Design, Synthesis, Evaluation and Molecular Dynamics Simulation of Dengue Virus NS5-RdRp Inhibitors

Dengue virus (DENV) is a major mosquito-borne human pathogen in tropical countries; however, there are currently no targeted antiviral treatments for DENV infection. Compounds 27 and 29 have been reported to be allosteric inhibitors of DENV RdRp with potent inhibitory effects. In this study, the structures of compounds 27 and 29 were optimized using computer-aided drug design (CADD) approaches. Nine novel compounds were synthesized based on rational considerations, including molecular docking scores, free energy of binding to receptor proteins, predicted Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) parameters, structural diversity, and feasibility of synthesis. Subsequently, the anti-DENV activity was assessed. In the cytopathic effect (CPE) assay conducted on BHK-21 cells using the DENV2 NGC strain, both SW-b and SW-d demonstrated comparable or superior activity against DENV2, with IC50 values of 3.58 ± 0.29 μM and 23.94 ± 1.00 μM, respectively, compared to that of compound 27 (IC50 = 19.67 ± 1.12 μM). Importantly, both SW-b and SW-d exhibited low cytotoxicity, with CC50 values of 24.65 μmol and 133.70 μmol, respectively, resulting in selectivity indices of 6.89 and 5.58, respectively. Furthermore, when compared to the positive control compound 3'-dATP (IC50 = 30.09 ± 8.26 μM), SW-b and SW-d displayed superior inhibitory activity in an enzyme inhibitory assay, with IC50 values of 11.54 ± 1.30 μM and 13.54 ± 0.32 μM, respectively. Molecular dynamics (MD) simulations elucidated the mode of action of SW-b and SW-d, highlighting their ability to enhance π-π packing interactions between benzene rings and residue W795 in the S1 fragment, compared to compounds 27 and 29. Although the transacylsulphonamide fragment reduced the interaction between T794 and NH, it augmented the interaction between R729 and T794. In summary, our study underscores the potential of SW-b and SW-d as allosteric inhibitors targeting the DENV NS5 RdRp domain. However, further in vivo studies are warranted to assess their pharmacology and toxicity profiles.

Synthesis, Cytotoxic and Heparanase Inhibition Studies of 5-oxo-1-arylpyrrolidine-3- carboxamides of Hydrazides and 4-amino-5-aryl-4H-1,2,4-triazole-3-thiol

Design of chemically novel, biologically potent small heterocyclic molecules with anticancer activities, which targets the enzyme heparanase has gained prominent clinical interest. We have synthesized a novel class of carboxamide derivatives by coupling various substituted aromatic acid hydrazides and triazoleamine with pyrrolidine carboxylic acid by using coupling agents. The synthesized compounds are characterized by spectroscopic techniques such as FT-IR, HRMS and NMR. These compounds are investigated for cytotoxicity on different cancer cell lines and heparanase inhibitory activity. Most of them showed moderate heparanase inhibitory activity and good cytotoxicity.

Floro-pyrazolo[3,4-d]pyrimidine derivative as a novel plant activator induces two-pathway immune system

Plants are known to develop a multi-faceted innate immune system for pathogenic defense. Systemic acquired resistance (SAR) and induced systemic resistance (ISR) are the two main pathways. Many chemical inducers known as plant activators that activate innate immunity to defend against pathogens have been discovered. Currently, the exploitation of new plant activators is mainly done to develop analogs of salicylic acid as SAR-signaling molecules; however, the ISR pathway is hardly investigated for new plant activators. Based on recent studies on 1-methyl pyrazolo [3,4-d]pyrimidine bioactivity and ATP-induced resistance to biotrophic and necrotrophic pathogens, a new lead compound, 1-methyl-4-amino-pyrazolo [3,4-d]pyrimidine, was obtained as a new scaffold of plant activators for possible inducing ISR immunity system. Additionally, fluorine atom plays an important role in the design and development of new pesticides due to the unique physical chemistry effect, a series of pyrazolo [3,4-d]pyrimidine derivatives were designed and synthesized. Several compounds showed good broad-spectrum induced resistance in vivo, but there was no direct antibacterial activity in vitro. Notably, the introduction of fluorine atom at the para-position of the benzene ring greatly enhanced the induction activity of P1d both involved in SAR and ISR pathways, which implied the inducing resistance both in defending pathogens and insects.

3(2H)-pyridazinone derivatives: a new scaffold for novel plant activators

Due to the emergence of drug resistance, pesticide residue and environmental contamination, it is important to develop novel eco-friendly strategies to protect plants.