title: Role of catechol structure in the adsorption and transformation reactions of L-DOPA in soils.
abstract: 3-(3',4'-Dihydroxyphenyl)-L-alanine (L-DOPA), which is synthesized in velvet bean (Mucuna pruriens), inhibits plant growth. The concentration of L-DOPA in soil is reduced by adsorption and transformation reactions, which can result in the reduction of its plant-growth-inhibitory activity. To determine which part of the L-DOPA structure is involved in the adsorption and soil transformation reactions, we compared the kinetics of L-DOPA disappearance in a volcanic ash soil with that of L-phenylalanine (3-phenyl-L-alanine) and L-tyrosine (3-(4'-hydroxyphenyl)-L-alanine), compounds that are similar in structure to L-DOPA but do not have a catechol (o-dihydroxybenzene) moiety. L-Phenylalanine and L-tyrosine were not adsorbed and transformed in the soil at equilibrium pH values between 4 and 7. These results suggest that the adsorption and transformation reactions of L-DOPA in the soil involve the catechol moiety and not the amino and carboxylic acid groups, which are common to all three compounds. Like L-DOPA, (+)-catechin, another allelochemical that contains a catechol moiety, underwent adsorption and soil transformation reactions. Thus, we concluded that the concentrations of allelochemicals bearing a catechol moiety in soils will decrease rapidly owing to adsorption and transformation reactions, and this decrease will be faster in soils with a high pH value or high adsorption ability. Owing to this decrease in concentration, allelopathic phenomena may not occur.
authors.affiliation: Biodiversity Division, National Institute for Agro-Environmental Sciences (NIAES), 3-1-3 Kan-nondai, Tsukuba, Ibaraki, 305-8604, Japan. furuba@affrc.go.jp
authors.forename: Akihiro
authors.initials: A
authors.lastname: Furubayashi
authors.forename: Syuntaro
authors.initials: S
authors.lastname: Hiradate
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Fujii
mesh_terms: D000327:Adsorption; D002392:Catechin / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D002396:Catechols / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D018545:Lactuca / Q000187:drug effects / Q000254:growth & development; D007980:Levodopa / Q000737:chemistry* / Q000378:metabolism*; D031299:Mucuna / Q000737:chemistry / Q000378:metabolism; D010649:Phenylalanine / Q000737:chemistry / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology; D012987:Soil; D013329:Structure-Activity Relationship; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism; D018707:Volcanic Eruptions
chemical_list: D002396:Catechols; D010937:Plant Growth Regulators; D012987:Soil; D014443:Tyrosine; D007980:Levodopa; D010649:Phenylalanine; D002392:Catechin; C034221:catechol