Hypericin has been studied as a novel natural photosensitizer for PDT. It has been extracted from plants (St.-John's-wort). Oral administration (10% alcohol solution in a dose 2 mg/kg b.w.) was applied for 15 patients with gastric cancers 18 - 48 h before surgery. Normal and cancerous tissue samples were resected and underwent fluorescence analysis 1 - 2 h after resection. Tissue fluorescence was excited by He-Cd (20 mW, 442 nm) and Ar laser beams (100 mW, 488 nm) and registered from 510 to 725 nm. In tissue hypericin has maximum fluorescence peak at 603 nm for both excitation wavelengths. Fluorescence intensity ratio I₆₀₃/I₅₀₃ chosen as a criterion for tissue classification was varied from 1.6 to 3.2 (mean 2.5) for adenocarcinoma under He-Cd excitation whereas Ar laser excitation gave from 2.5 up to 4.2 (mean 3.5). Normal tissue had this ratio from 0.48 to 0.65 (mean 0.55) and from 0.53 to 0.75 (mean 3.5) for He-Cd and Ar laser excitation, respectively. No side effects were observed in patients during 6 month follow-up.

Date Published: 2 April 1996
PDF: 8 pages
Proc. SPIE 2675, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy V, (2 April 1996); doi: 10.1117/12.237522

Published in SPIE Proceedings Vol. 2675:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy V
Thomas J. Dougherty, Editor(s)