Zaman Ashraf

Quinazolines and quinazolinones as ubiquitous structural fragments in medicinal chemistry: An update on the development of synthetic methods and pharmacological diversification

Nitrogen-rich heterocycles, particularly quinazolines and quinazolinones, represent a unique class of diversified frameworks displaying a broad spectrum of biological functions. Over the past several years, intensive medicinal chemistry efforts have generated numerous structurally functionalized quinazoline and quinazolinone derivatives. Interest in expanding the biological effects, demonstrated by these motifs, is growing exponentially, as indicated by the large number of publications reporting the easy accessibility of these skeletons in addition to the diverse nature of synthetic as well as biological applications. Therefore, the main focus of the present review is to provide an ample but condensed overview on various synthetic approaches providing access to quinazoline and quinazolinone compounds with multifaceted biological activities. Furthermore, mechanistic insights, synthetic utilization, structure-activity relationships and molecular modeling inputs for the potent derivatives have also been discussed.

Efficient synthesis of some 3-substuited-1(2H)-isoquinolones

A number of 3-aryl-1(2H)-isoquinolones were efficiently prepared from the corresponding 3-arylisocoumarins by refluxing with methanamide.

Design, synthesis and bioevaluation of novel umbelliferone analogues as potential mushroom tyrosinase inhibitors

Abstract A series of umbelliferone analogues were synthesized and their inhibitory effects on the DPPH and mushroom tyrosinase were evaluated. The results showed that some of the synthesized compounds exhibited significant mushroom tyrosinase inhibitory activities. Especially, 2-oxo-2-[(2-oxo-2H-chromen-7-yl)oxy]ethyl-2,4-dihydroxybenzoate (4e) bearing 2,4-dihydroxy substituted phenyl ring exhibited the most potent tyrosinase inhibitory activity with IC50 value 8.96 µM and IC50 value of kojic acid is 16.69. The inhibition mechanism analyzed by Lineweaver–Burk plots revealed that the type of inhibition of compound 4e on tyrosinase was non-competitive. The docking study against tyrosinase enzyme was also performed to determine the binding affinity of the compounds. The compounds 4c and 4e showed the highest binding affinity with active binding site of tyrosinase. The initial structure activity relationships (SARs) analysis suggested that further development of such compounds might be of interest. The statistics of our results endorses that compounds 4c and 4e may serve as a structural template for the design and development of novel tyrosinase inhibitors.

Iminothiazoline-Sulfonamide Hybrids as Jack Bean Urease Inhibitors; Synthesis, Kinetic Mechanism and Computational Molecular Modeling

The present work reports the synthesis of several 2‐iminothiazoline derivatives of sulfanilamide (3a–j) as inhibitors of jack bean ureases. The title compounds were synthesized by the heterocyclization of sulfanilamide thioureas with propragyl bromide in dry ethanol in the presence of 1,8‐Diazabicyclo[5.4.0]undec‐7‐ene as a base. All of the compounds showed higher urease inhibitory activity than the standard thiourea. The compounds (3h) and (3i) exhibited excellent enzyme inhibitory activity with IC50 0.064 and 0.058 μm, respectively, while IC50 of thiourea is 20.9 μm. The kinetic mechanism analyzed by Dixon plot showed that compound (3h) is a mixed‐type inhibitor while (3i) is a competitive one. Docking studies suggested that Asp633, Ala636, His492, Ala440, Lue523, Asp494 and Arg439 are the major interacting residues in the binding site of the protein and may have an instrumental role in the inhibition of enzymes function. 2‐iminothiazoline analogues (3a–j) showed good docking score (−10.6466 to −8.7215 Kcal/mol) and binding energy (London dG ranging from −14.4825 to −10.4087 Kcal/mol) which is far better than the standard thiourea (binding score in S field −4.5790 Kcal/mol London dG −4.7726 Kcal/mol). Our results inferred compound (3i) may serve as a structural model for the design of most potent urease inhibitors.

Metal-catalyzed synthesis of isocoumarin derivatives (microreview)

Isocoumarins (1H-isochromen-1-ones), an important class of naturally occurring unsaturated lactones, exhibit a broad range of pharmacological activities including cytotoxicity toward HeLa cervical cancer cells,1 antioxidant activity in HepG2 cells exposed to oxidative stress conditions induced by H2O2,2 antiangiogenic,3 anticancer,4,5 antifungal,6,7 and antimicrobial activity.8 Isocoumarins are also important building blocks for the synthesis of a number of medicinally important heterocycles.9–11 A number of conventional methods have been used for the synthesis of isocoumarins starting from homophthalic acids,12,13 but metal-catalyzed synthesis of isocoumarins has attracted considerable attention due to its economic advantages and good functional group tolerance.14,15 Recent reports on the Cu-, Pd-, Ru-, and Rh-catalyzed synthesis of isocoumarins are reviewed here. Besides, an example of Re catalysis has appeared recently.16

Influence of plasma-activated compounds on melanogenesis and tyrosinase activity

Many organic chemists around the world synthesize medicinal compounds or extract multiple compounds from plants in order to increase the activity and quality of medicines. In this work, we synthesized new eugenol derivatives (ED) and then treated them with an N2 feeding gas atmospheric pressure plasma jet (APPJ) to increase their utility. We studied the tyrosinase-inhibition activity (activity test) and structural changes (circular dichroism) of tyrosinase with ED and plasma activated eugenol derivatives (PAED) in a cell-free environment. Later, we used docking studies to determine the possible interaction sites of ED and PAED compounds with tyrosinase enzyme. Moreover, we studied the possible effect of ED and PAED on melanin synthesis and its mechanism in melanoma (B16F10) cells. Additionally, we investigated the structural changes that occurred in activated ED after plasma treatment using nuclear magnetic resonance (NMR). Hence, this study provides a new perspective on PAED for the field of plasma medicine.

First macrocyclic 3rd-generation ALK inhibitor for treatment of ALK/ROS1 cancer: Clinical and designing strategy update of lorlatinib

Non-small cell lung cancers (NSCLC) harboring anaplastic lymphoma kinase (ALK) gene rearrangements invariably develop resistance to 2nd-generation ALK inhibitors. Lorlatinib (PF-06463922) (6) is a 3rd-generation macrocyclic ALK-TKI that demonstrates many advantages over 2nd-generation ALK inhibitors. Lorlatinib has demonstrated decent kinase selectivity, promising pharmacokinetic profile, selective brain-penetration and strong antiproliferative activity in several ALK/ROS1-driven tumor models. The current review describes the activity spectrum, key events from discovery to clinical applications and the evidences that lorlatinib acts as an ALK/ROS1 inhibitor in clinical settings.

Design, synthesis and docking studies of some novel isocoumarin analogues as antimicrobial agents

A number of novel isocoumarin analogues have been synthesized by the condensation of homophthalic acid anhydride with different non-steroidal anti-inflammatory drugs (NSAIDs). To investigate the antimicrobial data on a structural basis, in silico docking studies of the synthesized compounds (4a–4g) into the crystal structure of UDP-N-acetylmuramate-L-alanine ligase using an Autodock PyRx virtual screening program were performed in order to predict the affinity and orientation of the synthesized compounds at the activities. UDP-N-acetylmuramate-L-alanine ligase is essential for D-glutamate metabolism and peptidoglycan biosynthesis in bacteria. R2 values showed good agreement with predicted binding affinities obtained by molecular docking studies. The results indicate that the basic nucleic portion of the (4c), (4g), (4f) and (4a) binds into the specificity pocket. In this pocket, the isocoumarin nucleus of these compounds interacts with the amino acid residue of the target. Moreover, it is verified by in vitro antimicrobial screening, in which all of the compounds were active against tested bacterial strains. Among these compounds (4c), (4g), (4f) and (4a) showed good bacterial zone inhibition.

Synthesis, enzyme inhibitory kinetics, and computational studies of novel 1-(2-(4-isobutylphenyl) propanoyl)-3-arylthioureas as Jack bean urease inhibitors

In this article, synthesis of a novel 1‐(2‐(4‐isobutylphenyl)propanoyl)‐3‐arylthioureas (4a–j) as jack bean urease inhibitors has been described. Freshly prepared 2‐(4‐isobutylphenyl) propanoyl isothiocyanate was treated with substituted aromatic anilines in one pot using anhydrous acetone. The compounds 4e, 4h, and 4j showed IC50 values 0.0086 nm, 0.0081 nm, and 0.0094 nm, respectively. The enzyme inhibitory kinetics results showed that compound 4h inhibit the enzyme competitively while derivatives 4e and 4j are the mixed type inhibitors. The compound 4h reversibly binds the urease enzyme showing Ki value 0.0012 nm. The Ki values for 4e and 4j are 0.0025 nm and 0.003 nm, respectively. The antioxidant activity results reflected that compounds 4b, 4i, and 4j showed excellent radical scavenging activity. Moreover, the cytotoxic activity of the target compounds was evaluated using brine shrimp assay and it was found that all of the synthesized compounds exhibited no cytotoxic effects to brine shrimps. The computational molecular docking and molecular dynamic simulation of title compounds were also performed, and results showed that the wet laboratory findings are in good agreement to the dry laboratory results. Based upon our results, it is proposed that compound 4h may act as a lead candidate to design the clinically useful urease inhibitors.

Pharmacoinformatics exploration of polyphenol oxidases leading to novel inhibitors by virtual screening and molecular dynamic simulation study

Polyphenol oxidases (PPOs)/tyrosinases are metal-dependent enzymes and known as important targets for melanogenesis. Although considerable attempts have been conducted to control the melanin-associated diseases by using various inhibitors. However, the exploration of the best anti-melanin inhibitor without side effect still remains a challenge in drug discovery. In present study, protein structure prediction, ligand-based pharmacophore modeling, virtual screening, molecular docking and dynamic simulation study were used to screen the strong novel inhibitor to cure melanogenesis. The 3D structures of PPO1 and PPO2 were built through homology modeling, while the 3D crystal structures of PPO3 and PPO4 were retrieved from PDB. Pharmacophore modeling was performed using LigandScout 3.1 software and top five models were selected to screen the libraries (2601 of Aurora and 727, 842 of ZINC). Top 10 hit compounds (C1-10) were short-listed having strong binding affinities for PPO1-4. Drug and synthetic accessibility (SA) scores along with absorption, distribution, metabolism, excretion and toxicity (ADMET) assessment were employed to scrutinize the best lead hit. C4 (name) hit showed the best predicted SA score (5.75), ADMET properties and drug-likeness behavior among the short-listed compounds. Furthermore, docking simulations were performed to check the binding affinity of C1-C10 compounds against target proteins (PPOs). The binding affinity values of complex between C4 and PPOs were higher than those of other complexes (-11.70, -12.1, -9.90 and -11.20kcal/mol with PPO1, PPO2, PPO3, or PPO4, respectively). From comparative docking energy and binding analyses, PPO2 may be considered as better target for melanogenesis than others. The potential binding modes of C4, C8 and C10 against PPO2 were explored using molecular dynamics simulations. The root mean square deviation and fluctuation (RMSD/RMSF) graphs results depict the significance of C4 over the other compounds. Overall, bioactivity and ligand efficiency profiles suggested that the proposed hit may be more effective inhibitors for melanogenesis.