Marine Bioactive Peptides: Anti-Photoaging Mechanisms and Potential Skin Protective Effects.

Skin photoaging, resulting from prolonged exposure to ultraviolet radiation, is a form of exogenous aging that not only impacts the aesthetic aspect of the skin but also exhibits a strong correlation with the onset of skin cancer. Nonetheless, the safety profile of non-natural anti-photoaging medications and the underlying physiological alterations during the process of photoaging remain inadequately elucidated. Consequently, there exists a pressing necessity to devise more secure interventions involving anti-photoaging drugs. Multiple studies have demonstrated the noteworthy significance of marine biomolecules in addressing safety concerns related to anti-photoaging and safeguarding the skin. Notably, bioactive peptides have gained considerable attention in anti-photoaging research due to their capacity to mitigate the physiological alterations associated with photoaging, including oxidative stress; inflammatory response; the abnormal expression of matrix metalloproteinase, hyaluronidase, and elastase; and excessive melanin synthesis. This review provides a systematic description of the research progress on the anti-photoaging and skin protection mechanism of marine bioactive peptides. The focus is on the utilization of marine bioactive peptides as anti-photoaging agents, aiming to offer theoretical references for the development of novel anti-photoaging drugs and methodologies. Additionally, the future prospects of anti-aging drugs are discussed, providing an initial reference for further research in this field.

Application of Thermal Cycling Amplification Chip Method in the Detection of Respiratory Machine-Associated Pneumonia Pathogens.

Objective: Investigating the application effectiveness of using loop-mediated isothermal amplification (LAMP) on a microfluidic chip to detect the pathogens associated with ventilator-associated pneumonia (VAP). Methods: Eighty samples of bronchoalveolar lavage fluid from patients with ventilator-associated pneumonia (VAP) were collected at The First Hospital of Hebei Medical University from July 2022 to July 2023. The bacterial culture technique and the LAMP method were used to detect the nucleic acid of the pathogens in the patient samples. The positivity rates of bacterial culture and LAMP method in detecting VAP pathogens were analyzed. Results: A total of 80 specimens were examined, with 73 positive specimens detected using the LAMP method (positivity rate of 91.25%) and 60 positive specimens detected using bacterial culture (positivity rate of 75.00%). The LAMP method exhibited a higher number of positive detections compared to bacterial culture. Both methods showed a high level of concordance and were virtually identical in detecting methicillin-resistant Staphylococcus aureus, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Haemophilus influenzae, and Streptococcus pneumoniae. Conclusion: The LAMP method demonstrates significantly improved performance in the detection of pathogens for VAP, with a higher pathogen positivity rate compared to bacterial culture. This method holds promising prospects for clinical application.

What factors may affect the effect of ICI-combined therapy in patients with metastatic renal cell carcinoma? A meta-analysis.

OBJECTIVE: The prognostic factors of ICI-including combined therapy in patients with metastatic renal cell carcinoma were analyzed by systematic review. METHOD: We searched Web of Science, Cochrane, PubMed, CNKI, Wanfang and other databases for randomized controlled trials and clinical trials of combination therapy including ICIs in the treatment of metastatic renal cell carcinoma. The search time was from the establishment of the database to September 2023. Data were extracted and evaluated with RevMan 5.4 software. RESULTS: Six studies were included, including 4723 patients. The results showed that ① in terms of progression-free survival, the factors of age < 65 years old, male sex, Canada and Western Europe, nephrectomy, different IMDC class, number of organs with metastases and PD-L1 expression ≥ 1% significantly prolonged PFS in patients with metastatic cancer treated by combination therapy including ICIs; ② in terms of overall survival rate, the factors of age < 65 years old, female sex, nephrectomy, different IMDC class and PD-L1 expression ≥ 1% significantly prolonged the OS of patients with metastatic cancer treated by combination therapy including ICIs. CONCLUSIONS: Age, sex, region, nephrectomy, different IMDC class, number of organs with metastases and PD-L1 expression are independent factors influencing the efficacy of combination therapy including ICIs in the treatment of metastatic renal cell carcinoma. Systematic evaluation of baseline indicators of patients with metastatic renal cell carcinoma to predict clinical benefits can effectively improve the benefit rate of patients.

Inhibitory Activity and Mechanism of High-Voltage Prick Electric Field Against Salmonella enteritidis on Gelatin Plates and Selected Food Systems.

The present study assesses the antibacterial effect of a high-voltage prick electric field (HVPEF) on Salmonella enteritidis on gelatin plates and selected food systems. The results showed that S. enteritidis were susceptible to HVPEF treatment, with a mortality rate of 98% on the gelatin plate at 13 kV for 15 min. The survival rate of S. enteritidis decreased linearly with time and then stabilized after a sharp decline. The morphological change and the loss of internal nucleic acids and proteins suggest that the cell membrane was damaged by HVPEF, appearing more permeable and less fluid. Compared with the untreated group, both reactive oxygen species (ROS) and malondialdehyde increased significantly in the treated groups. Flow cytometry results suggest that DNA was severely damaged, which led to cell death, as shown by the elevated levels of intracellular ROS and lipid peroxidation. The death rate of S. enteritidis on the food surface significantly rose with the increase of HVPEF intensity, reaching 91 ± 1.6% (salmon), 88.2 ± 2.2% (chicken breast), 72.9 ± 2.7% (sausage), and 66.9 ± 1.6% (steak), respectively, at 14 kV for 30 min. HVPEF resulted in no significant change in color or texture; the changes in total viable count and pH were less significant than in the untreated group. Finally, HVPEF treatment led to lower levels of total volatile base nitrogen and thiobarbituric acid reactive substances in chicken breasts, which potentially contributes to longer shelf life.

Nitrogen-doped orange emitting carbon dots for ß-carotene detection and lysosomal imaging.

ß-Carotene is a natural antioxidant that has an indispensable effect on the growth and immunity of the human body. For intracellular and in vitro detection of ß-carotene, N-doped carbon quantum dots (O-CDs) were prepared by co-heating carbonization of 1,5-naphthalenediamine and nitric acid in ethanol solvent for 2 h at 200 °C. O-CDs have longer wavelength orange light emission, with an optimal excitation peak of 470 nm and an optimal emission peak of 590 nm. According to the principle of the internal filtering effect on which the detection system is based, O-CDs present a good linear relationship with ß-carotene within a wide range of 0-2000 µM, and the R2 coefficient of the linear regression equation is 0.999. In addition, O-CDs showed targeting of lysosomes in cell imaging and could be used to detect intracellular lysosomal movement. These experiments show that O-CDs can be used for in vivo and in vitro detection of ß-carotene and can serve as a potential substitute to commercial lysosome targeting probes.

Bipolar Membrane Electrodialysis for Direct Conversion of L-Ornithine Monohydrochloride to L-Ornithine.

In this study, bipolar membrane electrodialysis was proposed to directly convert L-ornithine monohydrochloride to L-ornithine. The stack configuration was optimized in the BP-A (BP, bipolar membrane; A, anion exchange membrane) configuration with the Cl- ion migration through the anion exchange membrane rather than the BP-A-C (C, cation exchange membrane) and the BP-C configurations with the L-ornithine+ ion migration through the cation exchange membrane. Both the conversion ratio and current efficiency follow BP-A > BP-A-C > BP-C, and the energy consumption follows BP-A < BP-A-C < BP-C. Additionally, the voltage drop across the membrane stack (two repeating units) and the feed concentration were optimized as 7.5 V and 0.50 mol/L, respectively, due to the low value of the sum of H+ ions leakage (from the acid compartment to the base compartment) and OH- ions migration (from the base compartment to the acid compartment) through the anion exchange membrane. As a result, high conversion ratio (96.1%), high current efficiency (95.5%) and low energy consumption (0.31 kWh/kg L-ornithine) can be achieved. Therefore, bipolar membrane electrodialysis is an efficient, low energy consumption and environmentally friendly method to directly convert L-ornithine monohydrochloride to L-ornithine.

Characteristics of Gaseous/Liquid Hydrocarbon Adsorption Based on Numerical Simulation and Experimental Testing.

Hydrocarbon vapor adsorption experiments (HVAs) are one of the most prevalent methods used to evaluate the proportion of adsorbed state oil, critical in understanding the recoverable resources of shale oil. HVAs have some limitations, which cannot be directly used to evaluate the proportion of adsorbed state oil. The proportion of adsorbed state oil from HVA is always smaller than that in shale oil reservoirs, which is caused by the difference in adsorption characteristics of liquid and gaseous hydrocarbons. The results of HVA need to be corrected. In this paper, HVA was conducted with kaolinite, an important component of shale. A new method is reported here to evaluate the proportion of adsorbed state oil. Molecular dynamics simulations (MDs) of gaseous/liquid hydrocarbons with the same temperature and pressure as the HVAs were used as a reference to reveal the errors in the HVAs evaluation from the molecular scale. We determine the amount of free state of hydrocarbons by HVAs, and then calculate the proportion of adsorbed state oil by the liquid hydrocarbon MD simulation under the same conditions. The results show that gaseous hydrocarbons adsorptions are monolayer at low relative pressures and bilayer at high relative pressures. The liquid hydrocarbons adsorption is multilayer adsorption. The adsorption capacity of liquid hydrocarbons is over 2.7 times higher than gaseous hydrocarbons. The new method will be more effective and accurate to evaluate the proportion of adsorbed state oil.

Antibacterial Efficacy and Mechanisms of Curcumin-Based Photodynamic Treatment against Staphylococcus aureus and Its Application in Juices.

Antimicrobial Photodynamic Treatment (aPDT) is a non-thermal sterilization technology, which can inactivate common foodborne pathogens. In the present study, photodynamic inactivation on Staphylococcus aureus (S. aureus) with different concentrations of curcumin and light dose was evaluated and the mechanisms were also investigated. The results showed that curcumin-based aPDT could inactivate S. aureus cells by 6.9 log CFU/mL in phosphate buffered saline (PBS). Moreover, the modified Gompertz model presented a good fit at the inactivation data of S. aureus. Photodynamic treatment caused cell membrane damage as revealed by analyzing scanning electron microscopy (SEM) images. Leakage of intracellular constituents further indicated that cell membrane permeability was changed. Flow cytometry with double staining demonstrated that cell membrane integrity and the activity of nonspecific esterase were destroyed. Compared with the control group, intracellular reactive oxygen species (ROS) levels caused by photodynamic treatment significantly increased. Furthermore, curcumin-based aPDT reduced S. aureus by 5 log CFU/mL in juices. The color of the juices was also tested using a Chromatic meter, and it was found that b* values were the most markedly influenced by photodynamic treatment. Overall, curcumin-based aPDT had strong antibacterial activity against S. aureus. This approach has the potential to remove foodborne pathogens from liquid food.

The effect of Telmisartan on the expression of connexin43 and neointimal hyperplasia in a rabbit iliac artery restenosis model.

We established a rabbit iliac artery restenosis model to explore the impact of Telmisartan on the expression of Connexin43 (Cx43) and neointimal hyperplasia. Thirty New Zealand white rabbits were randomly divided into three groups: control group (n = 10), restenosis group (n = 10), and Telmisartan group (n = 10). The restenosis model was established by high-cholesterol diet combined with double-balloon injury of iliac arteries. In addition, Telmisartan at 5 mg/(kg day) was administered to the rabbits of Telmisartan group on the second day after the second balloon injury. All rabbits were killed at the end of the experiment followed by institution policy. Before sacrifice, blood samples were obtained to test serum angiotensinII (AngII). Iliac arteries were isolated for morphological analysis and determining the expression of Cx43 by HE staining, immunohistochemical analysis, reverse transcription-polymerase chain reaction (RT-PCR), and Western Blotting analysis. Then, the local AngII levels of arteries were measured by radioimmunoassay. As compared with controls, the expression of Cx43 mRNA (0.98 ± 0.08) vs. (1.27 ± 0.17), P < 0.01), and Cx43 protein [(0.75 ± 0.08) vs. (0.90 ± 0.08), P < 0.05] of restenosis group were increased, which were significantly higher than those of Telmisartan group [Cx43 mRNA: (1.27 ± 0.17) vs. (1.00 ± 0.20), P < 0.01; Cx43 protein: (0.90 ± 0.08) vs. (0.82 ± 0.05), P < 0.05]. Furthermore, The intima thickness [(266.12 ± 70.27) vs. (2.85 ± 0.19) µm, P < 0.01] and the local AngII [(115.6 ± 15.7) vs. (90.1 ± 7.7), P < 0.05] of restenosis group were raised when compared with controls. Telmisartan group exhibited thinner intima compared with restenosis group [(68.22 ± 24.37) vs. (266.12 ± 70.27), P < 0.01]. However, the local AngII levels between these two groups were approximate. In addition, the plasma concentration of AngII was not significantly different among three groups. In conclusion, Telmisartan can inhibit the expression of connexin43 and neointimal hyperplasia in iliac artery restenosis model.

New Experimental Limits on Exotic Spin-Spin-Velocity-Dependent Interactions by Using SmCo_{5} Spin Sources.

Despite the great success of the standard model (SM), there still exist mysteries like the nature of dark matter, the strong CP problems, etc. To solve them, many theories proposed new bosons beyond the SM that can mediate new forces. Here, we report the latest results of searching for possible new long-range spin-spin-velocity-dependent forces (SSVDFs), based on specially designed iron-shielded SmCo_{5} spin sources and a spin exchange relaxation free comagnetometer. With help from the similarity analysis method, new constraints on some forms of SSVDFs between electrons have been obtained, which represent up to more than 11 orders of magnitude tighter limits than previous experiments for the force range of 5 cm-1 km.

Toxicogenomic evaluation of liver responses induced by acrylamide and glycidamide in male mouse liver.

In current studies, histopathologic method, Agilent GeneChip hybridization and Western blot were used to investigate the toxicity of acrylamide (AA) and glycidamide (GA) in male mouse livers. The histopathologic results demonstrated that AA and GA could cause oxidative damage to mouse liver. Middle dose of GA and AA (50 mg/kg b.w./day) could significantly up-regulate the expression of cytochrome P450, as well as genes related to oxidative injury, cancer and inflammation, and significantly down-regulate the expression of genes related to anti-apoptosis, antioncogene and fatty acid synthesis. Middle and high dose (75 mg/kg b.w./day) of GA and AA could both down-regulate the expression of hepatic anti-oncogene Bcl2 and up-regulate the expression of cancer-related gene Rad51 and EGFR protein. The expression of anti-oncogene P21 induced by AA and GA was decreased. Our current study demonstrated that the oxidative damage, immune injury and carcinogenicity of mouse liver samples could be induced by AA and GA at histopathological, entire genome and protein levels.

Protective effect of allicin against glycidamide-induced toxicity in male and female mice.

Acrylamide is known to be a neurotoxic, genotoxic, and carcinogenic compound. Glycidamide has a close relationship to the toxic mechanism of acrylamide. In order to explore the toxic mechanism of acrylamide, we further discussed the effects of oral administration of allicin on glycidamide-induced toxicity by determining the hematological parameters like AST, ALT, LDH, BUN, creatinine, ROS, and 8-OHdG, and biochemical parameters such as MDA, MPO, SOD, GST and GSH in the kidney, liver, brain and lung of male and female mice for the first time. We found that the same dose of glycidamide had more toxic effects and damage effects to the mice compared to the previous study of acrylamide. It could markedly increase the level of AST, ALT, LDH, BUN, ROS, 8-OHdG, MDA, MPO while decrease the SOD, GST and GSH. However, our data showed the oral administered allicin with a concentration of 5, 10, and 20 mg/kg b.w./day could significantly decrease the damage indexes of AST, ALT, LDH, BUN, ROS, 8-OHdG, MDA, and MPO, while increase the antioxidant indicators of SOD, GST and GSH. Thus allicin could be used as an effective dietary supplement for the chemoprevention of glycidamide genotoxicity internally, and to prevent the tissue damage and toxicity induced by glycidamide.

Protective effects of phillyrin on H2O 2-induced oxidative stress and apoptosis in PC12 cells.

Oxidative stress is a major component of harmful cascades activated in neurodegenerative disorders. We sought to elucidate possible effects of phillyrin, an active constituent isolated from the Chinese medicinal herb Forsythia suspense, on hydrogen peroxide (H2O2)-induced cell death and determine the underlying molecular mechanisms in neuron-like PC12 cells. By MTT assay and lactate dehydrogenase (LDH) leakage assay, we found that phillyrin treatment effectively protected PC12 cells against H2O2-induced cell damage. H2O2 exposure induced oxidative stress in PC12 cells, as revealed by enhanced oxidative stress and decreased activities of antioxidative enzymes, which were inhibited by phillyrin pretreatment. ROS activated mitochondria-dependent apoptosis. The anti-apoptotic effects of phillyrin were also confirmed by acridine orange/ethidium bromide (AO/EB) staining. Mitochondrial membrane potential decrease, cytochrome c release, caspases activation, activation of AIF and Endo G were observed in H2O2-treated cells by rhodamine 123 or western blot. Interestingly, phillyrin effectively suppressed these changes. Moreover, phillyrin could inhibit H2O2-induced up-regulation of Bax/Bcl-2 ratio. In conclusion, phillyrin effectively inhibited H2O2-induced oxidative stress and apoptosis in PC12 cells.

Salidroside Alleviates Furan-Induced Impaired Gut Barrier and Inflammation via Gut Microbiota-SCFA-TLR4 Signaling.

As a food contaminant that can be quickly absorbed through the gastrointestinal system, furan has been shown to disrupt the intestinal flora and barrier. Investigation of the intestinal toxicity mechanism of furan is of great significance to health. We previously identified the regulatory impact of salidroside (SAL) against furan-provoked intestinal damage, and the present work further explored whether the alleviating effect of SAL against furan-caused intestinal injury was based on the intestinal flora; three models, normal, pseudo-germ-free, and fecal microbiota transplantation (FMT), were established, and the changes in intestinal morphology, barrier, and inflammation were observed. Moreover, 16S rDNA sequencing observed the variation of the fecal flora associated with inflammation and short-chain fatty acids (SCFAs). Results obtained from the LC-MS/MS suggested that SAL increased furan-inhibited SCFA levels, activated the mRNA expressions of SCFA receptors (GPR41, GPR43, and GPR109A), and inhibited the furan-activated TLR4/MyD88/NF-κB signaling. Analysis of protein-protein interaction further confirmed the aforementioned effects of SAL, which inhibited furan-induced barrier damage and intestinal inflammation.

CALCR exacerbates renal cell carcinoma progression via stabilizing CD44.

The calcitonin receptor (CALCR) is an essential protein for maintaining calcium homeostasis and has been reported to be upregulated in numerous cancers. However, the molecular role of CALCR in renal cell carcinoma (RCC) is not well understood. In this study, we identified the overexpression of CALCR in RCC using human tissue chip by immunohistochemical (IHC) staining, which was associated with a poor prognosis. Functionally, CALCR depletion inhibited RCC cell proliferation and migration, and induced cell apoptosis and cycle arrest. CALCR is also essential for in vivo tumor formation. Mechanistically, we demonstrated that CALCR could directly bind to CD44, preventing CD44 protein degradation and thereby upregulating CD44 expression. Moreover, a deficiency in CD44 significantly attenuated the promoting role of CALCR on RCC cell proliferation, migration and anti-apoptosis capacities. Collectively, CALCR exacerbates RCC progression via stabilizing CD44, offering a fundamental basis for considering CALCR as a potential therapeutic target for RCC patients.

Mechanism of apoptosis induced by the combined action of acrylamide and Elaidic acid through endoplasmic reticulum stress injury.

Thermal processing of food is likely to form acrylamide (AA) and elaidic acid (EA), which are both mainly metabolized by the liver. The two substances are associated with the pathogenesis of liver disease. In the current study, we investigated the toxic effects of the combined action of AA and EA on HSC-T6 cells, and the mechanism of apoptosis exacerbated by the co-exposure. The results showed a synergistic effect of AA and EA, which exacerbated the damage and oxidative stress (OS) in HSC-T6. Meanwhile, the expression of endoplasmic reticulum stress (ERS) proteins, such as GRP78 and CHOP, was increased, the ERS pathway was activated, and Ca2+ in cells was increased, which exacerbated mitochondrial damage, and opened IP3R-Grp75-VDAC1 channel. Both ERS and mitochondrial damage caused the process of cell apoptosis. Inhibition of ERS by 4-phenylbutyric acid (4-PBA) significantly reversed the synergistic effects on mitochondrial damage via ERS, suggesting that AA and EA exacerbated mitochondrial damage through ERS-mediated Ca2+ overload. AA and EA synergistically damaged the function of mitochondria through exacerbating ERS and led to cell apoptosis.

Establishment of the microscope incubation system and its application in evaluating tumor treatment effects through real-time live cellular imaging.

Introduction: Long-term imaging of live cells is commonly used for the study of dynamic cell behaviors. It is crucial to keep the cell viability during the investigation of physiological and biological processes by live cell imaging. Conventional incubators that providing stable temperature, carbon dioxide (CO2) concentration, and humidity are often incompatible with most imaging tools. Available commercial or custom-made stage-top incubators are bulky or unable to provide constant environmental conditions during long time culture. Methods: In this study, we reported the development of the microscope incubation system (MIS) that can be easily adapted to any inverted microscope stage. Incremental PID control algorithm was introduced to keep stable temperature and gas concentration of the system. Moreover, efficient translucent materials were applied for the top and bottom of the incubator which make it possible for images taken during culture. Results: The MIS could support cell viability comparable to standard incubators. When used in real time imaging, the MIS was able to trace single cell migration in scratch assay, T cell mediated tumor cells killing in co-culture assay, inflation-collapse and fusion of organoids in 3D culture. And the viability and drug responses of cells cultured in the MIS were able to be calculated by a label-free methods based on long term imaging. Discussion: We offer new insights into monitoring cell behaviors during long term culture by using the stage adapted MIS. This study illustrates that the newly developed MIS is a viable solution for long-term imaging during in vitro cell culture and demonstrates its potential in cell biology, cancer biology and drug discovery research where long-term real-time recording is required.

Salidroside Ameliorates Furan-Induced Testicular Inflammation in Relation to the Gut-Testis Axis and Intestinal Apoptosis.

Furan is a heat-induced food contaminant, and it causes damage to visceral organs, including the testis. To determine the mechanism of the damage to the testis, a mouse model treated with furan (8 mg/kg bw/day) and salidroside (SAL, 10/20/40 mg/kg bw/day) was established, and levels of testicular functional markers and changes of morphology were investigated in furan-induced mice treated with SAL. The change in related proteins and genes suggested that SAL restored the furan-mediated leaky tight junction and triggered the TLR4/MyD88/NF-κB pathway and NLRP3 inflammasome together with inflammation. To find out the gut-testis axis, microbiota PICRUSt analysis and correlation analysis were conducted to investigate the core microbiota and metabolites. The endoplasmic reticulum stress (ERS)-related key protein levels and the result of transmission electron microscopy suggested that SAL inhibited the furan-induced intestinal ERS. The result of TUNEL and levels of apoptosis-related proteins suggested that furan-induced intestinal apoptosis was alleviated by SAL. Collectively, SAL inhibited furan-induced ERS-mediated intestinal apoptosis through modulation of intestinal flora and metabolites, thus strengthening the gut barrier. It inhibited LPS from entering the circulatory system and suppressed the testicular TLR4/MyD88/NF-κB pathway and NLRP3 inflammasome, which alleviated testicular inflammation.

Fabrication of grape seed proanthocyanidin-loaded W/O/W emulsion gels stabilized by polyglycerol polyricinoleate and whey protein isolate with konjac glucomannan: Structure, stability, and in vitro digestion.

In this work, the effects of konjac glucomannan (KGM) concentrations on microstructure, gel properties, stability and digestibility of water-in-oil-in-water emulsion gels stabilized by polyglycerol polyricinoleate and whey protein isolate were investigated. Visual appearance indicated that a non-layered double emulsion gel was formed when KGM increased to 0.75%. Emulsion gels with 1.5% KGM showed the highest encapsulation, freeze-thaw and photochemical stability due to the formation of the smallest droplets, which were supported by microscopic observations. Moreover, the addition of KGM improved water holding capacity, rheological and texture properties of emulsion gels. Particularly, at 1.5% or 1.75% KGM, color and potential of hydrogen showed the most stable level after 14 days of storage. During in vitro digestion, KGM delayed the hydrolysis of protein and oil droplets, and then improved the bioavailability of grape seed proanthocyanidin. These results promoted the application of KGM in emulsion gels and the encapsulation of nutraceuticals.

Amino acids as methyl donors for the formation of N,N-dimethylpiperidinium (mepiquat) in model systems and cooked mushrooms.

In the present study, new methylating agents for the formation of N,N-dimethylpiperidinium (mepiquat) were evaluated in both model and mushroom systems. Mepiquat levels were monitored using five model systems; alanine (Ala)/pipecolic acid (PipAc), methionine (Met)/PipAc, valine (Val)/PipAc, leucine (Leu)/PipAc, and isoleucine (Ile)/PipAc. The highest level of mepiquat was 1.97% at 260 °C for 60 min (Met/PipAc model system). Piperidine can actively combine with methyl groups in thermal reactions to form N-methylpiperidine and mepiquat. Additionally, mushrooms rich in amino acids were oven baked, pan cooked, and deep fried, respectively, to investigate the formation of mepiquat. Oven baking led to the highest mepiquat content of 63.22 ± 0.88 µg/kg. In summary, food constituents are the main source of precursors for mepiquat formation, the mechanism of which has been presented in both model systems and mushroom matrices rich in amino acids.