Component analysis of propolis collected on Jeju Island, Korea.

A study of propolis from Jeju Island, located off the southern tip of Korea, led to the isolation and identification of eight chalcones: (±)-(E)-4'-methoxy-4,2'-dihydroxy-3'-(2″,3″-dihydroxy-3″-methylbutyl)-chalcone, (E,E,E)-4,2',4'-trihydroxy-3'-(7″-hydroxy-3″,7″-dimethyloct-2″,5″-dienyl)-chalcone, (±)-(E,E)-4,2',4'-trihydroxy-3'-(5″-hydroxy-3″,7″-dimethyloct-2″,6″-dienyl)-chalcone, (±)-(E)-4'-methoxy-4,3″,4″-trihydroxy-2″,2″-dimethyldihydropyrano-(2',3')-chalcone, (±)-(E)-4'-methoxy-4,3″-dihydroxy-2″-(1″'-hydroxyisopropyl)-dihydrofurano-(2',3')-chalcone, (-)-(E)-4,4'-dihydroxy-2″-(1″'-hydroxy-1″',5″'-dimethylhex-4″'-enyl)-dihydrofurano-(2',3')-chalcone, (+)-(E)-4,2'-dihydroxy-2″-methyl-2″-(3″',4″'-dihydroxy-4″'-methylpentanyl)-2H-pyrano-(3',4')-chalcone and (-)-(E)-4,2'-dihydroxy-2″-methyl-2″-(3″',4″'-dihydroxy-4″'-methylpentanyl)-2H-pyrano-(3',4')-chalcone. Nineteen other known compounds were also isolated. Their structures were determined by spectroscopic analyses and comparison with literature data. The propolis from Jeju Island contained compounds not present in propolis from other regions.