Excretion of conjugated 2-amino-3-hydroxyacetophenone by man, and its significance in tryptophan metabolism.

nine is excreted on giving tryptophan to rats with a simple thiamine deficiency. 3. It is therefore concluded that thiamine is concerned in the conversion of tryptophan into formylkynurenine. 4. Similar experiments combining biotin and pyridoxine deficiencies suggest that biotin is unlikely to be concerned in any stage in the conversion of tryptophan into hydroxykynurenine. 5. Considerable advantages were found in giving vitamins by stomach-tube rather than by mixing them in the diet. I thank Dr A. M. Copping for her advice, and Mr A. Asatoor and Miss R. Paul for skilled assistance.