Pharmacophore combination as a useful strategy to discover new antitubercular agents

The present study is aimed at combining two well-known pharmacophores (pyrazoline and benzoxazole nucleus) to design and synthesize a series of substituted pyrazoline-based benzoxazole derivatives. In vitro antitubercular evaluation against Mycobacterium tuberculosis H37Rv, multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) strains showed that most of the target compounds displayed potent activity (MIC ~1.25–25 μg/mL) where few compounds were found to be better than isoniazid against MDR-TB (MIC = 3.25 μg/mL) and XDR-TB (MIC = 12.5 μg/mL). Cytotoxicity assay of these active compounds in VERO cell lines displayed good selectivity index. In order to gain insights into the plausible binding motifs, the target compounds were docked into enoyl-acyl carrier protein reductase, a molecular target of isoniazid. All the docked compounds occupied the same hydrophobic binding pocket and interacted mostly by dispersion interactions. Contribution of the three pharmacophoric fragments (pyrazoline, benzoxazole and aryl ring) toward protein–ligand binding was evaluated at semi empirical quantum mechanics level. The interaction energies suggested that most of the binding was governed by the benzoxaxole moiety followed by pyrazoline and aryl rings.     

Modeling of Bounded Outcome Scores with Data on the Boundaries: Application to Disability Assessment for Dementia Scores in Alzheimer’s Disease

Mixed-effects beta regression (BR), boundary-inflated beta regression (ZOI), and coarsening model (CO) were investigated for analyzing bounded outcome scores with data at the boundaries in the context of Alzheimer’s disease. Monte Carlo simulations were conducted to simulate disability assessment for dementia (DAD) scores using these three models, and each set of simulated data were analyzed by the original simulation model. One thousand trials were simulated, and each trial contained 250 subjects. For each subject, DAD scores were simulated at baseline, 13, 26, 39, 52, 65, and 78 weeks. The simulation-reestimation exercise showed that all the three models could reasonably recover their true parameter values. The bias of the parameter estimates of the ZOI model was generally less than 1%, while the bias of the CO model was mainly within 5%. The bias of the BR model was slightly higher, i.e., less than or in the order of 20%. In the application to real-world DAD data from clinical studies, examination of prediction error and visual predictive check (VPC) plots suggested that both BR and ZOI models had similar predictive performance and described the longitudinal progression of DAD slightly better than the CO model. In conclusion, the investigated three modeling approaches may be sensible choices for bounded outcome scores with data on the edges. Prediction error and VPC plots can be used to identify the model with best predictive performance.     

Sodium chloride or plasmalyte-148 for patients presenting to emergency departments with diabetic ketoacidosis: A nested cohort study within a multicentre,cluster, crossover,randomised, controlled trial

Objective

To test the hypothesis that fluid resuscitation in the ED with plasmalyte-148 (PL) compared with 0.9% sodium chloride (SC) would result in a lower proportion of patients with diabetic ketoacidosis (DKA) requiring intensive care unit (ICU) admission.

Methods

We performed a prespecified nested cohort study at two hospitals within a cluster, crossover, open label, randomised, controlled trial comparing the effects of PL versus SC as fluid therapy for patients who presented to the ED with DKA. All patients presenting within a fixed recruitment period were included. The primary outcome was the proportion of patients admitted to ICU.

Results

Eighty-four patients were enrolled (SC n = 38, PL n = 46). The SC group had a lower median pH on admission (SC: 7.09 [interquartile range (IQR) 7.01–7.21], PL: 7.17 [IQR 6.99–7.26]). The median volume of intravenous fluids administered in ED was 2150 mL (IQR 2000–3200 mL; SC) and 2200 mL (IQR 2000–3450; PL); respectively. A higher proportion of patients in the SC group, 19 (50%), was admitted to ICU compared with PL group, 18 (39.1%); however, after adjustment for pH at presentation and diabetes type in a multivariable logistic regression model, the PL group did not have a significantly different rate of ICU admission compared with the SC group (odds ratio for ICU admission 0.73, 95% confidence interval 0.13–3.97, P = 0.71).

Conclusion

Patients with DKA treated with PL compared with SC in the EDs had similar rates of requiring ICU admission.     

Naringin ameliorates gentamicin-induced nephrotoxicity and associated mitochondrial dysfunction,apoptosis and inflammation in rats: Possible mechanism of nephroprotection

Gentamicin-induced nephrotoxicity has been well documented, although its underlying mechanisms and preventive strategies remain to be investigated. The present study was designed to investigate the protective effect of naringin, a bioflavonoid, on gentamicin-induced nephrotoxicity and to elucidate the potential mechanism. Serum specific renal function parameters (blood urea nitrogen and creatinine) and histopathology of kidney tissues were evaluated to assess the gentamicin-induced nephrotoxicity. Renal oxidative stress (lipid peroxidation, protein carbonylation, enzymatic and non-enzymatic antioxidants), inflammatory (NF-kB [p65], TNF-α, IL-6 and MPO) and apoptotic (caspase 3, caspase 9, Bax, Bcl-2, p53 and DNA fragmentation) markers were also evaluated. Significant decrease in mitochondrial NADH dehydrogenase, succinate dehydrogenase, cytochrome c oxidase and mitochondrial redox activity indicated the gentamicin-induced mitochondrial dysfunction. Naringin (100 mg/kg) treatment along with gentamicin restored the mitochondrial function and increased the renal endogenous antioxidant status. Gentamicin induced increased renal inflammatory cytokines (TNF-α and IL-6), nuclear protein expression of NF-κB (p65) and NF-κB-DNA binding activity and myeloperoxidase (MPO) activity were significantly decreased upon naringin treatment. In addition, naringin treatment significantly decreased the amount of cleaved caspase 3, Bax, and p53 protein expression and increased the Bcl-2 protein expression. Naringin treatment also ameliorated the extent of histologic injury and reduced inflammatory infiltration in renal tubules. U-HPLS-MS data revealed that naringin co-administration along with gentamicin did not alter the renal uptake and/or accumulation of gentamicin in kidney tissues. These findings suggest that naringin treatment attenuates renal dysfunction and structural damage through the reduction of oxidative stress, mitochondrial dysfunction, inflammation and apoptosis in the kidney.     

Anti-anxiety effect of a novel 5-HT3 receptor antagonist N-(benzo[d]thiazol-2-yl)-3-ethoxyquinoxalin-2-carboxamide (6k) using battery tests for anxiety in mice

Objective:

To investigate the anti-anxiety activity of “6k”, a novel 5-hydroxytryptamine type 3 (5-HT₃) receptor antagonist in in mice.

Materials and Methods:

Anti-anxiety activity of “6k” (1, 2, and 4 mg/kg, intraperitoneally (i.p.)) was evaluated in mice by behavioral tests such as elevated plus maze (EPM), open field test (OFT), light-dark box (L&D), and hole board test (HBT). Diazepam (2 mg/kg, i.p.) served as reference standard.

Results:

“6k” significantly (P < 0.05) increased the time and entries in open arm in EPM as compared to vehicle control group. Further, “6k” significantly (P < 0.05) increased the central and peripheral ambulation along with rearings and time in central area; whereas, reduced the fecal pellets in OFT as compared to vehicle control group. There was significant (P < 0.05) reduction in the latency to enter dark chamber; whereas, increased number of crossings and time in light chamber in L&D aversion test by treatment with “6k” as compared to vehicle control group. In HBT, “6k” significantly (P < 0.05) increased the number of head dipping and squares crossed; whereas, reduced the latency for first head dip and number of fecal pellets as compared to vehicle control group.

Conclusion:

A novel 5-HT₃ receptor antagonist has anti-anxiety action.KEY WORDS: 5-HT₃ antagonist, anxiety, elevated plus maze, open field test, hole board test     

Neuropharmacological evaluation of a novel 5-HT3 receptor antagonist (6g) on chronic unpredictable mild stress-induced changes in behavioural and brain oxidative stress parameters in mice

Aim:

The aim of the study was to evaluate a novel 5 HT₃ receptor antagonist (6g) on chronic stress induced changes in behavioural and brain oxidative stress parameter in mice. A complicated relationship exists among stressful stimuli, body''s reaction to stress and the onset of clinical depression. Chronic unpredictable stressors can produce a situation similar to human depression, and such animal models can be used for the preclinical evaluation of antidepressants.

Materials and Methods:

In the present study, a novel and potential 5-HT₃ receptor antagonist (4-benzylpiperazin-1-yl)(3-methoxyquinoxalin-2-yl) methanone (6g) with good Log P (3.08) value and pA₂(7.5) values, synthesized in our laboratory was investigated to study the effects on chronic unpredictable mild stress (CUMS)-induced behavioural and biochemical alterations in mice. Mice were subjected to different stress paradigms daily for a period of 28 days to induce depressive-like behaviour.

Results:

The results showed that CUMS caused depression-like behaviour in mice, as indicated by the significant (P < 0.05) decrease in sucrose consumption and locomotor activity and increase in immobility the forced swim test. In addition, it was found that lipid peroxidation and nitrite levels were significantly (P < 0.05) increased, whereas glutathione levels, superoxide dismutase and catalase activities decreased in brain tissue of CUMS-treated mice. ‘6g’ (1 and 2 mg/kg, p.o., 21 days) and fluoxetine treatment (20 mg/kg, p.o., 21 days) significantly (P < 0.05) reversed the CUMS-induced behavioural (increased immobility period, reduced sucrose preference and decreased locomotor activity) and biochemical (increased lipid peroxidation; decreased glutathione levels, superoxide dismutase and catalase activities). However fluoxetine treatment (20 mg/kg, p.o., 21 days) significantly decreased the nitrite level in the brain while ‘6g’ (1 and 2 mg/kg, p.o., 21 days) did not show significant (P < 0.05) effect on the nitrite levels in brain.

Conclusion:

Compound ‘6g’ exerted antidepressant-like effects in behavioural despair paradigm in chronically stressed mice by restoring antioxidant mechanisms.KEY WORDS: 5-HT₃ receptor antagonist, chronic unpredictable mild stress, depression, oxidative stress     

Estimating Endogenous Dopamine Levels at D2 and D3 Receptors in Humans using the Agonist Radiotracer [11C]-(+)-PHNO

Using positron emission tomography (PET) and an acute dopamine depletion challenge it is possible to estimate endogenous dopamine levels occupying dopamine D_2/3 receptors (D_2/3R) in humans in vivo. Our group has developed [¹¹C]-(+)-PHNO, the first agonist radiotracer with preferential in vivo affinity for D₃R. Thus, the use of [¹¹C]-(+)-PHNO offers the novel possibility of (i) estimating in vivo endogenous dopamine levels at D_2/3R using an agonist radiotracer, and (ii) estimating endogenous dopamine levels at D₃R in extrastriatal regions such as the substantia nigra, hypothalamus, and ventral pallidum. Ten healthy participants underwent a [¹¹C]-(+)-PHNO PET scan under baseline conditions and another under acute endogenous dopamine depletion achieved via oral administration of alpha-methyl-para-tyrosine (64 mg/kg). [¹¹C]-(+)-PHNO binding was sensitive to acute dopamine depletion, allowing in vivo estimates of endogenous dopamine in D₂R-rich regions (caudate and putamen), mixed D_2/3R-rich regions (ventral striatum and globus pallidus), and extrastriatal D₃R-rich regions (hypothalamus and ventral pallidum). Dopamine depletion decreased self-reported vigor, which was correlated with the reduction in dopamine levels in the globus pallidus. [¹¹C]-(+)-PHNO is a suitable radiotracer for use in estimating endogenous dopamine levels at D₂R and D₃R in neuropsychiatric populations.