Compounds from myrtle flowers as antibacterial agents and SARS-CoV-2 inhibitors: In-vitro and molecular docking studies.

Plants and their related phytochemicals play a key role in the treatment of bacterial and viral infections, which inspire scientists to design and develop more efficient drugs starting from the phytochemical active scaffold. This work aims to characterize the chemical compounds of Myrtus communis essential oil (EO) from Algeria and to evaluate its in vitro antibacterial effect, as well as the in silico anti-SARS-CoV-2 activity. The chemical profile of hydrodistilled EO from myrtle flowers was determined using GC/MS analysis. The results showed qualitative and quantitative fluctuations and 54 compounds were identified including the main components: α-pinene (48.94%) and 1,8-cineole (28.3%) whereas other minor compounds were detected. The in vitro antibacterial activity of myrtle EO against Gram-negative bacteria was carried out by using the disc diffusion method. The best inhibition zone values ranged between 11 and 25 mm. The results revealed that Escherichia coli (25 mm), Klebsiella oxytoca (20 mm) and Serratia marcescens (20 mm) are the most susceptible strains to the EO which is endowed with a bactericidal effect. Furthermore, the antibacterial and anti-SARS-CoV-2 activities were investigated by the means of molecular docking (MD) study, in addition to ADME(Tox) analysis. The phytochemicals were docked against four targets: E. coli topoisomerase II DNA gyrase B (PDB: 1KZN), SARS-CoV-2 Main protease (PDB: 6LU7), Spike (PDB: 6ZLG) and angiotensin-converting enzyme II ACE2 (PDB: 1R42). The MD investigation revealed that 1,8-cineole could be the main phytochemical associated with the antibacterial activity of EO; s-cbz-cysteine, mayurone and methylxanthine were found the most promising phytochemicals against SARS-CoV-2; The ADME(Tox) analysis has shown their good druggability with no Lipinski's rule violation.

Facile green in situ hemisynthesis of new chiral chromeno-pyrimidine derivatives: antibacterial, antioxidant activities and molecular docking study.

A hemisynthesis 'in situ' reaction of (thio)barbituric acids with an α,ß-unsaturated aldehyde using perillaldehyde from Ammodaucus leucotrichus essential oil, afforded chromeno-pyrimidine derivatives B-1 and B-2. The reaction was carried out in water and water/ethanol medium without a catalyst. The obtained pyrimidines were identified by their spectral 1H,13C, Dept-135, HMBC, HSQC, COSY, and NOESY 2D. The antioxidant activity of both compounds was evaluated using different in vitro methods (DPPH, ABTS, and CUPRAC). The hemisynthesized molecules exhibited a bacteriostatic effect against ten tested gram (+) and gram (-) strains. According to the molecular docking analysis, B-1 showed lower binding energies compared to B-2 against (PDB: 1HD2) and (PDB: 1KZN) targets, which is in agreement with the ABTS and E. Coli assays. Furthermore, a probable promising anti-HIV activity was noticed against reverse transcriptase (PDB: 2RKI), a key enzyme for HIV replication. The ADME properties calculations showed no Lipinski's rule violation for both compounds.

Fisetin and Robinetin antiradical activity under solvent effect: density functional theory study.

The structural and antioxidant activity of two flavonols, namely, Fisetin and Robinetin, have been investigated employing the density functional theory (DFT) using B3LYP functional and 6-311++G (d, p) basis set. The calculations were performed in the gas phase and under the solvent effect of water, dimethylsulfoxide (DMSO), methanol, and benzene. The Hydrogen-Atom Transfer (HAT), single Electron Transfer Followed by Proton Transfer (SET-PT), and sequential Proton Loss Electron Transfer (SPLET) mechanisms were investigated to rationalize the radical scavenging capacities and to identify the favored antioxidant mechanism. Hence, the bond dissociation enthalpies (BDE) ionization potential (IP), IE, proton dissociation enthalpy (PDE), proton affinity (PA), and electron Transfer enthalpy (ETE) related to each mechanism were reported and discussed in function of the solvent effect. For both flavonols, the results showed that 4'-OH hydroxyl is the preferred active site following the trend 4'-OH > 3'-OH > 3-OH > (5'-OH) > 7-OH. Besides, the HAT mechanism is energetically the most favored pathway. The energetically favored solvents follow the trends water > DMSO > benzene > methanol and benzene > DMSO > methanol > water, for Fisetin and Robinetin, respectively.

Electronic structure and bonding of the dinuclear metal M2(CO)10 decacarbonyls: applications of natural orbitals for chemical valence.

The nature of the chemical metal-metal bond in M2(CO)10 (M = Mn, Re, Tc) dinuclear decacarbonyls complexes was investigated for the first time using the natural orbital chemical valence (NOCV) approach combined with the extended transition state (ETS) for energy decomposition analysis (EDA). The optimized geometries carried out at different levels of theory BP86, BLYP, BLYPD and BP86D, showed that the latter method, i.e., BP86D, led to the best agreement with X-ray experimental measurements. The BP86D/TZP results revealed that the computed covalent contribution to the metal-metal bond are 60.5%, 54.1% and 52.0% for Mn-Mn, Re-Re and Tc-Tc, respectively. The computed total interaction energies resulting from attractive terms (ΔE orb and ΔE eles), correspond well to experimental predictions, based on bond lengths and energy interaction analysis for the studied complexes.