| 摘要 |
A high-molecular-weight substance extracted from the root of edible burdock, characterized in that (1) said substance is soluble in water and alkaline aqueous solutions, (2) said substance is adsorbable to an anion exchange cellulose but not adsorbable to a cation exchange cellulose, (3) said substance has an absorption wavelength peak within a range of 280 nm to 300 nm, and (4) said substance has a desmutagenicity such that when the number of revertant colonies from Salmonella TA98 is determined by using 2-nitro-p-phenylenediamine as a mutagen in accordance with the inhibitory effect test described in the specification, the concentration of the high-molecular-weight substance at which the desmutagenic rate (%) becomes 50% is 4 to 6 parts by weight per part by weight of the 2-nitro-p-phenylenediamine. The high-molecular-weight substance may be prepared by a process which comprises the steps of: (a) centrifuging the juice of burdock to remove foreign materials therefrom, (b) mixing the resulting supernatant with a phosphate buffer having a concentration of 1 to 2 moles and a pH of about 6.5 to about 7.5, salting out the mixture with a water-soluble alkali metal or ammonium salt of an inorganic acid, and thereafter collecting the precipitate, (c) dissolving the precipitate in a phosphate buffer having a concentration of about 10 to about 400 mM and a pH of about 6.5 to about 7.5, and dialyzing the resulting solution, and (d) ultrafiltering the dialyzate and withdrawing the concentrate and as required, lyophilizing the concentrate to yield a powder. The high-molecular-weight substance is useful for preventing the induction of mutation in an animal by a mutagen.
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