A novel dihydropyridine with 3-aryl meta-hydroxyl substitution blocks L-type calcium channels in rat cardiomyocytes

Transient receptor potential canonical type 6 (TRPC6) O-GlcNAcylation at Threonine-221 plays potent role in channel regulation

Transient receptor potential canonical type 6 (TRPC6) is a non-voltage-gated channel that principally conducts calcium. Elevated channel activation contributes to fibrosis, hypertrophy, and proteinuria, often coupled to stimulation of nuclear factor of activated T-cells (NFAT). TRPC6 is post-translationally regulated, but a role for O-linked β-N-acetyl glucosamine (O-GlcNAcylation) as elevated by diabetes, is unknown. Here we show TRPC6 is constitutively O-GlcNAcylated at Ser14, Thr70, and Thr221 in the N-terminus ankryn-4 (AR4) and linker (LH1) domains. Mutagenesis to alanine reveals T221 as a critical controller of resting TRPC6 conductance, and associated NFAT activity and pro-hypertrophic signaling. T→A mutations at sites homologous in closely related TRPC3 and TRPC7 also increases their activity. Molecular modeling predicts interactions between Thr221-O-GlcNAc and Ser199, Glu200, and Glu246, and combined alanine substitutions of the latter similarly elevates resting NFAT activity. Thus, O-GlcNAcylated T221 and interactions with coordinating residues is required for normal TRPC6 channel conductance and NFAT activation.

The nonlinear optical properties of two dihydropyridones derived from curcumin

Two dihydropyridone compounds are synthesized from curcumin using microwave radiation. Both compounds were identified by their melting points and ¹HNMR spectra. The nonlinear properties viz., nonlinear absorption coefficients and nonlinear refractive index of both compounds were calculated at wavelength 473 nm using the diffraction ring patterns and Z-scan techniques separately. The diffraction ring patterns evolved from circular symmetric to asymmetric due to convection current in the vertical direction. As a result of using Gaussian laser beam, the Fraunhofer approximation of the Fresnel-Kirchhoff diffraction, have led to successful simulation of the diffraction ring patterns with good quantitative and excellent qualitative agreements compared with experimental results. Optical limiting property has been tested in both compounds.

Formation and temporal evolution of diffraction ring patterns in a newly prepared dihydropyridone

A dihydropyridone has been prepared from butylamine and curcumin. A theoretical DFT study was conducted to determine the most stable conformer of the studied molecule (among three conformers) using the B3LYP/6-311+G(d,p) level of theory. This is assisted by the prediction of the ¹³C NMR chemical shifts of the conformers which then correlated with the observed ¹³C NMR chemical shifts. A TD-DFT study was conducted to analyze the electronic spectrum of the most stable conformer in order to determine the transitions responsible for the longer band in the electronic spectrum of the molecule. As well the frontier orbitals in the most stable conformer were analyzed to establish the density of donor and acceptor sites in the molecule that may be responsible for the nonlinear optical (NLO) properties of the studied molecule. Diffraction ring patterns were observed as a result of the use of visible, 473 nm, low power single mode laser beam traversed a thin cell containing solution of dihydropyridone. The nonlinear refractive index, n₂, was determined based on the number of diffraction rings per a pattern observed and by the Z-scan technique and both results are compared. The upward convection heat effect appears to be responsible for the asymmetries observed in the diffraction ring patterns. The use of convergent and divergent laser beams has led to new types of diffraction ring patterns. Temporal evolution of each diffraction ring patterns was registered. The diffraction ring patterns experimentally obtained are numerically calculated using the Fresnel-Kirchhoff diffraction integral, with good qualitative and reasonable quantitative agreements.

New fatty dihydropyridines present cardioprotective potential in H9c2 cardioblasts submitted to simulated ischemia and reperfusion

Nifedipine is a calcium channel blocker dihydropyridine that has been used in the treatment of hypertension. The production of reactive species and calcium overload are the main contributors to myocardial ischemia-reperfusion (I / R) injury. We investigated the ability of novel dihydropyridines (DHPs) to improve the effect of protecting against the injury induced by ischemia and reperfusion in cardioblasts when compared to nifedipine. Forty three DHPs were created varying the fatty chains derived from palmitic acid, stearic acid and oleic acids and aromatic moiety in addition to the addition of chemical elements such as chlorine, nitrogen dioxide, furfural, hydroxyl and methoxy. Cytotoxicity and inhibition of linoleic oxidation were evaluated for all new DHPs and also for nifedipine. The alpha-tocopherol and butylated hydroxytoluene (BHT) were used as antioxidants controls. The compounds with the best antioxidant potential were used in the ischemia and reperfusion (I / R) induction test in cardioblasts (H9c2). Cardioblasts were treated 24 h after assembly of plates and submitted to the ischemia simulation (30 min), after which, normoxia and cellular nutrition conditions were reestablished, simulating reperfusion (additional 30 min). Right after, cell viability, apoptosis, necrosis, and the generation of reactive oxygen species (ROS) were evaluated. Cell viability during I / R was not altered in cells treated with nifedipine, BHT and the new DHP composed of palmitic acid with hydroxyl group in the aromatic substituent. The other new DHPs increased cell viability during I / R simulation and reduced levels of reactive species compared to the I / R group, demonstrating the antioxidant capacity of the new DHPs. Therefore, DHPS with palmitic and oleic acids in the C3 and C5 position with NO2 or Cl in aromatic moiety, presented the highest antioxidant potential (linoleic oxidant test). The new DHPs increased cell viability during I / R simulation and reduced levels of reactive species compared to the ischemia and reperfusion group, demonstrating the antioxidant capacity of the new DHPs. Taken together, these results indicate that those new DHPs have a greater cardioprotective antioxidant capacity to face the damages of ischemia and reperfusion.

Protective role of the novel hybrid 3,5-dipalmitoyl-nifedipine in a cardiomyoblast culture subjected to simulated ischemia/reperfusion

This work investigated the acute effects of the calcium channel blocker nifedipine and its new fatty hybrid derived from palmitic acid, 3,5-dipalmitoyl-nifedipine, compared to endocannabinoid anandamide during the process of inducing ischemia and reperfusion in cardiomyoblast H9c2 heart cells. The cardiomyoblasts were treated in 24 or 96-well plates (according to the test being performed) and maintaining the treatment until the end of hypoxia induction. The molecules were tested at concentrations of 10 and 100μM, cells were treated 24h after assembling the experimental plates and immediately before the I/R. Cell viability, apoptosis and necrosis, and generation of reactive oxygen species were evaluated. Nifedipine and 3,5-dipalmitoyl-nifedipine were used to assess radical scavenging potential and metal chelation. All tested molecules managed to reduce the levels of reactive oxygen species compared to the starvation+vehicle group. In in vitro assays, 3,5-dipalmitoyl-nifedipine showed more antioxidant activity than nifedipine. These results indicate the ability of this molecule to act as a powerful ROS scavenger. Cell viability was highest when cells were induced to I/R by both concentrations of anandamide and the higher concentration of DPN. These treatments also reduced cell death. Therefore, it was demonstrated that the process of hybridization of nifedipine with two palmitic acid chains assigns a greater cardioprotective effect to this molecule, thereby reducing the damage caused by hypoxia and reoxygenation in cardiomyoblast cultures.

Analysis of Statistical Methods Currently used in Toxicology Journals

Statistical methods are frequently used in toxicology, yet it is not clear whether the methods employed by the studies are used consistently and conducted based on sound statistical grounds. The purpose of this paper is to describe statistical methods used in top toxicology journals. More specifically, we sampled 30 papers published in 2014 from Toxicology and Applied Pharmacology, Archives of Toxicology, and Toxicological Science and described methodologies used to provide descriptive and inferential statistics. One hundred thirteen endpoints were observed in those 30 papers, and most studies had sample size less than 10, with the median and the mode being 6 and 3 & 6, respectively. Mean (105/113, 93%) was dominantly used to measure central tendency, and standard error of the mean (64/113, 57%) and standard deviation (39/113, 34%) were used to measure dispersion, while few studies provide justifications regarding why the methods being selected. Inferential statistics were frequently conducted (93/113, 82%), with one-way ANOVA being most popular (52/93, 56%), yet few studies conducted either normality or equal variance test. These results suggest that more consistent and appropriate use of statistical method is necessary which may enhance the role of toxicology in public health.