DFT-based QSAR study of testosterone and its derivatives

QSAR study of derivatives of testosterone has been made with the help of quantum mechanical parameters such as Absolute Hardness (eta) and Electronegativity (chi). These two parameters have been derived with the help of density functional theory. The 3-D modeling and geometry optimization of all the compounds have been done with the help of PCMODEL software and semiempirical PM3 calculations performed with the help of WinMOPAC-7.21 software. The absolute hardness provides valuable information due to maximum hardness principle and used in development of QSAR. The information provided by electronegativity is not as clear as in case of absolute hardness.     

QSAR study of flavonoid derivatives as p56lck tyrosinkinase inhibitors

QSAR studies on 104 flavonoid derivatives as p56lck protein tyrosine kinase inhibitors were performed using hydration energy and logP as predictor parameters. The results obtained demonstrate in detail, which specify that hydration energy and hydrophobic parameters of the compounds play a significant role in developing QSAR models. The significance of presence and absence of substituents on particular position is successfully explored with the help of indicator parameters. The results are critically discussed on the basis of multiple linear regression parameters.     

Deoxamuscaroneoxime derivatives as useful muscarinic agonists to explore the muscarinic subsite: demox, a modulator of orthosteric and allosteric sites at cardiac muscarinic M2 receptors

A series of muscarinic agonists, straight chained, branched, cyclic alkyl and aromatic derivatives of the oxime 1 (demox) was designed with the aim of investigating their activity on muscarinic receptor subtypes. Effects on M1 receptor were assessed functionally by a microphysiometer apparatus, while M2, M3, and M4 receptor potency and affinity were studied on isolated preparations of guinea pig heart, ileum, and lung, respectively. The results suggest that the substitution of a hydrogen with a long side-chain or bulky group generally induces a decrease in potency at M1 and M3 subtypes, while a general increase in this parameter is obtained at M2 subtype. Among the agonists 2-18, compound 4 behaves as a full agonist with a preference for M3 subtype. Moreover, compound 12 is inactive at M1 and M4 receptors while it displays a full agonist activity at M2 and M3 subtypes. Since demox displays a variable response on cardiac M2 receptors regulating heart force, an in-depth inquiry of the functional behaviour of this compound was carried out at M2 receptors. In presence of 10(-11) and 10(-10) M demox, the binding of [3H]-NMS was increased by approximately 30% as a consequence of an increase of the association of [3H]-NMS to membranes; this effect was not observed in presence of a higher concentration of [3H]-NMS. Higher concentrations of demox decreased the binding of [3H]-NMS to heart atrial membranes but significantly retarded the dissociation of this radioligand. Our results suggest that demox may interact with orthosteric and allosteric sites of atrial M2 muscarinic receptor.     

Discovery of N-sulfonyl-7-azaindoline derivatives as potent,orally available and selective M4 muscarinic acetylcholine receptor agonists

We designed and synthesized novel N-sulfonyl-7-azaindoline derivatives as selective M₄ muscarinic acetylcholine receptor agonists. Modification of the N-carbethoxy piperidine moiety of compound 2, an M₄ muscarinic acetylcholine receptor (mAChR)-preferring agonist, led to compound 1, a selective M₄ mAChR agonist. Compound 1 showed a highly selective M₄ mAChR agonistic activity with weak hERG inhibition in vitro. A pharmacokinetic study of compound 1 in vivo revealed good bioavailability and brain penetration in rats. Compound 1 reversed methamphetamine-induced locomotor hyperactivity in rats (1–10 mg/kg, po).     

Phenylacetic acid derivatives as hPPAR agonists

Beginning with the weakly active lead structure 1, a new series of hPPAR agonists was developed. In vivo glucose and triglyceride lowering activity was obtained by homologation and oxamination to 3, then conversion to substituted benzisoxazoles 4 and 5. Further manipulation afforded benzofurans 6 and 7. Compound 7 was of comparable potency as a glucose and triglyceride lowering agent in insulin resistant rodents to BRL 49653.     

Identification of N-substituted 8-azatetrahydroquinolone derivatives as selective and orally active M1 and M4 muscarinic acetylcholine receptors agonists

We designed and synthesized N-substituted 8-azatetrahydroquinolone derivatives as selective M₁ and M₄ muscarinic acetylcholine receptors agonists. Optimization of selected derivatives led to the discovery of compound 7 as a highly potent M₁ and M₄ agonist with weak hERG inhibition. Oral administration of compound 7 improved psychosis-like behavior in rats.     

Effect of novel N-aryl sulfonamide substituted 3-morpholino arecoline derivatives as muscarinic receptor 1 agonists in Alzheimer's dementia models

A series of novel, potent, and selective muscarinic receptor 1 agonists (M1 receptor agonists) that employ a key N-substituted morpholine Arecoline moiety has been synthesized as part of research effort for the therapy of Alzheimer’s diseases. The ester group of arecoline (which is reported as muscarinic agonist) has been replaced by N-substituted morpholine ring. The structure–activity relationship reveals that the electron donating 4-substituted sulfonyl derivatives (9a, 9b, 9c, and 9e) on the nitrogen atom of the morpholine ring increases the affinity of M1 receptor binding 50- to 80-fold greater than the corresponding arecoline. Other derivatives also showed considerable M1 receptor binding affinity.     

QSAR analysis of pyrazolidine-3,5-diones derivatives as Dyrk1A inhibitors

Individuals with Down syndrome (DS) suffer from mental retardation. Overexpression and the resulting increased specific activity of Dyrk1A kinase located on chromosome 21 cause a learning and memory deficit in Dyrk1A transgenic mice. To search for therapeutic agents with Dyrk1A inhibition activity, previously we obtained HCD160 as a new hit compound for Dyrk1A inhibition. In the present study, we synthesized 34 HCD160 derivatives to investigate the quantitative structure–activity relationship (QSAR). This analysis could provide important information for novel drug discovery for treatment of DS related learning and memory deficits.     

Discovery of N-substituted 7-azaindoline derivatives as potent,orally available M1 and M4 muscarinic acetylcholine receptors selective agonists

We designed and synthesized novel N-substituted 7-azaindoline derivatives as selective M₁ and M₄ muscarinic acetylcholine receptors (mAChRs) agonists. Hybridization of compound 2 with the HTS hit compound 5 followed by optimization of the N-substituents of 7-azaindoline led to identification of compound 1, which showed highly selective M₁ and M₄ mAChRs agonistic activity, weak human ether-a-go-go related gene inhibition, and good bioavailability in multiple animal species.     

Novel quinuclidinyl heteroarylcarbamate derivatives as muscarinic receptor antagonists

Herein, we describe the synthesis and pharmacological profiles of novel quinuclidinyl heteroarylcarbamate derivatives. Among them, the quinuclidin-4-yl thiazolylcarbamate derivative ASP9133 was identified as a promising long-acting muscarinic antagonist (LAMA) showing more selective inhibition of bronchoconstriction against salivation and more rapid onset of action in a rat model than tiotropium bromide.     

Synthesis of 3'-acetamidoadenosine derivatives as potential A3 adenosine receptor agonists

On the basis of high binding affinity of 3'-aminoadenosine derivatives 2b at the human A3 adenosine receptor (AR), 3'-acetamidoadenosine derivatives 3a-e were synthesized from 1,2:5,6-di-O-isopropylidene-D-glucose via stereoselective hydroboration as a key step. Although all synthesized compounds were totally devoid of binding affinity at the human A3AR, our results revealed that 3'-position of adenosine can only be tolerated with small size of a hydrogen bonding donor like hydroxyl or amino group in the binding site of human A3AR.     

Interaction of phencyclidine and its new adamantyl derivatives with muscarinic receptors

The antimuscarinic potency of new derivatives of phencyclidine containing the adamantyl moiety was evaluated in the guinea pig ileum test. The drugs tested competitively inhibited the acetylcholine-induced contractions. K_d values were calculated and compared to those obtained by direct binding to the muscarinic receptors from mouse brain. The new derivative, |1-(2-phenyl-2-adamantyl) piperidine| was found to be the most potent muscarinic antagonist among the many phencyclidine derivatives known to date. The results are discussed in terms of the acetylcholine-like molecular arrangement of these derivatives that gives rise to a characteristic muscarinic interaction.     

Discovery and synthesis of novel luteolin derivatives as DAT agonists

Luteolin, 5,7-dihydroxy-2-(3,4-dihydroxyphenyl)-4H-chromen-4-one, has been proposed and proved to be a novel dopamine transporter (DAT) activator. In order to develop this potential of luteolin, a series of novel luteolin derivatives were designed, synthesized, and evaluated for their DAT agonistic activities, utilizing constructed Chinese hamster ovary (CHO) cell lines stably expressing rat DAT. Biological screening results demonstrated that luteolin derivatives 1d, 1e, and 4c carry great DAT agonistic potency (EC(50)=0.046, 0.869, and 1.375μM, respectively) compared with luteolin 8 (EC(50)=1.45±0.29μM). Luteolin derivative 1d, notably, exhibited a 32-fold-higher DAT agonistic potency than luteolin. These luteolin derivatives represent a novel DAT agonist class, from which lead compounds useful for exploration of additional novel DAT agonists could be drawn.     

7-Azaindole derivatives as potential partial nicotinic agonists

We have investigated a series of 7-azaindoles as potential partial agonists of the alpha4beta2 nicotinic acetylcholine receptor (nAChR). Three series of 7-azaindole derivatives have been synthesized and evaluated for rat brain neuronal nicotinic receptor affinity and functional activity. Compound (+)-51 exhibited the most potent nAChR binding (Ki = 10 nM). Compound 30A demonstrated both moderate binding affinity and partial agonist potency, thus representing a promising lead for the indications of cognition and smoking cessation.     

Binding of agonists and antagonists to muscarinic receptors

The binding of one irreversible and two reversible radioactive antagonists to muscarinic receptors in synaptosome preparations of rat cerebral cortex has been studied. The ligands all bind to the same receptor pool and directly and competitively yield self-consistent binding constants closely similar to those obtained by pharmacological methods on intact smooth muscle. The binding process for antagonists seems to be a simple mass action-determined process with a Hill slope of 1.0. The quantitative correlations strongly support the view that the receptor studied by ligand binding corresponds to the receptor studied by pharmacological methods. Inhibition of antagonist binding by most agonists shows a reduced Hill slope which also applies to direct binding studies of [³H] acetylcholine. Mechanisms that might account for the behavior of agonists are discussed but do not conclusively point to any single mechanism.