Antimicrobial activity of Helichrysum plicatum DC.

Dry flower heads of Helichrysum plicatum were characterized by HPLC-DAD and a detailed antimicrobial assay of its ethanol extract was performed. Identification of phenolic com­pounds indicated the presence of apigenin, naringenin and kaempferol as free aglycones, glycosides of apigenin, naringenin, quercetin and kaempferol as well as chlorogenic acid and chalcone derivate. Antimicrobial activity of the extract was evaluated against various bacteria and fungi as well as yeast Candida albicans using microdilution method. Gram-positive bacteria were more sensitive to the tested extract ( MIC values were to 0.02 mg/mL) than Gram-negative bacteria (the greatest MIC was 0.055 mg/mL). Regarding pathogenic fungi, our tests demonstrated that fungi were more sensitive to the tested ext­ract than bacteria. The growth of the majority of the tested fungi was inhibited by concen­tration of 0.005 mg/mL. Moreover, the extract was significantly more active than com­mercial fungicide, fluconazole. The results of our tests indicate that the extract of H. plica­tum has significant antimicrobial activity and may find application in the pharmaceutical and food industry and organic agriculture.