Cycloalkylpyranones and cycloalkyldihydropyrones as HIV protease inhibitors: exploring the impact of ring size on structure-activity relationships

Construction of cyclopenta[b]pyran-2-ones via chemoselective (3 + 2) cycloaddition between 2-pyrones and vinyl cyclopropanes

A chemoselective (3 + 2) cycloaddition of 2-pyrones and vinyl cyclopropanes for efficient and diastereoselective synthesis of cyclopenta[b]pyran-2-ones.

Synthesis of 2-amino-3-ethoxycarbonyl-4-aryl-4H,5H-pyrano-[3,2-c]benzopyran-5-one

A series of 2-amino-3-ethoxycarbonyl-4-aryl-4 H,5 H-pyrano-[3,2- c]benzopyran-5-ones have been were synthesised by the reaction of 4-hydroxycoumarin, an aromatic aldehyde and ethyl cyanoacetate under microwave irradiation with short times and high yields.

Synthesis of 4H,5H-pyrano[3,2-c][1]benzopyran-5-ones in aqueous media

The reaction of substituted cinnamonitriles with 4-hydroxycoumarin in water in the presence of triethylbenzyl-ammonium chloride affords 2-amino-4-aryl-4H,5H-pyrano [3,2-c] [1]benzopyran-5-one derivatives.

Pharmaceutical and medicinal significance of sulfur (SVI)-Containing motifs for drug discovery: A critical review

Sulfur (S^VI) based moieties, especially, the sulfonyl or sulfonamide based analogues have showed a variety of pharmacological properties, and its derivatives propose a high degree of structural diversity that has established useful for the finding of new therapeutic agents. The developments of new less toxic, low cost and highly active sulfonamides containing analogues are hot research topics in medicinal chemistry. Currently, more than 150 FDA approved Sulfur (S^VI)-based drugs are available in the market, and they are widely used to treat various types of diseases with therapeutic power. This comprehensive review highlights the recent developments of sulfonyl or sulfonamides based compounds in huge range of therapeutic applications such as antimicrobial, anti-inflammatory, antiviral, anticonvulsant, antitubercular, antidiabetic, antileishmanial, carbonic anhydrase, antimalarial, anticancer and other medicinal agents. We believe that, this review article is useful to inspire new ideas for structural design and developments of less toxic and powerful Sulfur (S^VI) based drugs against the numerous death-causing diseases.

Therapeutic potential of coumarins as antiviral agents

Coumarins have received a considerable attention in the last three decades as a lead structures for the discovery of orally bioavailable non-peptidic antiviral agents. A lot of structurally diverse coumarins analogues were found to display remarkable array of affinity with the different molecular targets for antiviral agents and slight modifications around the central motif result in pronounced changes in its antiviral spectrum. This manuscript thoroughly reviews the design, discovery and structure-activity relationship studies of the coumarin analogues as antiviral agents focusing mainly on lead optimization and its development into clinical candidates.

Antibacterial, antifungal and cytotoxic properties of novel N-substituted sulfonamides from 4-hydroxycoumarin

A new series of 4-({[2, 4-dioxo-2H-chromen-3 (4H)-ylidene] methyl} amino) sulfonamides have been obtained by the condensation reaction of 4-hydroxycoumarin with various sulfonamides (sulfanilamide, sulfaguanidine, p-aminomethyl-sufanilamide, p-aminoethylsufanilamide, sulfathiazole, sulfamethoxazole, sulfamethazine and 4-[(2-amino-4-pyrimidinyl) amino] benzenesulfonamide) in the presence of an excess of ethylorthoformate. These compounds were screened for their in-vitro antibacterial activity against four Gram-negative (E. coli, S. flexneri, P. aeruginosa and S. typhi) and two Gram-positive (B. subtilis and S. aureus) bacterial strains and for in-vitro antifungal activity against T. longifusus, C. albicans, A. flavus, M. canis, F. solani and C. glaberata. Results revealed that a significant antibacterial activity was observed by compounds (4) and (5), (6) and (8) against two Gram-negative, (P. aeruginosa and S. typhi) and two Gram-positive (B. subtilis and S. aureus) species, respectively. Of these (4) was found to be the most active. Similarly, for antifungal activity compounds (3) and (8) showed significant activity against M. canis and, (6) and (8) against F. solani. The brine shrimp bioassay was also carried out to study their in-vitro cytotoxic properties and only two compounds, (4) and (8) possessing LD50 = 2.9072 x 10(-4) and 3.2844 x 10(-4) M, respectively, displayed potent cytotoxic activity against Artemia salina

In-vitro antibacterial, antifungal and cytotoxic activities of some coumarins and their metal complexes

A series of new antibacterial and antifungal coumarin-derived compounds and their transition metal complexes [cobalt (II), copper (II), nickel (II) and zinc (II)] have been synthesized, characterized and screened for their in vitro antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae, Bacillus cereus, Corynebacterium diphtheriae, Staphylococcus aureus and Streptococcus pyogenes bacterial strains and for in vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani, Candida glaberata. The results of these studies show the metal complexes to be more antibacterial and antifungal as compared to the uncomplexed coumarins. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties.

Synthesis of 2-Amino-4-Aryl-5-Oxo-4,5-Dihydropyrano[3,2-c] Chromene Derivatives Catalysed by KF-Montmorillonite

A series of 2-amino-4-aryl-5-oxo-4,5-dihydropyrano[3,2- c]chromene derivatives has been synthesised by the reaction of 4-hydroxycoumarin and substituted cinnamonitriles catalysed by KF-montmorillonite. The structures were characterised by IR and 1H NMR spectroscopic data and confirmed by X-ray diffraction analysis.

Development of a Library of 6-Arylcoumarins as Candidate Fluorescent Sensors

[structure: see text]. A bromocoumarin scaffold (1) was reacted with various boronic acid derivatives (2a-l) to afford a library of 6-arylcoumarins (3a-l). This library was found to contain candidate fluorescent sensors for peptidase activity and for nitric oxide.

Probabilistic Neural Network Model for the In Silico Evaluation of Anti-HIV Activity and Mechanism of Action

A theoretical model has been developed that discriminates between active and nonactive drugs against HIV-1 with four different mechanisms of action for the active drugs. The model was built up using a probabilistic neural network (PNN) algorithm and a database of 2720 compounds. The model showed an overall accuracy of 97.34% in the training series, 85.12% in the selection series, and 84.78% in an external prediction series. The model not only correctly classified a very heterogeneous series of organic compounds but also discriminated between very similar active/nonactive chemicals that belong to the same family of compounds. More specifically, the model recognized 96.02% of nonactive compounds, 94.24% of active compounds that inhibited reverse transcriptase, 97.24% of protease inhibitors, 97.14% of virus uncoating inhibitors, and 90.32% of integrase inhibitors. The results indicate that this approach may represent a powerful tool for modeling large databases in QSAR with applications in medicinal chemistry.

Synthesis and biological screening of 7-hydroxy-4-methyl-2H-chromen-2-one, 7-hydroxy-4,5-dimethyl-2H-chromen-2-one and their some derivatives

7-Hydroxy-4-methyl-2H-chromen-2-one (2), 7-hydroxy-4,5-dimethyl-2H-chromen-2-one (15) and their some derivatives were synthesized for exploring selected biological screening. The compounds 9 and 13 had shown high degree of cytotoxic activity. Three compound 9, 10 and 13 showed high degree of bactericidal activity amongst the present series.

Structure-based discovery of Tipranavir disodium (PNU-140690E): a potent, orally bioavailable, nonpeptidic HIV protease inhibitor

Efforts to develop therapeutically relevant HIV protease inhibitors as medicinal agents in confronting the AIDS crisis have been aided by the wealth of fundamental information acquired during related drug discovery campaigns against other aspartyl proteases. This knowledge base was brought to full force with the broad screening identification of small, nonpeptidic, inhibitory molecules as templates for chemical elaboration. Significantly, the ability to collect crystallographic data on the inhibitor-enzyme complexes in a rapid fashion afforded the opportunity for a structure-based approach to drug discovery. Iterative cycles of synthesis, biological testing, and structural information gathering followed by prudent design modifications afforded compounds suitable for clinical evaluation. Displaying high enzymatic inhibition (Ki = 8 pM), potent in vitro antiviral cell culture activity (IC90 = 100 nM), and a useful pharmacokinetic profile, PNU-140690E (Tipranavir disodium) has entered into clinical studies. Promising results from these early trials supported further evaluation of this compound in HIV-infected individuals. PNU-140690E is currently under extensive clinical study.

Quantitative structure-activity relationships of some HIV-protease inhibitors

A quantitative structure-activity relationship (QSAR) study has been made on different series of cycloalkylpyranones acting as human-immunodeficiency-virus type 1 (HIV-1) protease inhibitors. The results suggest that the enzyme binding affinity of the compounds would be favoured by a cyclooctyl ring, a 3-cyclopropylphenylmethyl substituent at the pyranone ring, and a 4-CN-2-pyridine-, an N-Me-imidazole-, or a 3- or 4-CN-phenyl-sulfonamide group at the meta position of the phenyl ring of the 3-substituent.

4-hydroxy-5,6-dihydropyrones. 2. Potent non-peptide inhibitors of HIV protease

The 4-hydroxy-5,6-dihydropyrone template was utilized as a flexible scaffolding from which to build potent active site inhibitors of HIV protease. Dihydropyrone 1c (5,6-dihydro-4-hydroxy-6-phenyl-3-[(2-phenylethyl)thio]-2H-pyran-2-one) was modeled in the active site of HIV protease utilizing a similar binding mode found for the previously reported 4-hydroxybenzopyran-2-ones. Our model led us to pursue the synthesis of 6,6-disubstituted dihydropyrones with the aim of filling S1 and S2 and thereby increasing the potency of the parent dihydropyrone 1c which did not fill S2. Toward this end we attached various hydrophobic and hydrophilic side chains at the 6-position of the dihydropyrone to mimic the natural and unnatural amino acids known to be effective substrates at P2 and P2'. Parent dihydropyrone 1c (IC50 = 2100 nM) was elaborated into compounds with greater than a 100-fold increase in potency [18c, IC50 = 5 nM, 5-(3,6-dihydro-4-hydroxy-6-oxo-2-phenyl-5-[2-phenylethyl)thio] -2H-pyran-2-yl)pentanoic acid and 12c, IC50 = 51 nM, 5,6-dihydro-4-hydroxy-6-phenyl-6-(2-phenylethyl)-3- [(2-phenyl-ethyl)thio]-2H-pyran-2-one]. Optimization of the 3-position fragment to fill S1' and S2' afforded potent HIV protease inhibitor 49 [IC50 = 10 nM, 3-[(2-tert-butyl-5-methylphenyl)sulfanyl]-5,6-dihydro-4 -hydroxy-6-phenyl-6-(2-phenylethyl)-2H-pyran-2-one]. The resulting low molecular weight compounds (< 475) have one or no chiral centers and are readily synthesized.

Structure-based design of nonpeptidic HIV protease inhibitors: the sulfonamide-substituted cyclooctylpyramones

Recently, cyclooctylpyranone derivatives with m-carboxamide substituents (e.g. 2c) were identified as potent, nonpeptidic HIV protease inhibitors, but these compounds lacked significant antiviral activity in cell culture. Substitution of a sulfonamide group at the meta position, however, produces compounds with excellent HIV protease binding affinity and antiviral activity. Guided by an iterative structure-based drug design process, we have prepared and evaluated a number of these derivatives, which are readily available via a seven-step synthesis. A few of the most potent compounds were further evaluated for such characteristics as pharmacokinetics and toxicity in rats and dogs. From this work, the p-cyanophenyl sulfonamide derivative 35k emerged as a promising inhibitor, was selected for further development, and entered phase I clinical trials.