Polyphenols from Bulgarian medicinal plants with anti-infectious activity

Three Bulgarian medicinal plants--Geranium macrorrhizum L. and G. sanguineum L. (Geraniaceae), and Epilobium hirsutum L. (Onagraceae) were analyzed phytochemically. Different polyphenols like flavonoids and tannis have been found to be principal constituents of the plants. A series of water or alcohol extracts was obtained, and their anti-infectious activity was tested. A significant inhibitory effect of water-alcohol extract and of four fractions from the polyphenolic mixture of E. hirsutum on the reproduction of influenza viruses in vitro, in ovo, and in vivo was established. Four extracts from G. macrorrhizum and three extracts from G. sanguineum were studied for in vitro inhibition of the growth of some Gram-negative bacteria (Klebsiella pneumoniae, Proteus vulgaris, Escherichia coli, Pseudomonas aeruginosa), Gram-positive bacterium (Staphylococcus aureus), and fungus (Candida albicans). Some geranium extracts caused a strong increase of the survival rate in an infection with K. pneumoniae in mice. Augmentation of the nonspecific host resistance in relation to the influence of the extracts on the classical complement activation pathway was also studied.