Amelioration of diabetic nephropathy by dried Rehmanniae Radix (Di Huang) extract

The effects of dried Rehmanniae Radix (Di Huang) extract were investigated using a diabetic nephropathy model: rats given streptozotocin after nephrectomy. The results showed that this crude drug reduced the magnitudes of the increases in glucose, urea nitrogen, 5-hydroxymethylfurfural and thiobarbituric acid (TBA)-reactive substance levels, with the effects being most marked in the high blood glucose group. The renal histopathological lesions, which were conspicuous in rats not given dried Rehmanniae Radix extract, were ameliorated considerably in the high blood glucose group given this extract. It appears that dried Rehmanniae Radix extract may be useful as a therapeutic agent for inhibiting the progression of diabetic nephropathy. On the basis of these results, the possible mechanisms of action of this crude drug are discussed.