Comparison of antibacterial activity of hypericin activated bylight with hypericin not exposed to light

Background and Aim : Hypericin, a phenanthropeylene quinine pigment naturally occurring inHypericum perforatum L., possesses a variety of therapeutic activity such as antidepressant,antiviral, antibacterial and anticancer. Hypericin is well-known as a potent natural photosensitizingagent in photodynamic therapy.The present study aimed to evaluate the antibacterial activity ofHypericin in the light and in the dark on bacteria of clinical importance.Methods : The antibacterial activity of hypericin was tested against Staphylococcus aureus ATCC۶۵۳۸ and Escherichia coli ATCC ۸۷۳۹ in the presence of light (۵۹۰ nm, ۱۰ J/cm۲) and or in thedark using agar-well diffusion method and expressed as the average diameter of the zone ofinhibition of bacterial growth around the wells.Results : After light irradiation, the antibacterial activity for Staphylococcus aureus obtained atconcentration ۰. ۰۳ mg/mL, ۰.۰۵ mg/mL and ۰.۱ mg/mL with inhibition diameter values ۱۰.۵, ۱۱.۵and ۱۴.۰ mm, while in the dark, the inhibition-zone diameters were ۱۰.۰, ۱۱.۵ and ۱۳, respectively.The antibacterial activity of Escherichia coli both in the presence of light and in the dark wasslightly less than that of Staphylococcus aureus, so that the inhibition zone of mean diameters werein the range of ۹-۱۳ mmConclusion : The results of this study showed that there is no significant difference between lightactivatedor inactive hypericin in terms of antibacterial activity, and Staphylococcus aureus is moresensitive to hypericin than Escherichia coli.

کلیدواژه ها:

Antibacterial effect ، photodynamic therapy ، Hypericin ، Escherichia coli ، Staphylococcus aureus