Design, synthesis and biological evaluation of triazole-oxadiazole conjugates for the management of cognitive dysfunction.

Acetylcholinesterase has been a promising target for the development of putative therapeutics against cognitive decline. The deleterious effect of oxidative stress on the learning and memory paradigms of an individual has also been well documented. In view of this, the present study demonstrates the design, synthesis and pharmacological evaluation of triazole-oxadiazole conjugates. Eighteen novel hybrids (6-23) have been synthesised by employing suitable synthetic procedures and characterized by various spectral and elemental techniques. Further these synthesised compounds were evaluated against behavioural alterations using step down passive avoidance and escape learning protocol at a dose of 0.5 mg/kg with reference to the standard, donepezil. All the synthesised compounds were evaluated for their in vitro acetylcholinesterase (AChE) inhibition at five different concentrations using mice brain homogenate as the source of the enzyme. Biochemical estimation of markers of oxidative stress (lipid peroxidation, superoxide dismutase, glutathione and catalase) has also been carried out to assess the role of synthesised molecules on the oxidative damage induced by scopolamine. The compounds 13, 17 and 23 displayed appreciable activity towards acetylcholinesterase inhibition. These compounds also decreased scopolamine induced oxidative stress, thus serving as promising leads for the amelioration of oxidative stress induced cognitive decline. The molecular docking study performed to predict the binding mode of the compounds also suggested that these compounds bind appreciably to the amino acids present in the active site of the recombinant human acetylcholinesterase (rhAChE). The results indicated that these compounds could be further traversed as inhibitors of AChE and oxidative stress for the treatment of cognitive dysfunction.

Design, synthesis and pharmacological evaluation of some novel indanone derivatives as acetylcholinesterase inhibitors for the management of cognitive dysfunction.

The present study reports the effect of indanone derivatives on scopolamine induced deficit cholinergic neurotransmission serving as promising leads for the therapeutics of cognitive dysfunction. Eleven compounds 54-64 have been designed, synthesised and evaluated against behavioural alterations using step down passive avoidance protocol at a dose of 0.5 mg/kg with Donepezil (1) as the reference standard. All the synthesised compounds were evaluated for their in vitro acetylcholinesterase (AChE) inhibition at five different concentrations using mice brain homogenate as the source of the enzyme. Compounds 54, 56, 59 and 64 displayed appreciable activity with an IC50 value of 14.06 µM, 12.30 µM, 14.06 µM and 12.01 µM, respectively towards acetylcholinesterase inhibition. The molecular docking study performed to predict the binding mode of the compounds suggested that these compounds could bind appreciably to the amino acids present at the active site of recombinant human acetylcholinesterase (rhAChE). The behavioural, biochemical and in silico pharmacokinetic studies were in concordance with each other.

Design and synthesis of benzimidazole-based Rho kinase inhibitors for the treatment of glaucoma.

Rho kinase inhibitors (ROCK II) play a key role in glaucoma management attributed to their IOP lowering ability and neuroprotective effects. In the present study, a series of novel benzimidazole derivatives (9a-m) has been synthesized and evaluated for their IOP lowering, Rho kinase inhibitory and antioxidant properties. The synthesized compounds were found to be lipophilic and showed a significant IOP lowering effect both in the treated and the contralateral eye comparable to the reference standard fasudil. The nitrophenyl piperazine substituted compound 9j exhibited significant IOP lowering (51.56%) and an inhibition of 57.25 and 77.92% towards ROCK II enzyme at a concentration of 0.5 and 1 mM respectively. It possessed a considerable free radical scavenging activity exhibiting an IC50 value of 95.49 µg/mL in DPPH assay. The molecular docking studies of compound 9j indicated the binding of the compound at the active site of recombinant human ROCK II which makes it a promising antiglaucoma agent.

Coumarin derivatives as potential inhibitors of acetylcholinesterase: Synthesis, molecular docking and biological studies.

A series of novel hybrids has been synthesized by linking coumarin moiety through an appropriate spacer to various substituted heterocyclic amines and evaluated as dual binding site acetylcholinesterase inhibitors for the treatment of cognitive dysfunction caused by increased hydrolysis of acetylcholine and scopolamine induced oxidative stress. Anti-amnesic activity of the compounds was evaluated using Morris water maze model at a dose of 1mg/kg with reference to the standard, donepezil. Biochemical estimation of oxidative stress markers (lipid peroxidation, superoxide dismutase, and plasma nitrite) was carried out to assess the antioxidant potential of the synthesized molecules. Among all the synthesized compounds (15a-i, 16a-d, 17a-b), compound 15a [4-[3-(4-phenylpiperazin-1-yl)propoxy]-2H-chromen-2-one] displayed significant antiamnesic activity, AChE inhibitory activity (IC50=2.42µM) and antioxidant activity in comparison to donepezil (IC50=1.82µM). Molecular docking study of 15a indicated that it interacts with all the crucial amino acids present at the CAS, mid-gorge and PAS of TcAChE resulting in increased inhibition of AChE enzyme.

Current pharmacotherapy and putative disease-modifying therapy for Alzheimer's disease.

Alzheimer's disease (AD) is an age-related neurodegenerative disease of the central nervous system correlated with the progressive loss of cognition and memory. ß-Amyloid plaques, neurofibrillary tangles and the deficiency in cholinergic neurotransmission constitute the major hallmarks of the AD. Two major hypotheses have been implicated in the pathogenesis of AD namely the cholinergic hypothesis which ascribed the clinical features of dementia to the deficit cholinergic neurotransmission and the amyloid cascade hypothesis which emphasized on the deposition of insoluble peptides formed due to the faulty cleavage of the amyloid precursor protein. Current pharmacotherapy includes mainly the acetylcholinesterase inhibitors and N-methyl-D-aspartate receptor agonist which offer symptomatic therapy and does not address the underlying cause of the disease. The disease-modifying therapy has garnered a lot of research interest for the development of effective pharmacotherapy for AD. ß and γ-Secretase constitute attractive targets that are focussed in the disease-modifying approach. Potentiation of α-secretase also seems to be a promising approach towards the development of an effective anti-Alzheimer therapy. Additionally, the ameliorative agents that prevent aggregation of amyloid peptide and also the ones that modulate inflammation and oxidative damage associated with the disease are focussed upon. Development in the area of the vaccines is in progress to combat the characteristic hallmarks of the disease. Use of cholesterol-lowering agents also is a fruitful strategy for the alleviation of the disease as a close association between the cholesterol and AD has been cited. The present review underlines the major therapeutic strategies for AD with focus on the new developments that are on their way to amend the current therapeutic scenario of the disease.

Design and synthesis of newer potential 4-(N-acetylamino)phenol derived piperazine derivatives as potential cognition enhancers.

A series of novel hybrids has been designed, synthesized and evaluated for cognition enhancing activities through the inhibition of acetylcholinesterase (AChE) and by passive avoidance mouse model. All the compounds showed excellent AChE inhibition activities and potentially reversed the scopolamine induced memory deficit. Enzyme kinetic and molecular docking studies have confirmed their dual binding affinity and mixed type inhibition. Among them, compounds 1b and 2d displayed excellent IC50 values of 1.66µM and 0.49µM and competitive inhibitor constant Ki 43.66µM and 4.10µM respectively. Ex vivo study confirmed their CNS penetration and brain AChE inhibition abilities. Furthermore, 1b and 2d showed significant antiamnesic activity at a dose of 1.0mg/kg as compared to the reference compounds piracetam and rivastigmine. The results indicate that these two compounds emerged to be developed as cognition enhancers worthy of future pursuit.

Acridine: A Scaffold for the Development of Drugs for Alzheimer's Disease.

Alzheimer's disease (AD) is drawing scientists' consideration, being one of the gravest diseases mankind will have to battle against in the near future. The number of people with AD is expected to triple in the next 40 years. It is a most common age-related multifactorial neurodegenerative disease and characterized by two histopathological hallmarks; the formation of senile plaques composed of the amyloid-ß (Aß) peptide and neurofibrillary tangles composed of hyperphosphorylated tau protein. Discovery and development of rationally designed multi-targeted ligands for the management of AD could be more beneficial than classical single targeted molecules. Acridine, a heterocyclic nucleus is a sole moiety in various existing drug molecules such as quinacrine (antimalarial), acriflavine and proflavine (antiseptics), ethacridine (abortifacient), amsacrine and nitracine (anticancer) and tacrine (anti-Alzheimer). It is proposed that acridine may combat the AD by acting on several targets like acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), dual specificity tyrosine kinase 1A (Dyrk 1A), amyloid and prion protein (PrPC) etc. involved in its pathogenesis. The main aim of this compilation is to review the most promising therapeutic developments within the vast research area dealing with acridine derivatives. Further research is required to evaluate the effectiveness of the acridine derivatives with various substitutions in the treatment of AD. In conclusion, our review will suggest the potentiality of the versatile acridine framework for drug designing and developing novel multi-target inhibitors for the Alzheimer's disease.

1,3,4-Thiadiazole: A Versatile Pharmacophore of Medicinal Significance.

The 1,3,4-thiadiazole nucleus has attracted the attention of medicinal chemists during the last decades due to its multiple pharmacological activities, such as antiviral, anticancer, antibacterial, and anticonvulsant activity. This scaffold's structural alteration could aid in developing novel therapeutically effective drugs. Incorporating this adaptable pharmacophore into a well-established medicinally active molecule results in hybrid molecules with diverse pharmacological effects. These encouraging reports suggested that this privileged skeleton should be thoroughly researched for medicinal purposes. Hence, an attempt has been made in this compilation to review the structure-activity relationships of numerous thiadiazole derivatives reported in the literature with varied pharmacological properties. This review provides an up-to-date explanation of the various synthesized 1,3,4- thiadiazole analogs and their pharmacological importance.

Recent Development of DNA Gyrase Inhibitors: An Update.

Antibiotic or antimicrobial resistance is an urgent global public health threat that occurs when bacterial or fungal infections do not respond to the drug regimen designed to treat these infections. As a result, these microbes are not evaded and continue to grow. Antibiotic resistance against natural and already-known antibiotics like Ciprofloxacin and Novobiocin can be overcome by developing an agent that can act in different ways. The success of agents like Zodiflodacin and Zenoxacin in clinical trials against DNA gyrase inhibitors that act on different sites of DNA gyrase has resulted in further exploration of this target. However, due to the emergence of bacterial resistance against these targets, there is a great need to design agents that can overcome this resistance and act with greater efficacy. This review provides information on the synthetic and natural DNA gyrase inhibitors that have been developed recently and their promising potential for combating antimicrobial resistance. The review also presents information on molecules that are in clinical trials and their current status. It also analysed the SAR studies and mechanisms of action of enlisted agents.

Molecular docking and receptor-specific 3D-QSAR studies of acetylcholinesterase inhibitors.

The reversible inhibition of acetylcholinesterase (AChE) has become a promising target for the treatment of Alzheimer's disease (AD) which is mainly associated with low in vivo levels of acetylcholine (ACh). The availability of AChE crystal structures with and without a ligand triggered the effort to find a structure-based design of acetylcholinesterase inhibitors (AChEIs) for AD. The major problem observed with the structure-based design was the feeble robustness of the scoring functions toward the correlation of docking scores with inhibitory potencies of known ligands. This prompted us to develop new prediction models using the stepwise regression analysis based on consensus of different docking and their scoring methods (GOLD, LigandFit, and GLIDE). In the present investigation, a dataset of 91 molecules belonging to 9 different structural classes of heterocyclic compounds with an activity range of 0.008 to 281,000 nM was considered for docking studies and development of AChE-specific 3D-QSAR models. The model (M1) developed using consensus of docking scores of scoring functions viz. Glide score, Gold score, Chem score, ASP score, PMF score, and DOCK score was found to be the best (R(2) = 0.938, Q(2) = 0.925, R(pred)(2) = 0.919, R(2)m((overall)) = 0.936) compared to other consensus models. Docking studies revealed that the molecules with proper alignment in the active site gorge and the ability to interact with all the crucial amino acid residues, in particular by forming π-π stacking interactions with Trp84 at the catalytic anionic site (CAS) and Trp279 at peripheral anionic site (PAS), showed augmented potencies with consequent improvement in patient cognition and reduced the formation of senile plaques associated with AD. Further, the descriptors that signify the association of the ligands with the receptor as well as ADME properties of the ligands were also analyzed by means of the set of ligands that have been pre-positioned with respect to a receptor after docking analysis and considered as independent variables to generate a linear model (M3 and M4) using a stepwise multiple linear regression method to get additional insight into the physicochemical requirements for effective binding of ligands with AChE as well as for prediction of AChE inhibition. The developed AChE-specific prediction models (M1-M4) satisfactorily reflect the structure-activity relationship of the existing AChEIs and have all the potential to facilitate the process of design and development of new potent AChEIs.

N-[4-(2-Morpholino-eth-oxy)phen-yl]acetamide monohydrate.

In the title compound, C(14)H(20)N(2)O(3)·H(2)O, the geometry about the morpholine N atom implies sp(3) hybridization. In the crystal, symmetry-related mol-ecules are linked by inter-molecular N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonds, forming infinite chains along the b axis. The chain structure is further stabilized by intra-molecular C-H⋯O inter-actions.

Systematic In Silico Design, Synthesis, and Biological Studies of Some Novel 1,4-Benzoquinone Derivatives for the Prospective Management of Cognitive Decline.

Cholinesterases are significant biological targets for the regulation of cholinergic neurotransmission, and their inhibitors are being exploited for the management of cognitive decline in various neurological conditions. The 1,4-benzoquinone scaffold possesses antioxidant potential along with AChE inhibition activity in various neurological disorders. To design novel and potent selective 1,4-benzoquinone analogues as cholinesterase inhibitors, a ligand-based drug design strategy was followed to develop a 3D quantitative structure-selectivity relationship (QSSR) model. On the basis of the best fit model, eight novel 1,4-benzoquinone derivatives were designed and synthesized implementing appropriate synthetic procedures and were characterized by various spectral and elemental techniques. All the synthesized compounds were evaluated for their selective in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory potential at different concentrations using mice brain homogenate as the source of the enzyme. Out of these compounds, the three most selective compounds were further evaluated for behavioral variations using step down passive avoidance and escape learning procedure at a dose of 0.5 mg/kg taking donepezil as the reference drug. Biochemical estimation of the markers of oxidative stress (lipid peroxidation, superoxide dismutase, glutathione, and catalase) has also been carried out to determine the role of the synthesized molecules on the scopolamine induced oxidative damage. Compound 2a displayed appreciable selectivity index values as predicted through the 3D-QSSR model. Further, docked complexes of compound 2a with AChE and BChE were subjected to molecular dynamic simulations for a period of 30 ns to study the orientations and stable conformations of the most active molecules in the catalytic domain of these enzymes. The results obtained from the 3D-QSSR analysis, docking, and molecular dynamic studies were found to be appreciable and provided a deep insight into the structural features required for the selectivity of AChE inhibitors over BChE. The outcome of this study may be used as a novel tool to design new highly selective and more potent molecules.

p-Benzoquinone as a Privileged Scaffold of Pharmacological Significance: A Review.

Quinones are a huge class of compounds with affluent and captivating chemistry. p-Benzoquinone (p-BNZ) or 1,4-Benzoquinone is the key structural motif of numerous biologically active synthetic and natural compounds. This draws interest in its biological exploration to assess prospective therapeutic implications. It possesses immense therapeutic potential depending on different substitutions. This moiety has a marvelous potential to regulate a varied range of different cellular pathways which can be investigated for various selective activities. p-Benzoquinones have been a requisite core for the development of novel therapeutic molecules with minimum side effects. In this review, various synthetic, pharmacological approaches and structure-activity relationship studies focusing on the chemical groups responsible for evoking the pharmacological potential of p-benzoquinone derivatives have been emphasized. Additionally, the compilation highlights the chemical, pharmaceutical and medicinal aspects of synthetic and natural benzoquinone derivatives. The natural occurrences of p-benzoquinone derivatives with different pharmacological significance have also been reported in this review.

Investigation of Molecular Properties of Antiretroviral Agents to Enhance CNS Penetration Abilities for the Treatment of Cognitive Impairment in HIV-Associated Neurocognitive Disorder.

HIV-associated neurocognitive disorder (HAND) can be represented by neurological and neuropathological abnormalities with a consequence of motor and cognitive loss. It has become a critical unmet medical need for infected people, and the number continues to rise every year. Pathological investigations have revealed its occurrence due to the release of free radicals from the HIV infected microglia and macrophages. So far, no effective clinical trials have been conducted for its treatment other than the use of some antiretroviral therapies which have failed to show good results due to poor CNS penetration and hence low CNS distribution. This collective information from the updated literature reports motivated us to share the idea of conjugated products of antiretroviral agents and antioxidants leading to better brain penetration abilities due to higher log p values, higher molecular weight and possibly low toxicity and better neuroprotective action. In this Viewpoint, we have attempted to analyze the chemical and pharmacological classes of antiretroviral agents (ARAs) and their clinical failures for the treatment of cognitive dysfunction due to HIV infection. As the causes of clinical insufficiency of antiretroviral agents and neuropathological mechanisms of HAND have been well established, it would be a good opportunity for medicinal chemists to develop new potential antiretroviral agents or to improve their molecular properties for better therapeutic implications. Furthermore, in silico based molecular properties have been investigated correlating them to the brain penetration abilities.

Rho-kinase (ROCK) Inhibitors - A Neuroprotective Therapeutic Paradigm with a Focus on Ocular Utility.

BACKGROUND: Glaucoma is a progressive optic neuropathy causing visual impairment and Retinal Ganglionic Cells (RGCs) death gradually posing a need for neuroprotective strategies to minimize the loss of RGCs and visual field. It is recognized as a multifactorial disease, Intraocular Pressure (IOP) being the foremost risk factor. ROCK inhibitors have been probed for various possible indications, such as myocardial ischemia, hypertension, kidney diseases. Their role in neuroprotection and neuronal regeneration has been suggested to be of value in the treatment of neurological diseases, like spinal-cord injury, Alzheimer's disease and multiple sclerosis but recently Rho-associated Kinase inhibitors have been recognized as potential antiglaucoma agents. EVIDENCE SYNTHESIS: Rho-Kinase is a serine/threonine kinase with a kinase domain which is constitutively active and is involved in the regulation of smooth muscle contraction and stress fibre formation. Two isoforms of Rho-Kinase, ROCK-I (ROCK ß) and ROCK-II (ROCK α) have been identified. ROCK II plays a pathophysiological role in glaucoma and hence the inhibitors of ROCK may be beneficial to ameliorate the vision loss. These inhibitors decrease the intraocular pressure in the glaucomatous eye by increasing the aqueous humour outflow through the trabecular meshwork pathway. They also act as anti-scarring agents and hence prevent post-operative scarring after the glaucoma filtration surgery. Their major role involves axon regeneration by increasing the optic nerve blood flow which may be useful in treating the damaged optic neurons. These drugs act directly on the neurons in the central visual pathway, interrupting the RGC apoptosis and therefore serve as a novel pharmacological approach for glaucoma neuroprotection. CONCLUSION: Based on the results of high-throughput screening, several Rho kinase inhibitors have been designed and developed comprising of diverse scaffolds exhibiting Rho kinase inhibitory activity from micromolar to subnanomolar ranges. This diversity in the scaffolds with inhibitory potential against the kinase and their SAR development will be intricated in the present review. Ripasudil is the only Rho kinase inhibitor marketed to date for the treatment of glaucoma. Another ROCK inhibitor AR-13324 has recently passed the clinical trials whereas AMA0076, K115, PG324, Y39983 and RKI-983 are still under trials. In view of this, a detailed and updated account of ROCK II inhibitors as the next generation therapeutic agents for glaucoma will be discussed in this review.

Exploring the Chemistry and Therapeutic Potential of Triazoles: A Comprehensive Literature Review.

Triazole is a valuable platform in medicinal chemistry, possessing assorted pharmacological properties, which could play a major role in the common mechanisms associated with various disorders like cancer, infections, inflammation, convulsions, oxidative stress and neurodegeneration. Structural modification of this scaffold could be helpful in the generation of new therapeutically useful agents. Although research endeavors are moving towards the growth of synthetic analogs of triazole, there is still a lot of scope to achieve drug discovery break-through in this area. Upcoming therapeutic prospective of this moiety has captured the attention of medicinal chemists to synthesize novel triazole derivatives. The authors amalgamated the chemistry, synthetic strategies and detailed pharmacological activities of the triazole nucleus in the present review. Information regarding the marketed triazole derivatives has also been incorporated. The objective of the review is to provide insights to designing and synthesizing novel triazole derivatives with advanced and unexplored pharmacological implications.

beta-adrenoreceptor blocking and antihypertensive activity of PP-24, a newly synthesized aryloxypropanolamine derivative.

PP-24 is a newly synthesized putative beta-adrenoceptor antagonist. The objective of the study was to the evaluate beta-adrenoceptor blocking activity of PP-24 on isolated rat preparations: right atria, uterus and colon. Effects on the rat ECG and renal hypertension (induced by left renal artery ligation) were also investigated. Treatment with PP-24 (3 and 10 mg kg(-1)) for 7 days in rats with renal hypertension significantly reduced the mean atrial blood pressure. Single i.v. injections of isoprenaline (0.3, 1 and 3 microg kg(-1)) alone in normal anaesthetized rat caused hypotension and tachycardia, while PP-24 alone produced dose-dependent falls in mean aterial pressure and bradycardia. Pretreatment of anaesthetized rats with test compounds significantly blocked the hypotension response but not the tachycardia induced by isoprenaline (0.3, 1 and 3 microg kg(-1)). The pA(2) of PP-24 to beta(1)-, beta(2)- and beta(3)-adrenoceptors was 7.72 +/- 0.082, 7.40 +/- 0.082 and 6.39 +/- 0.16, respectively. The beta(1)/beta(2) selectivity ratio was 2.08, compared with 1.27 for propranolol and 39.17 for atenolol. It is concluded that PP-24 possesses beta-adrenoceptor blockade activity but with non-specific affinity for beta(1)- and beta(2)-adrenoceptor subtypes. The rank order of potency of the antagonists for beta(1)-adrenoceptors was atenolol > PP-24 > propranolol. The antihypertensive activity of PP-24 in rats with renal hypertension appears to be due to blockade of beta-adrenoceptors.

N-(4-Hydroxyphenyl)-3,4,5-trimethoxybenzamide derivatives as potential memory enhancers: synthesis, biological evaluation and molecular simulation studies.

The present paper describes the synthesis, biological evaluation and molecular simulation studies of a series of N-(4-hydroxyphenyl)-3,4,5-trimethoxybenzamide derivatives with N,N-dialkylaminoethoxy/propoxy moiety as potential memory enhancers with acetylcholinesterase-inhibiting activity having IC50 in low micromolar range (4.0-16.5 µM). All the compounds showed a good degree of agreement between in vivo and in vitro results as most of these derivatives showed dose-dependent increase in percent retention. Compound 10a showed significant % retention of 84.73 ± 4.51 as compared to piracetam (46.88 ± 5.42) at 3 mg kg-1 and also exhibited a maximal percent inhibition of 97% at 50 µM. Molecular docking, MM-GBSA and molecular simulation studies were performed establishing a correlation between the experimental biology and in silico results. In silico results indicate that all the compounds have better docking scores and predicted binding free energies as compared to cocrystallized ligand with the best potent ligand retaining conserved hydrophobic interactions with residues of catalytic triad (HIS447), catalytic anionic site (CAS) (TRP86, TYR337, PHE338) and peripheral anionic site (PAS) (TYR72, TYR124, TRP286 and TYR341). Root mean square deviation (RMSD = 2.4 Å) and root mean square fluctuations of 10a-AChE complex during simulation proved its stable nature in binding toward acetylcholinesterase. The docked conformation of 10a and other analogs at the binding site have also been simulated with polar and nonpolar interactions interlining the gorge residues from PAS to catalytic triad.

Towards better brain management: nootropics.

The learning and memory deficits have been recognized as severe and consistent neurological disorders associated with numerous neurodegenerative states. Research in this area has gained momentum only in the recent past after the biochemical and physiological basis of these processes have been understood. A considerable alteration in the neurotransmission is a consistent finding in cognitive disorders. Therefore, many therapeutic strategies to augment the concentration of neurotransmitters in brain such as cholinergic agents, biogenic amines and neuropeptides etc. have been evaluated in cognitive deficits. CNS modulators are the type of antiamnesics that act via modulation of the neurological processes underlying memory storage. These include psychostimulants, excitatory amino acids and most important of all "nootropics". Nootropics are a heterogeneous group of compounds of diverse chemical composition and biological function that allegedly facilitate learning and memory or overcome natural or induced cognitive impairments. The literature survey incorporated in this article hallmarks the success achieved in the design and development of potential nootropic agents. Additionally, this review is an attempt towards discussing various approaches available to enhance memory, along with the classification of the known memory enhancers, authors research work towards various structural modifications carried out and the biological screening.

Beta-blocking activity of PP-34, a newly synthesized aryloxypropanolamine derivative, and its cardioprotective effect against ischaemia/reperfusion injury in laboratory animals.

Beta-adrenoceptor antagonists are widely used in cardiovascular medicine. However, the main side effect of these drugs is due to antagonism of beta(2)-adrenoceptors in the airways, resulting in bronchospasm. Therefore, more cardioselective beta-blockers have been developed to offer a lower side effect profile. We have studied a new aryloxypropanolamine derivative (PP-34) with more cardioselectivity and efficacy against ischaemia/reperfusion injury in rats. Oxalate salts of 1-(tert-butylamino)-3-(5-tert-butylaminomethyl-2-methoxyphenoxy) propan-2-ol (PP-34) is a novel beta-adrenoceptor antagonist. In-vitro studies in rat isolated right atria, guinea-pig trachea and rat distal colon preparations were carried out to investigate the potency of PP-34 towards different beta-adrenoceptor subtypes. pA(2)/pK(B) values of PP-34 for beta(1), beta(2), and beta(3) adrenoceptor were 7.89+/-0.15, 6.13+/-0.09 and 6.30+/-0.19, respectively. The beta(1)/beta(2) selectivity ratio calculated was in the order of PP-34 > atenolol > propranolol. Pre-ischaemic administration (20 min before coronary occlusion) of PP-34 (0.3 or 1 mg kg(-1)) showed cardioprotective effects against ischaemia/reperfusion injury in rats and significantly reduced arrhythmias, infarct area and necrosis induced by ischaemia/reperfusion injury. The efficacy of PP-34 was found to be greater then atenolol. In conclusion, PP-34 is a cardioselective beta-adrenoceptor antagonist, possessing potent anti-arrhythmic and cardioprotective effects against ischaemia/reperfusion injury in rats.