Abstract
A simple, sensitive method has been developed for the detection of small amounts of labile naturally occurring flavins as well as photoproducts of decomposition of riboflavin in plants. Plant tissue is homogenized in water containing ammonium sulfate. After removal of solid materials the extract is passed through a column of a resorcinol-formaldehyde resin. After elution the flavins are, if necessary, absorbed on and eluted from a second column of talc. Finally, they are examined by thin-layer chromatography with detection by fluorescence. When an extract from one corn coleoptile (0.06 gm) and containing approximately 6 ng of flavin was treated in this way, it was found that the riboflavin could be detected easily even when one-tenth of the total sample was placed on a thin-layer plate. When riboflavin was added to centrifuged homogenates of plant tissues and passed through the two-column separation steps, excellent recoveries of the added riboflavin were obtained as estimated spectrophotometrically. The method could be applicable to a wide variety of biological materials other than plants. A wide range of plant materials was examined for the occurrence of free flavins. Riboflavin was present in all materials examined, but in varying amounts. It was the only yellow, fluorescent material detected in many species including corn, wheat, beets, carrots, Irish potato, and baker's yeast. Extracts of oats, on the other hand, contained a second free flavin, which is negatively charged at pH 4.1, and is apparently that previously described by Zenk (2). This flavin was investigated by photolysis, hydrolysis, and reaction with periodic acid, dithionite, and silver acetate. The results confirm that it is a derivative or riboflavin yielding riboflavin upon hydrolysis. Etiolated shoots of Job's tears contain two neutral yellow, fluorescent compounds of unknown structure, in addition to the riboflavin. Both are probably derivatives of riboflavin, but four yellow, fluorescent compounds found in sweet potatoes are probably not flavins.
Published Version
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