Design and evaluation of novel piperidine HIV-1 protease inhibitors with potency against DRV-resistant variants

Synthesis of Spiro[indoline-pyridine]-dicarboxylates and Substituted Alkylidene Oxindoles by Azomethine Ylides and MBH Carbonates of Isatins

We have developed an efficient protocol for the synthesis of spiro[indoline-pyridine]dicarboxylates and substituted alkylidene oxindoles through [3 + 3] cycloaddition and Michael addition individually by azomethine ylides and various MBH carbonates of isatins. The selective generation of cyclic products and chain products was achieved by changing the substituents at the 3-position of the oxindoles. The features of this method include convenient catalysts, mild reaction conditions, and broad substrate scopes.

N-Heterocycles as Promising Antiviral Agents: A Comprehensive Overview

Viruses are a real threat to every organism at any stage of life leading to extensive infections and casualties. N-heterocycles can affect the viral life cycle at many points, including viral entrance into host cells, viral genome replication, and the production of novel viral species. Certain N-heterocycles can also stimulate the host's immune system, producing antiviral cytokines and chemokines that can stop the reproduction of viruses. This review focused on recent five- or six-membered synthetic N-heterocyclic molecules showing antiviral activity through SAR analyses. The review will assist in identifying robust scaffolds that might be utilized to create effective antiviral drugs with either no or few side effects.

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.

Design, synthesis, and biological evaluation of novel HIV-1 protease inhibitors containing pyrrolidine-derived P2 ligands to combat drug-resistant variant

The design, synthesis, and biological evaluation of a novel series of HIV-1 protease inhibitors containing pyrrolidines with diverse linkers as the P2 ligands and various aromatic derivatives as the P2' ligands were described. A number of inhibitors demonstrated potent efficacy in both enzyme and cellular assays, as well as relatively low cytotoxicity. In particular, inhibitor 34b with a (R)-pyrrolidine-3-carboxamide P2 ligand and a 4-hydroxyphenyl P2' ligand displayed exceptional enzyme inhibitory activity with an IC₅₀ value of 0.32 nM. Furthermore, 34b also exhibited robust antiviral activity against both wild-type HIV-1 and drug-resistant variant with low micromolar EC₅₀ values. In addition, the molecular modelling studies revealed the extensive interactions between inhibitor 34b and the backbone residues of both wild-type and drug-resistant HIV-1 protease. These results suggested the feasibility of utilizing pyrrolidine derivatives as the P2 ligands and provided valuable information for further design and optimization of highly potent HIV-1 protease inhibitors.

Ultrasound-Assisted Synthesis of Piperidinyl-Quinoline Acylhydrazones as New Anti-Alzheimer's Agents: Assessment of Cholinesterase Inhibitory Profile, Molecular Docking Analysis, and Drug-like Properties

Alzheimer's disease (AD) is one of the progressive neurological disorders and the main cause of dementia all over the world. The multifactorial nature of Alzheimer's disease is a reason for the lack of effective drugs as well as a basis for the development of new structural leads. In addition, the appalling side effects such as nausea, vomiting, loss of appetite, muscle cramps, and headaches associated with the marketed treatment modalities and many failed clinical trials significantly limit the use of drugs and alarm for a detailed understanding of disease heterogeneity and the development of preventive and multifaceted remedial approach desperately. With this motivation, we herein report a diverse series of piperidinyl-quinoline acylhydrazone therapeutics as selective as well as potent inhibitors of cholinesterase enzymes. Ultrasound-assisted conjugation of 6/8-methyl-2-(piperidin-1-yl)quinoline-3-carbaldehydes (4a,b) and (un)substituted aromatic acid hydrazides (7a-m) provided facile access to target compounds (8a-m and 9a-j) in 4-6 min in excellent yields. The structures were fully established using spectroscopic techniques such as FTIR, ¹H- and ¹³C NMR, and purity was estimated using elemental analysis. The synthesized compounds were investigated for their cholinesterase inhibitory potential. In vitro enzymatic studies revealed potent and selective inhibitors of AChE and BuChE. Compound 8c showed remarkable results and emerged as a lead candidate for the inhibition of AChE with an IC₅₀ value of 5.3 ± 0.51 µM. The inhibitory strength of the optimal compound was 3-fold higher compared to neostigmine (IC₅₀ = 16.3 ± 1.12 µM). Compound 8g exhibited the highest potency and inhibited the BuChE selectively with an IC₅₀ value of 1.31 ± 0.05 µM. Several compounds, such as 8a-c, also displayed dual inhibitory strength, and acquired data were superior to the standard drugs. In vitro results were further supported by molecular docking analysis, where potent compounds revealed various important interactions with the key amino acid residues in the active site of both enzymes. Molecular dynamics simulation data, as well as physicochemical properties of the lead compounds, supported the identified class of hybrid compounds as a promising avenue for the discovery and development of new molecules for multifactorial diseases, such as Alzheimer's disease (AD).

Structure based design and evaluation of benzoheterocycle derivatives as potential dual HIV-1 protease and reverse transcriptase inhibitors

The development of dual inhibitors of HIV-1 protease and reverse transcriptase is an attractive strategy for multi-target therapeutic of AIDS, which may be privileged in delaying the occurrence of drug resistance. We herein designed a novel kind of dual inhibitors with benzofuran or indole cores. Biological results showed that a number of inhibitors displayed significant activity against both HIV-1 protease and reverse transcriptase. Among which, inhibitor 10f exhibited a good correlation with an approximate ratio of 1: 2 between the two enzymes. Furthermore, the dual inhibitors illustrated similar potency against both the wild-type virus and drug-resistant mutant. In addition, the molecular dynamic simulation studies verified the dual actions of such inhibitors.

A kind of HIV-1 protease inhibitors containing phenols with antiviral activity against DRV-resistant variants

Based upon the preliminary design of enhancing genetic barrier to drug-resistant viral mutants by maximizing hydrogen-bonding or other van der Waals contacts, we have designed, synthesized and biologically evaluated a new class of HIV-1 protease inhibitors with phenol derived P2 ligands and nitro or halogens in P2' ligands. Results indicate that a majority of inhibitors exhibit robust enzyme inhibitory with IC₅₀ values in picomolar or single digit nanomolar ranges. Among which, compound 17d displays potency with IC₅₀ value of 21 pM and high protease selectivity. Of note, 17d exhibits greater antiviral activity against the DRV-resistant variant than the efficacy against the wild type virus. Furthermore, the molecular modeling studies demonstrate important interactions between 17d and the active sites of both the wild-type and DRV-resistant HIV-1 protease, as well as furnish insights for further optimization of new inhibitors.