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•Mechanism of metronidazole neurotoxicity has been illustrated.•Pharmacodynamic interaction of quercetin and metronidazole has been investigated.•Quercetin show protection against ...metronidazole neuronal toxicity and neuroinflammation.
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.
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.
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.
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.
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•Various bioanalytical method validation guidelines have been issued worldwide by different regulatory agencies.•This review provides summary to evaluate the different guidelines ...during bioanalytical method development and validation.•Different evaluation parameters such as matrix effect, incurred sample reanalysis and various stability aspects with an easy way for designing the bioanalytical method validation have been discussed.
The concepts, importance, and application of bioanalytical method validation have been discussed for a long time and validation of bioanalytical methods is widely accepted as pivotal before they are taken into routine use. United States Food and Drug Administration (USFDA) guidelines issued in 2001 have been referred for every guideline released ever since; may it be European Medical Agency (EMA) Europe, National Health Surveillance Agency (ANVISA) Brazil, Ministry of Health and Labour Welfare (MHLW) Japan or any other guideline in reference to bioanalytical method validation. After 12 years, USFDA released its new draft guideline for comments in 2013, which covers the latest parameters or topics encountered in bioanalytical method validation and approached towards the harmonization of bioanalytical method validation across the globe. Even though the regulatory agencies have general agreement, significant variations exist in acceptance criteria and methodology. The present review highlights the variations, similarities and comparison between bioanalytical method validation guidelines issued by major regulatory authorities worldwide. Additionally, other evaluation parameters such as matrix effect, incurred sample reanalysis including other stability aspects have been discussed to provide an ease of access for designing a bioanalytical method and its validation complying with the majority of drug authority guidelines.
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•Curcumin mimic–1,2,3-triazole conjugates with two prototypes were synthesized.•Compounds 17 and 26 displayed significant anticancer activity than curcumin.•Compounds 17 and 26 ...induced mitochondrial-mediated apoptosis and cell cycle arrest.•Also significantly down regulated phospho-Akt, PCNA, Bcl-2 and upregulated Bax.
The anti-cancer property of curcumin, an active component of turmeric, is limited due to its poor solubility, stability and bioavailability. To enhance its efficacy, we designed a novel series of twenty-four monocarbonyl curcumin analogue–1,2,3-triazole conjugates and evaluated their anti-cancer activity towards endocrine related cancers. The new compounds (17–40) were synthesized through CuAAC click reaction and SAR analysis carried out. Out of these all, compound 17 showed most significant anti-cancer activity against prostate cancer cells with IC50 values of 8.8μM and 9.5μM in PC-3 and DU-145 cells, respectively. Another compound 26 showed significant anti-cancer activity against breast cancer cells with IC50 of 6μM, 10μM and 6.4μM in MCF-7, MDA-MB-231 and 4T1 cells, respectively while maintaining low toxicity towards non-cancer originated cell line, HEK-293. Compounds 17 and 26 arrested cell cycle and induced mitochondria-mediated apoptosis in cancer cells. Further, both of these compounds significantly down-regulated cell proliferation marker (PCNA), inhibited activation of cell survival protein (Akt phosphorylation), upregulated pro-apoptotic protein (Bax) and down-regulated anti-apoptotic protein (Bcl-2) in their respective cell lines. In addition, in vitro stability, solubility and plasma binding studies of the compounds 17 and 26 showed them to be metabolically stable. Thus, this study identified two new curcumin monocarbonyl–1,2,3-triazole conjugate compounds with more potent activity than curcumin against breast and prostate cancers.
Pentoxifylline (PTX) is a non-selective phosphodiesterase inhibitor and is used for the management of intermittent claudication. We tested whether PTX has oral efficacy in stimulating new bone ...formation. Rat calvarial osteoblasts (RCO) were used to study the effect of PTX on osteoblast differentiation and angiogenesis. Pharmacokinetic and pharmacodynamic studies were carried out in rats to determine an oral dose of PTX. In ovariectomized (OVX) rats with osteopenia, the effect of PTX on various skeletal parameters was studied, and compared with teriparatide. Effect of PTX on angiogenic signaling was studied by immunoblotting and relevant pharmacologic inhibitors. Bone vascularity was measured by intravenous injection of polystyrene fluorospheres followed by in vivo imaging, and angiogenesis was studied in vitro by tubulogenesis of endothelial cells and in vivo by Matrigel plug assay. Effective concentration (EC
50
) of PTX in RCO was 8.2 nM and plasma PTX level was 7 nM/mL after single oral dosing of 25 mg/kg, which was 1/6th the clinically used dose. At this dose, PTX enhanced bone regeneration at femur osteotomy site and completely restored bone mass, microarchitecture, and strength in OVX rats. Furthermore, PTX increased surface referent bone formation parameters and serum bone formation marker (PINP) without affecting the resorption marker (CTX-1). PTX increased the expression of vascular endothelial growth factor and its receptor in bones and osteoblasts. PTX also increased skeletal vascularity, tubulogenesis of endothelial cells and in vivo angiogenesis. Taken together, our study suggested that PTX at 16% of adult human oral dose completely reversed osteopenia in OVX rats by osteogenic and osteo-angiogenic mechanisms.
Bioavailability, one of the prime pharmacokinetic properties of a drug, is defined as the fraction of an administered dose of unchanged drug that reaches the systemic circulation and is used to ...describe the systemic availability of a drug. Bioavailability assessment is imperative in order to demonstrate whether the drug attains the desirable systemic exposure for effective therapy. In recent years, bioavailability has become the subject of importance in drug discovery and development studies.
A systematic literature review in the field of bioavailability and the approaches towards its enhancement have been comprehensively done, purely focusing upon recent papers. The data mining was performed using databases like PubMed, Science Direct and general Google searches and the collected data was exhaustively studied and summarized in a generalized manner.
The main prospect of this review was to generate a comprehensive one-stop summary of the numerous available approaches and their pharmaceutical applications in improving the stability concerns, physicochemical and mechanical properties of the poorly water-soluble drugs which directly or indirectly augment their bioavailability.
The use of novel methods, including but not limited to, nano-based formulations, bio-enhancers, solid dispersions, lipid-and polymer-based formulations which provide a wide range of applications not only increases the solubility and permeability of the poorly bioavailable drugs but also improves their stability, and targeting efficacy. Although, these methods have drastically changed the pharmaceutical industry demand for the newer potential methods with better outcomes in the field of pharmaceutical science to formulate various dosage forms with adequate systemic availability and improved patient compliance, further research is required.
Malaria is a major life-threatening tropical disease affecting about half of the world’s population. Due to the increasing resistance of
Plasmodium falciparum
against the marketed drugs, the ...non-endemic areas of malaria are also at risk which demands for continuous and a compelling need to investigate the bioactive natural products for their pharmacological activity against malaria parasite and undoubtedly satisfactory outcomes are being observed with less adverse events in such endeavours. Flavonoids have emerged as the most important bio-therapeutic class possessing anti-malarial activity. Flavonoids have also been reported to reverse anti-malarial drug resistance, thus exerting dual therapeutic benefit. The pharmacological outcome of these bioactive constituents essentially depends on their circulating levels reaching the target site of action thus, necessitating the quantification in bio-matrices which is required for personalized therapy. Furthermore, the estimation of drug level in biological system is crucial for therapeutic drug monitoring. The development and validation of high-throughput bio-analytical methods for estimation of phytochemicals in biological fluids is a preliminary requirement for establishing such PK–PD relationship. The present review intends to shed an insightful focus on the available bio-analytical methods for assessment of natural anti-malarial flavonoids which will be of immense help in their further exploration.
Isoformononetin (methoxy isoflavone) is a potent osteogenic isoflavone abundantly present in Butea monosperma, Pisum sativum, Mung bean, Machaerium villosum, Medicago sativa, and Glycine max. In the ...current study, an LC–ESI-MS/MS method for the simultaneous evaluation of isoformononetin (IFN), daidzein (DZN) and equol (EQL) was developed and validated in rat plasma using biochanin A as an internal standard. IFN, DZN, and EQL separation was achieved by using acetonitrile and acetic acid (0.1%) in the ratio of 90:10 (% v/v) as mobile phase under isocratic conditions at a flow rate of 0.6 mL/min on Atlantis C18 (4.6 × 250 mm, 5.0 μm) column. The achieved method was linear within the concentration range of 0.5–500 ng/mL. The method was effectively applied to investigate the permeability, protein binding estimation and pharmacokinetics studies of IFN in rats. The PAMPA permeability of IFN was found to be high at pH 4.0 and 7.0. The protein binding was found to be about 91% of IFN. The oral bioavailability of IFN was found to be poor (21.6%). IFN was found to have a moderate clearance (2.9 L/h/kg) and a large apparent volume of distribution (12.1 L/kg). The plasma half-life (t1/2) and maximum attainable concentration (Cmax) of IFN at systemic circulation was found to be 1.9 ± 0.6 h and 269.3 ± 0.4 after oral administration.
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•A rapid simultaneous LC-MS/MS method of isoformononetin, daidzein and equol in rat plasma was developed.•The method was sensitive with 0.5 ng/mL as lower limit of quantification for all analytes.•Comprehensive preclinical in vitro and in vivo pharmacokinetics and permeability studies were investigated for first time.•Absolute bioavailability of isoformononetin was low (21.6%).
Abstract
Withanolides are the group of active chemical constituents of Withania somnifera (L.) Dunal. Withaferin A, withanolide A and withanone presents three of the biologically most active ...constituents of this herb. These steroidal lactones are isomers of each other and thus, pose significant difficulty in their separation. In present study, a simple, specific and reliable RP-HPLC method has been developed and validated for their separation and simultaneous quantification. Separation was carried out on Lichrocart Purospher STAR RP-18e column (250 × 4.5 mm, 5 µm) using mobile phase, methanol and 0.01 M ammonium acetate buffer (pH 5) in the ratio 60:40, v/v. The calibration curves were linear (r
2 > 0.99) for all the three compounds across concentration range of 1.56–50 µg/mL. The lower limit of quantification for all the analytes was 1.56 µg/mL. The intra-day and inter-day accuracy was between 88.65% and 110.66% and coefficient of variation was between 0.55 and 10.12. The analytes were stable under different storage conditions. The developed method was successfully applied to analyze the samples for simultaneous determination of permeability of the three withanolides in rats using in situ single-pass intestinal perfusion model. Withanolide A and withanone were found to be high permeability compounds while withaferin A could not be detected.
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.
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.
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.
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.
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Enterohepatic recirculation (EHC) concerns many physiological processes and notably affects pharmacokinetic parameters such as plasma half-life and AUC as well as estimates of bioavailability of ...drugs. Also, EHC plays a detrimental role as the compounds/drugs are allowed to recycle. An in-depth comprehension of this phenomenon and its consequences on the pharmacological effects of affected drugs is important and decisive in the design and development of new candidate drugs. EHC of a compound/drug occurs by biliary excretion and intestinal reabsorption, sometimes with hepatic conjugation and intestinal deconjugation. EHC leads to prolonged elimination half-life of the drugs, altered pharmacokinetics and pharmacodynamics. Study of the EHC of any drug is complicated due to unavailability of the apposite model, sophisticated procedures and ethical concerns. Different in vitro and in vivo methods for studies in experimental animals and humans have been devised, each having its own merits and demerits. Involvement of the different transporters in biliary excretion, intra- and inter-species, pathological and biochemical variabilities obscure the study of the phenomenon. Modeling of drugs undergoing EHC has always been intricate and exigent models have been exploited to interpret the pharmacokinetic profiles of drugs witnessing multiple peaks due to EHC. Here, we critically appraise the mechanisms of bile formation, factors affecting biliary drug elimination, methods to estimate biliary excretion of drugs, EHC, multiple peak phenomenon and its modeling.
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