Phloretin induces G2/M arrest and apoptosis by suppressing the ß-catenin signaling pathway in colorectal carcinoma cells.

Colorectal carcinoma (CRC) is the third most prevalent cancer, causing a significant mortality worldwide. Present available therapies are surgery, chemotherapy including radiotherapy, and these are known to be associated with heavy side effects. Therefore, nutritional intervention in the form of natural polyphenols has been well recognised to prevent CRC. Phloretin, a known dihydrochalcone is present in apple, pear and strawberry. This has been proven to induce apoptosis in cancer cells and also exhibited anti-inflammatory activity, thus can be explored as a potential anticancer nutraceutical agent. This study demonstrated phloretin's significant in vitro anticancer activity against CRC. Phloretin suppressed cell proliferation, colony forming ability and cellular migration in human colorectal cancer HCT-116 and SW-480 cells. Results also revealed that phloretin generated reactive oxygen species (ROS) which provoked depolarization of mitochondrial membrane potential (MMP) and further contributed to cytotoxicity in colon cancer cells. Phloretin also modulated the cell cycle regulators including cyclins and cyclin-dependent kinases (CDKs) and halted cell cycle at G2/M phase. Moreover, it also induced apoptosis by regulating the expression of Bax and BCl-2. The Wnt/ß-catenin signaling is inactivated by phloretin by targeting the downstream oncogenes namely CyclinD1, c-Myc and Survivin which are involved in the proliferation and apoptosis of colon cancer cells. In our study we showed that lithium chloride (LiCl) induced the expression of ß-catenin and its target genes and the co-treatment of phloretin circumvent its effect and downregulated the Wnt/ß-catenin signaling. In conclusion, our results strongly suggested that phloretin can be utilized as a nutraceutical anticancer agent for combating CRC.

Phloretin ameliorates diabetes-induced endothelial injury through AMPK-dependent anti-EndMT pathway.

Diabetic cardiovascular complications contribute more than half of diabetes mortality. Endothelial damage and subsequent pathological changes play a key role in this process. Phloretin, a plant-derived dihydrochalcone compound, was reported to have the activities in regulating metabolism homeostasis and anti-inflammation. However, its effects and the mechanism on early stage endothelial injury caused by diabetes are not clear yet. In our present study, human umbilical vein endothelial cells (HUVECs) were stimulated by high glucose or advanced glycation end products (AGEs) to induce endothelial damage, and streptozotocin (STZ) -induced diabetes mouse model was used for in vivo study. Our results showed that phloretin effectively reduced endothelial damage marker monocyte chemotactic protein-1 (MCP1) as well as pro-calcification factors bone morphogenetic protein-2 (BMP2) and receptor activator of NF-κB ligand (RANKL) expression, reversed the increased vimentin and decreased CD31 dose-dependently in vitro and in vivo. Phloretin had no effect on blood glucose level. However, it ameliorated endothelial injury and vascular fibrosis in diabetic mice. Further experiments revealed that phloretin could enhance AMP activated protein kinase (AMPK) activation and upregulate peroxidase proliferator activated receptor-gamma coactivator-lα (PGC1α) level, and inhibit the activation of TGFß-Smad2-Snail signalling pathway which was abrogated by AMPK inhibitor, providing a rational mechanism that AMPK activation was required for the effects of phloretin on endothelial injury and endothelial-mesenchymal transformation (EndMT). Our data reveal a new role of phloretin in protection of diabetic endothelial damage via AMPK-dependent anti-EndMT activation, and also provide a potential therapeutic way for diabetic endothelial damage and its subsequent cardiovascular complications.

Phloretin suppresses neuroinflammation by autophagy-mediated Nrf2 activation in macrophages.

BACKGROUND: Macrophages play a dual role in neuroinflammatory disorders such as multiple sclerosis (MS). They are involved in lesion onset and progression but can also promote the resolution of inflammation and repair of damaged tissue. In this study, we investigate if and how phloretin, a flavonoid abundantly present in apples and strawberries, lowers the inflammatory phenotype of macrophages and suppresses neuroinflammation. METHODS: Transcriptional changes in mouse bone marrow-derived macrophages upon phloretin exposure were assessed by bulk RNA sequencing. Underlying pathways related to inflammation, oxidative stress response and autophagy were validated by quantitative PCR, fluorescent and absorbance assays, nuclear factor erythroid 2-related factor 2 (Nrf2) knockout mice, western blot, and immunofluorescence. The experimental autoimmune encephalomyelitis (EAE) model was used to study the impact of phloretin on neuroinflammation in vivo and confirm underlying mechanisms. RESULTS: We show that phloretin reduces the inflammatory phenotype of macrophages and markedly suppresses neuroinflammation in EAE. Phloretin mediates its effect by activating the Nrf2 signaling pathway. Nrf2 activation was attributed to 5' AMP-activated protein kinase (AMPK)-dependent activation of autophagy and subsequent kelch-like ECH-associated protein 1 (Keap1) degradation. CONCLUSIONS: This study opens future perspectives for phloretin as a therapeutic strategy for neuroinflammatory disorders such as MS. TRIAL REGISTRATION: Not applicable.

Phloretin ameliorates dextran sulfate sodium-induced ulcerative colitis in mice by regulating the gut microbiota.

Phloretin, extracted from the pericarp and velamen of apples or pears, is a dihydrochalcone flavonoid with anti-bacterial and anti-inflammatory activities. It has been reported that phloretin has anti-inflammatory effects in ulcerative colitis (UC) mice. However, the role of the gut microbiota in the phloretin anti-UC process remains unclear. In this study, we observed that the anti-UC effect of phloretin was affected by co-housing, probably because of the transmissible nature of the gut micobiota. Through fecal micobiota transplantation (FMT), the effects of the gut microbiota on the anti-UC of phloretin were further confirmed. UC was induced in mice by administrating 3% dextran sulfate sodium (DSS) in drinking water for 7 days. Phloretin (60 mg/kg) was administered by gavage every day during the experiment. Fecal microbes (109 CFU/mL) from phloretin-treated UC mice were administered by gavage to non-phloretin-treated UC mice for 7 days. The results showed that FMT, like phloretin, ameliorated UC by improving disease symptoms and colon inflammation, balancing inflammatory cytokines, maintaining intestinal barrier integrity, restoring systemic immune function, inhibiting NF-κB and NLRP3 inflammasome activation and ameliorating the oxidant stress. Both FMT and phloretin treatment increased the levels of Bacteroidetes, Alistipes and Lactobacillus and decreased those of Firmicutes, Oscillibacter and Ruminiclostridium_6. Correlation analysis between gut microbes and micro-environmental factors revealed that Alistipes abundance was negatively correlated with DAI, pathological score, and TNF-α, IL-6 and IL-1ß levels, and Alistipes was more abundant in phloretin or FMT treated UC mice. Oscillibacter abundance was significantly positively correlated with IL-6 and IL-1ß levels and pathological score, and Oscillibacter was increased in UC mice. Furthermore, network analysis of the dominant genera revealed that Alistipes abundance was negatively related to Oscillibacter abundance. In conclusion, this study suggests that the anti-UC effects of phloretin are achieved through regulation of the gut microbiota and phloretin has the potential to be developed as a promising agent for the treatment of UC.

Glucose Transporter 1-Dependent Glycolysis Is Increased during Aging-Related Lung Fibrosis, and Phloretin Inhibits Lung Fibrosis.

Aging is associated with metabolic diseases such as type 2 diabetes mellitus, cardiovascular disease, cancer, and neurodegeneration. Aging contributes to common processes including metabolic dysfunction, DNA damage, and reactive oxygen species generation. Although glycolysis has been linked to cell growth and proliferation, the mechanisms by which the activation of glycolysis by aging regulates fibrogenesis in the lung remain unclear. The objective of this study was to determine if glucose transporter 1 (GLUT1)-induced glycolysis regulates age-dependent fibrogenesis of the lung. Mouse and human lung tissues were analyzed for GLUT1 and glycolytic markers using immunoblotting. Glycolytic function was measured using a Seahorse apparatus. To study the effect of GLUT1, genetic inhibition of GLUT1 was performed by short hairpin RNA transduction, and phloretin was used for pharmacologic inhibition of GLUT1. GLUT1-dependent glycolysis is activated in aged lung. Genetic and pharmacologic inhibition of GLUT1 suppressed the protein expression of α-smooth muscle actin, a key cytoskeletal component of activated fibroblasts, in mouse primary lung fibroblast cells. Moreover, we demonstrated that the activation of AMP-activated protein kinase, which is regulated by GLUT1-dependent glycolysis, represents a critical metabolic pathway for fibroblast activation. Furthermore, we demonstrated that phloretin, a potent inhibitor of GLUT1, significantly inhibited bleomycin-induced lung fibrosis in vivo. These results suggest that GLUT1-dependent glycolysis regulates fibrogenesis in aged lung and that inhibition of GLUT1 provides a potential target of therapy of age-related lung fibrosis.

Evaluation of anti-acne properties of phloretin in vitro and in vivo.

OBJECTIVE: This study aimed to investigate the anti-acne properties of phloretin in vitro and in vivo. METHODS: Anti-microbial activity against Propionibacterium acnes (P. acnes), Propionibacterium granulosum (P. granulosum) and Staphylococcus epidermidis (S. epidermidis) were observed by the minimum inhibitory concentration (MIC) and disc diffusion methods. The anti-inflammatory effects were studied in HaCaT cells based on P. acnes-induced inflammatory mediators, including PGE2 and COX-2, examined through enzyme-linked immunosorbent assay (ELISA) and luciferase reporter gene assay. Thirty healthy subjects with whiteheads participated in the clinical study. Comedo counting, and the amount of sebum and porphyrin were measured before treatment and following 4 consecutive weeks of treatment with phloretin. RESULTS: Phloretin showed anti-microbial activities against P. acnes, P. granulosum, S. epidermidis with the MIC of 0.5, 0.5 and 0.25 mg mL(-1) , respectively. P. acnes-induced activation of the COX-2 promoter was markedly attenuated by phloretin treatment. Consistent with these results, inhibition of PGE2 production was also observed. In 1-month, placebo-controlled trials, phloretin showed clinically and statistically significant reduction of comedo counts and sebum output level. Compared to before treatment, whiteheads, blackheads, papules, sebum output level and amount of sebum and porphyrin were significantly decreased at 4 weeks in the test group. CONCLUSIONS: This study revealed that phloretin inhibits the growth of P. acnes, P. granulosum, and S. epidermidis. In addition, we demonstrated that phloretin attenuates COX-2 and PGE2 expression during the P. acnes-induced upregulation of inflammatory signalling. Clinical studies further suggested that treatment with formulations containing phloretin confers anti-acne benefits. Based on these results, we suggest that phloretin may be introduced as a possible acne-mitigating agent.

Phloretin: a comprehensive review of its potential against diabetes and associated complications.

OBJECTIVES: Phloretin is ubiquitous in apples (Malus domestica) and other fruits and has potential antidiabetic properties. Considering the preclinical potential of phloretin, its transition to clinical observations has unintentionally been neglected, particularly within the diabetic population. Furthermore, a comprehensive understanding of its pharmacokinetics remains elusive. This review seeks to offer valuable insights into phloretin's physical properties, pharmacokinetics, and pharmacodynamics, aiming to unveil opportunities for additional research on its therapeutic potential in the context of diabetes. KEY FINDINGS: All pharmacokinetic reports of phloretin confirm that the utilization of phloretin gets enhanced during diabetic conditions. Phloretin targets pathomechanisms such as glucose transporter 4 (GLUT4) and peroxisome proliferator's activity-activated receptor-γ (PPAR-γ) to decrease insulin resistance in diabetic conditions. Moreover, phloretin targets inflammatory, oxidative, and apoptotic signaling to minimize the progression of diabetes-associated macro- and microvascular complications. SUMMARY: The pleiotropic antidiabetic action of phloretin is mainly dependent on its pharmacokinetics. Nevertheless, further investigation into the altered pharmacokinetics of phloretin during diabetic conditions is essential. Additionally, the results derived from clinical studies utilized apples, apple extract, and supplements containing phloretin. Greater emphasis should be placed on future clinical studies to assess the potential of phloretin as a standalone compound.

Natural compound phloretin restores periodontal immune homeostasis via HIF-1α-regulated PI3K/Akt and glycolysis in macrophages.

Periodontitis is a chronic inflammatory disease that affects about 45 %-50 % of adults worldwide, but the efficacy of current clinical therapies is unsatisfactory due to the complicated periodontal immune microenvironment. Thus, developing drugs that can regulate innate immune cells (e.g., macrophages) is a potent strategy to treat periodontitis. Here, we report that phloretin, a food plant-derived natural compound, is sufficient to alleviate periodontitis through immune regulation. In vivo, phloretin treatment could significantly reduce alveolar bone resorption and periodontal inflammation in mouse periodontitis models. In vitro, phloretin could suppress proinflammatory (M1-like) polarization and cytokine release in macrophages induced by LPS. Mechanistically, the immune regulatory role of phloretin in macrophages may be due to its metabolic regulation effect. Phloretin might restore the balance of M1/M2 macrophage transition in periodontitis by inhibiting HIF-1α-mediated glycolysis and PI3k/Akt pathways, thereby reducing the proinflammatory effect and immune disorder caused by over-activated M1 macrophages. Together, this study highlights that natural compound, such as phloretin, can restore periodontal immune homeostasis by metabolic regulation of macrophages, which may provide novel insight into the treatment of periodontitis.

Amorphous solid dispersion augments the bioavailability of phloretin and its therapeutic efficacy via targeting mTOR/SREBP-1c axis in NAFLD mice.

The escalating incidences of non-alcoholic fatty liver disease (NAFLD) and associated metabolic disorders are global health concerns. Phloretin (Ph) is a natural phenolic compound, that exhibits a wide array of pharmacological actions including its efficacy towards NAFLD. However, poor solubility and bioavailability of phloretin limits its clinical translation. Here, to address this concern we developed an amorphous solid dispersion of phloretin (Ph-SD) using Soluplus® as a polymer matrix. We further performed solid-state characterization through SEM, P-XRD, FT-IR, and TGA/DSC analysis. Phloretin content, encapsulation efficiency, and dissolution profile of the developed formulation were evaluated through reverse phase HPLC. Finally, the oral bioavailability of Ph-SD and its potential application in the treatment of experimental NAFLD mice was investigated. Results demonstrated that the developed formulation (Ph-PD) augments the dissolution profile and oral bioavailability of the native phloretin (Ph). In NAFLD mice, histopathological studies revealed the preventive effect of Ph-SD on degenerative changes, lipid accumulation, and inflammation in the liver. Ph-SD also improved the serum lipid profile, ALT, and AST levels and lowered the interleukin-6 and tumor necrosis factor-α levels in the liver. Further, Ph-SD reduced fibrotic changes in the liver tissues and attenuates NAFLD progression by blocking the mTOR/SREBP-1c pathway. In a nutshell, the results of our study strongly suggest that Ph-SD has the potential to be a therapeutic candidate in the treatment of NAFLD and can be carried forward for further clinical studies.

Phloretin Ameliorates Succinate-Induced Liver Fibrosis by Regulating Hepatic Stellate Cells.

BACKGRUOUND: Hepatic stellate cells (HSCs) are the major cells which play a pivotal role in liver fibrosis. During injury, extracellular stimulators can induce HSCs transdifferentiated into active form. Phloretin showed its ability to protect the liver from injury, so in this research we would like to investigate the effect of phloretin on succinate-induced HSCs activation in vitro and liver fibrosis in vivo study. METHODS: In in vitro, succinate was used to induce HSCs activation, and then the effect of phloretin on activated HSCs was examined. In in vivo, succinate was used to generated liver fibrosis in mouse and phloretin co-treated to check its protection on the liver. RESULTS: Phloretin can reduce the increase of fibrogenic markers and inhibits the proliferation, migration, and contraction caused by succinate in in vitro experiments. Moreover, an upregulation of proteins associated with aerobic glycolysis occurred during the activation of HSCs, which was attenuated by phloretin treatment. In in vivo experiments, intraperitoneal injection of phloretin decreased expression of fibrotic and glycolytic markers in the livers of mice with sodium succinate diet-induced liver fibrosis. These results suggest that aerobic glycolysis plays critical role in activation of HSCs and succinate can induce liver fibrosis in mice, whereas phloretin has therapeutic potential for treating hepatic fibrosis. CONCLUSION: Intraperitoneal injection of phloretin attenuated succinate-induced hepatic fibrosis and alleviates the succinate-induced HSCs activation.

Concomitant inhibition of TLR-4 and SGLT2 by phloretin and empagliflozin prevents diabetes-associated ischemic acute kidney injury.

Toll-like receptor-4 (TLR4) and sodium-glucose co-transporter 2 (SGLT2) signaling is involved in the pathogenesis of diabetes-associated kidney diseases. The purpose of this study was to explore the role and effect of phloretin, a TLR4 inhibitor, as an adjuvant therapy to empagliflozin, an SGLT2 inhibitor, in ischemic acute kidney injury (AKI) under diabetic conditions. To achieve this, firstly we induced type 1 diabetes using streptozotocin (55 mg per kg per intraperitoneally (i.p.)) followed by performing bilateral ischemia-reperfusion kidney injury to induce AKI in male Wistar rats. Treatment with phloretin (50 and 100 mg per kg per orally) and empagliflozin (10 mgper kg per orally) alone or in combination was administered to the diabetic rats for 4 days and 1 h before surgery. Moreover, a hypoxia-reperfusion injury was induced using sodium azide in NRK52E cells under a hyperglycemic environment to mimic the in vivo model. The cells were treated with phloretin (50 µM) and empagliflozin (100 nM) for 24 h. For biochemical analysis, plasma and urine samples were used. The kidney tissues were used to perform immunoblotting, histopathology, and immunohistochemistry. Other experiments like immunofluorescence, cell viability assay, and flow cytometry analysis were performed using the in vitro samples. The study outcomes revealed that compared to monotherapy, combination therapy of phloretin and empagliflozin was significantly effective. Phloretin and empagliflozin target the HMGB1/TLR4/MyD88/IK-ß/α/NF-κB pathway to reduce inflammation and apoptosis, in addition to their antihyperglycemic effect. Thus, phloretin, a natural dietary supplement, as an adjuvant therapy to empagliflozin can be helpful to reduce empagliflozin-associated side effects, by reducing its clinical dose and increasing its therapeutic efficacy in AKI-diabetes comorbidity.

Phloretin and phlorizin mitigates inflammatory stress and alleviate adipose and hepatic insulin resistance by abrogating PPARγ S273-Cdk5 interaction in type 2 diabetic mice.

AIMS: The rising prevalence of type 2 diabetes mellitus (T2DM) and accompanying insulin resistance is alarming globally. Natural and synthetic agonists of PPARγ are potentially attractive candidates for diabetics and are known to efficiently reverse adipose and hepatic insulin resistance, but related side effects and escalating costs are the causes of concern. Therefore, targeting PPARγ with natural ligands is advantageous and promising approach for the better management of T2DM. The present research aimed to assess the antidiabetic potential of phenolics Phloretin (PTN) and Phlorizin (PZN) in type 2 diabetic mice. MAIN METHODS: In silico docking was performed to check the effect of PTN and PZN on PPARγ S273-Cdk5 interactions. The docking results were further validated in preclinical settings by utilizing a mice model of high fat diet-induced T2DM. KEY FINDINGS: Computational docking and further MD-simulation data revealed that PTN and PZN inhibited the activation of Cdk5, thereby blocking the phosphorylation of PPARγ. Our in vivo results further demonstrated that PTN and PZN administration significantly improved the secretory functions of adipocytes by increasing adiponectin and reducing inflammatory cytokine levels, which ultimately reduced the hyperglycaemic index. Additionally, combined treatment of PTN and PZN decreased in vivo adipocyte expansion and increased Glut4 expression in adipose tissues. Furthermore, PTN and PZN treatment reduced hepatic insulin resistance by modulating lipid metabolism and inflammatory markers. SIGNIFICANCE: In summary, our findings strongly imply that PTN and PZN are candidates as nutraceuticals in the management of comorbidities related to diabetes and its complications.

Therapeutic Potential and Pharmaceutical Development of a Multitargeted Flavonoid Phloretin.

Phloretin is a flavonoid of the dihydrogen chalcone class, present abundantly in apples and strawberries. The beneficial effects of phloretin are mainly associated with its potent antioxidant properties. Phloretin modulates several signaling pathways and molecular mechanisms to exhibit therapeutic benefits against various diseases including cancers, diabetes, liver injury, kidney injury, encephalomyelitis, ulcerative colitis, asthma, arthritis, and cognitive impairment. It ameliorates the complications associated with diabetes such as cardiomyopathy, hypertension, depression, memory impairment, delayed wound healing, and peripheral neuropathy. It is effective against various microbial infections including Salmonella typhimurium, Listeria monocytogenes, Mycobacterium tuberculosis, Escherichia coli, Candida albicans and methicillin-resistant Staphylococcus aureus. Considering the therapeutic benefits, it generated interest for the pharmaceutical development. However, poor oral bioavailability is the major drawback. Therefore, efforts have been undertaken to enhance its bioavailability by modifying physicochemical properties and molecular structure, and developing nanoformulations. In the present review, we discussed the pharmacological actions, underlying mechanisms and molecular targets of phloretin. Moreover, the review provides insights into physicochemical and pharmacokinetic characteristics, and approaches to promote the pharmaceutical development of phloretin for its therapeutic applications in the future. Although convincing experimental data are reported, human studies are not available. In order to ascertain its safety, further preclinical studies are needed to encourage its pharmaceutical and clinical development.

Phloretin mitigates oxidative injury, inflammation, and fibrogenic responses via restoration of autophagic flux in in vitro and preclinical models of NAFLD.

Nonalcoholic fatty liver disease (NAFLD) with growing incidences is a major health concern worldwide. Alteration in cellular redox homeostasis and autophagy plays a critical role in the progression of NAFLD to more severe outcomes. The lack of safe and effective therapy for the disease necessitates the exploration of new therapeutic compounds. Therefore, in the present study, we investigated the potential of phloretin to maintain redox equilibrium and prevent disease progression via modulation of autophagy in NAFLD. Free fatty acid exposed Huh7 cells were used to evaluate the efficacy of phloretin in vitro. Further, phloretin was administered orally to western diet induced NAFLD in C57BL/6J mice at different doses. The chronic exposure to fatty acids and the western diet triggered lipid accumulation in the Huh7 cells and western diet-fed mice liver, respectively. In addition, mitochondrial dysfunction, oxidative stress, inflammation and decreased hepatic autophagy were observed in disease condition. Phloretin encouraged autophagy mediated hepatic lipid clearance and restored mitochondrial membrane potential and redox homeostasis. It also reduced histological injury by reducing hepatic lipogenesis and facilitating fatty acid oxidation. Moreover, findings of the study also revealed the mitigatory effect of phloretin on inflammatory and fibrogenic markers. Altogether, the study suggested that phloretin effectively attenuates NAFLD progression via upregulating autophagy-mediated lipid breakdown and inhibits oxidative damage, hepatic inflammation and fibrosis.

The inhibition of GLUT1-induced glycolysis in macrophage by phloretin participates in the protection during acute lung injury.

The increased level of glycolysis in macrophage aggravates lipopolysaccharide (LPS)-induced acute lung injury (ALI). Glucose transporter 1 (GLUT1) serves as a ubiquitously expressed glucose transporter, which could activate inflammatory response by mediating glycolysis. Phloretin (PHL), an apple polyphenol, is also an inhibitor of GLUT1, possessing potent anti-inflammatory effects in various diseases. However, the potential role of PHL in ALI remains unclear till now. This study aims to investigate the impacts of PHL on ALI as well as its possible mechanisms. A mouse ALI model was established via intratracheal injection of LPS. LPS-induced primary macrophages were used to mimic in vitro ALI. Mice were pretreated with low or high dosage of PHL for 7 days via intragastric administration once a day before LPS injection. The results showed that PHL pretreatment significantly prevented LPS-induced lung pathological injury and inflammatory response. Meantime, PHL pretreatment also decreased the level of glycolysis in macrophage during ALI. In terms of mechanism, PHL inhibited the mRNA and protein expression of GLUT1. In vitro experiments further showed GLUT1 overexpression in macrophage by infection with lentivirus could abolish the inhibition of inflammation and glycolysis mediated by PHL, suggesting that GLUT1 was essential for the protection of PHL. Taken together, PHL pretreatment may protect against LPS-induced ALI by inhibiting glycolysis in macrophage in a GLUT1-dependent manner, which may be a candidate against ALI in the future.

Phloretin ameliorates diabetic nephropathy by inhibiting nephrin and podocin reduction through a non-hypoglycemic effect.

Phloretin is a dihydrochalcone flavonoid from natural plants, which has protective activities against oxidative stress and inflammation. To date, its effect on diabetic nephropathy (DN) has not been investigated. In this study, we examined the potential role of phloretin in diabetes-induced renal damage and associated mechanisms in a type 2 diabetes mellitus (T2DM) model induced by streptozotocin (STZ) and high-fat diet (HFD) in Apolipoprotein E knockout (ApoE-/-) mice. We found that daily treatment with a low dose (20 mg kg-1) of phloretin, as a dietary supplement, significantly alleviated polyuria, proteinuria, and glomerular histopathological changes in the T2DM mice, indicating a protective effect of phloretin on diabetic renal dysfunction. In the phloretin-treated T2DM mice, major metabolic parameters, including blood glucose levels, were not altered significantly, suggesting that the observed beneficial effects of phloretin may be due to a mechanism independent of blood glucose control. Further experiments revealed that phloretin had a protective effect on glomerular podocytes as indicated by ameliorated glomerular basement membrane (GBM) thickening and podocyte foot process effacement. Moreover, phloretin treatment restored levels of nephrin and podocin, two podocyte slit diaphragm proteins that were decreased in T2DM mice. Our results indicate that low-dose phloretin treatment has a protective effect on podocytes in DN via a non-hypoglycemic mechanism in preserving nephrin and podocin expression levels. These data suggest that phloretin may be exploited as a novel therapeutic agent for DN.

Phloretin attenuation of hepatic steatosis via an improvement of mitochondrial dysfunction by activating AMPK-dependent signaling pathways in C57BL/6J mice and HepG2 cells.

Phloretin, a dihydrochalcone, widely exists in the fruits of apple trees and crabapple trees (Malus prunifolia) with multiple biological activities. Presently, we studied the function of phloretin on the attenuation of hepatic steatosis and further explored the underlying mechanisms both in vitro and in vivo. Male C57BL/6J mice were fed a normal diet or high fat diet (HFD) with or without phloretin (100 mg kg-1) for 12 weeks. HepG2 cells were induced by 200 µM palmitic acid (PA) and co-incubated with phloretin (50 µM) for 24 h. The results showed that phloretin treatment significantly decreased the accumulation of lipids in the liver of the HFD-fed C57BL/6J mice and PA-induced HepG2 cells. Also, phloretin effectively ameliorated hepatic steatosis via promoting fatty acid ß-oxidation (FAO). This biological activity of phloretin was closely related to its capacity to improve mitochondrial dysfunction, including the promotion of mitochondrial biosynthesis and inhibition of mitochondrial swelling through the AMPK-dependent SIRT1/PGC-1α and SIRT3/CypD signaling pathways, respectively. These results demonstrate that phloretin effectively improves mitochondrial function and ameliorates HFD-induced hepatic steatosis through an AMPK-dependent signaling pathway.

Phloretin Ameliorates Acetic Acid Induced Colitis Through Modulation of Immune and Inflammatory Reactions in Rats.

BACKGROUND: Adverse effects associated with current therapy for Ulcerative colitis (UC) over prolonged treatment periods and the high relapse rate limit their use. Incorporating fruits as regular diet has beneficial role in the management of UC. Phloretin, a dihydrochalcone of apple is reported for its anti-oxidant and anti-inflammatory effects. Our study aims to evaluate the effectiveness of phloretin on experimentally induced ulcerative colitis in rats. METHODS: In vitro study was performed using Raw 264.7 cells stimulated with LPS (1µg/mL) and in in-vivo study, colitis was induced by intra rectal administration of 4% Acetic acid. Phloretin (50 mg/kg) was given orally for 3 days to Wistar rats after induction for the post-treatment group and 1 day before induction to the pre-treatment group. Macroscopical, biochemical and histopathological evaluations were performed to assess the effectiveness. RESULTS: A concentration dependent inhibition of MPO and iNOS activity was obtained in LPS stimulated neutrophil cells. Phloretin exerted ameliorative effect in both pre and post-treatment groups by restoring plasma ALP and LDH level and reduce inflammatory markers like myeloperoxidase, nitric oxide and eosinophil peroxidase level as well as downregulates colon ICAM-1 gene in acetic acid induced ulcerative colitis in rats. Antioxidative potency was confirmed by restoring tissue GSH level. Phloretin prevents mucosal damage and it was confirmed by histopathological analysis. CONCLUSION: Collectively, our findings provide evidence that phloretin might be useful as a natural therapeutic agent in the management of UC as well as may pose a promising outcome for future clinical usage.

Targeting Colorectal Cancer with Conjugates of a Glucose Transporter Inhibitor and 5-Fluorouracil.

Overexpression of glucose transporters (GLUTs) in colorectal cancer cells is associated with 5-fluorouracil (1, 5-FU) resistance and poor clinical outcomes. We designed and synthesized a novel GLUT-targeting drug conjugate, triggered by glutathione in the tumor microenvironment, that releases 5-FU and GLUTs inhibitor (phlorizin (2) and phloretin (3)). Using an orthotopic colorectal cancer mice model, we showed that the conjugate exhibited better antitumor efficacy than 5-FU, with much lower exposure of 5-FU during treatment and without significant side effects. Our study establishes a GLUT-targeting theranostic incorporating a disulfide linker between the targeting module and cytotoxic payload as a potential antitumor therapy.

Phloretin inhibited the pathogenicity and virulence factors against Candida albicans.

Oral candidiasis is one of the most common types of fungal infection caused by Candida albicans (C. albicans). The present study aims to investigate the antifungal effects of phloretin (a dihydrochalcone flavonoid) against the C. albicans pathogenicity. In this work, we treated C. albicans SC5314 with 37.28, 74.55, or 149.10 µg/mL (equivalent to 0.5×, 1× or 2× MIC) phloretin in vitro. Besides, we established a mice model of oral candidiasis by a sublingual infection of C. albicans suspension (1 × 107 colony-forming unit/mL), and mice were treated with phloretin (3.73 or 7.46 mg/mL, which were equivalent to 50× or 100× MIC) twice a day starting on day one post-infection. The results showed that the MIC of phloretin against C. albicans was 74.55 µg/mL. Phloretin exerted antifungal activity by inhibiting the biofilm formation and suppressing the yeast-to-hyphae transition upon the downregulation of hypha-associated genes including enhanced adherence to polystyrene 1, the extent of cell elongation gene 1, hyphal wall protein 1 gene, and agglutinin-like sequence gene 3. Next, phloretin repressed the secretion of proteases and phospholipases via reducing the expression of protease-encoding genes secreted aspartyl proteases (SAP)1 and SAP2, as well as phospholipase B1. Subsequently, the in vivo antifungal activity of phloretin was testified by the reverse of the enhanced lesion severity, inflammatory infiltration, and the increased colony-forming unit counts caused by C. albicans of tongue tissues in oral candidiasis mice. In conclusion, phloretin suppressed the pathogenicity and virulence factors against C. albicans both in vivo and in vitro.