Loxoprofen enhances intestinal barrier function via generation of its active metabolite by carbonyl reductase 1 in differentiated Caco-2 cells

Study of the stereospecificity in the biotransformation of the four isomers of loxoprofen sodium in rats by chiral HPLC

Loxoprofen sodium is a chiral drug with two chiral centers. In our previous work, we found that the elimination of its four isomers showed stereospecificity in rats, while how the stereospecific behavior occurred in vivo was unclear. To clarify this issue, each single isomer of loxoprofen sodium was prepared by a chiral semi-preparative high-performance liquid chromatography (HPLC) and then administered to rats. By analysis of each isomer in rat plasma utilizing an analytical chiral HPLC, it was discovered that the chiral inversion occurred only to its (2R)-isomers, one from (1'S,2R)- to (1'S,2S)-isomer and the other from (1'R,2R)- to (1'R,2S)-isomer. The reduction of α-substituted cyclopentanone occurred only to its (1'R)-isomers, with (1'R,2R)-isomer reduced to (2'S,1'R,2R)-trans-alcohol and (1'R,2S)- to (2'S,1'R,2S)-trans-alcohol. Interestingly, both the inversion and the reduction reaction occurred to its (1'R,2R)-isomer due to the special stereo-structure with both (2R)- and (1'R)-configuration, and conversely, neither of them occurred to its (1'S,2S)-isomer, which caused the significantly different elimination rate in vivo. These new findings were meaningful for evaluation of the safety and efficacy of chiral drugs.

Synthesis and pharmacokinetic properties of novel cPLA2α inhibitors with 1-(carboxyalkylpyrrolyl)-3-aryloxypropan-2-one structure

Indole-5-carboxylic acids with 3-aryloxy-2‑oxopropyl residues in position 1 have been shown to be potent inhibitors of cytosolic phospholipase A₂α (cPLA₂α), an enzyme involved in the formation of pro-inflammatory lipid mediators. Unfortunately, in animal experiments, only very low plasma concentrations could be achieved after peroral administration of this type of compound. Since insufficient metabolic stability was suspected as the cause, structural modifications were made to optimize this property. These included the conversion of the aromatic into an aliphatic carboxylic acid function as well as the rigidification of the lipophilic structural elements. A selected pyrrole-3-propionic acid was tested for its peroral in vivo bioavailability in mice. However, higher plasma concentrations could not be achieved also with this compound. Using the Caco2 cell permeation assay, substances investigated were found to be very good substrates for gastrointestinal efflux transporters, which explains their poor peroral absorption.

Aidi injection reduces doxorubicin-induced cardiotoxicity by inhibiting carbonyl reductase 1 expression

CONTEXT

Aidi injection (ADI), a traditional Chinese medicine antitumor injection, is usually combined with doxorubicin (DOX) for the treatment of malignant tumours. The cardiotoxicity of DOX is ameliorated by ADI in the clinic. However, the relevant mechanism is unknown.

OBJECTIVE

To investigate the effects of ADI on DOX-induced cardiotoxicity and its mechanism.

MATERIALS AND METHODS

ICR mice were randomly divided into six groups: control, ADI-L, ADI-H, DOX, DOX + ADI-L and DOX + ADI-H. DOX (i.p., 0.03 mg/10 g) was administered in the presence or absence of ADI (i.p., 0.1 or 0.2 mL/10 g) for two weeks. Heart pathology and levels of AST, LDH, CK, CK-MB and BNP were assessed. H9c2 cells were treated with DOX in the presence or absence of ADI (1, 4, 10%). Cell viability, caspase-3 activity, nuclear morphology, and CBR1 expression were then evaluated. DOX and doxorubicinol (DOXol) concentrations in heart, liver, kidneys, serum, and cells were analysed by UPLC-MS/MS.

RESULTS

High-dose ADI significantly reduced DOX-induced pathological changes and the levels of AST, LDH, CK, CK-MB and BNP to normal. Combined treatment with ADI (1, 4, 10%) improved the cell viability, and IC50 increased from 68.51 μM (DOX alone) to 83.47, 176.9, and 310.8 μM, reduced caspase-3 activity by 39.17, 43.96, and 61.82%, respectively. High-dose ADI inhibited the expression of CBR1 protein by 32.3%, reduced DOXol levels in heart, serum and H9c2 cells by 59.8, 72.5 and 48.99%, respectively.

DISCUSSION AND CONCLUSIONS

ADI reduces DOX-induced cardiotoxicity by inhibiting CBR1 expression, which provides a scientific basis for the rational use of ADI.