventors have discovered that leveraging the synergistic effects of the end groups and chain lengths of hydroxy acid ester oligomers can effectively enhance the efficiency of antimicrobial agents in penetrating and disrupting bacterial cell membranes, thereby achieving highly effective antibacterial properties and further enabling controllable water solubility. Summary of the Invention

[0009] The purpose of the present invention is to provide a highly effective antibacterial substance, R-(-)-hydroxy acid ester oligomer, based on the development demand for natural and environmentally friendly antibacterial agents.

[0010] The antibacterial substance R-(-)-hydroxy acid ester oligomer of the present invention has a pH value close to neutral and its general structural formula is as follows (I):

[0011]

[0012] wherein n is a natural number of 1-8, i.e., the degree of polymerization DP is 1-8; R1 is a C1-C5 alkyl group, preferably a C1-C2 alkyl group; R2 is a C2-C8 alkyl group, preferably a C5-C6 alkyl group; m is a natural number of 0-3, preferably m is 0 or 1;

[0013] Preferably, the clogP value of the highly effective antibacterial hydroxy acid ester oligomer satisfies 1.5-3.0; more preferably, 2.0-2.5;

[0014] Preferably, the general structural formulas of the highly effective antibacterial hydroxy acid ester oligomers are as follows:

[0015]

[0016] Preferably, when n=1-3 in the general structural formula (I), R1 is a C1-C5 alkyl group, R2 is a C2-C3 alkyl group, and m=0-3, the R-(-)-hydroxy acid ester oligomer is a water-soluble substance; when n=1-3 in the general structural formula (I), R1 is a C1-C5 alkyl group, R2 is a C4-C8 alkyl group, and m=0-3, the R-(-)-hydroxy acid ester oligomer is a water-insoluble substance and is soluble in various organic solvents (such as ethanol, n-butanol, dimethyl sulfoxide, acetone, and diethyl ether); when n=4-8 in the general structural formula (I), R1 is a C1-C5 alkyl group, R2 is a C2-C8 alkyl group, and m=0-3, the R-(-)-hydroxy acid ester oligomer is a water-insoluble substance and is soluble in various organic solvents (such as ethanol, n-butanol, dimethyl sulfoxide, acetone, and diethyl ether);

[0017] Preferably, the general structural formula of the water-soluble antibacterial substance R-(-)-hydroxy acid ester oligomer is as follows:

[0018]

[0019] Where n = 2-3;

[0020] Preferably, the general structural formula of the water-insoluble antibacterial substance R-(-)-hydroxy acid ester oligomer is as follows:

[0021]

[0022] Wherein n=4-8.

[0023] The beneficial effects of the present invention are:

[0024] 1. The present invention starts from the molecular structure design, through the rational design of the end group and chain length structure of the substance of formula (I), and by controlling its clogP value, so that the substance of formula (I) of the present invention reaches an appropriate size, thereby maximizing the synergistic improvement of the ability of the substance of formula (I) to penetrate into the interior of bacteria and destroy bacterial cell membranes, thereby achieving the purpose of high-efficiency antibacterial effect.

[0025] 2. The present invention obtains a bio-based antibacterial agent with controllable water solubility by precisely designing the molecular structure and regulating the hydrophilicity and hydrophobicity of R-(-)-hydroxy acid ester oligomers, thereby broadening its scope of application. For example, in the fields of food, medicine, cosmetics, etc., antibacterial agents with good water solubility, ease of use, and uniform dispersion of substances in water are required. Water-soluble hydroxy acid ester oligomers can better meet these requirements. On the other hand, in the fields of coatings, fibers, plastics, building materials, etc., antibacterial agents that are resistant to water washing are required to ensure a longer-lasting antibacterial effect. At this time, only water-insoluble hydroxy acid ester oligomers can meet these requirements.

[0026] 3. The raw materials used in the present invention are all bio-based raw materials, which are convenient and easy to obtain; the synthesis process avoids the use of toxic catalysts and solvents, avoids complicated post-processing, and the catalyst is recyclable, which is easier to scale up and produce, and is also conducive to meeting environmental protection requirements and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the mass spectrometry analysis result of the water-soluble R-(-)-3-hydroxybutyric acid ethyl ester oligomer in Example 1-1.

[0028] Figure 2 This is the mass spectrometry analysis result of the water-insoluble R-(-)-3-hydroxybutyric acid ethyl ester oligomer in Example 1-2.

[0029] Figure 3 This is the NMR spectrum of R-(-)-3-hydroxybutyric acid hexyl ester.

[0030] Figure 4 This is the NMR spectrum of R-(-)-2-hydroxyhexyl propionate. DETAILED DESCRIPTION

[0031] The technical solutions and effects of the present invention are further described below in conjunction with the embodiments. However, the present invention is not limited to the substances, proportions and methods shown in the embodiments. Any changes that can be easily associated with the material combinations and methods shown in these embodiments by a person skilled in the art are within the scope of protection of the present invention.

[0032] Example 1: Synthesis of R-(-)-3-Hydroxybutyrate Ethyl Ester Oligomer

[0033] Example 1-1

[0034] In a three-necked flask, 10 g of ethyl 3-hydroxybutyrate and 0.01 g of zinc acetate (i.e., 0.1% by mass of ethyl 3-hydroxybutyrate) were added, respectively, accompanied by mechanical stirring, a thermometer, and a distillation apparatus. The stirring speed was slow, about 150 rpm, and the temperature was raised to 150°C at 0.5-3°C / min in a trace nitrogen environment for 1 hour. The reaction was stopped to obtain 3-HB oligomers, and their polymerization degree was detected by mass spectrometry. The antibacterial experiment referred to "GB / T 20944.3-2008 Evaluation of Antibacterial Properties of Textiles Part 3: Oscillation Method". The strain was Escherichia coli ATCC 25922.

[0035] Examples 1-2 to 1-3

[0036] According to Table 1, the catalyst type and reaction temperature were changed on the basis of Example 1-1. Other conditions were the same as those in Example 1-1 to obtain R-(-)-3-hydroxybutyric acid ethyl ester oligomers with different polymerization degrees.

[0037] Table 1 Experimental conditions and product parameters of Examples 1-1 to 1-3

[0038]

[0039] Figure 1 This is the mass spectrometry analysis result of the water-soluble R-(-)-3-hydroxybutyric acid ethyl ester oligomer in Example 1-1.

[0040] Figure 2 This is the mass spectrometry analysis result of the water-insoluble R-(-)-3-hydroxybutyric acid ethyl ester oligomer in Example 1-2.

[0041] Example 2: Synthesis of R-(-)-3-hydroxybutyrate monomer (n=1)

[0042] Example 2-1

[0043] In a three-necked flask, 1 mol of R-(-)-3-hydroxybutyric acid, 10 mol of methanol, 5.2 g of catalyst p-toluenesulfonic acid (0.15% by mass of R-(-)-3-hydroxybutyric acid), and a water-carrying agent of n-hexane in an amount of 50% by volume of the alcohol were added. Under stirring, the temperature was slowly raised to 150°C and kept for 8 hours. The reaction was stopped and cooled to room temperature. The remaining alcohol and n-hexane were removed by vacuum distillation at 90°C and 5000 Pa. The temperature was then raised to 150°C and the reduced pressure was <1000 Pa. The distillate was collected. The distillate was methyl 3-hydroxybutyrate with a yield of 93%.

[0044] Examples 2-2 to 2-8

[0045] In Examples 2-2 to 2-8, methanol was replaced with ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol, respectively, based on Example 2-1. Other experimental conditions were consistent with those in Example 2-1, and R-(-)3-hydroxybutyric acid ethyl ester (yield 95%), R-(-)3-hydroxybutyric acid propyl ester (yield 93%), R-(-)3-hydroxybutyric acid butyl ester (yield 92%), R-(-)3-hydroxybutyric acid pentyl ester (yield 94%), R-(-)3-hydroxybutyric acid hexyl ester (yield 96%), R-(-)3-hydroxybutyric acid heptyl ester (yield 95%), and R-(-)3-hydroxybutyric acid octyl ester (yield 94%) were obtained, respectively. The purity detected by gas phase was approximately 100%.

[0046] Figure 3 This is the NMR spectrum of R-(-)-3-hydroxybutyric acid hexyl ester.

[0047] The R-(-)-3-hydroxybutyric acid ethyl ester oligomers and R-(-)-3-hydroxybutyric acid hexyl ester oligomers prepared in Examples 1-2 and 2-6 were tested by the Guangdong Provincial Microbiological Analysis and Testing Center. The testing basis and method were: "Technical Specifications for Disinfection" 2002 edition of the Ministry of Health - 2.1.8.4 Minimum Inhibitory Concentration Test (Nutrient Broth Method). The results are shown in Table 2.

[0048] Table 2. Minimum inhibitory concentrations of R-(-)-3-hydroxybutyric acid ethyl oligomers and R-(-)-3-hydroxybutyric acid hexyl oligomers for different strains

[0049]

[0050] Examples 2-9

[0051] Based on Example 2-1, R-(-)-3-hydroxybutyric acid was changed to R-(-)-3-hydroxypropionic acid, methanol was changed to 1-hexanol, and other experimental conditions were kept consistent with Example 2-1 to obtain R-(-)-2-hydroxypropionic acid hexyl ester.

[0052] Figure 4 This is the NMR spectrum of R-(-)-2-hydroxyhexyl propionate.

[0053] R-(-)3-hydroxybutyric acid methyl ester NMR experimental data, the spectrum is assigned as follows: 1 H NMR (CDCl3): 4.33 (m, H), 3.72 (s, 3H), 2.53 (q, 2H), 1.21 (d, 3H)

[0054] R-(-)3-Hydroxybutyrate NMR experimental data, the spectrum is assigned as follows: 1H NMR (CDCl3): 4.33 (m, H), 4.01 (m, 2H), 2.41 (m, 2H), 1.15 (m, 6H)

[0055] R-(-)3-Hydroxybutyric Acid Propyl NMR experimental data, the spectrum is attributed as follows: 1 H NMR (400MHz, Chloroform-d) δ4.28 -4.16(m,1H),4.10(t,2H),2.59-2.40(m,2H),1.76-1.64(m,2H),1.26(dd,3H),0.97(t,3H).

[0056] R-(-) 3-Hydroxybutyrate NMR experimental data, the spectrum is attributed as follows: 1 H NMR(400MHz,Chloroform-d)δ4.48–4.39(m,2H),4.33(ddt,4H),2.78-2.55(m ,4H),1.84(tdd,4H),1.69-1.52(m,4H),1.49-1.39(m,6H),1.21-1.09(m,6H).

[0057] R-(-)pentyl 3-hydroxybutyrate NMR experimental data, the spectrum is assigned as follows: 1H NMR (CDCl3): 4.23 (m, H), 4.14 (t, 2H), 2.43 (m, 2H), 1.67 (m, 2H), 1.37 (m, 4H), 1.26 (d, 3H), 0.95 (m, 3H)

[0058] R-(-)3-Hydroxybutyric acid hexyl ester NMR experimental data, the spectrum is attributed as follows: 1 H NMR(400MHz,Chloroform-d)δ4.29–4.18(m,1H),4.14(t,2H),2.58-2.40(m,2H),1.73-1.61(m,2H),1.44-1.29(m,6H),1.26(d,3H),0.97-0.89(m,3H).

[0059] R-(-) 3-Hydroxybutyrate NMR experimental data, the spectrum is attributed as follows: 1 H NMR(400MHz,Chloroform-d)δ4.23(dqd,1H),4.14(t,2H),2.53(dd,1H),2.50-2.40(m,1H),1.67(t,2H),1.43-1.29(m,9H),1.27(dd,3H),0.92(t,3H).

[0060] R-(-) 3-Hydroxybutyrate NMR experimental data, the spectrum is attributed as follows: 1 H NMR (400MHz, Chloroform-d) δ4.23(t,1H),4.15(t,3H),2.54(dd,1H),2.46(dd,1H),1.74-1.62(m,3H),1.42-1.24(m,18H),0.92(t,4H).

[0061] Example 3: Synthesis of R-(-)-lactate monomer (n=1)

[0062] Example 3-1

[0063] In Example 2-1, R-(-)-3-hydroxybutyric acid was replaced with R-(-)-lactic acid, and methanol was replaced with 1-hexanol. Other conditions were the same as in Example 2-1, and R-(-)-hexyl lactate was prepared with a yield of 94% and a purity of about 100% as determined by gas phase analysis.

[0064] Examples 3-2 to 3-3

[0065] In Examples 3-2 to 3-3, 1-hexanol was replaced with ethanol and 1-heptanol respectively based on Example 3-1. Other conditions were the same as in Example 3-1, and R-(-)-ethyl lactate and R-(-)-heptyl lactate were obtained respectively, with a purity of about 100% by gas phase detection.

[0066] Example 4: Synthesis of R-(-)-2-Hydroxyhexyl Propionate

[0067] Example 3-1 Based on Example 3-1, R-(-)-lactic acid was replaced with R-(-)-2-hydroxypropionic acid to obtain R-(-)-2-hydroxypropionic acid hexyl ester, and the purity detected by gas phase was about 100%.

[0068] R-(-)-2-Hydroxypropionic acid hexyl ester NMR experimental data, the spectrum is attributed as follows: 1 H NMR (CDCl3): 4.29 (m, H), 1.60 (m, 2H), 1.42 (m, 9H), 0.88 (m, 3H)

[0069] The products of Examples 2-3 were subjected to antibacterial testing and clogP theoretical calculations, see Table 3.

[0070] Table 3. Antibacterial experimental data of hydroxy acid ester oligomers

[0071]

[0072]

[0073] Note: clogP represents the logarithm of the partition coefficient of a substance between lipid and water phases. The data were theoretically estimated using the ChemDrawUltra 13.0 program. Antibacterial test method: Test basis and method: Ministry of Health 2002 edition "Technical Specifications for Disinfection" - 2.1.8.4 Minimum Inhibitory Concentration Test (Nutrient Broth Method), where the bacterial species selected was Escherichia coli ATCC 25922.

[0074] As can be seen from Table 2, the clogP value of the hydroxy acid ester oligomer prepared by the present invention increases regularly with the ester chain length, but when the clogP value is around 2.4, the best antibacterial effect (MIC is 1.95 mg / mL) is achieved. Therefore, when clogP = 2.4, the molecular size of R-(-)-hydroxy acid ester is most suitable, allowing it to insert into the cell membrane, destroy the stable structure of the cell membrane phospholipid bilayer, and achieve a highly effective antibacterial effect.

[0075] It should be noted that the specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. Use of an oligomer having a general structural formula (V) in the preparation of an antibacterial agent, characterized in that: The antibacterial agent is an agent that inhibits Candida albicans ATCC 10231; Wherein, the oligomer of formula (V) is: Wherein n=4-8.

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