Current Drug Metabolism - Volume 26, Issue 2, 2025

Di-2-ethylhexylphthalate (DEHP) is utilized as a plasticizer in polyvinylchloride products (PVC). When medical devices like blood bags, tubes, and syringes are employed, DEHP leaches out of the PVC polymers and enters biological fluids through non-covalent binding. The presence of DEHP in peripheral blood leads to contamination of bone marrow. Previous research has demonstrated that this chemical induces oxidative stress, which adversely affects the viability and osteo-differentiation of bone marrow mesenchymal stem cells (BMSCs). Hence, our current study aims to utilize gallic acid (GA), a natural antioxidant, to alleviate the inhibitory effects of DEHP on BMSCs' osteogenic differentiation.

In osteogenic media, BMSCs extracted from Wistar rats were treated with 0.25 μM of GA and 100 μM of DEHP individually and in combination for 20 days. Then viability, total protein, malondialdehyde (MDA), total antioxidant capacity (TAC), catalase (CAT) and superoxide dismutase (SOD), alkaline phosphatase activity, production of collagen1A1 protein as well as expression of Bmp2 and 7, Smad1, Runx2, Oc, Alp, Col-1a1 genes were investigated.

The viability and differentiation ability of BMSCs was significantly (p<0.0001) decreased by DEHP, while GA significantly (P<0.0001) ameliorated the effect of DEHP. DEHP caused a significant decrease (P<0.0001) in the total protein and collagen-1A1 concentration, TAC and activity of antioxidant enzymes, but significantly (P<0.001) increased MDA level. In addition, DEHP caused a significant decrease in the expression of osteo-related genes. In the co-treatment group, GA mitigated the toxic effects of DEHP compared to the control group by inhibiting DEHP-induced oxidative stress and enhancing cell viability and osteo-differentiation properties.

These results confirm that GA reduces the negative effects of DEHP on the osteo-differentiation of BMSCs at the cellular level. However, further studies are necessary to validate these findings.

Timosaponin AIII, with poorly soluble characteristics, has a potential antidiabetic effect evaluated in vitro and in vivo. The major problem associated with poorly soluble drugs is very low bioavailability. This study aimed to investigate the metabolic profiles and antidiabetic mechanism of Timosaponin AIII.

The metabolic profiles of Timosaponin AIII in intestinal flora were analyzed using LC-MS/MS. Based on mass spectrometry analysis, network pharmacology combined with the GEO database was used to identify potential targets and elucidate the antidiabetic mechanism. Finally, the stability of compound-target complexes was further functionally confirmed by molecular docking.

As a result, 13 metabolites were identified. After the compound-target network, the genes of its metabolites increased by 60 compared to those of Timosaponin AIII. Subsequently, 13 core targets related to antidiabetic efficacy were identified through PPI network analysis. Key genes EGFR, MAPK1, and ICAM1 with strong binding efficiencies with metabolites were identified as crucial targets for the therapeutic effects of Timosaponin AIII. The KEGG analysis indicated that timosaponin AIII combated diabetes through various signaling pathways, including PI3K-Akt, FoxO, and HIF-1 signaling pathways, etc.

Taken together, this study clarified the mechanism of Timosaponin AIII against diabetes by identifying additional targets and pathways, and the importance of glycosidic structures. Otherwise, we might provide a solid foundation for the development of clinical applications of Timosaponin AIII.

The clearance of digoxin in obese patients with renal impairment is reduced, leading to elevated serum concentrations and increased risks of digoxin toxicity. However, the exact mechanism of such alterations in obese patients remains unclear. Previous studies have suggested that the organic anion transporting polypeptide 4c1 (Oatp4c1, Slco4c1) mediates the elimination of digoxin at the basal membrane of the proximal tubule (PT), indicating its potential role in the pharmacokinetic changes in obese patients. This study aims to investigate the effects of a high-fat diet HFD on digoxin pharmacokinetics and transporter expression in mouse models and further analyze its significance by detecting the expression of transporters in human renal tissue samples.

First, HFD-induced obese mouse model was established. Mice were intraperitoneally injected with digoxin, and 24-hour urine samples and blood samples at five time points were collected. Pharmacokinetic evaluation was performed using liquid chromatography-tandem mass spectrometry. Renal pathological changes and the expression of digoxin transporters (Oatp4c1 and P-glycoprotein (P-gp)) were assessed using histological staining, Western blots (WB), as well as quantitative polymerase chain reaction (qPCR). Human renal pathologic alterations and expression of transporter proteins showed consistency with the results of animal experiments. To explore the potential use of gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic acid (Gd-EOB-DTPA) as a marker for Oatp4c1 function, drug interactions between digoxin and Gd-EOB-DTPA were assessed in mice.

HFD-induced obese mice showed significant increases in body weight, blood glucose, and triglyceride, along with elevated blood concentration of digoxin, increased areas under the curve, reduced renal clearance rate (CLr), and prolonged half-life (t1/2). Histological staining revealed proximal tubular epithelial cell detachment and slight fibrosis in the kidney of the HFD group, with decreased expression of villin, the protein marker for PT. Immunofluorescent staining and Western blots for digoxin transporters showed a significant reduction of Oatp4c1 and P-gp proteins, suggesting that the renal elimination of digoxin was affected by the reduced level of Oatp4c1 and P-gp proteins. Co-administration of digoxin and Gd-EOB-DTPA resulted in a reduced clearance of Gd-EOB-DTPA, suggesting that both share the same transporter. The blood concentration of Gd-EOB-DTPA was higher (77.5%) in the HFD group. Renal magnetic resonance imaging (MRI) intensity was lower in the HFD group after Gd-EOB-DTPA administration compared to the Chow group.

Obesity-induced kidney damage results in decreased Oatp4c1 and P-gp expression and function in PT, resulting in a reduction of digoxin renal clearance. The inhibition of Gd-EOB-DTPA clearance by digoxin co-administration and the increased Gd-EOB-DTPA blood concentration in the HFD group both suggest its potential use in characterizing the Oatp4c1 function in vivo.