Search Results (18)

Multidrug resistance (MDR) poses a significant challenge in cancer therapy, often leading to treatment failure and relapse. ATP-binding cassette (ABC) transporters, particularly ABCG2, play a pivotal role in MDR development by actively expelling chemotherapeutic agents from cancer cells. This study investigates the effects of two groups of primaquine derivatives—fumardiamides (1a–d) and bis-ureas (2a, b), both bearing halogenated benzene rings—on the activity of P-glycoprotein (P-gp) and ABCG2. Their potential to reverse MDR was evaluated through a series of functional assays aimed at comparing transporter–compound interactions. The results indicated that fumardiamide derivatives, specifically 1a, 1b, and 1d, exhibited potent inhibition of ABCG2 while having no effect on P-gp, demonstrating a selective mode of action. The tested derivatives displayed low to moderate cytotoxicity and did not affect ABCG2 expression or localization. Moreover, these compounds enhanced the sensitivity of drug-resistant cancer cell lines to mitoxantrone, underscoring their potential to overcome ABCG2-mediated MDR. These findings suggest that chemical modifications of primaquine, particularly the incorporation of fumardiamide moieties, confer novel biological properties, providing promising leads for the development of selective ABCG2 inhibitors. Full article

Background/Objectives: Urea transporters (UTs) play an important role in the urine-concentrating mechanism and have been regarded as a novel drug target for developing salt-sparing diuretics. Our previous studies found that diarylamides 1H and 25a are specific UT inhibitors and have oral diuretic activity. However, these compounds necessitate further optimization and comprehensive druggability studies. Methods: The optimal compound was identified through structural optimization. Experiments were conducted to investigate its UT inhibitory activity and evaluate its diuretic effect. Furthermore, disease models were utilized to assess the compound’s efficacy in treating hyponatremia. Pharmacokinetic studies were performed to examine its metabolic stability, and toxicity tests were conducted to evaluate its safety. Results: Based on the chemical structure of compound 25a, we synthesized a novel diarylamide compound, E3, by introducing a benzenesulfonamide group into its side chain. E3 exhibited dose-dependent inhibition of UT at the nanomolar level and demonstrated oral diuretic activity without causing electrolyte excretion disorders in both mice and rats. Experiments on UT-B^−/− and UT-A1^−/− mice indicated that E3 enhances the diuretic effect primarily by inhibiting UT-A1 more effectively than UT-B. Furthermore, E3 displayed good metabolic stability and favorable pharmacokinetic characteristics. E3 significantly ameliorated hyponatremia through diuresis in a rat model. Importantly, E3 did not induce acute oral toxicity, subacute oral toxicity, genotoxicity, or cardiotoxicity. Conclusions: Our study confirms that E3 exerts a diuretic effect by specifically inhibiting UTs and has good druggability, which offers potential for E3 to be developed into a new diuretic for the treatment of hyponatremia. Full article

Celery (Apium graveolens L.) seeds are rich in carbohydrates and protein, and they are widely used in diuretic drugs among Uyghur doctors. However, the diuretic mechanism is still unclear. To explore the possible diuretic mechanism of celery seeds, urea transporters, a potential diuresis-related target, are used in this study. Urea transporters (UTs) play a key role of urine concentration. Selective knockout of UTs can concentrate urea without affecting water and electrolytes, resulting in selective diuresis, which is a promising new diuretic target. In the present study, we obtained different polar fractions by extracting and separating celery seed extract, characterized its polar fractions using UPLC-TOF-MS, and verified its action using an erythrocyte lysis model in vitro. Then, it was found that the isovaleric acid p-tolylester exhibited moderate activity (IC₅₀ = 80.34 μM). Finally, its inhibitory effect on UT-B was investigated by using molecular docking, a pharmacophore model, and molecular dynamics simulations. This study provides a new approach to developing novel diuretics. Full article

Background and Objectives: Peritoneal dialysis (PD) is a renal replacement therapy modality in which the dialysis dose can be individually adapted according to the patients’ residual kidney function (RKF). RKF is a crucial factor for technique and patient survival. Pharmacological strategies aimed at slowing the loss of RKF in patients on PD are limited. Therefore, we aimed to assess the potential effects and safety of sodium–glucose cotransporter 2 (SGLT-2) inhibitors on the preservation of RKF in patients with and without type 2 diabetes mellitus (T2DM) on PD during an average follow-up of 6 months. Materials and Methods: In this retrospective observational, single-center study on real-world data, we included patients from the Peritoneal Dialysis Unit of the Hospital General Universitario de Ciudad Real, who started treatment with SGLT-2 inhibitors during the period from December 2022 to December 2023. Data on analytical and clinical parameters, RKF, and peritoneal membrane transport function were retrospectively collected at months 0, 3, and 6. Results: Out of 31 patients in our unit, 16 prevalent patients initiated treatment with SGLT-2 inhibitors (13 empagliflozin and 3 dapagliflozin). A total of 62.5% were male and the mean age was 67.3 years. The baseline peritoneal ultrafiltration was higher in the non-diabetic patient (NDMP) group than in the diabetic patient (DMP) group. However, the residual diuresis volume, 24 h residual renal clearance rate of urea in urine, and 24 h proteinuria were higher in the DMP group than in the NDMP group. At the sixth month, patients in both groups preserved RKF and diuresis, with a trend towards a non-significant reduction in proteinuria and blood pressure. Only two patients of the DMP group presented adverse effects. Conclusions: The use of SGLT-2 inhibitors in our sample of patients with and without T2DM on PD appears to be safe and effective to preserve RKF. Full article

Hyponatremia (hypo-osmolality) is a disorder of water homeostasis due to abnormal renal diluting capacity. The body limits the degree to which serum sodium concentration falls through a mechanism called “vasopressin escape”. Vasopressin escape is a process that prevents the continuous decrease in serum sodium concentration even under conditions of sustained high plasma vasopressin levels. Previous reports suggest that aldosterone may be involved in the vasopressin escape mechanism. The abilities of aldosterone synthase (Cyp11b2) knockout and wild-type mice to escape from vasopressin were compared. Wild-type mice escaped while the aldosterone synthase knockout mice did not. Both the water channel aquaporin 2 (AQP2) and the urea transporter UT-A1 protein abundances were higher in aldosterone synthase knockout than in wild-type mice at the end of the escape period. Vasopressin escape was also blunted in rats given spironolactone, a mineralocorticoid receptor blocker. Next, the role of the phosphatase, calcineurin (protein phosphatase 2B, PP2B), in vasopressin escape was studied since aldosterone activates calcineurin in rat cortical collecting ducts. Tacrolimus, a calcineurin inhibitor, blunted vasopressin escape in rats compared with the control rats, increased UT-A1, AQP2, and pS256-AQP2, and decreased pS261-AQP2 protein abundances. Our results indicate that aldosterone regulates vasopressin escape through calcineurin-mediated protein changes in UT-A1 and AQP2. Full article

Resveratrol has anti-inflammatory, anti-cancer, and anti-aging pharmacological activities. There is currently a gap in academic research regarding the uptake, transport, and reduction of H₂O₂-induced oxidative damage of resveratrol in the Caco-2 cell model. This study investigated the role of resveratrol in the uptake, transport, and alleviation of H₂O₂-induced oxidative damage in Caco-2 cells. In the Caco-2 cell transport model, it was observed that the uptake and transport of resveratrol (10, 20, 40, and 80 μM) were time dependent and concentration dependent. Different temperatures (37 °C vs. 4 °C) could significantly affect the uptake and transportation of resveratrol. The apical to basolateral transport of resveratrol was markedly reduced by STF-31, a GLUT1 inhibitor, and siRNA intervention. Furthermore, resveratrol pretreatment (80 μM) improves the viability of Caco-2 cells induced by H₂O₂. In a cellular metabolite analysis combined with ultra-high performance liquid chromatography-tandem mass spectrometry, 21 metabolites were identified as differentials. These differential metabolites belong to the urea cycle, arginine and proline metabolism, glycine and serine metabolism, ammonia recycling, aspartate metabolism, glutathione metabolism, and other metabolic pathways. The transport, uptake, and metabolism of resveratrol suggest that oral resveratrol could prevent intestinal diseases caused by oxidative stress. Full article

Soybean plants can fix atmospheric N₂ in the root nodule, a symbiotic organ with rhizobia. The primary forms of N transported from N₂ fixation are ureides, allantoate, and allantoin, supplemented with asparagine. The nitrate absorbed in the roots is transported to the shoots in the forms of NO₃⁻ and asparagine with a little portion of ureides. The concentrations of N-metabolites were analyzed by capillary electrophoresis after supplying various concentrations of urea, precursors of ureides, and allopurinol, an inhibitor of xanthine dehydrogenase, to investigate the ureide synthesis pathway in the roots. When the non-nodulated soybean plants were treated with 0–5 mM of urea, the concentrations of asparagine and glutamine in the xylem sap and the roots increased remarkably. In addition, allantoate concentration increased with the urea concentrations becoming higher. Allopurinol inhibited the accumulation of allantoate but did not affect the asparagine and glutamine accumulation in roots, stems, leaves, and xylem sap, supporting that allantoate is synthesized by purine degradation in roots the same as in the nodules. When ureide precursors were supplied to the nodulated soybean plants, the concentrations of asparagine and glutamine in the xylem sap and roots increased, suggesting that the ureide precursors were absorbed and assimilated to amides in the roots. Full article

Obesity is a major public health problem worldwide, and it is associated with many diseases and abnormalities, most importantly, type 2 diabetes. The visceral adipose tissue produces an immense variety of adipokines. Leptin is the first identified adipokine which plays a crucial role in the regulation of food intake and metabolism. Sodium glucose co-transport 2 inhibitors are potent antihyperglycemic drugs with various beneficial systemic effects. We aimed to investigate the metabolic state and leptin level among patients with obesity and type 2 diabetes mellitus, and the effect of empagliflozin upon these parameters. We recruited 102 patients into our clinical study, then we performed anthropometric, laboratory, and immunoassay tests. Body mass index, body fat, visceral fat, urea nitrogen, creatinine, and leptin levels were significantly lower in the empagliflozin treated group when compared to obese and diabetic patients receiving conventional antidiabetic treatments. Interestingly, leptin was increased not only among obese patients but in type 2 diabetic patients as well. Body mass index, body fat, and visceral fat percentages were lower, and renal function was preserved in patients receiving empagliflozin treatment. In addition to the known beneficial effects of empagliflozin regarding the cardio-metabolic and renal systems, it may also influence leptin resistance. Full article

Ascites is a typical symptom of liver cirrhosis that is caused by a variety of liver diseases. Ascites severely affects the life quality of patients and needs long-term treatment. 25a is a specific urea transporter inhibitor with a diuretic effect that does not disturb the electrolyte balance. In this study, we aimed to determine the therapeutic effect of 25a on ascites with a dimethylnitrosamine (DMN)-induced cirrhotic rat model. It was found that 100 mg/kg of 25a significantly increased the daily urine output by 60% to 97% and reduced the daily abdominal circumference change by 220% to 260% in cirrhotic rats with a water intake limitation. The 25a treatment kept the serum electrolyte levels within normal ranges in cirrhotic rats. The H&E and Masson staining of liver tissue showed that 25a did not change the cirrhotic degree. A serum biochemical examination showed that 25a did not improve the liver function in cirrhotic rats. A Western blot analysis showed that 25a did not change the expression of fibrosis-related marker protein α-SMA, but significantly decreased the expressions of type I collagen in the liver of cirrhotic rats, indicating that 25a did not reverse cirrhosis, but could slow the cirrhotic progression. These data indicated that 25a significantly reduced ascites via diuresis without an electrolyte imbalance in cirrhotic rats. Our study provides a proof of concept that urea transporter inhibitors might be developed as novel diuretics to treat cirrhotic ascites. Full article

The aim of this study is to evaluate the anti-hyperuricemia effect and clarify the possible mechanisms of flavonoids and phenolics of MOL (MOL-FP) in mice. Hyperuricemia mice were generated via intraperitoneal (i.p.) administration of potassium oxonate (PO) and oral gavage (p.o.) of hypoxanthine (HX). Serum uric acid (UA), weight, serum XO activity, hepatic XO activity, urea nitrogen (BUN), creatinine (CRE), serum AST level, serum ALT level, mRNA expression of renal urate-anion transporter 1 (URAT1), glucose transporter 9 (GLUT9), organic anion transporters 1 (OAT1), organic anion transporters 3 (OAT3), and ATP-binding cassette transporter G2 (ABCG2) were determined. The molecular docking was conducted using AutoDock Vina 1.2.0 to screen potential XO inhibitors in MOL-FP. Serum metabolomics was established to collect the metabolic profiles of mice and explore the metabolic changes that occurred after MOL-FP treatment. MOL-FP could notably reduce the serum UA level of hyperuricemia mice by inhibiting XO activity and regulating renal urate transporters. Molecular docking studies indicated that 5-p-coumaroylquinic acid, 3-p-coumaroylquinic acid, and catechin could be potential XO inhibitors. Besides, MOL-FP prevented the pathological process of hyperuricemia by regulating biomarkers associated with purine metabolism, amino acid metabolism, and lipid metabolism. Full article

Urea transporters (UTs) are a kind of transmembrane protein that specifically permeate urea, and play an important role in the mechanism of urine concentration. Selective knockout of UT can concentrate urea without affecting water and electrolytes, resulting in selective diuresis, which is a promising new diuretic target. Most of the currently reported UT inhibitors are obtained from small molecular libraries screened. We subjected the methanolic extract of celery seed to silica gel column chromatography analysis, and screened the column chromatographic fractions of celery seed for UT-B inhibitory activity using the reported erythrocyte lysis model. The UT-B inhibitory activity was also screened for the fractions of celery seed separated by column chromatography, using the reported erythrocyte lysis model. The chemical composition of the active site was identified using UPLC-TOF-MS, and the active compounds were selected in combination with molecular docking and ADMET prediction. Screening of the extracted parts of celery seed, using an erythrocyte lysis model, yielded nine small molecules with good inhibitory activity, namely esters, phenols, and organic acids. This experiment shows that compounds with UT-B inhibitory effects can be found in ethnic medicinal materials, which not only provides new ideas for the discovery of UT-B inhibitors, but also contributes to the development of ethnic medicines. Full article

Gliflozins (sodium-glucose transporter-2 inhibitors) exhibited renoprotective effects not only in diabetic but also in non-diabetic patients with chronic kidney disease (CKD). Controversial results were reported in experimental non-diabetic models of CKD. Therefore, we examined empagliflozin effects in three CKD models, namely, in fawn-hooded hypertensive (FHH) rats, uninephrectomized salt-loaded (UNX + HS) rats, and in rats with Goldblatt hypertension (two-kidney, one-clip 2K1C) that were either untreated or treated with empagliflozin (10 mg/kg/day) for eight weeks. Plethysmography blood pressure (BP) was recorded weekly, and renal parameters (proteinuria, plasma urea, creatinine clearance, and sodium excretion) were analyzed three times during the experiment. At the end of the study, blood pressure was also measured directly. Markers of oxidative stress (TBARS) and inflammation (MCP-1) were analyzed in kidney and plasma, respectively. Body weight and visceral adiposity were reduced by empagliflozin in FHH rats, without a significant effect on BP. Experimentally induced CKD (UNX + HS and 2K1C) was associated with a substantial increase in BP and relative heart and kidney weights. Empagliflozin influenced neither visceral adiposity nor BP in these two models. Although empagliflozin increased sodium excretion, suggesting effective SGLT-2 inhibition, it did not affect diuresis in any experimental model. Unexpectedly, empagliflozin did not provide renoprotection because proteinuria, plasma urea, and plasma creatinine were not lowered by empagliflozin treatment in all three CKD models. In line with these results, empagliflozin treatment did not decrease TBARS or MCP-1 levels in either model. In conclusion, empagliflozin did not provide the expected beneficial effects on kidney function in experimental models of CKD. Full article

Sodium glucose cotransporter, type 2 inhibitors, such as Empagliflozin, are protective of the kidneys by unclear mechanisms. Our aim was to determine how Empagliflozin affected kidney cortical metabolome and lipidome in mice. Adult male TALLYHO mice (prone to obesity) were treated with a high-milk-fat diet, or this diet containing Empagliflozin (0.01%), for 8 weeks. Targeted and untargeted metabolomics and lipidomics were conducted on kidney cortex by liquid chromatography followed by tandem mass-spectroscopy. Metabolites were statistically analyzed by MetaboAnalyst 5.0, LipidSig (lipid species only) and/or CEU Mass Mediator (untargeted annotation). In general, volcano plotting revealed oppositely skewed patterns for targeted metabolites (primarily hydrophilic) and lipids (hydrophobic) in that polar metabolites showed a larger number of decreased species, while non-polar (lipids) had a greater number of increased species (>20% changed and/or raw p-value < 0.05). The top three pathways regulated by Empagliflozin were urea cycle, spermine/spermidine biosynthesis, and aspartate metabolism, with an amino acid network being highly affected, with 14 of 20 classic amino acids down-regulated. Out of 75 changed polar metabolites, only three were up-regulated, i.e., flavin mononucleotide (FMN), uridine, and ureidosuccinic acid. Both FMN and uridine have been shown to be protective of the kidney. Scrutiny of metabolites of glycolysis/gluconeogenesis/Krebs cycle revealed a 20–45% reduction in several species, including phosphoenolpyruvate (PEP), succinate, and malic acid. In contrast, although overall lipid quantity was not higher, several lipid species were increased by EMPA, including those of the classes, phosphatidic acids, phosphatidylcholines, and carnitines. Overall, these analyses suggest a protection from extensive metabolic load and the corresponding oxidative stress with EMPA in kidney. This may be in response to reduced energy demands of the proximal tubule as a result of inhibition of transport and/or differences in metabolic pools available for metabolism. Full article

Urea transporter (UT) inhibitors are a class of promising novel diuretics that do not cause the imbalance of Na⁺, K⁺, Cl⁻, and other electrolytes. In our previous studies, 25a, a promising diuretic candidate inhibiting UT, was discovered and showed potent diuretic activities in rodents. Here, a sensitive liquid chromatography–tandem mass spectrometry method for the quantitation of 25a in rat plasma, urine, feces, bile, and tissue homogenates was developed and validated to support the preclinical pharmacokinetic studies. The tissue distribution, excretion, and plasma protein binding were investigated in rats. After a single oral dose of 25a at 25, 50, and 100 mg/kg, the drug exposure increased linearly with the dose. The drug accumulation was observed after multiple oral doses compared to a single dose. In the distribution study, 25a exhibited a wide distribution to tissues with high blood perfusion, such as kidney, heart, lung, and spleen, and the lowest distribution in the brain and testis. The accumulative excretion rate of 25a was 0.14%, 3.16%, and 0.018% in urine, feces, and bile, respectively. The plasma protein binding of 25a was approximately 60% in rats and 40% in humans. This is the first study on the preclinical pharmacokinetic profiles of 25a. Full article

Quinoa is a climate resilience potential crop for food security due to high nutritive value. However, crop variable response to nitrogen (N) use efficiency may lead to affect grain quality and yield. This study compared the performance of contrasting quinoa genotypes (UAF Q-7, EMS-line and JQH1) to fertilizer urea enriched with urease and nitrification inhibitors (NIs; 1% (w/w) thiourea + boric acid + sodium thiosulphate), ordinary urea and with no N as control. Application of NIs-enriched urea improved plant growth, N uptake and chlorophyll values in quinoa genotype UAF-Q7 and JHQ1, however, highest nitrate reductase (NR) activity was observed in EMS-line. Quinoa plants supplied with NIs-enriched urea also completed true and multiple leaf stage, bud formation, flowering, and maturity stages earlier than ordinary urea and control, nevertheless, all quinoa genotypes reached true and multiple leaf stage, flowering and maturity stages at same time. Among photosynthetic efficiency traits, application of NIs-enriched urea expressed highest photosynthetic active radiations (PAR), electron transport rate (ETR), current fluorescence (Ft) and reduced quantum yield (Y) in EMS line. Nitrogen treatments had no significant difference for panicle length, however, among genotypes, UAF-Q7 showed highest length of panicle followed by others. Among yield attributes, NIs-enriched urea expressed maximum 1000-seed weight and seed yield per plant in JQH-1 hybrid and EMS-line. Likely, an increase in quinoa grain protein contents was observed in JQH-1 hybrid for NIs-enriched urea. In conclusion, NIs-enriched urea with urease and nitrification inhibitors simultaneously can be used to improve the N uptake, seed yield and grain protein contents in quinoa, however, better crop response was attributed to enhanced plant growth and photosynthetic efficiency. Full article