Phototoxicity in human retinal pigment epithelial cells promoted by hypericin, a component of St. John's wort.

Published

Journal Article

St. John's wort (SJW), an over-the-counter antidepressant, contains hypericin, which absorbs light in the UV and visible ranges. In vivo studies have determined that hypericin is phototoxic to skin and our previous in vitro studies with lens tissues have determined that it is potentially phototoxic to the human lens. To determine if hypericin might also be phototoxic to the human retina, we exposed human retinal pigment epithelial (hRPE) cells to 10(-7) to 10(-5) M hypericin. Fluorescence emission detected from the cells (lambda(ex) = 488 nm; lambda(em) = 505 nm) confirmed hypericin uptake by human RPE. Neither hypericin exposure alone nor visible light exposure alone reduced cell viability. However when irradiated with 0.7 J cm(-2) of visible light (lambda > 400 nm) there was loss of cell viability as measured by MTS and lactate dehydrogenase assays. The presence of hypericin in irradiated hRPE cells significantly changed the redox equilibrium of glutathione and a decrease in the activity of glutathione reductase. Increased lipid peroxidation as measured by the thiobarbituric acid reactive substances assay correlated to hypericin concentration in hRPE cells and visible light radiation. Thus, ingested SJW is potentially phototoxic to the retina and could contribute to retinal or early macular degeneration.

Full Text

Duke Authors

Cited Authors

  • Wielgus, AR; Chignell, CF; Miller, DS; Van Houten, B; Meyer, J; Hu, D-N; Roberts, JE

Published Date

  • May 2007

Published In

Volume / Issue

  • 83 / 3

Start / End Page

  • 706 - 713

PubMed ID

  • 17576381

Pubmed Central ID

  • 17576381

Electronic International Standard Serial Number (EISSN)

  • 1751-1097

International Standard Serial Number (ISSN)

  • 0031-8655

Digital Object Identifier (DOI)

  • 10.1562/2006-08-09-RA-1001

Language

  • eng