Context The persistent spread of highly contagious COVID-19 disease is one of the deadliest occurrences in the history of mankind. Despite the distribution of numerous efficacious vaccines and their extensive usage, the perpetual effectiveness of immunization is being catechized. Therefore, discovering an alternative therapy to control and prevent COVID-19 infections has become a top priority. The main protease (M pro ) plays a key role in viral replication, making it an intriguing pharmacological target for SARS-CoV-2. Methods In this context, virtual screening of thirteen bioactive polyphenols and terpenoids of Rosmarinus officinalis L. was performed using several computational modules including molecular docking, ADMET, drug-likeness characteristics, and molecular dynamic simulation to predict the potential inhibitors against SARS-CoV-2 M pro (PDB: 6LU7). The results suggest that apigenin, betulinic acid, luteolin, carnosol, and rosmarinic acid may emerge as potential inhibitors of SARS-CoV-2 with acceptable drug-likeness, pharmacokinetics, ADMET characteristics, and binding interactions comparable with remdesivir and favipiravir. These findings imply that some of the active components of Rosmarinus officinalis L. can serve as an effective antiviral source for the development of therapeutics for SARS-CoV-2 infection. Supplementary Information The online version contains supplementary material available at 10.1007/s00894-023-05569-6.

Background: The plant Sterculia urens Roxb. of Malvaceae family is comparatively understudied. Genus Sterculia is widely recognized by its phytomedicinal and ethnomedicinal attributes. The study is aimed to evaluate the qualitative analysis, Fourier transform infrared (FT-IR), thin layer chromatography (TLC), total phenolic content (TPC), antioxidant and antimicrobial activities of the crude hydro-methanolic extract of S. urens root. Results: The antioxidant activity, antimicrobial assay for clinical isolates, and TPC were measured by DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging activity, agar well diffusion method, and Folin-Ciocalteu assay respectively. Hydromethanolic extract confirmed the presence of alkaloids, flavonoids, tannins, phenols, saponins, steroids, and glycosides as primary and secondary metabolites, which was later confirmed by TLC. FT-IR spectroscopy revealed the presence of alkanes, alkenes, alkyl halides, halogen compounds, primary alcohol, tertiary alcohol, aldehyde, aromatic amine, secondary amines, amide group, and carboxylic acid. The crude extract was composed of a significant quantity of total phenolic content with 705 ± 0.40 mg GAE/g. Synergistically, the IC 50 value of the crude extract and ascorbic acid was found to be 27.055 μg/ml and 37.244 μg/ml, respectively, which suggests that root extract possesses strong antioxidant properties. The majority of the microbial strains exhibited varying degrees of sensitivity to the root extract with a notable inhibitory effect against Escherichia coli, Klebsiella pneumoniae, and Penicillium glaucum. Conclusion:The findings of this analysis suggest that the hydro-methanolic extract from S. urens root exhibit antioxidant activity quantified by its ability to scavenge DPPH; antimicrobial activity displayed appreciable microbial sensitivity. These properties are associated with the presence of high phenolic content, different secondary metabolites, and their functional groups. The results are suggestive that S. urens root is rich in bioactive compounds, which serve as a novel natural source for potential therapeutic applications.