Synthesis, structural elucidation, DNA-PK inhibition, homology modelling and anti-platelet activity of morpholino-substituted-1,3-naphth-oxazines

A number of new angular 2-morpholino-(substituted)-naphth-1,3-oxazines (compound 10b), linear 2-morpholino-(substituted)-naphth-1,3-oxazines (compounds 13b-c), linear 6, 7 and 9-O-substituted-2-morpholino-(substituted)-naphth-1,3-oxazines (compounds 17-22, 24, and 25) and angular compounds 14-16 and 23 were synthesised. The O-substituent was pyridin-2yl-methyl (15, 18, and 21) pyridin-3yl-methyl (16, 19, and 22) and 4-methylpipreazin-1-yl-ethoxy (23-25). Twelve compounds were tested for their inhibitory effect on collagen induced platelet aggregation and it was found that the most active compounds were compounds 19 and 22 with IC(50)=55±4 and 85±4 μM, respectively. Furthermore, the compounds were also assayed for their ability to inhibit DNA-dependent protein kinase (DNA-PK) activity. The most active compounds were 18 IC(50)=0.091 μM, 24 IC(50)=0.191 μM, and 22 IC(50)=0.331 μM. Homology modelling was used to build a 3D model of DNA-PK based on the X-ray structure of phosphatidylinositol 3-kinases (PI3Ks). Docking of synthesised compounds within the binding pocket and structure-activity relationships (SAR) analyses of the poses were performed and results agreed well with observed activity.     

Synthesis, in silico docking experiments of new 2-pyrrolidinone derivatives and study of their anti-inflammatory activity

A new class of 2-pyrrolidinone derivatives was designed, synthesized, and tested for their antioxidant and anti-inflammatory activities. The compounds were evaluated for their inhibitory activity against LOX. The most potent among them, 14d [IC(50) 0.08 (±0.005)mM], and 14e [IC(50) 0.0705 (±0.003)mM], were also tested in vivo. The compound 14d induced equipotent inhibition against rat paw edema, which is very close to the effect produced by the commonly used standard, namely indomethacin (47%). The LOX inhibitory activity of the compound 14e proceeds in parallel to the % inhibitory value of lipid peroxidation meaning that this LOX inhibitory activity is supported by the lipid peroxidation inhibition. The molecular features that govern their bioactivity were explored through in silico docking experiments. The results showed that acidic moieties must be placed in certain distance and orientation in the active site of LOX enzyme in order to productively exhibit inhibitory activity. In addition, the 2-pyrrolidinone template significantly contributes in the inhibitory properties of the new compounds.     

Design, synthesis and vasorelaxant evaluation of novel coumarin-pyrimidine hybrids

The main objective of the present work depends on the hybridization of coumarin moiety as a vasorelaxant scaffold and pyrimidine ring with known potential cardiovascular activity in order to prepare some new potent antihypertensive candidates. Hence, two groups of pyrimidinyl coumarin derivatives were synthesized and evaluated for their vasorelaxing activity. These compounds were prepared via two routes; either preparation of the guanidinocoumarin 4 followed by a cocktail of cyclization reactions to yield a different array of 6-(substituted pyrimidin-2-yl)aminocoumarins 5-17, or through cyclization of the precursor chalcones 22a-g with guanidine hydrochloride to generate the corresponding final compounds, 8-(6-aryl-2-aminopyrimidin-4-yl)-7-methoxycoumarins 23a-g. The effect of these compounds and the coumarin intermediates 3, 4, 21 and 22a-g on nor-epinephrine induced contracture in thoracic rat aortic rings was investigated using prazocin as reference drug. Several derivatives showed promising activities either equal or even better than that of prazocin (IC(50) 0.487 mM). The most prospective compounds; the pyrimidinylamino coumarin derivatives 8, 17 (IC(50) 0.411, IC(50) 0.421 mM) and the chalcones 22b, 22e (IC(50) 0.371, 0.374 mM) that displayed the highest activity can be a base for lead optimization and simple but efficient design of new compounds. 2D-QSAR analysis was applied to find a correlation between the experimental vasorelaxant activities of the newly synthesized coumarin derivatives and their different physicochemical parameters. The result of this study showed that the increase in aqueous solubility while retaining good hydrophobic character of the overall molecule is the key for maintaining high relaxation activity.     

Design,synthesis, docking,ADMET studies,and anticancer evaluation of new 3-methylquinoxaline derivatives as VEGFR-2 inhibitors and apoptosis inducers

Vascular endothelial growth factor receptor-2 (VEGFR-2) plays a critical role in cancer angiogenesis. Inhibition of VEGFR-2 activity proved effective suppression of tumour propagation. Accordingly, two series of new 3-methylquinoxaline derivatives have been designed and synthesised as VEGFR-2 inhibitors. The synthesised derivatives were evaluated in vitro for their cytotoxic activities against MCF-7and HepG2 cell lines. In addition, the VEGFR-2 inhibitory activities of the target compounds were estimated to indicate the potential mechanism of their cytotoxicity. To a great extent, the results of VEGFR-2 inhibition were highly correlated with that of cytotoxicity. Compound 27a was the most potent VEGFR-2 inhibitor with IC₅₀ of 3.2 nM very close to positive control sorafenib (IC₅₀ = 3.12 nM). Such compound exhibited a strong cytotoxic effect against MCF-7 and HepG2, respectively with IC₅₀ of 7.7 and 4.5 µM in comparison to sorafenib (IC₅₀ = 3.51 and 2.17 µM). In addition, compounds 28, 30f, 30i, and 31b exhibited excellent VEGFR-2 inhibition activities (IC₅₀ range from 4.2 to 6.1 nM) with promising cytotoxic activity. Cell cycle progression and apoptosis induction were investigated for the most active member 27a. Also, the effect of 27a on the level of caspase-3, caspase-9, and BAX/Bcl-2 ratio was determined. Molecular docking studies were implemented to interpret the binding mode of the target compounds with the VEGFR-2 pocket. Furthermore, toxicity and ADMET calculations were performed for the synthesised compounds to study their pharmacokinetic profiles     

Synthesis, cytotoxicity, and DNA topoisomerase II inhibitory activity of benzofuroquinolinediones

Benzofuroquinolinediones (7c and 7d) were synthesized by base-catalyzed condensation of dichloroquinolinediones with phenolic derivatives. Their dialkylaminoalkoxy derivatives (8i-8p) were prepared by reaction with various dialkylaminoalkyl chlorides. The cytotoxicity of the synthesized compounds was evaluated against eight types of human cancer cell lines, and their topoisomerase II inhibition was assessed. In general, the cytotoxicity of benzofuroquinolinediones (8i-8p) was similar or superior to that of doxorubicin and showed more potent inhibitory activity than naphthofurandiones (8a-8h). Also, most of the compounds exhibited excellent topoisomerase II inhibitory activity at a concentration of 5 microM and two compounds, 8d and 8i, showed IC50 values of 1.19 and 0.68 microM, respectively, and were much more potent than etoposide (IC50=78.4 microM), but similar to doxorubicin (IC50=2.67 microM). However their inhibitory activity on topoisomerase I was lower, and 8d and 8i showed IC50 values of 42.0 and 64.3 microM, respectively.     

The novel C-5 aryl, alkenyl, and alkynyl substituted uracil derivatives of L-ascorbic acid: synthesis, cytostatic, and antiviral activity evaluations

The novel C-5 substituted uracil derivatives of l-ascorbic acid were synthesized by coupling of 5-iodouracil-4,5-didehydro-5,6-dideoxy-l-ascorbic acid with unsaturated stannanes under Stille reaction conditions. The new compounds were evaluated for their antitumoral and antiviral activities. Among all compounds evaluated the 5-propynyl substituted uracil derivative of l-ascorbic acid (7) exhibited the most pronounced cytostatic activities against all examined tumor cell lines (IC(50): 0.2-0.78 microM). However, this compound was also cytotoxic to human normal fibroblasts WI 38. The 5-(phenylethynyl)uracil-2,3-di-O-benzylated l-ascorbic acid derivative (4) exhibited an albeit slight (IC(50): 55-108 microM), but selective inhibitory effect toward all tumor cell lines except for cervical carcinoma (HeLa), pancreatic carcinoma (MiaPaCa-2), laryngeal carcinoma (Hep-2), and colon carcinoma (SW 620), and no cytotoxicity to normal human fibroblast (WI 38). Compound 7 showed some, not highly specific, inhibitory potential against vesicular stomatitis virus, Coxsackie B4 virus, and Sindbis viruses (EC(50): 1.6 microM).     

Changes induced by caffeine, theophylline and theobromine on calcium uptake, respiration and ATP levels in rat-liver mitochondria

1. The inhibition of calcium uptake and cellular respiration depend on the concentration of the compounds as shown by the concentration-effect curves. 2. The concentrations at which 50% inhibition of the transport of calcium takes place (caffeine 45 mM, theophylline 12 mM, theobromine, 4 mM) do not coincide exactly with those that produce the same effect on cellular respiration (caffeine 60 mM, theophylline 22 mM, theobromine 8 mM). 3. ATP concentrations under different conditions were also determined; a decrease in their value induced by the drugs was observed. No significant differences were observed, however, between the effect produced by the methyl-xanthines. 4. These findings suggest that these compounds are able to affect in some way the maintenance of energy gradients linked to the effects studied.     

Design, synthesis, and biological evaluation of chalcone oxime derivatives as potential immunosuppressive agents

A series of deoxybenzoin oximes were recently reported as potent immunosuppressive agents by our group. In order to continue the original research for potential immunosuppressive agents with high efficacy and low toxicity, we synthesized a series of new chalcone oximes and evaluated them for their cytotoxicities and immunosuppressive activities. Among the synthesized compounds, chalcone oximes 25 and 27 exhibited lower cytotoxicities and higher inhibitory activities on anti-CD3/anti-CD28 co-stimulated lymph node cells than other compounds. Specially, compound 27 displayed 200-fold lower cytotoxicity (CC(50)=2174.39 μM) than cyclosporin A (CC(50)=10.10 μM) and showed SI value (SI=176.69) close to cyclosporin A (SI=154.13). Besides, the preliminary mechanism of inhibition effect of compounds 25 and 27 was also detected by flow cytometry, and the compounds exerted immunosuppressive activities via inducing the apoptosis of activated lymph node cells in a dose dependent manner. Also, the deep mechanism of apoptosis was detected by Western blot analysis.     

Secondary metabolites of ponderosa lemon (Citrus pyriformis) and their antioxidant, anti-inflammatory, and cytotoxic activities

Column chromatography of the dichloromethane fraction from an aqueous methanolic extract of fruit peel of Citrus pyriformis Hassk. (Rutaceae) resulted in the isolation of seven compounds including one coumarin (citropten), two limonoids (limonin and deacetylnomilin), and four sterols (stigmasterol, ergosterol, sitosteryl-3-beta-D-glucoside, and sitosteryl-6'-O-acyl-3-beta-D-glucoside). From the ethyl acetate fraction naringin, hesperidin, and neohesperidin were isolated. The dichloromethane extract of the defatted seeds contained three additional compounds, nomilin, ichangin, and cholesterol. The isolated compounds were identified by MS (EI, CI, and ESI), 1H, 13C, and 2D-NMR spectral data. The limonoids were determined qualitatively by LC-ESI/MS resulting in the identification of 11 limonoid aglycones. The total methanolic extract of the peel and the petroleum ether, dichloromethane, and ethyl acetate fractions were screened for their antioxidant and anti-inflammatory activities. The ethyl acetate fraction exhibited a significant scavenging activity for DPPH free radicals (IC50 = 132.3 microg/mL). The petroleum ether fraction inhibited 5-lipoxygenase with IC50 = 30.6 microg/mL indicating potential anti-inflammatory properties. Limonin has a potent cytotoxic effect against COS7 cells [IC50 = (35.0 +/- 6.1) microM] compared with acteoside as a positive control [IC50 = (144.5 +/- 10.96) microM].     

Synthesis,docking studies,in vitro cytotoxicity evaluation and DNA damage mechanism of new tyrosine-based tripeptides

Peptides are one of the leading groups of compounds that have been the subject of a great deal of biological research and still continue to attract researchers' attention. In this study, a series of tripeptides based on tyrosine amino acids were synthesized by the triazine method. The cytotoxicity properties of all compounds against human cancer cell lines (MCF-7), ovarian (A2780), prostate (PC-3), and colon cancer cell lines (Caco-2) were determined by the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay method, and % cell viability and logIC50 values of the compounds were calculated. Significant decreases in cell viability were observed in all cells (p < 0.05). The comet assay method was used to understand that the compounds that showed a significant decrease in cell viability had this effect through DNA damage. Most of the compounds exhibited cytotoxicity by DNA damage mechanism. Besides, their interactions between investigated molecule groups with PDB ID: 3VHE, 3C0R, 2ZCL, and 2HQ6 target proteins corresponding to cancer cell lines, respectively, were investigated by docking studies. Finally, molecules with high biological activity against biological receptors were determined by ADME analysis.     

Indole derivatives as potent inhibitors of 5-lipoxygenase: design, synthesis, biological evaluation, and molecular modeling

A series of novel indole derivatives was designed, synthesized and evaluated by cell-based assays for their inhibitory activities against 5-LOX in rat peritoneal leukocytes. Most of them (30 out of 35) showed an inhibitory potency higher than the initial screening hit 1a (IC(50)=74 microM). Selected compounds for concentration-response studies showed prominent inhibitory activities with IC(50) values ranging from 0.74 microM to 3.17 microM. Four compounds (1m, 1s, 4a, and 6a) exhibited the most potent inhibitory activity compared to that of the reference drug (Zileuton), with IC(50) values less than 1 microM. Molecular modeling studies for compounds 1a, 3a, 4a, and 6a were also presented. The excellent in vitro activities of this class of compounds may possess potential for the treatment of LT-related diseases.     

Antihistamine, anticholinergic and cardiovascular effects of 2-substituted-4-phenylquinoline derivatives

Eleven new derivatives of 4-phenylquinoline, having various substituents at the 2-position of the quinoline ring, were previously synthesized. The antidepressant activities of these derivatives were demonstrated by their antagonism to reserpine-induced hypothermia in mice. The ED50 values were found to be in the range of 12-42 mg/kg (imipramine is 21.0 mg/kg). In the present work, comparative studies of the effects of these new drugs on the cholinergic and histaminergic (H1) systems, as well as their effects on the cardiovascular system, are presented. Both imipramine and trazodone were utilized as standards representing typical and atypical antidepressant drugs, respectively. All these new compounds have very low antihistaminic (H1) activities, as compared to imipramine. In addition, a clear cut separation of the antidepressant activity from the antihistaminic (H1) activity was observed. These compounds have weak anticholinergic (atropine-like properties) activity as compared to imipramine, using the isolated guinea-pig ileum. Animal studies of the cardiac toxicity of these compounds showed reduced lethality for some of them as compared to imipramine. Arrhythmias commonly associated with imipramine were absent for most of these compounds. The effects of these compounds on the heart conduction were determined by electrocardiographic studies. Although some of these compounds do not interfere with heart conduction, as compared to imipramine most were inferior to trazodone. Correlation between the pharmacological activities and structural modifications of these derivatives has also been observed.     

Urease inhibitory activity of simple alpha,beta-unsaturated ketones

A variety of alpha,beta-unsaturated ketones were evaluated for their effect on the jack bean urease. Of 35 compounds tested, 2-cyclohepten-1-one (1), 2-cyclohexen-1-one (2), 2-cyclopenten-1-one (3), and 5,6-dihydro-2H-pyran-2-one (4) showed potent inhibitory activities against the enzyme. The most potent compound (1) (IC50=0.16 mM) showed similar inhibitory potency to hydroxyurea (IC50=0.095 mM). The inhibitory effects of 1, 2, 3, and 4 were significantly reduced by 2-mercaptoethanol or dithiothreitol. These data suggest that alpha,beta-unsaturated ketones inhibited the urease activity, possibly by a Michael-like addition of a protein SH group to the double bond of the alpha,beta-unsaturated carbonyl group.     

Synthesis, dihydrofolate reductase inhibition, antitumor testing, and molecular modeling study of some new 4(3H)-quinazolinone analogs

In order to produce potent new leads for anticancer drugs, a new series of quinazoline analogs was designed to resemble methotrexate (MTX, 1) structure features and fitted with functional groups believed to enhance inhibition of mammalian DHFR activity. Molecular modeling studies were used to assess the fit of these compounds within the active site of human DHFR. The synthesized compounds were evaluated for their ability to inhibit mammalian DHFR in vitro and for their antitumor activity in a standard in vitro tissue culture assay panel. Compounds 28, 30, and 31 were the most active DHFR inhibitors with IC₅₀ values of 0.5, 0.4, and 0.4 μM, respectively. The most active antitumor agents in this study were compounds 19, 31, 41, and 47 with median growth inhibitory concentrations (GI₅₀) of 20.1, 23.5, 26.7, and 9.1 μM, respectively. Of this series of compounds, only compound 31 combined antitumor potency with potent DHFR inhibition; the other active antitumor compounds (19, 41, and 47) all had DHFR IC₅₀ values above 15 μM, suggesting that they might exert their antitumor potency through some other mode of action. Alternatively, the compounds could differ significantly in uptake or concentration within mammalian cells.     

Design,synthesis and evaluation of some new 4-aminopyridine derivatives in learning and memory

Some new anilide and imide derivatives of 4-aminopyridine (4AP) were synthesized and evaluated against antiamnesic, cognition enhancing and anticholinesterase activity through their respective in vitro and in vivo models. These newly synthesized derivatives have illustrated an enhanced cognition effect on elevated plus maze model and also demonstrated a significant reversal in scopolamine-induced amnesia in same model. The IC₅₀ value of synthesized compounds showed maximum activity of 4APMb compared to standard drug donepezil and other derivatives, whereas its enzyme kinetic study revealed a non-competitive inhibition of acetycholinesterase (AChE) and a competetive inhibition of butyrylcholinesterase (BChE). Significant inhibitions in AChE activity by all the synthesized compounds were found in specific brain regions that is prefrontal cortex, hippocampus and hypothalamus. The docking study confirmed their consensual interaction with AChE, showed an affinity and binding with the key peripheral anionic site residues Trp-286, Tyr-124 and Tyr-341 of AChE.     

E,E-2-Benzylidene-6-(nitrobenzylidene)cyclohexanones: syntheses, cytotoxicity and an examination of some of their electronic, steric, and hydrophobic properties

Three series of structurally isomeric 2-benzylidene-6-(nitrobenzylidene) cyclohexanones 1-3 were prepared and evaluated against human Molt/C8 and CEM T-lymphocytes as well as murine L1210 cells. The IC(50) values of the majority of compounds are less than 10microM and in some assays, the figures for 1d and 1e are submicromolar. Correlations were discerned between cytotoxic potencies and the atomic charges on one of the olefinic carbon atoms, the torsion angles between an aryl ring, and the adjacent unsaturated group as well as logP values. Three representative compounds were examined for their effect on respiration in rat liver mitochondria.     

Identification and evaluation of apoptotic compounds from Garcinia oligantha

Four new compounds, oliganthins A-D (1-4), and one known caged xanthone gaudichaudione H (5) were isolated from the stems of Garcinia oligantha. The structures of the new compounds were elucidated by spectroscopic evidences. All of the five compounds were evaluated for their apoptosis-inducing effects using HeLa-C3 cells which have been genetically engineered to produce a fluorescent biosensor capable of detecting caspase-3 activation. All of them induced cell apoptosis at 10 μM or lower concentrations. The apoptotic activity of oliganthins A, B and gaudichaudione H were further confirmed by detecting the cleavage of PARP, which is the substrate of activated caspase-3, in these compounds-treated cells using the method of Western blot. Moreover, the values of IC(50) were measured for all five compounds on HeLa cells using the MTT assay. Among them, gaudichaudione H had the lowest IC(50) value of 0.90 μM, while the other four new compounds had IC(50) values of 1.58, 1.52, 4.15, and 7.82 μM, respectively. These results show that gaudichaudione H has the strongest apoptosis-inducing effect and cell growth inhibition effect among these xanthones and it may have the potential to be developed into a new anticancer agent.     

In vitro antiplasmodial activities of semisynthetic N,N'-spacer-linked oligomeric ergolines

Starting from three monomeric ergolines (terguride 1, festuclavine 2, pergolide 3) N,N'-spacer-linked oligomeric derivatives were prepared using different aliphatic or arylalkyl spacers. The compounds have been evaluated for their in vitro antiplasmodial activity against the chloroquine-sensitive strain poW and the chloroquine-resistant clone Dd2 of Plasmodium falciparum. Additionally, the cytotoxic effects against mouse fibroblasts (NIH 3T3) in vitro, and human hepatocytes were evaluated. All monomers displayed only a weak antiplasmodial effect, but N-1,N-1'-spacer-linked dimerization substantially enhanced their antiplasmodial activity. The best activities were observed for compounds showing a distance of six carbon atoms between two monomers, which can be obtained by aliphatic or p-xylene linkers. The N-6,N-6'-spacer-linked depropylpergolide dimer 3i exhibited the highest antiplasmodial activity of all compounds tested (IC(50) values: 0.14 and 0.13 microM against poW and Dd2, respectively). Unfortunately, it displayed toxic effects against the mouse fibroblast cell line NIH 3T3 (IC(50): 0.1+/-0.09 microM) and also against human hepatocytes at 100 microM (LDH-leakage: 15.58+/-0.87 microkat/L; GSH-level: 8.15+/-0.78 nmol/10(6) cells). However, the N-1,N-1'-spacer-linked trimer of festuclavine (2f), and also the N-1,N-1'-spacer-linked tetramer of terguride (1g) possessed remarkable antiplasmodial activities (IC(50): 0.54 and 1.53 microM, respectively, against Dd2) lacking cytotoxicity.     

Structure-based design,synthesis, and evaluation of structurally rigid donepezil analogues as dual AChE and BACE-1 inhibitors

A new series of structurally rigid donepezil analogues was designed, synthesized and evaluated as potential multi-target-directed ligands (MTDLs) against neurodegenerative diseases. The investigated compounds 10–13 displayed dual AChE and BACE-1 inhibitory activities in comparison to donepezil, the FDA-approved drug. The hybrid compound 13 bearing 2-aminoquinoline scaffold exhibited potent AChE inhibition (IC₅₀ value of 14.7?nM) and BACE-1 inhibition (IC₅₀ value of 13.1?nM). Molecular modeling studies were employed to reveal potential dual binding mode of 13 to AChE and BACE-1. The effect of the investigated compounds on the viability of SH-SY5Y neuroblastoma cells and their ability to cross the blood-brain barrier (BBB) in PAMPA-BBB assay were further studied.