Uncovering Antiviral Potential of <i>Cistus Ladanifer</i> Extracts Against Herpes Simplex Virus 1 and Severe Acute Respiratory Syndrome Coronavirus 2 by In Vitro and In Silico Analysis

Infectious diseases remain a major global health concern, leading to widespread complications and fatalities worldwide. Exploring the bioavailability of therapeutic compounds in traditional healing medicinal plants presents a promising approach to preventing and treating infectious diseases. Cistus ladanifer, a plant commonly employed in Moroccan traditional medicine, has been identified as a potential antiviral candidate. This study aimed to evaluate the antiviral activity of C. ladanifer extracts in vitro and in silico against the herpes simplex virus 1 and the severe acute respiratory syndrome coronavirus 2 variants of concern the Delta and Omicron. Toxic prediction of the main compounds identified by gas chromatography-mass spectrometry from C.ladanifer was performed in silico via ProTox-II software. Molecular docking was subsequently performed via Maestro version 11.5 software from Schrödinger to gain a comprehensive understanding of their biological activity. The extracts were subjected to in vitro antiviral screening against the selected strains via real-time quantitative polymerase chain reaction. Our docking estimation supported the in vitro results, and a diverse array of compounds extracted from C. ladanifer demonstrated significant antiviral activity with a low toxicity profile. Accordingly, in vitro data revealed a dose-dependent effect of the studied extracts, with particular efficacy against the Omicron variant. With the antiviral evaluation and docking outcomes in hand, we suggest a plausible mechanism of action for these compounds through further investigation into the effectiveness of C. ladanifer against other respiratory viruses.