Diagnostic significance of urinary thiodiglycolic acid as a possible tool for studying the role of vitamins B12 and folates in the metabolism of thiolic substances

Abstract

We have found that the determination of thiodiglycolic acid (TDGA) in urine may help to characterize metabolic imbalance of substances participating in methionine synthesis, which leads to hyperhomocystinuria. From the metabolic scheme, based on a proper combination of known facts, we attempted to theoretically explain and to demonstrate the possibilities of TDGA formation via different ways of homocysteine transformation. This scheme was used in evaluating the results obtained by testing urine of a woman suffering from impaired function of methionine synthase reductase (CblE type of homocystinuria). The amount of TDGA excreted in her morning urine was very sensitive to the changes in her treatment based upon a combination of N5-formyl tetrahydrofolate, betaine and vitamin B12. Vitamin B12 given in the evening either alone or together with betaine increased the TDGA excretion in the morning urine up to ten times. On the other hand, in the absence of vitamin B12, betaine in combination with N5-formyl tetrahydrofolate hindered the appearance of TDGA in the morning urine. Generally, the determination of TDGA in urine of an appropriately pretreated patient may indicate the degree of success of the treatment.

Voltammetric determination of TBHQ at a glassy carbon electrode surface activated by in situ chemical oxidation

“…According to the recommendations of international organizations, the usage of synthetic antioxidants is regulated by legal authorities in a limited number of food items, with maximum limits in each case or association, 11 so it' is essential to develop an analytical method for monitoring the excessive use of permitted antioxidants and their degenerative products. Analytical methods for determining TBHQ, generally used in oil and food samples, have been widely reported over the past few decades, [12][13][14][15][16][17] such as highperformance liquid chromatography (HPLC), [18][19][20][21] gas chromatography (GC), [22][23][24] capillary electrophoresis, micellar electrokinetic capillary chromatography [25][26][27] and fourier transform infrared (FTIR) spectroscopy. 28 However, the instruments that were used in these methods are quite expensive or require a rather complicated preparation of the sample prior to the analysis and inappropriateness for eld use.…”