|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1993 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1992 : ¥1,500,000 (Direct Cost : ¥1,500,000)
Callus tissue of Gingko biloba, which were originally derived from petiole, were cultured on MS agar medium containing NAA and kinetin in the dark. Three classes of calllus cultures were obtained after subculture and expressed as brown color(DB), middle brown color(MDB) and white color(DW) calli, respectively. These calli and leaves of mother tree were homogenized in 70% Me_2CO, filtered and concentrated. Ethyl acetate soluble fraction(Et-S layr) and insoluble fraction(Et-I layr) were obtained from the extract. Three peaks were detected in each of all Et-S layrs by HPLC and TLC, and relative retention time of these peaks were the respective same. The content of these peaks was the highest in the MDB.From a result of HPLC analyzes, two in the three peaks were identified as corresponding to catechin and gallo catechin. The quantities of these compounds (flavanol monomer) increased with an increase in browning of callus cultures. On the additional determination in medium of those Et-S layr fractions, callus cultured on medium containing Et-S layr fractoin of leaves was violent browning even if only a very few amount and the inhibition of growth occured. On the other hand, growth of callus cultured on medium containing Et-S layr fraction of DB were enhanced by the presence of a small amount of these fractions and inhibited by the presence of a large amount of these fractions. When callus cultured on medium containing commercial catechin 40 mg/1, it was found that browning phenomenon was accutually occured.
From this investigation, it has become apparent that flavanol and proanthocyanidines, considered as origin compounds of browning phenomenon, were possible to prevent the browning by the addition of small amounts and occured it at the large amounts of these compounds.