Herpes virus inhibitory substances from Hypericum connatum Lam., a plant used in southern Brazil to treat oral lesions

Hypericum connatum (Guttiferae) is used in southern Brazil in the treatment of lesions in the mouth, often related to acute herpetic gingivo-stomatitis. The chemical investigation of the plant revealed the presence of phloroglucinol derivatives and flavonoids. From the n-hexane extract of the aerial parts a phloroglucinol derivative, hyperbrasilol B, was isolated, while the methanolic extract afforded four flavonoids: amentoflavone, hyperoside, guaijaverine and luteoforol. The crude methanolic extract and fractions (n-hexane, dichloromethane and methanol) as well as the isolated compounds were tested for antiviral activity against herpes simplex viruses (HSV). Among the tested samples, luteoforol was the most active inhibiting the cytopathic effect (CPE) and reducing the viral titer of HSV-1 DNA viral strains KOS and VR733 (ATCC).