Research: BINNS and colleagues,

BINNS and colleagues, Ottawa-Carleton Institute of Biology, University of Ottawa, Canada evaluated the phototoxic antimicrobial (antifungal) activity of Echinacea extracts.

Extracts of Echinacea have previously been reported to contain acetylenic isobutylamides and polyacetylenes . This study aimed to confirm the presence of these compounds and demonstrate that such plant extracts have phototoxic antifungal activity.

HPLC (high-pressure liquid chromatography) was used to confirm the presence of polyacetylenes and alkylamides in different organs in Echinacea purpurea. The abilities of hexane extr acts of Echinacea to inhibit growth of different yeast strains, under near UV irradiation (phototoxicity) or without irradiation, were investigated.

Hexane extracts inhibited the growth of the following yeast strains to varying degrees: Saccharomyces cerevisiae, Candida shehata, C. kefyr, C. albicans, C. steatulytica and C. tropicalis . Inhibition was greater under near UV irradiation (phototoxicity) compared with no irradiation (conventional antifungal activity). Two representative pure compounds, undeca-2E,4Z-diene-8,10-diynoic acid isobutylamide and dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamide, were isolated from Echinacea root extracts and compared in a disk assay (5 ug/disk) with the highly conjugated trideca-1-ene-3,5,7,9,10-pentayne (previously isolated in this laboratory and found here in E. purpurea). Of the three compounds, only the pure trideca-1-ene-3,5,7,9,10-pentayne demonstrated significant phototoxicity .

The study demonstrated that extracts of Echinacea had phototoxic activity against a range of fungi, including clinically relevant pathogenic fungi . Phototoxic activity of Echinacea extracts was related to the presence of polyacetylenes and alkylamides . Specifically, the phototoxic activity of Echinacea species was attributed primarily to the ketoalkenes and ketoalkynes abundantly present in its roots .

Binns SE et al. Light-mediated antifungal activity of Echinacea extracts. Planta Medica 66 (3): 241-4. Apr 2000.

The above study demonstrates the wide-ranging anti-fungal activity of Echinacea, particularly against Candida strains, one of the gold standards used in herbal medicine to fight infection.