Design,synthesis and biological evaluation of 3-benzyloxy-linked pyrimidinylphenylamine derivatives as potent HIV-1 NNRTIs

A novel series of 3-benzyloxy-linked pyrimidinylphenylamine derivatives (8a–8s) was designed, synthesized and evaluated for their in vitro anti-HIV activity in MT-4 cell cultures. Most of the compounds inhibited wild-type (wt) HIV-1 replication in the lower micromolar concentration range (EC₅₀ = 0.05–35 μM) with high selectivity index (SI) values (ranged from 10 to >4870). In particular, 8h and 8g displayed excellent antiretroviral activity against wt HIV-1 with low cytotoxicity (EC₅₀ = 0.07 μM, CC₅₀ >347 μM, SI >4870; EC₅₀ = 0.05 μM, CC₅₀ = 42 μM, SI = 777, respectively), comparable to that of the marked drug nevirapine (EC₅₀ = 0.113 μM, CC₅₀ >15 μM, SI >133). In order to confirm the binding target, 8h was selected to perform the anti-HIV-1 RT assay. Additionally, preliminary structure activity relationship (SAR) analysis and molecular docking studies of newly synthesized compounds were also discussed, as well as the predicted physicochemical properties.     

Design,synthesis and biological evaluation of novel acetamide-substituted doravirine and its prodrugs as potent HIV-1 NNRTIs

A novel series of acetamide-substituted derivatives and two prodrugs of doravirine were designed and synthesized as potent HIV-1 NNRTIs by employing the structure-based drug design strategy. In MT-4 cell-based assays using the MTT method, it was found that most of the new compounds exhibited moderate to excellent inhibitory potency against the wild-type (WT) HIV-1 strain with a minimum EC₅₀ value of 54.8?nM. Among them, the two most potent compounds 8i (EC₅₀?=?59.5?nM) and 8k (EC₅₀?=?54.8?nM) displayed robust activity against WT HIV-1 with double-digit nanomolar EC₅₀ values, being superior to lamivudine (3TC, EC₅₀?=?12.8?μM) and comparable to doravirine (EC₅₀?=?13?nM). Besides, 8i and 8k shown moderate activity against the double RT mutant (K103N?+?Y181C) HIV-1 RES056 strain. The HIV-1 RT inhibition assay further validated the binding target. Molecular simulation of the representative compounds was employed to provide insight on their structure-activity relationships (SARs) and direct future design efforts. Finally, the aqueous solubility and chemical stability of the prodrugs 9 and 10 were investigated in detail.     

Design, synthesis, and biological evaluation of chicoric acid analogs as inhibitors of HIV-1 integrase

A series of analogs of the potent HIV-1 integrase (HIV IN) inhibitor chicoric acid (CA) was designed with the intention of ameliorating some of the parent natural product's undesirable properties, in particular its toxicity, instability, and poor membrane permeability. More than 70 analogs were synthesized and assayed for three types of activity: (1) the ability to inhibit 3'-end processing and strand transfer reactions using recombinant HIV IN in vitro, (2) toxicity against the CD4+ lymphoblastoid cell line, MT2, and (3) anti-HIV activity against HIV(LAI). CA analogs lacking one of the carboxyl groups of CA and with 3,4,5-trihydroxycinnamoyl sidechains in place of the caffeoyl group of CA exhibited the most potent inhibition of HIV replication and end-processing activity. Galloyl-substituted derivatives also displayed very potent in vitro and in vivo activities, in most cases exceeding the inhibitory effects of CA itself. Conversely, analogous monocarboxy caffeoyl analogs exhibited only modest inhibition, while the corresponding 3,4-dihydroxybenzoyl-substituted compounds were devoid of activity.     

Design, synthesis, and biological evaluation of novel 4-hydroxypyrone derivatives as HIV-1 protease inhibitors

Twenty-four 4-hydroxypyrone derivatives were synthesized with a facile synthetic method to develop novel HIV protease inhibitors. Most of them were shown to display good antiviral activities in SIV-infected CEM cells. The introduction of alpha-naphthylmethyl group to C-6 of 5,6-dihydropyran-2-ones led to an effective antiviral compound that showed an EC(50) value at 1.7 microM with a therapeutic index of 46.     

Design,synthesis and biological evaluation of N2,N4-disubstituted-1,1,3-trioxo-2H,4H-pyrrolo[1,2-b][1,2,4,6]thiatriazine derivatives as HIV-1 NNRTIs

A series of N₂,N₄-disubstituted-1,1,3-trioxo-2H,4H-pyrrolo[1,2-b][1,2,4,6]thiatriazine derivatives (PTTDs) was designed and synthesized by a facile route. The biological assay results showed that five most potent compounds displayed inhibitory activity against HIV-1 at low micromolar concentrations (EC₅₀ = 5.1–8.9 μM). Structure–activity relationship analysis indicated that N₂-(3-halogenated-benzyl) analogues were more potent than N₂-(unsubstituted-benzyl) analogues. The N₄-substitutions contributed to the antiviral activity in the following order: 2-/3-cyano substituted benzyl > 2-/3-halogenated benzyl > non-substituted benzyl > 4-halogenated benzyl. Docking studies of the representative compound revealed the binding conformation of these compounds and provided critical insights for the further development of PTTD analogues.     

Fused heterocyclic compounds bearing bridgehead nitrogen as potent HIV-1 NNRTIs. Part 1: Design,synthesis and biological evaluation of novel 5,7-disubstituted pyrazolo[1,5-a]pyrimidine derivatives

In our continuous efforts to identify novel potent HIV-1 NNRTIs, a novel class of 5,7-disubstituted pyrazolo[1,5-a]pyrimidine derivatives were rationally designed, synthesized and evaluated for their anti-HIV activities in MT4 cell cultures. Biological results showed that most of the tested compounds displayed excellent activity against wild-type HIV-1 with a wide range of EC₅₀ values from 5.98 to 0.07 μM. Among the active compounds, 5a was found to be the most promising analogue with an EC₅₀ of 0.07 μM against wild-type HIV-1 and very high selectivity index (SI, 3999). Compound 5a was more effective than the reference drugs nevirapine (by 2-fold) and delavirdine (by 2-fold). In order to further confirm their binding target, an HIV-1 RT inhibitory assay was also performed. Furthermore, SAR analysis among the newly synthesized compounds was discussed and the binding mode of the active compound 5a was rationalized by molecular modeling studies.     

Arylazolyl(azinyl)thioacetanilides. Part 10: Design, synthesis and biological evaluation of novel substituted imidazopyridinylthioacetanilides as potent HIV-1 inhibitors

In continuation of our efforts toward the discovery of potent HIV-1 NNRTIs with novel structures, we have employed a scaffold hopping strategy to explore the chemically diversed space of bioactive compounds. The original arylazolylthioacetanilide platform was replaced with different imidazopyridinyl- thioacetanilide scaffolds to yield the optimal pharmacophore moieties in order to generate novel NNRTIs with desirable potency. Some of the new compounds proved able to inhibit HIV-1 replication in the low micromolar range. In particular, compound 5b16 displayed the most potent anti-HIV-1 activity (EC(50)=0.21±0.06μM), inhibiting HIV-1 IIIB replication in MT-4 cells more effectively than dideoxycytidine (EC(50)=1.4±0.1μM) and similarly with nevirapine (EC(50)=0.20±0.10μM). Preliminary structure-activity relationship (SAR) of the newly synthesized congeners is discussed, and molecular modeling study is performed to rationalize the SAR conclusions.     

Design,synthesis and biological evaluation of thienopyridinones as Chk1 inhibitors

A series of thienopyridinone derivatives was designed and synthesized as inhibitors of checkpoint kinase 1 (Chk1). Most of them exhibited moderate to good Chk1 inhibitory activities. Among them, compounds 8q, 8t, and 8w with excellent Chk1 inhibitory activities (IC₅₀ values of 4.05, 6.23, and 2.33 nM, respectively) displayed strong synergistic effects with melphalan, a DNA-damaging agent in the cell-based assay. Further kinase profiling indicated that compound 8t was highly selective against CDK2/cyclinA, Aurora A, and PKC.     

Design,synthesis and biological evaluation of novel HIV-1 protease inhibitors with pentacyclic triterpenoids as P2-ligands

The design, synthesis and SAR study of a new series of HIV-1 protease inhibitors with pentacyclic triterpenoids as P2 ligands and phenylsulfonamide as P2′ ligands were discussed. These compounds exhibited micromolar inhibitory potency, among which compound T1c displayed HIV-1 protease inhibition with IC₅₀ values of 0.12?μM, which was 67 times the inhibitory activity of its raw material Ursolic acid (8.0?μM).     

Synthesis and biological evaluation of novel 2-(substituted phenylaminocarbonylmethylthio)-6-(2,6-dichlorobenzyl)-pyrimidin-4(3H)-ones as potent HIV-1 NNRTIs

A series of novel 2-(phenylaminocarbonylmethylthio)-6-(2,6-dichlorobenzyl)-pyrimidin-4(3H)-ones have been designed and synthesized. All of the new compounds were evaluated for their anti-HIV activities in MT-4 cells. Most of these new compounds showed moderate to potent activities against wild-type HIV-1 with an EC₅₀ ranging from 4.48 μM to 0.18 μM. Among them, 2-[(4-bromophenylamino)carbonylmethylthio]-6-(2,6-dichlorobenzyl)-5-methylpyrimidin-4(3H)-one 4b3 was identified as the most promising compound (EC₅₀ = 0.18 ± 0.06 μM, CC₅₀ >243.56 μM, SI >1326). The structure–activity relationship (SAR) of these new congeners is discussed.     

The design, synthesis, and biological evaluation of novel substituted purines as HIV-1 Tat-TAR inhibitors

A series of novel substituted purines containing a side chain with a terminal amino or guanidyl group were designed and synthesized as HIV-1 Tat-TAR inhibitors. All the compounds could effectively block the TAR transactivation in human 293T cells with the CAT expression percentage ranging from 34.4% to 65.7% and showed high antiviral effects with low cytotoxicities in inhibiting the formation of SIV-induced syncytium in CEM174 cells. Molecular modeling studies by Auto-dock process suggest that the compounds bind to TAR RNA in two different modes.     

Design, synthesis and biological evaluation of 3-substituted 2,5-dimethyl-N-(3-(1H-tetrazol-5-yl)phenyl)pyrroles as novel potential HIV-1 gp41 inhibitors

Based on the structure of HIV-1 gp41 binding site for small-molecule inhibitors, optimization of lead 2 resulted in the discovery of a new series of 2,5-dimethyl-3-(5-(N-phenylrhodaninyl)methylene)-N-(3-(1H-tetrazol-5-yl)phenyl)pyrrole compounds with improved anti-HIV-1 activity. The most active compounds 13a and 13j exhibited significant potency against gp41 6-HB formation with IC(50) values of 4.4 and 4.6 μM and against HIV-1 replication in the MT-2 cells with EC(50) values of 3.2 and 2.2 μM, respectively, thus providing a new starting point to develop highly potent small-molecule HIV fusion inhibitors targeting gp41.     

Design,synthesis and biological evaluation of 3-hydroxyquinazoline-2,4(1H,3H)-diones as dual inhibitors of HIV-1 reverse transcriptase-associated RNase H and integrase

A novel series of 3-hydroxyquinazoline-2,4(1H,3H)-diones derivatives has been designed and synthesized. Their biochemical characterization revealed that most of the compounds were effective inhibitors of HIV-1 RNase H activity at sub to low micromolar concentrations. Among them, II-4 was the most potent in enzymatic assays, showing an IC₅₀ value of 0.41 ± 0.13 μM, almost five times lower than the IC₅₀ obtained with β-thujaplicinol. In addition, II-4 was also effective in inhibiting HIV-1 IN strand transfer activity (IC₅₀ = 0.85 ± 0.18 μM) but less potent than raltegravir (IC₅₀ = 71 ± 14 nM). Despite its relatively low cytotoxicity, the efficiency of II-4 in cell culture was limited by its poor membrane permeability. Nevertheless, structure-activity relationships and molecular modeling studies confirmed the importance of tested 3-hydroxyquinazoline-2,4(1H,3H)-diones as useful leads for further optimization.     

Design,synthesis and biological evaluation of novel aryl-acrylic derivatives as novel indoleamine-2,3-dioxygenase 1 (IDO1) inhibitors

Two series of novel aryl-acrylic derivatives were designed, synthesized, and screened in enzymatic and cellular inhibitory activities. All compounds showed moderate to significant potency. The SAR analyses indicated that the semicarbazone linker is better than the 1,2,3-triazole linker. Among semicarbazone compounds that R₁ bearing di-chain amino groups exhibited superior activities to those with morpholino group. Furthermore, compounds with electron-withdrawing groups at the 2-position or 4-position on the terminal phenyl ring were more active. Among these, compounds 7g, 7i, 7m and 7n exhibited the inhibitory potency in the low micromolar range and displayed negligible level of cytotoxicity against normal HeLa cells. In addition, the study suggested that the aryl-acrylic is an interesting novel scaffold for IDO1 inhibition for further development.     

Design,synthesis and biological evaluation of novel triaryl (Z)-olefins as tamoxifen analogues

Tamoxifen (TAM) is used for the treatment and prevention of estrogen receptor positive breast cancer. However, the limited activity, toxicity and the development of resistance raised the current need for new potent nontoxic antiestrogen. Six novel TAM analogues 5a–f were synthesized using McMurry olefination reaction. Replacement of the dimethylamino group in TAM by piperidino, piperazino or N-methyl piperazino, substituting the phenyl ring with florine atom at p-position and changing the ethyl group by methyl, afforded compounds showing comparable activity to TAM (1). Compounds 5c and 5e showed significant increase in antiproliferative activity in two breast cancer cell lines (MCF-7 and MDA-MB-231) compared to tamoxifen, while other compounds showed similar activity. The increased anticancer activity of compounds 5c and 5e was attributed to their ability to induce ER-independent cell death.