Translator Disclaimer
1 May 2005 Time-resolved Microspectrofluorimetry and Fluorescence Lifetime Imaging of Hypericin in Human Retinal Pigment Epithelial Cells
Author Affiliations +
Abstract

Hypericin is the active ingredient of the off-the-shelf antidepressant St. John's Wort. It is an effective phototoxic agent and its systemic administration at therapeutic doses could induce particular damage in the eye due to continuous light exposure. Hypercin is strongly fluorescent and its fluorescence properties can be monitored to investigate noninvasively its localization and interactions. To this aim, time-resolved microspectrofluorimetry and fluorescence lifetime imaging were used to assess the spectral and temporal properties as well as the spatial distribution of the fluorescence emitted by retinal pigment epithelium (RPE) cells treated with Hyp at concentrations in the micromolar range (0.5–10 μM). In the presence of hypericin, the emission peaks at 600–605 nm and the fluorescence decay is best fitted with three lifetimes (5.5–7 ns, 1.9–2.5 ns and <0.8 ns). Spectral and temporal differences were observed between high (≥5 μM) and low hypericin concentrations. In particular, upon increasing concentration, the emission spectrum of the slow component broadens and its lifetime shortens. The latter change is observed also when high concentrations are reached locally, due to more efficient localization within the cell.

Paola Taroni, Gianluca Valentini, Daniela Comelli, Cosimo D'Andrea, Rinaldo Cubeddu, Dan-Ning Hu, and Joan E. Roberts "Time-resolved Microspectrofluorimetry and Fluorescence Lifetime Imaging of Hypericin in Human Retinal Pigment Epithelial Cells," Photochemistry and Photobiology 81(3), 524-528, (1 May 2005). https://doi.org/10.1562/2004-11-30-IR-385.1
Received: 30 November 2004; Accepted: 1 December 2004; Published: 1 May 2005
JOURNAL ARTICLE
5 PAGES

This article is only available to subscribers.
It is not available for individual sale.
+ SAVE TO MY LIBRARY

SHARE
ARTICLE IMPACT
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top