Design,Synthesis, and Biological Evaluation of Novel 4‐Aminopiperidinyl‐linked 3,5‐Disubstituted‐1,2,6‐thiadiazine‐1,1‐dione Derivatives as HIV‐1 NNRTIs

Based on the hybridization of the privileged fragments in DABO and DAPY‐typed HIV‐1 NNRTIs, a novel series of 4‐aminopiperidinyl‐linked 3,5‐disubstituted‐1,2,6‐thiadiazine‐1,1‐dione derivatives were designed, synthesized, and evaluated for their in vitro anti‐HIV activities in MT‐4 cells. Most of the target compounds showed weak inhibitory activity against WT HIV‐1. In order to confirm the mode of action of the target compounds, representative compounds Ba8 and Bb8 were selected to perform the HIV‐1 RT inhibitory assay. In this assay, Ba8 and Bb8 displayed good activity with IC₅₀ values of 3.15 and 1.52 μm , respectively. Additionally, preliminary structure–activity relationships (SARs) analysis and molecular docking studies of newly synthesized compounds are also discussed.     

Molecular Modeling,Synthesis, and Anti‐HIV Activity of Novel Isoindolinedione Analogues as Potent Non‐nucleoside Reverse Transcriptase Inhibitors

Different isoindolinedione derivatives bearing imine, amide, thioamide, and sulfonamide linkages have been designed in silico using discovery studio software (BIOVIA, San Diego, CA, USA), synthesized, and evaluated for their anti‐HIV activity. SAR studies revealed that the linkages in these molecules did affect their anti‐HIV activity and the molecules having sulfonamide linkages were the most potent HIV‐RT inhibitors as the S=O bonds of the sulfonamide moiety interacted with Lys103 (NH or carbonyl or both) and Pro236; the NH part of the sulfonamide linkage formed bond with carbonyl of Lys101. blood–brain barrier (BBB) plots were also studied, and it was found that all the designed molecules have potential to cross BBB, a very vital criteria for anti‐HIV drugs. In vitro screening was performed using HIV‐1 strain IIIB in MT‐4 cells using the MTT assay, and it was seen that some of these molecules were effective inhibitors of HIV‐1 replication at nanomolar concentration with selectivity indices ranging from 33.75 to 73.33 under in vitro conditions. Some of these molecules have shown good anti‐HIV activity at 3–4 nm concentrations. These derivatives have potential to be developed as lead molecules effective against HIV‐1. Novel isoindolinedione derivatives as probable NNRTIs have been synthesized and characterized. Some of these molecules have shown good anti‐HIV activity at 3–4 nm concentrations.     

Discovery of HIV‐1 Integrase Inhibitors: Pharmacophore Mapping,Virtual Screening,Molecular Docking,Synthesis, and Biological Evaluation

HIV‐1 integrase enzyme plays an important role in the life cycle of HIV and responsible for integration of virus into human genome. Here, both computational and synthetic approaches were used to design and synthesize newer HIV‐1 integrase inhibitors. Pharmacophore mapping was performed on 20 chemically diverse molecules using DISCOtech, and refinement was carried out using GASP. Ten pharmacophore models were generated, and model 2, containing four features including two donor sites, one acceptor atom, and one hydrophobic region, was considered the best model as it has the highest fitness score. It was used as a query in NCI and Maybridge databases. Molecules having more than 99% Q_fit value were used to design 30 molecules bearing pteridine ring and were docked on co‐crystal structure of HIV‐1 integrase enzyme. Among these, six molecules, showing good docking score compared with the reference standards, were synthesized by conventional as well as microwave‐assisted methods. All compounds were characterized by physical and spectral data and evaluated for in vitro anti‐HIV activity against the replication of HIV‐1 (IIIB) in MT‐4 cells. The used approach of molecular docking and anti‐HIV activity data of designed molecules will provide significant insights to discover novel HIV‐1 Integrase Inhibitors.     

Synthesis of Some N,N′‐Diacylhydrazine Derivatives with Radical‐Scavenging and Antifungal Activity

A series of N,N′‐diacylhydrazines were prepared and their structures were confirmed by ¹H NMR, MS and FTICR‐MS. They were tested radical‐scavenging activity in vitro. The preliminary bioassays of title compounds showed that two compounds had excellent radical‐scavenging activity comparable with vitamin C, while the activity is highly relative to the substituents. Surprisingly, several compounds also exhibit favorable fungicidal activities. To further explore the comprehensive structure–activity relationships about the fungicidal activity, a three‐dimensional quantitative structure–activity relationship analysis using the method of comparative molecular field analysis was performed.     

Synthesis and Evaluation of Novel 4‐Substituted Styryl Quinazolines as Potential Antimicrobial Agents

In an attempt to afford possible antibacterial and anti‐human immunodeficiency virus (HIV) agents, a series of 22 novel styryl quinazoline‐based heterocyclic entities were designed and synthesized. Various substituted aryl urea and thiourea cores were incorporated at position 4 of quinazoline, followed by styrylation of position 2, aiming at an augmented biological potential. The synthesized compounds were well characterized through IR, ¹H NMR, ¹³C NMR and elemental analyses. All compounds were screened for their in vitro anti‐HIV activity against the HIV‐1 (IIIB) and HIV‐2 (ROD) strains. The antibacterial activity was also evaluated against various pathogenic Gram‐positive and Gram‐negative bacterial strains.     

N‐hydroxy‐substituted 2‐aryl acetamide analogs: A novel class of HIV‐1 integrase inhibitors

An in silico method has been used to discover N‐hydroxy‐substituted 2‐aryl acetamide analogs as a new class of HIV‐1 integrase inhibitors. Based on the molecular requirements of the binding pocket of catalytic active site, two molecules (compounds 2 and 4b ) were designed as fragments. These were further synthesized and biologically evaluated. In vitro potency along with docking studies highlighted compound 4b as an active fragment which was further used to synthesize new leads as HIV‐1 integrase inhibitors. Finally, six promising compounds (compounds 5b , 5c , 5e, 6–2c, 6–3b, and 6–5b ) were identified by integrase inhibition assay (>50% inhibition). Based on in vitro anti‐HIV‐1 activity in a reporter gene‐based cell assay system, compounds 5d , 6s , and 6k were found as novel HIV‐1 integrase inhibitors due to its better selectivity index. Additionally, docking study revealed the importance of H‐bond as well as hydrophobic interactions with Asn155, Lys156, and Lys159 which were required for their anti‐HIV‐1 activity.     

Computational Study of CCR5 Antagonist with Support Vector Machines and Three Dimensional Quantitative Structure Activity Relationship Methods

CCR5 is the key receptor of HIV-1 virus entry into host cells and it becomes an attractive target for antiretroviral drug design. To date, six types of CCR5 antagonist were synthesized and evaluated. To search more potent bio-active compounds, non-linear support vector machine was used to construct the relationship models for 103 oximino-piperidino-piperidine CCR5 antagonists. Then, comparative molecular field analysis and comparative molecular similarity indices analysis models were constructed after alignment with their common substructure. Twenty-one structural diverse compounds, which were not included in the support vector machine, comparative molecular field analysis, and comparative molecular similarity indices analysis models, validated these models. The results show that these models possess good predictive ability. When comparing between support vector machine and 3D-quantitative structure activity relationship models, the results obtained from these two methods are compatible. However, 3D-quantitative structure activity relationship model is significantly better than support vector machine model and previous reported pharmacophore model. These models can help us to make quantitative prediction of their bio-activities before in vitro and in vivo stages.     

Discovery of 2‐(3,4‐dialkoxyphenyl)‐2‐(substituted pyridazin‐3‐yl)acetonitriles as phosphodiesterase 4 inhibitors with anti‐neuroinflammation potential based on three‐dimensional quantitative structure–activity relationship study

Phosphodiesterase 4 (PDE4) inhibitors with potential activities for CNS disorders provide a new therapeutic strategy for depression. To discover PDE4 inhibitors with anti‐neuroinflammation activities, reliable three‐dimensional quantitative structure‐activity relationship (3D‐QSAR) models on our previous reported catecholic PDE4 inhibitors was built with a statistically significant cross‐validated coefficient (q²), conventional coefficient (r²), and good predictive capabilities based on the molecular docking results, using comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA) methods. Based on the analysis of CoMFA and CoMSIA contour maps, a series of 2‐(3,4‐dialkoxyphenyl)‐2‐(substituted pyridazin‐3‐yl) acetonitriles 16a–i was designed and synthesized. Among these compounds, compound 16a exhibited good inhibitory activities toward PDE4B1 and PDE4D7 with mid‐nanomolar IC₅₀ values and potential anti‐neuroinflammation activity in BV‐2 cells. Docking simulation of compound 16a in the PDE4 catalytic domain activity pocket revealed that compound 16a maybe assumed a “V‐shaped” conformation, extending the side chain to S‐pocket.