ABSTRACT
Objective: To explore the protective effect of Polygonum minus ethanolic extract on cisplatin-induced neurotoxicity. Methods: In vitro test, total phenolic content assay and DPPH assay were performed to determine the antioxidant activity of Polygonum minus. For in vivo test, 30 male Sprague-Dawley rats were randomly divided into 5 groups: the control group, cisplatin 10 mg/kg, Polygonum minus 100 mg/kg, Polygonum minus 200 mg/kg and Polygonum minus 400 mg/kg. The control group and the cisplatin group were given distilled water whereas Polygonum minus groups received the respective dose of Polygonum minus extract orally for 14 d. On day 15, a single intraperitoneal administration of normal saline was given to the control group; while 10 mg/kg of cisplatin was given to the cisplatin group and Polygonum minus groups. Body weight, signs of illness, daily activity and mortality were observed at least once daily throughout the experimental period. On day 18, the anterior part of the brain was collected and processed for histological and ultrastructural analyses (right hemisphere). The remaining part (left hemisphere) of the brain was assayed to determine malondialdehyde and catalase levels for oxidative stress analyses. Results: Polygonum minus ethanolic extract possessed high phenolic content (977.6 mg GAE/g) and 95.9％ DPPH radical scavenging activities. No mortality was observed in all groups. Rats in the cisplatin group were weak and less active compared to Polygonum minus treated rats. In the cisplatin group, disorganised cellular layers of the cerebral cortex were observed whereas rats treated with low and mid doses of Polygonum minus extract had normal cerebral cortex as in the control group. Mild ultrastructural changes were observed in rats treated with low and mid doses of Polygonum minus extract. Meanwhile, low and mid doses of Polygonum minus extract significantly reduced malondialdehyde level whereas low and mid doses of Polygonum minus extracts groups significantly increased catalase activity compared to the cisplatin group. Conclusions: Polygonum minus ethanolic extract at 100 and 200 mg/kg attenuates cisplatin-induced oxidative stress in the cerebral cortex via its antioxidant activity.