Abstract: Objective:To detect the repair effect of brain protein hydrolyzate (BPH) on the oxidative damage induced by H₂O₂ in the PC12 cells,and to optimize the prescription of BPH stomach floating tablets using the star design effect surface method. Methods: The PC12 cells in the logarithmic phase were divided into normal control group, model group (300 μmol·L^-1 H₂O₂),BPH group,artificial gastric juice-treated BPH (GBPH) group,artificial intestinal juice-treated BPH (IBPH) group,artificial gastric juice-treated BPH tablets (GBPH-T) group and artificial gastric juice-treated BPH floating tablets (GBPH-FT) group (The latter five groups were added with 20,40,60,80 and 100 mg·L^-1 BPH treated with different conditions);at the same time blank control group was set up. The PC12 cells in normal control group didn't receive any treatment,the blank control group was added with medium only,and the PC12 cells in model group were treated with H₂O₂ (300 μmol·L^-1) for 3 h.The cell viability was detected by MTT assay.Using Design-expert 8.0.6 Trial software,the dosages of HPMC-K4M,octadecanol and acrylic resin Ⅱ were used as the investigation factors,and the 8 h cumulative release in vitro was used as the evaluation index to optimize the prescription. Results: Compared with normal control group, the activity of PCl₂ cells in 60 mg·L^-1 BPH group was increased (P<0.05). Compared with model group,the vitalities of PC12 cells in BPH group,IBPH group,GBPH group and GBPH-FT group were increased significantly (P<0.05 or P<0.01). Compared with BPH group,the cell viability in IBPH group was decreased significantly (P<0.05),and there was no significant difference in GBPH group (P>0.05). Compared with GBPH-T group,the cell viability in GBPH-FT group was significantly increased (P<0.05).The optimal prescription was BPH 20 mg,lactose 10 mg,magnesium stearate 0.4 mg,microcrystalline cellulose 20 mg,HPMC-K4M 27 mg,octadecanol 63 mg,acrylic resinⅡ13 mg; all floating tablets drift in 5 s and sustained floating > 8 h;the difference of the measured value of 8 h cumulative release and the predicted value was not statistically significant(P>0.05). Conclusion: BPH has a significant repair effect on the H₂O₂-induced oxidative damage in the PC12 cells. Star design-effect surface method has good predictability and reproducibility;it is reasonable and feasible,and can be used to optimize the prescription of BPH stomach floating tablets.

Key words: star design, brain protein hydrolyzate, floating tablets, cell oxidative damage