Effect of astilbin on experimental diabetic nephropathy in vivo and in vitro.

Astilbin, a flavonoid compound, was isolated from the rhizome of Smilax glabra Roxb. This study was conducted to investigate the efficacy of astilbin on experimental diabetic nephropathy (DN) in vivo and in vitro and its possible mechanisms. Astilbin was added in high glucose stimulated HK-2 cells, streptozotocin-induced experimental DN, randomized to receive intragastric ( I. G.) astilbin to observe its anti-renal lesion effect. Results showed that astilbin inhibited high glucose stimulated HK-2 cell production of transforming growth factor-beta1 (TGF-beta1) and connective tissue growth factor (CTGF) in vitro, especially CTGF; analogic results was also found in vivo. I. G. of astilbin 2.5 mg/kg or 5 mg/kg significantly ameliorated renal function, reduced kidney index, while it increased body weight and survival time in animals. In addition there was no significant difference in blood glucose level between the STZ-treated group and the astilbin groups. Furthermore, astilbin ameliorated the pathological progress of renal morphology. Astilbin can exert an early renal protective role to DN, inhibit production of TGF-beta1 and especially of CTGF. We suggest that astilbin inhibition of CTGF may be a potential target in DN therapy. This work provides the first evidence for astilbin as a new candidate of DN therapeutic medicine.