Mechanistic exploration of quercetin against metronidazole induced neurotoxicity in rats: Possible role of nitric oxide isoforms and inflammatory cytokines.

AIM: Metronidazole, a nitroimidazole derived antibiotic used to treat many bacterial infections, is reported to penetrate the blood brain barrier after long term administration resulting into neuronal toxicity. Further, quercetin, a polyphenol flavonoid is reported to exhibit neuroprotective activity but its pharmacodynamics interaction against metronidazole induced neurotoxicity. Therefore, the present study was designed to evaluate the postulated mechanism of metronidazole induced neurotoxicity and potential neuroprotective role of quercetin. MAIN METHODS: Animals (Sprague Dawley) rats were randomly divided into five groups such as control, metronidazole (135 mg/kg), quercetin (100 mg/kg), metronidazole (135 mg/kg) + quercetin (50 mg/kg), and metronidazole (135 mg/kg) + quercetin (100 mg/kg). The brain tissues were evaluated for tissue cyclo-oxygenase, lipoxygenase, nitrite levels, inflammatory and antioxidant biomarkers. The brain tissues were further scrutinized histopathologically for neuronal degeneration. Western blotting analysis was performed for the localization of protein expression for Bax, Bcl2, iNOS, eNOS and caspase-3. KEY FINDINGS: The metronidazole significantly alters the antioxidant levels, inflammatory mediators and morphological changes in the brain tissue. Metronidazole also induces iNOS, Bax and caspase 3 protein expressions whilst decreases the expression of Bcl2 and eNOS in the brain tissue. Metronidazole administration causes a momentous increase in tissue inflammatory markers. SIGNIFICANCE: The metronidazole (oral) administration causes remarkably neurotoxicity effects and the same could be attributed to the fact that metronidazole has the ability to cross the blood brain barrier and transforms the enzymatic activity of various biomarkers present in the brain. From the results, it could be hypothesized that metronidazole causes neurotoxicity by hindering the proportion of antioxidants in the brain tissue and inducing nitric oxide synthesis along with apoptosis. However, quercetin demonstrated a significant protective effect on neuronal toxicity precipitated through metronidazole.

Formononetin and biochanin A protects against ritonavir induced hepatotoxicity via modulation of NfκB/pAkt signaling molecules.

AIMS: Ritonavir (RIT) is a human immune deficiency virus (HIV) protease inhibitor (PI) active against HIV-1 and HIV-2. Among various adverse effects of PIs, hepatotoxicity is a very common adverse reaction of RIT which is concentration dependent. Red clover isoflavones are found to possess anti-inflammatory, antioxidant and anti-apoptosis activity. Furthermore, recent studies have demonstrated that these isoflavones can be used to alleviate the side-effects of drugs. Hence, the present study was inquested to ascertain the effect of Formononetin (FMN) and Biochanin A (BCA) on RIT induced hepatotoxicity. MAIN METHODS: Five groups of animals were subjected to treatment as control, toxic control (RIT), third group (RIT + FMN), fourth group (RIT + BCA), the fifth group (RIT + FMN + BCA) and sixth group (FMN + BCA) for 14 days. The animals were evaluated for estimation of liver toxicity markers, inflammatory biomarkers, in-vivo biochemical antioxidant parameters. The liver tissues were further evaluated histopathologically and western blotting examination for localization of apoptotic gene expression that plays a pivotal role in hepatotoxicity. KEY FINDINGS: FMN and BCA ameliorated the increased levels of biochemical markers of liver, attenuated the RIT induced Bax, caspase-3, NFκB and eNOS activation and persuaded the Bcl2 and pAkt level. Alteration in the levels of inflammatory markers was also observed in both hepatic tissue and serum. SIGNIFICANCE: FMN and BCA exerts hepatoprotective effect through modulating the oxidative stress, inflammation, apoptosis and reversing the tissue degeneration suggesting its therapeutic role in hepatotoxicity and other hepatocellular diseases.

Preclinical pharmacokinetics and ADME characterization of a novel anticancer chalcone, cardamonin.

Cardamonin (CRD), a chalconoid obtained from several medicinal plants of Zingiberaceae family, had shown promising potential in cancer prevention and therapy. For further development and better pharmacological elucidation, we performed a series of in vitro and in vivo studies to characterize its preclinical pharmacokinetics. The study samples were analyzed using validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) and high performance liquid chromatography-ultra violet (HPLC-UV) methods. CRD is partially soluble (<10 µM) and possess high permeability (>0.2 × 10-4 cm/sec). It is moderately bound to plasma proteins (<50%). It shows partitioning in red blood cell (RBC) compartment with the partition coefficient between RBCs and plasma (KRBC/P ) of 0.95 at 0 min to 1.39 at 60 min, indicating significant but slow RBC uptake. In mice, CRD is poorly absorbed after oral administration with 18% oral bioavailability. It possesses high clearance, short mean residence time, and high volume of distribution in mice. It exhibited multiple peak phenomena both after oral and intravenous administration and is excreted both as conjugated and unchanged CRD in bile. It is majorly excreted in faeces and negligibly in urine. The preclinical absorption, distribution, metabolism, and excretion data are expected to succour the future clinical investigations of CRD as a promising anticancer agent. Copyright © 2016 John Wiley & Sons, Ltd.

Rapid quantitative analysis of ormeloxifene and its active metabolite, 7-desmethyl ormeloxifene, in rat plasma using liquid chromatography-tandem mass spectrometry.

Ormeloxifene (ORM) is a non-steroidal, selective estrogen receptor modulator used as a once a week oral contraceptive and is intended for long-term clinical use by females. Therefore, a simple, sensitive and rapid LC-MS/MS method was developed and validated for simultaneous quantification of ORM and its active metabolite (7-desmethyl ormeloxifene, 7-DMO) in rat plasma. Also, the method was partially validated in human plasma. Chromatographic separation was achieved on Discovery HS C-18 column (5µm, 50×4.6mm) with mobile phase [acetonitrile: aqueous ammonium acetate (0.01M) buffer (85: 15, %v/v)] at a flow rate of 0.8mL/min. The calibration curve was linear (r≥0.99) for a concentration range of 0.78-100ng/mL for both the analytes. The precision (%RSD; ORM, 1.3 to 13.4; 7-DMO, 3.1 to 15.0) and accuracy (%bias; ORM, -13.8 to 12.5; 7-DMO, -10.6 to 6.8) in both rat and human plasma were within the acceptable limits. The recovery for ORM and 7-DMO was always >79.1% and >72.9%, respectively. Both the analytes were found stable in rat plasma even after 30 days of storage at -80°C and on being subjected to three freeze-thaw cycles. The method has not only short run time (3.5min) but requires a low plasma sample volume (20µL) and is the first reported LC-MS/MS method for simultaneous quantification of the marketed drug known as centchroman (INN: ormeloxifene) and the metabolite 7-DMO in plasma. The method was applied to evaluate drug-drug interaction of ORM with the commonly prescribed antidepressant drug sertraline using serial sampling in rats.