Coupling reactions of catechins with natural aldehydes and allyl alcohols and radical scavenging activities of the triglyceride-soluble products.
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.
Fudouji
Ryusuke
R
Department of Natural Product Chemistry, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8521, Japan.
Tanaka
Takashi
T
Taguri
Toshitugu
T
Matsuo
Yosuke
Y
Kouno
Isao
I
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
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