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.

A hemisynthesis 'in situ' reaction of (thio)barbituric acids with an α,β-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.