3,5-Dinitrobenzylsulfanyl tetrazoles and 1,3,4-oxadiazoles, previously identified as having high in vitro activities against both replicating and nonreplicating mycobacteria and favorable cytotoxicity and genotoxicity profiles were investigated. First we demonstrated that these compounds act in a deazaflavin-dependent nitroreduction pathway and thus require a nitro group for their activity. Second, we confirmed the necessity of both nitro groups for antimycobacterial activity through extensive structure-activity relationship studies using 32 structural types of analogues, each in a five-membered series. Only the analogues with shifted nitro groups, namely, 2,5-dinitrobenzylsulfanyl oxadiazoles and tetrazoles, maintained high antimycobacterial activity but in this case mainly as a result of DprE1 inhibition. However, these analogues also showed increased toxicity to the mammalian cell line. Thus, both nitro groups in 3,5-dinitrobenzylsulfanyl-containing antimycobacterial agents remain essential for their high efficacy, and further efforts should be directed at finding ways to address the possible toxicity and solubility issues, for example, by targeted delivery.
- MeSH
- antituberkulotika farmakologie chemie MeSH
- mikrobiální testy citlivosti MeSH
- Mycobacterium tuberculosis * MeSH
- nitroreduktasy MeSH
- oxadiazoly farmakologie chemie MeSH
- savci MeSH
- tetrazoly farmakologie chemie MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Physiology-based pharmacokinetic modeling suggests that rifabutin can out-balance P-glycoprotein (P-gp) induction by concurrent P-gp inhibition. However, clinical or experimental evidence for this Janus-faced rifabutin effect is missing. Consequently, LS180 cells were exposed to a moderately (2 μM) and strongly (10 μM) P-gp-inducing concentration of rifampicin or rifabutin for 6 days. Cellular accumulation of the fluorescent P-gp substrate rhodamine 123 was evaluated using flow cytometry, either without (induction only) or with adding rifamycin drug to the cells during the rhodamine 123 efflux phase (induction + potential inhibition). Rhodamine 123 accumulation was decreased similarly by both drugs after 6-day exposure (2 μM: 55% residual fluorescence compared to non-induced cells, P < 0.01; 10 μM: 30% residual fluorescence compared to non-induced cells, P < 0.001), indicating P-gp induction. Rhodamine 123 influx transporters mRNA expressions were not affected, excluding off-target effects. Acute re-exposure to rifabutin, however, considerably re-increased rhodamine 123 accumulation (2 μM induction: re-increase by 55%, P < 0.01; 10 μM induction: 49% re-increase, P < 0.001), suggesting P-gp inhibition. In contrast, rifampicin only had weak effects (2 μM induction: no re-increase; 10 μM induction: 16% re-increase; P < 0.05). Molecular docking analysis eventually revealed that rifabutin has a higher binding affinity to the inhibitor binding site of P-gp than rifampicin (ΔG (kcal/mol) = -11.5 vs -5.3). Together, this study demonstrates that rifabutin can at least partly mask P-gp induction by P-gp inhibition, mediated by high affinity binding to the inhibitory site of P-gp.
Although some clinical studies have reported increased mitochondrial respiration in patients with fatty liver and early non‐alcoholic steatohepatitis (NASH), there is a lack of in vitro models of non‐alcoholic fatty liver disease (NAFLD) with similar findings. Despite being the most commonly used immortalized cell line for in vitro models of NAFLD, HepG2 cells exposed to free fatty acids (FFAs) exhibit a decreased mitochondrial respiration. On the other hand, the use of HepaRG cells to study mitochondrial respiratory changes following exposure to FFAs has not yet been fully explored. Therefore, the present study aimed to assess cellular energy metabolism, particularly mitochondrial respiration, and lipotoxicity in FFA‐treated HepaRG and HepG2 cells. HepaRG and HepG2 cells were exposed to FFAs, followed by comparative analyses that examained cellular metabolism, mitochondrial respiratory enzyme activities, mitochondrial morphology, lipotoxicity, the mRNA expression of selected genes and triacylglycerol (TAG) accumulation. FFAs stimulated mitochondrial respiration and glycolysis in HepaRG cells, but not in HepG2 cells. Stimulated complex I, II‐driven respiration and β‐oxidation were linked to increased complex I and II activities in FFA‐treated HepaRG cells, but not in FFA‐treated HepG2 cells. Exposure to FFAs disrupted mitochondrial morphology in both HepaRG and HepG2 cells. Lipotoxicity was induced to a greater extent in FFA‐treated HepaRG cells than in FFA‐treated HepG2 cells. TAG accumulation was less prominent in HepaRG cells than in HepG2 cells. On the whole, the present study demonstrates that stimulated mitochondrial respiration is associated with lipotoxicity in FFA‐treated HepaRG cells, but not in FFA‐treated HepG2 cells. These findings suggest that HepaRG cells are more suitable for assessing mitochondrial respiratory adaptations in the developed in vitro model of early‐stage NASH.
- MeSH
- buněčné linie MeSH
- buňky Hep G2 MeSH
- dýchání MeSH
- kyseliny mastné neesterifikované MeSH
- lidé MeSH
- mitochondrie MeSH
- nealkoholová steatóza jater * MeSH
- triglyceridy MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
As a promiscuous xenobiotic sensor, pregnane X receptor (PXR) plays a crucial role in drug metabolism. Since dietary phytochemicals exhibit the potential to modulate human PXR, this review aims to summarize the plant-derived PXR modulators, including agonists, partial agonists, and antagonists. The crystal structures of the apo and ligand-bound forms of PXR especially that of PXR complexed with binary mixtures are summarized, in order to provide the structural basis for PXR binding promiscuity and synergistic activation of PXR by composite ligands. Furthermore, this review summarizes the characterized agonists, partial agonists, and antagonists of human PXR from botanical source. Contrary to PXR agonists, there are only a few antagonists obtained from botanical source due to the promiscuity of PXR. It is worth noting that trans-resveratrol and a series of methylindoles have been identified as partial agonists of PXR, both in activating PXR function, but also inhibiting the effect of other PXR agonists. Since antagonizing PXR function plays a crucial role in the prevention of drug-drug interactions and improvement of therapeutic efficacy, further research is necessary to screen more plant-derived PXR antagonists in the future. In summary, this review may contribute to understanding the roles of phytochemicals in food-drug and herb-drug interactions.
- MeSH
- fytonutrienty farmakologie MeSH
- lidé MeSH
- pregnanový X receptor MeSH
- resveratrol MeSH
- steroidní receptory * chemie metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Following the discovery of 2-(3-methoxyphenyl)-3,4-dihydroquinazoline-4-one and 2-(3-methoxyphenyl)quinazoline-4-thione as potent, but non-specific activators of the human Constitutive Androstane Receptor (CAR, NR1I3), a series of quinazolinones substituted at the C2 phenyl ring was prepared to examine their ability to selectively modulate human CAR activity. Employing cellular and in vitro TR-FRET assays with wild-type CAR or its variant 3 (CAR3) ligand binding domains (LBD), several novel partial human CAR agonists and antagonists were identified. 2-(3-Methylphenyl) quinazolinone derivatives 7d and 8d acted as partial agonists with the recombinant CAR LBD, the former in nanomolar units (EC50 = 0.055 μM and 10.6 μM, respectively). Moreover, 7d did not activate PXR, and did not show any signs of cytotoxicity. On the other hand, 2-(4-bromophenyl)quinazoline-4-thione 7l possessed significant CAR antagonistic activity, although the compound displayed no agonistic or inverse agonistic activities. A compound possessing purely antagonistic effect was thus identified for the first time. These and related compounds may serve as a remedy in xenobiotic intoxication or, conversely, in suppression of undesirable hepatic CAR activation.
- Publikační typ
- abstrakt z konference MeSH
- Publikační typ
- abstrakt z konference MeSH
The nuclear constitutive androstane receptor (CAR, NR1I3) plays significant roles in many hepatic functions, such as fatty acid oxidation, biotransformation, liver regeneration, as well as clearance of steroid hormones, cholesterol, and bilirubin. CAR has been proposed as a hypothetical target receptor for metabolic or liver disease therapy. Currently known prototype high-affinity human CAR agonists such as CITCO (6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde-O-(3,4-dichlorobenzyl)oxime) have limited selectivity, activating the pregnane X receptor (PXR) receptor, a related receptor of the NR1I subfamily. We have discovered several derivatives of 3-(1H-1,2,3-triazol-4-yl)imidazo[1,2-a]pyridine that directly activate human CAR in nanomolar concentrations. While compound 39 regulates CAR target genes in humanized CAR mice as well as human hepatocytes, it does not activate other nuclear receptors and is nontoxic in cellular and genotoxic assays as well as in rodent toxicity studies. Our findings concerning potent human CAR agonists with in vivo activity reinforce the role of CAR as a possible therapeutic target.
- MeSH
- hepatocyty účinky léků metabolismus MeSH
- konstitutivní androstanový receptor * agonisté chemie MeSH
- lidé MeSH
- myši MeSH
- pyridiny farmakologie MeSH
- receptory cytoplazmatické a nukleární metabolismus MeSH
- steroidní receptory * agonisté chemie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Carvedilol is a widely used beta-adrenoreceptor antagonist for multiple cardiovascular indications; however, it may induce cholestasis in patients, but the mechanism for this effect is unclear. Carvedilol also prevents the development of various forms of experimental liver injury, but its effect on nonalcoholic steatohepatitis (NASH) is largely unknown. In this study, we determined the effect of carvedilol (10 mg/kg/day p.o.) on bile formation and bile acid (BA) turnover in male C57BL/6 mice consuming either a chow diet or a western-type NASH-inducing diet. BAs were profiled by liquid chromatography-mass spectrometry and BA-related enzymes, transporters, and regulators were evaluated by western blot analysis and qRT-PCR. In chow diet-fed mice, carvedilol increased plasma concentrations of BAs resulting from reduced BA uptake to hepatocytes via Ntcp transporter downregulation. Inhibition of the β-adrenoreceptor-cAMP-Epac1-Ntcp pathway by carvedilol may be the post-transcriptional mechanism underlying this effect. In contrast, carvedilol did not worsen the deterioration of BA homeostasis accompanying NASH; however, it shifted the spectra of BAs toward more hydrophilic and less toxic α-muricholic and hyocholic acids. This positive effect of carvedilol was associated with a significant attenuation of liver steatosis, inflammation, and fibrosis in NASH mice. In conclusion, our results indicate that carvedilol may increase BAs in plasma by modifying their liver transport. In addition, carvedilol provided significant hepatoprotection in a NASH murine model without worsening BA accumulation. These data suggest beneficial effects of carvedilol in patients at high risk for developing NASH.
- MeSH
- homeostáza MeSH
- játra MeSH
- karvedilol farmakologie metabolismus MeSH
- lidé MeSH
- membránové transportní proteiny metabolismus MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- nealkoholová steatóza jater * metabolismus MeSH
- žlučové kyseliny a soli metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
