Protection of PC12 cells against superoxide-induced damage by isoflavonoids from Astragalus mongholicus.
OBJECTIVE
To further investigate the neuroprotective effects of five isoflavonoids from Astragalus mongholicus on xanthine (XA)/ xanthine oxidase (XO)-induced injury to PC12 cells.


METHODS
PC12 cells were damaged by XA/XO. The activities of antioxidant enzymes, MTT, LDH, and GSH assays were used to evaluate the protection of these five isoflavonoids. Contents of Bcl-2 family proteins were determined with flow cytometry.


RESULTS
Among the five isoflavonoids including formononetin, ononin, 9, 10-dimethoxypterocarpan-3-O-beta-D-glucoside, calycosin and calycosin-7-O-glucoside, calycosin and calycosin-7-O-glucoside were found to inhibit XA/ XO-induced injury to PC12 cells. Their EC50 values of formononetin and calycosin were 0.05 microg/mL. Moreover, treatment with these three isoflavonoids prevented a decrease in the activities of antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), while formononetin and calycosin could prevent a significant deletion of GSH. In addition, only calycosin and calycosin-7-O-glucoside were shown to inhibit XO activity in cell-free system, with an approximate IC50 value of 10 microg/mL and 50 microg/mL. Formononetin and calycosin had no significant influence on Bcl-2 or Bax protein contents.


CONCLUSIONS
Neuroprotection of formononetin, calycosin and calycosin-7-O-glucoside may be mediated by increasing endogenous antioxidants, rather by inhibiting XO activities or by scavenging free radicals.
Yu
De-Hong
DH
The State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100083, China.
Bao
Yong-Ming
YM
An
Li-Jia
LJ
Yang
Ming
M
D000818:Animals; D027883:Astragalus Plant / Q000737:chemistry*; D005960:Glucosides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D007529:Isoflavones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D016716:PC12 Cells; D020011:Protective Agents / Q000302:isolation & purification / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D013482:Superoxide Dismutase / Q000378:metabolism; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D005960:Glucosides; D007529:Isoflavones; D020011:Protective Agents; D019253:Proto-Oncogene Proteins c-bcl-2; C121707:7,3'-dihydroxy-4'-methoxyisoflavone; C007768:formononetin; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase; D005978:Glutathione