Current Pharmaceutical Design - Volume 26, Issue 44, 2020

The Block Relevance (BR) analysis with its recent implementation in MATLAB is a computational tool that allows deconvoluting the balance of intermolecular interactions governing a given drug discoveryrelated phenomenon described by a QSPR/PLS model. Here we discuss a few applications to show how BR analysis can make faster and more efficient the assessment of the drug-likeness of drug candidates. First, we describe how identifying the best chromatographic system provides reliable log Poct surrogates and log P in apolar environments. Then we focus on permeability and show how BR analysis allows to check the universality of passive permeability among cell types and the identification of the PAMPA method that provides the same picture in terms of balance of intermolecular interactions as cell-based systems.

Background: The growing evidence that G protein-coupled receptors (GPCRs) not only form oligomers but that the oligomers also may modulate the receptor function provides a promising avenue in the area of drug design. Highly selective drugs targeting distinct oligomeric sub-states offer the potential to increase efficacy while reducing side effects. In this regard, determining the various oligomeric configurations and geometric sub-states of a membrane receptor is of utmost importance. Methods: In this report, we have reviewed two techniques that have proven to be valuable in monitoring the quaternary structure of proteins in vivo: Frster resonance energy transfer (FRET) spectrometry and fluorescence intensity fluctuation (FIF) spectrometry. In FRET spectrometry, distributions of pixel-level FRET efficiency are analyzed using theoretical models of various quaternary structures to determine the geometry and stoichiometry of protein oligomers. In FIF spectrometry, spatial fluctuations of fluorescent molecule intensities are analyzed to reveal quantitative information on the size and stability of protein oligomers. Results: We demonstrate the application of these techniques to a number of different fluorescence-based studies of cells expressing fluorescently labeled membrane receptors, both in the presence and absence of various ligands. The results show the effectiveness of using FRET spectrometry to determine detailed information regarding the quaternary structure receptors form, as well as FIF and FRET for determining the relative abundance of different-sized oligomers when an equilibrium forms between such structures. Conclusion: FRET and FIF spectrometry are valuable techniques for characterizing membrane receptor oligomers, which are of great benefit to structure-based drug design.

Drug discovery efforts for new covalent inhibitors have drastically increased in the last few years. The binding mechanism of covalent compounds entails the formation of a chemical bond between their electrophilic warhead group and the protein of interest. The use of moderately reactive warheads targeting nonconserved nucleophilic residues can improve the affinity and selectivity profiles of covalent binders as compared to their non-covalent analogs. Recent advances have also enabled their use as chemical probes to disclose novel and also less tractable targets. Increasing interest in covalent drug discovery prompted the development of new computational tools, including covalent docking methods, that are available to predict the binding mode and affinity of covalent ligands. These tools integrate conventional non-covalent docking and scoring schemes by modeling the newly formed covalent bond and the interactions occurring at the reaction site. In this review, we provide a thorough analysis of state-of-the-art covalent docking programs by highlighting their main features and current limitations. Focusing on the implemented algorithms, we show the differences in handling the formation of the new covalent bond and their relative impact on the prediction. This analysis provides a comprehensive overview of the current technology and suggests future improvements in computer-aided covalent drug design. Finally, discussing successful retrospective and prospective covalent docking-based virtual screening applications, we intend to identify best practices for the drug discovery community.

Combinations of different technologies are at the heart of the development and implementation of new, innovative processes and approaches for Industry 4.0 in the field of medicinal chemistry and drug discovery. Process intensification and advances in high-throughput synthetic techniques can dramatically improve reaction rates in processes for which slow kinetics represents a bottleneck. Easier access to target-based chemical library collections offers wider access to new leads for drug development. Green enabling technologies are a reliable ally for the design of environmentally friendly synthetic processes and more highly competitive pharmaceutical production. Mechanochemistry, microwaves, ultrasound and flow chemistry are mature techniques that can boast drug synthesis when properly integrated into the production chain. In this review, we selected examples from the literature of the last five years related to medicinal chemistry.

Background: As not all target proteins can be easily screened in vitro, advanced virtual screening is becoming critical. Objective: In this study, we demonstrate the application of reinforcement learning guided virtual screening for γ-aminobutyric acid A receptor (GABAAR) modulating peptides. Methods: Structure-based virtual screening was performed on a receptor homology model. Screened molecules deemed to be novel were synthesized and analyzed using patch-clamp analysis. Results: 13 molecules were synthesized and 11 showed positive allosteric modulation, with two showing 50% activation at the low micromolar range. Conclusion: Reinforcement learning guided virtual screening is a viable method for the discovery of novel molecules that modulate a difficult to screen transmembrane receptor.

Background: Skin is the largest organ of the body and helps to regulate several physiological functions. It acts as a barrier that protects the body against UV-radiation, toxic substances, infections, etc. The abnormal growth of the skin cells is called skin cancer. Different types of skin cancer can be classified as Basal Cell Carcinoma (BCC) and Squamous Cell Carcinoma (SCC); which mainly occur due to chronic exposure to UV- sunlight and pollution. Methods: The conventional topical treatments of skin cancer such as cream, gel, ointment, etc., are more occlusive and thus they do not penetrate deep into the skin (dermal layer) and remain at the upper part of the skin (epidermal layer). The stratum corneum acts as a physiological barrier for the drug-loaded in the conventional formulation. The novel carrier systems have the potential to facilitate the penetration of the drug deep into the skin (dermal layer) because these have less size and higher flexibility than conventional treatment. Conclusion: In the present review, we have discussed various novel carrier systems being investigated for the topical application of chemotherapeutic agents for efficient skin targeting and better dermatological as well as therapeutic benefits with minimal systemic exposure and toxicity.

Background: Meteorin-like (Metrnl) is a newly identified adipokine implicated in the pathogenesis of type 2 diabetes mellitus (T2DM), yet data on the circulating levels of Metrnl in patients with T2DM are controversial. To derive a more precise estimation on circulating Metrnl levels in T2DM patients, we conducted this meta-analysis. Methods: The existing studies on the circulating levels of Metrnl in patients with T2DM published up to 16 January 2020 were comprehensively retrieved from PubMed, Web of Science, EMBASE, and The Cochrane library database. Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated using random-effects model. Heterogeneity was assessed and quantified by Cochrane’s Q and I2 statistic. All statistical analyses were performed using Stata 12.0 software. Results: Nine studies with 867 T2DM patients and 831 normal glucose tolerance (NGT) controls were included in the final analysis according to the inclusion criteria. No significant difference in circulating Metrnl levels was found between T2DM patients and NGT individuals (pooled SMD = -0.429, 95% CI = -1.077 to 0.219). Compared to controls, circulating Metrnl levels were significantly higher in the subgroups with BMI <25 kg/m2, using plasma sample and patient sample size ≥100, while circulating Metrnl levels were significantly lower in subgroups with age ≤50 years and homeostatic model assessment for insulin resistance (HOMA-IR) ≥4. Conclusion: This meta-analysis indicates no significant change in circulating Metrnl levels in T2DM patients. However, this result may be influenced by age, BMI, sample type, HOMA-IR and patients sample size. Further longitudinal studies are warranted to offer more insights into the relationship between Metrnl and T2DM.

Objective: The aim was to evaluate the efficacy and safety of duration of dual antiplatelet therapy (DAPT) for patients who received percutaneous coronary intervention (PCI) with a drug-eluting stent. Background: The optimal duration of DAPT to balance the risk of ischemia and bleeding in CAD patients undergoing drug-eluting stent (DES) implantation remains controversial. Methods: PubMed, Cochrane Library, Web of Science, Clinicaltrials.gov, CNKI and Wanfang Databases were searched for randomized controlled trials of comparing different durations of DAPT after DES implantation. Primary outcomes were major adverse cardiac and cerebrovascular events (MACCE), and major bleeding, and were pooled by Bayes network meta-analysis. Net adverse clinical and cerebral events were used to estimate the surface under the cumulative ranking (SUCRA) curves. The subgroup analysis based on clinical status, follow-up and area was conducted using traditional pairwise meta-analysis. Results: A total of nineteen trials (n=51,035) were included, involving six duration strategies. The network metaanalysis showed that T2 (<6-month DAPT followed by aspirin, HR:1.51, 95%CI:1.02-2.22), T3 (standard 6-month DAPT, HR:1.47, 95%CI:1.14-1.91), T4 (standard 12-month DAPT, HR:1.41, 95%CI:1.15-1.75) and T5 (18-24 months DAPT, HR:1.47, 95%CI:1.09-1.97) was associated with significantly increased risk of MACCE compared to T6 (>24-month DAPT). However, no significant difference was found in MACCE risk between T1 (<6-month DAPT followed by P2Y12 monotherapy) and T6. Moreover, T5 was associated with significantly increased risk of bleeding compared to T1(RR:3.94, 95%CI:1.66-10.60), T2(RR:3.65, 95%CI:1.32-9.97), T3(RR:1.93, 95%CI:1.21-3.50) and T4(RR:1.89, 95%CI:1.15-3.30). The cumulative probabilities showed that T6(85.0%), T1(78.3%) and T4(44.5%) were the most efficacious treatment compared to the other durations. In the ACS (<50%) subgroup, T1 was observed to significantly reduce the risk of major bleeding compared to T4, but not in the ACS (≥50%) subgroup. Conclusion: Compared with other durations, short DAPT followed by P2Y12 inhibitor monotherapy showed non-inferiority, with a lower risk of bleeding and not associated with an increased MACCE. In addition, the risk of major bleeding increased significantly, starting with DAPT for 18-month. Compared with the short-term treatment, patients with ACS with the standard 12-month treatment have a better prognosis, including lower bleeding rate and the decreased risk of MACCE. Due to study's limitations, the results should be verified in different risk populations.

Background: Zacopride, a potent antagonist of 5-HT3 receptors and an agonist of 5-HT4 receptors, is a gastrointestinal prokinetic agent. In a previous study, we discovered that zacopride selectively stimulated the inward rectifier potassium current (IK1) in the rat and that agonizing IK1 prevented or eliminated aconitine-induced arrhythmias in rats. Objective: Our aims were to confirm that the antiarrhythmic effects of zacopride are mediated by selectively enhancing IK1 in rabbits. Methods: The effects of zacopride on the function of the main ion channels were investigated using a whole-cell patch-clamp technique in rabbits. Effects of zacopride on cardiac arrhythmias were also explored experimentally both in vivo and in vitro. Results: Zacopride moderately enhanced cardiac IK1 but had no apparent action on voltage-gated sodium current (INa), L- type calcium current (ICa-L), sodium-calcium exchange current (INa/Ca), transient outward potassium current (Ito), or delayed rectifier potassium current (IK) in rabbits. Zacopride also had a marked antiarrhythmic effect in vivo and in vitro. We proved that the resting membrane potential (RMP) was hyperpolarized in the presence of 1 μmol/L zacopride, and the action potential duration (APD) at 90% repolarization (APD90) was shortened by zacopride (0.1-10 μmol/L) in a concentration- dependent manner. Furthermore, zacopride at 1 μmol/L significantly decreased the incidence of drug-induced early afterdepolarization (EAD) in rabbit ventricular myocytes. Conclusion: Zacopride is a selective agonist of rabbit cardiac IK1 and that IK1 enhancement exerts potential antiarrhythmic effects.

Background: Oxaliplatin (OXP), a 3rd generation platinum compound, which causes severe side effects due to; impulse high concentration in the bloodstream thereby exposing healthy cells at a high ratio, nonspecific delivery at the target site and non-compliance is administered intravenously. Objective: The project was aimed at the development, characterization, and in-vitro and in-vivo evaluation of pHresponsive hydrogels for oral administration of OXP. Methods: Hydrogel formulations were synthesized through a free radical polymerization technique followed by brief characterization using various techniques. The hydrogels were investigated for various in-vitro studies such as sol-gel, drug loading, swelling, drug release, and MTT-assay. While in-vivo studies such as oral tolerability, histopathology, and hematology studies were performed on rabbits. A simple and sensitive HPLC-UV method was optimized and the comparative pharmacokinetic study was performed in rabbits using OXP-oral solution and OXP-loaded hydrogels. Results: In-vitro characterization confirmed that the reactant was successfully crosslinked to form thermally stable hydrogels with decreased crystallinity and rough surface. Swelling and drug release showed that hydrogels were more responsive to basic pH (6.8 and 7.4) in comparison with pH 1.2. The blank hydrogels were cytocompatible as more than 95% of the cells were viable while free OXP and OXP-loaded hydrogels displayed dosedependent cytotoxic effect. In-vivo studies confirmed that chitosan and gelatin hydrogel suspension was well tolerable up to 3800 mg/kg and 4000 mg/kg of body weight, respectively. Hematology and serum chemistry reports were well within the range suggesting normal liver and kidney functions. Similarly, histopathology slides of rabbit vital organs were also found normal without causing any histopathological change. Conclusion: HPLC-UV method was successfully optimized for OXP detection in oral solution and hydrogels administered to rabbits. A significant difference was found among various pharmacokinetic parameters by comparing the two groups including half-life (t1/2), tmax, Cmax, AUCtot MRT, Vz, and Lz.