The measure of sorbitol in serum can act as a good indicator in the monitoring of the diabetic complications. To analyze the sorbitol level in serum medium, fluorometric enzymatic assay was performed. To remove the excess sorbitol from the body, proposed binding of sorbitol with caffeine was investigated. Their interaction in serum medium was studied and established by UV-Vis, fluorescence spectrophotometry, and time-correlated single photon counting (TCSPC). The linear calibration of sorbitol (in the range 10–50 mM) was done using UV-Vis spectrophotometry. Time scan experiments furnished the reaction rate of sorbitol assayed solution as well as sorbitol–caffeine complex as 0.021 min⁻¹ and 0.018 min⁻¹, respectively. A sudden drop was observed in the fluorescence lifetime of reduced nicotinamide adenine dinucleotide (NADH) present in sorbitol assayed solution upon complexation with caffeine, that is, from 1.774 × 10⁻⁰⁹ to 1.23 × 10⁻¹⁰ Sec, which indicates the hindrance in the formation of NADH and the probable formation of some other species. Isothermal titration calorimetric experiments clearly indicate the number of binding sites (i.e., 3.89, 1.40, and 2.07) that exist between sorbitol and caffeine at the complexation ratio of 1:1.2, 1:1.5, and 1:3. The present method can be helpful in pharmacological and therapeutic studies of sorbitol using caffeine for treating diabetic neuropathy.

中文翻译：

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游离血清山梨糖醇及其与咖啡因的相互作用：糖尿病神经病变的合理补救方法

血清中山梨醇的测定可以作为监测糖尿病并发症的良好指标。为了分析血清培养基中的山梨糖醇水平，进行了荧光酶促测定。为了从体内去除多余的山梨糖醇，研究了山梨糖醇与咖啡因的结合。通过紫外-可见光、荧光分光光度法和时间相关单光子计数 (TCSPC) 研究并确定了它们在血清培养基中的相互作用。使用 UV-Vis 分光光度法对山梨糖醇（范围 10-50 mM）进行线性校准。时间扫描实验提供了山梨糖醇测定溶液以及山梨糖醇-咖啡因复合物的反应速率为 0.021 min ^-1和 0.018 min ^-1， 分别。在与咖啡因络合后，山梨糖醇测定溶液中存在的还原型烟酰胺腺嘌呤二核苷酸 (NADH) 的荧光寿命突然下降，即从 1.774 × 10 ^-09到 1.23 × 10 ^-10秒，这表明在NADH 的形成和一些其他物种的可能形成。等温滴定量热实验清楚地表明了以 1:1.2、1:1.5 和 1:3 的络合比存在于山梨糖醇和咖啡因之间的结合位点的数量（即 3.89、1.40 和 2.07）。本方法可有助于使用咖啡因治疗糖尿病神经病变的山梨糖醇的药理学和治疗研究。