Case study-based review on misassigned structures and measures to avoid erroneous assignments during structure determination.

Many plants of boreal forest of Quebec have been used by Native Americans to treat a variety of microbial infections. However, the antiviral activities of these plants have been seldom evaluated on cellular models to validate their in vitro efficiencies. In this study, Cornus canadensis L. (Cornaceae), a plant used in Native American traditional medicine to treat possible antiviral infections, has been selected for further examination. The plant was extracted by decoction and infusion with water, water/ethanol 1:1 and ethanol to obtain extracts similar to those used by Native Americans. The effects of the extracts were tested on herpes simplex virus type-1 (HSV-1) using a plaque reduction assay. Moreover, bioassay-guided fractionation was achieved to isolate bioactive compounds. Water/ethanol 1:1 infusion of C. canadensis leaves were the most active extracts to inhibit virus absorption with EC50 of about 9 μg mL−1, whereas for direct mode, both extraction methods using water or water/ethanol 1:1 as solvent were relatively similar with EC50 ranging from 11 to 17 μg mL−1. The fractionation led to the identification of active fractions containing hydrolysable tannins. Tellimagrandin I was found the most active compound with an EC50 of 2.6 μM for the direct mode and 5.0 μM for the absorption mode. Altogether, the results presented in this work support the antiviral activity of Cornus canadensis used in Native American traditional medicine.