Cytotoxic Potential of Novel Quinoline Derivative: 11-(1,4-Bisaminopropylpiperazinyl)5-methyl-5H-indolo[2,3-b]quinoline against Different Cancer Cell Lines via Activation and Deactivation of the Expression of Some Proteins.

The current study evaluated the cytotoxic activity of 11-(1,4-bisaminopropylpiperazinyl)5-methyl-5H-indolo[2,3-b]quinoline (BAPPN), a novel derivative of 5-methyl-5H-indolo[2,3-b]quinoline, against hepatocellular carcinoma (HepG2), colon carcinoma (HCT-116), breast (MCF-7), and lung (A549) cancer cell lines and the possible molecular mechanism through which it exerts its cytotoxic activity. BAPPN was synthesized and characterized with FT-IR and NMR spectroscopy. The binding affinity scores of BAPPN for caspase-3 PDB: 7JL7 was -7.836, with an RMSD of 1.483° A. In silico screening of ADME properties indicated that BAPPN showed promising oral bioavailability records in addition to their high gastrointestinal absorption and blood-brain barrier penetrability. BAPPN induced cytotoxicity, with IC50 values of 3.3, 23, 3.1, and 9.96 µg/mL against cancer cells HepG2, HCT-116, MCF-7, and A549, respectively. In addition, it induced cell injury and morphological changes in ultracellular structure, including cellular delayed activity, vanishing of membrane blebbing, microvilli, cytoplasmic condensation, and shrunken nucleus with more condensed chromatin autophagosomes. Furthermore, BAPPN significantly increased the protein expression of caspase-3 and tumor suppressor protein (P53). However, it significantly reduced the secretion of vascular endothelial growth factor (VEGF) protein into the medium and decreased the protein expression of proliferation cellular nuclear antigen (PCNA) and Ki67 in HepG2, HCT-116, MCF-7, and A549 cells. This study indicates that BAPPN has cytotoxic action against liver, colon, breast, and lung cancer cell lines via the up-regulation of apoptotic proteins, caspase-3 and P53, and the downregulation of proliferative proteins, VEGF, PCNA, and Ki67.

Synthesis, biological evaluation and molecular modelling of 3-Formyl-6-isopropylchromone derived thiosemicarbazones as α-glucosidase inhibitors.

Type-2 Diabetes Mellitus (T2DM) is one of the most common metabolic disorders in the world and over the past three decades its incidence has increased drastically. α-Glucosidase inhibitors are used to control the hyperglycemic affect of T2DM. Herein, we report the synthesis, α-glucosidase inhibition, structure activity relationship, pharmacokinetics and docking analysis of various novel chromone based thiosemicarbazones 3(a-r). The derivatives displayed potent activity against α-glucosidase with IC50 in range of 0.11 ± 0.01-79.37 ± 0.71 µM. Among all the synthesized compounds, 3a (IC50 = 0.17 ± 0.026 µM), 3 g (IC50 = 0.11 ± 0.01 µM), 3n (IC50 = 0.55 ± 0.02 µM), and 3p (IC50 = 0.43 ± 0.025 µM) displayed higher inhibitory activity as compared to the standard, acarbose. Moreover, we have developed a statistically significant 2D-QSAR model (R2tr:0.9693; F: 50.4647 and Q2LOO:0.9190), which can be used in future to further design potent thiosemicarbazones as inhibitors of α-glucosidase.

Design and cytotoxic evaluation via apoptotic and antiproliferative activity for novel 11(4-aminophenylamino)neocryptolepine on hepatocellular and colorectal cancer cells.

The current study evaluated the cytotoxic activity of 11(4-Aminophenylamino)neocryptolepine (APAN), a novel derivative of neocryptolepine, on hepatocellular (HepG2) and colon (HCT-116) carcinoma cell lines as well as, the possible molecular mechanism through which it exerts its cytotoxic activity. The APAN was synthesized and characterized based on their spectral analyses. Scanning for anticancer target of APAN by Swiss software indicated that APAN had highest affinity for protein tyrosine kinase 6 enzyme. Furthermore, Super pred software indicated that APAN can be indicated in hepatic and colorectal cells with 92%. Molecular docking studies indicated that the binding affinity scores of APAN for protein PDB code: 6CZ4 of tyrosine kinase 6 recorded of - 6.6084 and RMSD value of 0.8891°A, while that for protein PDB: 7JL7 of caspase 3 was - 6.1712 and RMSD of 0.8490°A. Treatment of HepG2 and HCT-116 cells with APAN induced cytotoxicity with IC50 of 2.6 and 1.82 µg/mL respectively. In addition, it induced injury and serious morphological changes in cells including, disappearance of microvilli, membrane blebbing, cytoplasmic condensation, and shrunken nucleus with more condensed chromatin. Moreover, APAN significantly increased protein expression of annexin V (apoptotic marker). Furthermore, APAN significantly increased protein expression of caspase 3 and P53. However, it significantly reduced secretion of VEGF protein into the medium and decreased protein expression of PCNA and Ki67 in HepG2 and HCT-116 cells. This study indicated that APAN had cytotoxic activity against HepG2 and HCT-116 cells via increasing the expression of apoptotic proteins and reducing the expression of proliferative proteins.

Synthesis and evaluation of novel xanthene-based thiazoles as potential antidiabetic agents.

A series of xanthene-based thiazoles was synthesized and characterized by different scpectroscopic methods, i.e. Proton nuclear magnetic resonance (1 H NMR), carbon nuclear magnetic resonance (13 C NMR), infrared spectroscopy, carbon hydrogen nitrogen analysis, and X-ray crystallography. The inhibition potencies of 18 newly synthesized thiazole derivatives were investigated on the activities of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-amylase (α-Amy), and α-glycosidase (α-Gly) enzymes in accordance with their antidiabetic and anticholinesterase ability. The synthesized compounds have the highest inhibition potential against the enzymes at low nanomolar concentrations. Among the 18 newly synthesized molecules, 3b and 3p were superior to the known commercial inhibitors of the enzymes and have a much more effective inhibitory potential, with IC50 : 2.37 and 1.07 nM for AChE, 0.98 and 0.59 nM for BChE, 56.47 and 61.34 nM for α-Gly, and 152.48 and 124.84 nM for α-Amy, respectively. Finally, the optimized 18 compounds were subjected to molecular docking to describe the interaction between thiazole derivatives and AChE, BChE, α-Amy, and α-Gly enzymes in which important interactions were monitored with amino acid residues of each target enzyme.

Synthesis, Biological Evaluation, and In Silico Studies of Novel Coumarin-Based 4H,5H-pyrano[3,2-c]chromenes as Potent ß-Glucuronidase and Carbonic Anhydrase Inhibitors.

The search for novel heterocyclic compounds with a natural product skeleton as potent enzyme inhibitors against clinical hits is our prime concern in this study. Here, a simple and facile two-step strategy has been designed to synthesize a series of novel coumarin-based dihydropyranochromenes (12a-12m) in a basic moiety. The synthesized compounds were thus characterized through spectroscopic techniques and screened for inhibition potency against the cytosolic hCA II isoform and ß-glucuronidase. Few of these compounds were potent inhibitors of hCA II and ß-glucuronidase with varying IC50 values ranging from 4.55 ± 0.22 to 21.77 ± 3.32 µM and 440.1 ± 1.17 to 971.3 ± 0.05 µM, respectively. Among the stream of synthesized compounds, 12e and 12i were the most potent inhibitors of ß-glucuronidase, while 12h, 12i, and 12j showed greater potency against hCA II. In silico docking studies illustrated the significance of substituted groups on the pyranochromene skeleton and binding pattern of these highly potent compounds inside enzyme pockets.

Addressing a Trapped High-Energy Water: Design and Synthesis of Highly Potent Pyrimidoindole-Based Glycogen Synthase Kinase-3ß Inhibitors.

In small molecule binding, water is not a passive bystander but rather takes an active role in the binding site, which may be decisive for the potency of the inhibitor. Here, by addressing a high-energy water, we improved the IC50 value of our co-crystallized glycogen synthase kinase-3ß (GSK-3ß) inhibitor by nearly two orders of magnitude. Surprisingly, our results demonstrate that this high-energy water was not displaced by our potent inhibitor (S)-3-(3-((7-ethynyl-9H-pyrimido[4,5-b]indol-4-yl)(methyl)amino)piperidin-1-yl)propanenitrile ((S)-15, IC50 value of 6 nM). Instead, only a subtle shift in the location of this water molecule resulted in a dramatic decrease in the energy of this high-energy hydration site, as shown by the WaterMap analysis combined with microsecond timescale molecular dynamics simulations. (S)-15 demonstrated both a favorable kinome selectivity profile and target engagement in a cellular environment and reduced GSK-3 autophosphorylation in neuronal SH-SY5Y cells. Overall, our findings highlight that even a slight adjustment in the location of a high-energy water can be decisive for ligand binding.

Discovery and Evaluation of Enantiopure 9H-pyrimido[4,5-b]indoles as Nanomolar GSK-3ß Inhibitors with Improved Metabolic Stability.

Glycogen synthase kinase-3ß (GSK-3ß) is a potential target in the field of Alzheimer's disease drug discovery. We recently reported a new class of 9H-pyrimido[4,5-b]indole-based GSK-3ß inhibitors, of which 3-(3-((7-chloro-9H-pyrimido[4,5-b]indol-4-yl)(methyl)amino)piperidin-1-yl)propanenitrile (1) demonstrated promising inhibitory potency. However, this compound underwent rapid degradation by human liver microsomes. Starting from 1, we prepared a series of amide-based derivatives and studied their structure-activity relationships against GSK-3ß supported by 1 µs molecular dynamics simulations. The biological potency of this series was substantially enhanced by identifying the eutomer configuration at the stereocenter. Moreover, the introduction of an amide bond proved to be an effective strategy to eliminate the metabolic hotspot. The most potent compounds, (R)-3-(3-((7-chloro-9H-pyrimido[4,5-b]indol-4-yl)(methyl)amino)piperidin-1-yl)-3-oxopropanenitrile ((R)-2) and (R)-1-(3-((7-bromo-9Hpyrimido[4,5-b]indol-4-yl)(methyl)amino)piperidin-1-yl)propan-1-one ((R)-28), exhibited IC50 values of 480 nM and 360 nM, respectively, and displayed improved metabolic stability. Their favorable biological profile is complemented by minimal cytotoxicity and neuroprotective properties.

Structural Optimization of a Pyridinylimidazole Scaffold: Shifting the Selectivity from p38α Mitogen-Activated Protein Kinase to c-Jun N-Terminal Kinase 3.

Starting from known p38α mitogen-activated protein kinase (MAPK) inhibitors, a series of inhibitors of the c-Jun N-terminal kinase (JNK) 3 was obtained. Altering the substitution pattern of the pyridinylimidazole scaffold proved to be effective in shifting the inhibitory activity from the original target p38α MAPK to the closely related JNK3. In particular, a significant improvement for JNK3 selectivity could be achieved by addressing the hydrophobic region I with a small methyl group. Furthermore, additional structural modifications permitted to explore structure-activity relationships. The most potent inhibitor 4-(4-methyl-2-(methylthio)-1H-imidazol-5-yl)-N-(4-morpholinophenyl)pyridin-2-amine showed an IC50 value for the JNK3 in the low triple digit nanomolar range and its binding mode was confirmed by X-ray crystallography.

Tri- and Tetrasubstituted Pyridinylimidazoles as Covalent Inhibitors of c-Jun N-Terminal Kinase 3.

The concept of covalent inhibition of c-Jun N-terminal kinase 3 (JNK3) was successfully transferred to our well validated pyridinylimidazole scaffold varying several structural features in order to deduce crucial structure-activity relationships. Joint targeting of the hydrophobic region I and methylation of imidazole-N1 position increased the activity and reduced the number of off-targets. The most promising covalent inhibitor, the tetrasubstituted imidazole 3-acrylamido-N-(4-((4-(4-(4-fluorophenyl)-1-methyl-2-(methylthio)-1H-imidazol-5-yl)pyridin-2-yl)amino)phenyl)benzamide (7) inhibits the JNK3 in the subnanomolar range (IC50 = 0.3 nM), shows high metabolic stability in human liver microsomes, and displays excellent selectivity in a screening against a panel of 410 kinases. Covalent bond formation to Cys-154 was confirmed by incubation of the inhibitors with wild-type JNK3 and JNK3-C154A mutant followed by mass spectrometry.

Fluorescence polarization-based assays for detecting compounds binding to inactive c-Jun N-terminal kinase 3 and p38α mitogen-activated protein kinase.

Two fluorescein-labeled pyridinylimidazoles were synthesized and evaluated as probes for the binding affinity determination of potential kinase inhibitors to the c-Jun N-terminal kinase 3 (JNK3) and p38α mitogen-activated protein kinase (MAPK). Fluorescence polarization (FP)-based competition binding assays were developed for both enzymes using 1-(3',6'-dihydroxy-3-oxo-3H-spiro[isobenzofuran-1,9'-xanthen]-5-yl)-3-(4-((4-(4-(4-fluorophenyl)-2-(methylthio)-1H-imidazol-5-yl)pyridin-2-yl)amino)phenyl)thiourea (5) as an FP probe (JNK3: Kd = 3.0 nM; p38α MAPK: Kd = 5.7 nM). The validation of the assays with known inhibitors of JNK3 and p38α MAPK revealed that both FP assays correlate very well with inhibition data received by the activity assays. This, in addition to the viability of both FP-based binding assays for the high-throughput screening procedure, makes the assays suitable as inexpensive prescreening protocols for JNK3 and p38α MAPK inhibitors.

An optimized and versatile synthesis to pyridinylimidazole-type p38α mitogen activated protein kinase inhibitors.

An optimized strategy for the synthesis of the potent p38α mitogen-activated protein kinase inhibitors 2-(2-hydroxyethylsulfanyl)-4-(4-fluorophenyl)-5-(2-aminopyridin-4-yl)imidazole (3) and 2-(2,3-dihydroxypropylsulfanyl)-4-(4-fluorophenyl)-5-(2-aminopyridin-4-yl)imidazole (4) starting from 2-fluoro-4-methylpyridine is reported. In contrast to a previously published synthesis starting from 2-bromo-4-methylpyridine, the overall yield could be increased from 3.6% to 29.4%. Moreover, this strategy avoids the use of palladium as a catalyst and is more diverse and versatile. Using this optimized protocol, both enantiomers of potent inhibitor 3 were synthesized. Biological data demonstrated that the (S)-enantiomer is the two times more potent eutomer.

Synthesis and in vitro testing of antimalarial activity of non-natural-type neocryptolepines: structure­activity relationship study of 2,11- and 9,11-disubstituted 6-methylindolo[2,3-b]quinolines.

This report describes the synthesis and in vitro anti-malarial evaluations of certain C2 or C8 and C11-disubstituted 6-methyl-5H-indolo[2,3-b]quinoline (neocryptolepine congener) derivatives. To attain higher activities, the structure­activity relationship (SAR) studies were conducted by varying the kind of alkylamino or ω-aminoalkylamino stubstituents at C11 and with Cl at the C2 position, or CO2Me at the C9 position. The anti-malarial activities of the tested compounds were significantly increased compared to the 11-non(alkylamino) derivatives. The 3-aminopropylamino group at C11 was further modified to urea and thiourea, which improved the cytotoxicity against normal cells. The best results were achieved with compounds 8 and 9d against the NF54 strain with the IC(50)/SI values as of 86 nM/20 and 317 nM/370, respectively. Furthermore, the compounds were tested for ß-haematin inhibition. Twelve were found to have IC(50) values below 100 µM and a linear correlation between the ß-haematin inhibition and cell growth inhibition in the NF54 strain was found for those derivatives with basic amino side chains. A second correlation was identified between the NF54 activity and physico-chemical factors related to solvation and polarity.