Search

The single-stranded RNA genome of SARS-CoV-2 contains some G-quadruplex-forming G-rich elements which are putative drug targets. Here, we performed a ligand-based pharmacophore virtual screening of FDA approved drugs to find candidates targeting such RNA structures. Further in silico and in vitro assays identified three drugs as emerging SARS-CoV-2 RNA G-quadruplex binders.

A multidisciplinary approach, based on molecular dynamics/mechanics, ab initio calculations, dynamic docking studies, and chemical reactions, has been employed to gain insight into the mechanism of the antimalarial action of plakortin and dihydroplakortin, simple 1,2-dioxanes isolated from the sponge Plakortis simplex. Our results show that these molecules, after interaction of the endoperoxide bond with Fe(ii), likely coming from the heme molecule, give rise to the formation of an oxygen radical, followed by rearrangement to give a carbon radical centered on the "western" alkyl side-chain. The carbon radicals generated on the side-chain, amenable for intermolecular reactions, should represent the toxic intermediates responsible for subsequent reactions leading to plasmodium death. The minimal structural requirements necessary for the activity of this class of antimalarial agents have been identified and discussed throughout the paper.

The relative stereochemistry of 13,19-didesmethyl spirolide C was determined through careful analysis of NMR parameters strongly dependent upon molecular conformations supported and extended by computational studies. This work has also shed light on the conformational behavior of spirolides in solution. An equilibrium between two possible conformers of the identified diastereoisomer was inferred, while the uncommon cyclic imine moiety of spirolides-the putative pharmacophore of this class of toxins-was interestingly found to adopt only a single dominant conformation. The insightful details provided on spirolide conformations may represent a key means to pharmacologists involved in clarifying the mechanism of action of spirolide, which is yet to be totally defined.