title: New photoremovable protecting groups for carboxylic acids with high photolytic efficiencies at near-UV irradiation. Application to the photocontrolled release of L-glutamate.
abstract: We report here the syntheses and the photolytic properties of 3-(4,5-dimethoxy-2-nitrophenyl)-2-butyl (DMNPB) esters as new photoremovable groups for carboxylic acids, and their use for the caging of L-glutamate. A high-yielding synthesis of the DMNPB esters led to a 4:1 threo/erythro diastereomeric mixture, which could be separated by HPLC. While these esters were stable in neutral buffer, photolysis at 364 nm induced a > or =95 % release of the carboxylic acid, with a 0.26 quantum yield for L-glutamate formation. L-Glutamate release was also possible by two-photon photolysis with an action cross section of 0.17 GM at 720 nm. Laser photolysis at 350 nm generated a transient species at around 410 nm, attributed to a quinonoid aci-nitro intermediate that decayed in the submillisecond time range (t(1/2)=0.53 ms) for the faster gamma-L-glutamyl threo-esters. Given the absorbance of these esters (lambda(max)=350 nm; epsilon=4500), the threo DMNPB esters represent new caging groups that can be efficiently photolyzed at near-UV wavelengths. An efficient and rapid photolytic release of L-glutamate has been demonstrated on hippocampal neurons in primary culture.
authors.affiliation: Laboratoire de Chimie Bioorganique-UMR 7175 LC1 CNRS, Faculté de Pharmacie, Université Louis Pasteur Strasbourg, B. P 24, 67401 Illkirch Cedex, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Specht
authors.forename: Jean-Sébastien
authors.initials: JS
authors.lastname: Thomann
authors.forename: Karine
authors.initials: K
authors.lastname: Alarcon
authors.forename: Weerawut
authors.initials: W
authors.lastname: Wittayanan
authors.forename: David
authors.initials: D
authors.lastname: Ogden
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Furuta
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kurakawa
authors.forename: Maurice
authors.initials: M
authors.lastname: Goeldner
mesh_terms: D002021:Buffers; D002264:Carboxylic Acids / Q000737:chemistry*; D002478:Cells, Cultured; D004952:Esters / Q000737:chemistry; D005971:Glutamates / Q000737:chemistry* / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects; D015394:Molecular Structure; D010782:Photolysis; D013237:Stereoisomerism; D014466:Ultraviolet Rays
chemical_list: D002021:Buffers; D002264:Carboxylic Acids; D004952:Esters; D005971:Glutamates