Liver uptake of cefditoren is mediated by OATP1B1 and OATP2B1 in humans and Oatp1a1, Oatp1a4, and Oatp1b2 in rats

Predictive Modeling of HMG-CoA Reductase Inhibitory Activity and Design of New HMG-CoA Reductase Inhibitors

As blood cholesterol increases, it accumulates in the intima of blood vessels, elevating the risk of atherosclerosis and coronary artery disease. Drugs that inhibit enzymes essential for cholesterol synthesis are effective in improving blood cholesterol levels. Statins are used to treat hypercholesterolemia as they inhibit 3-hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase (HMGR), the rate-limiting enzyme in cholesterol synthesis. Statins are known to exert their effects by translocating to the liver, where they are taken up by the organic anion transporting polypeptide 1B1 (OATP1B1). Therefore, we hypothesized that a compound with high HMGR inhibitory activity and high affinity for OATP1B1 would be an excellent new therapeutic agent for hypercholesterolemia with increased liver selectivity and fewer side effects. In this study, we developed two models for predicting HMGR inhibitory activity and OATP1B1 affinity to propose the chemical structure of a new therapeutic agent for hypercholesterolemia with both high inhibitory activity and high liver selectivity. HMGR inhibitory activity and OATP1B1 affinity prediction models were constructed with high prediction accuracy for the test data: r2 = 0.772 and 0.768, respectively. New chemical structures were then input into these models to search for candidate compounds. We found compounds with higher HMGR inhibitory activity and OATP1B1 affinity than rosuvastatin, the most recently developed statin drug, and compounds that did not have a common structure of statins with high HMGR inhibitory activity.

Transporters (OATs and OATPs) contribute to illustrate the mechanism of medicinal compatibility of ingredients with different properties in yuanhuzhitong prescription

Various medicinal ingredients with different tastes are combined according to the theory of compatibility in Chinese materia medica to achieve a better efficacy, while the mechanism was not very clear. Here, the authors studied the interaction between ingredients and human transporters such as the kidney transporters OAT1 and OAT3, the liver transporters OATP1B1 and OATP1B3, and the intestine transporter OATP2B1 to discern the compatibility mechanism of ingredients with different tastes in the Yuanhuzhitong preparation (YHP) comprising Corydalis yanhusuo (CYH) and Angelica dahurica (AD), which could relieve pain by restraining the central system. The results show that tetrahydropalmatine (TDE), the major component of CYH, could be transported by OAT3 into kidney, OATP1B1 and OATP1B3 into liver, while imperatorin (IPT) and isoimperatorin (ISP), the two key components of AD, and AD extract showed strong inhibition to OAT1 and OAT3. What's more, AD extract also exerted strongly inhibition to human transporters OATP1B1 and OATP1B3. It was also detected that IPT, ISP, and AD extract significantly downregulated the expression of Oatp1a1, Oatp1a4, and Oatp1b2 of liver in mice. The in vivo results show that the concentration of TDE in liver and kidney significantly decreased, while the TDE concentration in blood and brain were both significantly enhanced in the presence of IPT, ISP, and AD extract. These results suggest that the ingredients in AD with pungent taste could enhance the exposure of TDE in blood and brain by inhibiting the uptake of TDE in liver and kidney. That is to say, TDE with bitter taste could "flood up" into the central nervous system to play its therapeutic effect by the cut-off of that into liver and kidney in the presence of ingredients within AD. This paper not only proves the meridian distribution of CYH in liver and kidney with the role of OAT3, OATP1B1, and OATP1B3, but also illustrates how to improve the efficacy of CYH by reasonable compatibility with AD. This study may offer a valuable clue to illustrate the mechanism of compatibility theory.

Design, Synthesis, and Pharmacological Evaluation of Potent Positive Allosteric Modulators of the Glucagon-like Peptide-1 Receptor (GLP-1R)

The therapeutic success of peptidic GLP-1 receptor agonists for treatment of type 2 diabetes mellitus (T2DM) motivated our search for orally bioavailable small molecules that can activate the GLP-1 receptor (GLP-1R) as a well-validated target for T2DM. Here, the discovery and characterization of a potent and selective positive allosteric modulator (PAM) for GLP-1R based on a 3,4,5,6-tetrahydro-1H-1,5-epiminoazocino[4,5-b]indole scaffold is reported. Optimization of this series from HTS was supported by a GLP-1R ligand binding model. Biological in vitro testing revealed favorable ADME and pharmacological profiles for the best compound 19. Characterization by in vivo pharmacokinetic and pharmacological studies demonstrated that 19 activates GLP-1R as positive allosteric modulator (PAM) in the presence of the much less active endogenous degradation product GLP1(9-36)NH₂ of the potent endogenous ligand GLP-1(7-36)NH₂. While these data suggest the potential of small molecule GLP-1R PAMs for T2DM treatment, further optimization is still required towards a clinical candidate.

Pharmacokinetic changes of cefdinir and cefditoren and its molecular mechanisms in acute kidney injury in rats

OBJECTIVES

Acute kidney injury (AKI) was a common organ damage that often occurred after cisplatin. This study was aimed at investigating the pharmacokinetic changes of cefdinir and cefditoren in AKI rats, and elucidating the possible molecular mechanisms.

METHODS

The renal injury model was established by intraperitoneal injection of cisplatin (12 mg/kg). Plasma creatinine, blood urea nitrogen, the mRNA expression of Kim-1, hematoxylin and eosin staining and Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) assay were used to measure the degree of renal damage. On this basis, the pharmacokinetic changes of cefdinir and cefditoren were investigated in normal and AKI rats. RT-PCR and Western blot were performed to clarify the molecular mechanisms for the changes in the related transporters expression.

KEY FINDINGS

The cumulative urinary excretion of cefdinir was significantly decreased and the plasma concentration was remarkably increased in AKI rats. The expression of organic anion transporter 1 (Oat1) and Oat3 in kidney was decreased. However, pharmacokinetics of cefditoren was not influenced. The expression of organic anion-transporting polypeptide 1a1 (Oatp1a1), Oatp1a4, Oatp1b2 and multidrug resistance-associated protein 2 (Mrp2) in liver was unchanged in AKI rats.

CONCLUSIONS

The molecular mechanism of decreased expression of Oat1 and Oat3 was achieved through activating p53, and then increasing the expression of Bax and Caspase-3 and down regulating Bcl-2 in AKI rats. On this basis, the cumulative urinary excretion of cefdinir was significantly decreased and the plasma concentration of cefdinir was remarkably increased in AKI rats. However, the pharmacokinetic changes of cefditoren were not observed. Accordingly, cephalosporin antibiotics such as cefditoren should be firstly selected for the treatment in patients with AKI in clinic.