Liangqin Xie,Zeyuan Deng,Jie Zhang,Huanhuan Dong,Wei Wang,Banghuai Xing,Xiaoru Liu
Flavonoids are well known for their extensive health benefits. However, few studies compared the differences between flavonoid O-glycoside and C-glycoside. In this work, flavonoid O-glycoside (isoquercitrin), C-glycoside (orientin), and their aglycones (quercetin and luteolin) were chosen to compare their differences on antioxidant activities and metabolism during in vitro digestion and in vivo. In vitro digestion, the initial antioxidant activity of the two aglycones was very high; however, they both decreased more sharply than their glycosides in the intestinal phase. The glycosidic bond of flavonoid O-glycoside was broken in the gastric and intestinal stage, while the C-glycoside remained unchanged. In vivo, flavonoid O-glycoside in plasma was more elevated than C-glycoside on the antioxidant activity; however, flavonoid C-glycoside in urine was higher than O-glycoside. These results indicate that differences of flavonoid glycosides and their aglycones on antioxidant activity are closely related to their structural characteristics and metabolism in different samples. Aglycones possessed higher activity but unstable structures. On the contrary, the sugar substituents reduced the activity of flavonoids while improving their stability and helping to maintain antioxidant activities after digestion. Especially the C-glycoside was more stable because the stability of the C–C bond is higher than that of the C–O bond, which contributes to the difference between flavonoid O-glycoside and C-glycoside on the absorption and metabolism in vivo. This study provided a new perspective for comparing flavonoid O-glycoside, flavonoid C-glycoside, and their aglycones on their structure–activity relationship and metabolism.Keywords:flavonoid;O-glycoside;C-glycoside;aglycones;in vitro digestion;antioxidant activity
The sodium–glucose co-transporter 2 (SGLT2) plays an important role in mediating glucose reabsorption within the renal filtrate and regulating blood glucose levels, which makes it a well-known target for diabetes mellitus. A number of SGLT2 inhibitors (SGLT2i) have been established as important antidiabetic drugs, and research on new SGLT2i with high affinity is ongoing. Herein, 101 compounds were screened from a compound library (approximately 16,000 compounds) using a virtual screening workflow that integrated various docking programs, pharmacophore modeling, and druggability filter. To verify the results of virtual screening, we established a HK-2 cell model with d-glucose derivative 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-d-glucose (2-NBDG) for measuring glucose uptake via SGLT2. 12 candidate compounds were selected and purchased for subsequent experimental validation. Among these, 3 non-glycoside compounds significantly inhibited the 2-NBDG uptake in a dose-dependent manner and their IC 50 values for SGLT2 were 71.43 μM, 72.66 μM, and 91.44 μM, respectively. Mechanism studies demonstrated that all 3 compounds significantly downregulated SGLT2 level and activated silent information regulator 1 (SIRT1) expression in high-glucose-induced cell injury models. These findings confirmed the ability of these compounds to bind to SGLT2 and also revealed their potential mechanisms in regulating oxidative stress and metabolism. Furthermore, molecular dynamics simulation indicated the high binding stability of SGLT2 and 3 compounds complexes during a 100-ns simulation period. In conclusion, our results identified 3 potential SGLT2i and preliminarily elucidated their mechanism of action, which lays the foundation for the development of novel and potent non-glycoside SGLT2i in future. Graphical
危险品化学品经营许可证（带存储）