Synthesis, physicochemical characterization, and investigation of anti-inflammatory activity of water-soluble PEGylated 1,2,4-Triazoles.

A series of water-soluble PEGylated 1,2,4-triazoles 5-8 were successfully synthesized from methyl 5-(chloromethyl)-1-aryl-1H-1,2,4-triazole-3-carboxylates 1. All of the water-soluble PEGylated 1,2,4-triazoles were characterized by FT-IR and 1H NMR spectroscopy. The solubility, in vitro plasma stability, and anti-inflammatory activity were also determined and compared to original methyl 5-(halomethyl)-1-aryl-1H-1,2,4-triazole-3-carboxylates. For SAR study, all PEGylated 1,2,4-triazoles 5-8 performed potential anti-inflammatory activity on LPS-induced RAW 264.7 cells (IC50 = 3.42-7.81 µM). Moreover, the western blot result showed PEGylated 1,2,4-triazole 7d performed 5.43 and 2.37 folds inhibitory activity over iNOS and COX-2 expressions. On the other hand, the cell viability study revealed PEGylated 1,2,4-triazoles 7 and 8 with PEG molecular weight more than 600 presented better cell safety (cell viability > 95 %). Through the solubility and in vitro plasma stability studies, PEGylated 1,2,4-triazoles 7a-d exhibited higher hydrophilicity and prolonged 2.01 folds of half-life in compound 7d. Furthermore, the in vivo anti-inflammatory and gastric safety results indicated PEGylated 1,2,4-triazole 7d more effectively decreased the inflammatory response in edema and COX-2 expression and exhibited higher gastric safety than Indomethacin. Following the in vitro and in vivo study results, PEGylated 1,2,4-triazole 7d possessed favorable solubility, plasma stability features, safety, and significant anti-inflammatory activity to become the potential water-soluble anti-inflammatory candidate.

Discovery of neuroprotective Agents: Potent, brain Penetrating, lipoic acid derivatives for the potential treatment of ischemic stroke by regulating oxidative stress and inflammation - a Preliminary study.

Stroke poses a serious risk to the physical and mental health of patients. Endogenous compounds are widely used to treat ischemic stroke. Lipoic acid, a naturally occurring (R)-5-(1,2-dithiolan-3-yl)pentanoic acid, has therapeutic potential for the treatment of ischemic stroke. However, the direct application of lipoic acid is limited by its relatively low efficacy and instability. Therefore, there is a need to modify the structure of lipoic acid to improve its pharmaceutical capabilities. Currently, 37 lipoic acid derivatives have been synthesized, and compound AA-9 demonstrated optimal therapeutic potential in an in vitro model of induced oxidative damage using tert-butyl hydroperoxide (t-BHP). In addition, in vitro experiments have shown that compound AA-9 has an excellent safety profile. Subsequently, the therapeutic effect of AA-9 was significant in the rat MCAO ischemic stroke model, which may be attributed to the antioxidant and anti-inflammatory effects of compound AA-9 by activating PGC-1α and inhibiting NLRP3. Notably, compound AA-9 exhibited higher stability and better bioavailability properties than ALA in plasma stability and pharmacokinetic properties. In conclusion, AA-9 may be a promising neuroprotective agent for the treatment of ischemic stroke and warrants further investigation.

The stability of 65 biochemistry analytes in plasma, serum, and whole blood.

OBJECTIVES: The pre-analytical stability of various biochemical analytes requires careful consideration, as it can lead to the release of erroneous laboratory results. There is currently significant variability in the literature regarding the pre-analytical stability of various analytes. The aim of this study was to determine the pre-analytical stability of 65 analytes in whole blood, serum and plasma using a standardized approach. METHODS: Blood samples were collected from 30 healthy volunteers (10 volunteers per analyte) into five vacutainers; either SST, Li-heparin, K2-EDTA, or Na-fluoride/K-oxalate. Several conditions were tested, including delayed centrifugation with storage of whole blood at room temperature (RT) for 8 h, delayed centrifugation with storage of whole blood at RT or 4 °C for 24 h, and immediate centrifugation with storage of plasma or serum at RT for 24 h. Percent deviation (% PD) from baseline was calculated for each analyte and compared to the maximum permissible instability (MPI) derived from intra- and inter-individual biological variation. RESULTS: The majority of the analytes evaluated remained stable across all vacutainer types, temperatures, and timepoints tested. Glucose, potassium, and aspartate aminotransferase, among others, were significantly impacted by delayed centrifugation, having been found to be unstable in whole blood specimens stored at room temperature for 8 h. CONCLUSIONS: The data presented provides insight into the pre-analytical variables that impact the stability of routine biochemical analytes. This study may help to reduce the frequency of erroneous laboratory results released due to exceeded stability and reduce unnecessary repeat phlebotomy for analytes that remain stable despite delayed processing.

PredPS: Attention-based graph neural network for predicting stability of compounds in human plasma.

Stability of compounds in the human plasma is crucial for maintaining sufficient systemic drug exposure and considered an essential factor in the early stages of drug discovery and development. The rapid degradation of compounds in the plasma can result in poor in vivo efficacy. Currently, there are no open-source software programs for predicting human plasma stability. In this study, we developed an attention-based graph neural network, PredPS to predict the plasma stability of compounds in human plasma using in-house and open-source datasets. The PredPS outperformed the two machine learning and two deep learning algorithms that were used for comparison indicating its stability-predicting efficiency. PredPS achieved an area under the receiver operating characteristic curve of 90.1%, accuracy of 83.5%, sensitivity of 82.3%, and specificity of 84.6% when evaluated using 5-fold cross-validation. In the early stages of drug discovery, PredPS could be a helpful method for predicting the human plasma stability of compounds. Saving time and money can be accomplished by adopting an in silico-based plasma stability prediction model at the high-throughput screening stage. The source code for PredPS is available at https://bitbucket.org/krict-ai/predps and the PredPS web server is available at https://predps.netlify.app.

Determination of structural features that underpin the pannexin1 channel inhibitory activity of the peptide 10Panx1.

Pannexin1 channels facilitate paracrine communication and are involved in a broad spectrum of diseases. Attempts to find appropriate pannexin1 channel inhibitors that showcase target-selective properties and in vivo applicability remain nonetheless scarce. However, a promising lead candidate, the ten amino acid long peptide mimetic 10Panx1 (H-Trp1-Arg2-Gln3-Ala4-Ala5-Phe6-Val7-Asp8-Ser9-Tyr10-OH), has shown potential as a pannexin1 channel inhibitor in both in vitro and in vivo studies. Nonetheless, structural optimization is critical for clinical use. One of the main hurdles to overcome along the optimization process consists of subduing the low biological stability (10Panx1 t1/2 = 2.27 ± 0.11 min). To tackle this issue, identification of important structural features within the decapeptide structure is warranted. For this reason, a structure-activity relationship study was performed to proteolytically stabilize the sequence. Through an Alanine scan, this study demonstrated that the side chains of Gln3 and Asp8 are crucial for 10Panx1's channel inhibitory capacity. Guided by plasma stability experiments, scissile amide bonds were identified and stabilized, while extracellular adenosine triphosphate release experiments, indicative of pannexin1 channel functionality, allowed to enhance the in vitro inhibitory capacity of 10Panx1.

LC/Q-TOF MS and LC/QQQ MS based bioanalysis of a new ferrocene derivative as a potential anticancer lead with promising drug-like characteristics.

Pyrazolopyrimidine ring present in various approved drugs is reported to target the tyrosine kinase receptor. A new pyrazolopyrimidine ferrocene derivative, which targets tumor pyruvate kinase M2 showed an impressive antiproliferative profile against human oral squamous cell carcinoma cell line CAL27 assessed using Alamar blue assay. In line with the lead optimization process, the molecule was studied for physicochemical properties where a bioanalytical method has been developed in plasma on liquid chromatography-mass spectrometry and validated following the USFDA bioanalytical method validation guideline. Plasma stability and plasma protein binding potential of the molecule have been evaluated. All the major metabolites of the compound have been identified through in vitro metabolite study employing rat liver microsome, human liver microsome, and human S9 fractions. The in silico toxicity profile of the metabolites was assessed using ProTox II software. Log P, Log D, and pKa of the molecule were found to be 4.5, 5, and 12, respectively. The molecule was found to be quite stable in plasma and have a moderate affinity towards plasma proteins (about 75 % binding). Four major metabolites have been identified and characterized by UHPLCQ-TOF-MS. The metabolites were found to have a moderate safety profile. The validated bioanalytical method and the metabolic pathway will be useful for future clinical studies and to assess the safety profile of the molecule. The finding of this study may also be useful in analyzing the desired drug-like properties through bioanalysis while designing new chemical entities based on metallocenes.

Novel Multipotent Amantadine-M30D Hybrids with Highly Selective Butyrylcholinesterase Inhibition and Neuroprotective Effects as Effective Anti-Alzheimer's Agents.

As a contribution to the development of new dual/multifunctional drugs, a novel therapeutical scaffold merging key structural features from memantine and M30D was designed, synthesized, and explored for its AChE/BuChE inhibitory activity and neuroprotective effects. All synthetized hybrids were not able to inhibit AChE, but most of them exhibit inhibition with high selectivity toward butyrylcholinesterase (BuChE). Notably, among the tested compounds, amantadine/M30D hybrids with six, seven, nine, and twelve methylene groups in the spacer (5d, 5e, 5f, and 5g) not only highlighted having the best potency and selective butyrylcholinesterase inhibition greater than 83% but also, particularly 5e and 5d, elicited considerable neuroprotection when evaluated in pretreatment conditions, by reducing injury effects caused by glutamate with maximum protection reached about 47.82 ± 0.81% (5e) and 42 ± 2.20% (5d) in comparison with memantine (37.27 ± 2.69%). Likewise, we chose 5e as the hit compound, which in a glutamate excitotoxity coculture model prevented astroglia reactivity and neuronal death, as well as a 91% restoration of calcium levels and an increasing ATP level in both pre-/post-treatments of 61.48 ± 4.60 and 45.16 ± 10.55%, respectively. Regarding docking studies, a blockade of the NMDA channel pore by 5e would explain its neuroprotective response. Finally, the hit compound 5e exhibited in vitro blood-brain barrier (BBB) permeability and human plasma stability, as well as an optimal in silico neuropharmacokinetic profile. From a therapeutic perspective, merging key pharmacophoric features from memantine and M30D provides a new medicinal scaffold with dual-/multifunctional properties and human plasma stability for the future development of potential drugs for treating AD.

Instability Mechanism of Osimertinib in Plasma and a Solving Strategy in the Pharmacokinetics Study.

Osimertinib is a third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) and a star medication used to treat non-small-cell lung carcinomas (NSCLCs). It has caused broad public concern that osimertinib has relatively low stability in plasma. We explored why osimertinib and its primary metabolites AZ-5104 and AZ-7550 are unstable in rat plasma. Our results suggested that it is the main reason inducing their unstable phenomenon that the Michael addition reaction was putatively produced between the Michael acceptor of osimertinib and the cysteine in the plasma matrix. Consequently, we identified a method to stabilize osimertinib and its metabolite contents in plasma. The assay was observed to enhance the stability of osimertinib, AZ-5104, and AZ-7550 significantly. The validated method was subsequently applied to perform the pharmacokinetic study for osimertinib in rats with the newly established, elegant, and optimized ultra-performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) strategy. The assay was assessed for accuracy, precision, matrix effects, recovery, and stability. This study can help understand the pharmacological effects of osimertinib and promote a solution for the similar problem of other Michael acceptor-contained third-generation EGFR-TKI.

Application of LEDA algorithm for the recognition of P-glycoprotein and Carbonic Anhydrase hybrid inhibitors and evaluation of their plasma stability by HPLC-MS/MS analysis.

Design and synthesis of new candidate drugs produces a large number of compounds that must be qualified and tested to evaluate their characteristics and potential applications. Therefore, many studies will be scheduled and, consequently, it will be necessary to arrange specific, reliable, fast and relatively cheap analytic methods to support this research. The manuscript proposes a new approach in the HPLC-MS/MS analysis by using a sole chromatographic set up, tuned to minimize the run time, without requiring high efficiency or resolution between the analytes. The chromatographic column was used only to avoid or limit the interference of sample matrix towards the analyte ionization process (matrix-effects). Then, the MS/MS properties were explored to solve the signal assignment, by performing a series of energy resolved experiments to optimize the parameters and applying an interesting post-processing data elaboration tool (LEDA). The reliability of the new approach was evaluated in a chemical stability study in PBS and human plasma samples of a series of isomeric compounds P-glycoprotein/Carbonic Anhydrase (P-gp/CA) hybrid inhibitors. The obtained results demonstrated the effectiveness (reliability 97%-100%) of the LEDA algorithm to recognize and to separate the possible isomers present in the samples. The obtained matrix-effects values (ME 96%-106%) established that the chromatographic set up (short column and fast elution gradient) was proper to avoid the matrix interferences, while recovery values (RE 88%-108%) indicate a suitable sample preparation, despite only a protein precipitation was carried out. The quantitative performances of proposed HPLC-MS/MS methods showed an accuracy ranging between 92% and 108% and a precision lower than 13% that allows to be confident on the determination of new P-gp/CA hybrid inhibitors in the degradation study. Therefore, the general procedure proposed was found adequate to study a series of isomeric compounds without their chromatographic separation but only by applying and developing the MS/MS features.

Biotinylated peptides substituted with D-amino acids with high stability as anti-anaphylactic agents targeting platelet-activating factor.

Platelet-activating factor (PAF) is an important lipid mediator of anaphylaxis and therefore can be an anti-anaphylactic agent target. Recently, we reported that several synthetic biotinylated peptides containing a Tyr-Lys-Asp-Gly sequence markedly inhibited the bioactivities of PAF in vitro and in vivo; it also inhibited anaphylactic reactions such as hypothermia, hypotension, and vascular permeability in vivo. Here, we report the anti-anaphylactic effects of three biotinylated heptapeptides (peptide 1: H-Lys(biotinyl)-Trp-Tyr-Lys-Asp-Gly-Asp-OH, peptide 2: H-D -Lys(biotinyl)-Trp-Tyr-Lys-Asp-Gly-Asp-OH, and peptide 3: H-D -Lys(biotinyl)-Trp-Tyr-Lys-Asp-Gly-D -Asp-OH). The experiment using tryptophan fluorescence spectroscopy showed that the interaction of peptides 2 and 3 with PAF was larger than that of peptide 1. Experiments using a rat model of hind paw edema showed that peptides 1, 3, and 2 inhibited PAF-induced edema by 67.9%, 69.3%, and 79.3%, respectively. In a mouse model of anaphylaxis, both peptides 2 and 3 showed inhibitory effects on anaphylactic hypothermia, whereas peptide 1 did not. Furthermore, experiments involving in vitro rat plasma stability of peptides showed that both peptides 3 and 2 were more stable in plasma compared to peptide 1 (84.0%, 51.8%, and 0%, remained after 6 h, respectively). Our results suggest that both peptides 2 and 3 may show systemic and local inhibitory effects as anti-anaphylactic agents targeting PAF.

Transport, Stability, and In Vivo Hypoglycemic Effect of a Broccoli-Derived DPP-IV Inhibitory Peptide VPLVM.

Diabetes is a major metabolic disease that requires long-term pharmacotherapy. Bioactive peptides have unique advantages such as higher potency, selectivity, and safety over small molecules and have achieved great success in the treatment of diabetes. We previously isolated a dipeptidyl peptidase-IV (DPP-IV) inhibitory peptide VPLVM with IC50 = 99.68 µM from the protein hydrolysates of broccoli stems and leaves. Here, we evaluated the interaction with DPP-IV, transport, stability, and in vivo hypoglycemic effects of VPLVM. VPLVM interacted closely and steadily with DPP-IV at S1 and S2 pockets. VPLVM had a good gastrointestinal enzyme resistance and was transported through the Caco-2 cell monolayer via paracellular diffusion and by the PepT1 with a Papp of 6.96 × 10-7 cm/s. VPLVM has a t1/2 of 12.56 ± 0.41 min in vitro plasma stability. In the oral glucose tolerance test, VPLVM showed an excellent hypoglycemic effect at 30 min after administration. VPLVM has potential as a candidate for the treatment of hyperglycemia.

Neuropeptide B/W receptor 1 peptidomimetic agonists: Structure-activity relationships and plasma stability.

Neuropeptides B and W (NPB and NPW) are endogenous ligands of the Neuropeptide B/W Receptor 1 (NPBWR1) which has been implicated in a wide range of functions including regulation of pain and energy homeostasis. There is currently little information on the structure-activity relationships (SAR) of these two neuropeptides. In a quest to develop stable and potent NPBWR1 peptidomimetic agonists, we performed systematic SAR by truncation, Alanine/Glycine and d-amino acid scans, and replacement with unnatural amino acids. Evaluation in the NPBWR1 calcium assay revealed that the C-terminal GRAAGLL and N-terminal WYK regions constitute the two-epitope pharmacophore for NPBWR1 agonism. Replacement of the N-terminal Trp with its desaminoTrp residue resulted in compound 30 which exhibited nanomolar potency comparable to the endogenous NPB at NPBWR1 (Calcium assay: EC50 = 8 nM vs. 13 nM, cAMP assay: 2.7 nM vs 3.5 nM) and enhanced metabolic stability against rat plasma (39.1 min vs. 11.9 min).

Interspecies comparison of plasma metabolism and sample stabilization for quantitative bioanalyses: Application to (R)-CE3F4 in preclinical development, including metabolite identification by high-resolution mass spectrometry.

The CE3F4 is an inhibitor of the type 1 exchange protein directly activated by cAMP (EPAC1), which is involved in numerous signaling pathways. The inhibition of EPAC1 shows promising results in vitro and in vivo in different cardiac pathological situations like hypertrophic signaling, contributing to heart failure, or arrhythmia. An HPLC-UV method with a simple and fast sample treatment allowed the quantification of (R)-CE3F4. Sample treatment consisted of simple protein precipitation with 50 µL of ethanol and 150 µL of acetonitrile for a 50 µL biological sample. Two wavelengths were used according to the origin of plasma (220 or 250 nm for human samples and 250 nm for murine samples). Accuracy profile was evaluated for both wavelengths, and the method was in agreement with the criteria given by the EMA in the guideline for bioanalytical method validation for human and mouse plasma samples. The run time was 12 min allowing the detection of the (R)-CE3F4 and a metabolite. This study further permitted understanding the behavior of CE3F4 in plasma by highlighting an important difference between humans and rodents on plasma metabolism and may impact future in vivo studies related to this molecule and translation of results between animal models and humans. Using paraoxon as a metabolism inhibitor was crucial for the stabilization of (R)-CE3F4 in murine samples. HPLC-UV and HPLC-MS/MS studies were conducted to confirm metabolite structure and consequently, the main metabolic pathway in murine plasma.

Novel O-[11C]-methylated derivatives of the neprilysin inhibitor sacubitril: Radiosynthesis, autoradiography and plasma stability evaluation.

INTRODUCTION: The O-[11C]methylated derivatives of the clinically used neprilysin inhibitor (NEPi) sacubitril ([11C]SacOMe, (2R,4S)-ethyl 5-([biphenyl]-4-yl)-4-(4-[11C]methoxy-4-oxobutanamido)-2-methylpentanoate) and LBQ657 ([11C]MeOLBQ, (2R,4S)-5-(biphenyl-4-yl)-4-[(3-carboxypropionyl)amino]-2-methylpentanoic acid [11C]methyl ester and [11C]LBQOMe, (2R,4S)-5-(biphenyl-4-yl)-4-[(4-[11C]methoxy-4-oxobutanamido)]-2-methylpentanoic acid) were evaluated to determine their potential as PET imaging tracers and investigate the effect of such labeling esterification on neprilysin (NEP) binding. METHODS: [11C]MeOLBQ, [11C]SacOMe and [11C]LBQOMe were synthesized by O-[11C]methylation using [11C]methyl triflate. Binding of these radiolabeled derivatives (5 nM) were assessed by autoradiography on rat neprilysin rich kidney slices with or without 10 µM NEPi (thiorphan or sacubitril) for 20 min at 37 °C. [11C]LBQOMe was further tested for binding selectivity in the presence of 10 µM of angiotensin-converting enzyme inhibitor (ACEi, captopril) or angiotensin II AT1 receptor blocker (AT1R, losartan). Radioligands were evaluated for their in vitro stability up to 20 min after incubation at 37 °C in rat and human plasma by reverse-phase column-switch HPLC. Non-radioactive SacOMe incubated in rat and human plasma was analyzed by HPLC-coupled with high resolution mass spectrometry (HRMS) to confirm the metabolites' identity. [11C]SacOMe main labeled metabolite was further analyzed by HPLC after incubation in rat kidney slices at 37 °C. RESULTS: The novel [11C]SacOMe and [11C]LBQOMe were produced in 32 ± 3% RCY and 15 ± 6% at EOS (decay-corrected from [11C]CO2, n = 3), high molar activity (407 ± 92 GBq/µmol and 260 ± 92 GBq/µmol), and high chemical (≥90%) and radiochemical (≥99%) purities in a total synthesis time of 31 and 34 min, respectively. High accumulation of [11C]SacOMe and [11C]LBQOMe in kidneys was completely blocked (>99.9%) by pre-incubation with NEPi, whereas [11C]MeOLBQ displayed negligible uptake in autoradiography studies. [11C]LBQOMe binding was not affected by saturating doses of losartan or captopril indicating binding selectivity for NEP. While [11C]SacOMe and [11C]LBQOMe were stable in human plasma (>92%) even after 20 min incubation at 37 °C, rat plasma analyses exhibited >95% biotransformation of [11C]SacOMe, 40% of [11C]LBQOMe and >80% loss of the 11C-methyl group of [11C]MeOLBQ after 5 min of incubation. Comparable results using the non-radioactive SacOMe were obtained by HPLC-HRMS. Radio-HPLC analysis of the extracted activity of rat kidney slices incubated with [11C]SacOMe demonstrated that >95% of the radioactive signal corresponded to [11C]LBQOMe as the main metabolite. CONCLUSION: The desethyl active metabolite of [11C]SacOMe, [11C]LBQOMe, displayed stability in human plasma, binding selectivity for neprilysin over ACE or AT1R in rat kidney slices. Rapid plasmatic dealkylation at the 2-methylbutanoic acid position is in line with the necessity of incorporating the labeling group on oxobutanoic acid side in the strategy to develop a stable O-alkylated labeled derivative of sacubitril.

Multifunctional Enkephalin Analogs with a New Biological Profile: MOR/DOR Agonism and KOR Antagonism.

In our previous studies, we developed a series of mixed MOR/DOR agonists that are enkephalin-like tetrapeptide analogs with an N-phenyl-N-piperidin-4-ylpropionamide (Ppp) moiety at the C-terminus. Further SAR study on the analogs, initiated by the findings from off-target screening, resulted in the discovery of LYS744 (6, Dmt-DNle-Gly-Phe(p-Cl)-Ppp), a multifunctional ligand with MOR/DOR agonist and KOR antagonist activity (GTPγS assay: IC50 = 52 nM, Imax = 122% cf. IC50 = 59 nM, Imax = 100% for naloxone) with nanomolar range of binding affinity (Ki = 1.3 nM cf. Ki = 2.4 nM for salvinorin A). Based on its unique biological profile, 6 is considered to possess high therapeutic potential for the treatment of chronic pain by modulating pathological KOR activation while retaining analgesic efficacy attributed to its MOR/DOR agonist activity.

The effect of structural modification of antimicrobial peptides on their antimicrobial activity, hemolytic activity, and plasma stability.

In this article, a series of modifications were made on an antimicrobial peptide F2,5,12 W, including altering the amino acid sequence, introducing cysteine and other typical amino acids, developing peptide dimers via disulfide bonds, and conjugating with mPEG, in order to enhance the antimicrobial activity, plasma stability, and reduce the hemolytic activity of peptides. The results showed that mPEG conjugation could significantly improve the plasma stability and reduce the hemolytic activity of peptides, while the antimicrobial activity decreased meanwhile. However, altering the sequence of the peptide without changing its amino acid composition had little impact on its antimicrobial activity and plasma stability. The introduction of cysteine enhanced the plasma stability of peptides conspicuously, but at the same time, the increased hydrophobicity of peptides increased their hemolysis. The antimicrobial mechanism and cytotoxicity of the peptides with relatively high antimicrobial activity were also studied. In general, this study provided some ideas for the rational design and structure optimization of antimicrobial peptides.

A new analogue of islet neogenesis associated protein with higher structural and plasma stability.

Islet Neogenesis Associated Protein pentadecapeptide (INGAP-PP) increases ß-cell mass and function in experimental animals. A short clinical trial also yielded promising results. However, HTD4010, a new peptide derived from INGAP-PP, was developed in order to optimize its specific effects by minimizing its side effects. To study and compare the tertiary structure, stability dynamics, and plasma stability of HTD4010, an INGAP-PP analogue. Both peptides were pre-incubated in human, rat and mouse plasma at 37 °C, and their presence was identified and quantified by high performance liquid chromatography at different time-points. GROMACS 2019 package and the Gromos 54A7 force field were used to evaluate overall correlated motion of the peptide molecule during molecular dynamics simulation by essential dynamics. HTD4010 exhibited significantly larger plasma stability than INGAP-PP, and its structural stability was almost 3.36-fold higher than INGAP-PP. These results suggest that HTD4010 may facilitate longer tissue interaction, thereby developing higher potential biological effects. If so, HTD4010 may become a promising therapeutic agent to treat people with diabetes. Communicated by Ramaswamy H. Sarma.

Assessment of the Physicochemical Properties and Stability for Pharmacokinetic Prediction of Pyrazinoic Acid Derivatives.

BACKGROUND: Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis, which still has high prevalence worldwide. In addition, cases of drug resistance are frequently observed. In the search for new anti-TB drugs, compounds with antimycobacterial activity have been developed, such as derivatives of pyrazinoic acid, which is the main pyrazinamide metabolite. In a previous study, the compounds were evaluated and showed moderate antimycobacterial activity and no important cytotoxic profile; however, information about their pharmacokinetic profile is lacking. OBJECTIVE: The aim of this work was to perform physicochemical, permeability, and metabolic properties of four pyrazinoic acid esters. METHOD: The compounds were analyzed for their chemical stability, n-octanol:water partition coefficient (logP) and apparent permeability (Papp) in monolayer of Caco-2 cells. The stability of the compounds in rat and human microsomes and in rat plasma was also evaluated. RESULTS: The compounds I, II and IV were found to be hydrophilic, while compound III was the most lipophilic (logP 1.59) compound. All compounds showed stability at the three evaluated pHs (1.2, 7.4 and 8.8). The apparent permeability measured suggests good intestinal absorption of the compounds. Additionally, the compounds showed metabolic stability under action of human and rat microsomal enzymes and stability in rat plasma for at least 6 hours. CONCLUSION: The results bring favorable perspectives for the future development of the evaluated compounds and other pyrazinoic acid derivatives.

Synthetic Analogues of Aminoadamantane as Influenza Viral Inhibitors-In Vitro, In Silico and QSAR Studies.

A series of nineteen amino acid analogues of amantadine (Amt) and rimantadine (Rim) were synthesized and their antiviral activity was evaluated against influenza virus A (H3N2). Among these analogues, the conjugation of rimantadine with glycine illustrated high antiviral activity combined with low cytotoxicity. Moreover, this compound presented a profoundly high stability after in vitro incubation in human plasma for 24 h. Its thermal stability was established using differential and gravimetric thermal analysis. The crystal structure of glycyl-rimantadine revealed that it crystallizes in the orthorhombic Pbca space group. The structure-activity relationship for this class of compounds was established, with CoMFA (Comparative Molecular Field Analysis) 3D-Quantitative Structure Activity Relationships (3D-QSAR) studies predicting the activities of synthetic molecules. In addition, molecular docking studies were conducted, revealing the structural requirements for the activity of the synthetic molecules.

Cyclodextrin Complexation for Enhanced Stability and Non-invasive Pulmonary Delivery of Resveratrol-Applications in Non-small Cell Lung Cancer Treatment.

Pulmonary drug delivery is a noninvasive therapeutic approach that offers many advantages including localized drug delivery and higher patient compliance. As with all formulations, the low aqueous solubility of a drug often poses a challenge in the formulation development. Thus, strategies such as cyclodextrin (CD) complexation have been utilized to overcome this challenge. Resveratrol (RES), a natural stilbene, has shown abundant anti-cancer properties. Due to many drawbacks of conventional chemotherapeutics, RES has been proposed as an emerging alternative with promising pharmacological effects. However, RES has limited therapeutic applications due to low water solubility, chemical stability, and bioavailability. This study was aimed at developing an inhalable therapy that would increase the aqueous solubility and stability of RES by complexation with sulfobutylether-ß-cyclodextrin (SBECD). Phase solubility profiles indicated an optimal stoichiometric inclusion complex at 1:1 (SBECD:RES) ratio for formulation considerations. Physiochemical characterizations were performed to analyze CD-RES. Stability studies at pH 7.4 and in plasma indicated significant improvement in RES stability after complexation, with a much longer half-life. The mass median aerodynamic diameter (MMAD) of CD-RES was 2.6 ± 0.7 µm and fine particle fraction (FPF) of 83.4 ± 3.0% are suitable for pulmonary delivery and efficient deposition. Lung cancer was selected as the respiratory model disease, owing to its high relevance as the major cause of cancer deaths worldwide. Cell viability studies in 5 non-small-cell-lung-cancer (NSCLC) cell lines suggest CD-RES retained significant cytotoxic potential of RES. Taken together, CD-RES proves to be a promising inhalation treatment for NSCLC.