Antiviral activity-guided fractionation from Araucaria angustifolia leaves extract

Ethnopharmacological relevanceAraucaria 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 studyThe 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 methodsThe 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.ResultsThe 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 NB1-4 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.ConclusionThe 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.

Scheme of the antiviral activity-guided fractionation from Araucaria angustifolia leaves extract. The crude hydroethanolic extract (HE), its five fractions [petroleum ether (PE), dichloromethane (DCM), ethyl acetate (EA), n-butanol (NB) and aqueous residue (AR)], and their derived subfractions were evaluated for cytotoxicity and antiherpetic activity. The isolated substances corresponding to each subfraction are shown in parentheses. Numbers between parentheses represent the selectivity index values of bioactive samples.Figure optionsDownload as PowerPoint slide