Antimicrobial activity of extracts of eastern North American hardwood trees and relation to traditional medicine

Wood and bark extracts of 14 eastern North American hardwood tree species w hich were used traditionally as medicine by First Nation's people were scre ened for antimicrobial activities with eight strains of bacteria and six st rains of fungi, Eighty-six percent of the bark extracts were active against methicillin sensitive Staphylococcus aureus; 71% against Bacillus subtilus and 79% against Mycobacterium phlei. The bark extract of Juglans cinerea e n was active against Pseudomonas aeruginosa 187, Salmonella typhiumurium, a nd Klebsiella pneumoniae. The wood extracts were less active: 72% were acti ve against S. aureus (methicillin-sensitive), 36% against B. subtilus and 4 3% against M. phlei. Results from antifungal tests indicated that 36% of th e extracts were active against at least one fungal strain and that bark,ext racts were more active than wood extracts. The bark extract from Juglans ci nerea had the broadest spectrum of activities against Candida albicans, Sac charomyces cerevisiae, Cryptococcus neoformans, Trichophyton mentagrophytes Miclosporum gypseum, and Aspergillus fumigatus. In general, the extracts w ere more active against gram positive bacteria than gram negative bacteria and against filamentous fungi than yeast-like fungi. The study also demonst rated a correlation between frequency of traditional medicinal use by the F irst Nations people and antimicrobial activity of extracts indicating that the traditional knowledge encompasses an understanding of aspects of chemic al ecology. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.