Evaluation of the antiherpetical activities of Sideritis perfoliata L. subsp. perfoliata (Lamiaceae)

Herpes simplex viruses (HSV) are ubiquitous pathogens which cause a variety of diseases ranging in severity from mild to severe, and in certain cases, they can even become life threatening, especially in immunocompromized patients. HSV becomes latent mainly in trigeminal ganglia, after primary infection, and persists for the lifetime of the host with periodic reactivations. Nucleoside analogues, such as aciclovir (ACV), are the only approved drugs for the treatment of HSV infections. However, the widespread use of nucleoside-based drugs has led to the emergence of resistance in HSV.

Medicinal plants have been traditionally used for different kinds of ailments including infectious diseases. Continuing our chemotaxonomic examinations of the Greek flora belonging to Lamiaceae and our search for new compounds of pharmacological interest, we evaluate the aerial parts of Sideritis perfoliata subsp. perfoliata (a plant widely used in folk medicine in Greece since antiquity because of its antibacterial, anti-inflammatory, antirheumatic, anti-ulcer, digestive, and vaso-protective properties), for their virucidal activity or their abilities to inhibit HSV-1 propagation. Air-dried and powdered aerial parts of the above mentioned plant were extracted at room temperature with a series of solvents of increasing polarity, petroleum ether, CH₂Cl₂, MeOH, mixture of MeOH-H₂O 1:1 and H₂O. The dried extracts were dissolved in DMSO and tested for their ability to inhibit infection or delay the virus lytic cycle. Anti-HSV activities were found in dichloromethane extract. Bioguided fractionation of this extract led to the isolation of three active substances, which the mechanism of action is being evaluated.