Identification of novel diarylpyrimidine derivatives as potent HIV-1 non-nucleoside reverse transcriptase inhibitors against wild-type and K103N mutant viruses.

HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) play a crucial role in combination antiretroviral therapy (cART). To further enhance their antiviral activity and anti-resistance properties, we developed a series of novel NNRTIs, by specifically targeting tolerant region I of the NNRTI binding pocket. Among them, compound 9t-2 displayed excellent anti-HIV-1 potency against wild-type and prevalent mutant strains with EC50 values between 0.0019 and 0.012 µM. This outperformed the positive drugs ETR, NVP and RPV. Aslo, ELISA results confirmed that these compounds can effectively inhibit the activity of HIV-1 RT. Molecular dynamics (MD) simulation studies indicated that the thiomorpholine-1,1-dioxide moiety of 9t-2 is capable of establishing additional interactions with residues P225, F227 and P236 in the tolerant region I, which contributed to its enhanced activity. Compound 9t-2 possessed negligible inhibitory effect on the five main CYP isoenzymes (IC50 > 10 µM), indicating a low potential for inducing CYP-mediated drug-drug interactions. In conclusion, compound 9t-2, with its enhanced anti-resistance properties, stands out as a promising lead compound for further optimization towards discovering the new generation of anti-HIV agents.

Discovery of novel diarypyrimidine derivatives bearing six-membered non-aromatic heterocycles as potent HIV-1 NNRTIs with improved anti-resistance and drug-like profiles.

Taking our previously reported HIV-1 NNRTIs BH-11c and XJ-10c as lead compounds, series of novel diarypyrimidine derivatives bearing six-membered non-aromatic heterocycles were designed to improve anti-resistance and drug-like profiles. According to the three rounds of in vitro antiviral activity screening, compound 12g was the most active inhibitor against wild-type and five prevalent NNRTI-resistant HIV-1 strains with EC50 values ranging from 0.024 to 0.0010 µM. This is obviously better than the lead compound BH-11c and the approved drug ETR. Detailed structure-activity relationship was investigated to provide valuable guidance for further optimization. The MD simulation study indicated that 12g could form additional interactions with residues around the binding site in HIV-1 RT, which provided reasonable explanations for its improved anti-resistance profile compared to ETR. Furthermore, 12g showed significant improvement in water solubility and other drug-like properties compared to ETR. The CYP enzymatic inhibitory assay indicated that 12g was unlikely to induce CYP-mediated drug-drug interactions. 12g pharmacokinetics parameters were investigated and it displayed a long half-life of 6.59 h in vivo. The properties of compound 12g make it a promising lead compound for the development of new generation of antiretroviral drugs.

Discovery of diarylpyrimidine derivatives bearing piperazine sulfonyl as potent HIV-1 nonnucleoside reverse transcriptase inhibitors.

HIV-1 reverse transcriptase is one of the most attractive targets for the treatment of AIDS. However, the rapid emergence of drug-resistant strains and unsatisfactory drug-like properties seriously limit the clinical application of HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs). Here we show that a series of piperazine sulfonyl-bearing diarylpyrimidine-based NNRTIs were designed to improve the potency against wild-type and NNRTI-resistant strains by enhancing backbone-binding interactions. Among them, compound 18b1 demonstrates single-digit nanomolar potency against the wild-type and five mutant HIV-1 strains, which is significantly better than the approved drug etravirine. The co-crystal structure analysis and molecular dynamics simulation studies were conducted to explain the broad-spectrum inhibitory activity of 18b1 against reverse transcriptase variants. Besides, compound 18b1 demonstrates improved water solubility, cytochrome P450 liability, and other pharmacokinetic properties compared to the currently approved diarylpyrimidine (DAPY) NNRTIs. Therefore, we consider compound 18b1 a potential lead compound worthy of further study.

Discovery and Mechanistic Investigation of Piperazinone Phenylalanine Derivatives with Terminal Indole or Benzene Ring as Novel HIV-1 Capsid Modulators.

HIV-1 capsid (CA) performs multiple roles in the viral life cycle and is a promising target for antiviral development. In this work, we describe the design, synthesis, assessment of antiviral activity, and mechanistic investigation of 20 piperazinone phenylalanine derivatives with a terminal indole or benzene ring. Among them, F2-7f exhibited moderate anti-HIV-1 activity with an EC50 value of 5.89 µM, which was slightly weaker than the lead compound PF74 (EC50 = 0.75 µM). Interestingly, several compounds showed a preference for HIV-2 inhibitory activity, represented by 7f with an HIV-2 EC50 value of 4.52 µM and nearly 5-fold increased potency over anti-HIV-1 (EC50 = 21.81 µM), equivalent to PF74 (EC50 = 4.16 µM). Furthermore, F2-7f preferred to bind to the CA hexamer rather than to the monomer, similar to PF74, according to surface plasmon resonance results. Molecular dynamics simulation indicated that F2-7f and PF74 bound at the same site. Additionally, we computationally analyzed the ADMET properties for 7f and F2-7f. Based on this analysis, 7f and F2-7f were predicted to have improved drug-like properties and metabolic stability over PF74, and no toxicities were predicted based on the chemotype of 7f and F2-7f. Finally, the experimental metabolic stability results of F2-7f in human liver microsomes and human plasma moderately correlated with our computational prediction. Our findings show that F2-7f is a promising small molecule targeting the HIV-1 CA protein with considerable development potential.

The current progress in the use of boron as a platform for novel antiviral drug design.

INTRODUCTION: Boron has attracted extensive interest due to several FDA-approved boron-containing drugs and other pharmacological agents in clinical trials. As a semimetal, it has peculiar biochemical characteristics which could be utilized in designing novel drugs against drug-resistant viruses. Emerging and reemerging viral pandemics are major threats to human health. Accordingly, we aim to comprehensively review the current status of antiviral boron-containing compounds. AREAS COVERED: This review focuses on the utilization of boron to design molecules against viruses from two perspectives: (i) single boron atom-containing compounds acting on miscellaneous viral targets and (ii) boron clusters. The peculiar properties of antiviral boron-containing compounds and their diverse binding modes with viral targets are described in detail in this review. EXPERT OPINION: Compounds bearing boronic acid can interact with viral targets by forming covalent or robust hydrogen bonds. This feature is valuable for combating resistant viruses. Furthermore, boron clusters can form dihydrogen bonds and bear features such as three-dimensional aromaticity, hydrophobicity, and biological stability. All these features demonstrated boron as a probable essential element with immense potential for drug design.

Perception, knowledge and attitude towards influenza vaccine during COVID-19 pandemic in Jordanian population.

INTRODUCTION: Seasonal influenza is considered as one of the major causes of morbidity and mortality worldwide. This needs solutions to decrease burdens on the healthcare systems especially during the Coronavirus Disease (COVID-19) pandemic. Population knowledge, perception and attitude towards influenza vaccine during COVID-19 pandemic could have a positive impact to decrease mortality, morbidity and burdens on the healthcare system. This study focuses on investigating knowledge, attitude and practice (KAP) of Jordanian adults towards influenza vaccine during COVID-19 pandemic. METHODS: This cross-sectional study recruited 1112 randomly selected Jordanian adults. A four-part questionnaire was designed and included questions about the demographic and clinical characteristics, perception about influenza, attitudes towards the role of influenza vaccine during COVID-19 pandemic and the factors that affect respondents' practice towards influenza vaccine. RESULTS: 73.1% population were not vaccinated, and most were not willing to be vaccinated during the COVID-19 pandemic. 55% of the population thought that influenza vaccine decreased the burden on the Jordanian healthcare system. The major refusal factor to be vaccinated was because influenza was not considered as a threat (41.3%). People mostly got their information about influenza vaccine from social media (64.3%). The role of the pharmacist and physician was neglected. CONCLUSIONS: The reinforcement of the role of pharmacists, physician and media to educate people about the importance of influenza vaccine during the COVID-19 pandemic is needed. Furthermore, campaigns should be conducted to increase the population awareness towards the importance of influenza vaccine uptake and its importance.

Design, synthesis, and mechanistic investigations of phenylalanine derivatives containing a benzothiazole moiety as HIV-1 capsid inhibitors with improved metabolic stability.

Further clinical development of PF74, a lead compound targeting HIV-1 capsid, is impeded by low antiviral activity and inferior metabolic stability. By modifying the benzene (region I) and indole of PF74, we identified two potent compounds (7m and 7u) with significantly improved metabolic stability. Compared to PF74, 7u displayed greater metabolic stability in human liver microsomes (HLMs) with half-life (t1/2) 109-fold that of PF74. Moreover, mechanism of action (MOA) studies demonstrated that 7m and 7u effectively mirrored the MOA of compounds that interact within the PF74 interprotomer pocket, showing direct and robust interactions with recombinant CA, and 7u displaying antiviral effects in both the early and late stages of HIV-1 replication. Furthermore, MD simulation corroborated that 7u was bound to the PF74 binding site, and the results of the online molinspiration software predicted that 7m and 7u had desirable physicochemical properties. Unexpectedly, this series of compounds exhibited better antiviral activity than PF74 against HIV-2, represented by compound 7m whose anti-HIV-2 activity was almost 5 times increased potency over PF74. Therefore, we have rationally redesigned the PF74 chemotype to inhibitors with novel structures and enhanced metabolic stability in this study. We hope that these new compounds can serve as a blueprint for developing a new generation of HIV treatment regimens.

Design, synthesis, and antiviral evaluation of novel piperidine-substituted arylpyrimidines as HIV-1 NNRTIs by exploring the hydrophobic channel of NNIBP.

Herein, alkenylpiperidine and alkynylpiperidine moieties were introduced into the left wing of DAPYs (diarylpyrimidines) to explore the new site of the NNIBP (non-nucleoside inhibitor binding pocket) protein-solvent interface region via the structure-based drug design strategy. All the synthesized compounds displayed nanomolar to submicromolar activity against WT (wild-type) HIV-1. Among all, compound FT1 (EC50 = 19 nM) was found to be the most active molecule, which is better than NVP (EC50 = 0.10 µM). In addition, most of the compounds displayed micromolar activity against K103N and E138K mutant strains, while FT1 (EC50(K103N) = 50 nM, EC50(E138K) = 0.19 µM) still has the most effective activity. The molecular dynamics simulation studies revealed that the presence of pyridine moiety of FT1 was essential and played a significant role in its binding with RT (reverse transcriptase).

Design, synthesis, and mechanism study of dimerized phenylalanine derivatives as novel HIV-1 capsid inhibitors.

HIV-1 capsid (CA) plays indispensable and multiple roles in the life cycle of HIV-1, become an attractive target in antiviral therapy. Herein, we report the design, synthesis, and mechanism study of a novel series of dimerized phenylalanine derivatives as HIV-1 capsid inhibitors using 2-piperazineone or 2,5-piperazinedione as a linker. The structure-activity relationship (SAR) indicated that dimerized phenylalanines were more potent than monomers of the same chemotype. Further, the inclusion of fluorine substituted phenylalanine and methoxyl substituted aniline was found to be beneficial for antiviral activity. From the synthesized series, Q-c4 was found to be the most potent compound with an EC50 value of 0.57 µM, comparable to PF74. Interestingly, Q-c4 demonstrated a slightly higher affinity to the CA monomer than the CA hexamer, commensurate with its more significant effect in the late-stage of the HIV-1 lifecycle. Competitive SPR experiments with peptides from CPSF6 and NUP153 revealed that Q-c4 binds to the interprotomer pocket of hexameric CA as designed. Single-round infection assays showed that Q-c4 interferes with the HIV-1 life cycle in a dual-stage manner, affecting both pre-and post-integration. Stability assays in human plasma and human liver microsomes indicated that although Q-c4 has improved stability over PF74, this kind of inhibitor still requires further optimization. And the results of the online molinspiration software predicted that Q-c4 has desirable physicochemical properties but some properties still have some violation from the Lipinski rule of five. Overall, the dimerized phenylalanines are promising novel platforms for developing future HIV-1 CA inhibitors with considerable potential for optimization.

Discovery of Novel Dihydrothiopyrano[4,3-d]pyrimidine Derivatives as Potent HIV-1 NNRTIs with Significantly Reduced hERG Inhibitory Activity and Improved Resistance Profiles.

Enlightened by the available structural biology information, a novel series of dihydrothiopyrano[4,3-d]pyrimidine derivatives were rationally designed via scaffold hopping and molecular hybridization strategies. Notably, compound 20a yielded exceptionally potent antiviral activities (EC50 = 4.44-54.5 nM) against various HIV-1 strains and improved resistance profiles (RF = 0.5-5.6) compared to etravirine and rilpivirine. Meanwhile, 20a exhibited reduced cytotoxicity (CC50 = 284 µM) and higher SI values (SI = 5210-63992). Molecular dynamics simulations were performed to rationalize the distinct resistance profiles. Besides, 20a displayed better solubility (sol. = 12.8 µg/mL) and no significant inhibition of the main CYP enzymes. Furthermore, 20a was characterized for prominent metabolic stability and in vivo safety properties. Most importantly, the hERG inhibition profile of 20a (IC50 = 19.84 µM) was a remarkable improvement. Overall, 20a possesses huge potential to serve as a promising drug candidate due to its excellent potency, low toxicity, and favorable drug-like properties.

Comparative QM/MM Molecular Dynamics and Umbrella Sampling Simulations: Interaction of the Zinc-Bound Intermediate Gem-Diolate Trapoxin A Inhibitor and Acetyl-l-lysine Substrate with Histone Deacetylase 8.

Targeting the genetic material without destruction is a priority to develop safe anticancer drugs. Histone deacetylase 8 (HDAC8), which is proved to be involved in carcinogenesis, is an enzyme associated with the chromatin for post-translational deacetylation of acetylated lysine. In this study, HDAC8 co-crystallized with the intermediate state tetrapeptide Trapoxin A (TA) inhibitor and the holoenzyme are utilized to find their conformational ensembles. Furthermore, the co-crystallized intermediate gem-diolate TA was used to find optimum interactions with the active site residues by conventional molecular dynamics (MD) simulation and QM/MM umbrella sampling. Finally, the intermediate state of the acetyl-l-lysine substrate was explored by QM/MM steered MD and compared to the binding of the intermediate state of the inhibitor. This research showed that HDAC8 is flexible and exists in conformational ensembles in its holoenzyme state. Binding of the intermediate state TA stabilizes its conformation. The optimum binding to the active site of HDAC8 for structures of gem-diolate TA (intermediate state) and acetyl-l-lysine (intermediate state) was determined according to the corresponding energy profiles. The use of these models will aid in the design of potentially reversible, potent, and selective inhibitors of HDAC8 for cancer treatment.

RNA knockdown by synthetic peptidyl-oligonucleotide ribonucleases: behavior of recognition and cleavage elements under physiological conditions.

Sequence-specific protein-based ribonucleases are not found in nature. Absolute sequence selectivity in RNA cleavage in vivo normally requires multi-component complexes that recruit a guide RNA or DNA for target recognition and a protein-RNA assembly for catalytic functioning (e.g. RNAi molecular machinery, RNase H). Recently discovered peptidyl-oligonucleotide synthetic ribonucleases selectively knock down pathogenic RNAs by irreversible cleavage to offer unprecedented opportunities for control of disease-relevant RNA. Understanding how to increase their potency, selectivity and catalytic turnover will open the translational pathway to successful therapeutics. Yet, very little is known about how these chemical ribonucleases bind, cleave and leave their target. Rational design awaits this understanding in order to control therapy, particularly how to overcome the trade-off between sequence specificity and potency through catalytic turnover. We illuminate this here by characterizing the interactions of these chemical RNases with both complementary and non-complementary RNAs using Tm profiles, fluorescence, UV-visible and NMR spectroscopies. Crucially, the level of counter cations, which are tightly-controlled within cellular compartments, also controlled these interactions. The oligonucleotide component dominated interaction between conjugates and complementary targets in the presence of physiological levels of counter cations (K+), sufficient to prevent repulsion between the complementary nucleic acid strands to allow Watson-Crick hydrogen bonding. In contrast, the positively-charged catalytic peptide interacted poorly with target RNA, when counter cations similarly screened the negatively-charged sugar-phosphate RNA backbones. The peptide only became the key player, when counter cations were insufficient for charge screening; moreover, only under such non-physiological conditions did conjugates form strong complexes with non-complementary RNAs.Communicated by Ramaswamy H. Sarma.

Discovery and optimizing polycyclic pyridone compounds as anti-HBV agents.

INTRODUCTION: Hepatitis B disease is caused by the hepatitis B virus (HBV), which is a DNA virus that belongs to the Hepadnaviridae family. It is a considerable health burden, with 257 million active cases globally. Long-standing infection may create a fundamental cause of liver disease and chronic infections, including cirrhosis, hepatocellular, and carcinoma liver failure. There is an urgent need to develop novel, safe, and effective drug candidates with a novel mechanism of action, improved activity, efficacy, and cure rate. AREAS COVERED: Herein, the authors provide a concise report focusing on a general and cutting-edge overview of the current state of polycyclic pyridone-related anti-HBV agent patents from 2016 to 2018 and some future perspectives. EXPERT OPINION: In medicinal chemistry, high-throughput screening (HTS), hit-to-lead optimization (H2L), bioisosteric replacement, and scaffold hopping approaches are playing a major role in the discovery and development of HBV inhibitors. Developing polycyclic pyridone-related anti-HBV agents that could target host factors has attracted significant interest and attention in recent years.

Design, Synthesis, and Mechanism Study of Benzenesulfonamide-Containing Phenylalanine Derivatives as Novel HIV-1 Capsid Inhibitors with Improved Antiviral Activities.

The HIV-1 CA protein has gained remarkable attention as a promising therapeutic target for the development of new antivirals, due to its pivotal roles in HIV-1 replication (structural and regulatory). Herein, we report the design and synthesis of three series of benzenesulfonamide-containing phenylalanine derivatives obtained by further structural modifications of PF-74 to aid in the discovery of more potent and drug-like HIV-1 CA inhibitors. Structure-activity relationship studies of these compounds led to the identification of new phenylalanine derivatives with a piperazinone moiety, represented by compound 11l, which exhibited anti-HIV-1NL4-3 activity 5.78-fold better than PF-74. Interestingly, 11l also showed anti-HIV-2ROD activity (EC50 = 31 nM), with almost 120 times increased potency over PF-74. However, due to the higher significance of HIV-1 as compared to HIV-2 for the human population, this manuscript focuses on the mechanism of action of our compounds in the context of HIV-1. SPR studies on representative compounds confirmed CA as the binding target. The action stage determination assay demonstrated that these inhibitors exhibited antiviral activities with a dual-stage inhibition profile. The early-stage inhibitory activity of compound 11l was 6.25 times more potent as compared to PF-74 but appeared to work via the accelerating capsid core assembly rather than stabilization. However, the mechanism by which they exert their antiviral activity in the late stage appears to be the same as PF-74 with less infectious HIV-1 virions produced in their presence, as judged p24 content studies. MD simulations provided the key rationale for the promising antiviral potency of 11l. Additionally, 11l exhibited a modest increase in HLM and human plasma metabolic stabilities as compared to PF-74, as well as a moderately improved pharmacokinetic profile, favorable oral bioavailability, and no acute toxicity. These studies provide insights and serve as a starting point for subsequent medicinal chemistry efforts in optimizing these promising HIV inhibitors.

Design, synthesis and structure-activity relationships of 4-phenyl-1H-1,2,3-triazole phenylalanine derivatives as novel HIV-1 capsid inhibitors with promising antiviral activities.

HIV-1 CA is involved in different stages of the viral replication cycle, performing essential roles in both early (uncoating, reverse transcription, nuclear import, integration) and late events (assembly). Recent efforts have demonstrated HIV-1 CA protein as a prospective therapeutic target for the development of new antivirals. The most extensively studied CA inhibitor, PF-3450074 (PF-74, discovered by Pfizer), that targets an inter-protomer pocket within the CA hexamer. Herein we reported the design, synthesis, and biological evaluation of a series of 4-phenyl-1H-1,2,3-triazole phenylalanine derivatives as HIV-1 CA inhibitors based on PF-74 scaffold. Most of the analogues demonstrated potent antiviral activities, among them, the anti-HIV-1 activity of 6a-9 (EC50 = 3.13 µM) is particularly prominent. The SPR binding assay of selected compounds (6a-9, 6a-10, 5b) suggested direct and effective interaction with recombinant CA proteins. The mechanism of action studies also demonstrated that 6a-9 displays the effects in both the early and late stages of HIV-1 replication. To explore the potential binding mode of the here presented analogues, 6a-9 was analyzed by MD simulation to predict its binding to the active site of HIV-1 CA monomer. In conclusion, this novel series of antivirals can serve as a starting point for the development of a new generation of HIV-1 treatment regimen and highlights the potentiality of CA as a therapeutic target.

Discovery of novel "Dual-site" binding oseltamivir derivatives as potent influenza virus neuraminidase inhibitors.

From our research group, it was noticed that oseltamivir derivatives targeting 150-cavity of neuraminidase enzyme (NA) could significantly increase antiviral activity. Thus, we further enriched the C5-NH2 position of oseltamivir structure to obtain more potent oseltamivir derivatives. In this article a series of oseltamivir derivatives were synthesized by modifying C5-NH2 position of oseltamivir. All the compounds were evaluated for in vitro antiviral activity against H5N1 and H5N8. Encouragingly, compounds 9a and 11e were exhibited prominent activity, which is similar to oseltamivir carboxylate (OSC) and in NAs inhibitory assay, 11e showed remarkable potency against N1 (H5N1), N2 (H5N2), N6 (H5N6) and N8 (H5N8). In addition, 11e demonstrated low cytotoxicity and no obvious toxicity at the dose of 1500 mg/kg in mice. Molecular docking studies of 9a and 11e provided a plausible rationale for the high potency against group-1 NAs. This work provided new insights to design further neuraminidase inhibitors, which can help to investigate new potent inhibitors for group-1 and group-2 shortly.

Novel urate transporter 1 (URAT1) inhibitors: a review of recent patent literature (2016-2019).

Introduction: Human urate transporter 1 (URAT1), which is an influx transporter protein, is located at the apical surface of renal tubular cells and presumed to be the major transporter responsible for the reabsorption of urate from blood. About 90% of patients develop hyperuricemia due to insufficient urate excretion; thus, it is important to develop URAT1 inhibitors that could enhance renal urate excretion by blocking the reabsorption of urate anion. Areas covered: In this review, the authors addressed the patent applications (2016-2019) about URAT1 inhibitors and some medicinal chemistry strategies employed in these patents. Expert opinion: Substituent decorating, bioisosterism, and scaffold hopping are three common medicinal chemistry strategies used in the discovery of URAT1 inhibitors. Meanwhile, the introduction of sulfonyl group into small molecules has become one of the important strategies for structural optimization of URAT1 inhibitors. Furthermore, developing drug candidates targeting both URAT1 and xanthine oxidase (XOD) has attracted lots of interest and attention.

The effect of ferrous ions, calcium ions and citric acid on absorption of ciprofloxacin across caco-2 cells: practical and structural approach.

OBJECTIVE: To study the potential influence of selected metal ions on absorption (and hence oral bioavailability of ciprofloxacin (Cipro) in presence and absence of a competing ligand. SIGNIFICANCE: The presence of metal ions together with Cipro results in complexes exhibiting a decreased bioavailability. Attempts were made to better understand the mechanism of decreased Cipro bioavailability in the presence of metals such as calcium and ferrous ions, and a small-sized ligand citric acid (CitA). METHODS: Effect of complex size or other potential factors was studied using diffusion through synthetic membrane, permeation studies across Caco-2 cells and capillary electrophoresis. A molecular dynamics (MD) simulation study was conducted to find the arrangement and the nature of the interactions between Cipro molecules and ferrous ions. RESULTS: Cipro was shown to form complexes with metals and CitA. The presence of CitA improved permeation of Cipro through the synthetic membrane but this was not as obvious in case of Caco-2 cells. Capillary electrophoresis suggested the existence of large molecular aggregates of Cipro: metal complexes. MD simulations offered clear evidence of large size aggregates in line with the experimental findings. CitA alone significantly improved permeation of Cipro through Caco-2 cells. CONCLUSIONS: The size of the formed complexes, rather than the decrease in the solubility of formed complexes, plays a significant role in permeation (absorption) of Cipro. CitA might ameliorate the effect of co-administered metal ions on the bioavailability of Cipro.

Discovery of novel 1,4-disubstituted 1,2,3-triazole phenylalanine derivatives as HIV-1 capsid inhibitors.

The HIV-1 capsid (CA) protein plays crucial roles in both early and late stages of the viral life cycle, which has intrigued researchers to target it to develop anti-HIV drugs. Accordingly, in this research, we report the design, synthesis and biological evaluation of a series of novel phenylalanine derivatives as HIV-1 CA protein inhibitors using the Cu(I)-catalyzed azide and alkyne 1,3-dipolar cycloaddition (CuAAC) reaction. Among this series of inhibitors, compound II-10c displayed a remarkable anti-HIV activity (EC50 = 2.13 µM, CC50 > 35.49 µM). Furthermore, surface plasmon resonance (SPR) binding assays showed that compounds II-10c and PF-74 (lead compound) have similar affinities to HIV-1 CA monomer. Further investigation showed that the weak permeability and water solubility of representative compounds were probably the important factors that restricted their cell-based activity. Preliminary structure-activity relationships (SARs) were inferred based on the activities of these compounds, and their known structure. The most promising new compound was studied with molecular dynamics simulation (MD) to determine the preferred interactions with the drug target. Finally, the activities of members of this series of inhibitors were deeply inspected to find the potential reasons for their anti-HIV-1 activity from various perspectives. This highlights the important factors required to design compounds with improved potency.

Discovery of phenylalanine derivatives as potent HIV-1 capsid inhibitors from click chemistry-based compound library.

The HIV-1 capsid (CA) protein plays essential roles in both early and late stages of HIV-1 replication and is considered an important, clinically unexploited therapeutic target. As such, small drug-like molecules that inhibit this critical HIV-1 protein have become a priority for several groups. Therefore, in this study we explore small molecule targeting of the CA protein, and in particular a very attractive inter-protomer pocket. We report the design, parallel synthesis, and anti-HIV-1 activity evaluation of a series of novel phenylalanine derivatives as HIV-1 CA protein inhibitors synthesized via Cu(I)-catalyzed alkyne-azide 1,3-dipolar cycloaddition (CuAAC) reaction. We demonstrate robust inhibitory activity over a range of potencies against the HIV-1 NL4-3 reference strain. In particular, compound 13m exhibited the greatest potency and lowest toxicity within this new series with an EC50 value of 4.33 µM and CC50 value of >57.74 µM (SI > 13.33). These values are very similar to the lead compound PF-74 (EC50 = 5.95 µM, CC50 > 70.50 µM, SI > 11.85) in our assay, despite significant structural difference. Furthermore, we demonstrate via surface plasmon resonance (SPR) binding assays that 13m interacts robustly with recombinant HIV-1 CA and exhibits antiviral activity in both the early and late stages of HIV-1 replication. Overall, the novel parallel synthesis and structure-activity relationships (SARs) identified within this study set the foundation for further rational optimization and discovery of CA-targeting compounds with improved potency.