Nobiletin Attenuates DSS-Induced Intestinal Barrier Damage through the HNF4α-Claudin-7 Signaling Pathway

Nobiletin restores the intestinal barrier of HFD-induced obese mice by promoting MHC-II expression and lipid metabolism

The incidence of obesity is increasing annually worldwide. A high-fat diet (HFD) causes intestinal barrier damage, but effective interventions are currently unavailable. Our previous work demonstrated the therapeutic effect of nobiletin on obese mice; thus, we hypothesized that nobiletin could reverse HFD-induced damage to the intestinal barrier. Male C57BL/6 J mice were orally administered nobiletin for 14 d. After identification, the obese mice were equally divided into three groups: the HFD group, the low-dose (NOL, 100 mg/kg/d) group and the high-dose nobiletin (NOH, 200 mg/kg/d) group. A normal control group (CON) was also included. Hematoxylin and eosin (HE) staining and immunofluorescence were used to observe the intestinal barrier. RT-qPCR was used to determine the transcriptomic levels of genes involved in intestinal barrier integrity and lipid metabolism. The results revealed that intestinal tight proteins, including ZO-1 and Occludin, were significantly reduced in HFD-fed mice but markedly restored after nobiletin intervention, particularly in NOH mice. Improvements in the intestinal barrier and lipid metabolism associated with major histocompatibility complex class II (MHC-II) and relevant elements were revealed after nobiletin intervention. Enrichment analysis revealed that MHC-II plays an important role in the restoration of the intestinal barrier. Taken together, nobiletin restored intestinal barrier integrity and lipid metabolism by regulating MHC-II expression.

Polymethoxylated flavones for modulating signaling pathways in inflammation

Aberrant signaling pathways play a crucial role in the pathogenesis of various diseases, including inflammatory disorders and autoimmune conditions. Polymethoxylated flavones (PMFs), a class of natural compounds found in citrus fruits, have obtained increasing attention for their potential therapeutic effects in modulating inflammatory responses. Although significant progress has been made in the pharmacological research of PMFs, the mechanisms by which they modulate signaling pathways to treat inflammation have not been systematically reviewed or analyzed. To address this gap in the literature, this review explores the mechanisms underlying the anti-inflammatory properties of PMFs and their prospects as drugs for treating inflammatory diseases. We discuss the molecular targets and signaling pathways through which PMFs exert their anti-inflammatory effects, including NF-κB pathway, PI3K/Akt pathway, MAPK pathway, Nrf2 pathway, and regulation of inflammatory cytokine production. Furthermore, we highlight preclinical studies evaluating the efficacy of PMFs in various inflammatory conditions, such as rheumatoid arthritis (RA), inflammatory bowel disease (IBD), and osteoarthritis (OA). Despite promising findings, challenges remain in optimizing the pharmacokinetic properties and therapeutic efficacy of PMFs for clinical use. Future research directions include elucidating the structure-activity relationships of PMFs, developing novel delivery strategies, and conducting large-scale clinical trials to validate their efficacy and safety profiles. Overall, PMFs represent a promising class of natural compounds with potential applications as anti-inflammatory drugs, offering novel therapeutic opportunities for managing inflammatory diseases.

Phytochemical Compounds as Promising Therapeutics for Intestinal Fibrosis in Inflammatory Bowel Disease: A Critical Review

BACKGROUND/OBJECTIVE

Intestinal fibrosis, a prominent consequence of inflammatory bowel disease (IBD), presents considerable difficulty owing to the absence of licensed antifibrotic therapies. This review assesses the therapeutic potential of phytochemicals as alternate methods for controlling intestinal fibrosis. Phytochemicals, bioactive molecules originating from plants, exhibit potential antifibrotic, anti-inflammatory, and antioxidant activities, targeting pathways associated with inflammation and fibrosis. Compounds such as Asperuloside, Berberine, and olive phenols have demonstrated potential in preclinical models by regulating critical signaling pathways, including TGF-β/Smad and NFκB, which are integral to advancing fibrosis.

RESULTS

The main findings suggest that these phytochemicals significantly reduce fibrotic markers, collagen deposition, and inflammation in various experimental models of IBD. These phytochemicals may function as supplementary medicines to standard treatments, perhaps enhancing patient outcomes while mitigating the adverse effects of prolonged immunosuppressive usage. Nonetheless, additional clinical trials are necessary to validate their safety, effectiveness, and bioavailability in human subjects.

CONCLUSIONS

Therefore, investigating phytochemicals may lead to crucial advances in the formulation of innovative treatment approaches for fibrosis associated with IBD, offering a promising avenue for future therapeutic development.

Pterostilbene Alleviates Dextran Sodium Sulfate (DSS)-Induced Intestinal Barrier Dysfunction Involving Suppression of a S100A8-TLR-4-NF-κB Signaling Cascade

Intestinal barrier hemostasis is the key to health. As a resveratrol analogue, pterostilbene (PT) has been reported to prevent dextran sodium sulfate (DSS)-induced intestinal barrier dysfunction mainly associated with the intestinal NF-κB signaling pathway. However, the exact underlying mechanisms are not yet well-defined yet. In this study, we performed RNA-sequencing analysis and unexpectedly found that alarmin S100A8 sensitively responded to DSS-induced intestinal injury. Accordingly, histologic assessments suggested that the high expression of S100A8 was accompanied by increased intestinal infiltration of macrophages, upregulated intestinal epithelial Toll-like receptor 4 (TLR-4), and activated NF-κB signaling pathway. Interestingly, the above phenomena were effectively counteracted upon the addition of PT. Furthermore, by using a coculture system of macrophage THP-1 cells and HT-29 colon cells, we identified macrophage-secreted S100A8 activated intestinal epithelial NF-κB signaling pathway through TLR-4. Taken together, these findings suggested that PT ameliorated DSS-induced intestinal barrier injury through suppression of the macrophage S100A8-intestinal epithelial TLR-4-NF-κB signaling cascade.

Involvement of Bile Acid Metabolism and Gut Microbiota in the Amelioration of Experimental Metabolism-Associated Fatty Liver Disease by Nobiletin

Metabolism-associated fatty liver disease (MAFLD), a growing health problem worldwide, is one of the major risks for the development of cirrhosis and liver cancer. Oral administration of nobiletin (NOB), a natural citrus flavonoid, modulates the gut microbes and their metabolites in mice. In the present study, we established a mouse model of MAFLD by subjecting mice to a high-fat diet (HFD) for 12 weeks. Throughout this timeframe, NOB was administered to investigate its potential benefits on gut microbial balance and bile acid (BA) metabolism using various techniques, including 16S rRNA sequencing, targeted metabolomics of BA, and biological assays. NOB effectively slowed the progression of MAFLD by reducing serum lipid levels, blood glucose levels, LPS levels, and hepatic IL-1β and TNF-α levels. Furthermore, NOB reinstated diversity within the gut microbial community, increasing the population of bacteria that produce bile salt hydrolase (BSH) to enhance BA excretion. By exploring further, we found NOB downregulated hepatic expression of the farnesoid X receptor (FXR) and its associated small heterodimer partner (SHP), and it increased the expression of downstream enzymes, including cholesterol 7α-hydroxylase (CYP7A1) and cytochrome P450 27A1 (CYP27A1). This acceleration in cholesterol conversion within the liver contributes to mitigating MAFLD. The present findings underscore the significant role of NOB in regulating gut microbial balance and BA metabolism, revealing that long-term intake of NOB plays beneficial roles in the prevention or intervention of MAFLD.

Review of recent advances on health benefits, microbial transformations, and authenticity identification of Citri reticulatae Pericarpium bioactive compounds

The extensive health-promoting effects of Citri Reticulatae Pericarpium (CRP) have attracted researchers' interest. The difference in storage time, varieties and origin of CRP are closely related to the content of bioactive compounds they contain. The consitituent transformation mediated by environmental microorganisms (bacteria and fungi) and the production of new bioactive components during the storage process may be the main reason for 'the older, the better' of CRP. In addition, the gap in price between different varieties can be as large as 8 times, while the difference due to age can even reach 20 times, making the 'marketing young-CRP as old-CRP and counterfeiting origin' flood the entire market, seriously harming consumers' interests. However, so far, the research on CRP is relatively decentralized. In particular, a summary of the microbial transformation and authenticity identification of CRP has not been reported. Therefore, this review systematically summarized the recent advances on the main bioactive compounds, the major biological activities, the microbial transformation process, the structure, and content changes of the active substances during the transformation process, and authenticity identification of CRP. Furthermore, challenges and perspectives concerning the future research on CRP were proposed.

Citrus peel ameliorates mucus barrier damage in HFD-fed mice

Citrus peel is rich in bioactive components, especially polyphenols, which are considered to have great potential in the prevention of intestinal diseases. The intestinal mucus barrier is the first defense against the invasion of foreign substances. In this study, we aimed to explore the possibility and mechanism of citrus peel in alleviating the mucus barrier damage in high-fat-diet (HFD) mice. We found that citrus peel powder (CPP) supplementation effectively reduced body weight, fat weight, intestinal permeability, hyperlipidemia, and systemic inflammation in HFD-fed mice. In particular, CPP increased the number of goblet cells, the protein expression of Mucin-2 (Muc2), and the thickness of the mucus layer, thereby strengthening the colonic mucus barrier function. Moreover, CPP supplementation also reduced the expression of endoplasmic reticulum stress (ERS) proteins (GRP78 and CHOP) and increased the expression of T-synthase (O-glycosylation rate-limiting enzyme) and its chaperone protein (Cosmc) in the colon of HFD-fed mice, which suggested that CPP could improve the abnormal protein folding and O-glycosylation of Muc2 during processing and modification. In summary, our study indicates that CPP plays an effective role in relieving mucus barrier damage by improving the production and properties of Muc2, providing new perspectives on the development of CPP as a dietary supplement for strengthening the intestinal barrier.

Bioactive triple peptide inhibits inflammasome activation to alleviate Salmonella-induced intestinal inflammation in mice via modulation of host defense and bacterial virulence

Over the past long period, Salmonella Typhimurium has been an important pathogen that causes intestinal diseases and spells enormous economic shock to animal husbandry all over the world. Pyroptosis and...

Nobiletin and Xanthohumol Sensitize Colorectal Cancer Stem Cells to Standard Chemotherapy

Simple Summary

Colorectal cancer stem cells (CR-CSCs) play a pivotal role in the therapy resistance and relapse of CRC patients. Herein we demonstrate that new treatment approaches comprising polymethoxyflavones and prenylflavonoids extracted from Citrus sinensis and Humulus lupulus, respectively, hamper the viability of CR-CSCs as well as synergizing with 5-fluorouracil and oxaliplatin (FOX)-based chemotherapy. Extract fractions containing Nobiletin and Xanthohumol, in combination with chemotherapy, decreased stemness properties of CR-CSCs and restrained the outgrowth of chemoresistant metastatic CR-CSCs. These data pinpoint Nobiletin and Xanthohumol as efficacious anti-cancer compounds in metastatic settings.

Abstract

Colorectal cancer (CRC) mortality is mainly caused by patient refractoriness to common anti-cancer therapies and consequent metastasis formation. Besides, the notorious toxic side effects of chemotherapy are a concurrent obstacle to be tackled. Thus, new treatment approaches are needed to effectively improve patient outcomes. Compelling evidence demonstrated that cancer stem cells (CSCs) are responsible for treatment failure and relapse. New natural treatment approaches showed capabilities to selectively target the CSC subpopulation by rendering them targetable by standard cytotoxic compounds. Herein we show the anti-cancer properties of the polymethoxyflavones and prenylflavonoids extracted from Citrus sinensis and Humulus lupulus, respectively. The natural biofunctional fractions, singularly and in combination, reduced the cell viability of CRC stem cells (CR-CSCs) and synergized with 5-fluorouracil and oxaliplatin (FOX) chemotherapy. These phenomena were accompanied by a reduced S and G2/M phase of the cell cycle and upregulation of cell death-related genes. Notably, both phytoextracts in combination with FOX thwarted stemness features in CR-CSCs as demonstrated by the impaired clonogenic potential and decreased Wnt pathway activation. Extracts lowered the expression of CD44v6 and affected the expansion of metastatic CR-CSCs in patients refractory to chemotherapy. Together, this study highlights the importance of polymethoxyflavones and prenylflavonoids as natural remedies to aid oncological therapies.

Effects of Wine and Its Microbial-Derived Metabolites on Intestinal Permeability Using Simulated Gastrointestinal Digestion/Colonic Fermentation and Caco-2 Intestinal Cell Models

This paper explores the effects of wine polyphenols on intestinal permeability in in vitro conditions. A red wine (2500 mg/L of gallic acid equivalents) was sequentially subjected to gastrointestinal and colonic digestion in the Dynamic Gastrointestinal Simulator (simgi^®) to obtain two simulated fluids: intestinal-digested wine (IDW) and colonic-digested wine (CDW). The two fluids were incubated with Caco-2 cell monolayers grown in Transwell^® inserts, and paracellular permeability was measured as transport of FITC-dextran. Non-significant decreases (p > 0.05) in paracellular permeability were found, which was attributed to the relatively low phenolic concentration in the solutions tested (15.6 and 7.8 mg of gallic acid equivalents/L for IDW and CDW, respectively) as quercetin (200 µM) and one of its microbial-derived phenolic metabolites, 3,4-dihydroxyphenylacetic acid (200 µM), led to significant decreases (p < 0.05). The expression of tight junction (TJ) proteins (i.e., ZO-1 and occludin) in Caco-2 cells after incubation with IDW and CDW was also determined. A slight increase in mRNA levels for occludin for both IDW and CDW fluids, albeit without statistical significance (p > 0.05), was observed. Analysis of the microbiome and microbial activity during wine colonic fermentation revealed relevant changes in the relative abundance of some families/genera (i.e., reduction in Bacteroides and an increase in Veillonella, Escherichia/Shigella and Akkermansia) as well as in the microbial production of SCFA (i.e., a significant increase in propionic acid in the presence of IDW), all of which might affect paracellular permeability. Both direct and indirect (microbiota-mediated) mechanisms might be involved in the protective effects of (wine) polyphenols on intestinal barrier integrity. Overall, this paper reinforces (wine) polyphenols as a promising dietary strategy to improve gut functionality, although further studies are needed to evaluate the effect on the intestinal barrier under different conditions.

Cldn-7 deficiency promotes experimental colitis and associated carcinogenesis by regulating intestinal epithelial integrity

Intestinal epithelial barrier protects intestine from infection and injury, while chronic inflammation is a trigger for tumorigenesis. As a member of tight junctions (TJs) family, Claudin-7 (Cldn-7) is dedicated to maintaining cell polarity and TJs barrier integrity, and closely related to the development of inflammation and tumors. However, potential roles of Cldn-7 in intestinal inflammation and colitis-associated colorectal cancer (CAC) have not been well characterized in vivo. Here, we analyzed the expression profile of Cldn-7 in inflammatory bowel disease (IBD) and CAC. Colitis and colitis-cancer transformation models were established based on inducible intestinal conditional Cldn-7 gene knockout mice (Cldn7fl/fl;villin-CreERT2), by intraperitoneal injection of azomethane (AOM) and dextran sodium sulfate (DSS) feeding. Cldn-7 knockout promoted susceptibility to colitis and CAC, aggravated clinical symptoms, severely damaged intestinal epithelium, increased mucosal inflammation accompanied dysregulated cell proliferation-apoptosis. Epithelial barrier integrity was destroyed, and intercellular permeability was increased. After AOM/DSS induction, tumor burden and volume were increased, characterized by enhanced proliferation and activation of Wnt/β-catenin signaling pathway. Mechanistically, Cldn-7 deficiency promoted colitis and subsequently malignant transformation by destroying TJs integrity and increasing inflammatory cascade. Overall, based on Cldn-7 knockout mouse model, we have first demonstrated the key roles of Cldn-7 in maintaining intestinal homeostasis and preventing IBD and consequent CAC. Abbreviations: AJs: adherens junctions; AOM: azomethane; Cldn-7: Claudin-7; CRC: colorectal cancer; CAC: colitis-associated colorectal cancer; CD: Crohn's disease; DSS: dextran sodium sulfate; DAI: disease activity index; EMT: epithelial-mesenchymal transition; FITC: fluorescence isothiocyanate; HB: hemoglobin; IBD: inflammatory bowel disease; IECs: intestinal epithelial cells; ISCs: intestinal stem cells; PLT: platelet; RBC: red blood cell; ROS: reactive oxygen species; TAM: tamoxifen; TJs: tight junctions; TCF/LEF: T-cell factor/lymphoid enhancer factor; UC: ulcerative colitis; WBC: white blood cell.

Transcriptome analysis reveals the protective role of fructo-oligosaccharide in colonic mucosal barriers in exercise-induced stressed mice

Most athletes continually endure mental and physical stress from intense exercise. Fructo-oligosaccharide (FOS) can reduce physical exhaustion, but the concrete mechanism behind it still needs further research. In this study, the effect of FOS on colonic mucosal barriers was investigated using an exercise-induced stress mouse model. Except for control individuals, mice were subject to cycles of 2-day exercise (at 20 rpm) interleaved by 5-day rest. The mice experienced a total of 6 days of exercise during the feeding period. FOS improved common indicators of exhaustion, such as glycogen storage in muscle. 16S rRNA data supported that changes in the gut microbiome were also closely related to stress status. Notably, Anaerotruncus was increased in mice under stress, while FOS facilitated the growth of Dorea, which is negatively associated with exhaustion. The RNA-seq analysis revealed that FOS could maintain the integrity of colonic epithelial barriers. For example, FOS significantly restored the expression of tight junctions (Occludin and Zonula occludens-1) in the colon, which was impaired under a stress state. Besides, the NOD-like receptor family pyrin domain containing 6 (NLRP6) inflammasome might contribute to the protection of the colonic mucosa by promoting the secretion of IL-18, Mucin2 (Muc2) and intestine lectin 1 (Itln1) in FOS-treated individuals. In short, FOS administration attenuated the damage of colonic mucosal barriers in exercise-induced stressed mice.

Pterostilbene Ameliorates DSS-Induced Intestinal Epithelial Barrier Loss in Mice via Suppression of the NF-κB-Mediated MLCK-MLC Signaling Pathway

The integrity of the intestinal barrier is critical for homeostasis. In this study, we investigated the protective effect of pterostilbene (PTE) on the intestinal epithelium barrier. In vitro results of transepithelial electrical resistance (TEER) in Caco-2 cells indicated that PTE counteracted tumor necrosis factor α (TNFα)-induced barrier damage. In vivo PTE pretreatment markedly ameliorated intestinal barrier dysfunction induced by dextran sulfate sodium (DSS). Notably, intestinal epithelial tight junction (TJ) molecules were restored by PTE in mice exposed to DSS. The mechanism study revealed that PTE prevented myosin light-chain kinase (MLCK) from driving phosphorylation of MLC (p-MLC), which is crucial for maintaining intestinal TJ stability. Furthermore, PTE blunted translocation of NF-κB subunit p65 into the nucleus to downregulate MLCK expression and then to safeguard TJs and barrier integrity. These findings suggest that PTE protected the intestinal epithelial barrier through the NF-κB- MLCK/p-MLC signal pathway.

The Use of Traditional Chinese Medicine in Relieving EGFR-TKI-Associated Diarrhea Based on Network Pharmacology and Data Mining

In this study, the role of traditional Chinese medicine (TCM) in relieving epidermal growth factor receptor-tyrosine kinase inhibitor- (EGFR-TKI-) associated diarrhea was discussed by network pharmacology and data mining. Prediction of drug targets by introducing the EGFR-TKI molecular structures into the SwissTargetPrediction platform and diarrhea-related targets in the DrugBank, GeneCards, DisGeNET, and OMIM databases were obtained. Compounds in the drug-disease target intersection were screened by absorption, distribution, metabolism, and excretion parameters and Lipinski's rule in Traditional Chinese Medicine Systems Pharmacology. TCM-containing compounds were selected, and information on the property, taste, and meridian tropism of these TCMs was summarized and analyzed. A target-compound-TCM network diagram was constructed, and core targets, compounds, and TCMs were selected. The core targets and components were docked by AutoDock Vina (Version 1.1.2) to explore the target combinations of related compounds and evaluate the docking activity of related targets and compounds. Twenty-three potential therapeutic TCM targets for the treatment of EGFR-TKI-related diarrhea were obtained. There were 339 compounds acting on potential therapeutic targets, involving a total of 402 TCMs. The results of molecular docking showed good binding between the core targets and compounds, and the binding between the core targets and compounds was similar to that of the core target and the recommended drug loperamide. TCMs have multitarget characteristics and are present in a variety of compounds used for relieving EGFR-TKI-associated diarrhea. Antitumor activity and the efficacy of alleviating diarrhea are the pharmacological basis of combining TCMs with EGFR-TKI in the treatment of non-small-cell lung cancer. The core targets, compounds, and TCMs can provide data to support experimental and clinical studies on the relief of EGFR-TKI-associated diarrhea in the future.

Glycation sites and bioactivity of lactose-glycated caseinate hydrolysate in lipopolysaccharide-injured IEC-6 cells

During the thermal processing of milk, Maillard reactions occur between proteins and lactose to generate glycated proteins. In this study, a lactose-glycated caseinate was hydrolyzed by trypsin. The obtained glycated caseinate (GCN) hydrolysate had a lactose content of 10.8 g/kg of protein. We identified its glycation sites and then assessed it for its protective effect against lipopolysaccharide-induced barrier injury using a rat intestinal epithelial cell line (IEC-6 cells) as a cell model and unglycated caseinate (CN) hydrolysate as a reference. Results from our liquid chromatography-mass spectrometry analysis of the GCN hydrolysate verified that lactose glycation occurred at the Lys residues in 3 casein components (α_S1-casein, β-casein, and κ-casein), and this resulted in the formation of 5 peptides with the following amino acid sequences: EMPFPKYPKYPVEPF, HIQKEDVPSE, GSENSEKTTMPL, NQDKTEIPT, and EGIHAQQKEPM. The results from cell experiments showed that the 2 hydrolysates could promote cell growth and decrease lactate dehydrogenase release in the lipopolysaccharide-injured cells; more importantly, they could partially protect the damaged barrier function of the cells by increasing trans-epithelial electrical resistance, decreasing epithelial permeability, and upregulating the expression of the 3 tight junction proteins zonula occludens-1, occludin, and claudin-1. However, compared with CN hydrolysate, GCN hydrolysate showed lower efficacy in protecting against cellular barrier dysfunction. We propose that the different chemical characteristics of the CN hydrolysate and the GCN hydrolysate (i.e., amino acid loss and lactose conjugation) contributed to the lower barrier-protective efficacy of the GCN hydrolysate. During dairy processing, protein glycation of the Maillard type might have a non-negligible, unfavorable effect on dairy proteins, in view of the resulting protein glycation we found and the critical function of proteins for maintaining the integrity of the intestinal barrier.

Citrus flavonoids and the intestinal barrier: Interactions and effects

The intestinal barrier plays a central role in sustaining gut homeostasis and, when dysfunctional, may contribute to diseases. Dietary flavonoids derived from Citrus genus represent one of the main naturally occurring phytochemicals with multiple potential benefits for the intestinal barrier function. In the intestine, citrus flavonoids (CFs) undergo ingestion from the lumen, biotransformation in the epithelial cells and/or crosstalk with luminal microbiota to afford various metabolites that may in turn exert protective actions on gut barrier along with their parental compounds. Specifically, the health-promoting properties of CFs and their metabolic bioactives for the intestinal barrier include their capacity to (a) modulate barrier permeability; (b) protect mucus layer; (c) regulate intestinal immune system; (d) fight against oxidative stress; and (e) positively shape microbiome and metabolome. Notably, local effects of CFs can also generate systemic benefits, for instance, improvement of gut microbial dysbiosis helpful to orchestrate gut homeostasis and leading to alleviation of systemic dysmetabolism. Given the important role of the intestinal barrier in overall health, further understanding of underlying action mechanisms and ultimate health effects of CFs as well as their metabolites on the intestine is of great significance to future application of citrus plants and their bioactives as dietary supplements and/or functional ingredients in medical foods.

Comprehensive Comparison on the Chemical Profile of Guang Chen Pi at Different Ripeness Stages Using Untargeted and Pseudotargeted Metabolomics

The peel of Citrus reticulata 'Chachi' (GCP), which is highly valued in China for its health-promoting effects, is usually collected at different development stages to be processed into various functional foods. In the present work, a rapid method based on ultra-high-performance liquid chromatography Q Exactive Orbitrap mass spectrometry-incorporated untargeted and pseudotargeted metabolomics analysis was developed to investigate the chemical variations in GCP at different ripeness stages. Samples that originated from an individual tree were collected at immature, near mature, and mature stages. A total of 112 compounds were identified or tentatively identified, and flavonoids malonyl glycosides and polymethoxyfolavones glycosides were reported for the first time. Untargeted metabolomics analysis indicated the distinct chemical profiles and significant changes during ripeness stages. Then, a validated pseudotargeted metabolomics method based on parallel reaction monitoring was further applied with a wide coverage of targeted compounds. The GCP samples were found differing in the content variations of flavonoid aglycones, flavonoid O-/C-glycosides, polymethoxyfolavones, limonoids, alkaloids, and phenolic acid, which are important for phenotypic variations at different development stages. The present study is expected to provide new insight on comprehensive utilization of citrus peels at different ripeness stages.