title: Coupling reactions of catechins with natural aldehydes and allyl alcohols and radical scavenging activities of the triglyceride-soluble products.
abstract: Hydrophobic catechin derivatives were produced by heating with natural aldehydes or allyl alcohols. (+)-Catechin or (-)-epigallocatechin-3-O-gallate was heated with trans-2-hexenal, citral, (+)-citronellal, geraniol, or phytol. Although each reaction generated complex mixtures of products, 11 compounds were isolated and characterized by spectroscopic methods. The unsaturated aldehydes were found to attach to the flavan A-ring. Besides C-C linkage between aldehyde and the C-8 and/or C-6 of the catechin A-ring, formation of ether linkages between unsaturated carbons of the aldehydes and phenolic hydroxyl groups was observed. The allyl alcohols, geraniol and phytols, reacted at the galloyl group as well as the A-ring. After partitioning between triglyceride and water, the lipid layer of the reaction products showed strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. In contrast, epigallocatechin-3-O-gallate was not transferred to the lipid layer.
authors.affiliation: Department of Natural Product Chemistry, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8521, Japan.
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Fudouji
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Toshitugu
authors.initials: T
authors.lastname: Taguri
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Matsuo
authors.forename: Isao
authors.initials: I
authors.lastname: Kouno
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D001713:Biphenyl Compounds; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry*; D016166:Free Radical Scavengers / Q000737:chemistry*; D006358:Hot Temperature; D010851:Picrates; D020005:Propanols / Q000737:chemistry*; D012995:Solubility; D014280:Triglycerides; D014867:Water
chemical_list: D000447:Aldehydes; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D010851:Picrates; D020005:Propanols; D014280:Triglycerides; D014867:Water; C006463:allyl alcohol; D002392:Catechin; C045651:epigallocatechin gallate; C004931:1,1-diphenyl-2-picrylhydrazyl