Phenolic content, antimicrobial and antioxidant activities of Hypericum perfoliatum L.

Phenolic composition of three extracts of Hypericum perfoliatum was investigated; moreover also their antimicrobial and antioxidant activities were evaluated. The chloroform-methanol and methanol extracts showed antioxidant activity (IC50 less than 35 μg/mL), probably due to the presence of flavonoids, namely hyperoside (1.6 mg/mL in both extracts) and phenolic acids, such as chlorogenic acid (0.4 and 0.5 mg/mL, respectively). On the contrary, chloroform extract did not show remarkable antioxidant activity. Chloroform and chloroform-methanol extracts exhibited antimicrobial activity against the Gram positive Bacillus cereus (strains DSM 4313 and DSM 4384) and S. aureus and the Gram negative Escherichia coli and Pseudomonas aeruginosa strains, as well as against the emergent pathogen Chronobacter sakazakii.