Polymeric procyanidins as radical-scavenging components in red-hulled rice.
The extracts from white-, black-, and red-hulled rice were prepared by sequential extraction with six different polar solvents, and their radical-scavenging activities were measured by methods using 1,1-diphenyl-2-picrylhydrazyl radical (DPPH*) and tert-butyl hydroperoxyl radical (t-BuOO*). The extracts prepared with highly polar solvents, methanol and deionized water, exhibited higher DPPH* and t-BuOO* scavenging activities in all three cultivars. In addition, the acetone extract from red-hulled rice exhibited a high DPPH* and t-BuOO* scavenging activity, while no such activity was detected for the acetone extracts from white- and black-hulled rice. The major components responsible for the radical scavenging in the acetone extract from red-hulled rice were identified as procyanidins by acidic hydrolysis, vanillin assay, and Sephadex LH-20 chromatography. GPC analysis of the acetylated procyanidins revealed that the average molecular weight is about 5000, in a range of about 500-18,000.
Oki
Tomoyuki
T
National Agricultural Research Center for Kyushu Okinawa Region, National Agricultural Research Organization, 2421 Suya, Nishigoshi, Kikuchi, Kumamoto 861-1192, Japan.
Masuda
Mami
M
Kobayashi
Mio
M
Nishiba
Yoichi
Y
Furuta
Shu
S
Suda
Ikuo
I
Sato
Tetsuo
T
D000975:Antioxidants / Q000032:analysis; D044946:Biflavonoids; D001713:Biphenyl Compounds; D002392:Catechin / Q000032:analysis*; D005591:Chemical Fractionation; D002851:Chromatography, High Pressure Liquid; D003116:Color; D005511:Food Handling; D016166:Free Radical Scavengers / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008163:Luminescent Measurements; D012275:Oryza / Q000737:chemistry*; D010851:Picrates; D010936:Plant Extracts / Q000737:chemistry*; D044945:Proanthocyanidins; D012639:Seeds / Q000737:chemistry; D020122:tert-Butylhydroperoxide
D000975:Antioxidants; D044946:Biflavonoids; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D010851:Picrates; D010936:Plant Extracts; D044945:Proanthocyanidins; C017674:procyanidin; D002392:Catechin; D020122:tert-Butylhydroperoxide; C004931:1,1-diphenyl-2-picrylhydrazyl