REACTIONS AND KINETICS OF BAICALIN WITH REDUCING SPECIES, H, E(SOLV)(-) AND GAMMA-HYDROXYETHYL RADICAL IN DEARERATED ETHANOL SOLUTION UNDER GAMMA-IRRADIATION

Baicalin(beta-D-Glucopyranosiduronic acid, 5,6-dihydroxy-oxo-2-phenyl-4H-1-benzopyran-7-yl) is a naturally occurring flavonoid of pharmacological importance and one of typical Chinese herbs. The gamma-radiolysis of baicalin in the deaerated liquid ethanol was studied. The G values of H2 and 2,3-butanediol decrease with increasing baicalin concentration indicates that baicalin is able to scavenge reducing species, H and alpha-hydroxyethyl radicals, efficiently. Two gamma-radiolytic products of baicalin-mono-hydroxyethyl and dihydroxyethyl derivatives-formed and were isolated; their structures are determined as well. A reasonable mechanism of gamma-radiolysis of baicalin is proposed as well as the relevant rate constants obtained. The rate constant of baicalin with alpha-hydroxethyl radicals is 3 x 10(4) mol-1.dm3.s-1, and that of H atoms with baicalin is 7 x 10(3) times as large as that with ethanol.Chemistry, PhysicalNuclear Science & TechnologyPhysics, Atomic, Molecular & ChemicalSCI(E)EI11ARTICLE2217-2224