Tamoxifen upregulates the peroxisomal ß-oxidation enzyme Enoyl CoA hydratase and 3-hydroxyacyl CoA hydratase ameliorating hepatic lipid accumulation in mice.

Tamoxifen is an estrogen receptor modulator that has been reported to alleviate hepatic lipid accumulation in mice, but the mechanism is still unclear. Peroxisome fatty acid ß-oxidation is the main metabolic pathway for the overload of long-chain fatty acids. As long-chain fatty acids are a cause of hepatic lipid accumulation, the activation of peroxisome fatty acid ß-oxidation might be a novel therapeutic strategy for metabolic associated fatty liver disease. In this study, we investigated the mechanism of tamoxifen against hepatic lipid accumulation based on the activation of peroxisome fatty acid ß-oxidation. Tamoxifen reduced liver long-chain fatty acids and relieved hepatic lipid accumulation in high fat diet mice without sex difference. In vitro, tamoxifen protected primary hepatocytes against palmitic acid-induced lipotoxicity. Mechanistically, the RNA-sequence of hepatocytes isolated from the liver revealed that peroxisome fatty acid ß-oxidation was activated by tamoxifen. Protein and mRNA expression of enoyl CoA hydratase and 3-hydroxyacyl CoA hydratase were significantly increased in vivo and in vitro. Small interfering RNA enoyl CoA hydratase and 3-hydroxyacyl CoA hydratase in primary hepatocytes abolished the therapeutic effects of tamoxifen in lipid accumulation. In conclusion, our results indicated that tamoxifen could relieve hepatic lipid accumulation in high fat diet mice based on the activation of enoyl CoA hydratase and 3-hydroxyacyl CoA hydratase-mediated peroxisome fatty acids ß-oxidation.

Oncofetal SNRPE promotes HCC tumorigenesis by regulating the FGFR4 expression through alternative splicing.

BACKGROUND: Due to insufficient knowledge about key molecular events, Hepatocellular carcinoma (HCC) lacks effective treatment targets. Spliceosome-related genes were significantly altered in HCC. Oncofetal proteins are ideal tumor therapeutic targets. Screening of differentially expressed Spliceosome-related oncofetal protein in embryonic liver development and HCC helps discover effective therapeutic targets for HCC. METHODS: Differentially expressed spliceosome genes were analysis in fetal liver and HCC through bioinformatics analysis. Small nuclear ribonucleoprotein polypeptide E (SNRPE) expression was detected in fetal liver, adult liver and HCC tissues. The role of SNRPE in HCC was performed multiple assays in vitro and in vivo. SNRPE-regulated alternative splicing was recognized by RNA-Seq and confirmed by multiple assays. RESULTS: We herein identified SNRPE as a crucial oncofetal splicing factor, significantly associated with the adverse prognosis of HCC. SOX2 was identified as the activator for SNRPE reactivation. Efficient knockdown of SNRPE resulted in the complete cessation of HCC tumorigenesis and progression. Mechanistically, SNRPE knockdown reduced FGFR4 mRNA expression by triggering nonsense-mediated RNA decay. A partial inhibition of SNRPE-induced malignant progression of HCC cells was observed upon FGFR4 knockdown. CONCLUSIONS: Our findings highlight SNRPE as a novel oncofetal splicing factor and shed light on the intricate relationship between oncofetal splicing factors, splicing events, and carcinogenesis. Consequently, SNRPE emerges as a potential therapeutic target for HCC treatment. Model of oncofetal SNRPE promotes HCC tumorigenesis by regulating the AS of FGFR4 pre-mRNA.

Targeting Moonlighting Enzymes in Cancer.

Moonlighting enzymes are multifunctional proteins that perform multiple functions beyond their primary role as catalytic enzymes. Extensive research and clinical practice have demonstrated their pivotal roles in the development and progression of cancer, making them promising targets for drug development. This article delves into multiple notable moonlighting enzymes, including GSK-3, GAPDH, and ENO1, and with a particular emphasis on an enigmatic phosphatase, PTP4A3. We scrutinize their distinct roles in cancer and the mechanisms that dictate their ability to switch roles. Lastly, we discuss the potential of an innovative approach to develop drugs targeting these moonlighting enzymes: target protein degradation. This strategy holds promise for effectively tackling moonlighting enzymes in the context of cancer therapy.

Design, synthesis, and biological evaluation of first-in-class FABP1 inhibitors for the treatment of NASH.

The fatty acid-binding protein 1 (FABP1) is a fatty acid transporter protein that is considered as an emerging target for metabolic diseases. Despite forceful evidence that the inhibition of FABP1 is essential for ameliorating NASH, pharmacological control and validation of FABP1 are hindered by a lack of relevant inhibitors as pharmacological tool. Therefore, the development of effective FABP1 inhibitors is a current focus of research. Herein, we firstly reported the comprehensive structure-activity relationship (SAR) study of novel FABP1 inhibitors derived from high throughput screening of our in-house library, which resulting in the identification of the optimal compound 44 (IC50 = 4.46 ± 0.54 µM). Molecular docking studies revealed that 44 forms stable hydrogen bonds with amino acids around the active pocket of FABP1. Moreover, 44 alleviated the typical histological features of fatty liver in NASH mice, including steatosis, lobular inflammation, ballooning and fibrosis. Additionally, 44 has been demonstrated to have lipid metabolism regulating, anti-oxidative stress and hepatoprotective properties. This study might be provided a promising insight into the field of NASH and inspiration for the development of FABP1 inhibitors.

Tetrahedral framework nucleic acids for improving wound healing.

Wounds are one of the most common health issues, and the cost of wound care and healing has continued to increase over the past decade. In recent years, there has been growing interest in developing innovative strategies to enhance the efficacy of wound healing. Tetrahedral framework nucleic acids (tFNAs) have emerged as a promising tool for wound healing applications due to their unique structural and functional properties. Therefore, it is of great significance to summarize the applications of tFNAs for wound healing. This review article provides a comprehensive overview of the potential of tFNAs as a novel therapeutic approach for wound healing. In this review, we discuss the possible mechanisms of tFNAs in wound healing and highlight the role of tFNAs in modulating key processes involved in wound healing, such as cell proliferation and migration, angiogenesis, and tissue regeneration. The targeted delivery and controlled release capabilities of tFNAs offer advantages in terms of localized and sustained delivery of therapeutic agents to the wound site. In addition, the latest research progress on tFNAs in wound healing is systematically introduced. We also discuss the biocompatibility and biosafety of tFNAs, along with their potential applications and future directions for research. Finally, the current challenges and prospects of tFNAs are briefly discussed to promote wider applications.

AgAu-modified quasi-MIL-53 hybrid nanozymes with triple enzyme-like activities for boosting biocatalytic disinfection.

Metal-organic frameworks (MOFs) have great potential for combating pathogenic bacterial infections and are expected to become an alternative to antibiotics. However, organic linkers obstruct and saturate the inorganic nodes of MOF structures, making it challenging to utilize the applied potential of metal centers. Here, we combined controlled ligand decarboxylation with noble metal nanoparticles to rationally remodel MIL-53, resulting in a hybrid nanozyme (AgAu@QMIL-53, AAQM) with excellent multiple enzyme-like activities that both eradicate bacteria and promote diabetic wound healing. Specifically, benefitting from oxidase (OXD)-like and peroxidase (POD)-like activities, AAQM converts oxygen (O2) and hydrogen peroxide (H2O2) into superoxide anion radicals (O2-) and hydroxyl radicals (OH) to eradicate bacteria. In in vitro antibacterial experiments, AAQM exhibited favorable killing efficacy against Pseudomonas aeruginosa (P. aeruginosa) and methicillin-resistant Staphylococcus aureus (MRSA) (>99 %). Notably, due to its superoxide (SOD)-like activity and outstanding reactive nitrogen species (RNS) elimination capacity, AAQM can produce adequate O2 and alleviate oxidative stress in diabetic wounds. Benefiting from the rational modification of MIL-53, the synthesized hybrid nanozyme can effectively kill bacteria while alleviating oxidative stress and ultimately promote infected diabetic wound healing. Overall, this biomimetic enzyme-catalyzed strategy will bring enlightenment to the design of self-antibacterial agents for efficient disinfection and wound healing simultaneously.

Group 1 innate lymphoid cell activation via recognition of NKG2D and liver resident macrophage MULT-1: Collaborated roles in triptolide induced hepatic immunotoxicity in mice.

Triptolide (TP) is the major bioactive component of traditional Chinese medicine Tripterygium wilfordii Hook. F., a traditional Chinese medicinal plant categorized within the Tripterygium genus of the Celastraceae family. It is recognized for its therapeutic potential in addressing a multitude of diseases. Nonetheless, TP is known to exhibit multi-organ toxicity, notably hepatotoxicity, which poses a significant concern for the well-being of patients undergoing treatment. The precise mechanisms responsible for TP-induced hepatotoxicity remain unresolved. In our previous investigation, it was determined that TP induces heightened hepatic responsiveness to exogenous lipopolysaccharide (LPS). Additionally, natural killer (NK) cells were identified as a crucial effector responsible for mediating hepatocellular damage in this context. However, associated activating receptors and the underlying mechanisms governing NK cell represented innate lymphoid cell (ILC) activation remained subjects of inquiry and were not yet investigated. Herein, activating receptor Killer cell lectin like receptor K1 (NKG2D) of group 1 ILCs was specifically upregulated in TP- and LPS-induced acute liver failure (ALF), and in vivo blockade of NKG2D significantly reduced group 1 ILC mediated cytotoxicity and mitigated TP- and LPS-induced ALF. NKG2D ligand UL16-binding protein-like transcript 1 (MULT-1) was found upregulated in liver resident macrophages (LRMs) after TP administration, and LRMs did exhibit NK cell activating effect. Furthermore, M1 polarization of LRMs cells was observed, along with an elevation in intracellular tumor necrosis factor (TNF)-α levels. In vivo neutralization of TNF-α significantly alleviated TP- and LPS-induced ALF. In conclusion, the collaborative role of group 1 ILCs and LRMs in mediating hepatotoxicity was confirmed in TP- and LPS-induced ALF. TP-induced MULT-1 expression in LRMs was the crucial mechanism in the activation of group 1 ILCs via MULT-1-NKG2D signal upon LPS stimulation, emphasizing the importance of infection control after TP administration.

CHIR-98014, a GSK 3ß Inhibitor, Protects Against Triptolide/Lipopolysaccharide-Induced Hepatotoxicity by Mitochondria-Dependent Apoptosis Inhibition.

Triptolide (TP) is a remarkable anti-inflammatory and immunosuppressive component separated from Tripterygium wilfordii Hook. F. However, its hepatotoxicity limits its application in the clinical. Our group has proposed a new perspective on TP-induced hepatotoxicity, in which TP enhances liver hypersensitivity upon lipopolysaccharide (LPS) stimulation. Because the cause of the disease is unknown, there is currently no uniform treatment available. In this study, we attempted to determine whether the GSK-3ß-JNK pathway affects liver damage and its regulatory mechanism in response to TP/LPS costimulation. In addition, we investigated the effect of CsA or the GSK 3ß inhibitor CHIR-98014 on TP/LPS-induced hepatotoxicity. The results showed that the TP/LPS cotreatment mice exhibited obvious hepatotoxicity, as indicated by a remarkable increase in the serum ALT and AST levels, glycogen depletion, GSK 3ß-JNK upregulation, and increased apoptosis. Instead of the specific knockdown of JNK1, the specific knockdown of JNK2 had a protective effect. Additionally, 40 mg/kg of CsA and 30 mg/kg of CHIR-98014 might provide protection. In summary, CHIR-98014 could protect against TP/LPS- or TP/TNF-α-induced activation of the GSK 3ß-JNK pathway and mitochondria-dependent apoptosis, improving the indirect hepatotoxicity induced by TP.

Discovery of LH10, a novel fexaramine-based FXR agonist for the treatment of liver disease.

Farnesoid X receptor (FXR) was considered as a promising drug target in the treatment of cholestasis, drug-induced liver injury, and non-alcoholic steatohepatitis (NASH). However, the existing FXR agonists have shown different degrees of side effects in clinical trials without clear interpretation. MET-409 in clinical phase Ⅲ, has been proven significantly fewer side effects than that of other FXR agonists. This may be due to the completely different structure of FEX and other non-steroidal FXR agonists. Herein, the structure-based drug design was carried out based on FEX, and the more active FXR agonist LH10 (FEX EC50 = 0,3 µM; LH10 EC50 = 0.14 µM)) was screened out by the comprehensive SAR studies. Furthermore, LH10 exhibited robust hepatoprotective activity on the ANIT-induced cholestatic model and APAP-induced acute liver injury model, which was even better than positive control OCA. In the nonalcoholic steatohepatitis (NASH) model, LH10 significantly improved the pathological characteristics of NASH by regulating several major pathways including lipid metabolism, inflammation, oxidative stress, and fibrosis. With the above attractive results, LH10 is worthy of further evaluation as a novel agent for the treatment of liver disorders.

The role of peroxisome proliferator-activated receptors in the regulation of bile acid metabolism.

Bile acids are synthesized from cholesterol in the liver. Dysregulation of bile acid homeostasis, characterized by excessive accumulation in the liver, gallbladder and blood, can lead to hepatocellular damage and the development of cholestatic liver disease. Nuclear receptors play a crucial role in the control of bile acid metabolism by efficiently regulating bile acid synthesis and transport in the liver. Among these receptors, peroxisome proliferator-activated receptor (PPAR), a ligand-activated transcription factor belonging to the nuclear hormone receptor superfamily, controls the expression of genes involved in adipogenesis, lipid metabolism, inflammation and glucose homeostasis and has emerged as a potential therapeutic target for the treatment of the metabolic syndrome in the past two decades. Emerging evidence suggests that PPAR activation holds promise as a therapeutic target for cholestatic liver disease, as it affects both bile acid production and transport. This review provides a comprehensive overview of recent advances in elucidating the role of PPAR in the regulation of bile acid metabolism, highlighting the current position of PPAR agonists in the treatment of primary biliary cholangitis. By summarizing the specific regulatory effects of PPAR on bile acids, this review contributes to the exploration of novel therapeutic strategies for cholestatic liver diseases.

TP induces hepatic intolerance to FasL-mediated hepatocyte apoptosis by inhibiting XIAP.

Triptolide (TP) is extracted from the traditional Chinese medicine Tripterygium wilfordii Hook. F. (TWHF). Its severe toxic side effects, especially hepatotoxicity, have limited the clinical application of TP-related drugs. In this study, we investigated the mechanism of the hepatotoxic effects of TP from the perspective that TP inhibited the expression of the pro-survival protein X-linked inhibitor of apoptosis protein (XIAP) and enhanced FasL-mediated apoptosis of hepatocytes. TP and CD95/Fas antibody (Jo-2) were administered by gavage to C57BL/6 mice for 7 consecutive days. After co-administration of TP and Jo-2, mouse livers showed large areas of necrosis and apoptosis and significantly increased Caspase-3 activity. KEGG pathway enrichment analysis indicated that TP may cause the development of liver injury through the apoptotic signaling pathway. Proteinprotein interaction networks showed that XIAP played an essential role in this process. TP reduced the protein expression of XIAP after combination treatment with Jo-2/FasL in vivo/in vitro. TP and FasL co-stimulation significantly increased microRNA-137 (miR-137) levels in AML12 cells, while inhibition of miR-137 expression induced a rebound in XIAP protein expression. In conclusion, TP presensitizes hepatocytes and enhances the sensitivity of hepatocytes to the Fas/FasL pathway by inhibiting the protein expression of XIAP, leading to hepatocyte apoptosis.

Modulating intestinal barrier function by sphingosine-1-phosphate receptor 1 specific agonist SEW2871 attenuated ANIT-induced cholestatic hepatitis via the gut-liver axis.

Bile acid (BA) homeostasis throughout the enterohepatic circulation system is a guarantee of liver physiological functions. BA circulation disorders is one of the characteristic clinical manifestations of cholestasis, and have a closely relationship with intestinal barrier function, especially ileum. Here, our in vivo and in vitro studies showed that intestinal tight junctions (TJs) were disrupted by α-naphthylisothiocyanate (ANIT), which also down-regulated the protein expression of sphingosine-1-phosphate receptor 1 (S1PR1) in the top of villus of mice ileum. Activating S1PR1 by specific agonist SEW2871 could improve TJs via inhibiting ERK1/2/LKB1/AMPK signaling pathway in the ileum of ANIT-treated mice and ANIT-cultured Caco-2 cells. SEW2871 not only regained ileum TJs by activating S1PR1 in the epithelial cells of ileum mucosa, but also recovered ileum barrier function, which was further verified by the recovered BA homeostasis in mice ileum (content and tissue) by using of high-performance liquid chromatographytandem mass spectrometry (LC-MS/MS). Subsequently, the improved intestinal injury and inflammation further strengthened that SEW2871 modulated intestinal barrier function in ANIT-treated mice. Finally, our data revealed that along with the down-regulated levels of serum lipopolysaccharides (LPS), SEW2871 improved liver function and relieved hepatitis via blocking TLR4/MyD88/NF-kB signaling pathway in ANIT-treated mice. In conclusion, these results demonstrated that activating intestinal S1PR1 by SEW2871 could modulate intestinal barrier function, leading to the improvement of cholestatic hepatitis in ANIT-treated mice via the "gut-liver" axis.

Hyperoside ameliorates cisplatin-induced acute kidney injury by regulating the expression and function of Oat1.

Cisplatin is a widely used chemotherapeutic agent to treat solid tumours in clinics. However, cisplatin-induced acute kidney injury (AKI) limits its clinical application. This study investigated the effect of hyperoside (a flavonol glycoside compound) on regulating AKI.The model of cisplatin-induced AKI was established, and hyperoside was preadministered to investigate its effect on improving kidney injury.Hyperoside ameliorated renal pathological damage, reduced the accumulation of SCr, BUN, Kim-1 and indoxyl sulphate in vivo, increased the excretion of indoxyl sulphate into the urine, and upregulated the expression of renal organic anion transporter 1 (Oat1). Moreover, evaluation of rat kidney slices demonstrated that hyperoside promoted the uptake of PAH (p-aminohippurate, the Oat1 substrate), which was confirmed by transient over-expression of OAT1 in HEK-293T cells. Additionally, hyperoside upregulated the mRNA expression of Oat1 upstream regulators hepatocyte nuclear factor-1α (HNF-1α) and pregnane X receptor (PXR).These findings indicated hyperoside could protect against cisplatin-induced AKI by promoting indoxyl sulphate excretion through regulating the expression and function of Oat1, suggesting hyperoside may offer a potential tactic for cisplatin-induced AKI treatment.

K5[B3O3F4(OH)]2(NO3): the first hydroxyfluorooxoborate-nitrate with a short ultraviolet cutoff edge and large birefringence.

The first hydroxyfluorooxoborate-nitrate mixed anion compound, K5[B3O3F4(OH)]2(NO3), was synthesized by the solution evaporation method. It displays a unique structure built by K+ cations, the hydroxylated and fluorinated six-membered ring [B3O3F4(OH)] and [NO3] groups. It possesses a band gap of 5.68 eV derived from the diffuse reflectance spectrum, which corresponds to an ultraviolet cutoff edge of 218 nm. First-principles calculations show that it has a large birefringence of 0.095 at 532 nm and the result of the response electron distribution anisotropy method indicates that all three anion groups contribute positively to the birefringence, verifying the synergic contributions from the multiple anion groups.

Total glucosides of Rhizoma Smilacis Glabrae: a therapeutic approach for psoriasis by regulating Th17/Treg balance.

Total glucosides of Rhizoma Smilacis Glabrae (RSG) are selective immunosuppressants that exhibit primary efficacy in the treatment of rheumatoid arthritis through targeted inhibition of activated T cells. In this study, we aimed to investigate the potential application of RSG in the treatment of psoriasis and elucidate its mechanism of action and material basis. Our findings revealed significant improvements upon administration of RSG in an imiquimod (IMQ)-induced psoriasis model. These improvements were characterized by a remarkable increase in the number of tail scales in mice and a substantial amelioration of skin erythema, ulceration, and flaking. By transcriptome sequencing and T-cell flow sorting assay, we identified notable effects of RSG on the modulation of various cellular processes. Specifically, RSG prominently down-regulated the Th17/Treg ratio in damaged skin tissues and reduced the proportion of G2 phase cells. Furthermore, RSG exhibited a stimulatory effect on the proliferation and differentiation of epithelial cells. Of particular interest, we discovered that ß-sitosterol, sitostenone, stigmasterol, smiglanin, and cinchonain Ib displayed potent inhibitory effects on the IL-17-mediated inflammatory response in HaCaT cells. In summary, our study highlights the therapeutic potential of RSG in the treatment of psoriasis, attributed to its ability to regulate the Th17/Treg balance. These findings contribute to the development of new indications for RSG and provide a solid theoretical foundation for further exploration in this field.

Discovery of novel carboxylesterase 2 inhibitors for the treatment of delayed diarrhea and ulcerative colitis.

Human carboxylesterase 2 (hCES2) is an enzyme that metabolizes irinotecan to SN-38, a toxic metabolite considered a significant source of side effects (lethal delayed diarrhea). The hCES2 inhibitors could block the hydrolysis of irinotecan in the intestine and thus reduce the exposure of intestinal SN-38, which may alleviate irinotecan-associated diarrhea. However, existing hCES2 inhibitors (except loperamide) are not used in clinical applications due to lack of validity or acceptable safety. Therefore, developing more effective and safer drugs for treating delayed diarrhea is urgently needed. This study identified a lead compound 1 with a novel scaffold by high-throughput screening in our in-house library. After a comprehensive structure-activity relationship study, the optimal compound 24 was discovered as an efficient and highly selective hCES2 inhibitor (hCES2: IC50 = 6.72 µM; hCES1: IC50 > 100 µM). Further enzyme kinetics study indicated that compound 24 is a reversible inhibitor of hCES2 with competitive inhibition mode (Ki = 6.28 µM). The cell experiments showed that compound 24 could reduce the level of hCES2 in living cells (IC50 = 6.54 µM). The modeling study suggested that compound 24 fitted very well with the binding pocket of hCES2 by forming multiple interactions. Notably, compound 24 can effectively treat irinotecan-induced delayed diarrhea and DSS-induced ulcerative colitis, and its safety has also been verified in subtoxic studies. Based on the overall pharmacological and preliminary safety profiles, compound 24 is worthy of further evaluation as a novel agent for irinotecan-induced delayed diarrhea.

Correction: Li et al. Shikonin Attenuates Acetaminophen-Induced Hepatotoxicity by Upregulation of Nrf2 through Akt/GSK3ß Signaling. Molecules 2019, 24, 110.

The authors wish to make the following corrections to this paper [...].

Design, synthesis, and biological studies of novel sulfonamide derivatives as farnesoid X receptor agonists.

Farnesoid X receptor (FXR) is considered as a promising target for the treatment of NASH. Although many non-steroidal FXR agonists have been reported, the structure types are quite scarce and mainly limited to the isoxazole scaffold derived from GW4064. Therefore, it is crucial to expand the structure types of FXR agonist to explore wider chemical space. In this study, the structure-based scaffold hopping strategy was performed by hybrid FXR agonist 1 and T0901317, which resulted in the discovery of sulfonamide FXR agonist 19. Molecular docking study reasonably explained the SAR in this series, and compound 19 fitted well with the binding pocket in a similar mode to the co-crystal ligand. In addition, compound 19 exhibited considerable selectivity against other nuclear receptors. In NASH model, compound 19 alleviated the typical histological features of fatty liver, including steatosis, lobular inflammation, ballooning, and fibrosis. Moreover, compound 19 exhibited acceptable safety profiles with no acute toxicity to major organ. These results suggested that the novel sulfonamide FXR agonist 19 might be a promising agent for the treatment of NASH.

Design, synthesis, and biological evaluation studies of novel carboxylesterase 2 inhibitors for the treatment of irinotecan-induced delayed diarrhea.

Human carboxylesterase 2 (hCES2A), one of the most important serine hydrolases distributed in the small intestine and colon, plays a crucial role in the hydrolysis of various prodrugs and esters. Accumulating evidence has demonstrated that the inhibition of hCES2A effectively alleviate the side effects induced by some hCES2A-substrate drugs, including delayed diarrhea caused by the anticancer drug irinotecan. Nonetheless, there is a scarcity of selective and effective inhibitors that are suitable for irinotecan-induced delayed diarrhea. Following screening of the in-house library, the lead compound 01 was identified with potent inhibition on hCES2A, which was further optimized to obtain LK-44 with potent inhibitory activity (IC50 = 5.02 ± 0.67 µM) and high selectivity on hCES2A. Molecular docking and molecular dynamics simulations indicated that LK-44 can formed stable hydrogen bonds with amino acids surrounding the active cavity of hCES2A. The results of inhibition kinetics studies unveiled that LK-44 inhibited hCES2A-mediated FD hydrolysis in a mixed inhibition manner, with a Ki value of 5.28 µM. Notably, LK-44 exhibited low toxicity towards HepG2 cells according to the MTT assay. Importantly, in vivo studies showed that LK-44 significantly reduced the side effects of irinotecan-induced diarrhea. These findings suggested that LK-44 is a potent inhibitor of hCES2A with high selectivity against hCES1A, which has potential as a lead compound for the development of more effective hCES2A inhibitors to mitigate irinotecan-induced delayed diarrhea.