Marker constituents of the natural antioxidant Eucalyptus leaf extract for the evaluation of food additives.
In order to establish the marker constituents of the natural antioxidant food-additive Eucalyptus leaf extract, the UV-absorbing constituents of two eucalyptus leaf extracts registered as food additives (eucalyptus A and B) were investigated. Several major peaks on the reversed-phase HPLC chromatogram of eucalyptus A were characterized as gallic acid, ellagic acid, 3-O-beta-D-glucuronides of quercetin and kaempferol, and a hydrolyzable tannin dimer, oenothein B, by direct comparison with authentic specimens isolated from Eucalyptus globulus leaves. A new gallotannin was found in the E. globulus leaf extract, and its structure was found to be 1,2,3,6-tetra-O-galloyl-beta-D-galactose. Two major peaks on the HPLC chromatogram of eucalyptus B were identified as gallic acid and ellagic acid, indicative of degradation products from hydrolyzable tannins in the leaves. Considering the evaluation of antioxidant activity by radical scavenging ability, a standardization of eucalyptus leaf extract, including the antioxidative polyphenol, oenothein B, is proposed.
College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime, Japan. amakura@cc.matsuyama-u.ac.jp
Yoshiaki
Y
Amakura
Morio
M
Yoshimura
Naoki
N
Sugimoto
Takeshi
T
Yamazaki
Takashi
T
Yoshida
D001688:Biological Products / Q000737:chemistry*; D015415:Biomarkers / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D005052:Eucalyptus / Q000737:chemistry*; D005503:Food Additives / Q000737:chemistry*; D016166:Free Radical Scavengers / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry*
D001688:Biological Products; D015415:Biomarkers; D005503:Food Additives; D016166:Free Radical Scavengers; D010936:Plant Extracts