Reduction of urinary uric acid excretion in patients with proteinuria.

Serum uric acid (UA) concentration is positively associated with proteinuria. However, the relationship between proteinuria and urinary metabolites of purine metabolism remains unknown. This study developed a hydrophilic interaction chromatography (HILIC)-based HPLC method with ultraviolet detection (UV) to quantify creatinine (Cr), UA, xanthine, and hypoxanthine in human urine simultaneously. The urinary concentrations of UA and Cr obtained by our method are consistent with those measured by an autoanalyzer. The HPLC-HILIC-UV method was validated as selective and robust with simple sample preparation for measuring UA, xanthine, hypoxanthine and Cr, which is suitable for large clinical studies. The UA/Cr ratios in random urine samples were 5.5 times lower in proteinuria patients (0.077±0.008) than in healthy individuals (0.424±0.037). Moreover, the UA/hypoxanthine ratio in proteinuria patients was approximately 10 times lower than that in healthy individuals. Our findings revealed a reduced urinary UA excretion, which is one of the factors leading to increased serum UA in proteinuria patients.

Application of metabonomic strategy to discover an unreported active ingredient in LiuWeiDiHuang pills suppressing beta-glucuronidase.

Identification of the bioactive ingredient from traditional Chinese medicine (TCM) remains a challenging task by traditional approach that focuses on chemical isolation coupled with biological activity screening. Here, we present a metabonomics-based approach for bioactive ingredient discovery in LiuWeiDiHuang pills (LWPs). First, a non-targeted high-performance liquid chromatography ultraviolet (HPLC-UV) profiling of rat urine was used to discriminate urinary profiling intervened by LWPs. Orthogonal partial least-squares discriminant analysis (OPLS-DA) revealed that eight chromatographic peaks made a significant contribution to the classification of the LWPs group and the control group. Five of these chromatographic peaks were successfully isolated and identified as hippurate, genistein (GT), daidzein (DZ), and glucuronide conjugate of GT and that of DZ by mass spectroscopy (MS). Subsequently, we found that LWPs significantly decreased the activity of intestinal ß-glucuronidase by 18 % and exerted a dose-dependent inhibitory effect on rat liver lysosomal fraction, suggesting that LWPs were a ß-glucuronidase inhibitor. In the end, by inhibiting ß-glucuronidase-guided isolation, D-glucaro-1,4-lactone, a previously unreported ingredient of LWPs, was identified by MS, MS/MS, and nuclear magnetic resonance spectroscopy. Our findings indicated that metabonomics might increase research productivity toward the drug targets and/or bioactive compounds from TCM.