title: In vitro cis-trans photoisomerization of palythene and usujirene. Implications on the in vivo transformation of mycosporine-like amino acids.
abstract: The in vitro photoinduced reactions of the mycosporine-like amino acids (MAA) usujirene and palythene were studied by monochromatic stationary irradiation at 366 nm. High-performance liquid chromatography analysis of the irradiated aqueous solution of usujirene indicated a low photoreactivity on the basis of the observed photodecomposition quantum yield of phi(-U) = (2.86 +/- 0.80) x 10(-5), which can be partially accounted for by the cis-trans photoisomerization of usujirene to palythene (phi(U-->P) = [1.71 +/- 0.13] x 10(-5)). However, palythene in aqueous solution showed a higher photostability than did usujirene under equivalent conditions, establishing a photostationary mixture of cis-trans isomers with a relative composition of palythene-usujirene (11:1). These results may explain the preferential in vivo accumulation of palythene relative to that of usujirene observed in several dinoflagellate species.
authors.affiliation: Departamento de Química, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina. ferconde@mdp.edu.ar
authors.forename: Federico R
authors.initials: FR
authors.lastname: Conde
authors.forename: Mario O
authors.initials: MO
authors.lastname: Carignan
authors.forename: M Sandra
authors.initials: MS
authors.lastname: Churio
authors.forename: José I
authors.initials: JI
authors.lastname: Carreto
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D007536:Isomerism; D010777:Photochemistry; D000461:Rhodophyta / Q000737:chemistry
chemical_list: D000596:Amino Acids