NCIt definition : The hexyl ester of 5-aminolevulinic acid (ALA) with photodynamic properties. As a
precursor of photoactive porphorins, hexyl 5-aminolevulinate induces the endogenous
production of the photosensitizer protoporphyrin IX (PPIX) which accumulates selectively
in tumor tissue. When exposed to specific wavelengths of light, PPIX is activated
and, depending on the wavelength and/or intensity of light, either fluoresces, thereby
allowing tumor imaging, or induces tumor cell apoptosis.;
Alternative definition : NCI-GLOSS: A substance that is used to find and kill tumor cells. It enters tumor
cells and becomes activated when exposed to a special type of light. A chemical reaction
causes the cells to produce fluorescent light and die.;