Synthesis, characterization, antiamoebic activity and cytotoxicity of new pyrazolo[3, 4-d]pyrimidine-6-one derivatives

A new series of pyrazolo[3,4-d]pyrimidine-6-one derivatives (2a-2j) were prepared by using the Biginelli multicomponent cyclocondensation of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (1a), different aromatic aldehydes, and urea with a catalytic amount of HCl at reflux temperature. These compounds were characterized by IR, (1)H NMR, (13)C NMR, and Mass spectral data. In vitro antiamoebic activity was performed against HM1:IMSS strain of Entamoeba histolytica. The results showed that the compounds 2b, 2i, and 2j with IC(50) values of 0.37 μM, 0.04 μM, and 0.06 μM, respectively, exhibited better antiamoebic activity than the standard drug metronidazole (IC(50)?=?1.33 μM). The toxicological studies of these compounds on human breast cancer MCF-7 cell line showed that the compounds 2b, 2i, and 2j exhibited >80% viability at the concentration range of 1.56-50 μM.     

The pharmacology of L-670,596, a potent and selective thromboxane/prostaglandin endoperoxide receptor antagonist

L-670,596 ((-)6,8-difluoro-9-rho-methylsulfonyl benzyl-1,2,3,4- tetrahydrocarbazol-1-yl-acetic acid) has been shown to be a potent receptor antagonist as evidenced by the inhibition of the binding of 125I-labeled PTA-OH to human platelets (IC50, 5.5 x 10(-9) M), inhibition of U-44069 induced aggregation of human platelet rich plasma (IC50, 1.1 x 10(-7) M), and competitive inhibition of contractions of the guinea pig tracheal chain induced by U-44069 (pA2,9.0). The compound was also active in vivo as shown by inhibition of arachidonic acid and U-44069 induced bronchoconstriction in the guinea pig (ED50 values, 0.04 and 0.03 mg/kg i.v., respectively), U44069 induced renal vasoconstriction in the pig (ED50, 0.02 mg/kg i.v.), and inhibition of ex vivo aggregation of rhesus monkey platelets to U-44069 (active 1-5 mg/kg p.o.). The selectivity of the compound was indicated by the failure to inhibit, first, ADP-induced human or primate platelet aggregation and, second, bronchoconstriction in the guinea pig in vivo and contraction of the guinea pig tracheal chain in vitro to a variety of agonists. It is concluded that L-670,596 is a potent, selective, orally active thromboxane A2/prostaglandin endoperoxide receptor antagonist.     

2-Benzamido-N-(1H-benzo[d]imidazol-2-yl)thiazole-4-carboxamide derivatives as potent inhibitors of CK1δ/ε

In this study we identified two heterocyclic compounds (5 and 6) as potent and specific inhibitors of CK1δ (IC(50)?=?0.040 and 0.042?μM, respectively). Whereas compound 5 exhibited fivefold higher affinity towards CK1δ than to CK1ε (IC(50) CK1ε?=?0.199?μM), compound 6 also inhibited CK1ε (IC(50)?=?0.0326?μM) in the same range as CK1δ. Selected compound 5 was screened over 442 kinases identifying 5 as a highly potent and selective inhibitor of CK1δ. X-ray analysis of 5 bound to CK1δ demonstrated its binding mode. In addition, characterization of 5 and 6 in a cell biological approach revealed the ability of both compounds to inhibit proliferation of tumor cell lines in a dose and cell line specific manner. In summary, our optimizations lead to the development of new highly selective CK1δ and ε specific inhibitors with biological activity.     

Synthesis and vasodilatory activity of new N-acylhydrazone derivatives, designed as LASSBio-294 analogues

Conventional therapy to treat hypertension often involves arterial vasodilation. Decrease of blood pressure by vasodilators is normally associated with adverse effects because of their low vascular selectivity. This is of interest to develop new molecules with potential for clinical use and fewer side effects. Recently, a new bioactive compound of the N-acylhydrazone class, LASSBio-294, was shown to produce a cardioinotropic effect and vasodilation. In this report, new derivatives of LASSBio-294 were designed and tested on the contractile response of vascular smooth muscle from Wistar rats. Phenylephrine-induced contracture in the aorta was inhibited by the derivatives LASSBio-785 and LASSBio-788. The concentrations necessary to cause 50% reduction of the maximal vascular response (IC50) were 10.2 +/- 0.5 and 67.9 +/- 6.5 microM. Vasodilation induced by both derivatives is likely to be mediated by a direct effect on smooth muscle because it was not dependent on the integrity of vascular endothelium. LASSBio-785 was seven times more potent than the reference compound LASSBio-294 (IC50 = 74 microM) in producing an endothelium-independent vasodilator effect.     

Novel bis(indolyl)hydrazide-hydrazones as potent cytotoxic agents

A series of bis(indolyl) hydrazide-hydrazones 5a-n were synthesized and evaluated for their cytotoxicity against selected human cancer cell lines. The reaction of indole-3-carboxaldehyde 2 with indole-3-carbohydrazide 4 in presence of catalytic amount of acetic acid afforded 5a-n in good yields. Among the synthesized bis(indolyl)hydrazide-hydrazones, the compound 5b with N-(p-chlorobenzyl) and bromo substituents was found to be the most potent against multiple cancer cell lines (IC(50)=1.0 μM, MDA-MB-231). The compound 5k exhibited selective cytotoxicity against breast cancer cell line MCF7 (IC(50)=3.1 μM).     

Design, synthesis and SAR study of hydroxychalcone inhibitors of human β-secretase (BACE1)

According to the structural characteristics of isoliquiritigenin from Glycyrrhiza uralensis, a series of hydroxychalcones has been designed, synthesized and evaluated for their in vitro inhibitory activities of β-secretase (BACE1). Structure-activity relationship study suggested that inhibitory activity against BACE1 was governed to a greater extent by the hydroxyl substituent on A- and B-ring of the chalcone, and the most active compound was substituted with four hydroxyl group (17, IC(50)?=?0.27 μM).     

Synthesis and acetylcholinesterase inhibitory activity of 2β,3α-disulfoxy-5α-cholestan-6-one

Disodium 2β,3α-dihydroxy-5α-cholestan-6-one disulfate (8) has been synthesized using cholesterol (1) as starting material. Sulfation was performed using trimethylamine-sulfur trioxide complex in dimethylformamide as the sulfating agent. The acetylcholinesterase inhibitory activity of compound 8 was evaluated and compared to that of disodium 2β,3α-dihydroxy-5α-cholestane disulfate (10) and diols 7 and 9. Compounds 8 and 10 were active with IC(50) values of 14.59 and 59.65 μM, respectively. Diols 7 and 9 showed no inhibitory activity (IC(50)>500 μM).     

Bioactive components from the heartwood of Pterocarpus santalinus

One new phenanthrenedione, pterolinus K (1), and one new chalcone, pterolinus L (2) were isolated from the heartwood extract of Pterocarpus santalinus. The structures were elucidated by spectroscopic methods. Both 1 and 2 showed inhibitory effect on elastase release by human neutrophils in response to fMLP with an IC(50) value of 4.24 and 0.95 μM, and compound 1 also inhibited superoxide anion generation with IC(50) value of 0.99 μM. In addition, compound 1 showed selective cytotoxicity against HepG2 with IC(50) value of 10.86 μM, while compound 2 showed a moderate cytotoxicity against KB with IC(50) values of 17.18 μM.     

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.     

Design, synthesis and antileishmanial in vitro activity of new series of chalcones-like compounds: a molecular hybridization approach

The chalcone-like series 1a-1g was efficiently synthesized from Morita-Baylis-Hillman reaction (52-74% yields). Compounds 1a-1g were designed by molecular hybridization based on the anti-inflammatory drug methyl salicylate (3) and the antileishmanial moiety of the Morita-Baylis-Hillman adducts 2a-2g. The 1a-1g compounds were much more actives than precursor series 2a-2g, for example, IC(50)=7.65 μM on Leishmania amazonensis and 10.14 μM on Leishmania chagasi (compound 1c) when compared to IC(50)=50.08 μM on L. amazonensis and 82.29 μM on L. chagasi (compound 2c). The IC(50) values of compound 3 (228.49 μM on L. amazonensis and 261.45 μM on L. chagasi) and acryloyl salicylate 4 (108.50 μM on L. amazonensis and 118.83 μM on L. chagasi) were determined here, by the first time, on Leishmania.     

Design and synthesis of novel inhibitors of human kynurenine aminotransferase-I

Herein we report 6-ethoxy-6-oxo-5-(2-phenylhydrazono) hexanoic acid and 3-(2-carboxyethyl)-1H-indole-2-carboxylic acid derivatives as synthetically accessible leads for human kynurenine aminotransferase-I (KAT-I) inhibitors. In total, 12 compounds were synthesized and their biological activities were determined using the HPLC-UV based KAT-I inhibition assay. Of the 12 compounds synthesized, 10 were found to inhibit human KAT-I and the most active compound was found to be 5-(2-(4-chlorophenyl) hydrazono)-6-ethoxy-6-oxohexanoic acid (9a) with an IC(50) of 19.8 μM.     

Synthesis and biological evaluation of novel N,N'-bis-methylenedioxybenzyl-alkylenediamines as bivalent anti-Alzheimer disease ligands

A novel series of N,N'-bis-methylenedioxybenzyl-alkylenediamines 5a-5g have been designed, synthesized and evaluated as bivalent anti-Alzheimer's disease ligands. The enzyme inhibition assay results indicated that compounds 5e-5g inhibit both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in the micromolar range (IC(50), 2.76-4.24 μM for AChE and 3.02-5.14 μM for BuChE), which was in the same potential as the reference compound rivastigmine (IC(50), 5.50 μM for AChE and 1.60 μM for BuChE). It was found that compounds could bind simultaneously to the peripheral and catalytic sites of AChE. β-Amyloid (Aβ) aggregation inhibition assay results showed that compound 5e exhibited highest self-mediated Aβ fibril aggregation inhibition activity (40.3%) with a similar potential as curcumin (41.6%). It was also found that 5e-5g did not affect neuroblastoma cell viability at the concentration of 50 μM.     

Synthesis of novel inhibitors of β-glucuronidase based on benzothiazole skeleton and study of their binding affinity by molecular docking

Benzothiazole derivatives 1-26 have been synthesized and their in vitro β-glucuronidase potential has been evaluated. Compounds 4 (IC(50)=8.9 ± 0.25 μM), 5 (IC(50)=36.1 ± 1.80 μM), 8 (IC(50)=8.9 ± 0.38 μM), 13 (IC(50)=19.4 ± 1.00 μM), 16 (IC(50)=4.23 ± 0.054 μM), and 18 (IC(50)=2.26 ± 0.06 μM) showed β-glucuronidase activity potent than the standard (d-saccharic acid 1,4-lactone, IC(50)=48.4 ± 1.25 μM). Compound 9 (IC(50)=94.0 ± 4.16 μM) is found to be the least active among the series. All active analogs were also evaluated for cytotoxicity and none of the compounds showed any cytotoxic effect. Furthermore, molecular docking studies were performed using the gold 3.0 program to investigate the binding mode of benzothiazole derivatives. This study identifies a novel class of β-glucuronidase inhibitors.     

Synthesis, biological evaluation, and molecular docking studies of 2,6-dinitro-4-(trifluoromethyl)phenoxysalicylaldoxime derivatives as novel antitubulin agents

A series of 2,6-dinitro-4-(trifluoromethyl)phenoxysalicylaldoxime derivatives (1h-20h) have been designed and synthesized, and their biological activities were also evaluated as potential antiproliferation and tubulin polymerization inhibitors. Among all the compounds, 2h showed the most potent activity in vitro, which inhibited the growth of MCF-7, Hep-G2 and A549 cell lines with IC(50) values of 0.70 ± 0.05, 0.68 ± 0.02 and 0.86 ± 0.05 μM, respectively. Compound 2h also exhibited significant tubulin polymerization inhibitory activity (IC(50)=3.06 ± 0.05 μM). The result of flow cytometry (FCM) demonstrated that compound 2h induced cell apoptosis. Docking simulation was performed to insert compound 2h into the crystal structure of tubulin at colchicine binding site to determine the probable binding model. Based on the preliminary results, compound 2h with potent inhibitory activity in tumor growth may be a potential anticancer agent.     

N -substituted 4-(4-carboxyphenoxy)benzamides. Synthesis and Evaluation as Inhibitors of Steroid-5α-reductase Type 1 and 2

In search of non-steroidal inhibitors of human prostatic 5 α -reductase, we recently described N -substituted 4′-biphenyl-4-carboxylic acids. Here, we report the optimisation of this series of compounds by increasing the conformational flexibility using an ether linker between the steroidal A-C ring mimetics. Ten new compounds were synthesised and tested against human and rat isozymes 1 and 2. The substances showed a broad range of activity from 36% inhibition at a concentration of 10 μM to an IC 50 value of 60 nM for compounds 22 and 29 respectively. The most potent compound 26 showed an IC 50 value improved by a factor of 5 from 1.9 μM to 0.38 μM in comparison with the parent biphenyl compound 15.     

Design, synthesis, and biological activity of thiazole derivatives as novel influenza neuraminidase inhibitors

A series of novel influenza neuraminidase (NA) inhibitors based on thiazole core were synthesized and evaluated for their ability to inhibit NA of influenza A virus (H(3)N(2)). All compounds were synthesized in good yields starting from commercially available 2-amino-4-thiazole-acetic ester using a suitable synthetic strategy. These compounds showed moderate inhibitory activity against influenza A NA. The most potent compound of this series is compound 4d (IC(50)?=?3.43 μM), which is about 20-fold less potent than oseltamivir, and could be used to design novel influenza NA inhibitors that exhibit increased activity based on thiazole ring.     

Trimethoxy-chalcone derivatives inhibit growth of Leishmania braziliensis: synthesis, biological evaluation, molecular modeling and structure-activity relationship (SAR)

In this work we described the synthesis, the antileishmanial activity and the molecular modeling and structure-activity relationship (SAR) evaluations of a series of chalcone derivatives. Among these compounds, the methoxychalcones 2h, 2i, 2j, 2k and 2l showed significant antileishmanial activity (IC(50)<10 μM). Interestingly 2i (IC(50)=2.7 μM), 2j (IC(50)=3.9 μM) and 2k (IC(50)=4.6 μM) derivatives presented better antileishmanial activity than the control drug pentamidine (IC(50)=6.0 μM). Our SAR study showed the importance of methoxy di-ortho substitution at phenyl ring A and the relationship between the frontier orbital HOMO coefficients distribution of these molecules and their activity. The most active compounds 2h, 2i, 2j, 2k, and 2l fulfilled the Lipinski rule-of-five which theoretically is important for good drug absorption and permeation through biological membranes. The potential profile of 2j (IC(50)=3.9 μM and CC(50)=216 μM) pointed this chalcone derivative as a hit compound to be further explored in antileishmanial drug design.     

Synthesis and biological screening of some pyridine derivatives as anti-malarial agents

Two series of pyridine derivatives were synthesised and evaluated for their in vivo anti-malarial activity against Plasmodium berghei. The anti-malarial activity was determined in vivo by applying 4-day standard suppressive test using chloroquine (CQ)-sensitive P. berghei ANKA strain-infected mice. Compounds 2a, 2g and 2h showed inhibition of the parasite multiplication by 90, 91 and 80%, respectively, at a dose level of 50 μmol/kg. Moreover, The most active compounds (2a, 2g and 2h) were tested in vitro against CQ-resistant Plasmodium falciparum RKL9 strains where compound 2g showed promising activity with IC(50)?=?0.0402 μM. The compounds were non-toxic at 300 and 100?mg/kg through the oral and parenteral routes, respectively. The docking pose of the most active compounds (2a, 2g and 2h) in the active site of dihydrofolate reductase enzyme revealed several hydrogen and hydrophobic interactions that contribute to the observed anti-malarial activities.     

Synthesis and biological evaluation of novel derivatives of gambogic acid as anti-hepatocellular carcinoma agents

A series of novel derivatives of gambogic acid (GA) were synthesized and evaluated for their in vitro cytotoxicity against human hepatocellular carcinoma (HCC) cells. All derivatives showed better aqueous solubility than GA, and compounds 3a, 3e, and 3f displayed potent inhibition of HCC cell proliferation (IC(50): 0.045-0.59 μM on Bel-7402 cells and 0.067-0.94 μM on HepG2 cells) superior to GA and taxol. Additionally, the most potent compound 3e did not affect significantly the proliferation of non-tumor liver cells, suggesting that it might selectively inhibit HCC proliferation. Furthermore, 3e induced high frequency of Bel-7402 cell apoptosis. Our findings suggest that these novel GA derivatives may hold a great promise as therapeutic agents for the intervention of human HCC.     

Synthesis and biological evaluation of isoxazolo[4,5-d]pyridazin-4-(5H)-one analogues as potent anti-inflammatory agents

In this study, eighteen new isoxazolo[4,5-d]pyridazin-4(5H)-one derivatives possessing either a 1,3,4-thiadiazole or a 1,2,4-triazole-5-thione moiety were synthesized and tested for anti-inflammatory activity in vitro (COX-1/COX-2, 5-LOX) and in vivo (rat paw edema assay). Compounds 15, 16, 25, 26 and 28-30 showed dual COX-2 (IC(50)'s in the 2.1-10.9 μM range), and 5-LOX (IC(50)'s in the 6.3-63.5 μM range) inhibitory activity. When administered orally to rats, dual COX-2/5-LOX inhibitors showed higher anti-inflammatory activity in vivo (30-45% reduction of the inflammatory response) than the reference drug ibuprofen (18%). Among dual COX-2/5-LOX inhibitors, the most potent compound (28) exhibited the best anti-inflammatory profile by inhibiting both COX-2 (IC(50)=2.1 μM) and 5-LOX (IC(50)=6.3 μM) enzymes. We investigated the binding interactions of compound 28 by an enzyme-ligand molecular modeling (docking) studies, which showed favorable binding interactions in both COX-2 and 5-LOX active sites. Furthermore, the dual acting COX-2/5-LOX compound 28 exhibited a superior gastrointestinal safety profile (ulcer index=0.25) compared to the reference drug ibuprofen (UI=7.0) when administered orally at the same molar dose. These observations suggest that isoxazolo[4,5-d]pyridazin-4(5H)-one analogs represent a new scaffold to design potent, effective, and safe anti-inflammatory agents possessing dual COX-2/5-LOX inhibitory activity.