IntroductionArctiurn Lappa (Burdock) is a coarse biennial weed which proliferates in Europe, Asia and Sorth America.' The roots of this plant form a part of the vegetable portion of the Japanese dietary. The moist roots are sliced and cooked in fat.3 The authors4 have shown the carbohydrate to be absorbed and utilized by white rats as evidenced by increased glycogen storage in the liver. This fact was demonstrated also by showing that the root of hrctium Lappa exhibited a nitrogen-sparing action on dogs fed on a diet of protein.Its clinical value in the treatment of diabetes mellitus has been shown by one of us (J.K.) with Silver and Cohen.sThe authors have separated the polysaccharide (presumably) inulin from the root and have subjected it to a physicochemical study. The literature contains many references to the work on the inulin from dahlia and Jerusalem artichoke, but no reference was found to the properties of inulin from this source.Tanret6 investigated the physical and chemical properties of the inulin from Jerusalem artichoke and found the substance to consist of inulin, pseudo-inulin and inulenin. The value of the Jerusalem artichoke in the treatment of diabetes mellitus as evidenced by the classical experiments of Root and Baker' and also Carpenter and Root* stimulated a renewed interest in the properties of the carbohydrate from this root. Thus Irvine and Steeles, Drew and Haworthlo and also Haworth and Learner" have conducted recently extensive experiments on the structure of inulin from dahlia and the hydrolytic cleavage of this carbohydrate.Furthermore, Jackson et al." have studied the rate of hydrolysis of the artichoke inulin in their comprehensive investigations on the preparation of levulose.
In previous communications the authors (5,4) studied the influence of certain of the sugar alcohols and their anhydrides upon the dissociation constant of boric acid. In one study (4) it was demonstrated that erythritan, 1,4-anhydroerythritoI, was unique among the compounds investigated, inasmuch as its downward displacement of the titration curve of boric acid was greater than that of any other compound. This interesting property of erythritan prompted the present physicochemical investigation of the erythritan-boric acid complex.
MATERIALS AND METHODThe boric acid was of buffer quality. The erythritan was prepared from erythritol by dehydration with sulfuric acid (3,1). The calculated values for its composition are as follows: carbon, 46.15 per cent; hydrogen, 7.69 per cent. Analysis gave the following composition: carbon, 46.02 per cent; hydrogen, 7.58 per cent. The levulose employed was Merck's crystals.The pH was determined electrometrically at 24°C.±1°, using the Wilson-type (7) hydrogen electrode.
EFFECT OF ERYTHRITAN-BORIC ACID RATIO ON pHIn former studies the pH of a 4 per cent erythritan solution in onetenth molar boric acid was found to be 2.6. The following studies were instituted to determine the influence of varying concentrations of erythritan upon the pH of a solution of boric acid of fixed concentration. The results are set forth in figure 1, curve A.
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