Objective:To observe the effect of quercetin on free radical and nitric oxide (NO) and nitric oxide synthase (NOS) change after streptozotocin-induced diabetic in rats and analyze the protectiive mechanisms of quercetin on kindey in diabete rat. Method: The diabetic rats were induced by a single intraperitoneal injection of streptozotocin. The rats were randomly divided into three groups:normal group(A1

A2)

diabetic model group(B1

B2)

quercetin treatment group (C1

C2)

and each group was set into two groups (n=8). Respectively they were applied for the quercetin (50 mg·kg-1·d-1) lavage treatment for 6 weeks and 12 weeks and then killed for kidneys. The cell morphologic changes of renal tissue were observed by hematoxylin and eosin staining. The rats' renal hypertrophy index was calculated. Changes of the activity of superoxide dismutase (SOD) and NOS

the content of malondialdehyde(MDA)and NO in renal tissue were observed by means of spectro-photometry. Result: Quercetin treatment for 12 weeks could obviously reduce renal hypertrophy index (6.99±0.58)×10-3

(P<0.05).Quercetin treatment for 6 weeks and 12 weeks could obviously enhance SOD activities(165.31±14.89)

(148.33±13.22)U·mL-1

P<0.05)

reduce the MDA conten (17.89±2.88)

(19.46±3.02)μmol·L-1

(P<0.01)

the activities of NOS(15.13±2.89)

(17.65±2.46)ng·L-1

(P<0.01)and the contents of NO(0.42±0.12)

(1.41±0.48)μmol·L-1

(P<0.01)

and obviously improve the glomerular pathological changes. Conclusion: Quercetin can protect diabetic kidney of the rats with quercetin

which may be mediated by its anti-free radical and reducing the contents of NO and the activities of NOS.