The kidney antifibrotic effects of 5,7,3′,4′,5′-pentamethoxyflavone from Bauhinia championii in streptozotocin-induced diabetic rats: in vivo and in vitro experiments

CONTEXT: The antidiabetic effects of flavonoids have been reported, but it is still unclear whether 5,7,3′,4′,5′-pentamethoxyflavone, isolated from Bauhinia championii Benth. (Fabaceae), also exhibits such properties. OBJECTIVE: To isolate 5,7,3′,4′,5′-pentamethoxyflavone from B. championii using high-speed countercurrent chromatography and examine its potential in treating diabetic nephropathy. MATERIALS AND METHODS: The phytochemical constituents from the stems of B. championii were separated and purified with high-speed countercurrent chromatography; 5,7,3′,4′,5′-pentamethoxyflavone (PMF) was identified by mass spectrum, (1)H-NMR, and (13)C-NMR. After exposing mesangial cells to 30 mM glucose and either 5 μM or 10 μM PMF for 6 h, the levels of fibronectin (FN) and p-Smad2/3 were analyzed using Western blotting. Male Sprague–Dawley rats were injected intraperitoneally with 55 mg/kg streptozotocin to induce diabetes and then were randomized into three groups (n = 10): vehicle administration, low-dose (5 mg/kg) PMF, and high-dose (25 mg/kg) PMF by intragastric gavage for 3 months. A healthy group was included as the control. RESULTS: Compared to the diabetic group, low-dose and high-dose PMF treatment decreased the phosphorylation of Smad2/3 by 0.54- and 0.52-fold, and the accumulation of FN decreased by 0.82- and 0.77-fold in vitro; the phosphorylation of Smad2/3 was decreased by 0.39- and 0.37-fold, and the accumulation of FN decreased by 0.47- and 0.40-fold in vivo, respectively. Furthermore, PMF alleviated the glomerular basement membrane thickness and foot process fusion. CONCLUSION: The findings suggest for the first time that PMF may be a promising treatment option for diabetic kidney fibrosis, which warrants additional clinical investigation.