Screening and characterization of aldose reductase inhibitors from Traditional Chinese medicine based on ultrafiltration-liquid chromatography mass spectrometry and in silico molecular docking

Shenqi Jiangtang granule (SJG) is an ancient Chinese herbal formula used for treatment of Diabetes mellitus and its complications. To establish an integrated approach for discovery of effective Aldose reductase inhibitors (ARIs) from SJG. An integrated approach combining ultrafiltration-liquid chromatography-mass spectrometry (UF-LC-MS) with in silico molecular docking was established for development of ARIs. AR enzyme was separated from the rabbit's crystalline lens. The inhibitory activities of these compounds were detected by UV spectrophotometry with DL-glyceraldehyde as a substrate. Furthermore, molecular docking was used to understand the binding mechanism of these screened compounds interacting with AR. After optimization of AR reaction system and ultrafiltration incubation system, 17 active ingredients were screened from SJG by UF-LC-MS technique. Among these potential AR inhibitors, ginsenoside Rd exhibited the strongest activity with IC50 value of 45.77 μM. Three of them, calycosin, gomisin J and schisandrin A were demonstrated to be potential inhibitors for the first time, with IC50 at 447.34 μM, 181.73 μM, and 429.00 μM, respectively. Most of the active compounds exhibited competitive inhibition against AR. The docking scores of saponins were higher than that of lignans, which was consistent with the verification results. The results indicated that TCM formula with clinical efficacy was indeed hopeful source for screening active ingredients, and the combination of UF-LC-MS and in silico molecular docking was a universal and promising approach for development of effective enzyme inhibitors.