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A colorimetric method of determination of tocopherol based on the reducing properties of tocopherol towards ferric chloride is described. The ferrous salt which is formed in the reduction is determined colorimetrically with α: α'-dipyridyl (similar coloured complex salts are formed with α:α' dipiperidyl and by o-phenanthroline). Not only is this method much more rapid and simple than the Potentiometric titration with gold chloride, but it also allows of the determination of much smaller quantities of tocopherol. Although o-phenanthroline gives a somewhat deeper colour than dipyridyl with ferrous ions, we have found dipyridyl preferable because the depth of colour produced with o-phenanthroline is not directly proportional to the concentration of ferrous ions and tocopherol.

From the unsaponifiable matter of cod-liver oil a fraction has been isolated with strong inhibitory action upon the growth of Mycobacterium tuberculosis in vitro, using the fluid medium of Sauton with and without addition of serum albumin. The fraction was toxic to guinea pigs and therefore could not be studied effectively in experimental tuberculosis in these animals.

Fur die Herstellung des unverseifbaren Anteiles von Kabeljau-Lebertran wird eine neue chromatographische Methode beschrieben. Die Reinigung und die Abtrennung der aktivsten Fraktionen erfolgt mit Hilfe einer mikrobiologischen Methode. Die Aktivitat beschrankt sich auf die ungesattigten α-Glycerylather, und zwar wurden auser Selachylalkohol noch andere ungesattigte α-Glycerylather isoliert. Glycerylethers of Cod-Liveroil A new chromatographic method has been described for the manufacture of the unsaponifiable part of Cod-Liveroil. The purification and separation of the most active fractions succeed with the help of microbiological methods. The activity is confined to the unsaturated α-glycerylethers, and apart from selachyl-alcohol other unsaturated α-glycerylethers have been isolated.

In this communication a method for the estimation of tocopherol in blood-serum is described. The stability of tocopherol towards alkali and acid, and the saponification of acetyl-tocopherol have been investigated.

The author has investigated the influence of cholesterol on the reaction between dl-α-tocopherol and the ferric chloride-dipyridyl reagent. The influence of cholesterol as found by some investigators must have been caused by an impurity in the cholesterol.

In our first communication we have described a colorimetric determination of tocopherol and application of this determination to vitamin E concentrates. To investigate the tocopherol content of biological material it is necessary to remove interfering substances and thus we have investigated in this communication the separation of tocopherol from carotinoids and from vitamin A. The reaction of vitamin A with ferric chloride-dipyridyl and also the reaction velocity of tocopherol, carotene and vitamin A with the reagent have been studied.

In this communication the author describes a method for the seperation of lactoflavin and lactoflavin phosphate. Benzyl alcohol and other aromatic alcohols are used for this separation. The lactoflavin is rapidly extracted from aqueous solutions containing both components by the aromatic alcohol whereas only very small quantities of lactoflavin phosphate are extracted.

1. The unsaponifiable fraction of cod-liver oil contains substances which in a concentration of 2 μg per ml of Sauton's medium have a marked inhibitory action on the growth ofM. tuberculosis D328 and the virulent strain A30. 2. Saturated and unsaturateda-glycerylethers are very probably responsible for this activity. 3. Addition of blood serum albumin to the medium gives an important reduction of the growth inhibition by these substances. 4. With analogous fractions of margarine, butter, yolk and beef dripping growth inhibition could not be obtained. 5. The presence of dead Mycobacteria reduces the observed growth inhibition considerably. A quantitative relationship exists between the amount of dead bacteria added and the amount of inhibitor which is neutralised. It could be shown that the inhibitor is adsorbed by the added bacteria. Each bacterium binds 4×107 molecules. Supposing adsorption as a monomolecular layer, this means 1 molecule to about 20 A2 of the bacterial surface. 6. The glycerylether fraction of cod-liver oil (fraction 5) which inhibits in a concentration of 1 μg/ml of Sauton's medium the growth of virulent tubercle bacteria has no favourable action on tuberculosis in guinea-pigs in a daily dose of 25 mg given per os or by subcutaneous injection. Indeed the substance is toxic and oral administration to healthy guinea-pigs causes hyperaemia of the intestinal mesenterium, swollen mesenterial lymphglands and growth of connective tissue (sometimes followed by strangulation of the intestine).