Discovery, optimization, and target identification of novel coumarin derivatives as HIV-1 reverse transcriptase-associated ribonuclease H inhibitors

Despite significant advances in antiretroviral therapy, acquired immunodeficiency syndrome remains as one of the leading causes of death worldwide. New antiretroviral drugs combined with updated treatment strategies are needed to improve convenience, tolerability, safety, and antiviral efficacy of available therapies. In this work, a focused library of coumarin derivatives was exploited by cell phenotypic screening to discover novel inhibitors of HIV-1 replication. Five compounds (DW-3, DW-4, DW-11, DW-25 and DW-31) showed moderate activity against wild-type and drug-resistant strains of HIV-1 (IIIB and RES056). Four of those molecules were identified as inhibitors of the viral RT-associated RNase H. Structural modification of the most potent DW-3 and DW-4 led to the discovery of compound 8a. This molecule showed increased potency against wild-type HIV-1 strain (EC = 3.94 ± 0.22 μM) and retained activity against a panel of mutant strains, showing EC values ranging from 5.62 μM to 202 μM. In enzymatic assays, 8a was found to inhibit the viral RNase H with an IC of 12.3 μM. Molecular docking studies revealed that 8a could adopt a binding mode similar to that previously reported for other active site HIV-1 RNase H inhibitors.Natural Science Foundation of China (NSFC Nos. 81973181, 81903453), Shandong Provincial Key research and development project (Nos. 2019JZZY021011), Shandong Provincial Natural Science Foundation (ZR2019BH011, ZR2020YQ61, ZR2020JQ31), Foreign cultural and educational experts Project (GXL20200015001), Qilu Young Scholars Program of Shandong University, the Taishan Scholar Program at Shandong Province, and KU Leuven (GOA 10/014). Work in Madrid was supported by the Spanish Ministry of Science and Innovation (grant PID2019-104176RB-I00/AEI/10.13039/501100011033), and an institutional grant of Fundación Ramón Areces (Madrid, Spain)

Development of a practical synthesis of etravirine via a microwave-promoted amination

Abstract Background Etravirine (ETV) was approved as the second generation drug for use in individuals infected with HIV-1 in 2008 by the U.S. FDA with its unique antiviral activity, high specificity, and low toxicity. However, there are some shortcomings of the existing synthetic routes, such as the long reaction time and poor yield. Results This article describes our efforts to develop an efficient, practical, microwave-promoted synthetic method for one key intermediate of ETV, which is capable of being operated on a scale-up synthesis level. Through this optimized synthetic procedure, the amination reaction time decreased from 12 h to 15 min and the overall yield improved from 30.4 to 38.5%. Conclusion Overall, we developed a practical synthesis of ETV via a microwave-promoted method, and the synthetic procedure could be amenable to scale-up, and production costs could be significantly lowered

Current medicinal chemistry strategies in the discovery of novel HIV-1 ribonuclease H inhibitors

During HIV-1 genome replication, the viral reverse transcriptase-associated ribonuclease H (RT-associated RNase H) activity hydrolyzes the RNA strand of RNA/DNA heteroduplex intermediates. As of today, HIV-1 RNase H inhibitors (RHIs) remain at an investigational level, although none of them reached clinical trials. Therefore, RNase H remains as an attractive target for drug design and development. In this paper, we review the current status of medicinal chemistry strategies aimed at the discovery of novel RHIs, while discussing problems encountered in their characterization and further development, thereby providing an update on recent progress in the field.We gratefully acknowledge financial support from the National Natural Science Foundation of China (NSFC Nos. 82173677, 81773574), and the Science Foundation for Outstanding Young Scholars of Shandong Province (ZR2020JQ31). This work was supported in part by the Ministry of Science and Innovation of Spain through grant PID2019-104176RB-I00/AEI/10.13039/501100011033 awarded to L.M.-A. N.L.-C. is supported by a contract (PEJ‐2020‐AI/BMD‐19429) of the Youth Guarantee programme of the European Union, with the participation of the Comunidad de Madrid (Consejería de Educación, Universidades, Ciencia y Portavocía). An institutional grant of the Fundación Ramón Areces to the CBMSO is also acknowledged.Peer reviewe

In situ click chemistry-based rapid discovery of novel HIV-1 NNRTIs by exploiting the hydrophobic channel and tolerant regions of NNIBP

HIV-1 RT has been considered as one of the most important targets for the development of anti-HIV-1 drugs for their well-solved three-dimensional structure and well-known mechanism of action. In this study, with HIV-1 RT as target, we used miniaturized parallel click chemistry synthesis via CuAAC reaction followed by in situ biological screening to discover novel potent HIV-1 NNRTIs. A 156 triazole-containing inhibitor library was assembled in microtiter plates and in millimolar scale. The enzyme inhibition screening results showed that 22 compounds exhibited improved inhibitory activity. Anti-HIV-1 activity results demonstrated that A3N19 effected the most potent activity against HIV-1 IIIB (EC50 = 3.28 nM) and mutant strain RES056 (EC50 = 481 nM). The molecular simulation analysis suggested that the hydrogen bonding interactions of A3N19 with the main chain of Lys101 and Lys104 was responsible for its potency. Overall, the results indicated the in situ click chemistry-based strategy was rational and might be amenable for the future discovery of more potent HIV-1 NNRTIs.status: publishe

Structure-Activity Relationship Exploration of NNIBP Tolerant Region I Leads to Potent HIV-1 NNRTIs

Previous efforts in our lab have led to the development of human immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse transcriptase inhibitor (NNRTI) thiophene[3,2-d]pyrimidine compound 1 (K-5a2) with promising activity against wild-type and mutant HIV-1 strains. In this work, a series of novel diarylpyrimidines derivatives carrying a structurally diverse motif at the right wing of the lead K-5a2 was designed and synthesized as potential anti-HIV-1 agents. The results demonstrated that 8a yielded exceptionally potent activity against HIV-1 wild-type (50% effective concentration (EC50) = 3.30 nM) and mutant strain RES056 (EC50 = 22.6 nM) in MT-4 cells; in the reverse transcriptase inhibitory assay, 8a (half maximal inhibitory concentration (IC50) = 0.028 μM) was remarkably superior to that of K-5a2 (IC50 = 0.300 μM) and comparable to that of etravirine (ETR; IC50 = 0.011 μM). Notably, 8a exhibited better druggability than that of K-5a2, including significantly reduced CYP enzymatic inhibitory activity (IC50 > 50 μM), lower human ether-à-go-go related gene (hERG) inhibition (IC50 > 30 μM), and improved metabolic stability (short half-life, T1/2 = 77.5 min) in vitro.doi: 10.1021/acsinfecdis.0c00327status: publishe

Exploring the hydrophobic channel of NNIBP leads to the discovery of novel piperidine-substituted thiophene[3,2-d]pyrimidine derivatives as potent HIV-1 NNRTIs

In this report, a series of novel piperidine-substituted thiophene[3,2-d]pyrimidine derivatives were designed to explore the hydrophobic channel of the non-nucleoside reverse transcriptase inhibitors binding pocket (NNIBP) by incorporating an aromatic moiety to the left wing of the lead K-5a2. The newly synthesized compounds were evaluated for anti-HIV potency in MT-4 cells and inhibitory activity to HIV-1 reverse transcriptase (RT). Most of the synthesized compounds exhibited broad-spectrum activity toward wild-type and a wide range of HIV-1 strains carrying single non-nucleoside reverse transcriptase inhibitors (NNRTI)-resistant mutations. Especially, compound 26 exhibited the most potent activity against wild-type and a panel of single mutations (L100I, K103N, Y181C, Y188L and E138K) with an EC50 ranging from 6.02 to 23.9 nmol/L, which were comparable to those of etravirine (ETR). Moreover, the RT inhibition activity, preliminary structure-activity relationship and molecular docking were also investigated. Furthermore, 26 exhibited favorable pharmacokinetics (PK) profiles and with a bioavailability of 33.8%. Taken together, the results could provide valuable insights for further optimization and compound 26 holds great promise as a potential drug candidate for the treatment of HIV-1 infection.status: publishe

Discovery and Characterization of Fluorine-Substituted Diarylpyrimidine Derivatives as Novel HIV-1 NNRTIs with Highly Improved Resistance Profiles and Low Activity for the hERG Ion Channel

Our previous efforts have led to the development of two potent NNRTIs, K-5a2 and 25a, exhibiting effective anti-HIV-1 potency and resistance profiles compared with etravirine. However, both inhibitors suffered from potent hERG inhibition and short half-life. In this article, with K-5a2 and etravirine as leads, series of novel fluorine-substituted diarylpyrimidine derivatives were designed via molecular hybridization and bioisosterism strategies. The results indicated 24b was the most active inhibitor, exhibiting broad-spectrum activity (EC50 = 3.60-21.5 nM) against resistant strains, significantly lower cytotoxicity (CC50= 155 μM), and reduced hERG inhibition (IC50 > 30 μM). Crystallographic studies confirmed the binding of 24b and the role of the fluorine atom, as well as optimal contacts of a nitrile group with the main-chain carbonyl group of H235. Furthermore, 24b showed longer half-life and favorable safety properties. All the results demonstrated that 24b has significant promise in circumventing drug resistance as an anti-HIV-1 candidate.status: publishe

Discovery of piperidine-substituted thiazolo[5,4-d] pyrimidine derivatives as potent and orally bioavailable HIV-1 non-nucleoside reverse transcriptase inhibitors

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Design, synthesis, and biological evaluation of novel double-winged galloyl derivatives as HIV-1 RNase H inhibitors

Human immunodeficiency virus (HIV) reverse transcriptase (RT)-associated ribonuclease H (RNase H) remains as the only enzyme encoded within the viral genome not clinically validated as an antiviral target. We have previously reported that the galloyl derivative II-25 had RNase H inhibitory activity in enzymatic assays but showed weak antiviral activity in phenotypic assays due its large polarity and poor membrane permeability. In this report, we report on a series of II-25 derivatives, obtained by addition of different hydrophobic moieties ("the wings") at the C-2 and C-3 positions of the piperazine ring that showed improved RNase H inhibitory activity. Six compounds showed strong inhibitory activity and were found to be more potent than β-thujaplicinol in enzymatic assays. The most potent compound was IA-6 and exhibited the best inhibitory activity (IC50 = 0.067 ± 0.02 μM). IA-6 was around 11 and 30 times more potent than II-25 and β-thujaplicinol, respectively. Molecular modeling studies predict a strong hydrophobic interaction between the furylmethylaminyl group of IA-6 and the side chain of His539, explaining the potent HIV-1 RNase H inhibition. Unfortunately, none of the derivatives showed significant antiviral activity in cell culture. It is worth emphasizing that most of the obtained compounds show low cytotoxicity (CC50 > 20 μM), which confirms the significance of identifying galloyl derivatives as valuable leads for further optimization.We gratefully acknowledge financial support from the National Natural Science Foundation of China (NSFC Nos. 82173677, 81773574), the Key Project of NSFC for International Cooperation (No. 81420108027), the Shandong Provincial Key Research and Development Project (No. 2019JZZY021011), and the Science Foundation for Outstanding Young Scholars of Shandong Province (ZR2020JQ31). This work was supported in part by the Ministry of Science and Innovation of Spain through grant PID2019-104176RB-I00/AEI/10.13039/501100011 033 awarded to L.M.-A. J.M.R. is a predoctoral fellow of the Spanish Ministry of Universities (Formación de Profesorado Universitario, FPU19/01653). An institutional grant of the Fundación Ramón Areces to the CBMSO is also acknowledged.Peer reviewe