I . Preparations of bound nicotinic acid obtained from wheat bran by an acid extraction procedure (' niacytin preparations') were resolved into several nicotinic acid-containing components.2. Extraction of wheat bran under neutral conditions yielded 62 % of the bound nicotinic acid in solution; of this 90 : / o was non-diffusible. Methods were developed which gave high yields of ' non-diffusible nicotinic acid' preparations.3. The bound nicotinic acid in the latter preparation was linked to macromolecules of mol. wt about 1500 to 17000 daltons, approximately 60% of which were polysaccharide and 40 % peptide or glycopeptide in character.4. o-Aminophenol, and ferulic and sinapic acids, are also contained in macromolecules in wheat bran, but are not directly associated with the bound nicotinic acid.5. The significance of these results in explaining the nutritional unavailability of bound nicotinic acid is discussed.The association of nicotinic acid deficiency (pellagra) in man with cereal diets is related to the occurrence of the nicotinic acid in cereals in a bound and nutritionally unavailabIe form (Kodicek, 1962). The metabolic fate of bound nicotinic acid has been accounted for in the nicotinic acid-deficient rat (Mason & Kodicek, 1970a, b). The other questions to be answered regarding the nutritional unavailability of bound nicotinic acid concern its chemical structure. This report describes the types of macromolecules in which the bound nicotinic acid of wheat bran is contained.The nature of the bound nicotinic acid of cereal grains has been studied for over 30 years, since Kodicek (194oa, b) found that the nicotinic acid of wheat bran and maize required hydrolysis before it could be extracted. Essentially, there are two views: one is that the nicotinic acid is contained in a polysaccharide (Kodicek & Wilson, 1960) and the other that it is attached to a peptide (Das & Guha, 1960). Chaudhuri & Kodicek (1950) first obtained a preparation containing 28 mg nicotinic acid/g, and their method was developed by Kodicek & Wilson (1960) to give a preparation containing 50 mg nicotinic acid/g. This sample, which contained 20 mg protein/g attributed to an impurity, behaved as a single substance on Tiselius electrophoresis and counter-current distribution and was called ' niacytin ' ; it was suggested that the nicotinic acid was linked to a polysaccharide chain which was further substituted to a marked extent. On the other hand, Guha and co-workers obtained preparations from rice bran (Guha & Das, 1957) and from wheat bran and maize (Das & Guha, 1960) which contained 10 mg/g nicotinic acid ; these preparations contained protein and it was therefore concluded that the bound nicotinic acid was attached to protein. It was claimed that these preparations, which were called ' niacinogens', were crystalline, The experiments reported here were designed to determine whether the bound nicotinic acid of wheat bran was containcd in a single substance or in a number of substances, whether these substances were peptide, polysacchari...

trans-2-Acetamidocyclohexanol (1; n = 2, R = CH,) on addition to thionyl chloride in chloroform at 0" was converted rapidly and quantitatively to D,L-2-methyl-4,5-cis-cyclohexanooxazoline hydrochloride (2; n = 2, R = CH,) judging from shifts in the methyl proton resonances of the n.m.r. spectra of the amide and the reaction solution. The intermediate chlorosulfinate was estimated to have a half-life of less than 2.25 min. The oxazoline salt was isolated in 98% yield by sublimation of the crude product in vacuo and was identified by its i.r. and n.m.r. spectra and by its facile and almost quantitative hydrolysis to cis-2-aminocyclohexanol hydrochloride. The oxazoline salts 2 (n = 1, R = CH3, C6H4-pN02 and n = 2, R = C6H5, C6H4-pNO2) were readily obtained in 95% yield or better by the same general method and it was shown that the trans-2-acetamidocyclanols are the preferred starting materials for conversion to cis-2-aminocyclanol derivatives by the thionyl chloride inversion reaction. The oxazoline bases 4 (n = 1, R = CH,, C6H4-pN02 and n = 2, R = CH,, C6H4-pNO2) were readily obtained in high yield from the corresponding salts and differences in the i.r. and n.m.r. spectral characteristics of the salts and bases are reported.La D,L-mtthyl-2 cyclohexano-4,5-cis oxazoline (2; n = 2, R = CH3) est rapidement et quantitativement produite en ajoutant le chlorure de thionyle & 0 "C A I'acttamido-2 cyclohexanol-tram (1; n = 2, R = CH,) dans du chloroforme. On estime que le demi temps de vie du chlorosulfinate intermtdiaire est moins que 2.25 min. Ce rtsultat est mis en Bvidence par un glissement dans le signal des protons du groupement mtthyle dans les spectres r.m.n., de I'amide et de la solution rtactionnelle. Le chlorhydrate de I'oxazoline est isolt avec un rendement de 98% par la sublimation sous vide du psoduit brut. On a Btabli la structure du compod en se servant de donntes obtenues par spectroscopie i.r. et r.m.n. et on I'a vkrifite par une mtthode d'hydrolyse simple qui conduit avec un rendement pratiquement quantitatif au chlorhydrate de I'amino-2 cyclohexanol-cis. On obtient facilement les chlorohydrates des oxazolines 2 (n = 1, R = CH,, C6H4-pNO2 et n = 2, R = C6H,, C6H4-pNO2) avec des rendements d'au moins 95% en utilisant la mkme mtthode gCntrale et on a ddmontrt que les acttamido-2 cyclanols-trans sont les produits de dtpart les plus utiles pour obtenir les dBrivts d'aminocyclanol-2-cis par la rtaction d'inversion & l'aide du chlorure de thionyle. On obtient facilement les bases oxazolines 4 (n = 1, R = CH,, C6H4-pNO2 et n = 2, R = CH3, C6H4-pN02) avec de bons rendements & partir des sels correspondants et on dkrit des diffkrences dans les spectres r.m.n. et i.r. des sels et des bases.

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