A Highly Efficient Strategy for One-Pot and Pseudo-Six-Component Synthesis of Hexahydroquinolines.

In this study, a homogeneous acid-catalyzed reaction of a series of benzaldehydes, benzylamines, and Meldrum's acid was presented, allowing the novel one-pot and multicomponent synthesis of hexahydroquinolines with high stereoselectivity. The current strategy has advantages including high regioselectivity, good efficiency, reasonable diversity, utilization of an inexpensive and safe catalyst, and easy purification of products by simple recrystallization. The current reaction utilizes 2 equiv of Meldrum's acid, 3 equiv of benzaldehyde derivatives, and one equiv of amine derivatives to yield (4'S,5'S,7'S)-1'-benzyl-2,2-dimethyl-4',5',7'-triphenyl-3',4',7',8'-tetrahydro-1'H-spiro[[1,3]dioxane-5,6'-quinoline]-2',4,6(5'H)-trione derivatives.

Rational peptide design for targeting cancer cell invasion.

Cell invasion is an important process in cancer progression and recurrence. Invasion and implantation of cancer cells from their original place to other tissues, by disabling vital organs, challenges the treatment of cancer patients. Given the importance of the matter, many molecular treatments have been developed to inhibit cancer cell invasion. Because of their low production cost and ease of production, peptides are valuable therapeutic molecules for inhibiting cancer cell invasion. In recent years, advances in the field of computational biology have facilitated the design of anti-cancer peptides. In our investigation, using computational biology approaches such as evolutionary analysis, residue scanning, protein-peptide interaction analysis, molecular dynamics, and free energy analysis, our team designed a peptide library with about 100 000 candidates based on A6 (acetyl-KPSSPPEE-amino) sequence which is an anti-invasion peptide. During computational studies, two of the designed peptides that give the highest scores and showed the greatest sequence similarity to A6 were entered into the experimental analysis workflow for further analysis. In experimental analysis steps, the anti-metastatic potency and other therapeutic effects of designed peptides were evaluated using MTT assay, RT-qPCR, zymography analysis, and invasion assay. Our study disclosed that the IK1 (acetyl-RPSFPPEE-amino) peptide, like A6, has great potency to inhibit the invasion of cancer cells.

Synthetic Small Molecules Induce Insulin Secretion and Pancreatic Beta-Cell-Specific Gene Expression.

Despite various efficient pharmaceuticals which are already used to manage diabetes, new drugs are needed to preserve and restore the function of pancreatic ß-cells (pßCs) including cell-specific gene expression and insulin production and secretion. Newly developed small molecules (SMs) with potential anti-diabetic activity need to be preliminarily tested. Mice insulinoma MIN6 cells can be utilized as an in vitro screening model. These cells have pßC characteristics and can secrete insulin in response to glucose level changes. As well, the ß-cell-specific gene expression pattern of these cells is similar to that of mouse pancreatic islet cells. It is possible to use this cell line as a research tool to study the function of pßCs. To date, approximately 60 genes have been identified which are effective in the pßC embryonic development and insulin production and secretion during puberty, including pancreas/duodenum homeobox protein 1 (Pdx1), neuronal differentiation 1 (Neurod1), neurogenin3 (Ngn3), and insulin-1 precursor (Ins1). In this study, a family of new SMs that are structurally similar to glinides was synthesized through 3 different synthetic methods and categorized into 3 categories (C1-C3). Then, these novel SMs were characterized by testing their effects on cell viability, pßC-specific gene expression, and insulin secretion in MIN6 in 4 different concentrations and at 3 time points (24, 48, and 72 h). According to our results, SMs of C1 (1j, 1k, and 1l) and 2 SMs of C3 (1f, 1i), at 200 µM concentration, were able to increase the expression levels of Pdx1, Neurod1, Ngn3, and Ins1 as well as the insulin secretion after 24 h. However, C2 (1a, 1b, 1c, and 1d) did not show significant bioactivity of MIN6 cells. These investigated molecules can provide a tool for exploring pseudo-islet functionality in MIN6 cells or provide a possible basis for future therapeutic interventions for diabetes.

Synergies in antimicrobial treatment by a levofloxacin-loaded halloysite and gold nanoparticles with a conjugation to a cell-penetrating peptide.

Herein, a novel designed antimicrobial therapeutic drug delivery system is presented, in which halloysite nanotubes (HNTs) encapsulate a determined dosage of levofloxacin (lvx). Moreover, gold nanoparticles (AuNPs) have been embedded into the structure for plasmonic heating under irradiation of the green LED light (7 W, 526 nm). It was revealed that the plasmonic heating of the AuNPs leads to a controlled trend in the lvx release process. Also, a synergistic effect on the antimicrobial activity of the prepared therapeutic system has been observed through photothermal heating of the structure. To enhance the cell adhesion, a cell-penetrating peptide sequence (CPP) is conjugated to the surfaces. This CPP has led to quick co-localization of the prepared nano-cargo (denoted as lvx@HNT/Au-CPP) with the bacterial living cells and further attachment (confirmed by confocal microscopy). Concisely, the structure of the designed nano-cargo has been investigated by various methods, and the in vitro cellular experiments (zone of inhibition and colony-counting) have disclosed that the antimicrobial activity of the lvx is significantly enhanced through incorporation into the HNT/Au-CPP delivery system (drug content: 16 wt%), in comparison with the individual lvx with the same dosage. Hence, it can be stated that the bacterial resistance against antibiotics and the toxic effects of the chemical medications are reduced through the application of the presented strategy.

A patent review on efficient strategies for the total synthesis of pazopanib, regorafenib and lenvatinib as novel anti-angiogenesis receptor tyrosine kinase inhibitors for cancer therapy.

Angiogenesis is an important and interesting scientific subject in the area of malignant tumours. Current research importance and interest are directed in connection to blood microvessels in cancer cell proliferation, tumour growth, and metastasis. Tyrosine kinases have been intensely implicated as therapeutic targets that affect the angiogenic process in tumour growth. In the last decades, targeting angiogenesis has led to achievements in the therapy of different carcinomas by different mechanisms, such as the utilization of anti-angiogenic small molecule receptor tyrosine kinase inhibitors. In the current review, we aim to track the advancements in the total synthesis of three receptor tyrosine kinase inhibitors (pazopanib, regorafenib and lenvatinib). This review surveys different synthetic routes for these three approved drugs (pazopanib, regorafenib and lenvatinib) which were previously published as patents (2014-2021). The purity of medicines is a very important factor during manufacturing so we have decided to review the purification process of these anticancer medicines as well. It should be noted that the different patents may have reported some procedures with different yields and purities for the synthesis of desired drug and their intermediates. In order to simplify the understanding of the contents of this review article, only the best results reported in each of these patents are reported for the synthesis of desired drug and their intermediates.

Highly selective fluorescent peptide-based chemosensors for aluminium ions in aqueous solution.

Two novel fluorescent peptide-based chemosensors, including A (2-amino-benzoyl-Ser-Glu-Glu-NH2) and B (2-amino-benzoyl-Ala-Glu-Pro-Glu-Ala-Glu-Pro-NH2) were synthesized and characterized by nuclear magnetic resonance (NMR) spectra. These fluorescent probes exhibited excellent selective and sensitive responses to Al3+ ions over other metal ions in aqueous buffered solutions. The limits of detection for both chemosensors towards the Al3+ ions were in the order of ∼10-7 M (A: 155 nM and B: 195 nM), which clearly indicates that these probes have significant potential for biological applications. They also displayed high binding affinity (1.3029 × 104 M-1 and 1.7586 × 104 M-1 relevant to A and B respectively). These two chemosensors are great analytical probes that produce turn-on responses upon binding to Al3+ ions through an intramolecular charge transfer (ICT) mechanism. In addition, the application of both chemosensors was examined over a wide range of pH. The fluorescent peptide-based probes and Al3+ form a 1:1 coordination complex according to the ESI-MS and Job's plot analysis. Notably, upon addition of Al3+ to these chemosensors, a fluorescence enhancement of approximately 8-fold was observed and the binding mode was determined using NMR titration and fluorescence emission data.

Potential anticancer activity of a new pro-apoptotic peptide-thioctic acid gold nanoparticle platform.

Targeted nanoparticle platforms designed to induce cell death by apoptosis can bypass the resistance mechanisms of cancer cells. With this in mind we have constructed a new cancer-targeting peptide-functionalized nanoparticle using gold nanoparticles (AuNPs) and a thioctic acid-DMPGTVLP peptide (TA-peptide) conjugate. Morphological analysis of the nanoparticles by transmission electron microscopy showed average diameters of about 3.52 nm and 26.2 nm for the AuNP core and shell, respectively. Strong affinity toward the nucleolin receptors of breast cancer cell lines MCF-7 and T47D was observed for the TA-peptide gold nanoparticles (TAP@AuNPs) based on IC50 values. Furthermore, the nanoparticles showed excellent hemocompatibility. Quantitative results of atomic absorption showed improved uptake of TAP@AuNPs. Treatment of the cells with TAP@AuNPS resulted in greater release of cytochrome c following caspase-3/7 activation compared with free TA-peptide. The cytosolic level of adenosine triphosphate for TAP@AuNPs was higher than in controls. Higher anti-tumor efficiency was observed for TAP@AuNPs than TA-peptide compared with phosphate-buffered saline after intratumoral injection in tumor-bearing mice. It can be concluded that the design and development of a receptor-specific peptide-AuNP platform will be valuable for theranostic applications in cancer nanomedicine.

Polydopamine-functionalized magnetic iron oxide for the determination of trace levels of lead in bovine milk.

In this work, a novel sorbent based on polydopamine-functionalized magnetic ferric oxide (Fe3O4) was synthesized and applied for dispersive solid phase extraction of Pb(II) in bovine milk samples. The extracts were analyzed by flame atomic absorption spectrometry (FAAS). The sorbent was characterized with different analytical techniques (XRD, FT-IR, SEM, TEM, VSM and EDX). To reach the maximum extraction efficiency of Pb(II), some effective parameters on both adsorption and desorption steps were optimized with the aid of central composite design and response surface methodology. Under the optimal conditions, the method provided an enhancement factor of 40.5 corresponding to the absolute recovery of 81%. LOD and LOQ were found as 0.13 and 0.43 ng mL-1, respectively. The calibration curve was linear over the concentration range of 3.0-300 ng mL-1 (R2 = 0.9957). The intra and inter-day precisions (RSD%) of the method were calculated as 3.2% and 5.6%, respectively. Finally, the method was successfully applied for the determination of Pb(II) in different bovine milk samples. The Pb(II) content in one of the investigated milk samples was found to exceed the maximum permissible limit (20 µg L-1) set by Codex Alimentarius Commission. The relative recoveries were obtained within the range of 86.5-93.6.

Curcumin-loaded nanoliposomes linked to homing peptides for integrin targeting and neuropilin-1-mediated internalization.

CONTEXT: Curcumin, a naturally occurring polyphenol, has been extensively studied for its broad-spectrum anticancer effects. The potential benefits are, however, limited due to its poor water solubility and rapid degradation which result in low bioavailability on administration. OBJECTIVES: This study encapsulates curcumin in nanoliposomes including an integrin-homing peptide combined with a C end R neuropilin-1 targeting motif for targeted delivery and receptor-mediated internalization, respectively. MATERIALS AND METHODS: The linear GHHNGR (Glycine-Histidine-Histidine-Asparagine-Glycine-Arginine) was synthesized through F-moc chemistry on 2-chlorotrityl chloride resin and conjugated to oleic acid. The lipoyl-peptide units were then co-assembled with lecithin and 0-75 mole % Tween-80 into liposomes. Curcumin was passively entrapped using a film hydration technique and its degradation profile was examined within seven consecutive days. The cytotoxic effects of the curcumin-loaded liposomes were studied on MCF-7 and MDA-MB-468, during 24 h exposure in MTT assay. RESULTS: The maximum curcumin entrapment (15.5% W/W) and minimum degradation (< 23%) were obtained in a pH switch loading method from 5.7 to 8, in nanoliposomes (< 50 nm) containing oleyl-peptide, lecithin and Tween-80 (1:1:0.75 mole ratio). The oleyl-peptide did not prove any haemolytic activity (< 1.5%) up to 10-fold of its experimental concentration. The curcumin-loaded liposomes displayed significant reduction in the viabilities of MCF-7 (IC50 3.8 µM) and MDA-MB-468 (IC50 5.4 µM). DISCUSSION AND CONCLUSION: This study indicated potential advantages of the peptide-conjugated liposomes in drug transport to the cancer cells. This feature might be an outcome of probable interactions between the targeted nanoliposomes with the integrin and neuropilin-1 receptors.

Synthesis and Biological Evaluation of Cyclic [99mTc]-HYNIC-CGPRPPC as a Fibrin-Binding Peptide for Molecular Imaging of Thrombosis and Its Comparison with [99mTc]-HYNIC-GPRPP.

PURPOSE: Many patients worldwide suffer from cardiovascular diseases for which an underlying factor is thrombosis. Devising a molecular imaging technique for early detection of thrombosis in a clinical setting is highly recommended. Because fibrin is a major constituent of clots and is present in all types of thrombi but absent in circulation, it is a highly specific and sensitive target for molecular imaging of thrombi. It is assumed that cyclization of peptides will improve the receptor binding affinity and stability of the peptide. In the present study, we have developed linear and cyclic fibrin-binding peptides for thrombus imaging and compared their biological properties. PROCEDURES: Linear HYNIC-GPRPP and cyclic HYNIC-CGPRPPC peptides were synthesized using a standard Fmoc strategy and radiolabeled with Tc-99m. The stability of the radiolabeled peptides in human plasma and their affinity for fibrin and blood clots were determined. Blood clearance and biodistribution were evaluated in rats and mice, respectively. The peptide with the highest affinity was injected to a live rabbit femoral thrombosis model, and scintigraphic images were obtained. RESULTS: In vitro studies show that peptides are stable in human plasma and have a high affinity for human fibrin. They also demonstrated fast blood clearance in rats and high thrombus uptake in the Balb/c mice femoral thrombosis model. Femoral thrombosis was visualized 30 min postinjection of cyclic peptide in a live rabbit model using single photon emission computed tomography (SPECT)/X-ray computed tomography. CONCLUSIONS: The results indicate that the cyclic peptide is a promising agent for molecular imaging of fibrin using SPECT.

Toxicity of serum albumin on microglia upon seeding effect of amyloid peptide.

We demonstrate in vitro cross-seeding of bovine serum albumin (BSA) in the presence of Aß25-35 and their cytotoxic effects on microglial cells. To investigate the cross-seeding of BSA in the presence of Aß25-35 fibrils, we examined how Aß25-35 fibrils can function as seeds to trigger and accelerate BSA fibrillogenesis using ThT, intrinsic fluorescence, ANS fluorescence and transmission electron microscopy (TEM). Moreover, the effects of these fibrils on microglial viability were measured using MTT and Annexin V/propidium iodide (PI) staining. Although Aß25-35 is toxic against microglia, it acted as seed and affected the aggregation pathway and accelerated the fibrillogenesis of BSA in vitro, resulted in an enhanced cytotoxic effect in comparison with Aß25-35 or BSA alone. These observations thought to be helpful to understand the molecular mechanism of enhanced toxicity due to the coexistence of the aggregation prone proteins/peptides,. then cross-seeding effect on microglial cells that may involve in neurodegenerative diseases such as Alzheimer's disease (AD).

Synthesis of functionalized pseudopeptides through five-component sequential Ugi/nucleophilic reaction of N-substituted 2-alkynamides with hydrazides.

Five-component sequential Ugi/nucleophilic addition reaction of aromatic aldehydes, primary amines, propiolic acid, isocyanides, and hydrazides has been developed in order to access polyfunctional pseudopeptides. The reaction may proceed through formation of N-substituted 2-alkynamides as intermediates. This process is found to be mild and operationally simple with broad substrate scope.