Hyperforin antimicrobial effects

St. John s wort has been used topically for wound healing for hundreds of years. Antibacterial properties have been reported as early as 1959, with hyperforin found to be the active component. Using multiple concentrations, it was discovered that no hyperforin dilutions had antimicrobial effects on Gram-negative bacteria or Candida albicans. There was, however, growth inhibition for all of the Gram-positive bacteria tested, some with the lowest dilution concentration of 0.1 pg/mL. Hyperforin was also shown to be effective at inhibiting methacillin-resistant Staphylococcus aureus (25). 

Historically, H. perforatum is a well known traditional remedy against infected wounds and skin lesions, and this effect is in part attributed to the antimicrobial activity of the drug. In a recent investigation on the antimicrobial effect of St. John s Wort [96,97], it was demonstrated that hypericin should also be regarded as an active antibiotic ingredient of H. perforatum extracts. Comparison of inhibitory activities showed that, in general, hypericin had lower minimum inhibitory concentrations - MICs (12.5 y) than hyperforin. 

Another common plant that appears to have some activity against MRSA is Hypericum perforatum L., commonly known as St. John s wort. In traditional folk medicine, oily extracts of St. John s wort are used for topical treatment of wounds, bums and myalgia [39]. The lipophilic phloroglucin-derivative hyperforin. Fig. 3, has antibacterial effects and has been shown to inhibit the growth of MRSA at a concentration of 1 (ig/ml [39]. Thus, investigating known plants based on their historical medical (ethnomedical) use is a potentially useful means of discovering new alternative antimicrobial agents. 

Important antimicrobial activity is also described for phloroglucinol derivatives other than hyperforin. Thus, some of the phloroglucinols isolated from H. japonicum [55] have been assayed against Gram-positive bacteria and found to be particularly effective against S. aureus. The presence of a benzoyl group on the filicinic acid moiety, typical of their structure, seems to be essential for their bioactivity. 

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