No abstract

Peptidoglycan, the exoskeleton of bacterial cell and an essential barrier that protects the cell, is synthesized by a pathway where the final steps are catalysed by transpeptidases. Knowledge of the structure and function of these vital enzymes that generate this macromolecule in M. tuberculosis could facilitate the development of potent lead compounds against tuberculosis. This review summarizes the experimental and computational studies to date on these aspects of transpeptidases in M. tuberculosis that have been identified and validated. The reported structures of L,D- and D,D-transpeptidases, as well as their functionalities, are reviewed and the proposed enzymatic mechanisms for L,D-transpeptidases are summarized. In addition, we provide bioactivities of known tuberculosis drugs against these enzymes based on both experimental and computational approaches. Advancing knowledge about these prominent targets supports the development of new drugs with novel inhibition mechanisms overcoming the current need for new drugs against tuberculosis.

COVID-19 pandemic has poses urgent health challenge, and this project aims to identify potential inhibitors to combat this virus. We screened 198 bioactive compounds from five selected medicinal plants previously reported to be antiviral against SARS-CoV-2 protease and two coreceptors followed by molecular dynamics simulations. From the screened compounds, Astragalin demonstrated very strong molecular interactions with the molecular docking binding energies −8.5, −8.0, −7.6 kcal/mol for 6LU7, 6LZG, and 6VXX proteins of SARS-CoV-2, respectively. Hydrogen bonding interaction with the active site catalytic residue HIS-41 or CYS-145 of the main protease SARS-CoV-2 was observed. Binding free energies (G bind) from MM-GBSA after 50 ns MD simulations showed that Astragalin has the highest energy of −33.00 and −34.89 kcal/mol in complex with the main protease and spike glycoprotein of SARS-CoV-2, respectively. The study identifies Astragalin as a better inhibitor for the inactivation of COVID-19 and should be pursued as a potential drug candidate for this virus.

No abstract

Two Schiff bases, (E)-1-(4-methoxyphenyl)-N-((E)-3-(4-nitrophenyl)allylidene)methanamine (compound 1) and (E)-N-((E)-3-(4-nitrophenyl)allylidene)-2-phenylethanamine (compound 2) have been synthesized and characterized using spectroscopic methods; time of flight MS, 1H and 13C NMR, FT-IR, UV–VIS, photoluminescence and crystallographic methods. The structural and electronic properties of compounds 1 and 2 in the ground state were also examined using the DFT/B3LYP functional and 6-31 + G(d,p) basis set, while the electronic transitions for excited state calculations were carried out using the TD-DFT/6-31 + G(d,p) method. The Schiff base compounds, 1 and 2 crystallized in a monoclinic crystal system and the P21/c space group. The emission spectra of the compounds are attributed to conjugated π-bond interaction while the influence of the intra-ligand charge transfer resulted in a broad shoulder for 1 and a double emission peak for 2. The calculated transitions at 450 and 369 nm for 1 and 2 respectively are in reasonable agreement with the experimental results. The higher values of dipole moment, linear polarizability and first hyperpolarizability of 1, suggest a better optical property and better candidate for the development of nonlinear optical (NLO) materials.