Riboflavin undergone phtotoderadation in the presence of niacinamide and 1-ascorbic acid.The potodegradation of 1-ascorbic acid in riboflavin-niacinamide-ascorbic acid solution was not significant.1-Tryptophan could stabilize the phtodegradation of riboflavin and 1-ascorbic acid presumably due to the efficient nonradial transition of light energy from the complex to solvent media. The rate of thermodegradation of 1-ascorbic acid was accelerated by riboflavin in the presence of niacinamide.It was postulated that riboflavin acted asoxidative catalyst inascorbic acid thermodegradation.Differential UV spectroscopy was carried out to elucidate the complicated vitamin-vitamin and vitamin-amino acid interactions in aqueous solution.The possible mechanisms were also proposed to the experimental findings. 眾所周知riboflavin能促進1-ascorbic acid之光分解，但本研究發現在Niacinamide之存在下，1-ascorbic acid並未受riboflavin之作用進行光分解，反而發生riboflavin之光分解。同時在加溫虐待條件下，1-ascorbic acid與niacinamide之分子複合體應該比單獨之1-ascorbic acid更為安定，但本研究發現，如果有riboflavin共存其間，反而促進1-ascorbic acid之熱分解。1-tryptophan能同時穩定riboflavin及1-ascorbic acid之光分解反應。針對這些新現象的發現，本研究利用示差紫外光譜分析，推斷在溶液中各成份間相互作用產生複合體之可能性，並對實驗結果提出解釋。Riboflavin-niacinamide-ascorbic acid在水溶液中形成之複合體，經由riboflavin分子吸收光能後因無適當之能量承接對象，造成riboflavin之自行分解。但在Tryptophan-riboflavin-ascorbic acid複合體中所吸收之光能可經由良好之無輻射遷移，將能量釋放於溶酶系，產生對光之穩定作用。在熱分解時，riboflavin在riboflavin-niacinamide-ascorbic acid中扮演氧化觸媒之角色，促進1-ascorbic acid之氧化分解。Tryptophan與ascorbic acid間無顯著之作用，至少在光譜分析上不見其相互作用，故Tryptophan-riboflavin-ascorbic acid複合體之形成，可能是經由riboflavin之架橋作用。在熱分解時，這種相互作用被高動能所破壞，對ascorbic acid之安定沒有顯著之效應。
