Marine algal antagonists targeting 3CL protease and spike glycoprotein of SARS-CoV-2: a computational approach for anti-COVID-19 drug discovery.

The COVID-19 pandemic has severely destructed human life worldwide, with no suitable treatment until now. SARS-CoV-2 virus is unprecedented, resistance against number of therapeutics and spreading rapidly with high mortality, which warrants the need to discover new effective drugs to combat this situation. This current study is undertaken to explore the antiviral potential of marine algal compounds to inhibit the viral entry and its multiplication using computational analysis. Among the proven drug discovery targets of SARS-CoV-2, spike glycoprotein and 3-chymotrypsin-like protease are responsible for the virus attachment and viral genome replication in the host cell. In this study, the above-mentioned drug targets were docked with marine algal compounds (sulfated polysaccharides, polysaccharide derivatives and polyphenols) using molecular docking tools (AutoDockTools). The obtained results indicate that κ-carrageenan, laminarin, eckol, trifucol and ß-D-galactose are the top-ranking compounds showing better docking scores with SARS-CoV-2 targets, than the current experimental COVID-19 antiviral drugs like dexamethasone, remdesivir, favipiravir and MIV-150. Further, molecular dynamic simulation, ADMET and density functional theory calculations were evaluated to substantiate the findings. To the best of our knowledge, this is the first report on in silico analysis of aforesaid algal metabolites against SARS-CoV-2 targets. This study concludes that these metabolites can be curative for COVID-19 in the hour of need after further validations in in vitro and in vivo testings.Communicated by Ramaswamy H. Sarma.

Anthracene-based fluorescent probe: Synthesis, characterization, aggregation-induced emission, mechanochromism, and sensing of nitroaromatics in aqueous media.

The sensitive and selective detection of nitroexplosive molecules thorough a simple methodology has received a significant field of research affecting global security and public safety. In the present study, the synthesis of anthracene-based chalcone (S1) was conducted using a simple condensation method. S1 was found to exhibit unique properties, such as aggregation-induced emission in solution and mechanochromic behavior in solid state. A fluorescent aggregate was applied to sense electron-deficient picric acid (PA) and 2,4-dinitrophenol (2,4-DNP) in an aqueous solution. Notably, the developed test strip-based sensor (S1) could be used to effectively detect PA and 2,4-DNP, which were visualized by the naked eye. Photophysical analysis revealed the occurrence of an electron transfer from electron-rich S1 to the electron-deficient nitro compounds, which was confirmed using density functional theory and 1H-nuclear magnetic resonance studies. In addition, the observed results confirmed the simple synthesis of S1 as a promising material for the development of test strip-based sensor devices for the detection of toxic and explosive aromatic nitro molecules.

Novel star-shaped D-π-D-π-D and (D-π)2-D-(π-D)2 anthracene-based hole transporting materials for perovskite solar cells.

Three types of novel star-shaped molecular architectures, D-π-D-π-D and (D-π)2-D-(π-D)2 anthracene (ANTTPA, AOME, AOHE) based hole transporting materials, are designed for hybrid perovskite solar cells using the Gaussian 09 computation program with the B3LYP/6-31g (d, p) basis set level. The HOMO energy level of the designed materials has a higher HOMO energy level compared to the perovskite HOMO energy level, which is more facile for hole transport from the hole transporting layer to the oxidized perovskite layer. Thereafter, anthracene-based derivatives were synthesized from Buchwald-Hartwig and Mizoroki-Heck cross coupling reactions. The behaviors of the transporting charges were determined by both UV-visible absorbance and emission spectroscopy through solvatochromism experiments. Furthermore, the electrochemical properties also proved that the synthesized compounds had an optimal HOMO energy level in the TiO2/perovskite/HTM interface. Our hole transport materials (HTMs) have a good film formation compared to the spiro-OMeTAD, which was confirmed from scanning electron microscopy images. The obtained theoretical and experimental data show the suitability of designing anthracene-based derivatives with the potential to be used as hole transporting materials in organic-inorganic hybrid perovskite solar cells.

Turn-on Fluorescence Chemosensor for Zn2+ Ion Using Salicylate Based Azo Derivatives and their Application in Cell-Bioimaging.

The synthesis and optical studies of salicylate based azo derivatives (DPSAD and IPSAD) are reported. The receptors act as a versatile fluorogenic chemosensor for Zn2+ causing a selective enhancement of fluorescence over other competing cations. The complex formed between receptors and Zn2+ are identified on the basis of absorption and fluorescence titration and further confirmed by ESI-MS. DFT/TD-DFT calculations support the observed optical changes happens only upon complexation with Zn2+ ion. Moreover, receptors are further applied to intracellular sensing and imaging studies. Graphical Abstract Salicylate based azo derivatives (DPSAD and IPSAD) as fluorogenic chemosensor for the detection of Zn2+ ion.