Akhtar M J, Khan M A, Ahmad I
Research and Development Laboratories, GlaxoWellcome Pakistan Ltd., Karachi.
J Pharm Biomed Anal. 2000 Nov;23(6):1039-44. doi: 10.1016/s0731-7085(00)00383-6.
A study of the photolysis of folic acid in aqueous solution by visible radiation in the presence of riboflavin has been made. The second-order rate constants for the bimolecular interaction of folic acid and riboflavin have been determined in the pH range 4.0-9.0. The rate pH profile shows a gradual increase in the rate up to pH 6.2 (pHmax) followed by a decrease up to pH 9.0, depending upon the susceptibility of ionic species involved in the interaction. The rate of photolysis varies from 0.50 x 10(3) M(-1) min(-1) (pH 9.0) and 0.63 x 10(3) M(-1) min(-1) (pH 4.0) to 3.0 x 10(3) M(-1) min(-1) (pH 6.2) in the pH range studied. A HPLC method has been used for the assay of folic acid and its photoproducts, pterine-6-carboxylic acid and p-aminobenzoyl-L-glutamic acid in the presence of riboflavin.
对核黄素存在下叶酸在水溶液中经可见光辐射的光解进行了研究。已测定了叶酸与核黄素双分子相互作用在pH值4.0 - 9.0范围内的二级速率常数。速率 - pH曲线表明，速率在pH值达到6.2（pH最大值）之前逐渐增加，随后在pH值达到9.0之前下降，这取决于相互作用中所涉及离子物种的敏感性。在所研究的pH范围内，光解速率从0.50×10³ M⁻¹ min⁻¹（pH 9.0）和0.63×10³ M⁻¹ min⁻¹（pH 4.0）变化到3.0×10³ M⁻¹ min⁻¹（pH 6.2）。已采用高效液相色谱法在核黄素存在的情况下测定叶酸及其光产物蝶呤 - 6 - 羧酸和对氨基苯甲酰 - L - 谷氨酸。
