Development and in Vitro Evaluation of a Microbicide Gel Formulation for a Novel Non-Nucleoside Reverse Transcriptase Inhibitor Belonging to the N-Dihydroalkyloxybenzyloxopyrimidines (N-DABOs) Family

Binuclear palladacycles with ionisable and non-ionisable tethers as anticancer agents

The search for novel anticancer agents to replace the current platinum-based treatments remains an ongoing process. Palladacycles have shown excellent promise as demonstrated by our previous work which yielded BTC2, a binuclear palladadycle with a non-ionisable polyethylene glycol (PEG) tether. Here, we explore the importance of the PEG-tether length on the anticancer activity of the binuclear palladacycles by comparing three analogous binuclear palladacycles, BTC2, BTC5 and BTC6, in the oestrogen receptor positive MCF7 and triple-negative MDA-MB-231 breast cancer cell lines. In addition, these are compared to another analogue with an ionisable morpholine tether, BTC7. Potent anticancer activity was revealed through cell viability studies (MTT assays) revealed that while BTC6 showed similar potent anticancer activity as BTC2, it was less toxic towards non-cancerous cell lines. Interestingly, BTC7 and BTCF were less potent than the PEGylated palladacycles but showed significantly improved selectivity towards the triple-negative breast cancer cells. Cell death analysis showed that BTC7 and BTCF significantly induced apoptosis in both the cancer cell lines while the PEGylated complexes induced both apoptosis and secondary necrosis. Furthermore, experimental and computational DNA binding studies indicated partial intercalation and groove binding as the modes of action for the PEGylated palladacycles. Similarly, experimental and computational BSA binding studies indicated and specific binding sites in BSA dependent on the nature of the tethers on the complexes.

One-pot synthesis of 4-pyrimidone-2-thioether through base/acid-mediated condensation of S-alkylisothiourea and β-ketoester

4-Pyrimidone-2-thioethers can be useful synthetic precursors to densely functionalized pyrimidines, commonly encountered in bioactive molecules. A convenient one-pot access to 4-pyrimidone-2-thioethers is reported herein, which utilizes a sequential base- and acid-mediated condensation of alkylisothioureas with β-ketoesters. Owing to mild reaction conditions, good to excellent functional group tolerance and yields are achieved. The utility of this approach is demonstrated by the synthesis of the crucial adagrasib intermediate on a 200 gram scale.

Medicinal chemistry perspectives on the development of piperazine-containing HIV-1 inhibitors

The Human immunodeficiency virus (HIV) is the causative agent of acquired immunodeficiency syndrome (AIDS), one of the most perilous diseases known to humankind. A 2023 estimate put the number of people living with HIV around 40 million worldwide, with the majority benefiting from various antiretroviral therapies. Consequently, the urgent need for the development of effective drugs to combat this virus cannot be overstated. In the realm of medicinal and organic chemistry, the synthesis and identification of novel compounds capable of inhibiting HIV enzymes at different stages of their life cycle are of paramount importance. Notably, the spotlight is on the progress made in enhancing the potency of HIV inhibitors through the use of piperazine-based compounds. Multiple studies have revealed that the incorporation of a piperazine moiety results in a noteworthy enhancement of anti-HIV activity. The piperazine ring assumes a pivotal role in shaping the pharmacophore responsible for inhibiting HIV-1 at critical stage, including attachment, reverse transcription, integration, and protease activity. This review also sheds light on the various opportunities that can be exploited to develop effective antiretroviral targets and eliminate latent HIV reservoirs. The advancement of highly potent analogues in HIV inhibitor research has been greatly facilitated by contemporary medicinal strategies, including molecular/fragment hybridization, structure-based drug design, and bioisosterism. These techniques have opened up new avenues for the development of compounds with enhanced efficacy in combating the virus.

Development of multi-targetable chalcone derivatives bearing N-aryl piperazine moiety for the treatment of Alzheimer's disease

The multi-target directed ligand (MTDL) discovery has been gaining immense attention in the development of therapeutics for Alzheimer's disease (AD). The strategy has been evolved as an auspicious approach suitable to combat the heterogeneity and the multifactorial nature of AD. Therefore, multi-targetable chalcone derivatives bearing N-aryl piperazine moiety were designed, synthesized, and evaluated for the treatment of AD. All the synthesized compounds were screened for thein vitro activityagainst acetylcholinesterase (AChE), butylcholinesterase (BuChE), β-secretase-1 (BACE-1), and inhibition of amyloid β (Aβ) aggregation. Amongst all the tested derivatives, compound 41bearing unsubstituted benzylpiperazine fragment and para-bromo substitution at the chalcone scaffold exhibited balanced inhibitory profile against the selected targets. Compound 41 elicited favourable permeation across the blood-brain barrier in the PAMPA assay. The molecular docking and dynamics simulation studies revealed the binding mode analysis and protein-ligand stability ofthe compound with AChE and BACE-1. Furthermore,itameliorated cognitive dysfunctions and signified memory improvement in thein-vivobehavioural studies (scopolamine-induced amnesia model). Theex vivobiochemical analysis of mice brain homogenates established the reduced AChE and increased ACh levels. The antioxidant activity of compound 41 was accessed with the determination of catalase (CAT) and malondialdehyde (MDA) levels. The findings suggested thatcompound 41, containing a privileged chalcone scaffold, can act as a lead molecule for developing AD therapeutics.

Targeting GLI1 and GLI2 with small molecule inhibitors to suppress GLI-dependent transcription and tumor growth

Aberrant activation of Hedgehog (HH) signaling in cancer is the result of genetic alterations of upstream pathway components (canonical) or other oncogenic mechanisms (noncanonical), that ultimately concur to activate the zinc-finger transcription factors GLI1 and GLI2. Therefore, inhibition of GLI activity is a good therapeutic option to suppress both canonical and noncanonical activation of the HH pathway. However, only a few GLI inhibitors are available, and none of them have the profile required for clinical development due to poor metabolic stability and aqueous solubility, and high hydrophobicity. Two promising quinoline inhibitors of GLI were selected by virtual screening and subjected to hit-to-lead optimization, thus leading to the identification of the 4-methoxy-8-hydroxyquinoline derivative JC19. This molecule impaired GLI1 and GLI2 activities in several cellular models interfering with the binding of GLI1 and GLI2 to DNA. JC19 suppressed cancer cell proliferation by enhancing apoptosis, inducing a strong anti-tumor response in several cancer cell lines in vitro. Specificity towards GLI1 and GLI2 was demonstrated by lower activity of JC19 in GLI1- or GLI2-depleted cancer cells. JC19 showed excellent metabolic stability and high passive permeability. Notably, JC19 inhibited GLI1-dependent melanoma xenograft growth in vivo, with no evidence of toxic effects in mice. These results highlight the potential of JC19 as a novel anti-cancer agent targeting GLI1 and GLI2.

Development of novel S-N3-DABO derivatives as potent non-nucleoside reverse transcriptase inhibitors with improved potency and selectivity

Following on our initial discovery of S-CN-DABOs as non-nucleoside reverse transcriptase inhibitors (NNRTIs), a series of novel S-N₃-DABO derivatives F1-F31 were developed by substituting the cyano group of S-CN-DABOs with azide group. Some of these compounds were conferred significantly increased potency against wild-type HIV-1 and clinically observed mutant strains. Remarkably, the best compound F10 exerted a 7-fold improvement in potency (EC₅₀ = 0.053 μM) and 12.5-fold higher selectivity (SI = 6818) in MT-4 cells infected with wild-type HIV-1, compared to that of the parent compound B1 (EC₅₀ = 370 nM, SI = 547). The anti-HIV-1 activity of F10 against the tested mutant strains was prominently enhanced. For wild-type reverse transcriptase, it was approximately 19-fold more potent (IC₅₀ = 0.080 μM) than B1 (IC₅₀ = 1.51 μM). It was not found that this analog had significant inhibition of hERG, CYP, and acute toxicity after a single dose of F10 (1.0 g/kg).

Biological Evaluation and In Vitro Characterization of ADME Profile of In-House Pyrazolo[3,4-d]pyrimidines as Dual Tyrosine Kinase Inhibitors Active against Glioblastoma Multiforme

The therapeutic use of tyrosine kinase inhibitors (TKIs) represents one of the successful strategies for the treatment of glioblastoma (GBM). Pyrazolo[3,4-d]pyrimidines have already been reported as promising small molecules active as c-Src/Abl dual inhibitors. Herein, we present a series of pyrazolo[3,4-d]pyrimidine derivatives, selected from our in-house library, to identify a promising candidate active against GBM. The inhibitory activity against c-Src and Abl was investigated, and the antiproliferative profile against four GBM cell lines was studied. For the most active compounds endowed with antiproliferative efficacy in the low-micromolar range, the effects toward nontumoral, healthy cell lines (fibroblasts FIBRO 2-93 and keratinocytes HaCaT) was investigated. Lastly, the in silico and in vitro ADME properties of all compounds were also assessed. Among the tested compounds, the promising inhibitory activity against c-Src and Abl (K_i 3.14 µM and 0.44 µM, respectively), the irreversible, apoptotic-mediated death toward U-87, LN18, LN229, and DBTRG GBM cell lines (IC₅₀ 6.8 µM, 10.8 µM, 6.9 µM, and 8.5 µM, respectively), the significant reduction in GBM cell migration, the safe profile toward FIBRO 2-93 and HaCaT healthy cell lines (CC₅₀ 91.7 µM and 126.5 µM, respectively), the high metabolic stability, and the excellent passive permeability across gastrointestinal and blood-brain barriers led us to select compound 5 for further in vivo assays.

Privileged Scaffold Decoration for the Identification of the First Trisubstituted Triazine with Anti-SARS-CoV-2 Activity

Current therapy against severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) are based on the use of Remdesivir 1, Molnupiravir 2, and the recently identified Nirmatrelvir 3. Unfortunately, these three drugs showed some limitations regarding potency and possible drug-drug interactions. A series of derivatives coming from a decoration approach of the privileged scaffold s-triazines were synthesized and evaluated against SAR-CoV-2. One derivative emerged as the hit of the series for its micromolar antiviral activity and low cytotoxicity. Mode of action and pharmacokinetic in vitro preliminary studies further confirm the role as candidates for a future optimization campaign of the most active derivative identified with this work.

Proteins from Tenebrio molitor: An interesting functional ingredient and a source of ACE inhibitory peptides

The angiotensin-converting enzyme (ACE) inhibitory potential of the main protein fractions from Tenebrio molitor larvae (TML) was examined to evaluate their use as a novel antihypertensive functional food. Both fractions contained YAN tripeptide, previously reported as responsible for ACE inhibition. Although YAN has been synthesized and was used as a standard for LC-MS/MS quantification and IC₅₀ against ACE was determined, low yields of YAN from TML did not explain adequately the activity of the whole protein fraction. LC-HRMS/MS investigation led to the identification of other three peptides, which were evaluated in silico, synthesized and tested against ACE. Among them, tetrapeptide NIKY showed the most promising activity (52 µM), highlighting once more the potential of TML and paving the way for exploitation in novel foods.

Design, synthesis and biological evaluation of 2-pyrrolone derivatives as radioprotectors

It is known that p53 is an important transcription factor and plays a central role in ionizing radiation (IR)-induced DNA damage responses such as cell cycle arrest, DNA repair and apoptosis. We previously reported that regulating p53 protein is an effective strategy for modulating cell fate by reducing the acute side effects of radiation therapy. Herein, we report on the discovery of STK160830 as a new radioprotector from a chemical library at The University of Tokyo and the design, synthesis and biological evaluation of its derivatives. The radioprotective activity of STK160830 itself and its derivatives that were synthesized in this work was evaluated using a leukemia cell line, MOLT-4 cells as a model of normal cells that express the p53 protein in a structure-activity relationships (SAR) study. The experimental results suggest that a direct relationship exists between the inhibitory effect of these STK160830 derivatives on the expression level of p53 and their radioprotective activity and that the suppression of p53 by STK160830 derivatives contribute to protecting MOLT-4 cells from apoptosis that is induced by exposure to radiation.

DEAD-Box Helicase DDX3X as a Host Target against Emerging Viruses: New Insights for Medicinal Chemical Approaches

In recent years, globalization, global warming, and population aging have contributed to the spread of emerging viruses, such as coronaviruses (COVs), West Nile (WNV), Dengue (DENV), and Zika (ZIKV). The number of reported infections is increasing, and considering the high viral mutation rate, it is conceivable that it will increase significantly in the coming years. The risk caused by viruses is now more evident due to the COVID-19 pandemic, which highlighted the need to find new broad-spectrum antiviral agents able to tackle the present pandemic and future epidemics. DDX3X helicase is a host factor required for viral replication. Selective inhibitors have been identified and developed into broad-spectrum antivirals active against emerging pathogens, including SARS-CoV-2 and most importantly against drug-resistant strains. This perspective describes the inhibitors identified in the last years, highlighting their therapeutic potential as innovative broad-spectrum antivirals.

Multicomponent reactions in the synthesis of antiviral compounds

BACKGROUND

Multicomponent reactions are one-pot processes for the synthesis of highly functionalized hetero-cyclic and hetero-acyclic compounds, often endowed with biological activity.

OBJECTIVE

Multicomponent reactions are considered green processes with high atom economy. In addition, they present advantages compared to the classic synthetic methods such as high efficiency and low wastes production.

METHOD

In these reactions two or more reagents are combined together in the same flask to yield a product containing almost all the atoms of the starting materials.

RESULTS

The scope of this review is to present an overview of the application of multicomponent reactions in the synthesis of compounds endowed with antiviral activity. The syntheses are classified depending on the viral target.

CONCLUSION

Multicomponent reactions can be applied to all the stages of the drug discovery and development process making them very useful in the search for new agents active against emerging (viral) pathogens.

An SAMT-247 Microbicide Provides Potent Protection against Intravaginal Simian Immunodeficiency Virus Infection of Rhesus Macaques, whereas an Added Vaccine Component Elicits Mixed Outcomes

Because of microbicide noncompliance and lack of a durable, highly effective vaccine, a combined approach might improve HIV prophylaxis. We tested whether a vaccine-microbicide combination would enhance protection against SIV infection in rhesus macaques. Four macaque groups included vaccine only, vaccine-microbicide, microbicide only, and controls. Vaccine groups were primed twice mucosally with replicating adenovirus type 5 host range mutant SIV env/rev, gag, and nef recombinants and boosted twice i.m. with SIV gp120 proteins in alum. Controls and the microbicide-only group received adenovirus type 5 host range mutant empty vector and alum. The microbicide was SAMT-247, a 2-mercaptobenzamide thioester that targets the viral nucleocapsid protein NCp7, causing zinc ejection and preventing RNA encapsidation. Following vaccination, macaques were challenged intravaginally with repeated weekly low doses of SIV_mac251 administered 3 h after application of 0.8% SAMT-247 gel (vaccine-microbicide and microbicide groups) or placebo gel (vaccine-only and control groups). The microbicide-only group exhibited potent protection; 10 of 12 macaques remained uninfected following 15 SIV challenges. The vaccine-only group developed strong mucosal and systemic humoral and cellular immunity but did not exhibit delayed acquisition compared with adjuvant controls. However, the vaccine-microbicide group exhibited significant acquisition delay compared with both control and vaccine-only groups, indicating further exploration of the combination strategy is warranted. Impaired protection in the vaccine-microbicide group compared with the microbicide-only group was not attributed to a vaccine-induced increase in SIV target cells. Possible Ab-dependent enhancement will be further investigated. The potent protection provided by SAMT-247 encourages its movement into human clinical trials.

Recent Advances in the Design and Development of Non-nucleoside Reverse Transcriptase Inhibitor Scaffolds

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) have always been an important part of the anti-HIV-1 combination therapy known as combination antiretroviral therapy (cART) since 1996. The use of NNRTIs for about 22 years has led to some mutations in the residues that compose the reverse transcriptase active site, resulting in the emergence of drug-resistant viruses. Thus, the search for new potent NNRTIs with an improved safety profile and activity against drug-resistant HIV strains is indispensable, and many hit and lead NNRTIs have been discovered in the last decade. This review provides an overview of the development in this field from 2013 to August 2018.

CsF-Catalyzed Transannulation Reaction of Oxazolones: Diastereoselective Synthesis of Diversified trans- N-(6-Oxo-1,4,5,6-tetrahydropyrimidin-5-yl)benzamides with Arylidene Azlactones and Amidines

A versatile and straightforward synthetic strategy for the construction of new tetrasubstituted 1,3-diazinones is described. The procedure is based on CsF-catalyzed, microwave-assisted, ring transformation reaction of arylidene azlactones with amidines. Moreover, this technique provides diversified trans- N-(6-oxo-1,4,5,6-tetrahydropyrimidin-5-yl)benzamides with a good antimicrobial activity.

N-Heterocyclic carbene-catalyzed annulation of ynals with amidines: access to 1,2,6-trisubstituted pyrimidin-4-ones

A thiazolium-catalyzed annulation of ynals and amidines has been reported to construct pyrimidin-4-ones.