Abstract
Photosensitizing properties of hypericin are well known, and the chicken
chorioallantoic membrane has previously been used to test photodynamic
effects of hypericin and other substances. In our study the photodynamic
effect of hypericin in the ex ovo quail chorioallantoic membrane
model was evaluated. Steady-state and time-resolved fluorescence
spectroscopy of hypericin solution in PEG-400 and its mixture in PBS was
performed to assess and characterize the process of aggregation and
disaggregation of hypericin during the drug formulation preparation. A
therapeutical formulation (2 µg/g of embryo weight) was topically applied on
CAM into the silicone ring. Hypericin was excited by diode laser with
wavelength 405 nm, fluence rate 140 mW/cm2, and fluence 16.8
J/cm2. Hypericin in 100 % PEG-400 exhibits typical
fluorescence spectra with a maximum of about 600 nm, while hypericin 10%
PEG-400 formulation exhibits almost no fluorescence. Time resolved spectra
analysis showed fluorescence decay of hypericin in 100 % PEG-400 solution
with a mean lifetime of 5.1 ns and in 10 % PEG 4.1 ns. Damage of quail
chorioallantoic membrane vasculature after photodynamic therapy ranged from
hemorrhage and vanishing of capillary vessels to thrombosis, lysis, and
hemorrhage of larger vessels.
The presented findings suggest that quail embryos can be used as a suitable
model to test the effect of hypericin and other photodynamic compounds.
Key words
hypericin - Japanese quail - chorioallantoic membrane - photodynamic therapy - aggregation -
Hypericum
- Hypericaceae