A capillary electrophoresis (CE) method was developed for the screening of 5′-methylthioadenosine nucleosidase (MTAN) inhibitors in traditional Chinese drugs and small molecular compounds. In this method, reaction occurred at the capillary inlet during a predetermined waiting period, followed by electrophoretic separation of the reaction substrates and products. Parameters affecting separation efficiency and enzyme activity were evaluated systematically. The optimized conditions were as follows: 30 mM phosphate (pH 3.0) running buffer, 25 kV applied voltage, 20 mM HEPES (pH 6.0) reaction buffer, and 4 min incubation time. Under the optimized conditions, the Michaelis–Menten constant ( K m ) of MTAN was 3.44 μM, which agreed with the documented data. The proposed method was successfully applied for MTAN inhibitor screening from 21 natural extracts and 8 small molecular compounds. The results demonstrated the practical applicability of the at-inlet reaction-based CE method in screening of MTAN inhibitors from natural products and small molecular compounds.
Depeng Li,Meihong Zhang,A.La Teng Zhu La,Zhengtian Lyu,Xin Li,Yuqing Feng,Dan Liu,Yuming Guo,Yongfei Hu
The development of hyperuricemia (HUA) and gout is associated with dysbiosis of the gut microbiota. Quercetin can reduce serum uric acid levels and thus alleviate HUA by modulating the gut microbiota. However, the detailed mechanisms involved in this process are not fully understood. Here, we showed that quercetin significantly reduced the serum uric acid level in a chicken HUA model by altering the chicken cecal microbiota structure and function and increasing the abundance of Lactobacillus aviarius . An L. aviarius strain, CML180, was isolated from the quercetin-treated chicken gut microbiota. Strain characterization indicated that quercetin promoted the growth of L. aviarius CML180 and increased its adhesion, hydrophobicity, and co-aggregation abilities. Gavage of live L. aviarius CML180 to a mouse model of HUA—established by adenosine and potassium oxonate—reduced the serum uric acid level and alleviated HUA. The ability of L. aviarius CML180 to decrease the level of uric acid was due to its degradation of purine nucleosides, which are the precursors for uric acid production. A nucleoside hydrolase gene, nhy69 , was identified from the genome of L. aviarius CML180, and the resulting protein, Nhy69, exhibited strong purine nucleoside-hydrolyzing activity at mesophilic temperature and neutral pH conditions. These findings provide mechanistic insights into the potential of quercetin to treat HUA or gout diseases via a specific gut microbe.
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