Determination of 3-hydroxyanthranilic acid in the sweat of healthy older adults.

3-Hydroxyanthranillic acid (3HAA) is one of the key metabolites from the tryptophan (TRP) metabolism pathway and is associated with aging, age-associated diseases, and healthy lifespan extension. This study aims to detect 3HAA in the sweat of healthy older adults using simple, high-performance liquid chromatography (HPLC) method. Chromatographic separation using 20 mmol/L sodium acetate, 3 mmol/L zinc acetate, and 7% (v/v) acetonitrile as mobile phase is possible to simultaneous detect 3HAA, KYN, and TRP with UV and fluorescence detection, respectively, under 6 min. This method demonstrated excellent linearity with coefficient of determination (r(2)) greater than 0.998 for all analytes. The linear range were 0.05-6 µg/mL for TRP, 0.1-6 µg/mL for KYN and 0.2-6 µg/mL for 3HAA. Percentage recoveries from spiked in human sweat ranged from 90 ± 7-101 ± 3 for TRP, 86 ± 1-92 ± 3 for KYN, and 96 ± 1-103 ± 4 for 3HAA. The precision (%RSD) of repeatability and reproducibility is less than 3% and 6%, respectively. This method was used in a cross-sectional study with 81 participants aged 50-79 years, selected randomly from a local primary healthcare hospital's sampling frame. A detectable amount of 3HAA was observed in all sweat samples, marking the first report of 3HAA presence in human sweat. Additionally, the results revealed that the 3HAA sweat levels increased with age analyzed in three different age groups ranging from 50-59, 60-69, and 70-79. These findings enhance our understanding of sweat profiles and their correlation with aging, potentially further improving early diagnosis, disease monitoring, and development of customized treatment programs for older adults.