Antiviral activity-guided fractionation from Araucaria angustifolia leaves extract

Ethnopharmacological relevance: Araucaria angustifolia (Bert.) O. Kuntze (Araucariaceae) is a Brazilian medicinal plant traditionally used for the treatment of various illnesses including dried skin, wounds, shingles, and sexually transmitted diseases. Aim of the study: The rationale of the study was to provide evidence of its antiherpes activity in order to confirm its popular use that could be related to herpes disease. Materials and methods: The crude hydroethanolic extract (HE) obtained from Araucaria angustifolia leaves was submitted to a sequential liquid-liquid extraction with solvents of increased polarity. The HE and fractions obtained were evaluated for cytotoxicity and antiherpes activity (Herpes Simplex Virus type 1) by MTT assay. The most active fractions were selected to perform an in vitro antiviral activity-guided chromatographic fractionation. Results: The ethyl acetate (EA) and n-butanol (NB) fractions have shown the best results for antiherpetic activity and their further fractionation yielded 22 subfractions. From these subfractions, 14 were active, and the most potent antiherpetic activity was obtained for NB1-4 subfraction with selectivity index (SI) of 57.51. Chemical analysis of NBI-4 subfractions revealed the presence of proanthocyanidins and the known biflavonoids (bilobetin, II-7-O-methyl-robustaflavone and cupressuflavone). The same biflavonoids have been detected in EA subfractions. Conclusion: The present study has shown that the hydroethanolic extract from Araucaria angustifolia leaves as well as many different fractions and subfractions exhibited antiherpes activity, supporting the use of this plant species in folk medicine. (C) 2009 Elsevier Ireland Ltd. All rights reserved.