Antimicrobial activity of native and naturalized plants of Minnesota and Wisconsin

The antimicrobial activity of aqueous ethanol extracts of stems, leaves, flowers and roots from 336 native and naturalized species (597 extracts) collected in Minnesota and Wisconsin was tested against Staphylococcus aureus,Escherichia coli, Pseudomonas aeruginosa and Candida albicans. Twenty-four percent, or 142 extracts, exhibited antimicrobial activity. Extracts from Betula papyrifera Marshall (Betulaceae), Centaurea maculosa Lam. (Asteraceae),Epilobium angustifolium L. (Onagraceae), Hypericum perforatum L. (Clusiaceae),Lythrum salicaria L. (Lythraceae), and Rhus glabra L. (Anacardiaceae) inhibited all four microorganisms. Extracts from two species inhibited three microorganisms, 11 extracts (10 species) inhibited two, and 119 extracts (98 species) inhibited one microorganism with four species having inhibition zones greater than 15 mm. This is the first report describing the antimicrobial activity ofClintonia sp. (Liliaceae), Comptonia peregrina (L.) J.M. Coult. (Myricaceae),Desmodium illinoense A. Gray (Fabaceae), Geum virginianum L. (Rosaceae), leaves of Scirpus americanus Pers. (Cyperaceae), flower clusters of Eupatorium maculatum L. (Asteraceae), berries of Smilacina racemosa (L.) Desf (false Solomon’s seal) and frozen Hypericum perforatum L. (Clusiaceae).   Key words:  Antimicrobial, medicinal, native plants, antibacterial.