Stir-fried Semen Armeniacae Amarum Suppresses Aristolochic Acid I-Induced Nephrotoxicity and DNA Adducts

OBJECTIVE

To investigate the protective effects of stir-fried Semen Armeniacae Amarum (SAA) against aristolochic acid I (AAI)-induced nephrotoxicity and DNA adducts and elucidate the underlying mechanism involved for ensuring the safe use of Asari Radix et Rhizoma.

METHODS

In vitro, HEK293T cells overexpressing Flag-tagged multidrug resistance-associated protein 3 (MRP3) were constructed by Lentiviral transduction, and inhibitory effect of top 10 common pairs of medicinal herbs with Asari Radix et Rhizoma in clinic on MRP3 activity was verified using a self-constructed fluorescence screening system. The mRNA, protein expressions, and enzyme activity levels of NAD(P)H quinone dehydrogenase 1 (NQO1) and cytochrome P450 1A2 (CYP1A2) were measured in differentiated HepaRG cells. Hepatocyte toxicity after inhibition of AAI metabolite transport was detected using cell counting kit-8 assay. In vivo, C57BL/6 mice were randomly divided into 5 groups according to a random number table, including: control (1% sodium bicarbonate), AAI (10 mg/kg), stir-fried SAA (1.75 g/kg) and AAI + stir-fried SAA (1.75 and 8.75 g/kg) groups, 6 mice in each group. After 7 days of continuous gavage administration, liver and kidney damages were assessed, and the protein expressions and enzyme activity of liver metabolic enzymes NQO1 and CYP1A2 were determined simultaneously.

RESULTS

In vivo, combination of 1.75 g/kg SAA and 10 mg/kg AAI suppressed AAI-induced nephrotoxicity and reduced dA-ALI formation by 26.7%, and these detoxification effects in a dose-dependent manner (P<0.01). Mechanistically, SAA inhibited MRP3 transport in vitro, downregulated NQO1 expression in vivo, increased CYP1A2 expression and enzymatic activity in vitro and in vivo, respectively (P<0.05 or P<0.01). Notably, SAA also reduced AAI-induced hepatotoxicity throughout the detoxification process, as indicated by a 41.3% reduction in the number of liver adducts (P<0.01).

CONCLUSIONS

Stir-fried SAA is a novel drug candidate for the suppression of AAI-induced liver and kidney damages. The protective mechanism may be closely related to the regulation of transporters and metabolic enzymes.

Synthesis and biological evaluation of novel quinoline analogs of ketoprofen as multidrug resistance protein 2 (MRP2) inhibitors

Objectives

A new series of quinoline analogs of ketoprofen was designed and synthesized as multidrug resistance protein 2 (MRP2) inhibitors using ketoprofen as the lead compounds.

Materials and Methods

The cytotoxic activity of the compounds was evaluated againt two cancer cell lines including A2780/RCIS (MRP2-overexpressing ovarian carcinoma), A2780, drug-sensitive ovarian carcinoma using MTT assay. Compounds showing low toxicity in MTT test were selected to investigate their MRP inhibition activity. MRP2 inhibitory potency was evaluated by determination of the uptake amount of fluorescent 5-carboxy fluorescein diacetate (5-CFDA) substrate, by A2780/RCIS in the presence of the selected compounds. Mode of interaction between synthesized ligands and homology modeled MRP2 was investigated by MOE software.

Results

Compound 6d, a 4-carboxy quinoline possessing dimethoxy phenyl in position 2 of quinoline ring, showed the most MRP2 inhibition activity among all the quinolines and more than the reference drug ketoprofen. MRP2 inhibition activity of compound 7d was less in comparison to that of compound 6d, indicating that carboxyl group in position 4 of quinoline may interact with MRP2. Docking studies showed that compound 7d methyl ester of 6d, interacted less compared to its parent 6d, which is consistent with biological results.

Conclusion

This study indicates that 6- or 8-benzoyl-2-arylquinoline is a suitable scaffold to design MRP2 inhibitors. The position of benzoyl in quinoline ring is important in inhibition of MRP2. Generally, MRP2 inhibition activity of compound 7d was less in comparison to that of 6d, indicating that carboxyl group in position 4 of quinoline may interact with MRP2.

Targeted efflux transporter inhibitors - A solution to improve poor cellular accumulation of anti-cancer agents

Efflux transporters function as vacuum cleaners of xenobiotics and therefore they hinder drugs to reach their targets at effective enough concentrations. Efflux pump inhibitors can be used to improve the cell accumulation of drugs, however all the current inhibitors lack selectivity towards cancer cells. l-Type amino acid transporter 1 (LAT1), which is expressed in many types of cancer cells can be utilized to target inhibitors of efflux transporters to these cells by converting the inhibitors into LAT1-utilizing prodrugs. In this study, we prepared 5 LAT1-utilizing prodrugs of an efflux pump inhibitor, probenecid (PRB). All novel compounds were transported into human breast cancer cells (MCF-7) mainly via LAT1. The compounds also interacted with either multiresistant proteins (MRPs), P-glycoprotein (P-gp) or breast cancer resistant protein (BCRP) and increased significantly (3-4-fold) the cellular accumulation of anti-cancer agent vinblastine (VBL). Consequently, this improved the anti-proliferative efficacy of VBL by decreasing the cell growth after 72 h from 100% (VBL treatment alone) to 48-75% (combination treatment). However, the same phenomenon was not seen with other chemotherapeutic, methotrexate (MTX). Therefore, the chemotherapeutics need to be selected carefully based on their uptake mechanism to the combinations with LAT1-utilizing prodrugs of efflux pump inhibitors to defeat effectively the multidrug resistance (MDR) of chemotherapy.