Novel Spectrophotometric Method for the Quantitation of Urinary Xanthurenic Acid and Its Application in Identifying Individuals with Hyperhomocysteinemia Associated with Vitamin B6 Deficiency

الملخص EN

A novel spectrophotometric method for the quantification of urinary xanthurenic acid (XA) is described.

The direct acid ferric reduction (DAFR) procedure was used to quantify XA after it was purified by a solid-phase extraction column.

The linearity of proposed method extends from 2.5 to 100.0 mg/L.

The method is precise, yielding day-to-day CVs for two pooled controls of 3.5% and 4.6%, respectively.

Correlation studies with an established HPLC method and a fluorometric procedure showed correlation coefficients of 0.98 and 0.98, respectively.

Interference from various urinary metabolites was insignificant.

In a small-scale screening of elderly conducted at Penghu county in Taiwan (n=80), we were able to identify a group of twenty individuals having hyperhomocysteinemia (>15 μmole/L).

Three of them were found to be positive for XA as analyzed by the proposed method, which correlated excellently with the results of the activation coefficient method for RBC’s AST/B6 functional test.

These data confirm the usefulness of the proposed method for identifying urinary XA as an indicator of vitamin B6 deficiency-associated hyperhomocysteinemic condition.