Linalool for COVID-19

The COVID-19 pandemic has reignited interest in traditional medicinal plants as potential therapeutic agents. This study examined the chemical composition, cytotoxicity, and antimicrobial activity of essential oils from six Moroccan medicinal plants, namely, Eucalyptus globulus, Artemisia absinthium, Syzygium aromaticum, Thymus vulgaris, Artemisia alba, and Santolina chamaecyparissus, which are commonly used by the Moroccan population for COVID-19 prevention. The chemical composition of each essential oil was determined using gas chromatography–mass spectrometry (GC–MS) to identify key compounds. Cytotoxicity was evaluated in the Vero E6 cell line, which is frequently used in SARS-CoV-2 research, using the neutral red assay, with oil concentrations ranging from 25 to 100 µg/mL. Antimicrobial activity was tested against standard reference strains, including Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 25923), Candida albicans (ATCC 10231), and Bacillus subtilis (ATCC 6633), using the disc diffusion method. GC–MS analysis revealed significant components such as spathulenol (15%) and caryophyllene oxide (7.67%) in Eucalyptus globulus and eugenol (54.96%) in Syzygium aromaticum. Cytotoxicity assays indicated that higher concentrations of essential oils significantly reduced cell viability, with Thymus vulgaris showing the highest IC50 (8.324 µM) and Artemisia absinthium the lowest (18.49 µM). In terms of antimicrobial activity, Eucalyptus globulus had the strongest effect, with a 20 ± 0.00 mm inhibition zone against Bacillus subtilis, whereas both Syzygium aromaticum and Artemisia herba-alba had a 12.25 ± 0.1 mm inhibition zone against the same strain. These findings suggest that these essential oils have significant therapeutic potential, particularly in combating antimicrobial resistance and exerting cytotoxic effects on viral cell lines. Further research is necessary to explore their mechanisms of action and ensure their safety for therapeutic use.

The search for effective therapeutics against COVID-19 remains imperative, and natural compounds have emerged as promising candidates. Our study explores the potential of bioactive phytochemicals from the traditional Siddha formulation MilagaiKudineer as inhibitors against key target proteins of the SARS-CoV-2 virus. Through in-silico docking analyses, the interactions of phytochemicals from Cuminum cyminum, Curcuma longa, and Capsicum annuum with the receptor-binding domain of the SARS-CoV-2 spike glycoprotein (PDB ID: 6VSB), the SARS-CoV2 RNA-dependent RNA polymerase (PDB ID: 6NUR), and the main protease, 3CL pro (PDB ID: 6LU7) were examined. Notable compounds such as Curcumin, Quercetin, Capsaicin, and Ascorbic acid demonstrated significant binding affinities towards these viral targets, suggesting mechanisms by which these phytochemicals may disrupt viral entry and replication. Our findings also highlight the potential of compounds like Carvacrol, Cuminaldehyde, Linalool, and Dihydrocapsaicin in mediating antiviral effects by interfacing with key amino acid residues of the spike glycoprotein. These interactions are indicative of their capacity to hinder the virus-host cellbinding process. Moreover, the interaction of select phytochemicals with the SARS-CoV2 RNA-dependent RNA polymerase and the 3CLpro enzyme suggests a possible inhibitory effect on viral replication. Given the promising interactions observed, these phytochemicals warrant further investigation through in vitro and in vivo studies to validate their antiviral efficacy against COVID-19. This research underscores the importance of exploring traditional medicinal formulations for potential therapeutic agents in the fight against emerging infectious diseases.