Antimicrobial activity of ethanolic and aqueous extracts of medicinally used tree ferns Alsophila cuspidata and Cyathea microdonta

Medicinal plants are important components of traditional medicine and sources of novel antimicrobial compounds against drug resistance pathogen strains. This study tested the antimicrobial activity of ethanolic and aqueous extracts of medicinally used Neotropical tree ferns Cyathea microdonta and Alsophila cuspidata against gram positive bacteria and gram negative bacteria using the Kirby-Bauer disc diffusion method. Highest antimicrobial activity was observed in ethanolic extracts, and extracts were more active against gram positive bacteria than gram negative bacteria. No difference was observed in antimicrobial activity between species or between extracts made from the leaves, stipe, or caudex. These results suggest that the traditional use of tree fern mucilage as a topical agent for cuts and leishmaniasis lesions may reduce risk of secondary infection with skin bacteria such as Staphylococcus aureus, and that Neotropical Cyatheaceae are a potential source of novel antimicrobial compounds.