Evaluation of the Light-Sensitive Cytotoxicity of Hypericum perforatum Extracts, Fractions, and Pure Compounds

Hypericum perforatum (Hp) is known for possessing antidepressant and antiviral activities. Despite its use as an alternative to conventional antidepressants, the identification of the cytotoxic chemicals derived from this herb is incomplete. In this study, the cytotoxicity of Hp extracts prepared in solvents ranging in polarity, fractions of one extract, and purified compounds were examined in three cell lines. All extracts exhibited significant cytotoxicity; those prepared in ethanol (no hyperforin, 3.6 μM hypericin, and 134.6 μM flavonoids) showed between 7.7 and 77.4% cell survival (p < 0.0001 and 0.01), whereas the chloroform and hexane extracts (hyperforin, hypericin, and flavonoids not detected) showed approximately 9.0 (p < 0.0001) and 4.0% (p < 0.0001) survival. Light-sensitive toxicity was observed primarily with the ethanol extracts sequentially extracted following removal of material extracted in either chloroform or hexane. The absence of light-sensitive toxicity with the Hp extracts suggests that the hypericins were not playing a prominent role in the toxicity of the extracts.

Keywords: Hypericum perforatum; St. John's wort; phototoxicity; cytotoxicity; hypericin; pseudohypericin; rutin; quercetin; quercitrin; isoquercitrin; hyperoside; chlorogenic acid; 8-isoprostane