In our previous study, we reported the renoprotective effect of
Hachimi-jio-gan, a Chinese traditional prescription consisting of eight medicinal plants, and also reported the effect of Corni Fructus (Cornus officinalis SIEB. et ZUCC.), a component of
Hachimi-jio-gan, on
diabetic nephropathy using diabetic rats. In this study, we investigated the effects of
morroniside isolated from Corni Fructus on renal damage in
streptozotocin-treated diabetic rats.
Oral administration of
morroniside at a dose of 20 or 100 mg/kg
body weight/d for 20 d to diabetic rats resulted in significant decreases in increasing serum
glucose and urinary
protein levels. Moreover, the decreased levels of
serum albumin and total
protein in diabetic rats were significantly increased by
morroniside administration at a dose of 100 mg/kg
body weight/d. In addition,
morroniside significantly reduced the elevated serum
urea nitrogen level and showed a tendency to reduce
creatinine clearance.
Morroniside also significantly reduced the enhanced levels of serum
glycosylated protein, and serum and renal
thiobarbituric acid-reactive substances.
Protein expressions related to the
advanced glycation endproduct (AGE) level and actions, oxidative stress such as
N(epsilon)-(carboxyethyl)lysine, as well as receptors for AGE and
heme oxygenase-1 were increased in diabetic rats, but the levels were also significantly decreased by the administration of
morroniside. This suggests that
morroniside exhibits protective effects against diabetic renal damage by inhibiting
hyperglycemia and oxidative stress. These results indicate that
morroniside is one component partly responsible for the protective effects of Corni Fructus and
Hachimi-jio-gan against diabetic renal damage.