An oral sustained-release preparation for increasing 5-HT level in brain and its application in improving insomnia

Abstract

The application discloses an oral preparation capable of improving 5-HT level in the brain and application thereof in improving insomnia, and belongs to the field of food science. The oral preparation uses starch and beta-cyclodextrin as nanoparticle carriers to wrap 5-HTP, can effectively control the release rate of 5-HTP, makes it slowly release in the gastrointestinal tract, and improves the defect that the half-life of 5-HTP is short. The preparation can significantly improve the content of 5-HT in the brain, and improve the metabolic kinetic characteristics of 5-HT, thereby effectively improving the insomnia symptoms. Experimental data shows that, compared with the traditional 5-HTP, the slow-release preparation has better bioavailability and longer brain drug efficacy duration. The innovative preparation not only has significant advantages in technology, but also opens up a new, safe and effective way for the treatment of 5-HT related nervous system diseases, and has important application value and research significance.

Description

Technical Field

[0001] This invention relates to the preparation and functional application of an oral sustained-release formulation of 5-HTP encapsulated in nanoparticles, belonging to the field of pharmaceutical science. Background Technology

[0002] With the fast pace of modern life and increasing stress, insomnia has seriously affected people's quality of life and health. Insomnia not only leads to daytime drowsiness and poor concentration, but can also trigger a series of psychological and physiological problems, such as depression, anxiety, and cardiovascular disease. 5-HT is an important neurotransmitter widely distributed in the central and peripheral nervous systems. Studies have shown that 5-HT plays a crucial role in regulating mood, sleep, and appetite. Particularly in sleep regulation, 5-HT is closely related to melatonin synthesis and can promote the periodic transition between rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep, thereby regulating sleep structure and quality. Existing research indicates that decreased 5-HT levels in the brain are closely related to the occurrence of insomnia, but peripheral 5-HT cannot cross the blood-brain barrier to enter the brain.

[0003] Currently, medications for treating insomnia are mainly divided into two categories: one is traditional sleeping pills, such as benzodiazepines. While these can quickly induce sleep, long-term use can easily lead to drug tolerance and dependence, and may also cause residual sedation the next day. The other category is selective serotonin reuptake inhibitors (SSRIs). These drugs improve mood and sleep by blocking the reuptake of serotonin in the synaptic cleft, increasing the concentration of serotonin in the synaptic cleft. However, these drugs are effective for only one-third of patients. 5-HTP, on the other hand, can be rapidly converted into serotonin after crossing the blood-brain barrier, increasing the level of serotonin in the brain. Therefore, directly supplementing with the serotonin precursor 5-HTP is considered a safer, faster-acting, and more universally applicable alternative. However, 5-HTP is metabolized rapidly in the body; the peak plasma concentration after oral administration is usually reached within 1-2 hours, but then declines rapidly, resulting in a short duration of action, which makes its effectiveness as a treatment for insomnia less than ideal. When 5-HTP is co-administered with an amino acid decarboxylase inhibitor (DCI), the half-life can be doubled, but DCI still cannot cross the blood-brain barrier to enter the brain and still acts on the periphery.

[0004] In order to better prolong the half-life of 5-HTP and improve sleep quality, it is urgent to develop related sustained-release formulations of 5-HTP. Summary of the Invention

[0005] This invention addresses the short in vivo half-life of 5-HTP by providing a 5-HTP nano-oral sustained-release formulation prepared by combining starch and β-cyclodextrin. This formulation has advantages such as high encapsulation efficiency, slow release, stable brain 5-HT levels, and prevention and / or relief of sleep disorders.

[0006] The first technical solution provided by this invention is a method for preparing a 5-HTP oral sustained-release formulation, comprising the following steps: S1, 5-HTP and corn starch are dissolved in water to form a mixture. Ethanol solution is added dropwise to the mixture while stirring. Then, the mixture is sonicated and the ethanol is rotary evaporated to obtain a complex. S2, β-cyclodextrin is added to the complex from step S1 and stirred overnight. The mixture is then sonicated, centrifuged, and the supernatant is collected and freeze-dried to obtain a 5-HTP oral sustained-release formulation modified with starch and β-cyclodextrin nanoparticles.

[0007] In one embodiment, in step S1, the mass ratio of 5-HTP to corn starch is 10:1 to 1:500, preferably, the mass ratio of 5-HTP to corn starch is 1:2.

[0008] In one embodiment, in step S1, the concentration of 5-HTP in the mixture is 0.1~10 mg / mL, and the concentration of corn starch is 1~50 mg / mL; preferably, the concentration of 5-HTP is 5 mg / mL, and the concentration of corn starch is 10 mg / mL.

[0009] In one embodiment, in step S1, the concentration of the ethanol solution is 70-75%, and the volume ratio of the ethanol solution to the mixture is 1:2-2:1. Preferably, the volume ratio of the ethanol solution to the mixture is 1:1.

[0010] In one embodiment, in step S1, the dropping rate of the ethanol solution is 0.1~1 mL / min, and optionally, the dropping rate of the ethanol solution is 0.4 mL / min.

[0011] In one implementation, the ultrasound time in step S1 is 1 hour.

[0012] In one embodiment, in step S2, the mass ratio of β-cyclodextrin to corn starch is 1:10 to 10:1, and optionally, the mass ratio of β-cyclodextrin to corn starch is 1:1.

[0013] In one embodiment, in step S2, the parameters for overnight stirring are as follows: magnetic stirring at 700 rpm / min overnight at 50°C.

[0014] In one implementation, the ultrasound time in step S2 is 1 hour.

[0015] In one embodiment, in step S2, centrifugation at 12000g for 15min is performed.

[0016] The second technical solution provided by the present invention is an oral sustained-release formulation of 5-HTP, wherein the sustained-release formulation includes a nanocarrier, the nanocarrier being encapsulated with 5-HTP, the nanocarrier being composed of starch and β-cyclodextrin in a mass ratio of 1:10 to 10:1, the nanocarrier having an encapsulation rate of 84.58 to 94.27% for 5-HTP and a loading rate of 62.65 to 69.83%.

[0017] The third technical solution provided by the present invention is a drug containing the 5-HTP oral sustained-release formulation described in the second technical solution.

[0018] The fourth technical solution provided by the present invention is the method described in the first technical solution, or the application of the oral sustained-release agent described in the second technical solution in the preparation of drugs for the prevention, improvement and / or treatment of sleep disorders.

[0019] In one embodiment, the sleep disorder includes, but is not limited to, abnormal sleep volume and abnormal behavior during sleep.

[0020] In one implementation, the application also includes preventing and / or alleviating behavioral abnormalities caused by sleep disorders.

[0021] In one embodiment, the application also includes regulating emotional abnormalities, protecting cognitive and memory abilities, and restoring the ability of central nerve fibers to release receptors normally.

[0022] The technical effects of this invention are as follows: This invention provides a 5-HTP nanoparticle-based oral sustained-release formulation for the prevention and / or relief of sleep disorders, prepared using a combination of starch and β-cyclodextrin. By encapsulating 5-HTP in a nanocarrier composed of starch and β-cyclodextrin, high encapsulation efficiency and slow release are achieved, effectively increasing 5-HT levels in the brain, stabilizing its effect on the nervous system, and preventing and / or alleviating sleep disorders such as insomnia caused by insufficient 5-HT levels. This sustained-release formulation achieves long-term release via oral administration, reducing the frequency of dosing and improving patient compliance. Starch and β-cyclodextrin are biocompatible natural food materials, ensuring the safety and non-toxicity of the formulation. By stably increasing 5-HT levels in the body, it significantly improves mood and sleep quality, providing a safe, effective, and non-addictive treatment option for insomnia patients. This invention expands the application of 5-HTP, has significant implications for drug research and development, and opens up new avenues and solutions for the prevention and treatment of insomnia and related mood disorders. Attached Figure Description

[0023] Figure 1 The encapsulation capacity and functional groups of 5-HTP oral sustained-release formulation modified with starch and β-cyclodextrin nanoparticles change with decreasing mass ratio of starch to β-cyclodextrin. (A) Encapsulation efficiency and loading rate; (B) Fourier transform infrared spectroscopy.

[0024] Figure 2 The particle size of a 5-HTP oral sustained-release formulation modified with starch and β-cyclodextrin nanoparticles changes as the mass ratio of starch to β-cyclodextrin decreases. (A) Particle size; (B) Zeta potential.

[0025] Figure 3 Release experiments were conducted on an oral sustained-release formulation of 5-HTP modified with starch and β-cyclodextrin nanoparticles. (A) Gastric juice simulated digestion release; (B) Intestinal juice simulated digestion release; the 0 time point for intestinal juice digestion was calculated starting 2 hours after gastric juice digestion.

[0026] Figure 4 This study compares the oral pharmacokinetics of 5-HTP sustained-release formulation and 5-HTP. (A) Serum 5-HTP concentration-time curve; (B) Area under the curve / maximum concentration / duration of high concentration; where the area under the curve is at a baseline of 0 μg / L, maximum concentration refers to the highest concentration of 5-HTP in serum, and high concentration refers to concentrations above 500 μg / L. ***P<0.001; ****P<0.0001.

[0027] Figure 5 Comparison of oral intracranial metabolic kinetics of 5-HTP sustained-release formulation and 5-HTP. (A) Changes in brain 5-HT content over time; (B) Changes in brain NAS content over time. NAS is a downstream metabolite of 5-HT.

[0028] Figure 6 The results represent the performance of mice in behavioral experiments. (A) Sleep duration; (B) Time spent exploring the central open field; (C) Discrimination score for recognizing new objects. P < 0.0001. Detailed Implementation

[0029] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0030] Test method: 1. Encapsulation and Loading Rate Detection: The free 5-HTP content in the supernatant of the starch and β-cyclodextrin nanoparticle-modified 5-HTP oral sustained-release formulation was determined by HPLC. 1 mL of nanoparticle suspension was centrifuged, and the precipitate was washed three times with an equal volume of ultrapure water. All supernatants were collected and centrifuged at 12000 g for 15 min. The supernatant was filtered through a 0.22 μm filter membrane and added to an inner-lined tube, then placed in a HPLC vial for analysis. Standards were diluted using the supernatant from empty nanoparticles. The encapsulation and loading rates were calculated as follows: Encapsulation rate (%) = ×100.

[0031] Loading rate (%) = ×100.

[0032] In the formula: M1 represents the total amount of 5-HTP added (mg), M2 represents the amount of free (unencapsulated) 5-HTP (mg), and M3 represents the mass of the empty-load sustained-release formulation (mg).

[0033] 2. Fourier Transform Infrared Spectroscopy: After lyophilization, the nanoparticle formulation was measured at 4000 cm⁻¹ at room temperature using a Fourier transform infrared spectrometer. 1 to 650 cm FTIR spectrum of 1.

[0034] 3. Nanoparticle size detection: Before centrifugation, 1 mL of the nanoparticle solution was taken and diluted 10 times with ultrapure water. The particle size and zeta potential were detected using a Zetasizer nano ZS instrument.

[0035] 4. In vitro release rate assay: The release rate of the 5-HTP oral sustained-release formulation was determined using simulated gastrointestinal fluid. Simulated gastric fluid (SGF, pH 3.0) and simulated intestinal fluid (SIF, pH 7.4) were prepared according to the INFOGEST consensus protocol. 1 mg of lyophilized sample was weighed and added to 10 mL of simulated gastrointestinal fluid, and incubated at 37°C with shaking. The gastric and intestinal fluid environments were incubated at intervals of 15 min and 30 min, respectively. 20 μL of each sample solution was collected, centrifuged at 12000 g for 15 min, and the supernatant was filtered through a 0.22 μm organic filter membrane. The filtrate was added to a liner tube, and the 5-HTP content in the solution was determined by HPLC. Standards were diluted using the supernatant from empty formulation digestion. The in vitro release rate was calculated using the following formula: In vitro release rate (%) = ×100.

[0036] 5. Serum 5-HTP content detection: Take 100 μL of serum sample, add 800 μL of methanol, vortex for 15 s, and homogenize 3 times at 65 Hz. Centrifuge the mixed sample at 15000 g for 10 min, collect the supernatant and concentrate it under vacuum for 2 h to evaporate to dryness, add 100 μL of 10% methanol solution, shake well, centrifuge at 15000 g for 10 min, and transfer the supernatant to a liquid chromatography vial with an inner liner for analysis.

[0037] 6. Detection of 5-HT and its metabolite NAS in the brain: Weigh a certain amount of sample and place it in an EP tube containing 3mm diameter zirconium beads. Add 900μL of 50% methanol solution. Vortex for 15s, set to 65Hz, homogenize three times, and incubate at -20℃ for 1h. Centrifuge at 15000g for 10min, and collect the supernatant for vacuum concentration at 45°C for 2-4h. Add 100μL of 10% methanol solution to the precipitate, shake to resuspend, incubate at -20℃ for 2h, centrifuge at 15000g for 10min at 4°C, and transfer the supernatant to a liquid chromatography vial containing a liner for analysis.

[0038] 7. HPLC Parameter Settings: A Waters Atlantis T3 column (250 mm × 4.6 mm, 5 μm) was used for substance separation. Mobile phase A was 0.01 mol / L PBS, adjusted to pH 4.0 with phosphoric acid. Mobile phase B was chromatographic grade acetonitrile. The gradient elution method was: 5% B, 0–1 min; 95% B, 1–12 min; 95% B, 12–15 min; 5% B, 15–16 min; 5% B, 16–20 min. The flow rate was 1 mL / min, and the column temperature was set to 35℃. The injection volume was 10 μL. A fluorescence detector was used for detection, with an excitation wavelength of 280 nm and an emission wavelength of 360 nm. External standard method was used for quantification.

[0039] 8. LC-MS Parameter Settings: A DIONX UltiMate 3000 HPLC system coupled with a Q-Exactive mass spectrometer was used for detection. The separating column was an ACQUITY UPLC® BEH C18 column (1.7µm, 100mm × 2.10mm). The injection volume was 2μL, mobile phase A was 0.1% formic acid in water, and mobile phase B was acetonitrile. The column temperature was 35℃, the sample chamber temperature was 4℃, and the flow rate was 0.3mL / min. The gradient elution method was 5% B, 0~3 min; 30% B, 3~9 min; 100% B, 9~12 min; 100% B wash to 13.5 min; 5% B, 13.5~15 min. The mass spectrometry conditions were positive ion scan mode, spray voltage 3500 V, ion source temperature 320℃, and nitrogen was used as the protective gas and auxiliary gas for the mass spectrometer.

[0040] Raw materials used in the examples: 1. Corn starch (CAS: 9005-25-8) and β-cyclodextrin (CAS: 7585-39-9, molecular weight 1134.98, purity ≥98%) were both sourced from Shanghai Aladdin Reagent Co., Ltd.

[0041] 2. All other reagents were sourced from Sinopharm Group.

[0042] 3. Wistar rats were obtained from Beijing Vital River Laboratory Animal Technology Co., Ltd., 8 weeks old, weighing ~400g.

[0043] 4. C57BL / 6J mice were obtained from Beijing Vital River Laboratory Animal Technology Co., Ltd., 8 weeks old, weighing ~25g.

[0044] Example 1: Preparation of oral formulations modified with 5-HTP nanoparticles The preparation steps of the 5-HTP oral formulation modified with starch and β-cyclodextrin nanoparticles are as follows: 5-HTP and corn starch (w:w=1:2, 10 mg / mL) were dissolved in ultrapure water. A 70-75% ethanol solution (v:v=1:1) was added dropwise at 0.4 mL / min with stirring. The mixture was sonicated for 1 h, and the ethanol was rotary evaporated. β-cyclodextrin was added and the mixture was magnetically stirred overnight at 700 rpm / min at 50 °C. After sonication for 1 h, the mixture was centrifuged at 12000 g for 15 min, the supernatant was removed, and the mixture was freeze-dried to obtain an oral sustained-release formulation of 5-HTP modified with starch and β-cyclodextrin nanoparticles.

[0045] Different formulations were obtained by using seven different ratios of starch to β-cyclodextrin: 10:1, 5:1, 2:1, 1:1, 1:2, 1:5, and 1:10. Single-factor process optimization experiments were conducted to study the effects of these ratios on the encapsulation efficiency, particle size, and chemical structure of nanoparticles.

[0046] (1) Determination of 5-HTP encapsulation ability of nanoparticle-modified oral formulations The 5-HTP nanoparticle-modified oral formulation prepared in Example 1 was analyzed for encapsulation efficiency and loading rate using high-performance liquid chromatography (HPLC). The results are as follows: Figure 1 As shown in (A), the encapsulation efficiency and loading rate changed significantly with decreasing starch to β-cyclodextrin mass ratio, both reaching their highest levels at a 1:1 ratio. Furthermore, Fourier transform infrared spectroscopy (FTIR) analysis revealed the formation of chemical bonds between 5-HTP and the carrier in the formulation, such as... Figure 1 (B), 3273 cm 1 The strong absorption bands nearby are caused by the stretching of the -OH groups of starch, which promotes the bonding between and within nanoparticles. The peak width indicates the degree of intermolecular and intramolecular hydrogen bonding. Meanwhile, the stretching vibrations of β-cyclodextrin on the two-carbon conjugated system are observed at 1020 cm⁻¹. 1 A strong absorption band was observed. The results showed that the hydrogen bond absorption peak shifted to varying degrees with changes in the mass ratio of starch to β-cyclodextrin, further verifying that 5-HTP was more effectively encapsulated at a ratio of 1:1, and that the degree of hydrogen bond migration was more conducive to the formation of nano-formulations.

[0047] (2) Particle size analysis of nanoparticle-modified oral formulations The particle size of the nanoparticle-modified oral sustained-release formulation prepared in Example 1 was determined using a laser particle size analyzer, and its surface charge was determined using a Zeta potential analyzer. The results are as follows: Figure 2 As shown in (A) and (B), the particle size of nanoparticles initially decreases and then increases with decreasing starch-to-β-cyclodextrin mass ratio, reaching its minimum at a mass ratio of 1:1. The Zeta potential indicates that the nanoparticle surface is negatively charged, and its absolute value initially decreases and then remains constant with decreasing ratio. This suggests that the addition of β-cyclodextrin causes nanoparticle aggregation, with the aggregation reaching an optimal level at a 1:1 ratio. Simultaneously, the increased adsorption of 5-HTP leads to a greater negative surface charge due to its -OH groups, indicating better encapsulation of 5-HTP. When the mass ratio is greater than that of corn starch, the particle size tends to increase due to its hollow structure, but the charge does not change significantly. Different carrier ratios have a significant impact on the physicochemical properties of nanoparticles, potentially affecting drug release characteristics and bioavailability.

[0048] Example 2: Nanoparticle-modified oral formulations can achieve slow release of 5-HTP In Example 1, the 5-HTP nanoparticle-modified oral sustained-release formulation containing starch and β-cyclodextrin at a mass ratio of 1:1 underwent in vitro release experiments with 5-HTP in simulated gastrointestinal fluid. Digestion was performed in a 37°C constant-temperature shaking incubator, and samples were taken at regular time points. The release amount of 5-HTP was determined using HPLC. The results are as follows: Figure 3 (A) and Figure 3 As shown in (B), the unencapsulated 5-HTP is released immediately in the gastric environment, while the sustained-release formulation of 5-HTP is pH responsive. After 2 hours, the release rate in the gastric environment is about 20%, and the maximum release rate is about 40% after 6 hours. This indicates that the nano-modification gives it resistance to gastric digestion. After digestion by intestinal fluid, 5-HTP can be completely released at a slow rate and can be completely digested after 8 hours. This significantly improves the stability and bioavailability of 5-HTP in the simulated gastrointestinal tract, indicating that the formulation may have a good sustained-release effect in vivo.

[0049] Furthermore, in vivo pharmacokinetic experiments were conducted for comparison. Twelve rats were divided into two groups, and administered ordinary 5-HTP by gavage to one group and the sustained-release 5-HTP formulation prepared in Example 1 to the other group. Blood samples were collected from the tail vein at different time points, and serum samples were obtained by centrifugation at 4000g for 15 min. The concentration of 5-HTP in the serum was determined by LC-MS. The results are as follows: Figure 4 As shown in (A) and (B), the sustained-release formulation of 5-HTP maintained a high serum concentration for 10.0–11.7 hours, while the conventional 5-HTP group only maintained it for 1.9–2.8 hours. Furthermore, the area under the curve (AUC) of the sustained-release formulation was significantly higher than that of the conventional 5-HTP formulation by 24–2.7 times, indicating that the sustained-release formulation of 5-HTP has a better sustained-release effect, helping to maintain the long-term action of 5-HTP and improving its short half-life. In addition, the maximum concentration was significantly lower than that of the conventional 5-HTP group by 3 / 5–4 / 5 times, indicating that the sustained-release formulation of 5-HTP can avoid the acute release of 5-HTP after ingestion, effectively preventing side effects such as serotonin syndrome.

[0050] Example 3: 5-HTP sustained-release formulation can improve cerebral metabolic dynamics Thirty-six mice were divided into two groups and administered ordinary 5-HTP by gavage, while the other group was given a sustained-release 5-HTP formulation prepared in Example 1 with a starch to β-cyclodextrin mass ratio of 1:1. Brain tissue samples were collected at six different time points: 0, 1, 2, 4, 6, and 10 h. The contents of 5-HT and its metabolite NAS in the brain were determined by HPLC.

[0051] The results are as follows Figure 5As shown in (A), the 5-HT content in the brains of mice in the ordinary 5-HTP group began to increase significantly 1 hour after gavage, reaching a peak at 2 hours, and then gradually decreased, returning to normal physiological levels at 4 hours. In contrast, the 5-HT content in the 5-HTP sustained-release formulation group showed a more stable trend throughout the monitoring period, with the peak delayed until 4 hours, and remaining at a high level at 6 and 10 hours. This indicates that the sustained-release formulation can effectively prolong the presence time of 5-HT in the brain and improve its metabolic kinetics. Furthermore, the content changes of NAS, as a downstream metabolite of 5-HT, were also monitored, and the experimental results are shown below. Figure 5 As shown in (B), the trend of NAS content changes is similar to that of 5-HT. In the 5-HTP sustained-release group, NAS gradually increases after 2 hours and reaches its peak at about 5 hours. Compared with the pure 5-HTP group, the metabolic rate of NAS is slower, and the higher level can be maintained for up to 10 hours. This indicates that the sustained-release formulation can not only prolong the duration of action of 5-HT in the brain, but also have a positive impact on its metabolic process, thereby helping to improve related neurophysiological functions.

[0052] Example 4: 5-HTP sustained-release formulation can improve behavioral abnormalities in insomnia mice Twenty-eight mice were selected, and a 12-hour:12-hour diurnal cycle was ensured for them. Animal grouping and treatment methods are shown in Table 1.

[0053] Table 1. Animal experimental grouping and treatment methods

[0054] Insomnia model: After one week of environmental adaptation, mice were subjected to 20 hours of sleep deprivation daily for 15 days. The control group remained undisturbed. Behavioral tests, including sleep monitoring, open field test, and novel object recognition test, were conducted on mice starting on day 16.

[0055] Sleep monitoring: Sleep / wake analysis was performed on mice. The mice were placed in cages with identical environments, and their sleep and wakefulness durations were recorded over 24 hours, maintaining a 12-hour:12-hour day-night cycle. The experimental results are as follows: Figure 6 (A) Sleep deprivation induced mice to remain awake for 190 minutes per day, accounting for approximately 87% of the total time. In contrast, oral administration of 5-HTP sustained-release formulation enabled mice to sleep for 52% of the total time per day, effectively regulating the abnormal amount of sleep. Meanwhile, oral administration of 5-HTP only achieved 22% of the total sleep time and could not effectively improve insomnia.

[0056] Open field experiment: Before the experiment, the mice were acclimatized to the environment. The mice were placed in the center of a 40 cm × 40 cm open field for 6 minutes to explore. The exploration time in the center of the open field was recorded. The percentage of time spent in the center area was calculated as: (Central area dwell time / Total time) × 100. The experimental results are as follows: Figure 6 (B) Sleep deprivation significantly reduced the proportion of time mice spent in the central region, impaired their exploration ability, and caused them to exhibit hyperactivity and anxiety-like behaviors. Intervention with 5-HTP sustained-release formulation could alleviate these emotional abnormalities and improve sleep quality, while 5-HTP intervention had no such effect.

[0057] New object recognition experiment: Two different objects were placed at opposite ends of the side wall. The mouse was placed in the center of the box and allowed to learn for 10 minutes. After 24 hours, one object was replaced with a new object (with a significantly different shape). The mouse was then placed in the box again in the same manner and tested for 10 minutes. The time spent exploring the new object was recorded. The recognition difference score was calculated as follows: (Time spent exploring the new object - Time spent exploring the familiar object) / (Time spent exploring the new object + Time spent exploring the familiar object). A positive difference score indicates that more time was spent exploring the new object; a negative score indicates that more time was spent exploring the familiar object; and zero indicates that the same amount of time was spent exploring both objects. The experimental results are as follows: Figure 6 As shown in (C), stressed mice have impaired cognitive memory of new objects, and administration of 5-HTP sustained-release formulation can reduce the damage to their cognitive memory and help them recover. However, administration of 5-HTP alone has no such effect.

[0058] In summary, the 5-HTP nanoparticle-modified oral sustained-release formulation of the present invention has the following biological characteristics: (1) Nanoparticle characteristics: The nanoparticles in this formulation are spherical with uniform particle size of about 200 nm and negative charge on the surface, which helps to improve in vivo stability and bioavailability.

[0059] (2) Release characteristics: The formulation exhibits good sustained-release effect in simulated gastrointestinal fluid and can maintain effective drug concentration in vivo for a long time.

[0060] (3) Pharmacokinetic characteristics: In vivo experiments showed that the 5-HTP of this sustained-release formulation had a longer half-life in serum and the area under the curve was significantly higher than that of ordinary 5-HTP formulation, indicating that it had a better sustained release effect and that the formulation could improve the absorption and utilization of the drug.

[0061] (4) Regulation of 5-HT levels in the brain: In animal models, oral administration of this sustained-release preparation can significantly increase the level of 5-HT in the brain and maintain a high level for a long time, thereby effectively improving insomnia symptoms.

[0062] (5) Neuroprotective effect: In insomnia model mice, the sustained-release formulation can significantly improve the sleep quality of mice and promote the normal function recovery of the nervous system by increasing the level of 5-HT in the brain, and protect neurons from stress damage.

[0063] (6) Biosafety: No obvious adverse reactions were observed in mice after long-term oral administration of the sustained-release formulation, indicating that it has good safety and tolerability.

[0064] (7) Stress resistance: In stress model mice, the sustained-release formulation can significantly alleviate the negative behavioral response caused by stress and promote the improvement of the behavioral performance of mice.

[0065] (8) Synergistic effect: Through nanoparticle modification, 5-HTP forms a stable complex with the carrier, enabling the drug to exert a synergistic effect in vivo, which improves the efficacy of the drug and reduces side effects.

[0066] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing a 5-HTP oral sustained-release formulation, characterized in that, Includes the following steps: S1, 5-HTP and corn starch are dissolved in water to form a mixture. Ethanol solution is added dropwise to the mixture while stirring. Then, the mixture is subjected to ultrasound and rotary evaporation of ethanol to obtain a complex. S2, β-cyclodextrin is added to the complex of step S1 and stirred overnight. After sonication and centrifugation, the supernatant is collected and freeze-dried to obtain a 5-HTP oral sustained-release formulation modified with starch and β-cyclodextrin nanoparticles. The mass ratio of β-cyclodextrin to corn starch is 1:

1.

2. The method according to claim 1, characterized in that, In step S1, the mass ratio of 5-HTP to corn starch is 1:2; In the mixture, the concentration of 5-HTP is 0.1~10 mg / mL, and the concentration of corn starch is 1~50 mg / mL.

3. The method according to claim 1 or 2, characterized in that, In step S1, the concentration of the ethanol solution is 70-75%, the volume ratio of the ethanol solution to the mixture is 1:2-2:1, and the dropping rate of the ethanol solution is 0.1-1 mL / min.

4. A 5-HTP oral sustained-release formulation prepared by the preparation method according to any one of claims 1 to 3, characterized in that, The oral sustained-release formulation of 5-HTP includes a nanocarrier encapsulating 5-HTP. The nanocarrier is composed of corn starch and β-cyclodextrin in a mass ratio of 1:

1. The nanocarrier has an encapsulation rate of 84.58-94.27% for 5-HTP and a loading rate of 62.65-69.83%.

5. A drug comprising the 5-HTP oral sustained-release formulation of claim 4.

6. The use of the 5-HTP oral sustained-release formulation according to claim 4 in the preparation of a drug for treating sleep disorders.

7. The application according to claim 6, characterized in that, The sleep disorders refer to abnormalities in the amount of sleep or abnormal behaviors during sleep.

8. The application according to claim 6, characterized in that, The applications also include: (1) alleviating behavioral abnormalities caused by sleep disorders; (2) Regulate emotional abnormalities caused by sleep disorders, protect the cognitive and memory abilities of individuals with sleep disorders, and restore the ability of central nerve fibers of individuals with sleep disorders to release receptors normally.

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