First preclinical evaluation of mono-[123I]iodohypericin as a necrosis-avid tracer agent.
OBJECTIVE
We have labelled hypericin, a polyphenolic polycyclic quinone found in St. John's wort (Hypericum perforatum), with( 123)I and evaluated mono-[(123)I]iodohypericin (MIH) as a potential necrosis-avid diagnostic tracer agent.


METHODS
MIH was prepared by an electrophilic radioiodination method. The new tracer agent was evaluated in animal models of liver infarction in the rat and heart infarction in the rabbit using single-photon emission computed tomography (SPECT), triphenyltetrazolium chloride (TTC) histochemical staining, serial sectional autoradiography and microscopy, and radioactivity counting techniques.


RESULTS
Using in vivo SPECT imaging, hepatic and cardiac infarctions were persistently visualised as well-defined hot spots over 48 h. Preferential uptake of the tracer agent in necrotic tissue was confirmed by perfect match of images from post-mortem TTC staining, autoradiography (ARX) and histology. Radioactivity concentration in infarcted tissues was over 10 times (liver; 3.51% ID/g in necrotic tissue vs 0.38% ID/g in normal tissue at 60 h p.i.) and over 6 times (myocardium; 0.36% ID/g in necrotic tissue vs 0.054% ID/g in normal tissue; ratios up to 18 for selected parts on ARX images) higher than in normal tissues.


CONCLUSIONS
The results suggest that hypericin derivatives may serve as powerful necrosis-avid diagnostic agents for assessment of tissue viability.
Ni
Yicheng
Y
Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium.
Huyghe
Dieter
D
Verbeke
Kristin
K
de Witte
Peter A
PA
Nuyts
Johan
J
Mortelmans
Luc
L
Chen
Feng
F
Marchal
Guy
G
Verbruggen
Alfons M
AM
Bormans
Guy M
GM
D000818:Animals; D000873:Anthracenes; D004353:Drug Evaluation, Preclinical; D006321:Heart / Q000000981:diagnostic imaging*; D008099:Liver / Q000000981:diagnostic imaging* / Q000473:pathology*; D008657:Metabolic Clearance Rate; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000378:metabolism; D009206:Myocardium / Q000473:pathology*; D009336:Necrosis / Q000000981:diagnostic imaging; D010569:Perylene / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D010865:Pilot Projects; D011817:Rabbits; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution
D000873:Anthracenes; D019275:Radiopharmaceuticals; D010569:Perylene; C004965:hypericin