Derivatives of oxoisoaporphine alkaloids: a novel class of selective acetylcholinesterase inhibitors

A series of 9-aminoalkanamido-1-azabenzanthrones derviatives (3a-i Ar-NHCO(CH(2))(n)NR(1)R(2)) and their quaternary methiodide salts (4a-g Ar-NHCO(CH(2))(n)N(+)(CH(3))R(1)R(2)I(-)) were designed and synthesized as acetylcholinesterase (AChE) or butyrylcholinesterase (BuChE) inhibitors. The synthetic compounds exhibited high AChE inhibitory activity with IC(50) values in the nanomolar range and high selectivity for AChE over BuChE (45- to 1980-fold). The structure-activity relationships (SARs) were discussed.     

Lipase-catalysed synthesis of new acetylcholinesterase inhibitors: N-benzylpiperidine aminoacid derivatives

New acetylcholinesterase inhibitors were synthetized via a lipase-mediated regioselective amidation using Candida antarctica lipase B as a biocatalyst in the key step. The new compounds have two different structural fragments: a N-benzylpiperidine moiety to anchor the enzyme active site and a dicarboxylic aminoacid to act as a biological carrier. Some analogues of N-benzylpiperazine were also synthesised and studied but they did not display AChE inhibitor activity. A preliminary structure activity relationship study was performed employing some computational techniques as similarity indices and electrostatic potential maps.     

Discovery of 2-phenyl-3-sulfonylphenyl-indole derivatives as a new class of selective COX-2 inhibitors

2-Sulfonylphenyl-3-phenyl-indole derivatives have been reported to be highly potent and selective COX-2 inhibitors previously. In this paper, the regio-isomeric analogues-2-phenyl-3-sulfonylphenyl-indoles were identified as potent and selective COX-2 inhibitors. This work led to the discovery of compounds 4a and 8a possessing higher activity than Celecoxib on cellular assay.     

2,3-Diarylbenzopyran derivatives as a novel class of selective cyclooxygenase-2 inhibitors

A new series of cyclooxygenase-2(COX-2) inhibitors with naturally occurring flavone as the main skeleton has been synthesized and their biological activities were evaluated for cyclooxygenase inhibitory activity. Rational structural modifications were applied to potent COX-2 inhibitors to obtain the desired pharmacokinetic profiles for improved oral anti-inflammatory activity.     

Isocoumarins: a new class of selective carbonic anhydrase IX and XII inhibitors

Isocoumarins, isomeric to comarins which act as effective carbonic anhydrase (CA, EC 4.2.1.1) inhibitors, were investigated for the first time as inhibitors of this enzyme. A series of 3-substituted and 3,4-disubstituted isocoumarins incorporating phenylhydrazone, 1-phenyl-pyrazole and pyrazolo-substituted pyrimidine trione/thioxo-pyrimidine dione moieties were investigated for their interaction with four human (h) CA isoforms, hCA I, II, IX and XII, known to be important drug targets. hCA I and II were not inhibited by these compounds, whereas hCA IX and XII were inhibited in the low micromolar range by the less bulky derivatives. The inhibition constants ranged between 2.7–78.9 µM against hCA IX and of 1.2–66.5 µM against hCA XII. As for the coumarins, we hypothesise that the isocoumarins are hydrolysed by the esterase activity of the enzyme with formation of 2-carboxy-phenylacetic aldehydes which act as CA inhibitors. Isocoumarins represent a new class of CA inhibitors.     

Naphthalene derivatives: A new series of selective cyclooxygenase-2 inhibitors

A new series of potent and selective cyclooxygenase-2 inhibitors have been prepared. Some of these compounds show good oral anti-inflammatory activity in rats.     

5-Substituted-2,3-diphenyltetrahydrofurans: a new class of moderately selective COX-2 inhibitors

The nature of C-5 substituent and the configuration at C-5 carbon of 2,3-diphenyltetrahydrofurans, with chiral centres at C-2, C-3 and C-5, show a remarkable influence on their COX-2 inhibition and selectivity. Out of the eight compounds investigated here, 1b with COOH group and R* configuration at C-5, and 2d with CH2SCH2CH3 group and S* configuration at C-5 have been identified as lead molecules for further studies on COX-2 inhibition.     

Pyrimidine-2,4,6-Triones: a new effective and selective class of matrix metalloproteinase inhibitors

Matrix metalloproteinases (MMPs) are a family of zinc endopeptidases that have been implicated in various disease processes. Different classes of MMP inhibitors, including hydroxamic acids, phosphinic acids and thiols, have been previously described. Most of these mimic peptides and most likely bind in a similar way to the corresponding peptide substrates. Here we describe pyrimidine-triones as a completely new class of metalloprotease inhibitors. While the pyrimidine-trione template is used as the zinc-chelating moiety, the substituents have been optimized to yield inhibitors comparable in their inhibition efficiency of matrix metalloproteinases to hydroxamic acid derivatives such as batimastat. However, they are much more specific for a small subgroup of MMPs, namely the gelatinases (MMP-2 and MMP-9).     

Isoquinoline derivatives as potential acetylcholinesterase inhibitors

Several bisbenzylisoquinoline alkaloid derivatives showed the inhibitory activity at acetylcholinesterase enzyme (AChE) in micromolar range. It is possible that monomeric moiety of bisbenzylisoquinoline alkaloid might be required for acetylcholinesterase enzyme inhibition. AChE inhibitory activity of related monomeric 1-benzylisoquinolines was examined by using Ellman colorimetric assay with galanthamine as a reference standard.     

Methyl 2-(2-(4-formylphenoxy)acetamido)-2-substituted acetate derivatives: a new class of acetylcholinesterase inhibitors

A new class of inhibitors of acetylcholinesterase (methyl 2-(2-(4-formylphenoxy)acetamido)-2-substituted acetate derivatives) is described. Compounds 4b and 4i were found to be more potent than galanthamine in inhibiting acetylcholinesterase.     

Fullerene derivatives as a new class of inhibitors of protein tyrosine phosphatases

In this study, we identified water-soluble C₆₀ and C₇₀ fullerene derivatives as a novel class of protein tyrosine phosphatase inhibitors. The evaluated compounds were found to inhibit CD45, PTP1B, TC-PTP, SHP2, and PTPβ with IC₅₀ values in the low micromolar to high nanomolar range. These results demonstrate a new strategy for designing effective nanoscale protein tyrosine phosphatase inhibitors.     

Amino acid anthranilamide derivatives as a new class of glycogen phosphorylase inhibitors

A series of amino acid anthranilamide derivatives identified from a high-throughput screening campaign as novel, potent, and glucose-sensitive inhibitors of human liver glycogen phosphorylase a are described. A solid-phase synthesis using Wang resin was also developed which provided efficient access to a variety of analogues, and resulted in the identification of key structure–activity relationships, and the discovery of a potent exemplar (IC₅₀ = 80 nM). The SAR scope, synthetic strategy, and in vitro results for this series are presented herein.     

Serotonin derivatives as a new class of non-ATP-competitive receptor tyrosine kinase inhibitors

The discovery of new templates and their subsequent elaboration to clinically useful receptor tyrosine kinase (RTK) inhibitors continues to be an important issue. RTKs are a class of enzymes responsible for the activation of different cellular signal transduction cascades. The majority of the known small molecules RTK inhibitors are ATP-competitive and they are multiple targeted inhibitors. We describe here serotonin derivatives as a new class of multiple targeted RTK inhibitors. In contrast to most other RTK inhibitors they act via a non-ATP-competitive (allosteric) mechanism. Furthermore, they are able to inhibit the proliferation of HUVE cells, fibroblasts and two cancer cell lines.     

1-(1-Arylethylidene)thiosemicarbazide derivatives: a new class of tyrosinase inhibitors

A series of 1-(1-arylethylidene)thiosemicarbazide compounds and their analogues were synthesized and characterized by 1H NMR, MS. Their tyrosinase inhibitory activities were investigated by an assay based on the catalyzing ability of tyrosinase for the oxidation of L-DOPA, comparing with 4-methoxycinnamic acid and arbutin. The results showed that (1) all the synthesized compounds could perform a significant inhibitory activity for tyrosinase; (2) for these compounds, the main active moiety interacting with the center of tyrosinase would be thiosemicarbazo group; (3) the inhibitory activity was close related with thiosemicarbazide moieties and the groups attached on the aromatic ring.     

Discovery of 2-arylquinazoline derivatives as a new class of ASK1 inhibitors

The development of a new series of apoptosis signal-regulating kinase 1 (ASK1) inhibitors is described. Starting from purine, pyrimidine and quinazoline scaffolds identified by high throughput screening, we used tools of structure-based drug design to develop a series of potent kinase inhibitors, including 2-arylquinazoline derivatives 12 and 23, with submicromolar inhibitory activities against ASK1. Kinetic analysis demonstrated that the 2-arylquinazoline scaffold ASK1 inhibitors described herein are ATP competitive.     

Tetraketones: a new class of tyrosinase inhibitors

Twenty-eight tetraketones (1-28) with variable substituents at C-7 were synthesized and evaluated as tyrosinase inhibitors. Remarkably compounds 25 (IC(50)=2.06 microM), 11 (IC(50)=2.09 microM), 15 (IC(50)=2.61 microM), and 27 (IC(50)=3.19 microM) were found to be the most active compounds of the series, even better than both standards kojic acid (IC(50)=16.67 microM) and L-mimosine (IC(50)=3.68 microM). This study may lead to the discovery of therapeutically potent agents against clinically very important dermatological disorders including hyperpigmentation as well as skin melanoma.     

Synthesis of aminoalkyl-substituted coumarin derivatives as acetylcholinesterase inhibitors

Alzheimer’s disease, one of the most common forms of dementia, is a progressive neurodegenerative disorder symptomatically characterized by declines in memory and cognitive abilities. To date, the successful therapeutic strategy to treat AD is maintaining levels of acetylcholine by inhibiting acetylcholinesterase (AChE). In the present study, coumarin derivatives were designed and synthesized as AChE inhibitors based on the lead structure of scopoletin. Of those synthesized, pyrrolidine-substituted coumarins 3b and 3f showed ca. 160-fold higher AChE inhibitory activities than scopoletin. These compounds also ameliorated scopolamine-induced memory deficit in mice when administered orally at the dose of 1 and 2 mg/kg.     

Novel dehydroabietylamine derivatives as potent inhibitors of acetylcholinesterase

Nowadays, the inhibition of acetylcholinesterase is one of the main pharmacological strategies for the treatment of Alzheimer’s disease. Therefore, a set of thirty-four derivatives of the diterpenoid dehydroabietylamine has been synthesized and screened in colorimetric Ellman’s assays to determine their ability to inhibit the enzymes acetylcholinesterase (AChE, from electric eel) and butyrylcholinesterase (BChE, from equine serum). A systematic variation of the substitution of dehydroabietylamides enabled an approach to analogs showing a remarkable inhibition potency for AChE. Particularly N-benzoyldehydroabietylamines 11, 12 and 13 were excellent inhibitors for AChE, showing inhibition rates comparable to standard galantamine hydrobromide.     

Bisaryldiketene derivatives: A new class of selective ligands for c-myc G-quadruplex DNA

A series of bisaryldiketene derivatives were designed and synthesized as a new class of specific G-quadruplex ligands. The ligand-quadruplex interactions were further evaluated by FRET, ITC, and PCR stop assay. In contrast to most of the G-quadruplex ligands reported so far, which comprise an extended aromatic ring, these compounds are neither polycyclic nor macrocyclic, but have a non-aromatic and relative flexible linker between two quinoline moieties enabling the conformation of compounds to be flexible. Our results showed that these bisaryldiketene derivatives could selectively recognize G-quadruplex DNA rather than binding to duplex DNA. Moreover, they showed promising discrimination between different G-quadruplex DNA. The primary binding affinity of ligand M2 for c-myc G-quadruplex DNA was over 200 times larger than that for telomere G-quadruplex DNA.     

N-Alkylated galanthamine derivatives: Potent acetylcholinesterase inhibitors from Leucojum aestivum

N-(14-Methylallyl)norgalanthamine, a new natural compound, together with five known alkaloids: N-allylnorgalanthamine, galanthamine, epinorgalanthamine, narwedine, and lycorine were isolated from mother liquors (waste material) obtained after industrial production of galanthamine hydrobromide from Leucojum aestivum leaves. The structures of N-allylnorgalanthamine and N-(14-methylallyl)norgalanthamine were completely determined by (1)H and (13)C NMR spectroscopy and two-dimensional experiments. N-allylnorgalanthamine (IC(50)=0.18microM) and N-(14-methylallyl)norgalanthamine (IC(50)=0.16microM) inhibit AChE considerably more than the approved drug galanthamine (IC(50)=1.82microM).