Method for effectively improving extraction rate of monoterpenoids capable of soothing nerves and promoting sleep in pericarpium citri reticulatae extract

Abstract

The invention discloses a method for effectively improving the extraction rate of monoterpenoids capable of soothing nerves and promoting sleep in a pericarpium citri reticulatae extract. According to the method, the extraction solvent with oleophylic / hydrophilic conversion capability is adopted, and a specific extraction method is combined, so that the monoterpenoids with the effects of soothing the nerves and promoting sleep in the pericarpium citri reticulatae can be effectively separated and extracted, and the extraction rate and the content of the monoterpenoids are improved. According to the method, various monoterpenoids can be simultaneously dissolved by adopting a specific solvent, the monoterpenoids have higher selectivity, more volatile oil can be obtained compared with a traditional water vapor extraction method and a common hydrophilic deep eutectic solvent extraction method, and the method is suitable for efficiently extracting the monoterpenoids with the nerve calming and sleep promoting functions from the pericarpium citri reticulatae. Meanwhile, hydrophobic / hydrophilic conversion can be achieved by combining the solvent with a specific extraction method, separation of a target object and recovery of the eutectic solvent are facilitated, higher economic benefits are achieved, and more methods and ways are provided for extracting more pericarpium citri reticulatae extracts rich in monoterpenoids with the nerve calming and sleep promoting effects.

Description

Technical Field

[0001] The present invention belongs to the technical field of extracting and preparing active substances of natural products, and more specifically, relates to a method for effectively improving the extraction rate of monoterpenoid compounds in tangerine peel extracts that can calm nerves and promote sleep. Background Art

[0002] Tangerine peel (Citrus reticulata Blanco) is a dried mature peel of Rutaceae plants and is a common Chinese medicinal material. The main ingredients contained in tangerine peel are various active compounds, such as hesperidin, nobiletin, naringin, methoxyflavonoids and volatile oils. Modern pharmacological studies have shown that the active substances in tangerine peel have the traditional effects of regulating qi and strengthening the spleen, drying dampness and resolving phlegm, and have multiple pharmacological effects such as anti-oxidation, anti-inflammatory, antiviral, antibacterial, cardiovascular protection, digestion promotion, blood lipid reduction, sedation and tranquilization. Tangerine peel volatile oil has a tranquilizing and sedative effect, can help relieve tension and anxiety, and promote physical and mental relaxation. The monoterpenoid compounds it contains have a tranquilizing and sleeping effect. At present, there is a lack of a method for efficiently extracting a tangerine peel extract containing monoterpenoid compounds with a tranquilizing and tranquilizing effect, which limits the wide application of tangerine peel extracts in health care and medicinal products.

[0003] Traditional plant volatile oil extraction methods often use steam distillation. Although the steps are simple, there are great disadvantages, that is, the extraction efficiency is low, and there are still many volatile oils or active ingredients that are difficult to extract from plants in this way. For example, the prior art optimizes the extraction process of water distillation extraction by orthogonal experiment, and the extraction rate of tangerine peel essential oil is 1.98%. The method of extracting tangerine peel essential oil with enzymolysis is up to 2.37%. However, the methods of organic solvent extraction, column chromatography separation, macroporous adsorption resin, membrane separation, precipitation method, etc. have the disadvantages of high energy consumption and solvent residue. For example, existing studies use ethanol or other organic solvents as extractants, and monoterpenoid compounds in tangerine peel can be extracted by leaching and distillation. However, this method has the problems of large amount of organic solvent, easy volatility and residue, and harmful to the environment. In addition, due to its volatility and oxidizability, monoterpenoid compounds are easily affected by oxygen and high temperature in the air during the extraction process, resulting in partial degradation or volatilization, further reducing its extraction efficiency and the purity of the extract, and limiting its effect in practical applications.

[0004] Existing research has shown that tangerine peel essential oil can be efficiently extracted by low eutectic solvents, but the low eutectic solvents used are conventional and very hydrophilic components such as urea and choline chloride, which are not fully adapted to the extremely hydrophobic substance of essential oils, making it difficult to fully extract the active substances in tangerine peel volatile oils, and the extraction rate of monoterpenoids is low. The extraction rate of tangerine peel reaches 1.85%, of which the content of monoterpenoids reaches 15.85%, which still needs to be improved. In addition, there is also the problem that the extract is difficult to separate from the low eutectic solvent, which affects the effect of the extract. At present, there are few methods that can efficiently extract volatile monoterpenoids in tangerine peel extracts. Based on this, in order to improve the extraction rate of substances with sedative effects in tangerine peel, it is necessary to develop more and efficient methods for extracting monoterpenoids in tangerine peel. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the problem of low extraction rate of monoterpenoid compounds with tranquilizing and hypnotic effects in existing tangerine peel extracts, and to provide a method for effectively improving the extraction rate of monoterpenoid compounds with tranquilizing and hypnotic effects in tangerine peel extracts.

[0006] The first object of the present invention is to provide a method for improving the extraction rate of monoterpenoid compounds with tranquilizing and soothing effects in tangerine peel extract.

[0007] The second object of the present invention is to provide a kind of tangerine peel extract

[0008] The third object of the present invention is to provide application of the above method.

[0009] The fourth object of the present invention is to provide a product for calming the nerves and promoting sleep.

[0010] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0011] The invention provides a method for improving the extraction rate of monoterpenoid compounds with tranquilizing and soothing effects in a tangerine peel extract. The method comprises the following steps: extracting the tangerine peel by using a low eutectic solvent under ultrasonic conditions; introducing carbon dioxide into the tangerine peel extract obtained by extraction, then taking an oil phase for steam distillation, and collecting the extract to obtain the tangerine peel extract; the mass ratio of the tangerine peel to the low eutectic solvent is 1:(10-30); the low eutectic solvent is prepared from a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is cholesterol lauroyl glutamate, and the hydrogen bond donor is selected from one of N,N-dimethylpropylamine, methyl pyrrolidone and betaine.

[0012] The present invention improves the extraction rate and content of monoterpenoids in tangerine peel extract by screening of low eutectic reagents and optimizing extraction method conditions. The low eutectic solvent used has the ability of lipophilic / hydrophilic conversion, and can effectively separate tangerine peel extract. This ability to return to a hydrophobic state makes it a switchable solvent, which is helpful for purifying the target component and recycling the low eutectic solvent. The extraction method provided by the present invention has a simple extraction step, can improve the extraction rate of monoterpenoids in tangerine peel extract, reaching 2.93%, and significantly provides a content of terpenoids of 25.8%, which is better than the traditional steam distillation method, can obtain more volatile oils, and is suitable for efficiently extracting monoterpenoids with tranquilizing and sleeping functions in tangerine peel, and provides more effective methods and approaches for preparing more products with tranquilizing and sleeping effects.

[0013] Preferably, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:(1-3).

[0014] Preferably, the hydrogen bond acceptor is cholesteryl lauroyl glutamate, and the hydrogen bond donor is N,N-dimethylpropylamine.

[0015] The present invention utilizes a novel low eutectic solvent combined with an ultrasonic extraction method to separate and extract active ingredients with a calming and soothing function from dried tangerine peel, thereby obtaining monoterpenoid compounds with a relatively high extraction rate and content, and the prepared dried tangerine peel extract is rich in active substances such as linalool (3.4%), nerol (1.82%), terpinene (13.74%), citral (2.82%), geranyl aldehyde (1.82%), limonene (57.34%), and pinene (5.69%). The present invention uses a low eutectic solvent with lipophilic / hydrophilic conversion capability, and cholesterol lauroyl glutamate is used as a hydrogen bond donor and N,N-dimethylpropylamine is used as a hydrogen bond acceptor, and the mixture is prepared in a certain proportion. The solvent has the characteristics of strong dissolving ability, can dissolve a variety of monoterpenoid compounds at the same time, and has higher selectivity for monoterpenoid compounds; combined with a specific extraction method, carbon dioxide is introduced into the tangerine peel extract to convert the low eutectic solvent into a hydrophilic state, and the tertiary amine group of N, N-dimethylpropylamine reacts with CO2, showing strong hydrophilicity, weakening the system's affinity for monoterpenoid compounds. When CO2 is removed, N, N-dimethylpropylamine returns to its original non-polar state, and its lipophilicity is enhanced. Subsequently, the oil phase is taken for steam distillation to further purify the target product to obtain a tangerine peel extract rich in monoterpenoid compounds. By adjusting the hydrophilicity and hydrophobicity before distillation, the extraction efficiency can be effectively improved and the loss of the target product can be reduced. The two-step process can better control the extraction and separation process, ensure that the target components in the extract are fully separated, and the low eutectic solvent can be recycled again.

[0016] Preferably, the mass ratio of tangerine peel to the deep eutectic solvent is 1:(15-20).

[0017] Preferably, the ultrasonic conditions are: power 300-500W, time 30-45min, extraction temperature 40-60°C.

[0018] Preferably, the conditions for introducing carbon dioxide are: time 30-50 min, flow rate 0.15-0.35 L / min.

[0019] Preferably, the conditions for the steam distillation are: temperature 95-105° C., time 2-4 h, and pressure either normal pressure or reduced pressure.

[0020] Preferably, the tangerine peel is tangerine peel powder, which is obtained by washing, drying, and then crushing the tangerine peel through a 20-60 mesh sieve.

[0021] The invention provides a tangerine peel extract rich in monoterpenoid compounds, which is prepared by the method.

[0022] The present invention also provides application of the method in improving the extraction rate of the monoterpenoid compounds capable of tranquilizing the nerves and promoting sleep in tangerine peel extract, or in preparing tangerine peel extract or tangerine peel products capable of tranquilizing the nerves and promoting sleep.

[0023] In addition, the present invention also provides a product for calming nerves and promoting sleep, which contains the tangerine peel extract obtained by the above method.

[0024] The present invention has the following beneficial effects:

[0025] The method provided by the present invention greatly improves the extraction efficiency and content of monoterpenoid compounds in tangerine peel, and the extraction rate reaches 2.93%, wherein the content of monoterpenoid compounds reaches 25.8%, and the effect is significantly higher than the traditional steam distillation method and the ordinary hydrophilic deep eutectic solvent extraction method, and the tangerine peel extract rich in monoterpenoid compounds can be quickly extracted and prepared. And by the selection of a specific low eutectic reagent and the optimization of the extraction method conditions, by changing the lipophilic / hydrophilic properties of the extraction system, the extraction efficiency can be effectively improved, the loss of the target object can be reduced, and a best extraction method for extracting tangerine peel is obtained, which can increase the active ingredients of volatile oil in tangerine peel extract and improve its antioxidant capacity. At the same time, the present invention can realize the recovery of the deep eutectic solvent, and the method has the characteristics of easy synthesis, low price, environmental friendliness, strong solubility, high stability and safety, and provides more effective methods and approaches for extracting tangerine peel extracts rich in substances with tranquilizing and sleeping functions, and provides a certain reference basis for the development of tranquilizing and sleeping products containing tangerine peel. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The extraction efficiency of monoterpenoids by different deep eutectic solvents.

[0027] Figure 2 The efficiency of extracting monoterpenes by eutectic extraction method and traditional steam distillation method.

[0028] Figure 3 The content and extraction rate of monoterpenoid compounds in tangerine peel extracts using different extraction methods.

[0029] Figure 4 The scavenging effect of tangerine peel extract on free radicals. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0031] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0032] All raw materials used in this invention are listed in the "Catalogue of Used Cosmetic Raw Materials (2021)".

[0033] Example 1 Preparation of Tangerine Peel Extract

[0034] 1. Preparation of natural eutectic reagents (NADESs)

[0035] The hydrogen bond acceptors, hydrogen bond donors, and molar ratios are prepared according to the following Table 1. The hydrogen bond acceptors and hydrogen bond donors are mixed in proportion, and then heated at 60° C. with constant stirring until the liquid is uniformly dissolved. Then, 10% (v / v) water is added to the NADESs and mixed evenly for later use.

[0036] Table 1 Different eutectic solvent formulations

[0037]

[0038]

[0039] 2. Extraction

[0040] (1) 40 mesh dried tangerine peel powder and the low eutectic solvent prepared in Table 1 were mixed at a mass ratio of 1:20, and ultrasonic extraction was performed at a power of 400 W, an extraction temperature of 50° C., and a time of 40 min to obtain a crude dried tangerine peel extract 1;

[0041] (2) introducing carbon dioxide into the tangerine peel crude extract 1 for 40 min at a flow rate of 0.25 L / min, and after separation, collecting the oil phase to obtain the tangerine peel crude extract 2;

[0042] (3) The tangerine peel crude extract 2 is subjected to steam distillation at a temperature of 100° C., a time of 3 h, and a pressure of 0.9 bar to obtain an extract which is the tangerine peel volatile oil extract.

[0043] 3. Determination of extraction efficiency

[0044] Adopt gas chromatography-mass spectrometry (GC-MS), respectively measure the tangerine peel volatile oil extract prepared above, detect the content of its monoterpenoid compound, specific conditions are: tangerine peel volatile oil extract is evaporated under the conditions of 50 ℃, air pressure 400mbar, rotation speed 125rpm to remove excess solvent, use HP-5 column to separate components. Inlet temperature is 280 ℃, and detector temperature is 270 ℃.

[0045] Chromatographic conditions: chromatographic column: TG-5MS chromatographic column (30m×0.25mm, 0.25μm), heating program: 50℃ for 1min, increase from 10℃ to 250℃ for 9min, carrier gas flow rate: 1.0mL / min, injection volume 1μL; non-split injection.

[0046] Mass spectrometry conditions: electron bombardment ion source; electron energy 70 eV; transfer line temperature 250 °C; ion source temperature 300 °C; mass scan range 50-500 m / z, solvent delay 4 min.

[0047] Extraction efficiency of monoterpenoids: Y = m1 / m2×100%

[0048] Wherein, m1 is the mass of monoterpenoids obtained by extraction; m2 is the mass of raw materials;

[0049] The results are shown in Table 2 and Figure 1 As shown, when other conditions are the same, the extraction efficiency of monoterpenoid compounds in the tangerine peel extract is higher when the hydrogen bond donor and hydrogen bond acceptor are cholesterol lauroyl glutamate and N,N-dimethylpropylamine at a molar ratio of 1:(1-3).

[0050] Table 2 Extraction efficiency of monoterpenoids by different deep eutectic solvents

[0051]

[0052]

[0053] Among them, the hydrogen bond acceptor and donor selected in this embodiment have lower hydrophilicity than conventional low eutectic solvents, increase affinity with volatile oils, so as to extract more types of monoterpenoids and improve efficiency; the prepared low eutectic solvent has the ability of lipophilic / hydrophilic conversion and strong dissolving ability, and the hydrogen bond acceptor selects a compound containing tertiary amine, which can accept hydrogen bonds and react with CO2, showing strong hydrophilicity, converting polarity, and effectively separating the extract; combined with a specific extraction method, carbon dioxide is introduced after extraction to convert the low eutectic solvent into a hydrophilic state, reducing The system has a weak affinity for monoterpenoids. With the introduction of carbon dioxide, the low eutectic solvent will combine with water to form a two-phase separation state (water phase + oil phase); when CO2 is removed, N,N-dimethylpropylamine returns to its original non-polar state, and its lipophilicity is enhanced. In this state, monoterpenoids will be released from the low eutectic solvent to form an oil phase rich in volatile oils, which is conducive to the extraction of volatile oil monoterpenoids. Finally, the oil phase is taken for steam distillation to further purify the target, and monoterpenoids can be separated. The remaining low eutectic solvent after the extract is removed can be recycled again, including the water phase after the two-phase separation can also remove carbon dioxide by reduced pressure distillation to restore the low eutectic solvent to a lipophilic state for recycling.

[0054] By adjusting the hydrophilicity and hydrophobicity before distillation, the extraction efficiency can be effectively improved and the loss of the target object can be reduced. The low eutectic solvent prepared by the present invention is combined with a specific extraction method, so that the low eutectic solvent has the ability to return to a hydrophobic state, and switching the extraction conditions is helpful for purifying the target component and recovering the low eutectic solvent.

[0055] Example 2

[0056] The steps of the method for extracting tangerine peel based on a low eutectic solvent are the same as those of Example 1, and the natural low eutectic reagent is cholesterol lauroyl glutamate and N,N-dimethylpropylamine, which are prepared at a molar ratio of 1:2; the difference is that the temperature of the steam distillation of the tangerine peel crude extract 2 is changed to 95° C., the time is 3 h, and the pressure is 1 bar to obtain the tangerine peel extract.

[0057] Example 3

[0058] The steps of the method for extracting tangerine peel based on a low eutectic solvent are the same as those in Example 1, and the natural low eutectic reagent is prepared by standing with a molar ratio of 1:2 using cholesterol lauroyl glutamate and N,N-dimethylpropylamine; the difference is that the mass ratio of tangerine peel powder to the low eutectic solvent is adjusted to 1:15.

[0059] Example 4

[0060] The steps of the method for extracting tangerine peel based on a low eutectic solvent are the same as those of Example 1, and the natural low eutectic reagent is cholesterol lauroyl glutamate and N,N-dimethylpropylamine, which are prepared at a molar ratio of 1:2; the difference is that carbon dioxide is not introduced when the tangerine peel crude extract 1 is treated (no hydrophilic-hydrophobic conversion is performed).

[0061] Example 5

[0062] The steps of the method for extracting tangerine peel based on a low eutectic solvent are the same as those of Example 1, and the natural low eutectic reagent is cholesterol lauroyl glutamate and N,N-dimethylpropylamine, which are statically prepared at a molar ratio of 1:2; the difference is that the power of ultrasonic extraction is adjusted to 380W.

[0063] Example 6

[0064] The steps of the method for extracting tangerine peel based on a low eutectic solvent are the same as those in Example 1, and the natural low eutectic reagent is cholesterol lauroyl glutamate and N,N-dimethylpropylamine, which are statically prepared at a molar ratio of 1:2; the difference is that the power of ultrasonic extraction is adjusted to 450W.

[0065] Example 7

[0066] The steps of the method for extracting tangerine peel based on a low eutectic solvent are the same as those of Example 1, and the natural low eutectic reagent is cholesterol lauroyl glutamate and N,N-dimethylpropylamine, which are prepared at a molar ratio of 1:2. The difference is that the time of ultrasonic extraction is adjusted to 45 minutes.

[0067] Example 8

[0068] The steps of the method for extracting tangerine peel based on a low eutectic solvent are the same as those in Example 1, and the natural low eutectic reagent is cholesterol lauroyl glutamate and N,N-dimethylpropylamine, which are prepared at a molar ratio of 1:2. The difference is that the time of ultrasonic extraction is adjusted to 35 minutes.

[0069] Comparative Example 1 Traditional Steam Distillation

[0070] Select high-quality dried tangerine peel without mildew or rot, wash with clean water to remove mud and foreign matter on the surface of the fruit; put the cleaned dried tangerine peel into 75℃ hot water for 2 minutes, quickly take it out and cool it in 25℃ water, chop it, dry it and grind the sample, and pass it through a 40-mesh sieve to obtain it. Steam distill the dried tangerine peel powder at a temperature of 100℃, a time of 3 hours, and a pressure of 1 bar to obtain the dried tangerine peel extract.

[0071] Comparative Example 2: Extraction with ordinary hydrophilic eutectic solvent

[0072] The extraction preparation method is the same as that of Example 1, except that the hydrogen bond donor of the natural low eutectic reagent is urea, and the hydrogen bond acceptor is choline chloride, with a molar ratio of 1:2.

[0073] Comparative Example 3

[0074] The steps of the method for extracting tangerine peel based on a low eutectic solvent are the same as those of Example 1, and the natural low eutectic reagent is cholesterol lauroyl glutamate and N,N-dimethylpropylamine, which are prepared at a molar ratio of 1:2; the difference is that steam distillation is not performed.

[0075] Comparative Example 4

[0076] The steps of the method for extracting tangerine peel based on a low eutectic solvent are the same as those of Example 1, and the natural low eutectic reagent is cholesterol lauroyl glutamate and N,N-dimethylpropylamine, which are prepared at a molar ratio of 1:2; the difference is that the steam distillation temperature of the tangerine peel crude extract 2 is changed to 85°C.

[0077] Test Example 1 Effect of different extraction conditions on the content of effective substances in dried tangerine peel

[0078] 1. Different extraction methods

[0079] The tangerine peel was extracted by the low eutectic solvent extraction method (DESs-1) in Example 1 and the traditional steam distillation method in Comparative Example 1, and the extraction and preparation were carried out at 40° C. and 60° C. under ultrasonic conditions (power 400 W, time 40 min), respectively, and the other method conditions were the same. Then, the monoterpene compound content of different extracts was determined by the determination method in Example 1.

[0080] The extraction results of dried tangerine peel by different methods are as follows Figure 2 As shown, the content of monoterpenoids extracted by low eutectic reagent is significantly higher than that of tangerine peel extract by water extraction. Further comparison of the effects of low eutectic reagent and traditional steam distillation on the content of monoterpenoids in the extract at different extraction temperatures found that there were significant differences in the extraction of monoterpenoids by low eutectic reagent at different extraction temperatures, showing that the content of monoterpenoids extracted at extraction temperatures of 40°C and 60°C was significantly different. Low temperature will lead to incomplete extraction, and high temperature will cause some essential oils to volatilize and cause loss. At 50°C, a higher content of volatile oil can be extracted.

[0081] Moreover, it has been determined that the method provided by the present invention can obtain more volatile oils than the traditional steam extraction method, and obtain a tangerine peel extract containing active substances such as linalool (3.4%), nerol (1.82%), terpinene (13.74%), citral (2.82%), geranial (1.82%), limonene (57.34%), and pinene (5.69%).

[0082] 2. Extraction conditions

[0083] In Examples 1 (DESs-1) and 3, by adjusting the mass ratio of tangerine peel to the low eutectic solvent, the measurement showed that the monoterpene content and extraction rate of the tangerine peel extract obtained by Example 1 (DESs-1) were optimal, reaching 25.87% and 2.93%.

[0084] The results of the determination of the monoterpenoid content of the tangerine peel extracts prepared in Comparative Examples 1 (DESs-1) and 5 to 8 are shown in Tables 3 and Figure 3 As shown, different extraction conditions will affect the content of monoterpenoid compounds. The tangerine peel extract prepared under the conditions of Example 1 (DESs-1) has the highest content of monoterpenoid compounds. Compared with the traditional low eutectic solvent used in Comparative Example 2, the low eutectic solvent used in the present invention has higher selectivity for monoterpenoid compounds and can dissolve multiple monoterpenoid substances at the same time. In Examples 5 to 8, the extraction effect did not change much by adjusting the ultrasonic conditions, which was close to the effect of Example 8. In principle, the influence of steam distillation temperature is usually greater than that of ultrasonic conditions, because the distillation temperature directly determines the volatilization and extraction efficiency of monoterpenoid compounds, while ultrasound affects the extraction rate more. Therefore, compared with the existing extraction methods, the method provided by the present invention can significantly improve the content and extraction rate of monoterpenoid compounds in tangerine peel extracts.

[0085] Table 3 Content and extraction rate of monoterpenoid compounds in tangerine peel extracts by different extraction methods

[0086]

[0087] Test Example 2: Deep eutectic solvent recycling experiment

[0088] The low eutectic solvent prepared in Example 1 (DESs-1) was added to the absorption bottle, and the carbon dioxide absorption experiment was carried out by bubbling the liquid with gas, specifically, carbon dioxide gas with a moisture content of 0.5% was introduced at room temperature and normal pressure, the flow rate of carbon dioxide was 100mL / min, and it was weighed every 1min until the weight of the absorption bottle remained unchanged, and the absorption of carbon dioxide was calculated by mass weighing difference subtraction. After the absorption was completed, the water content of the saturated hydrophobic low eutectic solvent after absorbing carbon dioxide was determined by Karl Fischer moisture meter. The remaining saturated liquid was thermally desorbed under normal pressure, 80°C, and nitrogen purge conditions, with a nitrogen flow rate of 100mL / min, to complete a cycle of absorption-desorption experiment. After the desorption was completed, the water content of the hydrophobic low eutectic solvent after desorption of carbon dioxide was determined by Karl Fischer moisture meter.

[0089] The results are shown in Table 4. Three cycles of absorption-desorption experiments were performed continuously. The average absorption amount of carbon dioxide by the hydrophobic low eutectic solvent during the three cycles of absorption-desorption was calculated to be 0.71 g CO2 / g DES, and the cyclic absorption capacity did not decrease significantly. During the cyclic absorption-desorption process, the moisture content of the hydrophobic low eutectic solvent was always less than 2%, which can be explained that the low eutectic solvent used in the present invention absorbs almost no moisture during the cyclic absorption-desorption of carbon dioxide, ensuring the absorption capacity of the hydrophobic low eutectic solvent, so that the hydrophobic low eutectic solvent used in the present invention has good cyclic performance, can be used for the cyclic absorption-desorption of water-containing carbon dioxide for many times, promotes the recovery of the low eutectic solvent, and has higher economic benefits.

[0090] Table 4 DES cycle absorption-desorption of carbon dioxide

[0091]

[0092] Test Example 3 Determination of DPPH free radical scavenging ability

[0093] Since oxidative stress can cause mood disorders and sleep disorders, leading to insomnia, the DPPH free radical scavenging ability of the prepared tangerine peel extract was determined. Accurately weigh 4 mg DPPH and dissolve it in methanol to a 100 mL volumetric flask to obtain the DPPH solution. Take 0.1, 0.3, and 0.5 mL of different tangerine peel extracts (fill up the insufficient volume to 0.5 mL with methanol) and 2 mL of DPPH solution in the same test tube and shake well. Place in the dark for 30 minutes, use the corresponding blank solution as a control, and measure its absorbance at 517 nm. The DPPH free radical inhibition rate is calculated as follows:

[0094] Inhibition rate % = [A0-(A b -A * )] / A0*100%

[0095] Where: A0 is the absorbance after reaction without adding sample inhibitor;

[0096] A b is the absorbance after adding sample inhibitor;

[0097] A * is the absorbance without adding inhibitor and DPPH.

[0098] The results of free radical scavenging rate determination are shown in Table 5. The results of adjusting the concentration of monoterpenoid compounds in different samples show that as the concentration of monoterpenoid compounds increases, the antioxidant effect becomes better, among which the effect of Example 1 (DESs-1) group is the best. Figure 4 shown.

[0099] Table 5 Scavenging effect of tangerine peel extract on free radicals

[0100]

[0101]

[0102] Test Example 4 Effect of Tangerine Peel Extract on Sleep Latency of Threshold-Dose Sodium Pentobarbital Sleep Mice

[0103] Experimental procedure: Kunming mice (SPF grade, Guangdong Medical Experimental Animal Center) were divided into 9 groups. After the mice were raised normally for one week, the experiment began on the 8th day. The mice were weighed and recorded before the experiment. The mice in the control group were gavaged with distilled water every day, and the mice in the tangerine peel extract group were gavaged with tangerine peel extract every day. Subsequently, the mice in the tangerine peel extract group were exposed to the whole body for 5 minutes, and then sniffed the tangerine peel extract (2 mg mL -1 ), sniffing for 30 min every day for 7 days. After the last day of administration, each group of mice was intraperitoneally injected with 45 mg kg -1 Sodium pentobarbital solution was injected. After the injection, the mice were placed individually in a feeding box, and the feeding boxes were numbered. The time when the righting reflex of each mouse disappeared for 1 min was recorded. After the righting reflex of the mouse was recovered, the time was recorded.

[0104] The experimental results are shown in Table 6. Compared with the control group, the tangerine peel extract prepared in the embodiments of the present invention can significantly shorten the sleep latency of mice and prolong the sleep time. Among them, Example 1 (DESs-1) has the best effect and can significantly improve the sleep quality of mice to achieve a better calming and sleeping effect.

[0105] Table 6 Sleep quality assessment results

[0106]

[0107] In summary, the present invention adopts an extraction solvent with lipophilic / hydrophilic conversion ability, and combines a specific extraction method to convert the polarity of the extraction system, effectively separate and extract monoterpenoid compounds, and can effectively improve the extraction rate and content of monoterpenoid compounds in tangerine peel extract for tranquilizing the nerves and sleeping; and, after the extract is separated from the solvent, the extraction solvent can be recycled again, including the water phase after the two-phase separation can also be removed by vacuum distillation to remove carbon dioxide, so that the low eutectic solvent is restored to a lipophilic state for recycling, which is helpful for the separation of the target and the recovery of the low eutectic solvent, and has higher economic benefits. The content and purity of monoterpenoid compounds in the tangerine peel extract prepared by the method provided by the present invention are higher than those of the traditional steam distillation method and the traditional low eutectic solvent, and a tangerine peel extract rich in monoterpenoid compounds can be prepared, and its active substance content is increased, thereby increasing the ability of the tangerine peel extract to tranquilize the nerves and sleep, and providing a certain reference basis for the development of tangerine peel tranquilizing products.

[0108] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for increasing the extraction rate of monoterpenoid compounds in tangerine peel extract that can calm nerves and promote sleep, characterized in that: The method comprises the following steps: extracting tangerine peel by using a low eutectic solvent under ultrasonic conditions; introducing carbon dioxide into the tangerine peel extract obtained by the extraction, then taking the oil phase for steam distillation, and collecting the extract; The mass ratio of the tangerine peel to the deep eutectic solvent is 1:(10-30); The low eutectic solvent is prepared from a hydrogen bond acceptor and a hydrogen bond donor, wherein the hydrogen bond acceptor is cholesterol lauroyl glutamate, and the hydrogen bond donor is selected from one of N,N-dimethylpropylamine, methyl pyrrolidone and betaine.

2. The method according to claim 1, characterized in that: The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:(1-3).

3. The method according to claim 2, characterized in that: The hydrogen bond donor is N,N-dimethylpropylamine.

4. The method according to claim 3, characterized in that: The mass ratio of the tangerine peel to the deep eutectic solvent is 1:(15-20).

5. The method according to claim 1, characterized in that: The ultrasonic conditions are: power 300-500W, time 30-45min, extraction temperature 40-60°C.

6. The method according to claim 1, characterized in that: The conditions for introducing carbon dioxide are: flow rate 0.15-0.35 L / min, time 30-50 min.

7. The method according to claim 1, characterized in that: The conditions of the steam distillation are: temperature 95-105° C., time 2-4 h.

8. A tangerine peel extract, characterized in that The invention is prepared by the method according to any one of claims 1 to 7.

9. Use of the method according to any one of claims 1 to 7 in increasing the extraction rate of tranquilizing and sleeping monoterpenoid compounds in tangerine peel extract, or in preparing tranquilizing and sleeping products.

10. A product for calming nerves and promoting sleep, characterized in that: Containing the tangerine peel extract according to claim 8.

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