Dual SGLT1/SGLT2 Inhibitor Phlorizin Ameliorates Non-Alcoholic Fatty Liver Disease and Hepatic Glucose Production in Type 2 Diabetic Mice

Phlorizin, an Important Glucoside: Research Progress on Its Biological Activity and Mechanism

Phlorizin, as a flavonoid from a wide range of sources, is gradually becoming known for its biological activity. Phlorizin can exert antioxidant effects by regulating the IL-1β/IKB-α/NF-KB signaling pathway. At the same time, it exerts its antibacterial activity by reducing intracellular DNA agglutination, reducing intracellular protein and energy synthesis, and destroying intracellular metabolism. In addition, phlorizin also has various pharmacological effects such as antiviral, antidiabetic, antitumor, and hepatoprotective effects. Based on domestic and foreign research reports, this article reviews the plant sources, extraction, and biological activities of phlorizin, providing a reference for improving the clinical application of phlorizin.

Reduced mortality and morbidity associated with metformin and SGLT2 inhibitor therapy in patients with type 2 diabetes mellitus and cirrhosis

INTRODUCTION

Evidence for dual antidiabetic therapy in type 2 diabetes mellitus patients with cirrhosis is limited. This study compared 5-year mortality, composite hepatic decompensation risk, and hepatocellular carcinoma occurrence in patients with diabetes and cirrhosis who were either on metformin monotherapy or on dual metformin and sodium-glucose co-transporter-2 inhibitor (SGLT2-I) therapy.

METHODS

This retrospective study used the TriNetX Research Network to identify propensity score-matched patients treated with either metformin or dual metformin and SGLT2-I therapy. Our outcomes were all-cause mortality, a composite of hepatic decompensation events, and hepatocellular carcinoma (HCC) occurrence over 5 years. We estimated hazard ratios within each cohort with 95% confidence intervals (CI) and Kaplan-Meier estimates for time-to-event distributions with Log-rank tests. We were able to stratify our cohorts by age, sex, race, and ethnicity. We further investigated a subset of diabetic patients with cirrhosis due to MASH.

RESULTS

In our propensity score-matched cohorts of type 2 diabetes patients with cirrhosis, those on dual metformin and SGLT2-I therapy had decreased risk for mortality (HR 0.57, 95%CI 0.41-0.81), reduced composite risk of becoming decompensated (HR 0.63, 95%CI 0.43-0.93) and less than half the risk for developing HCC (HR 0.43, 95%CI 0.21-0.88) compared to those on mono metformin therapy. We did not find a difference between mono or dual therapy treatment for mortality, decompensation, or HCC risks in the subset of patients with MASH cirrhosis.

CONCLUSION

Dual metformin and SGLT2-I treatment in type 2 diabetes patients with cirrhosis are associated with improved mortality and hepatic complications.

Natural products in pursuing novel therapies of nonalcoholic fatty liver disease and steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) are hepatic manifestations of systemic metabolic dysfunction, which affect one-quarter of the adult population worldwide as estimated, and exhibit high risk in progressing to hepatic fibrosis, cirrhosis, and hepatocellular carcinoma. Current drug discovery focuses on modifying homeostasis of lipids, carbohydrates, and cholesterol, as well as inhibiting inflammation and fibrogenesis. Many natural products show promising activities on various molecular targets involving these mechanisms; however, they have not been fully exploited. Since some compounds are components of healthy food, they may be employed in chemoprevention as adjuvants to lifestyle modification, while natural products such as alkaloids and sesquiterpenoids could serve as promising starting points for structural modifications and deserve further development.

Simultaneous SGLT2 inhibition and caloric restriction improves insulin resistance and kidney function in OLETF rats

SGLT2 inhibitors (SGLT2i) are emerging as a novel therapy for type 2 diabetes due to their effective hypoglycemic and potential cardio- and nephroprotective effects, while caloric restriction (CR) is a common behavioral modification to improve adiposity and insulin resistance. Therefore, both interventions simultaneously may potentially further improve metabolic syndrome by enhancing carbohydrate metabolism. To test this hypothesis, cohorts of 10-week old, male Long Evans Tokushima Otsuka (LETO) and Otsuka Long Evans Tokushima Fatty (OLETF) rats were treated with SGLT2i (10 mg luseoglifozin/kg/day x 4 wks) (OLETF only) and/or 30% CR (2 wks at 12 weeks of age). CR maintained body mass in both strains while SGLT2i alone did not have any effect on body mass. Simultaneous treatments decreased SBP in OLETF vs SGLT2i alone, decreased insulin resistance index (IRI), and increased creatinine clearance vs OLETF ad lib. Conversely, CR decreased albuminuria independent of SGLT2i. In conclusion, SGLT2i treatment by itself did not elicit significant improvements in insulin resistance, kidney function or blood pressure. However, when combined with CR, these changes where more profound than with CR alone without inducing chronic hypoglycemia.

Hepatoprotective effects of Phloridzin against isoniazid-rifampicin induced liver injury by regulating CYP450 and Nrf2/HO-1 pathway in mice

The protective effect of phloridzin (PHL) and its potential mechanism were examined in mice with liver injury induced by isoniazid (INH) and rifampicin (RFP). The mice were randomly divided into normal control group, model group, low (80 mg/kg), medium (160 mg/kg) and high (320 mg/kg) phloridzin-treated groups. After 28 days treatment, blood and liver tissue were collected and analysed. The results revealed that PHL regulated liver function related indicators and reduced the pathological tissue damage, indicating that PHL significantly alleviated the liver injury. Furthermore, the level of cytochrome P450 (CYP450) enzyme, the expression of cytochrome P450 3A4 (CYP3A4), cytochrome P450 2E1 (CYP2E1), heme oxygenase-1 (HO-1) and nuclear factor erythroid 2-related factor 2 (Nrf2) mRNA and protein were inhibited by PHL. These results indicated that PHL exerts a protecting effect against liver injury induced by combination of RFP and INH. The potential mechanisms may be concerned with the activation of Nrf2/HO-1 signaling pathway containing its key antioxidant enzymes and regulation of CYP3A4 and CYP2E1.

Role of Sodium-Glucose Co-Transporter 2 Inhibitors in the Regulation of Inflammatory Processes in Animal Models

Sodium-glucose co-transporter 2 inhibitors, also known as gliflozins, were developed as a novel class of anti-diabetic agents that promote glycosuria through the prevention of glucose reabsorption in the proximal tubule by sodium-glucose co-transporter 2. Beyond the regulation of glucose homeostasis, they resulted as being effective in different clinical trials in patients with heart failure, showing a strong cardio-renal protective effect in diabetic, but also in non-diabetic patients, which highlights the possible existence of other mechanisms through which gliflozins could be exerting their action. So far, different gliflozins have been approved for their therapeutic use in T2DM, heart failure, and diabetic kidney disease in different countries, all of them being diseases that have in common a deregulation of the inflammatory process associated with the pathology, which perpetuates and worsens the disease. This inflammatory deregulation has been observed in many other diseases, which led the scientific community to have a growing interest in the understanding of the biological processes that lead to or control inflammation deregulation in order to be able to identify potential therapeutic targets that could revert this situation and contribute to the amelioration of the disease. In this line, recent studies showed that gliflozins also act as an anti-inflammatory drug, and have been proposed as a useful strategy to treat other diseases linked to inflammation in addition to cardio-renal diseases, such as diabetes, obesity, atherosclerosis, or non-alcoholic fatty liver disease. In this work, we will review recent studies regarding the role of the main sodium-glucose co-transporter 2 inhibitors in the control of inflammation.

Identification of Drug Transporter Genomic Variants and Inhibitors That Protect Against Doxorubicin-Induced Cardiotoxicity

BACKGROUND

Multiple pharmacogenomic studies have identified the synonymous genomic variant rs7853758 (G > A, L461L) and the intronic variant rs885004 in SLC28A3 (solute carrier family 28 member 3) as statistically associated with a lower incidence of anthracycline-induced cardiotoxicity. However, the true causal variant(s), the cardioprotective mechanism of this locus, the role of SLC28A3 and other solute carrier (SLC) transporters in anthracycline-induced cardiotoxicity, and the suitability of SLC transporters as targets for cardioprotective drugs has not been investigated.

METHODS

Six well-phenotyped, doxorubicin-treated pediatric patients from the original association study cohort were recruited again, and human induced pluripotent stem cell-derived cardiomyocytes were generated. Patient-specific doxorubicin-induced cardiotoxicity (DIC) was then characterized using assays of cell viability, activated caspase 3/7, and doxorubicin uptake. The role of SLC28A3 in DIC was then queried using overexpression and knockout of SLC28A3 in isogenic human-induced pluripotent stem cell-derived cardiomyocytes using a CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated protein 9). Fine-mapping of the SLC28A3 locus was then completed after SLC28A3 resequencing and an extended in silico haplotype and functional analysis. Genome editing of the potential causal variant was done using cytosine base editor. SLC28A3-AS1 overexpression was done using a lentiviral plasmid-based transduction and was validated using stranded RNA-sequencing after ribosomal RNA depletion. Drug screening was done using the Prestwick Chemical Library (n = 1200), followed by in vivo validation in mice. The effect of desipramine on doxorubicin cytotoxicity was also investigated in 8 cancer cell lines.

RESULTS

Here, using the most commonly used anthracycline, doxorubicin, we demonstrate that patient-derived cardiomyocytes recapitulate the cardioprotective effect of the SLC28A3 locus and that SLC28A3 expression influences the severity of DIC. Using Nanopore-based fine-mapping and base editing, we identify a novel cardioprotective single nucleotide polymorphism, rs11140490, in the SLC28A3 locus; its effect is exerted via regulation of an antisense long noncoding RNA (SLC28A3-AS1) that overlaps with SLC28A3. Using high-throughput drug screening in patient-derived cardiomyocytes and whole organism validation in mice, we identify the SLC competitive inhibitor desipramine as protective against DIC.

CONCLUSIONS

This work demonstrates the power of the human induced pluripotent stem cell model to take a single nucleotide polymorphism from a statistical association through to drug discovery, providing human cell-tested data for clinical trials to attenuate DIC.

Effect of Codonopsis Radix and Polygonati Rhizoma on the regulation of the IRS1/PI3K/AKT signaling pathway in type 2 diabetic mice

OBJECTIVE

Codonopsis Radix and Polygonati Rhizoma (CRPR) has a good hypoglycemic effect. The aims of the present study were to investigate the effect of CRPR on high-fat/high-sugar diet (HFHSD)- and streptozotocin (STZ)-induced type 2 diabetes mellitus (T2DM) mice as well as to investigate the involved mechanism.

METHODS

A T2DM mouse model was generated by combining HFHSD and STZ. After the model was established, normal and model groups received the same volume of normal saline intragastrically, and the negative control group was treated with metformin (200 mg/kg·BW). The low, medium, and high CRPR groups received four consecutive weeks of oral gavage with CRPR doses of 2.5, 5, and 10 g/kg·BW, respectively, during the course of the study. Body weight and fasting blood glucose (FBG) were measured on a weekly basis. Enzyme-linked immunosorbent assay (ELISAs) were used to evaluate the serum and liver samples. Hematoxylin and eosin (H&E) staining was utilized to observe the pathological status of the liver and pancreas. Western blot (WB) analysis was performed to evaluate the protein expression levels of PI3K, p-PI3K, AKT, and p-AKT.

RESULTS

Compared to model mice, each treatment group had significantly elevated levels of FBG, total cholesterol (TC), and triacylglycerol (TG) (P<0.01 and P<0.05, respectively). The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were significantly reduced in the treatment groups compared to the model group (P<0.01). Compared to the model group, fasting insulin (FINS) levels were elevated in all groups of CRPR (P<0.05), and there were significantly higher levels of high-density lipoprotein cholesterol (HDL-C) in both the low-dose and high-dose CRPR groups (P<0.05). H&E staining indicated that CRPR treatment reduced organ enlargement, improved liver lipid accumulation, and repaired islet injury in T2DM mice. Moreover, WB analysis demonstrated that all CRPR groups significantly upregulated the protein expression of IRS1, p-GSK3β, PI3K, p-Akt and p-FOXO1(P<0.05) as well as significantly downregulated p-IRS1 and FOXO1 protein expression (P<0.05).

CONCLUSION

The present study demonstrated that CRPR effectively improves the metabolic disturbance of lipids, repairs damaged liver tissues, repairs damaged pancreatic tissues, and reduces insulin resistance (IR) in T2DM mice. The mechanism of action may be associated with upregulation of the IRS1/PI3K/AKT signaling pathway and inhibition of IRS1 phosphorylation.

AGEs-Induced and Endoplasmic Reticulum Stress/Inflammation-Mediated Regulation of GLUT4 Expression and Atherogenesis in Diabetes Mellitus

In recent decades, complex and exquisite pathways involved in the endoplasmic reticulum (ER) and inflammatory stress responses have been demonstrated to participate in the development and progression of numerous diseases, among them diabetes mellitus (DM). In those pathways, several players participate in both, reflecting a complicated interplay between ER and inflammatory stress. In DM, ER and inflammatory stress are involved in both the pathogenesis of the loss of glycemic control and the development of degenerative complications. Furthermore, hyperglycemia increases the generation of advanced glycation end products (AGEs), which in turn refeed ER and inflammatory stress, contributing to worsening glycemic homeostasis and to accelerating the development of DM complications. In this review, we present the current knowledge regarding AGEs-induced and ER/inflammation-mediated regulation of the expression of GLUT4 (solute carrier family 2, facilitated glucose transporter member 4), as a marker of glycemic homeostasis and of cardiovascular disease (CVD) development/progression, as a leading cause of morbidity and mortality in DM.

Effects of phloridzin on blood glucose and key enzyme G-6-Pase of gluconeogenesis in mice

The effects of phloridzin (PHL), main component of Malus hupehensis (MH) tea leaves, on blood glucose (BG) and glucose-6-phosphatase (G-6-Pase) were investigated to provide a basis for finding a scheme of stabilizing BG. Glucose uptake of insulin resistant HepG2 cells was measured by glucose oxidase method. Glucose tolerance, fasting BG (FBG) and postprandial BG (PBG) were determined by BG test strips. The expression of G-6-Pase was detected by Western blot. The results showed that glucose uptake was enhanced and the expression of G-6-Pase was inhibited by PHL in insulin resistant HepG2 cells. Glucose tolerance was enhanced, FBG level was increased and PBG level was decreased by PHL in mice. The expression of G-6-Pase in the liver was enhanced under fasting state, and was inhibited by the low and medium dose under postprandial state. It indicated that PHL has a positive effect on stabilizing BG in mice, which is related to bidirectional regulation of G-6-Pase activity. PRACTICAL APPLICATIONS: Malus hupehensis, edible and medicinal plant, which has been proved by long-term application and experiments that it has a good effect on stabilizing blood glucose, preventing diabetes and adjuvant treatment. Its effect is closely related to its main component PHL. Thus, MH can be used as a dietary regulating drink for daily life to maintain blood glucose. Its main ingredient is PHL, which can be developed as a candidate drug for diabetes treatment.

Phloridzin Ameliorates Lipid Deposition in High-Fat-Diet-Fed Mice with Nonalcoholic Fatty Liver Disease via Inhibiting the mTORC1/SREBP-1c Pathway

We aimed to investigate whether phloridzin could alleviate nonalcoholic fatty liver disease (NAFLD) in mice, which was induced by feeding a high-fat diet (HFD). We initially analyzed the effect of phloridzin on alleviating HFD-induced NAFLD in C57BL/6J mice and oleic acid (OA)-stimulated human normal liver L-02 cells (L02). Then, we investigated the mechanism of phloridzin on the mTORC1/sterol-regulatory element-binding protein-1c (SREBP-1c) signaling pathway by siRNA analysis, qRT-PCR, flow cytometry, and western blot analysis in vivo and in vitro. The results revealed that phloridzin significantly inhibited the increase in body weight, alleviated abnormal lipid metabolism, and decreased lipid biosynthesis and insulin resistance. Moreover, phloridzin augmented the number of CD8⁺CD122⁺PD-1⁺ Tregs and CD4⁺FoxP3⁺ Tregs in HFD-fed C57BL/6J mice and HFD-fed aP2-SREBF1c mice and downregulated the mTORC1/SREBP-1c signaling pathway-related protein expressions in vivo and in vitro. Furthermore, phloridzin reduced the expression of SREBP-1c in SREBP-1c-RNAi-lentivirus-transfected L02 cells and reversed the SREBP-1c expression in HFD-fed aP2-SREBF1c transgenic mice. Phloridzin ameliorates lipid accumulation and insulin resistance via inhibiting the mTORC1/SREBP-1c pathways. These results indicated that phloridzin may actively ameliorate NAFLD.

The Bioavailability, Extraction, Biosynthesis and Distribution of Natural Dihydrochalcone: Phloridzin

Phloridzin is an important phytochemical which was first isolated from the bark of apple trees. It is a member of the dihydrochalcones and mainly distributed in the plants of the Malus genus, therefore, the extraction method of phloridzin was similar to those of other phenolic substances. High-speed countercurrent chromatography (HSCCC), resin adsorption technology and preparative high-performance liquid chromatography (HPLC) were used to separate and purify phloridzin. Many studies showed that phloridzin had multiple pharmacological effects, such as antidiabetic, anti-inflammatory, antihyperglycaemic, anticancer and antibacterial activities. Besides, the physiological activities of phloridzin are cardioprotective, neuroprotective, hepatoprotective, immunomodulatory, antiobesity, antioxidant and so on. The present review summarizes the biosynthesis, distribution, extraction and bioavailability of the natural compound phloridzin and discusses its applications in food and medicine.

Empagliflozin Attenuates Non-Alcoholic Fatty Liver Disease (NAFLD) in High Fat Diet Fed ApoE(-/-) Mice by Activating Autophagy and Reducing ER Stress and Apoptosis

AIMS/HYPOTHESIS

SGLT-2 inhibitors (SGLT-2i) have been studied as potential treatments against NAFLD, showing varying beneficial effects. The molecular mechanisms mediating these effects have not been fully clarified. Herein, we investigated the impact of empagliflozin on NAFLD, focusing particularly on ER stress, autophagy and apoptosis.

METHODS

Five-week old ApoE^(-/-) mice were switched from normal to a high-fat diet (HFD). After five weeks, mice were randomly allocated into a control group (HFD + vehicle) and Empa group (HFD + empagliflozin 10 mg/kg/day) for five weeks. At the end of treatment, histomorphometric analysis was performed in liver, mRNA levels of Fasn, Screbp-1, Scd-1, Ppar-γ, Pck-1, Mcp-1, Tnf-α, Il-6, F4/80, Atf4, Elf2α, Chop, Grp78, Grp94, Χbp1, Ire1α, Atf6, mTor, Lc3b, Beclin-1, P62, Bcl-2 and Bax were measured by qRT-PCR, and protein levels of p-EIF2α, EIF2a, CHOP, LC3II, P62, BECLIN-1 and cleaved CASPASE-8 were assessed by immunoblotting.

RESULTS

Empagliflozin-treated mice exhibited reduced fasting glucose, total cholesterol and triglyceride serum levels, as well as decreased NAFLD activity score, decreased expression of lipogenic enzymes (Fasn, Screbp-1c and Pck-1) and inflammatory molecules (Mcp-1 and F4/80), compared to the Control group. Empagliflozin significantly decreased the expression of ER stress molecules Grp78, Ire1α, Xbp1, Elf2α, Atf4, Atf6, Chop, P62(Sqstm1) and Grp94; whilst activating autophagy via increased AMPK phosphorylation, decreased mTOR and increased LC3B expression. Finally, empagliflozin increased the Bcl2/Bax ratio and inhibited CASPASE-8 cleavage, reducing liver cell apoptosis. Immunoblotting analysis confirmed the qPCR results.

CONCLUSION

These novel findings indicate that empagliflozin treatment for five weeks attenuates NAFLD progression in ApoE^(-/-) mice by promoting autophagy, reducing ER stress and inhibiting hepatic apoptosis.

Empagliflozin Attenuates Non-Alcoholic Fatty Liver Disease (NAFLD) in High Fat Diet Fed ApoE(-/-) Mice by Activating Autophagy and Reducing ER Stress and Apoptosis

AIMS/HYPOTHESIS

SGLT-2 inhibitors (SGLT-2i) have been studied as potential treatments against NAFLD, showing varying beneficial effects. The molecular mechanisms mediating these effects have not been fully clarified. Herein, we investigated the impact of empagliflozin on NAFLD, focusing particularly on ER stress, autophagy and apoptosis.

METHODS

Five-week old ApoE(-/-) mice were switched from normal to a high-fat diet (HFD). After five weeks, mice were randomly allocated into a control group (HFD + vehicle) and Empa group (HFD + empagliflozin 10 mg/kg/day) for five weeks. At the end of treatment, histomorphometric analysis was performed in liver, mRNA levels of Fasn, Screbp-1, Scd-1, Ppar-γ, Pck-1, Mcp-1, Tnf-α, Il-6, F4/80, Atf4, Elf2α, Chop, Grp78, Grp94, Χbp1, Ire1α, Atf6, mTor, Lc3b, Beclin-1, P62, Bcl-2 and Bax were measured by qRT-PCR, and protein levels of p-EIF2α, EIF2a, CHOP, LC3II, P62, BECLIN-1 and cleaved CASPASE-8 were assessed by immunoblotting.

RESULTS

Empagliflozin-treated mice exhibited reduced fasting glucose, total cholesterol and triglyceride serum levels, as well as decreased NAFLD activity score, decreased expression of lipogenic enzymes (Fasn, Screbp-1c and Pck-1) and inflammatory molecules (Mcp-1 and F4/80), compared to the Control group. Empagliflozin significantly decreased the expression of ER stress molecules Grp78, Ire1α, Xbp1, Elf2α, Atf4, Atf6, Chop, P62(Sqstm1) and Grp94; whilst activating autophagy via increased AMPK phosphorylation, decreased mTOR and increased LC3B expression. Finally, empagliflozin increased the Bcl2/Bax ratio and inhibited CASPASE-8 cleavage, reducing liver cell apoptosis. Immunoblotting analysis confirmed the qPCR results.

CONCLUSION

These novel findings indicate that empagliflozin treatment for five weeks attenuates NAFLD progression in ApoE(-/-) mice by promoting autophagy, reducing ER stress and inhibiting hepatic apoptosis.

The Association between Hepatic Encephalopathy and Diabetic Encephalopathy: The Brain-Liver Axis

Hepatic encephalopathy (HE) is one of the main consequences of liver disease and is observed in severe liver failure and cirrhosis. Recent studies have provided significant evidence that HE shows several neurological symptoms including depressive mood, cognitive dysfunction, impaired circadian rhythm, and attention deficits as well as motor disturbance. Liver disease is also a risk factor for the development of diabetes mellitus. Diabetic encephalopathy (DE) is characterized by cognitive dysfunction and motor impairment. Recent research investigated the relationship between metabolic changes and the pathogenesis of neurological disease, indicating the importance between metabolic organs and the brain. Given that a diverse number of metabolites and changes in the brain contribute to neurologic dysfunction, HE and DE are emerging types of neurologic disease. Here, we review significant evidence of the association between HE and DE, and summarise the common risk factors. This review may provide promising therapeutic information and help to design a future metabolic organ-related study in relation to HE and DE.

Regioselective Hydroxylation of Phloretin, a Bioactive Compound from Apples, by Human Cytochrome P450 Enzymes

Phloretin, the major polyphenol compound in apples and apple products, is interesting because it shows beneficial effects on human health. It is mainly found as a form of glucoside, phlorizin. However, the metabolic pathway of phloretin in humans has not been reported. Therefore, identifying phloretin metabolites made in human liver microsomes and the human cytochrome P450 (P450) enzymes to make them is interesting. In this study, the roles of human liver P450s for phloretin oxidation were examined using human liver microsomes and recombinant human liver P450s. One major metabolite of phloretin in human liver microsomes was 3-OH phloretin, which is the same product of a bacterial CYP102A1-catalyzed reaction of phloretin. CYP3A4 and CYP2C19 showed k_cat values of 3.1 and 5.8 min^-1, respectively. However, CYP3A4 has a 3.3-fold lower K_m value than CYP2C19. The catalytic efficiency of a CYP3A4-catalyzed reaction is 1.8-fold higher than a reaction catalyzed by CYP2C19. Whole-cell biotransformation with CYP3A4 was achieved 0.16 mM h^-1 productivity for 3-OH phlorein from 8 mM phloretin at optimal condition. Phloretin was a potent inhibitor of CYP3A4-catalyzed testosterone 6β-hydroxylation activity. Antibodies against CYP3A4 inhibited up to 90% of the microsomal activity of phloretin 3-hydroxylation. The immunoinhibition effect of anti-2C19 is much lower than that of anti-CYP3A4. Thus, CYP3A4 majorly contributes to the human liver microsomal phloretin 3-hydroxylation, and CYP2C19 has a minor role.