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.     

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.     

4‐Substituted‐1‐phenyl‐1H‐pyrazolo[3,4‐d]pyrimidine Derivatives: Design,Synthesis, Antitumor and EGFR Tyrosine Kinase Inhibitory Activity

Four series of some 4‐substituted‐1‐phenyl‐1H‐pyrazolo[3,4‐d]pyrimidine derivatives 5a – f , 6a – f , 8a – f , and 9a – f were designed to be screened for their antitumor activity. All compounds were evaluated against breast (MCF‐7) and lung (A‐549) cell lines. Six compounds 5a , 5b , 6b , 6e , 9e , and 9f displaying activity against both cell lines were further estimated for their EGFR‐TK inhibitory activity where they revealed 41–91% inhibition and compound 6b elicited the highest activity (91%). A docking study of these compounds into the ATP‐binding site of EGFR‐TK demonstrated their binding mode where H‐bonding interaction with Met793 through N¹ of pyrimidine or N² of pyrazole was observed.     

Amino Acid Derivatives,Part 4: Synthesis and Anti‐HIV Activity of New Naphthalene Derivatives

A new series of 2‐(naphthalen‐2‐yloxy)‐N‐[(aryl‐5‐thioxo‐4,5‐dihydro‐1H‐1,2,4‐triazol‐3‐yl)methyl] acetamides 5a–f was synthesized from naphthalene‐derived glycine derivative 2 via the hydrazinoacetamide analogs 4a–f . Alternatively, treatment of 4a with H₂SO₄ afforded 2‐(naphthalen‐2‐yloxy)‐N‐((5‐(phenylamino)‐1,3,4‐thiadiazol‐2‐yl)methyl) acetamide 6a . Alkylation or sulphonylation of 5a afforded the S‐alkylated derivatives 7 and 8 , respectively. Interestingly, treatment of 3 with methoxide ion gave the triazine derivative 9 . The synthesized compounds have been screened for their inhibitory activity against HIV‐1 and HIV‐2 in MT‐4 cells. However, 7 was found to be the potent inhibitor in vitro for the replication of HIV‐1 (EC₅₀ = 0.20 μg/mL), suggesting a new lead in the development of an antiviral agent.     

Synthesis,In Vitro Protoporphyrinogen Oxidase Inhibition,and Herbicidal Activity of N‐(Benzothiazol‐5‐yl)hexahydro‐1H‐isoindole‐1,3‐diones and N‐(Benzothiazol‐5‐yl)hexahydro‐1H‐isoindol‐1‐ones

Protoporphyrinogen oxidase ( EC 1.3.3.4 ) is one of the most significant targets for a large family of herbicides. As part of our continuous efforts to search for novel protoporphyrinogen oxidase‐inhibiting herbicides, N‐(benzothiazol‐5‐yl)tetrahydroisoindole‐1,3‐dione was selected as a lead compound for structural optimization, leading to the syntheses of a series of novel N‐(benzothiazol‐5‐yl)hexahydro‐1H‐isoindole‐1,3‐diones ( 1a – o ) and N‐(benzothiazol‐5‐yl)hexahydro‐1H‐isoindol‐1‐ones ( 2a – i ). These newly prepared compounds were characterized by elemental analyses, ¹H NMR, and ESI‐MS, and the structures of 1h and 2h were further confirmed by X‐ray diffraction analyses. The bioassays indicated that some compounds displayed comparable or higher protoporphyrinogen oxidase inhibition activities in comparison with the commercial control. Very promising, compound 2a , ethyl 2‐((6‐fluoro‐5‐(4,5,6,7‐tetrahydro‐1‐oxo‐1H‐isoindol‐2(3H)‐yl)benzo[d]thiazol‐2‐yl)‐sulfanyl)acetate, was recognized as the most potent candidate with K_i value of 0.0091 μm . Further greenhouse screening results demonstrated that some compounds exhibited good herbicidal activity against Chenopodium album at the dosage of 150 g/ha.     

Design,Synthesis, and Biological Evaluation of 1‐(thiophen‐2‐yl)‐9H‐pyrido[3,4‐b]indole Derivatives as Anti‐HIV‐1 Agents

A novel series of 1‐(thiophen‐2‐yl)‐9H‐pyrido [3,4‐b]indole derivatives were synthesized using DL‐tryptophan as starting material. All the compounds were characterized by spectral analysis such as ¹H NMR, Mass, IR, elemental analysis and evaluated for inhibitory potency against HIV‐1 replication. Among the reported analogues, compound 7g exhibited significant anti‐HIV activity with EC₅₀ 0.53 μm and selectivity index 483; compounds 7e , 7i , and 7o displayed moderate activity with EC₅₀ 3.8, 3.8, and 2.8 μm and selectivity index >105, >105, and 3.85, respectively. Interestingly, compound 7g inhibited p24 antigen expression in acute HIV‐1_IIIB infected cell line C8166 with EC₅₀ 1.1 μm . In this study, we also reported the Lipinski rule of 5 parameters, predicted toxicity profile, drug‐likeness, and drug score of the synthesized analogues.     

4‐amino‐6‐alkyloxy‐2‐alkylthiopyrimidine derivatives as novel non‐nucleoside agonists for the adenosine A1 receptor

Three 4‐amino‐6‐alkyloxy‐2‐alkylthiopyrimidine derivatives ( 4 – 6 ) were investigated as potential non‐nucleoside agonists at human adenosine receptors (ARs). When tested in competition binding experiments, these compounds exhibited low micromolar affinity (K_i values comprised between 1.2 and 1.9 μm ) for the A₁ AR and no appreciable affinity for the A_2A and A₃ ARs. Evaluation of their efficacy profiles by measurement of intracellular cAMP levels revealed that 4 and 5 behave as non‐nucleoside agonists of the A₁ AR with EC₅₀ values of 0.47 and 0.87 μm , respectively. No clear concentration‐response curves could be instead obtained for 6 , probably because this compound modulates one or more additional targets, thus masking the putative effects exerted by its activation of A₁ AR. The three compounds were not able to modulate A_2B AR‐mediated cAMP accumulation induced by the non‐selective AR agonist NECA, thus demonstrating no affinity toward this receptor.     

Some Hydrazones of 2‐Aroylamino‐3‐methylbutanohydrazide: Synthesis,Molecular Modeling Studies,and Identification as Stereoselective Inhibitors of HIV‐1

In accordance with our antiviral drug development attempt, acylhydrazone derivatives bearing amino acid side chains were synthesized for the evaluation of their antiviral activity against various types of viruses. Among these compounds, 8 _S , 11 _S , and 12 _S showed anti‐HIV‐1 activity with a 50% inhibitory concentration (IC₅₀) = 123.8 µM (selectivity index, SI > 3), IC₅₀ = 12.1 µM (SI > 29), IC₅₀ = 17.4 µM (SI > 19), respectively. Enantiomers 8 _R , 11 _R , and 12 _R were inactive against the HIV‐1 strain III_B. Hydrazones 8 _S , 11 _S , and 12 _S which were active against HIV‐1 wild type showed no inhibition against a double mutant NNRTI‐resistant strain (K103N;Y181C). Molecular docking calculations of R‐ and S‐enantiomers of 8 , 11 , and 12 were performed using the hydrazone‐bound novel site of HIV‐1 RT.     

1,2,3,4‐Tetrahydroisoquinolines as inhibitors of HIV‐1 integrase and human LEDGF/p75 interaction

Alkaloids are a class of organic compounds with a wide range of biological properties, including anti‐HIV activity. The 1,2,3,4‐tetrahydroisoquinoline is a ubiquitous structural motif of many alkaloids. Using a short and an efficient route for synthesis, a series of 1,2,3,4‐tetrahydroisoquinolines/isoquinolines was developed. These compounds have been analysed for their ability to inhibit an important interaction between HIV‐1 integrase enzyme (IN) and human LEDGF/p75 protein (p75) which assists in the viral integration into the active genes. A lead compound 6d is found to inhibit the LEDGF/p75‐IN interaction in vitro with an IC₅₀ of ~10 μm . Molecular docking analysis of the isoquinoline 6d reveals its interactions with the LEDGF/p75‐binding residues of IN. Based on an order of addition experiment, the binding of 6d or LEDGF/p75 to IN is shown to be mutually exclusive. Also, the activity of 6d in vitro is found to be unaffected by the presence of a non‐specific DNA. As reported earlier for the inhibitors of LEDGF/p75‐IN interaction, 6d exhibits a potent inhibition of both the early and late stages of HIV‐1 replication. Compound 6d differing from the known inhibitors in the chemical moieties and interactions with CCD could potentially be explored further for developing small molecule inhibitors of LEDGF/p75‐IN interaction having a higher potency.     

Synthesis and Antifungal Activity of 1‐Aryl‐3‐phenethylamino‐1‐propanone Hydrochlorides and 3‐Aroyl‐4‐aryl‐1‐phenethyl‐4‐piperidinols

Mono‐Mannich bases, 1‐aryl‐3‐phenethylamino‐1‐propanone hydrochlorides, 1a, 2a , 3a , 4a , 5a , 6a , 7a , 8a , 9a , and semi‐cyclic mono‐Mannich bases, 3‐aroyl‐4‐aryl‐1‐phenethyl‐4‐piperidinols, 1b , 2b , 3b , 4b , 5b , 6b , 7b , 8b , 9b , were synthesized by a non‐classical Mannich reaction. The aryl part was: C₆H₅ for 1a , 1b ; 4‐CH₃C₆H₄ for 2a , 2b ; 4‐CH₃OC₆H₄ for 3a , 3b ; 4‐ClC₆H₄ for 4a , 4b ; 4‐FC₆H₄ for 5a , 5b ; 4‐BrC₆H₄ for 6a , 6b ; 2,4‐(Cl)₂C₆H₃ for 7a , 7b ; 4‐NO₂C₆H₄ for 8a , 8b ; and C₄H₃S(2‐yl) i. e., 2‐thienyl for 9a , 9b . Piperidinol compounds 2b , 3b , 4b , 5b , 7b , 8b , and 9b are reported here for the first time. The synthesized compounds were tested against seven types of plant pathogenic fungi and three types of human pathogenic fungi using the agar dilution assay. Itraconazole was tested against Candida parapsilosis as the reference compound, while Nystatin was tested as the reference compound against the other fungi. Compounds 1a , 1b , 2a , 4a , 4b , 5a , 5b , 6a , 7a , 8a , 9a , and 9b can be selected as model compounds to develop new antifungal agents against the human pathogen Microsporum canis. Compounds 8a and 8b , which had a similar antifungal activity compared with the reference compound Nystatin against the plant pathogen Aspergillus flavus, can serve as model compounds to develop new antifungal agents to solve agricultural problems.     

Synthesis of Novel Pyrimidin‐4‐One Bearing Piperazine Ring‐Based Amides as Glycogen Synthase Kinase‐3β Inhibitors with Antidepressant Activity

Novel pyrimidin‐4‐one derivatives have been synthesized using EDC coupling and evaluated as glycogen synthase kinase‐3β (GSK‐3β) inhibitors. Among all the synthesized compounds, compound 5 (3‐methyl‐6‐phenyl‐2‐(piperazin‐1‐yl)‐3,4‐dihydropyrimidin‐4‐one) exhibited the most potent inhibitory activity against GSK‐3β with IC₅₀ value of 74 nm . The molecular docking studies were performed to elucidate the binding modes of the compounds with the target, and a crucial interaction involving hydrogen bond formation with Val‐135 to the active site of GSK‐3β was observed. Furthermore, the synthesized compounds were subjected to in vivo evaluation of their antidepressant activity, and compound 5 showing highest inhibition of GSK‐3β was also found to significantly reduce the duration of immobility at 50 mg/kg, when compared with fluoxetine, a known antidepressant drug. The results of our study suggest that compound 5 may serve as a valuable template for the design and development of inhibitors of GSK‐3β with antidepressant activity.