Non-nucleoside structured compounds with antiviral activity—past 10 years (2010–2020)

Computational identification of drug-like marine natural products as potential RNA polymerase inhibitors against Nipah virus

Nipah virus (NiV) has been an alarming threat to human populations in southern Asia for more than a decade. It is one of the most deadly viruses in the Mononegavirales order. Despite its high mortality rate and virulence, no chemotherapeutic agent or vaccine is publicly available. Hence, this work was conducted to computationally screen marine natural products database for drug-like potential inhibitors for the viral RNA-dependent RNA polymerase (RdRp). The structural model was subjected to molecular dynamics (MD) simulation to obtain the native ensemble of the protein. The CMNPDB dataset of marine natural products was filtered to retain only compounds following Lipinski's five rules. The molecules were energy minimized and docked into different conformers of the RdRp using AutoDock Vina. The best 35 molecules were rescored by GNINA, a deep learning-based docking software. The resulting nine compounds were evaluated for their pharmacokinetic profiles and medicinal chemistry properties. The best five compounds were subjected to MD simulation for 100 ns, followed by binding free energy estimation via Molecular Mechanics/ Generalized Born Surface Area (MM/GBSA) calculations. The results showed remarkable behavior of five hits as inferred by stable binding pose and orientation to block the exit channel of RNA synthesis products in the RdRp cavity. These hits are promising starting materials for in vitro validation and structural modifications to enhance the pharmacokinetic and medicinal chemistry properties for developing antiviral lead compounds.

Guignardones Y-Z, antiviral meroterpenes from Penicillium sp. NBUF154 associated with a Crella sponge from the marine mesophotic zone

Guignardones Y-Z (1-2), two new meroterpenoids, and six known metabolites involving guignardone A-H (3-4), gyorgy-isoflavone (5), daidzein (6), blumenol A (7) and guignardianone A (8) were isolated from the fungus Penicillium sp. NBUF154, which was obtained from a 60 m deep Crella sponge. Their structures including absolute configurations were unambiguously elucidated by exhaustive spectroscopic analysis and ECD calculations. A putative biosynthetic pathway toward guignardones (1-4) is here proposed. Biological evaluation of compounds 1-8 showed that 1 and 7 exert potent inhibitory effects towards human enterovirus 71 (EV71).

Fluorinated Analogues of Lepidilines A and C: Synthesis and Screening of Their Anticancer and Antiviral Activity

Starting with fluorinated benzylamines, a series of 2-unsubstituted imidazole N-oxides was prepared and subsequently deoxygenated in order to prepare the corresponding imidazoles. The latter were treated with benzyl halides yielding imidazolium salts, which are considered fluorinated analogues of naturally occurring imidazolium alkaloids known as lepidilines A and C. A second series of oxa-lepidiline analogues was obtained by O-benzylation of the initially synthetized imidazole N-oxides. Both series of imidazolium salts were tested as anticancer and antiviral agents. The obtained results demonstrated that the introduction of a fluorine atom, fluoroalkyl or fluoroalkoxy substituents (F, CF₃ or OCF₃) amplifies cytotoxic properties, whereas the cytotoxicity of some fluorinated lepidilines is promising in the context of drug discovery. All studied compounds revealed a lack of antiviral activity against the investigated viruses in the nontoxic concentrations.