Method for preparing phytosterol derivative through multi-element catalysis

Abstract

The invention discloses a method for preparing a phytosterol derivative through multi-element catalysis, and relates to the field of multi-element catalysis. The method for preparing the phytosterol derivative through multi-element catalysis comprises the following steps: S1, mixing fatty acid methyl ester, phytosterol and a first catalyst, and carrying out heating and decompression reaction to obtain a first product; s2, mixing the first product and a second catalyst, and carrying out heating reaction to obtain a second product; s3, performing reverse osmosis membrane separation and purification on the second product to obtain the phytosterol derivative, wherein the first catalyst is lipase and aluminum oxide which are loaded on an immobilization carrier, the immobilization carrier comprises chitosan, sodium alginate or silica gel, and the second catalyst is sodium methoxide. The method for preparing the phytosterol derivative through multi-element catalysis is short in preparation time and high in finished product purity.

Description

Technical Field

[0001] The present invention relates to the field of multi-component catalysis, and in particular to a method for preparing phytosterol derivatives through multi-component catalysis. Background Art

[0002] Phytosterol derivatives are a class of natural compounds with unique chemical structures and significant physiological activities. They competitively inhibit cholesterol absorption in the human body, effectively lowering serum cholesterol levels and playing a vital role in preventing and improving cardiovascular disease. In the industrial sector, phytosterol derivatives, due to their excellent emulsification, dispersion, and stability, offer broad application prospects in the food, pharmaceutical, and cosmetics industries. For example, in the food industry, they can be added as nutritional supplements to dairy products, edible oils, and other products; in the pharmaceutical field, they can be used to prepare lipid-lowering and anti-inflammatory drugs; and in the cosmetics industry, they offer moisturizing, hydrating, and antioxidant properties.

[0003] However, in the current synthesis reactions of industrial plant sterol derivatives, although the process conditions for chemical synthesis of plant sterol derivatives are relatively simple, the reaction temperature is usually high, and side reactions are prone to occur, resulting in reduced product purity and yield; enzyme-catalyzed synthesis has the advantages of mild reaction conditions, high selectivity, and few side reactions, but the enzyme is expensive, resulting in high production costs. Summary of the Invention

[0004] The present invention is made in view of the above-mentioned problems and provides a method for preparing phytosterol derivatives by multi-component catalysis.

[0005] The first aspect of the present invention provides a method for preparing plant sterol derivatives by multi-catalysis, comprising the following steps: S1, mixing fatty acid methyl ester, plant sterol and a first catalyst, heating and reducing pressure to react, to obtain a first product; S2, mixing the first product and a second catalyst, heating and reacting to obtain a second product; S3, subjecting the second product to reverse osmosis membrane separation and purification to obtain a plant sterol derivative; wherein the first catalyst is lipase and alumina supported on an immobilized carrier, the immobilized carrier includes chitosan, sodium alginate or silica gel, and the second catalyst is sodium methoxide.

[0006] In some embodiments of the present invention, the phytosterol includes one of brassicasterol, stigmasterol, β-sitosterol, and avenasterol.

[0007] In some embodiments of the present invention, the phytosterol derivative comprises at least one of sterol esters, sterol glycosides, and acylsterol glycosides.

[0008] In some embodiments of the present invention, the mass ratio of the first catalyst, the second catalyst and the phytosterol is 0.5:(2-3):(80-110).

[0009] In some embodiments of the present invention, the mass ratio of the immobilized carrier, the lipase and the alumina is 1:(0.1-0.2):(0.05-0.15).

[0010] In some embodiments of the present invention, the mass ratio of the fatty acid methyl ester to the phytosterol is (1-1.5):1.

[0011] In some embodiments of the present invention, in step S1, the temperature of the temperature-raising and pressure-reducing reaction is 100°C to 120°C, the pressure of the temperature-raising and pressure-reducing reaction is -0.055MPa to -0.075MPa, and the reaction time of the temperature-raising and pressure-reducing reaction is 1 to 2h.

[0012] In some embodiments of the present invention, in step S2, the temperature of the temperature-elevating reaction is 120° C. to 130° C., and the reaction time of the temperature-elevating reaction is 30 min to 60 min.

[0013] In some embodiments of the present invention, in step S3, when the reverse osmosis membrane is used to separate and purify sterol esters, its molecular weight cut-off is 200Da to 300Da.

[0014] In some embodiments of the present invention, the reverse osmosis membrane separation and purification has an operating pressure of 300psi to 400psi and an operating temperature of 40°C to 45°C.

[0015] The beneficial effects that can be achieved by the present invention are:

[0016] The present invention provides a method for preparing plant sterol derivatives through multi-catalysis. Two different catalysts are used. Lipase has high stereoselectivity and can accurately catalyze the ester exchange reaction between fatty acid methyl esters and plant sterols. Alumina further improves the reaction rate and conversion rate. The high selectivity of lipase and alumina work together to avoid the occurrence of side reactions. Sodium methoxide is then used as a second catalyst to form a two-stage catalysis, covering different reaction mechanisms, improving the purity and yield of the product, and also having the advantages of solvent reduction and less waste. DETAILED DESCRIPTION

[0017] The following description is provided to enable those skilled in the art to fully understand the present invention, and is not intended to limit the subject matter described in the claims.

[0018] The "ranges" disclosed herein are defined in terms of lower and upper limits, where a given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the end values and may be combined arbitrarily, i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In the present invention, unless otherwise indicated, the numerical range "a to b" is a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0019] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0020] Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0021] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0022] In the current synthesis reactions of industrial plant sterol derivatives, although the process conditions for chemical synthesis of plant sterol derivatives are relatively simple, the reaction temperature is usually high, and side reactions are prone to occur, resulting in reduced product purity and yield; enzyme-catalyzed synthesis has the advantages of mild reaction conditions, high selectivity, and few side reactions, but the enzyme is expensive, resulting in high production costs.

[0023] In view of this, this solution proposes a method for preparing phytosterol derivatives by multi-catalysis, which is characterized by comprising the following steps:

[0024] S1, mixing fatty acid methyl ester, phytosterol and a first catalyst, heating and reducing pressure to react, to obtain a first product;

[0025] S2, mixing the first product and the second catalyst and heating the mixture to react to obtain a second product;

[0026] S3, separating and purifying the second product through a reverse osmosis membrane to obtain a phytosterol derivative;

[0027] The first catalyst is lipase and alumina loaded on an immobilized carrier, the immobilized carrier comprises chitosan, sodium alginate or silica gel, and the second catalyst is sodium methoxide.

[0028] This scheme uses two different catalysts. The high stereoselectivity of lipase is utilized to accurately catalyze the transesterification reaction between fatty acid methyl esters and plant sterols. Alumina further improves the reaction rate and conversion rate. The high selectivity of lipase and alumina work together to avoid the occurrence of side reactions. Sodium methoxide is then used as the second catalyst to form a two-stage catalysis, covering different reaction mechanisms, improving the purity and yield of the product, and also has the advantages of reducing solvent and waste.

[0029] In some embodiments, the immobilized lipase carrier has a high specific surface area, and the catalytic efficiency of the loaded enzyme is higher than that of the free enzyme. The immobilized lipase carrier is preferably chitosan, which has good biocompatibility and chemical stability, is more compatible with the polarity of the fatty acid methyl ester and phytosterol mixture, and facilitates the dispersion of the lipase catalyst. The amino functional groups on the surface of the chitosan carrier can stabilize the enzyme conformation, ensuring good activity retention after repeated use.

[0030] In some embodiments, the material and permeability of the reverse osmosis membrane are selected based on the specific type of phytosterol derivatives, such as polyamide (PA) composite membrane, polyacrylonitrile (PAN) membrane, polysulfone (PS) and polyamide composite membrane, etc.

[0031] In some embodiments, the phytosterol comprises one of: brassicasterol, stigmasterol, β-sitosterol, and avenasterol. This solution has better performance in the catalytic esterification reaction of β-sitosterol or avenasterol raw materials.

[0032] In some embodiments, the phytosterol derivative comprises at least one of a sterol ester, a sterol glycoside, and an acyl sterol glycoside. This solution exhibits superior performance in the catalytic esterification of β-sitosterol or avenasterol, i.e., the efficiency of catalytically preparing sterol esters is higher than that of the other two derivatives.

[0033] In some embodiments, the mass ratio of the first catalyst, the second catalyst, and the phytosterol is 0.5:(2-3):(80-110). Due to the reduced amount of enzyme used, the enzyme procurement cost in the production cost is directly reduced. After the first stage of catalysis is completed, sodium methoxide promotes further transesterification of unreacted fatty acid methyl esters under alkaline conditions.

[0034] In some embodiments, the mass ratio of the immobilized carrier, the lipase, and the alumina is 1:(0.1-0.2):(0.05-0.15). Alumina adsorbs free fatty acids (FFA) generated during the reaction to reduce product inhibition.

[0035] In some embodiments, the mass ratio of the fatty acid methyl ester to the phytosterol is (1-1.5):1. The fatty acid methyl ester, as one of the reactants, can also act as a solvent to dissolve the phytosterol. In addition, the immobilized lipase of this solution has high activity in a solvent-free system, and the carrier (such as chitosan or silica gel) has good dispersibility in the oil phase.

[0036] In some embodiments, in step S1, the temperature of the temperature-elevated pressure-reduced reaction is 100° C. to 120° C., the pressure of the temperature-elevated pressure-reduced reaction is -0.055 MPa to -0.075 MPa, and the reaction time of the temperature-elevated pressure-reduced reaction is 1 to 2 hours. The reduced pressure condition can lower the boiling point of the reaction system, allowing the reaction to proceed at a lower temperature, thereby avoiding the adverse effects of high temperature on the catalyst and reactants, such as catalyst deactivation and reactant decomposition, and improving the reaction conversion rate and product yield.

[0037] In some embodiments, in step S2, the temperature of the temperature-elevated reaction is 120° C. to 130° C., and the reaction time of the temperature-elevated reaction is 30 to 60 minutes. In the short reaction time of 30 to 60 minutes, the activity of the sodium methoxide catalyst can be fully utilized. The shortened reaction time means that more reaction batches can be completed per unit time, thereby improving production efficiency.

[0038] In some embodiments, in step S3, when the reverse osmosis membrane is used to separate and purify sterol esters, its molecular weight cut-off is 200Da to 300Da. Reverse osmosis membrane separation technology is a physical separation method that does not require the addition of large amounts of chemical reagents or complex chemical reactions, and the operation process is relatively simple. It is only necessary to pass the reacted mixture through a reverse osmosis membrane and separate it under a certain pressure, which is easy to achieve automated and continuous production. Compared with traditional separation methods such as distillation and extraction, reverse osmosis membrane separation technology has lower energy consumption and does not require the use of large amounts of organic solvents, reducing the consumption of raw materials and the cost of waste treatment.

[0039] In some embodiments, the reverse osmosis membrane separation and purification operates at a pressure of 300 psi to 400 psi and a temperature of 40° C. to 45° C. Within the temperature range of 40° C. to 45° C., the viscosity of the solvent can be reduced, thereby increasing the permeation rate of the membrane without causing thermal damage to the membrane material.

[0040] The technical solutions of the present invention are further described in detail below in conjunction with specific embodiments. It should be understood that the following specific embodiments are only used to explain the present invention and are not used to limit the present invention.

[0041] Example 1

[0042] 120 g of fatty acid methyl ester, 100 g of β-sitosterol, 0.46 g of lipase supported on chitosan (0.4 g of chitosan, 0.06 g of lipase), and 0.04 g of alumina were mixed, heated to 110° C. and reacted under reduced pressure of −0.065 MPa for 1 hour to obtain the first product;

[0043] The first product was mixed with 2.5 g of sodium methoxide and reacted at 125° C. for 45 min to obtain the second product;

[0044] The second product was separated and purified using a reverse osmosis membrane with a molecular weight cut-off of 300 Da at 350 psi and 42° C. to obtain β-sitosterol fatty acid ester.

[0045] Example 2

[0046] 120 g of fatty acid methyl ester, 90 g of stigmasterol, 0.46 g of lipase supported on chitosan (0.4 g of chitosan, 0.06 g of lipase), and 0.04 g of alumina were mixed, heated to 110° C. and reacted under reduced pressure of −0.065 MPa for 1 hour to obtain the first product;

[0047] The first product was mixed with 2.5 g of sodium methoxide and reacted at 125° C. for 45 min to obtain the second product;

[0048] The second product was separated and purified using a reverse osmosis membrane with a molecular weight cut-off of 300 Da at 350 psi and 42° C. to obtain stigmasterol ester.

[0049] Example 3

[0050] 120 g of fatty acid methyl ester, 100 g of avenasterol, 0.46 g of lipase supported on chitosan (0.4 g of chitosan, 0.06 g of lipase), and 0.04 g of alumina were mixed, heated to 110° C. and reacted under reduced pressure of −0.065 MPa for 1 hour to obtain the first product;

[0051] The first product was mixed with 2.5 g of sodium methoxide and reacted at 125° C. for 45 min to obtain the second product;

[0052] The second product was separated and purified using a reverse osmosis membrane with a molecular weight cut-off of 300 Da at 350 psi and 42° C. to obtain avenantosterol esters.

[0053] Example 4

[0054] 150 g of fatty acid methyl ester, 110 g of rapeseed sterol, 0.46 g of lipase supported on silica gel (0.4 g of silica gel, 0.06 g of lipase), and 0.04 g of alumina were mixed, heated to 110° C. and reacted under reduced pressure of −0.065 MPa for 2 hours to obtain a first product;

[0055] The first product and 2 g of sodium methoxide were mixed and reacted at 125° C. for 45 min to obtain the second product;

[0056] The second product was separated and purified using a reverse osmosis membrane with a molecular weight cut-off of 300 Da at 350 psi and 42° C. to obtain rapeseed sterol esters.

[0057] Example 5

[0058] 125 g of fatty acid methyl ester, 90 g of rapeseed sterol, 0.46 g of lipase supported on silica gel (0.4 g of silica gel, 0.06 g of lipase), and 0.04 g of alumina were mixed, heated to 110° C. and reacted under reduced pressure of −0.065 MPa for 1 hour to obtain a first product;

[0059] The first product was mixed with 2.5 g of sodium methoxide and reacted at 125° C. for 45 min to obtain the second product;

[0060] The second product was separated and purified using a reverse osmosis membrane with a molecular weight cut-off of 300 Da at 350 psi and 42° C. to obtain β-sitosterol fatty acid ester.

[0061] Example 6

[0062] 130 g of fatty acid methyl ester, 110 g of β-sitosterol, 0.46 g of lipase supported on silica gel (0.4 g of silica gel, 0.06 g of lipase), and 0.04 g of alumina were mixed, heated to 110° C. and reacted under reduced pressure of −0.065 MPa for 1 hour to obtain a first product;

[0063] The first product and 3 g of sodium methoxide were mixed and reacted at 125° C. for 1 hour to obtain a second product;

[0064] The second product was separated and purified using a reverse osmosis membrane with a molecular weight cut-off of 300 Da at 350 psi and 42° C. to obtain β-sitosterol fatty acid ester.

[0065] Comparative Example 1

[0066] The first catalyst included 0.06 g free lipase and 0.04 g alumina (not supported on chitosan), and the rest was as in Example 1.

[0067] Comparative Example 2

[0068] The first catalyst includes 0.46 g of lipase supported on chitosan (0.4 g of chitosan, 0.06 g of lipase), excluding 0.04 g of aluminum oxide. Other contents refer to Example 1.

[0069] Comparative Example 3

[0070] After the first catalyst is used to directly catalyze the reaction for 3 hours, step S3 is entered without step S2. Other steps refer to Example 1.

[0071] Performance testing:

[0072] The multi-catalytic preparation of phytosterol derivatives obtained in the examples and comparative examples was tested, and the test contents included:

[0073] 1. Productivity: in accordance with ISO 20457:2017 standard;

[0074] 2. Purity: High performance liquid chromatography (HPLC) was used, and the chromatographic column was a C18 reverse phase column (4.6 mm*250 mm, 5 μm);

[0075] 3. Catalyst recovery rate: in accordance with ASTM E2867-14 standard;

[0076] 4. Impurity content: Gas chromatography-mass spectrometry (GC-MS) was used with a DB-5MS capillary column (30m*0.25mm*0.25μm). Impurity quantification was calculated by the area ratio of non-main peaks in the total ion current (TIC).

[0077] 5. Unreacted sterol residue: Same as “Purity” test conditions;

[0078] 6. Catalytic reactions are time-consuming.

[0079] The results are recorded in Table 1:

[0080] Table 1: Test results of Examples 1 to 6 and Comparative Examples 1 to 3

[0081]

[0082]

[0083] The yield and purity of β-sitosterol (Example 1) and avenasterol (Example 3) were relatively good. The residual amount of unreacted sterol in Examples 1-3 was less than 1.5%, indicating that the combination of the two catalytic steps can effectively promote the reaction to completion.

[0084] In Examples 4-6, the catalysis of rapeseed sterol in Example 4 and the extension of the S1 reaction time resulted in an increase in total reaction time, but a slight decrease in yield, possibly due to an increase in side reactions. The silica gel support did not perform as well as the chitosan support, but the silica gel catalyst recovery rate was slightly higher.

[0085] In Comparative Example 1, in which no lipase was loaded, the yield (68%) and purity (89%) decreased significantly, and the catalyst recovery rate was less than 10%, which verified the key role of the loaded catalyst in stability and reusability.

[0086] In Comparative Example 2, no alumina was involved in the first catalytic step, and the yield dropped to 75%, with 8% of unreacted sterol remaining, indicating that alumina as a co-catalyst can accelerate the transesterification reaction.

[0087] Comparative Example 3 omitted step S2 and directly separated, resulting in a yield of only 72% and an impurity content of 15%, proving that the sodium methoxide catalysis step of S2 is indispensable for purification and by-product conversion.

[0088] In addition, the auxiliary coordination of process parameter optimization achieves a balance between yield and energy consumption. It can be seen that the multi-catalytic method for preparing plant sterol derivatives provided by this scheme uses two different catalysts and takes advantage of the high stereoselectivity of lipase to accurately catalyze the transesterification reaction between fatty acid methyl esters and plant sterols. Alumina further improves the reaction rate and conversion rate. The high selectivity of lipase and alumina work together to avoid the occurrence of side reactions. Then, sodium methoxide is used as the second catalyst to form a two-stage catalysis, covering different reaction mechanisms, improving the purity and yield of the product, and also has the advantages of solvent reduction and less waste.

[0089] It should be noted that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the technical solution of the present invention are all included in the technical scope of the present invention. In addition, without departing from the scope of the present invention, other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present invention.

Claims

1. A method for preparing phytosterol derivatives by multi-component catalysis, characterized in that: The following steps are involved: S1, mixing fatty acid methyl ester, phytosterol and a first catalyst, heating and reducing pressure to react, to obtain a first product; S2, mixing the first product and the second catalyst and heating the mixture to react to obtain a second product; S3, separating and purifying the second product through a reverse osmosis membrane to obtain a phytosterol derivative; The first catalyst is lipase and alumina loaded on an immobilized carrier, the immobilized carrier comprises chitosan, sodium alginate or silica gel, and the second catalyst is sodium methoxide.

2. The method for preparing phytosterol derivatives by multi-catalysis according to claim 1, characterized in that: The plant sterol includes one of brassicasterol, stigmasterol, β-sitosterol and avenasterol.

3. The method for preparing phytosterol derivatives by multi-catalysis according to claim 1, characterized in that: The phytosterol derivatives include at least one of sterol esters, sterol glycosides, and acyl sterol glycosides.

4. The method for preparing phytosterol derivatives by multi-catalysis according to claim 1, characterized in that: The mass ratio of the first catalyst, the second catalyst and the phytosterol is 0.5:(2-3):(80-110).

5. The method for preparing phytosterol derivatives by multi-catalysis according to claim 1, characterized in that: The mass ratio of the immobilized carrier, the lipase and the aluminum oxide is 1:(0.1-0.2):(0.05-0.15).

6. The method for preparing phytosterol derivatives by multi-catalysis according to claim 1, characterized in that: The mass ratio of the fatty acid methyl ester to the phytosterol is (1-1.5):

1.

7. The method for preparing phytosterol derivatives by multi-catalysis according to claim 1, characterized in that: In step S1, the temperature of the temperature-raising and pressure-reducing reaction is 100° C. to 120° C., the pressure of the temperature-raising and pressure-reducing reaction is -0.055 MPa to -0.075 MPa, and the reaction time of the temperature-raising and pressure-reducing reaction is 1 to 2 hours.

8. The method for preparing phytosterol derivatives by multi-catalysis according to claim 1, characterized in that: In step S2, the temperature of the temperature-raising reaction is 120° C. to 130° C., and the reaction time of the temperature-raising reaction is 30 min to 60 min.

9. The method for preparing phytosterol derivatives by multi-catalysis according to claim 1, characterized in that: In step S3, when the reverse osmosis membrane is used to separate and purify sterol esters, its molecular weight cut-off is 200Da to 300Da.

10. The method for preparing phytosterol derivatives by multi-component catalysis according to claim 9, characterized in that: The reverse osmosis membrane separation and purification has an operating pressure of 300psi to 400psi and an operating temperature of 40°C to 45°C.

Images