Extracts from St John's wort and their antimicrobial activity

Abstract

In an effort to carry out a more in-depth investigation on the antimicrobial properties of H. perforatum, we have assayed different extracts (MeOH; petroleum ether; CHCl(3) and EtOAc) from the aerial parts of the plant against selected microorganisms. Growth inhibition was observed only for Gram-positive bacteria, B. subtilis and B. cereus being the most susceptible to the tested drugs. The Hypericum extract obtained with EtOAc was the most active. The main constituents of this extract, as determined by HPLC analysis, were flavonoids, hypericins and hyperforins. Incubation of the selected microorganisms with the pure chemicals resulted in a significant inhibition of their growth by hypericin, hyperforin and its stable dicyclohexilammonium salt. Flavonoids appeared inactive at all.

Antimicrobial efficacies of plant extracts and sodium nitrite against Clostridium botulinum

“…On the other hand, Al-Khayat and Blank (1985) reported the antimicrobial action of aqueous clove extract against Bacillus subtilis. Avato, Raffo, Guglielmi, Vitali, & Rosato, 2004) reported that the ethyl acetate extract of St. John's Wort that contained hypericin and hyperforin had inhibitory effects on Bacillus cereus and B. subtilis.…”

Hypericum sp.: essential oil composition and biological activities

“…Results of those studies have revealed that extract of Hypericum exert several pharmacological properties including antidepressant, antimicrobial and wound healing effects (Ishiguro et al 1990;Decosterd et al 1991;Jayasuriyab et al 1991;Rocha et al 1995;Ö ztürk et al 1996;Sokmen et al 1999;Daudt et al 2000;Mukherjee et al 2000;Pistelli et al 2000;Avato et al 2004). …”

Hypericin- and mTHPC-mediated photodynamic therapy for the treatment of cariogenic bacteria

“…It is currently among the most popular drugs against mild depression in complementary medicine. In addition to its potent photo-damaging effects on cancer cells [26], several studies indicated that HYP is active against various Gram-positive bacteria [27][28][29].…”