The Action of Plant Extracts on a Bacteriophage of Pseudomonas pyocyanea and on Influenza A Virus

SUMMARY: Extracts of 288 plants, mostly British, were examined for suppressive action on the development of a bacteriophage of Pseudomonas pyocyanea. Many possessed this property and eight of them suppressed the growth of phage at concentrations less than one-tenth of those which affected the growth of the host, Ps. pyocyanea.

Extracts from 142 of the plants were tested against Influenza A virus in embryonated eggs and twelve of them suppressed virus multiplication. All extracts active against Influenza A virus were also active against the bacteriophage. Four extracts tested against Influenza A in mice were inactive. Eight extracts were investigated further; these were inactivated by proteins and were only active when in direct contact with the virus in protein-free media, Activity was closely associated with the tannin content of the extracts and could not be separated from it. Commercial tannins were also highly active in protein-free media.