Parallel Artificial Membrane Permeability Assay Research Articles

Formulation and Characterization of Raloxifene Nanostructured Lipid Carriers for Permeability and Uptake Enhancement Applications.

Raloxifene (RLX), a biopharmaceutical classification system (BCS) class II drug, is a selective estrogen receptor modulator (SERM) having an estrogenic effect on the bone and an antiestrogenic effect on the endometrium and breast. Low solubility, high permeability, high metabolism, and low bioavailability are the characteristics of raloxifene. Although 60% is absorbed orally, raloxifene shows extremely poor bioavailability (2%) owing to its low solubility and extensive (>90%) intestinal/hepatic first-pass metabolism. Hence, it becomes important to increase the solubility of raloxifene to enhance its bioavailability. In this study, raloxifene nanostructured lipid carriers (RNLCs) were prepared using the melt dispersion ultrasonication method. The prepared RNLCs were characterized, and the in vitro studies were carried out in the human epithelial breast cancer cell line (MCF-7). The RNLCs had a size of 114.8 ± 0.98 nm and a zeta potential of +9.21 ± 0.58 mV. Transmission electron microscopy (TEM) images showed particle size ranging from 65 to 120 nm. With an entrapment efficiency of 75.04% ± 2.75%, the RNLCs showed sustained release over 7 days compared with the raloxifene drug solution. The prepared RNLCs were successfully taken up by the MCF-7 cells in a time-dependent manner, and the RNLCs showed increased cell cytotoxicity compared with the raloxifene drug. Using the parallel artificial membrane permeability assay (PAMPA), the permeability rate for raloxifene solution was calculated to be 8 × 10-6 cm/s, and for the RNLCs, it was calculated to be 17.8 × 10-6 cm/s. Hence, from the permeability rate calculated, we could conclude that raloxifene, when formulated as nanostructured lipid carriers, showed increased permeability. Overall, the prepared RNLCs were found to be superior to the raloxifene drug as such.

Solubility and Permeability Enhancement of Oleanolic Acid by Solid Dispersion in Poloxamers and γ-CD.

Oleanolic acid (OA) is a pentacyclic triterpenoid widely found in the Oleaceae family, and it represents 3.5% of the dry weight of olive leaves. OA has many pharmacological activities, such as hepatoprotection, anti-inflammatory, anti-oxidant, anti-diabetic, anti-tumor, and anti-microbic activities. Its therapeutic application is limited by its poor water solubility, bioavailability, and permeability. In this study, solid dispersions (SDs) were developed to overcome these OA limitations. Solubility studies were conducted to evaluate different hydrophilic polymers, drug-to-polymer ratios, and preparation methods. Poloxamer 188, Poloxamer 407, and γ-CD exhibited the highest increases in terms of OA solubility, regardless of the method of preparation. Binary systems were characterized using differential scanning calorimetry (DSC), X-ray diffraction (XRPD), and Fourier transform infrared spectroscopy (FTIR). In addition, pure compounds and SDs were analyzed using scanning electron microscopy (SEM) in order to observe both the morphology and the particle surface. In vitro dissolution studies were performed for P407, P188, and γ-CD SDs. Preparation using the solvent evaporation method (SEM) produced the highest increase in the dissolution profiles of all three polymers with respect to the OA solution. Finally, the effect of SDs on OA permeability was evaluated with an in vitro parallel artificial membrane permeability assay (PAMPA). The formulation improved passive permeation across the simulated barrier due to OA increased solubility. The dissolution and PAMPA results indicate that the amorphization of OA by SD preparation could be a useful method to enhance its oral absorption, and it is also applicable on an industrial scale.

Biopharmaceutics studies applied to goyazensolide: a drug candidate from Lychnophora species.

To predict the substance's behaviour in vivo and determine the viability of the bioactive substance to become a drug, this work aimed to evaluate the biopharmaceutics characteristics of goyazensolide. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were applied for the characterization of goyazensolide. The biopharmaceutics characteristics were evaluated using in-silico and in-vitro (shake-flask and Parallel Artificial Membrane Permeability Assay) methods. DSC curve showed a single endothermic peak. According to the TG curve, goyazensolide has thermal stability close to 221.0°C and 210.0°C, under a nitrogen and oxygen atmosphere, respectively. In-silico data indicated that goyazensolide has high solubility and low permeability. The high solubility was confirmed by equilibrium solubility studies determined by the shake-flask method. The dose/solubility ratio values were 175.16 ml (pH 1.2), 194.99 ml (pH 4.5) and 222.07 ml (pH 6.8). The effective permeability of 0.03 × 10-6 cm/s was obtained for goyazensolide. This value is lower than furosemide (1.03 × 10-6 cm/s), confirming the low permeability of goyazensolide. Biopharmaceutics characteristics of goyazensolide are similar to drugs available on the market and attest to the feasibility of starting the process of developing a formulation containing this substance.

Mechanistic bottom-up estimation of passive drug absorption from the gastrointestinal tract: Comparison among primary cultured human intestinal cells, Caco-2 cells, artificial membrane, and animal scale-up.

The fraction of drug absorbed (Fa) from the intestine is an important parameter to characterize the pharmacokinetics of a drug. We aimed to search for an experimental system that provides the best parameters for estimating the effective permeability (Peff) used for the bottom-up prediction of Fa. The absorption kinetics of 12 passively absorbed drugs were simulated by a compartment absorption transit (CAT) model using absorption parameters from four different experimental systems: human intestinal epithelial cell (HIEC) monolayer, Caco-2 monolayer, parallel artificial membrane permeability assay (PAMPA), and in situ rat intestinal perfusion. All absorption parameters were obtained from the literature. The in vitro apparent permeability coefficient (Papp) and rat in situ Peff were converted to human Peff using a bottom-up approach for each region, based on the morphological features of the human intestine. The simulated Fa values were compared to the respective observed values. Furthermore, plasma concentration profiles of the drugs were simulated by convolution using the time-course of the absorption rate simulated using the Peff values calculated from the HIEC Papp. The Fa values were best predicted by using the Peff values calculated from HEIC, within a 1.3-fold range of observed Fa in 11 out of 12 drugs. The simulated Cmax values of pharmacokinetic simulation using HIEC Papp fell within a 1.5-fold range of observed values for all the drugs examined. The HIEC monolayer was identified as the most suitable permeation parameter for estimating Fa and Cmax using a morphological feature-based bottom-up approach.

Impact of Cyclization and Methylation on Peptide Penetration through Droplet Interface Bilayers.

Cell-penetrating peptides enter cells via diverse mechanisms, such as endocytosis, active transport, or direct translocation. For the design of orally delivered cell-penetrating peptides, it is crucial to know the contribution of these different mechanisms. In particular, the ability of a peptide to translocate through a lipid bilayer remains a key parameter for the delivery of cargos. However, existing approaches used to assess translocation often provide discrepant results probably because they have different sensitivities to the distinct translocation mechanisms. Here, we focus on the passive permeation of a range of hydrophobic cyclic peptides inspired by somatostatin, a somatotropin release-inhibiting factor. Using droplet interface bilayers (DIB), we assess the passive membrane permeability of these peptides and study the impact of the peptide cyclization and backbone methylation on translocation rates. Cyclization systematically improved the permeability of the tested peptides while methylation did not. By studying the interaction of the peptides with the DIB interfaces, we found membrane insertion and peptide intrinsic diffusion to be two independent factors of permeability. Compared to the industrial gold standard Caco-2 and parallel artificial membrane permeability assay (PAMPA) models, DIBs provide intermediate membrane permeability values, closer to Caco-2. Even for conditions where Caco-2 and PAMPA are discrepant, the DIB approach also gives results closer to Caco-2. Thereupon, DIBs represent a robust alternative to the PAMPA approach for predicting the permeability of peptides, even if the latter present extremely small structural differences.

Lichen Secondary Metabolites Inhibit the Wnt/β-Catenin Pathway in Glioblastoma Cells and Improve the Anticancer Effects of Temozolomide.

Lichens are a source of secondary metabolites with significant pharmacological potential. Data regarding their possible application in glioblastoma (GBM) treatment are, however, scarce. The study aimed at analyzing the mechanism of action of six lichen secondary metabolites: atranorin, caperatic acid, physodic acid, squamatic acid, salazinic acid, and lecanoric acid using two- and three-dimensional GBM cell line models. The parallel artificial membrane permeation assay was used to predict the blood-brain barrier penetration ability of the tested compounds. Their cytotoxicity was analyzed using the MTT test on A-172, T98G, and U-138 MG cells. Flow cytometry was applied to the analysis of oxidative stress, cell cycle distribution, and apoptosis, whereas qPCR and microarrays detected the induced transcriptomic changes. Our data confirm the ability of lichen secondary metabolites to cross the blood-brain barrier and exert cytotoxicity against GBM cells. Moreover, the compounds generated oxidative stress, interfered with the cell cycle, and induced apoptosis in T98G cells. They also inhibited the Wnt/β-catenin pathway, and this effect was even stronger in case of a co-treatment with temozolomide. Transcriptomic changes in cancer related genes induced by caperatic acid and temozolomide were the most pronounced. Lichen secondary metabolites, caperatic acid in particular, should be further analyzed as potential anti-GBM agents.

Development and Optimization of Nanoemulsion from Ethanolic Extract of Centella asiatica (NanoSECA) Using D-Optimal Mixture Design to Improve Blood-Brain Barrier Permeability.

The evidence on the neuroprotective impact of Centella asiatica (C. asiatica) has been greatly documented in recent years. However, a major obstacle that remains to be overcome is the capacity of the active molecules in C. asiatica to cross the blood-brain barrier (BBB). In this study, we explored the possibilities of using a D-optimal mixture design to fabricate nanoemulsion of C. asiatica (NanoSECA) for better brain bioavailability. The parameters for optimization were the percentage of water (10–80% w/v) and virgin coconut oil (VCO) (10–80% w/v). Nanoemulsions were formulated using a high-pressure homogenization approach and were characterized for their physicochemical properties. The optimal VCO-based nanoemulsion (VBN: F2) conditions were found at 80% (w/v) of water and 10% (w/v) of VCO. Subsequently, viability tests were conducted on neuroblastoma (SH-SY5Y) and macrophage (RAW 264.7) cell lines. NanoSECA was distinguished for its antioxidant, acetylcholinesterase (AChE), anti-inflammatory, and parallel artificial membrane permeability assay (PAMPA) activities in vitro. The NanoSECA has a particle size of 127.833 ± 8.280 nm, zeta potential (ZP) of −24.9 ± 0.011 mV, polydispersity index (PDI) of 0.493 ± 4.681, percentage prediction error (PPE) of −12.02%, and pH of 6.0 ± 0.006 and is also stable under different storage conditions. Cell viability was improved in a dose-dependent manner on SH-SY5Y and RAW 264.7 cell lines. In addition, NanoSECA significantly reduced the AChE activity, suppressing the level of proinflammatory mediators and oxidative stress. Moreover, NanoSECA showed high BBB permeation with a high value of experimental permeability to cross the BBB. Thus, NanoSECA could efficiently potentiate the central nervous system (CNS) therapeutic activities through enhanced penetration of BBB. These nano-delivery systems are crucial to unlock the full potential of C. asiatica for treating numerous CNS disorders.

PE and PET oligomers\u2019 interplay with membrane bilayers

The prevalence of microplastic pollution in nature and foodstuffs is fairly well identified. However, studies of micro- or nanoplastics’ cell membrane permeation and health effects in humans are lacking. Our study focuses on examining the interactions of polyethylene (PE) and polyethylene terephthalate (PET) with bilayer membranes. We have performed molecular dynamics simulations to study how plastic oligomers behave in bilayers. In addition, we have studied membrane permeation of PE and Bis(2-hydroxyethyl) terephthalate (BHET), a type of PET monomer, with Parallel Artificial Membrane Permeability Assay (PAMPA). As a result, in simulations the molecules exhibited different movements and preferred locations in membrane. PAMPA studies suggested similar preferences in membrane, especially for PE plastic. Our results suggest that passive diffusion could be an important transport mechanism into cells for some small plastic oligomers. Both molecular dynamics simulations and PAMPA have potential for micro- and nanoplastics research.

Understanding the relationship between solubility and permeability of γ-cyclodextrin-based systems embedded with poorly aqueous soluble benznidazole

When administered orally, the bioavailability of drugs is strongly influenced by their aqueous solubility and permeability. Although solubility-enabling excipients can improve the aqueous solubility of lipophilic drugs, their simultaneous effect on the apparent permeability can be often overlooked. Recently, we demonstrated that the aqueous dissolution of poorly aqueous soluble benznidazole (BNZ) was improved by γ-CD complexation, but the potential impact of γ-CD complexation on the permeability of BNZ remained unexplored. Therefore, the aim of this work was to study the relationship between the aqueous solubility and apparent permeability of BNZ:γ-CD-based formulations, employing both non-cell-based parallel artificial membrane permeability assay (PAMPA) and cell-based (Caco-2 and mucus-producing Caco-2/HT29-MTX co-culture cell model) permeability models. The increase in BNZ aqueous solubility was directly proportional to the γ-CD concentration (from 185 µg mL−1 up to 320 µg mL−1 when 20 mM γ-CD was used in the formulation) and resulted in an increased apparent permeability, though in some cases a decrease was observed. Specifically, in the Caco-2/HT29-MTX cell model an increase in aqueous solubility did not always result in the increase of apparent permeability, with higher γ-CD concentrations leading to a decrease in apparent permeability Papp values down to 3.248 × 10–5 cm s−1 at γ-CD concentration of 30 mM (from 5.164 × 10–5 cm s−1 for 15 mM γ-CD) despite a continuing increase in solubility. Overall, the solubility enhancement of BNZ by γ-CD complexation had different effects on its permeability depending on the permeability model employed, and these effects should be taken into consideration when using solubility-enabling excipients.

Effect of electrospraying conditions on the properties of aspalathin‐Eudragit S100 nanoparticles and assessment of orogastrointestinal stability and membrane permeability

AbstractAspalathin, a C‐glucosyl dihydrochalcone, could have beneficial effects in the gut through the modulation of the microbiome. However, aspalathin is susceptible to oxidative degradation. The effect of electrospraying conditions on encapsulation of an aspalathin‐rich fraction prepared from green rooibos (GRAF; 40% aspalathin, m/m) with Eudragit S100 (ES100), a pH‐sensitive release polymer, was investigated to enhance the stability of aspalathin. Electrospraying conditions were varied according to a central composite design, using ES100 concentrations of 1–6% (m/m), GRAF concentrations of 5–25% (m/m, relative to polymer concentration), and voltages of 10–25 kV. The varying conditions produced nanoparticles ranging in yield (60.3–83.7%), encapsulation efficiency, (20.5–81.8%), loading capacity (1.0–14.9%), particle size (183–260 nm), and polydispersity index (0.35–0.74). The GRAF nanoparticles and nanoparticles prepared with pure aspalathin were evaluated for stability and release of aspalathin at fixed pH–time combinations (pH 6.8, 5 min; pH 2, 120 min; pH 4, 60 min; and pH 7, 120 min), simulating the pH and residence/transit time at various locations of the orogastrointestinal tract. Nanoencapsulation decreased aspalathin degradation at all pH‐time combinations (1.9–2.7 times less degradation; p < 0.05), except for pH 7, 120 min (p ≥ 0.05), thus offering protection from the pH of the upper gastrointestinal tract. Additionally, the parallel artificial membrane permeability assay and the Caco‐2 monolayer model indicated that the low membrane permeability of aspalathin after nanoencapsulation was maintained that would limit absorption, ideal for delivery in the gut. Thus, nanoencapsulated aspalathin holds potential for the regulation of gut microbiota.

The Systems of Naringenin with Solubilizers Expand Its Capability to Prevent Neurodegenerative Diseases.

Background: Naringenin (NAR) is a flavonoid with excellent antioxidant and neuroprotective potential that is limited by its low solubility. Thus, solid dispersions with β-cyclodextrin (β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), hydroxypropylmethylcellulose (HPMC), and microenvironmental pH modifiers were prepared. Methods: The systems formation analysis was performed by X-Ray Powder Diffraction (XRPD) and Fourier-transform infrared spectroscopy (FT-IR). Water solubility and dissolution rates were studied with a pH of 1.2 and 6.8. In vitro permeability through the gastrointestinal tract (GIT) and the blood-brain barrier (BBB) was assessed with the parallel artificial membrane permeability assay (PAMPA) assay. The antioxidant activity was studied with the 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and cupric ion reducing antioxidant capacity (CUPRAC) assays, while in vitro enzymes studies involved the inhibition of acetylcholinesterase, butyrylcholinesterase, and tyrosinase. For the most promising system, in silico studies were conducted. Results: NAR solubility was increased 458-fold by the solid dispersion NAR:HP-β-CD:NaHCO3 in a mass ratio of 1:3:1. The dissolution rate was elevated from 8.216% to 88.712% in a pH of 1.2 and from 11.644% to 88.843% in a pH of 6.8 (within 3 h). NAR GIT permeability, described as the apparent permeability coefficient, was increased from 2.789 × 10−6 cm s−1 to 2.909 × 10−5 cm s−1 in an acidic pH and from 1.197 × 10−6 cm s−1 to 2.145 × 10−5 cm s−1 in a basic pH. NAR BBB permeability was established as 4.275 × 10−6 cm s−1. The antioxidant activity and enzyme inhibition were also increased. Computational studies confirmed NAR:HP-β-CD inclusion complex formation. Conclusions: A significant improvement in NAR solubility was associated with an increase in its biological activity.

Flux-Based Formulation Development\u2014A Proof of Concept Study

The work aimed to develop the Absorption Driven Drug Formulation (ADDF) concept, which is a new approach in formulation development to ensure that the drug product meets the expected absorption rate. The concept is built on the solubility-permeability interplay and the rate of supersaturation as the driving force of absorption. This paper presents the first case study using the ADDF concept where not only dissolution and solubility but also permeation of the drug is considered in every step of the formulation development. For that reason, parallel artificial membrane permeability assay (PAMPA) was used for excipient selection, small volume dissolution-permeation apparatus was used for testing amorphous solid dispersions (ASDs), and large volume dissolution-permeation tests were carried out to characterize the final dosage forms. The API-excipient interaction studies on PAMPA indicated differences when different fillers or surfactants were studied. These differences were then confirmed with small volume dissolution-permeation assays where the addition of Tween 80 to the ASDs decreased the flux dramatically. Also, the early indication of sorbitol’s advantage over mannitol by PAMPA has been confirmed in the investigation of the final dosage forms by large-scale dissolution-permeation tests. This difference between the fillers was observed in vivo as well. The presented case study demonstrated that the ADDF concept opens a new perspective in generic formulation development using fast and cost-effective flux-based screening methods in order to meet the bioequivalence criteria.Graphical

Cystic Fibrosis Mucus Model to Design More Efficient Drug Therapies.

Mucus represents a strong barrier to tackle for oral or pulmonary administered drugs, especially in mucus-related disorders. This study uses a pathological cystic fibrosis (CF) mucus model to investigate how mucus impacts the passive diffusion of 45 ad hoc commercial drugs selected to maximize physicochemical variability. An in vitro mucosal surface was recreated by coupling the mucus model to a 96-well permeable support precoated with structured layers of phospholipids (parallel artificial membrane permeability assay, PAMPA). Results show that the mucus model was not a mere physical barrier but it behaves like an interactive filter. In nearly one-half of the investigated compounds, the diffusion was reduced by mucus, while other drugs were not sensitive to the mucus barriers. We also found that permeability can be enhanced when drug-calcium salts are formed. This was confirmed with cystic fibrosis sputum as a rough ex vivo model of CF mucus. Since the drug discovery process is characterized by a high rate of failure, the mucus platform is expected to provide an efficient support to early reduce the number of poor-performing drug candidates.

Exploration of Neuroprotective Properties of a Naturally Inspired Multifunctional Molecule (F24) against Oxidative Stress and Amyloid β Induced Neurotoxicity in Alzheimer's Disease Models.

The pathological hallmarks of Alzheimer's disease (AD) are manifested as an increase in the level of oxidative stress and aggregation of the amyloid-β protein. In vitro, in vivo, and in silico experiments were designed and carried out with multifunctional cholinergic inhibitor, F24 (EJMC-7a) to explore its neuroprotective effects in AD models. The neuroprotection ability of F24 was tested in SH-SY5Y cells, a widely used neuronal cell line. The pretreatment and subsequent co-treatment of SH-SY5Y cells with different doses of F24 was effective in rescuing the cells from H2O2 induced neurotoxicity. F24 treated cells were found to be effective in the reduction of cellular reactive oxygen species, DNA damage, and Aβ1-42 induced neurotoxicity, which validated its neuroprotective effectiveness. F24 exhibited efficacy in an in vivoDrosophila model by rescuing eye phenotypes from degeneration caused by Aβ toxicity. Further, computational studies were carried out to monitor the interaction between F24 and Aβ1-42 aggregates. The computational studies corroborated our in vitro and in vivo studies suggesting Aβ1-42 aggregation modulation ability of F24. The brain entry ability of F24 was studied in the parallel artificial membrane permeability assay. Finally, F24 was tested at doses of 1 and 2.5 mg/kg in the Morris water maze AD model. The neuroprotective properties shown by F24 strongly suggest that multifunctional features of this molecule provide symptomatic relief and act as a disease-modifying agent in the treatment of AD. The results from our experiments strongly indicated that natural template-based F24 could serve as a lead molecule for further investigation to explore multifunctional therapeutic agents for AD management.

Evaluation of the increase of the thymoquinone permeability formulated in polymeric micelles: In vitro test and in vivo toxicity assessment in Zebrafish embryos

Thymoquinone (TQ) is a natural compound present in the essential oil and in the fixed oil of Nigella sativa L. Like many natural substances, it is characterized by poor aqueous solubility and low stability which limit its bioavailability. Soluplus®-Solutol® HS15 polymeric micelles (TQ-MP) were developed to increase the permeability of TQ with particular attention to overcoming intestinal barrier and the blood brain barrier, for possible oral and parenteral administration. The optimized micelles have dimensions < 100 nm and PdI < 0.2 indicating that the formulation was homogeneous as confirmed also by TEM experiments. EE% was 92.4 ± 0.3%. Stability studies showed a stable formulation following subsequent dilutions and in the gastric-intestinal media.In vitro studies have revealed that the carrier enhances the permeability of TQ in the intestine and in the blood-brain barrier using Parallel Artificial Membrane Permeability Assay (PAMPA) assay and cellular tests with Caco-2 cells and hCMEC/D3 monolayer cells. Up-take study, cell viability and cytotoxicity studies were also conducted. Fluorescent micelles (FITC-MP), were also optimized to perform in vitro up-take study in Caco-2 cells and to study their toxicity in Zebrafish model. The toxicity was evaluated on three lines of Zebrafish: wild type, transgenic line Tg(Myl7:EGFP) in which cardiomyocytes are marked with green fluorescence protein and Tg(flk1-GFP) line which expresses GFP under the control of the vascular endothelial growth factor receptor 2 (vegfr2) promoter.

Imidazolylacetophenone oxime-based multifunctional neuroprotective agents: Discovery and structure-activity relationships

Alzheimer's disease (AD) possesses a complex pathogenetic mechanism. Nowadays, multitarget agents are considered to have potential in effectively treating AD via triggering molecules in functionally complementary pathways at the same time. Here, based on the screening (∼1400 compounds) against neuroinflammation, an imidazolylacetophenone oxime ether (IOE) was discovered as a novel hit. In order to obtain SARs, a series of imidazolylacetophenone oxime derivatives were constructed, and their C=N bonds were confirmed as the Z configuration by single crystals. These derivatives exhibited potential multifunctional neuroprotective effects including anti-neuroinflammatory, antioxidative damage, metal-chelating, inhibition of acetylcholinesterase (AChE) properties. Among these derivatives, compound 12i displayed the most potent inhibitory activity against nitric oxide (NO) production with EC50 value of 0.57 μM 12i can dose-dependently suppress the expression of iNOS and COX-2 but not change the expression of HO-1 protein. Moreover, 12i exhibited evidently neuroprotective effects on H2O2-induced PC12 cells damage and ferroptosis without cytotoxicity at 10 μM, as well as selectively metal chelating properties via chelating Cu2+. In addition, 12i showed a mixed-type inhibitory effect on AChE in vitro. The structure-activity relationships (SARs) analysis indicated that dioxolane groups on benzene ring and rigid oxime ester can improve the activity. Parallel artificial membrane permeation assay (PAMPA) also verified that 12i can overcome the blood-brain barrier (BBB). Overall, this is the first report on imidazolylacetophenone oxime-based multifunctional neuroprotective effects, suggesting that this type of compounds might be novel multifunctional agents against AD.

Replacement of Chalcone-Ethers with Chalcone-Thioethers as Potent and Highly Selective Monoamine Oxidase-B Inhibitors and Their Protein-Ligand Interactions.

To develop new potent and highly selective MAO-B inhibitors from chalcone-thioethers, eleven chalcones-thioethers were synthesized and their monoamine oxidase (MAO) inhibition, kinetics, reversibility, and cytotoxicity of lead compounds were analyzed. Molecular dynamics were carried out to investigate the interactions. Compound TM8 showed potent inhibitory activity against MAO-B, with an IC50 value of 0.010 µM, followed by TM1, TM2, TM7, and TM10 (IC50 = 0.017, 0.021, 0.023, and 0.026 µM, respectively). Interestingly, TM8 had an extremely high selectivity index (SI; 4860) for MAO-B. Reversibility and kinetic experiments showed that TM8 and TM1 were reversible and competitive inhibitors of MAO-B with Ki values of 0.0031 ± 0.0013 and 0.011± 0.001 µM, respectively. Both TM1 and TM8 were non-toxic to Vero cells with IC50 values of 241.8 and 116.3 µg/mL (i.e., 947.7 and 402.4 µM), respectively, and at these IC50 values, both significantly reduced reactive oxygen species (ROS) levels. TM1 and TM8 showed high blood-brain barrier permeabilities in the parallel artificial membrane permeability assay. Molecular dynamics studies were conducted to investigate interactions between TM1 and TM8 and the active site of MAO-B. Conclusively, TM8 and TM1 are potent and highly selective MAO-B inhibitors with little toxicity and good ROS scavenging abilities and it is suggested that both are attractive prospective candidates for the treatment of neurological disorders.

Multi-Target Effects of Novel Synthetic Coumarin Derivatives Protecting Aβ-GFP SH-SY5Y Cells against Aβ Toxicity.

Alzheimer’s disease (AD) is a common neurodegenerative disease presenting with progressive memory and cognitive impairments. One of the pathogenic mechanisms of AD is attributed to the aggregation of misfolded amyloid β (Aβ), which induces neurotoxicity by reducing the expression of brain-derived neurotrophic factor (BDNF) and its high-affinity receptor tropomyosin-related kinase B (TRKB) and increasing oxidative stress, caspase-1, and acetylcholinesterase (AChE) activities. Here, we have found the potential of two novel synthetic coumarin derivatives, ZN014 and ZN015, for the inhibition of Aβ and neuroprotection in SH-SY5Y neuroblastoma cell models for AD. In SH-SY5Y cells expressing the GFP-tagged Aβ-folding reporter, both ZN compounds reduced Aβ aggregation, oxidative stress, activities of caspase-1 and AChE, as well as increased neurite outgrowth. By activating TRKB-mediated extracellular signal-regulated kinase (ERK) and AKT serine/threonine kinase 1 (AKT) signaling, these two ZN compounds also upregulated the cAMP-response-element binding protein (CREB) and its downstream BDNF and anti-apoptotic B-cell lymphoma 2 (BCL2). Knockdown of TRKB attenuated the neuroprotective effects of ZN014 and ZN015. A parallel artificial membrane permeability assay showed that ZN014 and ZN015 could be characterized as blood–brain barrier permeable. Our results suggest ZN014 and ZN015 as novel therapeutic candidates for AD and demonstrate that ZN014 and ZN015 reduce Aβ neurotoxicity via pleiotropic mechanisms.

Combined Methodologies for Determining In Vitro Bioavailability of Drugs and Prediction of In Vivo Bioequivalence From Pharmaceutical Oral Formulations.

With the aim of developing an in vitro model for the bioavailability (BA) prediction of drugs, we focused on the study of levonorgestrel (LVN) released by 1.5 mg generic and brand-name tablets. The developed method consisted in combining a standard dissolution test with an optimized parallel artificial membrane permeability assay (PAMPA) to gain insights into both drug release and gastrointestinal absorption. Interestingly, the obtained results revealed that the tablet standard dissolution test, combined with an optimized PAMPA, highlighted a significant decrease in the release (15 ± 0.01 μg min−1 vs 30 ± 0.01 μg min−1) and absorption (19 ± 7 × 10–6 ± 7 cm/s Pe vs 41 ± 15 × 10–6 cm/s Pe) profiles of a generic LVN tablet when compared to the brand-name formulation, explaining unbalanced in vivo bioequivalence (BE). By using this new approach, we could determine the actual LVN drug concentration dissolved in the medium, which theoretically can permeate the gastrointestinal (GI) barrier. In fact, insoluble LVN/excipient aggregates were found in the dissolution media giving rise to non-superimposable dissolution profiles between generic and brand-name LVN tablets. Hence, the results obtained by combining the dissolution test and PAMPA method provided important insights confirming that the combined methods can be useful in revealing crucial issues in the prediction of in vivo BE of drugs.

Application of in vitro PAMPA technique and in silico computational methods for blood-brain barrier permeability prediction of novel CNS drug candidates

Permeability assessment of small molecules through the blood-brain barrier (BBB) plays a significant role in the development of effective central nervous system (CNS) drug candidates. Since in vivo methods for BBB permeability estimation require a lot of time and resources, in silico and in vitro approaches are becoming increasingly popular nowadays for faster and more economical predictions in early phases of drug discovery. In this work, through application of in vitro parallel artificial membrane permeability assay (PAMPA-BBB) and in silico computational methods we aimed to examine the passive permeability of eighteen compounds, which affect serotonin and dopamine levels in the CNS. The data set was consisted of novel six human dopamine transporter (hDAT) substrates that were previously identified as the most promising lead compounds for further optimisation to achieve neuroprotective effect, twelve approved CNS drugs, and their related compounds. Firstly, PAMPA methods was used to experimentally determine effective BBB permeability (Pe) for all studied compounds and obtained results were further submitted for quantitative structure permeability relationship (QSPR) analysis. QSPR models were built by using three different statistical methods: stepwise multiple linear regression (MLR), partial least square (PLS), and support-vector machine (SVM), while their predictive capability was tested through internal and external validation. Obtained statistical parameters (MLR- R2pred=-0.10; PLS- R2pred=0.64, r2m=0.69, r/2m=0.44; SVM- R2pred=0.57, r2m=0.72, r/2m=0.55) indicated that the SVM model is superior over others. The most important molecular descriptors (H0p and SolvEMt_3D) were identified and used to propose structural modifications of the examined compounds in order to improve their BBB permeability. Moreover, steered molecular dynamics (SMD) simulation was employed to comprehensively investigate the permeability pathway of compounds through a lipid bilayer. Taken together, the created QSPR model could be used as a reliable and fast pre-screening tool for BBB permeability prediction of structurally related CNS compounds, while performed MD simulations provide a good foundation for future in silico examination.