title: Glycoside esters of 5-aminolevulinic acid for photodynamic therapy of cancer.
abstract: Aliphatic and ethylene glycol esters of 5-aminolevulinic acid (ALA) are very efficient precursors of the photosensitizer protoporphyrin IX (PpIX) for photodynamic therapy; however, they diffuse passively across the cell membrane and thus lack cell selectivity. We evaluated whether alpha-glucose, alpha-mannose, or beta-galactose esters of ALA would present improved properties as precursors of PpIX. Esterification was performed either at the position O-1 or O-6 of the sugars with or without an ethylene glycol linker, and these glycoside esters of ALA were evaluated in human cells. The results demonstrated that glycoside esters of ALA are efficient precursors of PpIX in human cancer and angiogenic endothelial cells, comparable to free ALA, but not in normal human fibroblasts. PpIX production was confirmed by fluorescence microscopy and photodynamic treatment of cells. The O-1 or O-6 positions of functionalization and the nature of the sugar moiety did not influence PpIX production. The presence of the ethylene glycol linker generally resulted in decreased PpIX production. The uptake of these glycoside esters of ALA by cells was not decreased in the presence of high concentrations of the related sugars. Inhibitors of alpha-glucosidases or alpha-mannosidases did not decrease PpIX production. These results suggest the involvement of active non-glycoside-specific membrane transporter(s) for uptake and of esterases rather than glycosidases in the release of ALA from the glycoside esters of ALA.
authors.affiliation: Institute of Chemistry, Neuchâtel University, avenue de Bellevaux, P.O. Box 2, CH-2007 Neuchâtel, Switzerland.
authors.forename: Ramakrishnan
authors.initials: R
authors.lastname: Vallinayagam
authors.forename: Frédéric
authors.initials: F
authors.lastname: Schmitt
authors.forename: Jérome
authors.initials: J
authors.lastname: Barge
authors.forename: Georges
authors.initials: G
authors.lastname: Wagnieres
authors.forename: Virginie
authors.initials: V
authors.lastname: Wenger
authors.forename: Reinhard
authors.initials: R
authors.lastname: Neier
authors.forename: Lucienne
authors.initials: L
authors.lastname: Juillerat-Jeanneret
mesh_terms: D000622:Aminolevulinic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use*; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004950:Esterases / Q000378:metabolism; D004951:Esterification; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism; D006027:Glycosides / Q000737:chemistry*; D006801:Humans; D009369:Neoplasms / Q000188:drug therapy*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000378:metabolism / Q000494:pharmacology; D011355:Prodrugs / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use; D011524:Protoporphyrins / Q000378:metabolism / Q000494:pharmacology; D012680:Sensitivity and Specificity
chemical_list: D006027:Glycosides; D017319:Photosensitizing Agents; D011355:Prodrugs; D011524:Protoporphyrins; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX; D004950:Esterases; D006026:Glycoside Hydrolases